IST-2003-507581 WINNER D2.5 v1.0 Duplex ... - Celtic-Plus

WINNER D2.5 v1.0AuthorsPartner Name Phone / Fax / e-mailSM Elena Costa Phone: + 49 89 636 44812Fax: + 49 89 636 45591e-mail: Elena.costa@siemens.comEAB Johan Nyström Phone: +46 8 757 05 86Fax: +46 8 5858 314 80e-mail: johan.nystrom@ericsson.comSM Sebastian Obermanns Phone: +49 2871 91 3842Fax: +49 2871 91 3387e-mail: sebastian.obermanns@siemens.comNOK Pauli Seppinen Phone: +358 50 4836701Fax: +358 7180 36213e-mail: pauli.seppinen@nokia.comUOULU Kari Hooli Phone: +358 8 553 2883Fax: +358 8 553 2845e-mail: kari.hooli@ee.oulu.fiSM David Thomas Phone: +44 1794 833431Fax: +44 1794 833589e-mail: david.thomas@roke.co.ukPage 5 (121)

WINNER D2.5 v1.07.3 Co-location of APs .....................................................................................................................1158. Conclusions .............................................................................................. 1168.1 Pros and cons of considered duplex arrangements ....................................................................1168.2 Duplex arrangements for the envisaged deployment scenarios ................................................1178.2.1 Short range cellular networks............................................................................................1178.2.2 Short range terminal to terminal........................................................................................1178.2.3 Wide area cellular networks ..............................................................................................1178.2.4 Access Point to Relay Station............................................................................................1188.3 Suggestion for the Way Forward ...............................................................................................118Page 10 (121)

WINNER D2.5 v1.0List of FiguresFigure 2-1: Basic duplex schemes; R=receive, T=transmit..........................................................................20Figure 2-2: Combination of duplex schemes ................................................................................................21Figure 2-3: TDD system ................................................................................................................................21Figure 2-4: Illustration of a potential interference situation between adjacent TDD carriers. ....................22Figure 2-5: FDD system overview ................................................................................................................23Figure 2-6: Hybrid TDD/FDD system ..........................................................................................................23Figure 2-7: Overview of FDD .......................................................................................................................25Figure 2-8: Overview of Half duplex FDD...................................................................................................25Figure 2-9: Overview of a half duplex FDD system with simple AP ..........................................................25Figure 2-10: Overview of TDD.....................................................................................................................26Figure 2-11: Overview of a DL oriented Hybrid TDD/FDD system from a spectrum perspective............26Figure 2-12: Overview of a DL oriented Hybrid system example from a device perspective ....................27Figure 2-13: Dual band TDD operation from the system point-of-view......................................................28Figure 2-14: Dual band TDD from the device perspective. .........................................................................28Figure 2-15: Band switching FDD Hybrid system .......................................................................................29Figure 3-1: Ad hoc commication...................................................................................................................33Figure 3-2: Schematic picture of a 2-hop network connection.....................................................................34Figure 3-3: Multi hop forwarding using scheme A.......................................................................................35Figure 3-4: Hops are divided by means of time division, Up- and downlinks by time division .................35Figure 3-5: Multi hop forwarding in scheme B ............................................................................................36Figure 3-6: Hops are divided by means of carrier separation and up- and downlinks by time division .....37Figure 3-7: Multi hop forwarding in scheme C ............................................................................................38Figure 3-8: Hops are divided by time division and up and down links by time and frequency division ....38Figure 3-9: Scheme D: Multi-hop forwarding ..............................................................................................39Figure 3-10: Hops are divided in time, up- and downlinks are divided by time and frequency division ...39Figure 3-11: Scheme E: Multi-hop forwarding.............................................................................................40Figure 3-12: Hops are divided in time and frequency, up- and downlinks are divided by time andfrequency division .................................................................................................................................41Figure 3-13: Scheme F: Multi-hop forwarding.............................................................................................42Figure 3-14: Scheme F: Hops are divided in time and frequency, up- and downlinks are divided by timeand frequency division...........................................................................................................................42Figure 3-15: Scheme G: Multi-hop forwarding ............................................................................................43Figure 3-16: Scheme G: Hops divided in time and transmission .................................................................43Figure 3-17: Scheme H: Multi hop forwarding.............................................................................................44Figure 3-18: Hops are divided by means of frequency and up- and downlinks are separated by frequencydivision...................................................................................................................................................44Figure 4-1: Duplex Filter at a Mobile Terminal Operating in Pure FDD ....................................................48Figure 4-2: UL UL and DL DL Interference Scenarios......................................................................49Figure 4-3: Near-Far Interference Problem...................................................................................................49Figure 4-4: UL DL Interference Scenario................................................................................................49Figure 4-5: DL UL Interference Scenario................................................................................................50Figure 4-6: Detail of a hexagonal cellular network with a N=7 clustering scheme.....................................53Figure 4-7: Issue of linear arrangement ........................................................................................................55Figure 4-8: Single-hop vs. multi-hop interference........................................................................................56Figure 4-9: Scheme A ACI scenarios............................................................................................................57Figure 4-10: Scheme B ACI scenarios..........................................................................................................58Figure 4-11: Scheme C: ACI scenarios.........................................................................................................59Figure 4-12: Scheme D: ACI scenarios.........................................................................................................60Figure 4-13: Scheme D: ACI scenarios.........................................................................................................60Figure 4-14: Scheme F ACI scenarios ..........................................................................................................61Figure 4-15: Scheme F with 2 relay stations.................................................................................................62Figure 4-16: Scheme G ACI scenarios..........................................................................................................63Figure 4-17: Scheme H ACI scenarios..........................................................................................................63Figure 4-18: Scheme H with 2 relay stations................................................................................................64Figure 4-19: Frequency Hopping ..................................................................................................................65Figure 4-20: Time Slot Hopping ...................................................................................................................66Figure 4-21: Cross and Auto Correlation Functions for a 64-Symbol Walsh Code ....................................66Figure 4-22: Cross and Auto Correlation Functions for (64,4,14) ZCZ Sequence Set................................67Figure 4-23: Centralised Resource Management..........................................................................................68Figure 4-24: Interference Avoidance Using Adaptive or Switched Beam Antennas ..................................68Page 11 (121)

WINNER D2.5 v1.0Figure 4-25: Simplified Scenario Used in TDD Interference Analysis........................................................71Figure 4-26: TDD Frame Structure for Simplified Scenario........................................................................71Figure 4-27: The Effect of Traffic Asymmetry on Crossed-Slot EbNo for Case B.....................................80Figure 4-28: Comparison Between Cases B and C of EbNo for Crossed Slots. Assumes Cell A Uses a 1:1DL:UL Ratio..........................................................................................................................................81Figure 4-29: Comparison Between Cases A, B and C of EbNo for Uplink Uncrossed Slots in Cell B.Assumes Cell A Uses 1:1 Downlink to Uplink Ratio...........................................................................81Figure 5-1: Possible block diagram of a transceiver operating in TDD.......................................................87Figure 5-2: Possible block diagram of a transceiver operating in FDD .......................................................88Figure 5-3. Possible block diagram of a transceiver operating in (T+F)DD................................................89Figure 5-4: Possible block diagram of a transceiver operating in CDD.......................................................90Figure 5-5: Dynamic range problem of the CCD .........................................................................................90Figure 5-6: MT used in DL oriented hybrid..................................................................................................91Figure 5-7: Example of operating in dual band TDD hybrid at two different bands...................................91Figure 5-8: TX Spectrum masks. For convenience, allowed ACPR is shown as pronounced....................95Figure 5-9: Adjacent-channel blockers and selectivity. RX filtering suppresses adjacent-channelinterference, but not inband-interference due to the TX ACPR of the blocker ...................................98Figure 6-1: Spectrum arrangement for coexisting pure and half duplex FDD...........................................104Figure 6-2: Spectrum arrangement for coexisting pure FDD and TDD.....................................................104Figure 6-3: Spectrum arrangement for coexisting pure FDD and downlink oriented hybrid concepts ....105Figure 6-4: Spectrum arrangements for coexisting FDD and dual band TDD ..........................................105Figure 6-5: Illustration on the guard band definition..................................................................................109Figure 6-6: Illustration on the definition of relaxed guard bands for MT..................................................111Figure 6-7: Guard band portion from total system bandwidth as function of total system bandwidth .....114Page 12 (121)

WINNER D2.5 v1.0List of TablesTable 2-1: Overview of duplex concepts ......................................................................................................23Table 4-1: Duplex Schemes Suffering Self Interference ..............................................................................48Table 4-2: Duplex and Forwarding Schemes s Suffering Self Interference.................................................52Table 4-3: CCI on RS/AP to MT radio links ................................................................................................54Table 4-4: CCI on relay links ........................................................................................................................55Table 4-5: Applicability of Duplex Schemes for Interference Scenarios.....................................................69Table 4-6: Summary of EbNo Equations for TDD Interference Scenarios..................................................79Table 5-1: Basic system parameters..............................................................................................................92Table 5-2: AP and MT TX ACPR requirements...........................................................................................94Table 5-3: Conversion of TX noise floors to spectrum mask far-limit requirements..................................94Table 5-4: AP and MT spectrum masks: dBc values, and how they were determined................................95Table 5-5: Maximum Rx blocking power: requirements and technical limits.............................................97Table 5-6: RX phase noise requirements due to blockers ............................................................................99Table 5-7: Collected PLL requirements ........................................................................................................99Table 5-8: Equivalent RF requirements for an FDD system ......................................................................100Table 6-1: Scenarios for coexistence of duplex concepts...........................................................................103Table 6-2: Interference types in the coexistence scenarios.........................................................................106Table 6-3: Transmission power, cable losses and antenna gains................................................................107Table 6-4: Example cases with physical separations, coupling losses, and multiple interference margins..............................................................................................................................................................107Table 6-5: Transmitter noise floor requirements for AP in interference examples ...................................108Table 6-6: Transmitter noise floor requirements for RS in interference examples....................................108Table 6-7: Transmitter noise floor requirements for MT in interference examples...................................108Table 6-8: Estimates for the guard bands based on transmitter noise floor requirements .........................109Table 6-9: Relaxed limits for coexistence interference ..............................................................................110Table 6-10: Estimates for the guard bands based on relaxed requirements ...............................................111Table 6-11: Guard band estimates for pure FDD / half duplex FDD coexistence.....................................111Table 6-12: Guard band estimates for half duplex FDD / pure TDD (and pure FDD / pure TDD)coexistence...........................................................................................................................................111Table 6-13: Guard band estimates for half duplex FDD / DL oriented hybrid (and pure FDD / DL orientedhybrid) coexistence..............................................................................................................................112Table 6-14: Guard band estimates for half duplex FDD / dual band TDD hybrid (and pure FDD / dualband TDD hybrid) coexistence............................................................................................................112Table 6-15: Guard band estimates for pure TDD / DL oriented hybrid coexistence.................................112Table 6-16: Guard band estimates for DL oriented hybrid / dual band TDD hybrid coexistence.............113Page 13 (121)

WINNER D2.5 v1.0GlossaryABBAnalog baseband filterACIAdjacent channel interferenceACPAdjacent channel powerACPR Adjacent channel power ratioACSAdjacent channel selectivityADC Analog-to-digital converterAGC Automatic gain controlANSI American National Standard InstituteAPAccess pointBAW Bulk Acoustic WaveBBBasebandBCABorrowed Channel AllocationBRAN Broadband Radio Access NetworkBSBase StationBWBandwidthC/ICarrier-to-interferenceCCDCharge-Coupled DeviceCCICo-Channel InterferenceCDD Code-division duplexingCDMA Code Division Multiple AccessCECCommission of the European CommunitiesCIRCarrier to Interference RatioCoordinated When two TDD cells use the same switching point(s)CPCyclic PrefixCSMA Carrier Sense Multiple AccessDAC Digital-to-analog converterdBdecibelDBdual bandDCDirect currentDCA Dynamic Channel AllocationDCFDistributed Control FunctionDiCo Direct conversionDLDownlinkETSI European Telecommunications Standards InstituteEVM Error vector magnitudeFCAFixed Channel AllocationFDDFrequency-division duplexingFDMA Frequency-division multiple accessFFTFast Fourier TransformationFNForwarding NodeFWA fixed wireless access (802.16)GBGuard BandGPGuard PeriodGPSGlobal Positioning SystemGSM Global System for Mobile CommunicationHAHyper AccessHCHigh CarrierHDR High Data RateIBSS Independent Basic Service SetICCInternational Conference on CommunicationsXI D Interference from the downlink of Cell XIEEE Institute of Electrical and Electronics EngineerIFIntermediate FrequencyIFDMA Interleaved Frequency Division Multiple AccessIFFTInverse Fast Fourier TransformIIPinput intercept pointsIIP2Second-order input intercept pointIIP3Third-order input intercept pointIMD2 Second-order intermodulation distortionIMD3 Third-order intermodulation distortionPage 14 (121)

WINNER D2.5 v1.0IPInternet ProtocolISTInformation Society TechnologiesXI U Interference from the uplink of Cell XLANLocal Area NetworkLCLow CarrierLNALow noise amplifierLOLocal oscillatorLOIIn-phase LO signalLOQQuadrature-phase LO signalLOSLine-Of-SightMAC Medium Access ControlMANET Mobile Ad hoc NetworkMCMulti-CarrierMCL Minimum coupling lossMCS Modulation and Coding StatesMIMO Multiple input, multiple outputMSMobile StationMTMobile Terminalm X Number of mobiles in Cell X allocated crossed slots (related to r X )M XTotal number of mobiles in Cell XNBNarrowbandN CNumber of crossed-slotsNFNoise figureNLOS Non Line of SightOFDM Orthogonal Frequency Division MultiplexingOFDMA Orthogonal Frequency Division Multiple AccessOHOverheadPAPower amplifierPAPR Peak-to-Average Power RatioPARPeak-to-average power ratioPHYPhysical layerPLPath LossPLLPhase-locked loopPLMN Public Land Mobile NetworkXP r Power received by the access point from a mobile station in Cell XXP t Power transmitted by a mobile distance r X from the centre of Cell XQAM Quadrature amplitude modulationQPSK Quadrature phase-shift keyingXQ r Wanted signal power received by a mobile station in Cell X.XQ t Power transmitted per user by the access point in Cell XRFRadio frequencyRFIC Radio Frequency Integrated CircuitRSRelay StationRSSI Received signal strength indicatorr XRadius within Cell X where mobiles are allocated to crossed-slotsRXReceiver, receptionDR X Downlink data rate per user in Cell XUR X Uplink data rate per user in Cell X.SAW Surface Acoustic WaveSCSingle CarrierSINR Signal-to-Interference-plus-Noise RatioSISO Single-input, single-outputSNRSignal-to-noise ratio(T+F)DD Time & Frequency Division DuplexTDDTime-division duplexingTDMA Time-division multiple accessTRTechnical ReportTRXTransceiverTSTechnical SpecificationTXTransmitter, transmissionULUplinkUMTS Universal Mobile Telecommunications SystemUTRA Universal Terrestrial Radio AccessPage 15 (121)

WINNER D2.5 v1.0UTRANWBWCDMAWINNERWLANWWRFZCZUniversal Terrestrial Radio Access NetworkWidebandWideband Code Division Multiple AccessWireless Initiative New RadioWireless Local Area NetworkWireless World Research ForumZero Correlation ZonePage 16 (121)

WINNER D2.5 v1.02. Basic description of duplex schemes2.1 IntroductionThe purpose of this chapter is to define the basic duplex schemes, as well as defining a commonterminology throughout the whole document. Originally, the term “duplex” relates to multiplexing oftransmission and reception and is thus device specific. Furthermore, it is often used to characterise awhole communication system implying that all devices use the same duplex scheme. However, this isonly a special case. In fact, different terminals in a system may employ different duplex schemes whichrequires a more detailed definition. A third meaning of ‘duplex’ is related to spectrum allocation issueslike the necessity of paired or unpaired bands, guard bands etc. In this document, these different viewswill all be treated.The chapter is organised as follows. In section 2.2, named Terminology, a brief definition of severalconcepts is given. Section 2.3 describes basic duplex schemes from a a device perspective. With a‘device’ we can mean an Access Points (AP), a Mobile Terminals (MT), or a Relay Stations (RS).InSection 2.4 the spectrum allocation perspective is considered. Finally, in Section 2.4, the two perspectivesare combined and six duplex concepts are identified. Fundamental similarities and differences are pointedout.2.2 Terminology2.2.1 Uplink (UL) and downlink (DL)The UL is defined as the set of resources used for communication from an MT to an AP, from an MT toan RS or from an RS to an AP, that is, in the general direction from the user towards the network.The DL is defined as the set of resources used for communication from an AP to an MT, from an RS to anMT or from an AP to an RS, that is, in the general direction from the network towards the user.When two MTs are communicating with each other, directly or via one or more RSs, this nomenclaturemight seem misleading (since no network is present) . This will be dealt with in section 3.3 that deals with‘ad hoc’ communication.2.2.2 Downstream/upstreamThis refers to the direction of traffic. Traffic transmitted on a downlink is transmitted downstream andtraffic transmitted on an uplink is transmitted upstream.2.2.3 Duplex schemeA duplex scheme is a common understanding between the devices how the total radio resources should bedivided into uplinks and downlinks.2.2.3.1 Frequency division duplex (FDD)In FDD, the up- and downlink transmissions take place in different spectrum bands, but may potentiallybe scheduled to occur simultaneously.2.2.3.2 Time division duplex (TDD)In TDD; the up- and downlink transmissions take place scheduled at different times, that is, nonsimultaneously,but in the same frequency band.2.2.3.3 Hybrid schemesVarious combinations of the TDD and FDD principles are possible as will be described later.2.2.4 Band switchingA device might employ band switching in order to exchange the roles of the UL s and DLs: the UL bandis used for DL transmission, and vice versa. This can be useful for a RS in certain scenarios (as will beshown in section 3.4).2.2.5 Paired and unpaired bandsFDD based duplex schemes requires a pair of frequency carriers for communication, one for the UL andone for the DL. The set of UL carriers and the set of DL carriers constitute the UL and DL bands or thepaired band. Note that neither the number of UL and DL carriers need to be the same, nor do the sizes ofPage 18 (121)

WINNER D2.5 v1.0UL and DL carriers need to be the same, and hence the sizes of the UL and DL bands need not be thesame.TDD does not need a pair of carriers and thus the TDD band can be considered unpaired.2.2.6 Duplex distance (fixed/variable)In FDD the duplex distance is defined as the frequency distance between the center of the UL carrier andthe center of the DL carrier.This distance could be fixed in a system, or it could be variable.2.2.7 Switching pointIn a TDD system, the transceiver switches between a transmitter mode of operation and a receiver modeof operation, or vice versa. Whenever this happens, we have a switching point. Often a basic time period(or frame period) is defined that determines the UL/DL configuration. The more switching points withinsuch a period, the more the UL and DL periods are ‘interspersed’.2.2.8 Activity Profile and Activity factorThe activity profile of a user in the DL defines the time periods where the DL is active. The DL activityfactor is the average time fraction the activity profile is set for DL transmission.The activity profile of a user in the UL defines the time periods where the UL is active. The UL activityfactor is the average time fraction the activity profile is set for UL transmission.If several activity profiles for a link have the same activity factor, the difference between them lies in thelocation of switching points.Example: in a TDD system with a frame structure given by 6 time slots the ‘UUUDDD’ pattern and the‘UDUDUD’ both have UL and DL activity factors 3/6 and 3/6, respectively, but the activity profiles aredifferent due to different switching point locations. The latter pattern enables faster feedback of e.g.control information, but includes several UL/DL switching points (switching times) reducing the spectralefficiency.2.2.9 Duplex asymmetryThe duplex asymmetry measures the basic amount of time-frequency resources in the DL in relation tothe UL. Of course, other characteristics like modulation/coding, interference characteristics, receiversensitivity, power constraints etc., will also impact the capacity of the DL and UL link, respectively, sothe duplex asymmetry as defined above is only partially valid as a measure for the DL/UL capacityrelation. It is however useful as a measure how the ‘natural resources’ time and frequency are expended.In a TDD system, the duplex asymmetry is defined as the ratio of the DL activity factor and the ULactivity factor.In a FDD system, the duplex asymmetry is defined as the ratio between the amount of DL bandwidth andthe amount of UL bandwidth.In a hybrid system using both frequency and time to separate users, the duplex asymmetry is defined asthe product between the FDD duplex asymmetry and the TDD duplex asymmetry as defined above.2.2.10 Guard period (GP)A guard period is an idle time period during which the transmitter and receiver is switched off between aDL transmission and a subsequent UL transmission, or vice versa. For an AP, it might also be the timebetween two subsequent transmission periods to one or more users, or between two subsequent receptionperiods from one or more users.This time is needed in time slot based systems for turning on and off the radio transmitter and receiverhardware and get in a stable mode of operation. Moreover, this time might also be needed for timealignment in larger cells.Page 19 (121)

WINNER D2.5 v1.02.2.11 Duplex filterWhen an access point or a terminal has to transmit and receive a signal at the same time, like in a FDDsystem, it is important to suppress the impact of the transmitted signal on the received signal. This isaccomplished by means of a duplex filter that adds to the cost and complexity of the equipment.2.2.12 Channel bandwidthThe channel bandwidths may be different for the UL and DL in general. Also, multiple bandwidths arepossible for UL as well as for DL.2.2.13 Guard band (GB)Guard band is defined as frequency separation between one carrier’s upper bandwidth limit and anothercarrier’s lower bandwidth limit.2.3 Duplex schemes from a device perspective2.3.1 Basic schemesAssuming time and frequency as available resources, the following duplex arrangements are evident:1. TDD – time division duplex:transmission and reception are performed at the same frequency but at different time intervals;2. FDD – frequency division duplex:transmission and reception are performed at the same time but at different frequency bands;3. (T+F)DD:transmission and reception are performed at different frequency bands and at different timeintervals;The three basic duplex schemes are depicted in Figure 2-1 below. The ‘T’ and ‘R’ stand for transmissionand reception, respectively. Note that the three time axes indicate that the three grey ‘boxes’ occursimultaneously in time.frequencyTDD FDD (T+F)DDT R TTRRtimeFigure 2-1: Basic duplex schemes; R=receive, T=transmit2.3.2 Combination of duplex schemesBesides the basic duplex schemes defined above, various combinations are conceivable. There arebasically four different combinations which are depicted in Figure 2-2:1. TDD + FDD2. TDD + (T+F)DD3. FDD + (T+F)DD4. TDD + FDD + (T+F)DD =: hybridExchanging T ↔ R yields the dual duplex schemes which are not explicitly depicted here.Page 20 (121)

WINNER D2.5 v1.0frequencyTDD+FDD TDD+(T+F)DD FDD+(T+F)DD hybridT R T R TTRRRRRRRtimeFigure 2-2: Combination of duplex schemesWhereas the variants 1 and 3 get by with a single transmit and receive RF path, the variants 2 and 4requires an additional transmit or receive path.The FDD+(T+F)DD variant can be considered in conjunction with FDD since it only reflects adecoupling of transmission and reception in time without any impact on hardware complexity and design.The TDD+(T+F)DD variant is basically a TDD like approach employing one or more additional channelsfor reception or transmissions.2.4 Duplex schemes from a spectrum allocation perspective2.4.1 Cellular systemsWithin a cellular system consisting of Access Points (AP) and mobile terminals (MTs) three differentduplex approaches are conceivable aiming either at reduced interference, enhanced flexibility or acombination of both.2.4.1.1 TDD – time division duplexIn a cellular TDD system, BS and MTs share the same frequency band as depicted in Figure 2-3. Such aTDD system requires TDD to be used in any terminal. One advantage is that only one carrier is neededfor both links, i.e. an unpaired band, which could facilitate the search of spectrum for a Winner airinterface.In Figure 2-3, a possible frame structure is depicted, where a DL and an UL block can bedistinguished.frequencySwitchingpointDLULtimeFigure 2-3: TDD systemIn Figure 2-3, a slot structure within the DL and UL phase has been suggested by the dotted lines, whichcan be used for e.g. for channel allocation in a TDMA (time division multiple access) fashion. Such a slotstructure is used in e.g. UTRA TDD, [3GPPWCDMA], but is not necessary in principle, slotting couldoccur also in the frequency domain. Note also that in the case of a slot structure, all DL slots or UL slotsdo not need to be located consecutively, but in principle could be interspersed in any way. Thus, moreswitching points would occur.Page 21 (121)

WINNER D2.5 v1.0One of the advantages for TDD is that, since the UL and DL share the same frequency resource,theoretically the UL and DL share the same radio propagation characteristics, so yielding channelreciprocity. This will be further discussed in Section 3.2.Due to the time division, there is a minimum delay involved in all feedback loops, e.g. power control, linkadaptation, channel measurements etc. Delay issues will be discussed in more detail in Section 3.2.Duplex asymmetry can in principle be changed often by changing the location of the switching points.Care must be taken so that neighboring (geographically or spectrum wise) cells or systems using differentasymmetries are not affected by too severe DL to UL and UL to DL interference occurring in the “crossedslots”, see Figure 2-4. This issue will be addressed in Section 5. If the systems are uncoordinated a largerguard band between carriers might be necessary.frequencyDLSwitchingpointULPotential need forguard bandDLULtimeCrossed slotsFigure 2-4: Illustration of a potential interference situation between adjacent TDD carriers.2.4.1.2 FDD – frequency division duplexIn an FDD system, the UL and DL are separated by means of different frequencies, Figure 2-5. If they areoperated at the same time this requires a duplex filter for further suppression of the cross-linkinterference. The cost and complexity issues will be studied in Section 6.An FDD system requires one UL band of spectrum, and separately one DL band of spectrum that may ormay not equal the size of the UL band.Since transmission and reception can occur simultaneously, feedback delays can often be smaller than forTDD. However, FDD based systems does not have the inherent possibility to utilise radio channelreciprocity in some situations.Page 22 (121)

WINNER D2.5 v1.0frequencyDLULDuplexdistancetimeFigure 2-5: FDD system overview2.4.1.3 Hybrid combinationsSpectrum allocation schemes are possible where system communication can take place using say a TDDpart of the spectrum together with an FDD part, or even only one extra link.One example is to combine one TDD carrier with an extra downlink band, as depicted in Figure 2-6.There will be many other possibilities as will be clear in later sections.frequencyDLDuplexdistanceULDLtimeFigure 2-6: Hybrid TDD/FDD system2.5 Duplex concepts: combining device and spectrum allocation views2.5.1 Overview of the duplex conceptsIn this section we consider various duplex concepts as a whole, both from device perspective and fromspectrum allocation perspective.In the below table, an overview of the duplex concepts are formulated.Table 2-1: Overview of duplex conceptsSpectrum allocation Device perspectiveperspective AP TerminalDuplexconceptPure FDD Paired UL & DL bands +guard band between bandsCommentsFDD FDD E.g. WCDMA FDD,Ref [3GPPWCDMA]Page 23 (121)

WINNER D2.5 v1.0HalfduplexFDDPaired UL & DL bands +guard band between bandsFDD(T+F)DD(= halfduplex)E.g. GSM, ref [GSM]No duplex filter in terminalsPure TDD Unpaired band (+possiblyguard bands between carriers)TDD TDD E.g. WCDMA TDDref [3GPPWCDMA]DLorientedHybridULorientedHybridDual bandTDDHybridUnpaired band + additional DLbandUnpaired band + additional ULbandUnpaired band (+ possibly GBbetween carriers)HybridHybridTDD(T+F)DDpossibleFDDOrTDDOr(T+F)DDpossibleFDDOrTDDOr(T+F)DDpossibleTDD(T+F)DDpossibleNo duplex filter in terminalsCareful interference analysisneededMore complex APCareful interference analysisneededMore complex APCareful interference analysisneededNo duplex filters in terminal.Careful interference analysisneededBandswitchedFDDHybridPaired UL & DL bands +guard band between bandsFDD+bandswitchedFDDFDD+bandswitchedFDDAlso relates to the RS operationin forwarding scheme E (ref.3.4.5)The combination of FDD andband switched FDD requires 2duplex-filters and a switchbetween them.2.5.2 Pure FDDAlso relates to the RS operationin forwarding scheme D (ref.3.4.4): The RS looks like an APfrom the MT point of view, andlike an MT from the AP pointof view.In the pure FDD case, simultaneous transmission takes place in the DL and UL. This makes it necessaryto have a duplex filter in the equipment, see Figure 2-7. This adds complexity and cost to especially theterminal as discussed in Section 6.One advantage is that the simultaneous transmission and reception facilitates fast feedback for e.g. powercontrol, link adaptation, channel and interference feedback etc.Page 24 (121)

WINNER D2.5 v1.0frequencyAPTMT1RRTtimeFigure 2-7: Overview of FDD2.5.3 Half duplex FDDIn the Half duplex FDD case, only the AP uses FDD. Each terminal employs (T+F)DD, see Figure 2-8:Overview of Half duplex FDD. This case can be viewed as a special case of the pure FDD case wherethere are restrictions on the scheduling of traffic so as to avoid simultaneous transmission and reception atthe MT.frequencyAP MT2 MT3TRRRTTtimeFigure 2-8: Overview of Half duplex FDDA very simple AP, for example for home use, can utilise (T+F)DD also from the AP perspective,eliminating the need for a duplex filter also in the AP, see Figure 2-9. This reduces the spectrumefficiency, but in some scenarios that might be acceptable.frequencyTAPRMT2RTtimeFigure 2-9: Overview of a half duplex FDD system with simple APHalf Duplex FDD may suffer a loss in bandwidth efficiency also in the case the number of active users istoo low. Indeed, due to the not overlapping in time of transmission and reception at one MT, if one or afew MTs, e.g., transmit only for a long period on the UL band, the DL band is not used during that time.Page 25 (121)

WINNER D2.5 v1.02.5.4 Pure TDDTDD based equipment does not need any duplex filters and users are separated in the time domain, seeFigure 2-10. Furthermore, from a link perspective, there is a possibility to change the allocation of ULand DL resources flexibly by changing the location of the switching point within the frame. However, asobserved with reference to Figure 2-4, this might cause severe AP-AP or MT-MT interference if theneighboring cells or TDD systems in adjacent carriers have a different UL/DL configuration (see Section5).frequencyAPTRMT2MT3R T R TtimeFigure 2-10: Overview of TDD2.5.5 DL and UL oriented HybridIn this case, the base station may be seen as operating in FDD but capable to transmit/receive in theuplink/downlink channel as well to cope with traffic asymmetries. Obviously, the use of an uplinkchannel for downlink transmission and vice versa leads to the same interference situations as in a TDDsystem, see Figure 2-11.frequencyDLDuplexdistanceULDLtimeFigure 2-11: Overview of a DL oriented Hybrid TDD/FDD system from a spectrum perspectiveWhereas the access points get more complex, the terminals need not be more complex than inconventional TDD or FDD systems. From the mobile terminal point of view, the following basicduplexing variants are applicable:a) Only (T+F)DDb) Only TDD + FDDc) Mixed (T+F)DD and TDD+FDD.Again Figure 2-12 shows a specific example for the mixed mode case. Here, MT1 communicates in FDDmode and MT3 in (T+F)DD mode. Since MT2 is only receiving data in this example, it could be either a(TDD+FDD) terminal or a (T+F)DD terminal.Page 26 (121)

RRWINNER D2.5 v1.0frequencyAP MT1 MT2 MT3TRRTTRTtimeFigure 2-12: Overview of a DL oriented Hybrid system example from a device perspectiveAn example of Hybrid FDD/TDD scheme is given as well by a TDD system with an additional uplinkbandwidth used e.g. for continuous transmission of signaling information from the MT, e.g. feedback onchannel estimation, in order to avoid the typical feedback delay implied by TDD (cf. Section 2.4.1.1).The DL oriented Hybrid could be suitable in a system where for example downloads of large files areanticipated. Cases where the MT should operate in full duplex FDD should be avoided due to theincreases complexity.2.5.6 Dual band TDD Hybrid:Another possibility is to allocate TDD carriers of different bandwidths, each of which operating accordingto the pure TDD case. A dual bandwidth approach, consisting of wideband channels (WB, ~100 MHz)and complementing “narrowband” channels (NB, ~10 MHz) would offer both complete coverage, widerange of data rates and efficient use of spectrum, yet without considerable additional demands forspectrum allocation [RIN-04].Achieving peak data rates of the order of 1 Gbps requires channel bandwidths of the order of 100 MHzeven with spectral efficiency 10 bps/Hz. However, there are several problems related to such widebandradio link. Firstly, wideband operation implies problems with area coverage, especially in uplink. This isbecause receivers collect noise over the whole channel bandwidth. Hence, as compared to lowerbandwidth systems, to achieve the same service quality either more power needs to be transmitted, orhigher coding needs to be resorted to. However, in terminals the available transmit power is limited, andeven in AP’s there are regulatory limits to the output power. On the other hand, higher coding lowers thespectral efficiency, since wide frequency band is used to transmit at low data rate. The dual concept offersa natural solution to the coverage problem: users located far from the AP can use the narrow-bandchannel, without need for complicated adaptation techniques.The wideband radio link also has difficulties to support low data-rate services, such as voice service orsmall IP acknowledgment messages. Narrow-band channel provides a convenient means for providingsuch services. Also radio access and other system information can be flexibly arranged with narrowchannels.An issue of utmost importance to wideband systems is power consumption in terminals. Conventionally,power consumption has been dominated by the power amplifier in the transmitter. For systems withbandwidth of the order of 100 MHz, also the power consumption in the receiver, especially in analog-todigitalconverters, and in digital processing become important, since sampling rate is proportional to thebandwidth. The issue is but pronounced by the introduction of MIMO, multiplying the number oftransmitters and receivers in the terminal. The dual band system is very attractive in the sense thatwideband channels are used only when necessary, and the remaining communication is done with lowersampling rate and essentially lower power consumption using the narrowband channels.Unlike with FDD or half-duplex FDD, in dual band TDD it is possible to operate adaptively in differentmodes, like ad-hoc, relay, and cellular mode. However, the potential interference problems are similar tothose of the TDD mode: synchronization is a necessity and coordination might be required. The schemecan also be configured to operate also in FDD and hybrid FDD/TDD mode by adapting the switchingpoints respectively.Page 27 (121)

WINNER D2.5 v1.0frequencySwitching pointDLULDuplexdistanceDLULtimeFigure 2-13: Dual band TDD operation from the system point-of-viewFigure 2-14: Dual band TDD from the device perspective.2.5.7 Band switching FDD Hybrid:This hybrid duplex approach has been recently proposed in [AA04]. Given paired spectrum blocks,instead of reserving a block for UL and the other for DL, their use is alternate periodically as shown inFigure 14.With this scheme, reciprocity can be achieved in each band, as in pure TDD case. However, if no propersynchronization is guaranteed in the switching between UL and DL in two adjacent bands or proper guardtime is introduced, this scheme may suffer the same interference issues as pure TDD. Moreover, as twopaired bands are used simultaneously for UL and DL, complex duplex filters may be required at both APsand MTs as in pure FDD.Page 28 (121)

WINNER D2.5 v1.0frequencySwitching pointULDLDLULDuplexdistancetimeFigure 2-15: Band switching FDD Hybrid systemPage 29 (121)

WINNER D2.5 v1.03. Relation between duplex schemes and future radio enablingtechnologies3.1 Discussion on the possibility of a flexible (configurable) air interfaceThe preferred solution would be to have one Winner duplex method that is used consistently in all typesof situations. However, in this section the possibility of having standard or even equipment that can beparameterised into two (or even more) duplex modes is investigated.One reason this could be interesting is that according to the Winner requirements [WIND71] the airinterface should cover a very wide range of scenarios from short range to wide area, including traditionalcellular applications, multihop (section 3.4), ad hoc (section 3.3) direct connections between terminalsand feeder scenarios.. Furthermore, various deployment issues can be relevant (see section 7). The issuesraised in these sections suggest that a single duplex mode may not be optimal in all scenarios, and that atwo mode solution should be considered.Another reason is that a wider range of spectrum allocations can be covered; both with respect to if pairedor unpaired bands are available, but also with respect to the interference situation to/from systems insurrounding these bands. For example, a neighbouring band might host a FDD system in whichintroduction of a TDD system might result in unwanted AP-AP or MT-MT interference.The purpose of this section is mainly to show the possibility, but since such flexibility will come with acost the trade off must be carefully weighted.There could be at least two ways for an air interface that can be parameterised into various duplexschemes.First, the possibility is to have a standard that is configurable (it does not necessarily imply configurableequipment) in order to be able to accommodate many various spectrum situations that might occur overthe years in various regions. This will ensure a long-lived basic standard even though the exact futurespectrum allocation is not decided at the completion of the standard itself. Individual products may ormay not support more than one mode; it is not necessarily a requirement.As an example, the WCDMA FDD and TDD modes [3GPPWCDMA] are examples of an existing twomode standard. However, the respective physical layer specifications are quite different. In a Winner twomodestandard the physical layer commonality should be made much larger than what is the case in[3GPPWCDMA].The next possibility is to also have equipment (APs and/or terminals) that can be dynamically configuredbetween various duplex modes in order to take advantage of specific properties of different duplexschemes or to avoid potential duplex related problems in some scenarios. Such advantages and problemsare addressed in the following Chapter 3 sections and in Chapters 5 and 6.As an example of this, the WCDMA FDD and TDD modes are designed to make multi mode terminalsfeasible and to perform hand over between the modes.In order to emphasise some commonalities between the duplex schemes some characteristics are partiallyrecalled from Chapter 2.The basic set of parameters that is different between the duplex schemes is the DL carrier frequency, theDL activity profile, the UL carrier frequency and the UL activity profile. Furthermore, the DL and ULbandwidths are crucial in defining duplex and spectrum properties. These six parameters together definethe duplex setting.For FDD, the UL and DL carrier frequencies are different, the UL and DL activity profiles are potentiallyoverlapping (thus requiring a duplex filter) and the UL and DL bandwidths may or may not be equal.For TDD, the UL and DL carrier frequencies are equal, the UL and DL bandwidths are equal (althoughthere might be a choice between several bandwidths, once the choice is made the UL and DL bandwidthsare equal) and the activity profiles are defined to be non-overlapping.Page 30 (121)

WINNER D2.5 v1.0For a Half Duplex FDD scheme ((T+F)DD seen from a terminal perspective), the UL and DL carriers aredifferent, the bandwidth may or may not be equal and the activity profiles must be non-overlapping (asfor TDD). From the AP perspective, the Half duplex FDD scheme looks like a pure FDD scheme.For the subsequent discussion in this section, a standard based on TDD and Half Duplex FDD isconsidered henceforth.The TDD and Half Duplex FDD schemes look very similar, if we look at the DLs and ULs separately.There is no reason why the definitions of the TDD DL and the Half Duple FDD DL must look muchdifferent from a standard perspective, except that some protocols need to be different in order to takeadvantage of certain duplex related properties (e.g. a Half Duplex FDD requires more signaling ofchannel parameters than a TDD system since in the latter case sometimes reciprocity can be exploited) ,or that TDD might require synchronization and coordination between APs. The same argumentation goesfor the UL.Furthermore, basic control channels need to have a common format for the modes. This includes for theDL possible control information for time and frequency synchronization, cell search and basic broadcastinformation. The UL includes Random Access channels. From a standards perspective, it should bepossible to parameterise some key parameters like those mentioned above, to get the various duplexschemes, but from a device complexity perspective, the different configurations will have implications.There are potential drawbacks with having configurable equipment, or multiple modes of the Winnerstandard running in the same geographical area. They include device complexity issues, the need forspectrum availability , and coexistence issues between the modes. The coexistence issues are addressed inChapter 6Having a configurable standard might help the Winner air interface to live for a long time since forvirtually any piece of spectrum, a suitable duplex concept can be used.Whether or not this should be adopted for the Winner air interface must be weighted with thedisadvantages of a more complex standard and testing, spectrum availability and equipment complexity.3.2 Link adaptation3.2.1 Channel reciprocityIn TDD there is the advantage over FDD and Half Duplex FDD solutions that a measurement of the ULpropagation channel gives an estimation of the propagation channel for the DL, or vice versa, since ULand DL transmission take place on the same band. This can be exploited by carrying out channelestimation at a BS on the basis of the received UL signal and use this estimate in DL, e.g. for channelallocation purposes or pre-equalisation approaches. The knowledge of such channel information at thetransmitter requires explicit feedback from the receiver in FDD and Half Duplex FDD based solutions,which requires signalling overhead.In TDD based multiple antenna system, like e.g. MIMO systems, the lack of need to feedback thechannel matrix is an advantage. However, this requires that the terminal transmits pilots on all its’antennas or in all beams (that will be used for DL link adaptation later) so that all relevant MIMOchannels are probed.The bandwidth, if only a few sub carriers are used in the UL, and the multiple access method might varybetween the UL and the DL, which complicates the exploitation of channel reciprocity. A solution to thismight include occasional transmissions of full-bandwidth pilots in the UL.One important thing to note for TDD is that any air interface or protocol delay between measurementsand usage will deteriorate the reciprocity. (Also in FDD delays are important when explicit signalling isneeded for the channel state information).Also, return channel measurements might not be available when required for non-scheduled users orduring times without UL activity unless some return control channel is permanently active.Also, interference in UL and DL will be different in any case and require feedback for accurateestimation. Knowledge about the propagation channel is often beneficial, but what is also important forlink adaptation of e.g. modulation and coding scheme and optimum MIMO processing is the experiencedPage 31 (121)

WINNER D2.5 v1.0interference and for best performance feedback also of the interference is important. The interferencelevels and characteristics is not reciprocal between the UL and DL in general and this potentially limitsthe benefits of channel reciprocity. This problem is addressed [TöCo04] where also a solution based onfeedback is proposed.Furthermore, receiver and transmitter filters, antenna configurations, and other parts of the Tx/Rx chainsare part of the perceived propagation channel and generally this will affect the reciprocity of the channel.Periodical calibration signals and measurements might be needed in order to maintain phase consistency.Further studies are needed in order to quantify such effects that may possibly affect standardsspecifications so that overall reciprocity is preserved. There might be a need for calibration of the chainsin order to have this under controlFor FDD, band-switching techniques might be employed to get the possibility to make use of channelreciprocity. However, more studies would be needed to investigate the performance/cost/complexity tradeoff.Thus, TDD offers the possibility of channel reciprocity, but several potentially limiting factors exist. Inorder to compensate for or control these factors, most likely feedback will be needed, and this limits theoriginal promise of reciprocity (the non-necessity of feedback). Hence, more studies are needed.3.2.2 Delay issuesIn general all feedback loops in a communication system, e.g. power control, adaptive coding andmodulation, adaptive resource allocation, interference measurement feedback, to mention a few, greatlybenefit from low air interface delays. Other sources for delay include propagation delays, switching timesbetween transmission and reception.In the pure TDD based or Half Duplex FDD based systems there are inherent delays between the UL andDL due to the time division structure. In the Hybrid solutions DL oriented Hybrid (or UL orientedHybrid), where TDD band is complemented with an extra UL (or DL) band with continuous transmissionthe inherent delays can be made smaller, see Figure 2-11.Common to all duplex schemes are processing delays, delays due to interleaving and coding, etc. Aproperly designed TDD or Half Duplex FDD system where the location of switching points are properlychosen will minimise such inherent delays, e.g. in a highly time varying channel, the alternating UL andDL blocks should be “interspersed”. The trade off between induced latency and the spectral efficiencyloss due to the guard interval required at each switching point should be properly evaluated.Thus, there seems to be a small fundamental advantage of FDD with respect to delays, although with acareful TDD or Half Duplex FDD activity profile design it might be possible to satisfy all delayconstraints.There are alternatives based on hybrid approaches where delays can be made smaller. In Chapter 2, theUL and DL oriented Hybrid TDD solutions consist of e TDD carrier supported by an extra UL (or DL)band that can be used for quick feedback signalling.3.3 Ad hocAn “Ad-hoc network” is a collection of wireless mobile nodes that self-configure to form a networkwithout the aid of any established infrastructure. The main discriminator for ad hoc networks that setthem apart from traditional wireless network classes is the need for the relay (and, hence route) ofmessages. The relay nodes (either all nodes or a sub-set) use a “decode and forward” scheme but not justan amplification of the RF signal. Mobile nodes handle the necessary control and networking tasks bythemselves, generally through a distributed control algorithm. “Ad-hoc networks” are “Multi-hopnetworks. (As defined in the WLAN standard [IEEE802.11], the independent basic service set (IBSS) isalso referred to as a simple case of an “ad-hoc network” although here all nodes are in each othertransmission range and there is no relaying.)Since there is no proper ‘uplink’ or ‘downlink’, the terms L1 and L2 (as for Link) are used here todescribe the link that terminal 1 and 2 use for transmission, respectively, see Figure 16. Only the two-hopsituation is shown, the three (or more)-hop situation is extended in an obvious manner.Page 32 (121)

WINNER D2.5 v1.0Terminal 1L1Terminal 2L2Figure 3-1: Ad hoc commicationIn order to set up a communication, the terminals must decide on resources for L1 and L2. If, say,terminal 1 announces its presence using a certain carrier frequency, terminal 2 must most likely scanseveral carriers in order to detect it. This must be done regardless of duplex scheme. Alternatives to suchan approach include explicit manual configurations and explicit signaling of the used carrier on apredefined common radio channel.If a FDD or Half Duplex FDD scheme is used, L1 could be chosen to reside in the ‘DL’ portion of thespectrum and L2 could be determined by reading information on L1 which resources L2 should use, or beimplicitly determined by a fixed duplex distance. However, it should be noted that if every terminalshould be capable to talk to every other terminal, the terminal must have band-switching capabilitieswhere the role of ‘DL’ and ‘UL’ changes, which have interference and hardware complexityconsequences. Furthermore, the interference to/from other MTs/APs operating in traditional fashion in thesame band can be substantial.If a TDD scheme is used, L2 clearly uses the same spectral resources as L1 but using another activityprofile. Hence, the direct connection MT-MT communication mode does not significantly differ from AP-MT communication mode and has no additional hardware drawbacks. The ad hoc network must havesome synchronization and coordination mechanism that preferably works also when there is no traditionalnetwork AP within range that otherwise could facilitate synchronization.Regardless of the chosen duplex scheme, care must be taken in order to avoid harmful interference sincethere is no clear role of what is UL or DL, and interference to/from other equipment can occur. Mostlikely some power/range restrictions must apply. The 802.11 standard [IEEE802.11] is an example of aTDD based WLAN standard with protocols to handle such interference scenarios.Thus, in such ad hoc direct connection scenarios, there seem to be an advantage for TDD regardinghardware complexity. Since the communication take place in one rather than two carriers that are used inmixed roles of ‘UL’ and ‘DL’ carriers in FDD or Half duplex FDD or Hybrid solutions, it seems thatTDD might lead to simpler interference handling.3.4 Multihop communicationBeside “ad-hoc networks” infrastructure based networks, can also be classified as “Multi-hop networks”at which there are either fixed or mobile relay nodes that forward messages/traffic between networkelements on the same air interface. Main traffic directions are up- and downstream from the MTs to theAPs and vice versa, although it is not excluded that there might be local traffic with endpoints within themulti-hop network without getting relayed by the AP.In the following we have not assumed a particular physical or directional separation of the relay stationstransmitter and receiver antenna. Hence, separation of transmitted and received signal must be made inthe time and/or frequency domain.The terms UL and DL are used in the multi-hop to describe if the traffic is directed to or from the AP,respectively. Thus, in Figure 3-2 there are two DLs, L1 from the AP to RS, and L2 from the RS to theterminal. Similarly there are two ULs, L3 from the terminal to the RS, and L4 from the RS to the AP.We consider mostly 2 hops in the examples in this document; the terminology can be extended to morehops in an obvious and straightforward way.Page 33 (121)

WINNER D2.5 v1.0APL1RSHop 2RANHop 1L4L2L3TerminalFigure 3-2: Schematic picture of a 2-hop network connectionIn the sequel, there is a need to describe when a device (say an AP) is receiving and transmitting on acertain link. This will be noted by Ri and Ti, respectively, where i is the number of the link. Thus, lookingat Figure 3-2, the names T1 and R4 denote the communication from/to the AP, and T2, T4, R1, R3 denotethe actions of the RS, and so on.In the following sections we investigate several alternatives for the duplex schemes in the two hops. TheTDD based schemes have advantages and are most often considered for multi-hop scenarios in theliterature, but in the following also other possibilities based on FDD are included.3.4.1 Scheme AIn scheme A, all links use the same carrier frequency, and the 4 links are separated by means of timedivision, that is both hops make use of pure TDD. This is depicted in Figure 3-3 and Figure 3-4whereessentially the same information is displayed but where different aspects of the forwarding process arehigh lighted. Since similar pictures are given for all duplex possibilities short descriptions how tounderstand the pictures are given in this section.The numerical figure 1,2,3 or 4 on the arrows symbolises the links L1, L2, L3, or L4, respectively. Theline marked ‘carrier’ on which an arrow points or from which it originates depicts which carrier is usedfor which of the four links (for scheme A only one carrier/line is used).In the left part of Figure 3-3, the use of the carrier is highlighted, while the right part focuses on thetemporal usage, that is, when the links are activated in relation to each other. Note that we have 4 (notnecessarily equal sized) distinct slots in this scheme. The Figure 3-4 combines the spectral and temporalviews so as to give a simple overview of the scheme.This only requires the allocation of one carrier, but on the other hand the available nominal bandwidth isreduced since the single carrier has to be split into four mutually exclusive parts. In a well-designedsystem, such a reduction is more than offset by the increased capacity due to the hopping.Page 34 (121)

WINNER D2.5 v1.0Slot1 2 3 4APMTAPT1R4R2T314carrier^RSR1 T4T2R323RSMTFigure 3-3: Multi hop forwarding using scheme AIf more than 2 hops are used, time slots might be reused along the chain of hops to gain capacity.Hop 1 Hop 2frequencyT1APR4frequencyR1RST4 T2 R3timetimefrequencyMTR2T3timeFigure 3-4: Hops are divided by means of time division, Up- and downlinks by time divisionNote that the above is only the most basic scheduling of links. With more switching point cleverlylocated, the T1 and T2 (and T3, T4) phases could be interlaced in time. That is, the hops would still bedivided by means of time division albeit interlaced, but the delay between the first time the RS receivesthe data, and the first time the MT receives that data would be smaller. The more switching points, thesmaller delay, although the overall time for receiving all data would remain the same.Page 35 (121)

WINNER D2.5 v1.0The scenario above is characterised by the following:1) Hop 1 and 2 traffic is assigned in TDD fashion on the same carrier2) The RS operates in TDD fashion3) If an MT acts as an RS it does not need any other capabilities than in ‘pure RS’ operation or in ‘pureMT’ operation.4) The setup can be seen as two time-multiplexed TDD connections wherea) The AP uses TDDb) The RS uses TDD in hop 1 and 2c) The MT uses TDD3.4.2 Scheme BIn scheme B, the two hops use two different carriers, but on each hop pure TDD is used. If the RS has aduplex filter, simultaneous transmission and reception is possible in the RS and bit rates can be increasedcompared to case A (assuming all carriers have the same bandwidth as in case A). Also, thecommunication in hops 1 and 2 are more independent. In Figure 3-5(left & right) and Figure 3-6 there arenow two carriers one ‘high carrier’ (HC) and one ‘low carrier’ (LC)Slot 1 Slot 2APMTAPT1R4R2 T3HC14HChigh carrier (HC)low carrier(LC)RSR1 T4T2R3LC23LCRSMTFigure 3-5: Multi hop forwarding in scheme BPage 36 (121)

WINNER D2.5 v1.0Hop 1HCfrequencyT1APR4frequencyR1RST4frequencyMTHop 2LCT2R3R2T3timetimetimeFigure 3-6: Hops are divided by means of carrier separation and up- and downlinks by timedivisionIn the situation depicted in Figure 3-6 the RS needs band switching, but if the scheduling is such that theT1,T2,T3 and T4 transmission never overlap in time, the RS does not need band switching.The scenario above is characterised by the following:1) Hop 1 traffic is assigned to the HC in TDD fashion and Hop 2 traffic to the LC in TDD fashion2) The RS transmits and receives simultaneously at both the HC and LC3) The RS potentially needs band switching capabilities4) If an MT acts as an RS it may also needs band-switching capabilities, otherwise it receives on HCand transmits on LC as in traditional scenarios.5) The setup can be seen as time multiplexed (T+F)DD connections wherea) The AP uses TDDb) The RS uses TDD on HC in hop 1 and TDD on LC in hop 2c) The MT uses TDDIf the hop 1 carrier and the hop 2 carrier are located in adjacent channels or at least very close, theremight be a problem separating the L1 reception from the L2 transmission in the RS. In Figure 3-6it isassumed that a sufficient distance separates the carriers.If more than 2 hops are used, the carriers can be reused along the chain of hops.Above, in the figure, there is no delay between the start of R1 and T2, that is, between the hop 1 and hop2. Depending on the relaying concept, the delay could be substantial if for example decoding/re-encodingis employed in the RS, but if only amplification is used in the RS like in a repeater, the delay can benegligible.From Figure 3-6 it is clear that the RS needs to be transmitting and receiving on both the HC and LC atthe same time. Hence, it needs duplex filters and band switching capabilities. Especially if the RSfunctionality is also part of a user terminal this adds to complexity and cost, and complicates theinterference situation.3.4.3 Scheme CIn scheme C, (Figure 3-7 and Figure 3-8) hops are separated in time (like in scheme A) but the UL 1 and2 are separated from DL 1 and 2 also in the frequency domain. In this scheme the RS does not a needduplex filter.Page 37 (121)

WINNER D2.5 v1.0Slot1 2 3 4APMTAPT1R4R2 T3HC14LChigh carrier (HC)low carrier(LC)RSR1 T4T2R3HC23LCRSMTFigure 3-7: Multi hop forwarding in scheme CHop 1 Hop 2frequencyT1APR4timefrequencyR1RST2T4R3timefrequencyMTR2T3Figure 3-8: Hops are divided by time division and up and down links by time and frequencydivisiontimePage 38 (121)

WINNER D2.5 v1.0The scenario above is characterised by the following:1) Downstream traffic is assigned to the HC and upstream traffic to the LC.2) The RS transmits and receives at both the HC and LC, although not simultaneously.3) The RS needs band switching capabilities.4) If an MT acts as an RS it needs band switching capabilities, otherwise it receives on HC andtransmits on LC as in traditional scenarios.5) The setup can be seen as time multiplexed (T+F)DD connections wherea) The AP uses Half Duplex FDD or (T+F)DDb) The RS uses (T+F)DD in hop 1 and band-switched (T+F)DD in hop 2c) The MT uses (T+F)DD3.4.4 Scheme DIn this scheme the AP and MT operate in FDD mode while the RS operate in band switched FDD mode,see Figure 3-9 and Figure 3-10. Of course, if an MT should also serve as a RS, also the MT must be ableto operate in band-switched FDD mode.Slot 1 Slot 2APMTAPT1R4R2T3HC14LChigh carrier (HC)low carrier(LC)^RSR1 T4 R3T2HC23LCForwarding RS UE/BSMTFigure 3-9: Scheme D: Multi-hop forwardingHCfrequencyT1AP RS MTR1 T2R2Hop 1 Hop 2LCR4T4R3T3timetimetimeFigure 3-10: Hops are divided in time, up- and downlinks are divided by time and frequencydivisionThe scenario depicted within the 2 figures above is characterised as follows:Page 39 (121)

WINNER D2.5 v1.01) Upstream traffic is assigned to the high carrier (LC) and downstream traffic is assigned to the highcarrier (HC) as legacy FDD networks.2) The RS both receives and transmits on LC and HC carriers.3) The AP and the RS transmit time multiplexed on the same HC carrier. This is in analogy to a cellularnetwork at which BSes share the same carriers in a TDMA fashion.4) The MT and the RS transmit time multiplexed on the same LC carrier.5) The MT (as any) receives on HC and transmits only on LC carriers (as in a traditional FDD system).6) It can be interpreted as a FDD cellular network where APs or RSs represent the base stations andwith time division between adjacent cells on selected carriers.7) The following duplex scheme combinations are used. It can be seen as a FDD network with TDMAbetween adjacent cells on selected carriers.a) AP: FDDb) RS: FDD + band switched FDD Hybridc) MT: FDD3.4.5 Scheme EIn scheme E, see Figure 3-11 and Figure 3-12, the hops are divided both in time and frequency, as well asthe up- and downlink divisions. The RS must be able to transmit and receive in both the HC and the LCwhile the AP and MT operate in a (T+F)DD fashion.Slot 1 Slot 2APMTAPT1R4R2T3high carrier (HC)HC14LClow carrier (LC)RSR1 T4 R3T2RSLC32HCMTFigure 3-11: Scheme E: Multi-hop forwardingPage 40 (121)

WINNER D2.5 v1.0freAP RS Term. MTquencyT1 R1 T2R2Hop 1 Hop 2R4R3T4T3timetimetimeFigure 3-12: Hops are divided in time and frequency, up- and downlinks are divided by time andfrequency divisionThe scenario depicted above is characterised as follows:1) Upstream traffic is mapped to low and downstream traffic to the high carriers.2) The RS both receives and transmits on low and high carriers. Here it does not receive and transmit atthe same time (dual band TDD). It requires 2 separate receiver and 2 separate transmitter chains. Ifthe switching points at the low and high carriers are identical as depicted in the above figure, it doesnot require duplex filters.3) The AP and the RS transmit time multiplexed on the same high carrier. This is in analogy to acellular network at which BSes share the same carriers in a TDMA fashion.4) The MT and the RS transmit time multiplexed on the same low carrier.5) The MT (as any) receives on HC and transmits only on LC carriers (as in a traditional FDD system).6) It can be interpreted as a FDD cellular network where APs or RSs represent the base stations andwith time division between adjacent cells on selected carriers.7) The following combination of duplex schemes are used.a) AP: Half duplex FDDb) RS: Dual band TDD Hybridc) MT: half-duplex FDD3.4.6 Scheme FThis scheme uses an unequal mapping of transmit and receive FDD scheme at terminals and there mightbe potential interference problems with other terminals, see section 4.2.2.3.Page 41 (121)

WINNER D2.5 v1.0Slot 1 Slot 2APMTT1R4R2T3APhigh carrier (HC)HC14LClow carrier (LC)RSR1 T4 R3T2RSLC2 3HCMTFigure 3-13: Scheme F: Multi-hop forwardingfreAP RS MTquencyT1 R1 R3T3Hop 1 Hop 2R4 T2 T4R2time time timeFigure 3-14: Scheme F: Hops are divided in time and frequency, up- and downlinks are divided bytime and frequency divisionThe scenario depicted in Figure 3-14 above is characterised as follows:1) Every RS switches up- and downstream traffic from low to high carriers and vice versa (R1->T2 orR3->T4).2) Every device has a (semi-)fixed mapping of Rx/Tx to low and high carriers as depicted above.3) MTs with odd number of hops to the AP transmit on low and receive on high carriers. Those witheven number of hops do the opposite. According to the Tx/Rx mapping to low and high carriers alldevices can be categorised into AP-type and MT-type device. The RS, for example is a MT-typedevice and the first MT is an AP-type device.4) The MT’s complexity in full-duplex pure FDD is increased when it is able to switch their mapping ofTx/Rx to low and high carriers, because this requires 2 duplex filters and a switch to select betweenthem. These are not needed when operating in half-duplex FDD.5) The following duplex scheme combinations are used.a) AP: Half duplex FDDb) RS: FDD (or 2* Half duplex FDD)c) MT: Half-duplex (but with inversed mapping to low and high carriers)Page 42 (121)

WINNER D2.5 v1.03.4.7 Scheme GThis scheme is characterised by using both FDD and TDD terminals. The RS translates between FDD andTDD mode. This means that MTs that are directly connected to an AP may use for example pure or Halfduplex FDD and terminals that get relayed use TDD.Slot 1 Slot 2APMTT1R4R2T3high carrier(HC)HC1AP4 LClow carrier (LC)RSR1 T4 R3T2RSHC23LCMTFigure 3-15: Scheme G: Multi-hop forwardingfrequencyT1AP RS MTR1Hop 1 Hop 2R4 T2/4 R3R2T3time time timeFigure 3-16: Scheme G: Hops divided in time and transmissionThe scheme G depicted in Figure 3-16 is characterised as follows:1) The RS maps downstream traffic from a high carrier to a low carrier and upstream traffic is alwaysmapped to a low carrier.2) A MT that gets relayed uses a TDD duplex scheme3) The transmissions T2, T3, T4 can be assumed to be scheduled by the RS. That means the RS “owns”this low carrier (or at least the depicted time slots).4) The single block with two transmissions T2/T4 requires another multiplexing scheme between T2and T4. The detailed scheme (e.g. CDMA or FDMA) is not detailed here.5) The following duplex scheme combinations are used:a) AP: pure FDDb) RS: pure FDD and TDDc) Relayed MTs: TDDPage 43 (121)

WINNER D2.5 v1.03.4.8 Scheme HThis section discusses the case where a FDMA technique is utilised to separate AP and RS radioresources, see Figure 3-17 and Figure 3-18. At all devices transmit and receive frequencies are separatedby large duplex distance to reduce the self-interference with a single antenna system. Terminals must beable to transmit and receive on both the high and low carriers.APMTfreq. pair 1 freq. pair 2T1R4R2T3APhigh carriers (HC)HC14LClow carriers (LC)RSR1 T4 R3 T2RSLC2 3HCMTFigure 3-17: Scheme H: Multi hop forwardingfrequencyAP RS MTT1R1R3T3Hop 1 Hop 2T2R2R4T4time time timeFigure 3-18: Hops are divided by means of frequency and up- and downlinks are separated byfrequency divisionThe case depicted in Figure 3-18 is characterised as follows:1) As with the Scheme F the RS switches up-and downstream traffic from low to high carriers and viceversa (R1->T2 or R3->T4). The difference here is that the RS has a separate set of carriers andTDMA are replaced with FDMA. The interference conditions are the same.2) It is assumed that the RS cannot transmit and receive simultaneously on adjacent carriers. Theyrequire a greater duplex distance between carriers used for Tx and Rx.3) MTs need to have band-switching capabilities6) The following duplex scheme combinations are used:a) AP: pure FDDb) RS: pure FDD and band switched FDD Hybridc) Relayed MTs: band switched FDDPage 44 (121)

WINNER D2.5 v1.03.4.9 Conclusion on duplex schemes for multi hopFrom the above descriptions and analysis, it seems that TDD based multi hop systems described inschemes A and B exhibit the least differences in behaviour when used in single hop and multihopsystems. Furthermore, there is no need for band-switched equipment or duplex filters in the MT. In B theRS might need band-switching capabilities, depending on how the scheduling is done.The scheme D uses FDD in terminals and FDD +band switched FDD in the RS, as well as duplex filtersin all types of equipment.The schemes C and E enable Half Duplex FDD operation at the MT, although band switching is neededin the RS.The schemes F and H seem less attractive since they rely on band switching capabilities in the userequipment. (A possibility could be to always have an even number of RSs, to allow for MTs withstandard band configurations.)In all cases the traditional roles of ‘uplink’ and ‘downlink’ are blurred, and difficulties might arise whenhandling interference scenarios.It is important to choose a scheme that enables MTs with low complexity in single-hop operation as wellas in multi-hop situations.Taking into account all of the above, multi hop solutions schemes A and B based on TDD seem to befavourable, although there might be interference and coordination issues that needs to be further studied.Some are addressed chapter 4.It should be noted that the IEEE802.16 standard [IEEE802.16] uses a scheme that is very similar toscheme A above, where the phase in which forwarding to/from the MT is completely under the control ofthe RS, and during which time the AP is simply idle.3.5 Combinations duplex methods/multiple access schemeIn this section some basic combinations of UL/DL multiple access schemes with duplex schemes areinvestigated. Since there seems to be a consensus regarding the DL scheme around an OFDM (or at leasta multi carrier, or MC, based) DL scheme, only this DL alternative is considered below. For the UL bothMC and single carrier (SC) based solutions are considered.One of the main reasons for having an UL scheme that differs from the OFDM DL, is that OFDM has ahigh peak-to-average ratio (PAR) which put large demands on the terminal power amplifier linearity,alternatively requires a power back-off that reduces the UL coverage. Therefore, schemes with a smallerPAR are preferred.The TDD and Half Duplex FDD based schemes have the advantage that much of the RF functionality canbe switched off when not transmitting or receiving in order to save power, which is especially importantfor the MTs. A continuous FDD based scheme does not have this advantage.One advantage of TDD is the possibility in some situations to exploit channel reciprocity for e.g. betterallocation strategies or beamforming. It would seem that having essentially the same signalling in the ULand DL would simplify channel estimation since measurements can be made on a per sub carrier basis,while for other SC-based UL schemes some signal processing is necessary. However, the amount ofsignalling processing is likely moderate in comparison to decoding and other operations. Of course, insome UL schemes like IFDMA and FDMA only a part of the spectrum is used and hence the AP canextract information only about this part. Having spectrum wide pilots transmitted at certain intervals cansolve this.Another reason why the choice of duplex method and the choice of multiple access method could beconnected is that interference characteristic experienced by the AP, RS or MT is connected to the choiceof duplex method. A TDD or Half Duplex FDD based scheme is inherently more ‘bursty’ than acontinuous transmission FDD system. However, regardless of the duplex method, the traffic is expectedto be quite bursty anyway since it most likely very packet oriented.This means that the air interface must be able to handle ‘bursty interference’ anyway within limits. Ofcourse, in the case of uncoordinated TDD cells the level of interference can probably be significantlyPage 45 (121)

WINNER D2.5 v1.0higher than for coordinated TDD or the FDD or Half duplex FDD schemes. In that case, the air interfaceand radio parts must be designed to cope with occasionally very high level of interference.3.6 Support for asymmetric aggregated capacityAlthough ‘asymmetric’ capacity is not a ‘technology’, it is logical to treat it in this section since there is aconnection to duplex in some situations.Only the asymmetric aggregated capacity potentially has a strong connection to duplex. On a per user orper service basis, virtually any degree of asymmetry can be obtained regardless of duplex method. Forexample, for a certain service and user 1024 OFDM sub carriers may be allocated on one link and onlyone sub carrier in the other link giving an per user asymmetric capacity ratio of about 1000. Thus, on theper-user or per-service level, asymmetric capacity is only a question of resource allocation (time,frequency, code, etc).However, if the aggregated traffic is considered for the entire spectrum allocated to, say, one operator it isanother matter. Whenever the total traffic in one link (the bottleneck link) has expended all resources forthat link, and still more traffic for that link arrives, the system would benefit from increasing the capacityin that link.One approach is to increase the absolute capacity for the bottleneck link by applying more complex signalprocessing solutions (modulation, MIMO, interference suppression, multi user detection, schedulingtechniques…) for that link. The details of these techniques are outside the scope of this document sincethey are not directly related to the choice of duplex, and can be applied regardless of the choice of duplex.However, if MIMO makes use of channel reciprocity then TDD based schemes are preferredAnother approach that can only be applied in TDD or Half Duplex DD based systems is to increase theactivity factor for the bottleneck link and thus increase the relative capacity in that link over the other(and within limits also the absolute capacity). This, however, necessarily implies a reduction of thecapacity and available range of services on the other link so care must be taken not to make this link anew bottleneck. However, this is not a problem if the asymmetry reconfiguration can take place on a rapidbasis.. The interference problems that arise between cells and between adjacent carriers if the UL/DLcoordination differs are treated in Chapter 4.Only for TDD can the total capacity asymmetry principally be changed by changing the activity factor(the interference situation must be taken into account).For FDD and Half Duplex FDD based systems, the spectrum allocations are more or less fixed oncedecided. On a per user or per cell level, there might be a possibility to hand over to say a wider DL carrierin order to increase the per user or per cell DL throughput, but on an aggregate level this does not solvethe total capacity problem. Unless additional spectrum is available, any capacity problem has to behandled by signal processing or a more densely deployed network.3.7 Control OH/protocol issues3.7.1 Common DL channelsFor TDD by definition the DL has to be silent during periods the UL is active. This means that forexample signals for Cell acquisition and time/frequency synchronization must cease to be transmitted.This also applies to other broadcast channels. Although this is not a fundamental issue it might beconvenient for initial synchronization or cell identification purposes if the synchronization signal isalways present. For FDD or Half Duplex DD based schemes, this possibility is open.3.7.2 Power controlIn TDD based systems open loop power control is a possibility while for FDD, closed loop power controlis needed.3.8 Cell sizesIn order to accommodate for the propagation delay and avoid switching point slot collision, TDD basedsystems need a time alignment mechanism that is activated sufficiently often to track the movement of theMT. The further from the base station, the larger the time misalignment can be, hence the guard periodsmust be designed to cope with a maximum cell size.Page 46 (121)

WINNER D2.5 v1.0FDD based systems does not necessarily need such mechanisms. This is a drawback for TDD basedsystems, in large cell scenarios, but most likely it is minor drawback for a well-designed system.Page 47 (121)

WINNER D2.5 v1.04. Interference management considerations4.1 Interference Scenarios4.1.1 Self InterferenceThis kind of interference affects only duplex schemes where a device (AP or MT) is transmitting andreceiving at the same time. Table 4-1 shows which of the duplex schemes considered in this documentand suffer self interference.Table 4-1: Duplex Schemes Suffering Self InterferenceDuplex Scheme Access Point Mobile TerminalPure FDD Yes YesHalf Duplex FDD Yes NoPure TDD No NoUL / DL Oriented Hybrid Yes In some modesDual Band TDD Hybrid No NoBand Switched FDD Hybrid Yes NoNote that code division duplex (CDD) is not considered in this document due to the complexity involvedin dealing with the high levels of self interference inherent in such a system. See section 5.2.6“Complexity of CDD”.For FDD-based duplex schemes, the transmitter and receiver can be sufficiently decoupled using a duplexfilter. The additional complexity incurred by this requirement is evaluated in section 5.2.7.1.receiver~duplex filter~transmitterFigure 4-1: Duplex Filter at a Mobile Terminal Operating in Pure FDD4.1.2 Co-Channel InterferenceCo-channel interference is, in non-shared spectrum, an intra-operator issue. There is no possibility todifferentiate between wanted and unwanted received signals except in code or geometric space.Interference management must be taken into account when planning a network.For systems operating in shared spectrum it is necessary to make measurements on the resources that asystem intends to use before allocating those resources to a radio link.4.1.3 Adjacent Channel InterferenceAdjacent channel interference protection is dependent on a number of factors:• The out-of-band emissions from the interfering transmitter that are in the wanted signal bandwidth• The channel selectivity of the receive filter• Minimum coupling between the transmitter and receiver4.1.3.1 DLDL and ULUL InterferenceInterference from DLDL (APMT) and ULUL (MTAP) is present for all duplex schemes. Theseinterference types are shown in Figure 4-2.Page 48 (121)

WINNER D2.5 v1.0Cell-BCell-BCell-ACell-AUL UL Interference DL DL InterferenceFigure 4-2: UL UL and DL DL Interference ScenariosThis is a problem well known in cellular systems, and interference can be controlled by network planning,co-location of different operators’ APs and uplink power control. Co-location of operators’ APs limits the“near-far” problems where an MT is positioned close to an interfering AP while being affiliated toanother, distant AP (see Figure 4-3)AffiliationInterferenceFigure 4-3: Near-Far Interference Problem4.1.3.2 ULDL InterferenceThis type of interference occurs between MTs associated with different, uncoordinated cells.If both MTs are using FDD based duplexes (i.e. pure FDD or half duplex FDD) then due to the duplexdistance the interference can be sufficiently dealt with by the receive filter and the out-of-band emissionlevels of the transmitter.If one or other MT is using a TDD based duplex in a band (i.e. pure TDD, DL/UL oriented hybrid, dualband TDD hybrid or band switching FDD) then there is a possibility that a mobile will be receiving at thesame time as a nearby mobile is transmitting in the same band.Cell-BCell-AFigure 4-4: UL DL Interference ScenarioThis type of interference can also occur between MT and RS. These cases will be discussed separately insection 4.2 “Interference Scenarios for Multi-hop and Ad-hoc”.Page 49 (121)

WINNER D2.5 v1.0Due to the mobility of the terminals, this kind of interference represents a statistical process. However,this interference may become serious when two MTs happen to be close to one another. As aconsequence, a high outage probability may occur for those mobiles. The decoupling achievable byreceiver filtering and out-of-band emissions requirements is evaluated in chapter 5. An alternative is touse time slot hopping (section 4.3.1.2) to prevent two nearby mobiles from consistently interfering witheach other, or to use measurements from the AP and MT when allocating resources for a link to avoid thistype of interference (section 4.3.2).4.1.3.3 DLUL InterferenceThis type of interference occurs between APs of uncoordinated cells.If both APs use FDD based duplexes (i.e. pure FDD or half duplex FDD) the interferer will besufficiently separated in frequency from the wanted signal such that receiver filtering and out-of-bandemission requirement specification are realisable such that interference is dealt with sufficiently.However, if one or other AP is using a TDD based duplex in one of its bands (i.e. pure TDD, DL/ULoriented hybrid, dual band hybrid or band switching FDD) then for uncoordinated APs, one AP will bereceiving at the same time as the other AP is transmitting in the same band.Cell-BCell-AFigure 4-5: DL UL Interference ScenarioIn section 4.1.3.1 it was suggested that to limit problems with inter-operator ULUL and DLDLinterference APs for different operators should be co-located. Clearly this is the worst case for DLULinterference. By careful positioning of receive antennas the minimum coupling loss can be increased from30dB to 45dB, however the receive filter and transmitter out-of-band emission requirements areunrealistic from a complexity point of view. This is discussed further in section 5.3.For the intra-operator case where interfering APs are separated, there is still an issue with DLULinterference between uncoordinated cells. Due to their height, APs will often have line of sight radiopropagation between them. This, coupled with high transmit powers, produces high levels of interferenceat the victim receiver.This problem is studied further in section 4.5.4.2 Interference Scenarios for Multi-hop and Ad-hocThis section emphasises on the interference management in infrastructure oriented “Multi-hop networks”with homogeneous air interface that consists of a fixed deployment of network operator owned APs andRSs. The fixed RSs extend the coverage of the core network access points (APs), in order to reduce thenumber of APs and in consequence cost. The deployment of RSs instead of APs is a trade-off betweendeployment and maintenance costs and network capacity.The alternative network architectures are first shortly addressed in1) Interference scenarios in “ad-hoc networks”in 4.2.12) Interference scenarios in a “Multi-hop network” with fixed relay stations and a heterogeneous airinterface in 4.2.2Page 50 (121)

WINNER D2.5 v1.04.2.1 Interference scenarios in “ad-hoc networks”Depending on the network architecture of Mobile Ad hoc networks (MANETs) different interferencescenarios arises.The architecture can be classified into cluster-based networks with centralised MAC (e.g. Hiperlan/2,Bluetooth) and those with distributed MAC (e.g. 802.11 DCF) [Adhoc]. In the centralised case there are aset of special nodes, so-called cluster heads, which schedule the transmissions of all nodes in its range. Inthe distributed case all nodes schedule their transmissions in coordination with all other nodes under therules of a given distributed MAC protocol.The interference scenarios in centralised ad-hoc networks are similar to that of multi-hop networks with ahomogeneous air interface addressed in section 4.2.3 (except for the point that there is no trafficconcentration towards APs). The interference scenarios arising in a “distributed ad-hoc network” isshortly addressed in the following sub-section.4.2.1.1 Distributed Network ArchitectureAt MANETs with distributed network architecture all stations perform the same distributed MACprotocol to access the wireless medium with a built-in interference avoidance strategy (except ALOHA).All data transmission and reception has to be in the same frequency band since there are no special nodesto translate the transmission from one frequency band to another. Therefore all ad hoc networks operate inTDD mode [MacSurvey].As there are no channels assigned to different cells or “clusters”, because there are no, there is inconsequence also no co-channel interference in its original sense. The CCI has its counterpart in the“Hidden Node” and “Exposed Node” problems (refer e.g. to [MacSurvey]) at which either• a sending station allocates the medium although the receiver is interfered by a 3 rd nodestransmission not sensed by the sending station (“Hidden Node”), or• a station back-offs from sending, because of sensing a busy channel, although a destined receiverwould be able to correctly receive the transmission(“Exposed Node”).The classification of ACI interference scenarios in terms of UL and DL does not apply here since allnodes are considered mobile and a geographical separation between a class of nodes (fixed APs or RSs),which is basis for this partitioning of radio resources into UL and DL, can generally not be assumed.Collisions due to a severe ACI, i.e. transmissions on adjacent carriers nearby a receiving station, can beavoided by a feed-back signaling from the receiving station to the sending station either with a controlhandshaking or an out-of-band signaling ([MacSurvey]).4.2.2 Interference scenarios in a “Multi-hop network” with fixed relay stations and aheterogeneous air interfaceA “Multi-hop network” using a heterogeneous air interface, i.e. the radio links between network elementsutilise fixed wireless access (FWA) beams, form a mesh or a point to multi-point network as e.g. in ETSI-BRAN-HyperAccess [HypAcc] or in IEEE 802.16 [IEEE802.16]. When the relay-links do not have anyimpact on the AP/RS-MT air interface the duplexing techniques and their interference management atboth air interfaces can be preformed independently from each other. The (AP/RS)-to-MT air interfacedoes not differ from that of a normal cellular network with just AP and MT devices. This case isaddressed in sections 4.3ff.4.2.3 Interference scenarios in a “Multi-hop network” with fixed relay stations and ahomogeneous air interfaceThe interference management of “Multi-hop networks” with fixed relay stations have great similarities tothat of a cellular network, so that concepts of interference management between AP and MT type nodescan be extended to the multi-hop case. AP and RS type nodes have many similarities as e.g. with respectto mobility, acceptable complexity, traffic aggregation:1) Both AP and RS type nodes are power unlimited devices and thus can be more complex than powerlimited MTs. They may havea) multiple antennas and use beam-forming or MIMO techniques for spatial multiplexing orinterference avoidance,b) multiple receiver and transmitter chains to support more complex duplex schemes,c) complex duplex filters for self interference avoidance or to support FDD band switching andPage 51 (121)

WINNER D2.5 v1.0d) take over medium access control and traffic routing function (centralised MAC scheduling).2) The set of APs and RSs are installed apart from each other with a pre-calculated distance to serveMTs within a specific geographical area. There are 2 possibilities to extend the term “cell” to “multihopnetwork” case. The second case (b) is used in this chapter:a) The cell is the geographical area of an AP that allows MTs to access the core network eitherdirectly or via one or more RSs with the help of this AP.b) The cell is the one hop communication range of an AP or a RS.The main differences to traditional cellular networks are that the RS and AP nodes need to be incommunication range to enable the relaying. This has the following impacts:1) Either the multi-hop cells are overlapping stronger or the RS-RS or RS-AP links make use of higherantenna gains and can reduce other sources of interference.2) While a RS or AP is transmitting an addressed AP or RS need to be able to receive on that resourceunit defined by time, frequency. Since CDD is considered not practical, there can be no continuoustransmission at APs and RSs, excepta) for the case that a RS has 2 sets of transmit and receive antennas that are physically separatedand shielded against each other orb) a FN concept is used as detailed in section for the forwarding scheme H.3) AP and RS or RSs are deployed in a distance that allow for a sufficiently high data rate. Whereas thetarget SINR at the cell boarder (e.g. SINR=15dB) defines cell radius R and the distance between 2APs (roughly two time R) , the cell radius of APs and RS:s may be defined by the required linkquality of the AP-RS and RS-RS links (target SINR=15-20dB?). The deployment of AP and RSdevices is denser than that of a traditional cellular network. With more complex devices, the linkquality between fixed network elements can be made better than towards MTs.In chapter 4.1 the different interference scenarios are listed, which are repeated here to extend it to themulti-hop forwarding schemes A to H introduced in section 3.4.4.2.3.1 Self InterferenceAs can be seen from the different relaying schemes of section 3.4 a RS has to serve at least 2 radio linksresulting in a combination of basic duplex schemes. Self interference occurs when a device is transmittingwhile simultaneously receiving. This occurs at the cases marked with a “yes” and with greyed cells withinthe table below. The AP and MT columns repeat just the information already provided in Table 4-1.Table 4-2: Duplex and Forwarding Schemes s Suffering Self InterferenceMuli-hopforwardingschemeRelay Station Duplexscheme Access Point Mobile TerminalA 2*TDD/no TDD/no TDD/noB 2*TDD/yes TDD/no TDD/noC 2*Half duplex FDD/no Half duplex FDD/no Half duplex FDD/noD 2*(T+F)DD/yes FDD/yes FDD/yes 1)E 2*TDD/no Half duplex FDD/no Half duplex FDD/NoF 2*Half duplex FDD/no half duplex FDD/noBand switched Halfduplex FDD/No 2)G FDD+TDD/yes FDD/yes TDD/noHFDD/yesFDD/yesBand switchedFDD/yes 2)Notes:1) A half duplex FDD variant with no self interference is also possible here: Within slot 2 the RS mayuse a half duplex FDD scheme (see section 3.4.4).2) The MT switches the Rx/Tx frequencies when selecting another AP or RS.Page 52 (121)

WINNER D2.5 v1.0access network otherwise. It is beneficial when the clustering scheme also defines the deployment schemeof APs and RSs. Two examples for assignment of APs and RSs to cells might be:• One AP per cluster: The cells numbered 1 in Figure 4-6 get assigned an AP (A.1,B.1,C.1) andthe surrounding 6 cells at each cluster are assigned to RSs.• One AP every 2 nd cluster: The cells numbered 1 in cluster A (A.1) and C (C.1) do have an APand all others are RS-cells.The following section lists the minimum, worst case distances between an AP or RS and a MT, which isbasis for network planning:4.2.3.2.2 Interference typesThe mobility of MTs is basis for the classification in different interference types. Ignoring here the caseof sectored cells, APs and RSs can be assumed to be located in the middle of their cell and mobiles arestatically uniform distributed within a radius R. APs and RSs are in a minimum distance of 2 times cellradius, assuming minimal overlapping of cells. Using the free space path-loss model, with gamma=2 anda 7 cell clustering scheme with D=4.58 R the following worst case CIR values due to CCI can becalculated:Table 4-3: CCI on RS/AP to MT radio linksAP/RSMTCo-channel AP/RS interfererD (Static)DL-UL: CIRmin=PL(R)/PL(D)=13dBD-R,Stochastic range [D-R,D+R]UL-UL:CIRmin=5.54 dBCo-channel MTinterfererD-R,stochastic range [D-R,D+R]UL-UL:CIRmin=5.54 dBD-2R,stochastically range[D-2R,D+2R]UL-DL:CIRmin=4.12 dBThe table above does not include CCI scenarios caused by transmissions on relay radio links. This type ofinterference may be even more severe, detailed below. The following simplified deployment scenario(street deployment, Manhattan scenario) depicts the issue. At this scenario it is assumed that every 3 rd cellre-uses the same network resource, which is similar to the 2-dimensional 7 cell clustering scheme. The reusedistance and cell-radius quotient is thus D/R=6.Page 54 (121)

WINNER D2.5 v1.0DCulprit12RCulprit2Victim1Victim2Victim3AP RS RS AP RS6R8R4R4R6R2RCo-channelcellvictim cellFigure 4-7: Issue of linear arrangementIn Figure 4-7 the victim and interfering co-channel cells are arbitrarily selected to be AP-cells. Theinterference scenarios would be the same, if a RS-cell would have been selected. I.e. the interferences areindependent on whether traffic is UL or DL.The table below summarises the node distances and lists the associated CIR values derived with a freespace path-loss function. Note that the interfering transmissions are assumed all to be performed on theco-channels cell resource.Table 4-4: CCI on relay linksVictim1Victim2Victim3Culprit 1 Culprit 24Ropposite directionCIR=PL(2R)/PL(4R)=6dB6Rsame directionCIR=9.5dB8Rsame directionCIR=12dB2Ropposite directionCIR=0dB4Ropposite directionCIR=6dB6Ropposite directionCIR=9.5dBThis CIR values may not allow for a HDR communication with a high modulation scheme, which isdesirable since RSs aggregate traffic of multiple MTs. Further means are needed to improve these values.The following techniques may be applied to avoid interference and low CIR values:• In those cases where the data-signal and the interfering signal are sent into opposite directionsbeam-forming (i.e. rx/tx antenna gains) can solve the issue. This is when Victim1 or Culprit2 areinvolved.• Every RS/AP sends only in its assigned resource instead of the receiver’s resource. This avoidsthe CCI interference scenario Culprit1->Victim2.• The interference scenario Culprit1->Victim3 with relative high distance ratio 8R/2R (12dB) canbe not that easily avoided: Methods can be:o The stations are deployed so that they get shadowed by environment (below roof-top).Page 55 (121)

WINNER D2.5 v1.0o Directional antennas, if the stations are not on a straight line.o A clustering scheme with more cells per cluster and a higher partitioning of the networkresource.o In addition to orthogonal channels in time and frequency, CDMA techniques might beused to decouple data-signal from interference.4.2.3.2.3 Interference produced by relayed trafficFigure 4-8 below depicts that a single transmission is replaced by two transmissions. If the 2 transmissionare sent with lower power or with the same power, but higher data rate and thus shorter time, theproduced interference at neighbouring cells can even be smaller in the 2-hop case. This is especially thecase if the direct path is shadowed by environment and NLOS is replaced by 2 times LOS conditions.RSRSAPAPdownlinkuplinkFigure 4-8: Single-hop vs. multi-hop interferenceThe transmission on the relay-link suffers from a path-loss of 2 times the cell radius. This higher path-losswould need to be compensated e.g. by antenna-gains or a more complex signal processing, so that the MTcoverage (cell radius) is half the distance between AP and RS. Note that a simple MT with only oneantenna would send omni-directional, whereas the RSs and APs are equipped with multiple antennas.4.2.3.2.4 Inter Cell Channel MultiplexingIn chapter 3 forwarding schemes A-H are introduced and described at the example of a single AP, RS andMT. In order form a cellular network every AP may have multiple associated RSs to relay MTs traffic indifferent directions.For the example of the 7 cell/cluster scheme depicted in Figure 4-6 7 orthogonal channels for the AP andits 6 RSs are needed. The RS-cell channels might be multiplexed using any of the known schemesTDMA, FDMA and CDMA. Due the limitations of simultaneous transmission and reception only theTDMA scheme does not restrict to uplink and downlink connections. Two MTs without the involvementof the AP might communicate in a distributed fashion: E.g. MT1RS1RS2MT2. If relaying isrestricted to upstream and downstream, RSs do not need to communicate with each other. This allows fora FDMA scheme or CDMA scheme.4.2.3.3 Adjacent Channel InterferenceThe following sections lists some interference scenarios for all forwarding schemes A-H introduced inchapter 3. ACI occurs when adjacent frequency channels exists. For that reason an additional connectionis introduced. To simplify the figures it is between the AP and a second MT (at scheme B it is a secondRS). The same interference scenario would also occur, if that MT would be associated to another colocatedAP- or RS-cell.The interference scenarios already listed in section 4.1 do also occur but in some cases with a differentmapping to UL and DL, when a relay link (AP-RS or RS-RS) is involved. With a re-definition of thetraditional meaning of UL and DL in the context of interference scenarios and multi-hop this mismatchcan be resolved: Each AP or RS that serves MTs in its assigned cell has also assigned a specific radioPage 56 (121)

WINNER D2.5 v1.0resource. This resource is partitioned into an “UL channel” and a “DL channel”, depending on whether aAP/RS is sending or receiving in its assigned radio resource:.a) UL’: AP/RS receives on its assigned UL channel.b) DL’: AP/RS sends on its assigned DL channel.With this re-definition the interference scenarios of section 4.1 also apply here with the generalisation thatthe depicted cells can be both AP- of RS-cells and the APs and RSs also establish links with each other.E.g. when a RS sends to an AP the direction is UL in the traditional meaning, but it sends in directionDL’ when it sends on its assigned “DL channel”. Nevertheless the figures depicted in the following subsectionsuse to the original definition to be in-line with sections 2.2.1 and 3.4.4.2.3.3.1 Forwarding scheme ARSAPT2/DLfrequencyT1/DL R4/ULT/DLR/ULAPR/ULDL->UL interferenceworst distance=2RtimefrequencyRSR1/DLT4/UL T2/DL R3/ULR/ULAPT4/ULRST3/ULtimeR/DLULDL interferenceworst distance=RfrequencyR/DLR2/DLT/ULT3/ULMT1MT2RSR2/DLtimeAPT/ULUL->DL interferenceworst distance=>0Figure 4-9: Scheme A ACI scenariosThe different UL/DL switching points at the 2 RF channels cause various interference types. The MT-MTinterference is the worst case in this scenario. To avoid all three depicted ACI interference cases theUL/DL switching points would need to be aligned. Instead of one DL and one UL periods for the AP-MTradio link there would be the need two of each aligned with the others.Page 57 (121)

WINNER D2.5 v1.04.2.3.3.2 Forwarding scheme BfrequencyT1APR4frequencyR1RSesT4frequencyMTsT2/DLR3/ULR2/DLT3/ULT2/DL R3 R2/DL T3timetimetimeRSRSR3/ULT3/ULRSRST2/DLDL->UL interferenceworst distance=RR2/DLDL->UL interferenceworst distance=0Figure 4-10: Scheme B ACI scenariosThis use case in this scenario is that different channels of RS-cells are FDMA multiplexed and at each RFchannel TDD is used with variable switching point. This causes the known interference types as in thepure TDD duplex case. This might be avoided e.g. by• not selecting adjacent channels at adjacent cells or• not assigning crossed slots to MTs near the cell boarder.Page 58 (121)

WINNER D2.5 v1.04.2.3.3.3 Forwarding scheme CHop 1 Hop 2frequencyT1APT5R6R4frequencyR1RST2timeT4R3frequencyMTsR2R5timeT3T6Figure 4-11: Scheme C: ACI scenariostimeAt scheme C there are no ACI interference scenarios, with normal Tx/Rx mapping.Page 59 (121)

WINNER D2.5 v1.04.2.3.3.4 Forwarding scheme DfrequencyAP RS MTsT1/DL R1/DL T2/DL R2/DLT/DLR/DLAPT/DLR1/DLR/DLRST2/DLDL->DL interferenceworst distance=RR4/ULT4/ULR3/ULT3/ULR/ULT/ULT4/ULRSR3/UL0 00timeAPR/ULUL->UL interferenceworst distance=RFigure 4-12: Scheme D: ACI scenariosScheme D may cause ACI in case of co-located cells, where the second MT which is associated to the APis very near to the RS. This highlights the need for separate non-overlapping RS- and AP-cells.4.2.3.3.5 Forwarding scheme EfrequencyAP RS MTsT1/DL R1/DL T2/DL R2/DLT/DLR/DLAPT/DLR1/DLR/DLRST2/DLDL->DL interferenceworst distance=RR4/ULR3/ULT4/ULT3/ULR/ULT/ULT4/ULRSR3/UL0 00timeAPR/ULUL->UL interferenceworst distance=RFigure 4-13: Scheme D: ACI scenariosScheme E is identical to scheme D in respect to ACI.Page 60 (121)

WINNER D2.5 v1.04.2.3.3.6 Forwarding scheme FfrequencyAP RS MTsT1/DL R1/DL R3/UL T3/ULT/DLR/DLAPT/DLR1/DLR/DLRST3/ULDL-DL interference at 2RandUL->DL interference atworst distance=0R4/ULT2/DLT4/ULR2/DLR/ULT/ULRST2/UL0 00timeAPT/ULR2/DLDL->UL interference at 2RandUL->DL interference atworst distance=0Figure 4-14: Scheme F ACI scenariosDue to the opposite mapping of Rx/Tx at MTs there is a high potential for severe interference due to MT-MT interference. This mitigates a main advantage of the underlying FDD duplex scheme. A method toavoid this type of interference would be that MTs get relayed by always an even number of relay stations.Page 61 (121)

WINNER D2.5 v1.0frequencyAP FN RSMTsT1/DL R1/DLT3/DL R3/DLR5/UL T5/ULT/DLR/DLR6/ULT6/ULT2/DLR2/DLR4/ULT4/ULT/ULR/UL0 000timeR5/ULRST5/ULRSR4/ULT6/ULAPFNT3/ULAPFNR/ULR/ULT/ULT/DLDL-UL interference orUL->UL interference atworst distance=RUL->DL or UL->ULinterference at worstdistance RFigure 4-15: Scheme F with 2 relay stationsAt this variant of scheme F there are much less severe ACI interference scenarios. The forwarding node(FN) just relays traffic between a RS and an AP which serve MTs. In this way all APs and RSs have thesame mapping of Rx/Tx to DL and UL carriers and also all MTs do have the same mapping as in legacyFDD networks.Page 62 (121)

WINNER D2.5 v1.04.2.3.3.7 Forwarding scheme GfrequencyAP RS MTsT1/DL R1/DLT/DLR/DLAPT/DLR1/DLRST2/DLDL->DL or DL-ULinterference atdistance=2RT2/DLR3/ULR2/DLT3/ULR4/ULR/ULT4/ULT/ULT4/ULRSR3/UL0 00timeR/ULAPT/ULUL->UL interferenceworst distance=R andUL-> UL interferencefrom interferer indistance 2R.Figure 4-16: Scheme G ACI scenariosScheme G is identical to scheme D in respect to ACI.4.2.3.3.8 Forwarding scheme HfrequencyAP RS MTsT1/DLT/DLR1/DLR/DLR3/UL T3/ULAPT/DLR1/DLR/DLRST3/ULDL-DL interference at 2RandUL->DL interference atworst distance=0R4/ULT4/ULR/ULT/ULT2/DLR2/DLRST2/ULAPR2/DL0 00T/ULDL->UL interference at 2RandUL->DL interference atworst distance=0Figure 4-17: Scheme H ACI scenariosScheme H is identical to scheme F in respect to ACI: There are severe MT-MT interference risks. As inscheme F the FN concept can solves this issue.Page 63 (121)

WINNER D2.5 v1.0frequencyAP FN RSMTsT1/DLR1/DLT/DLR/DLT3/DL R3/DLR5/ULT5/ULR6/ULT6/ULR/ULT/ULT2/DLR2/DLR4/ULT4/UL0 000timeT6/ULAPR5/ULFNRST3/ULAPT2/DLFNRST3/DLR/ULT/DLDL-UL interference orUL->UL interference atworst distance RT/ULDL->DL or UL-DLinterference at worstdistance RFigure 4-18: Scheme H with 2 relay stationsThe figure above shows up more arrows of potential ACI interference. This is because a FDMAforwarding scheme is used here. Only some of them are detailed at the bottom and all these are not assevere as with the MT-MT interference scenario above, at which MTs have an inversed mapping offrequencies to Rx/Tx.4.2.4 Conclusion multi-hop interference scenariosThe conclusions listed below apply to the case of Multi hop networks with homogeneous air interfacewith fixed relay stations since only this is detailed in this section 4.2.1) The self interference at the RS depends on how the duplex schemes of both links are combined. Theforwarding schemes A, C, E and F do not suffer from self interference and whether this is an issuedepends on the acceptable RS complexity.2) Concerning co-channel interference there is the general issue that relay-links need to have a highertransmission range compared to the cell size of the APs or RSs. This may require a higher re-usefactor.3) The different classifications of interference scenarios introduced in section 4.1.3 also apply in thecontext of multi-hop, but only with a re-definition of the traditional meaning of UL and DL. Besidethe end-to-end meaning (APs MTs), the terms “UL” and ”DL may also be interpreted locally foreach AP/RS-cell:a) UL’: AP/RS receives on its assigned UL’ channel.b) DL’: AP/RS sends on its assigned DL’ channel.4) To reduce CCI caused by transmissions on relay links the following methods should be obeyed:a) APs or RSs should send on its assigned DL’ channel.b) FNs receive on DL’ channels of the sending AP/RS and send on the UL’ channels of thereceiving RS/AP.5) When using a TDMA scheme for defining channels to neighbouring cells all neighbouring APs andRSs can communicate with each other. All schemes except scheme H utilise TDMA. In all cases, analignment of the switching points between these UL and DL channels on adjacent carriers wouldavoid UL’-UL’ and DL’-DL’ ACI. An alignment in time requires that these AP/RS-cells are framesynchronised.Page 64 (121)

WINNER D2.5 v1.06) It is also possible to use a FDMA or a CDMA multiplexing schemes to separate AP/RS-cells, but inthis case FNs are required that relay traffic between AP/RS-cells. Otherwise MTs would need to havebandswitching capabilities and there would be a severe MT-MT interference issue as depicted forscheme H in Figure 4-17.4.3 Approaches to Interference ManagementThere are two approaches that can be taken when managing interference for a cellular system:interference averaging and interference avoidance.4.3.1 Interference AveragingThe ethos behind interference averaging is that every receiver in a cell will see the minimum amount ofinterference from users in its own cell, but every receiver should see an equal amount of interference fromtransmitters in other cells.There are a number of techniques to average interference between cells• Frequency hopping• Time slot hopping• Spreading• There is also some averaging which comes about as a result of statistical multiplexing of packet data.4.3.1.1 Frequency HoppingFrequency hopping is a technique that has been used successfully in narrow band cellular systems (e.g.GSM). The technique assumes that the multiple access scheme has a frequency component. Thefrequency of a link is changed on a frame-by-frame basis picked from a set of frequencies using a pseudorandomsequence.FrequencyFigure 4-19: Frequency HoppingThis averages adjacent channel interference between cells and leads to capacity benefits.In Orthogonal Frequency Division Multiple Access (OFDMA), frequency hopping can be implemented assub-carrier hopping.Time4.3.1.2 Time Slot HoppingTime slot hopping uses the same basis as frequency hopping (section 4.3.1.1), averaging the interferenceseen from links in another cell. This technique is of course only applicable for a system using a TDMAstructure.Page 65 (121)

WINNER D2.5 v1.0FrameFigure 4-20: Time Slot HoppingTime slot and frequency hopping can be combined; however using both techniques will not necessarilygive significant gain over using a single technique.For a single carrier system, time slot hopping may be a less complex solution than frequency hopping.However, in a multi-carrier system the complexity will be more or less comparable.Time4.3.1.3 SpreadingSpreading can be used to allow the cells in a cellular network to effectively share a number of frequencychannels. This averages the interference seen from the other cells. This technique may also be used incombination with time slot hopping.Walsh codes are used extensively in CDMA systems including UMTS. They have good cross- and autocorrelationproperties when synchronised. But when a timing offset is introduced the auto-correlation hasa number of peaks (dependant on the code employed) and certain pairs of codes have peaks of high crosscorrelation.Figure 4-21 shows the auto-correlation for a particular 64-symbol Walsh code and its crosscorrelationwith another code.Figure 4-21: Cross and Auto Correlation Functions for a 64-Symbol Walsh CodeA class of spreading code currently being discussed in the literature is Zero-Correlation Zone (ZCZ)sequences (eg. [TOR-04]). ZCZ sequences are designed to have good correlation properties for a range oftiming offsets:L⎧( = )( ) = ∑ − 1P0P0*EP0τ 0RS Pτ sqs( q+τ ) mod L= ⎨( 4-1 )0q=0⎩0( − T ≤ τ ≤ −1,1 ≤ τ ≤ T )RSP0 , SP1L= ∑ − 1qq=0P0P1*( τ ) s s( τ ) = 0 ( − T ≤ ≤ T )q+ mod Lτ( 4-2 )Figure 4-22 shows the cross and auto-correlation functions for a particular set of (64,4,14) ZCZsequences. (The ‘64’ relates to the length of the code in symbols, the ‘4’ relates to the number of codes inPage 66 (121)

WINNER D2.5 v1.0the set and the ‘14’ relates to the size of the zero correlation zone.) The shaded area is the range of timingoffsets for which the sequences maintain their optimal characteristics.Figure 4-22: Cross and Auto Correlation Functions for (64,4,14) ZCZ Sequence SetZCZ sequences do, however, have disadvantages compared with Walsh codes: the number of codesavailable in a set is limited relative to a set of Walsh codes of the same length, also they are multi-phaseand multi-level rather than binary which may impact the peak to average power ratio of the signal.ZCZ sequences could be used in a cellular system to differentiate between signals from different cellswith lower requirements for the synchronisation between cells. Additionally, for TDD systems, a betterseparation of uplink and downlink signals can be achieved for ULDL and DLUL interference cases.4.3.2 Interference AvoidanceInterference avoidance uses measurements to allocate resources for a link based on minimisinginterference for that link. This is a suitable scheme if the correlation between link interference betweendifferent radio resources is low.The complexity in terms of scheduling algorithms and measurement reporting is larger for an interferenceavoidance strategy compared with an interference averaging strategy. Section 4.5 gives an exampleinterference avoidance method for the special case of DLUL and ULDL interference seen in noncoordinatedTDD systems.Within bands of shared spectrum there is an additional complication of sharing spectrum with othersystems without causing undue interference. This involves making measurements of interference andavoiding the reception or production of interference in resources (time, frequency, code space, or space)where other systems could unduly affect performance or be affected.Since interference is not a reciprocal property of a channel there is no advantage to using a TDD basedduplex to minimise measurement reporting. FDD based systems have a slight advantage in terms ofreporting delay allowing faster allocation of resources.The following two sub-sections describe the differences between centralised and distributed approachesto interference. A section on adaptive or switched beam antennas is also included as another method thatcan be employed to avoid causing and receiving interference.4.3.2.1 Centralised Interference AvoidanceA centralised approach to interference avoidance assumes that there is a central, possibly intelligent entityin the network which controls the allocation of resources used for a link. This entity must have knowledgeof the position of APs, possibly also the position of MTs and a model of the interference mechanismsexisting between them.Page 67 (121)

WINNER D2.5 v1.04CRM allocates resourcesbased on knowledge ofallocations made to othercells.CentralisedResourceManagement3AP makes interferencemeasurements and reportsthese and measurementsmade by MT to CRMtogether with a resourcesrequest5CRM signalsallocation ofresources to AP.12MT makes interferencemeasurements andreports to AP togetherwith access requestMT requires newallocation ofresourcesNew callAP6AP signals newallocation ofresources to MT.MT in callMT in callAPMT in callFigure 4-23: Centralised Resource Management4.3.2.2 Distributed Interference AvoidanceIn a distributed architecture an AP will make decisions on what resources to use based on measurementsmade both at the AP and at the MT. It is possible from these measurements to choose resources where thesystem in question will not be interfered with, but this does not guarantee that other cells or other systemswill not be interfered with. This problem has been studied in [HUL-04] and a concept proposed usingbeacons transmitted by a receiver to allow a transmitter to choose a set of resources which will not causeundue interference to another system or cell.4.3.2.3 Adaptive or Switched Beam AntennasAnother method of interference avoidance is the use of adaptive or switched beam antennas. An APequipped with such antennas can limit received interference and minimise interference broadcast to otherusers by only transmitting and receiving signal in the direction of the wanted user.CELL ACELL BFigure 4-24: Interference Avoidance Using Adaptive or Switched Beam AntennasPage 68 (121)

WINNER D2.5 v1.0Switched beam antennas have been used in 2G and 3G systems and have been shown to providesignificant capacity gains ([AHM-00a], [AHM-00b]).A TDD based system can utilise the reciprocity of the channel to reduce the complexity of an adaptive orswitch beam system. FDD systems are unable to make use of this reciprocity leading to slightly highercomplexity at the AP, but the use adaptive antennas is not precluded for an FDD system.Studies (eg. [SCH-03]) have shown that, for UMTS, adaptive beam forming gives system capacity withperformance similar to 60° sectorization if channel estimation is perfect. With channel estimation errorsincluded, performance is closer to 120° sectorization. The trade-offs between adaptive beam forming anda long term spatial solution such as sectorization for a Winner system is for further study.4.4 Conclusions on the Effect of Interference Management on the Choice ofDuplex SchemeThis section has outlined a number of interference scenarios and the impact that the choice of duplexscheme has on them. These impacts are summarised in Table 4-5 below. Of these scenarios the mostdifficult to manage is the case of DLUL interference in a duplex scheme that used TDD in at least oneof its allocated bands (pure TDD, UL/DL oriented hybrid, dual band TDD hybrid and band switchedhybrid). Especially in the case where two operators have co-located APs these duplex schemes cannot beused without co-ordination and synchronisation between operators.Table 4-5: Applicability of Duplex Schemes for Interference ScenariosSelf InterferenceCo- / Adjacent Channel InterferenceAP MT DLDL 2 ULUL 2 DLUL ULDLPure FDD Yes 1 Yes 1 Yes Yes Yes 3 Yes 3Half Duplex FDD Yes 1 Yes Yes Yes Yes 3 Yes 3Pure TDD Yes Yes Yes Yes No 4 No 4, 5UL/DL Oriented Hybrid Yes 1 Yes 1 Yes Yes No 4 No 4, 5Dual Band TDD Hybrid Yes Yes Yes Yes No 4 No 4, 5Band Switched FDD Hybrid Yes 1 Yes Yes Yes No 4 No 4, 5Notes:1. Self interference can be managed by use of a duplex filter.2. DLDL and ULUL interference affects all duplex schemes and can be managed by careful network planning3. DLUL and ULDL interference managed by duplex distance4. For non-coordinated or non-synchronised cells only.5. Interference between MTs may be managed by an interference avoidance scheme.A number of interference averaging and interference avoidance strategies have also been discussed. Noparticular duplex scheme shows any real benefit for any of the techniques discussed. In the case ofinterference avoidance, pure FDD and UL Oriented Hybrid have a small advantage over other schemesdue to the faster round trip signalling times available. On the other hand, Pure TDD or Dual Band TDDmay have benefits when employing smart or switched beam antennas due to channel reciprocity.However, no clear differentiation was found.4.5 Example Interference Avoidance Scheme for TDDThis section uses techniques developed by Jeon and Jeong [JEO-00] to investigate the effects of TDDmodes of interference for a TDMA/CDMA scheme and to compare an interference avoiding slotallocation scheme as described in section 4.5.2 with a random allocation scheme.4.5.1 Allocation of Time Slots in TDDTDD has an advantage over FDD when the ratio of required uplink to downlink data rate is non-static.Applications such as web browsing, file upload and telephony have different uplink-downlink ratioPage 69 (121)

WINNER D2.5 v1.0requirements. TDD is able to change the point in a frame where the link changes from uplink to downlinkthus making maximum use of the available bandwidth.The disadvantage of this scheme is that when two adjoining cells have different service mixes, andtherefore different switching points, interference occurs between uplink and downlink. Slots where thisoccurs are termed crossed-slots.We assume distributed dynamic channel allocation (DCA) of time slots is used on a cell by cell basis andthat cells are separated by a suitable spreading code. Other studies (e.g. [HAA-01]) have considered acentralised approach.This section describes an allocation methodology that can be applied to a TDD system with a TDMAmultiple access component. Although some of the multiple access technologies being evaluated as part ofthe WINNER project are not based on TDMA, in reality all will have some form of time component toseparate users. For example, for OFDMA a user is unlikely to require use of all OFDM transmitted evenwhen using a restricted number of sub-carriers. Users can therefore often be separated in time even ifTDMA is not explicitly used as a multiple access scheme.4.5.2 Description of Allocation SchemeInterference between access points is minimised by allocating crossed slots to the lowest powertransmissions in the cell. That is low rate services or mobiles with low path loss.Interference between mobiles in adjacent cells can be minimised if crossed slots are allocated to mobileswhich will cause the least interference outside the cell, that is: mobiles with low transmit power andmobiles close to the centre of the cell. The received interference power will be dominated by the pathlength rather than by transmit power, therefore in most situations crossed slots will be allocated tomobiles close to the centre of the cell.The probability of a slot in a frame being crossed increases towards the switching point; therefore mobilestowards the edges of the cell should be allocated slots at the ‘ends’ of the frame. Communal channelssuch as broadcast and random access channels should be allocated at the very ends of the frame such thatthey are never crossed.To implement this strategy the access point does not require knowledge of how neighbouring cells haveset their switching point.In addition, access points can monitor interference on its uplink channels, collect measurement reportsfrom mobile stations within its cell and make slot allocations based on the information gathered([WINIR23]) ([HAA-01] presents an approach for a centralised DCA). The following analysis does nottake information from measurements into account but this should be considered for study at a later date.4.5.3 Scenario and AssumptionsThis analysis makes a number of assumptions in order to express the ratio of energy per bit and noise perunit bandwidth (EbNo) in a closed form. The scenario concerns two equal sized, adjacent cells, CELL Aand CELL B, as shown in Figure 4-25. The cells are assumed to be owned by the same operator,synchronised, non-overlapping yet uncoordinated. The arrows show ULDL and DLUL interferencefor mobiles using crossed slots.Page 70 (121)

DWINNER D2.5 v1.0rAKr BCELL ACELL BFigure 4-25: Simplified Scenario Used in TDD Interference AnalysisIt is assumed that all mobiles using crossed-slots are located within the radius rAor rBdepending on theircell affiliation. All mobiles outside these radii do not use crossed-slots.Interference from MTs is averaged over all possible positions that the MT could be in. For example,crossed-slot interference from an MT in Cell A is taken as the average interference from all positionswithin an r A radius of the centre of Cell A.The total number of slots in a frame = N = Nd+ Nc+ Nu. Where N d and N u are the number of uncrosseddownlink and uplink slots respectively. N c represents the number of crossed slots.Figure 4-26 shows how Nd, Nc and Nu define the switching points used in each of the cells. The cells areassumed to be part of the same network and be perfectly synchronised. Note also that CELL A is assumedto use crossed-slots as uplink and CELL B uses those slots for downlink. That is:u uRARBd ≥d( 4-3 )R RABCELL ADLULCELL BDLULNd Nc NuFigure 4-26: TDD Frame Structure for Simplified ScenarioFor simplicity, we assume that a single switching point is used for each of the cells. There is norequirement for this to be the case except that having multiple switching points will impact the efficiencyof the scheme due to increased signalling required for description of the frame structure and losses due totime required for each switching point. Allowing multiple switching points will also require informationto be passed between APs to determine which slots are crossed.4.5.4 Derivation of Equations for Analysis of TDD InterferenceThis section derives general equations for use in the analysis of TDD interference. Sections 4.5.4.1 to4.5.4.6 give details of how the equations are arrived at. Section 4.5.4.7 summarises the results of thissection.Page 71 (121)

WINNER D2.5 v1.0These calculations are based on work in [JEO-00] with some additions and changes. One feature of theexpressions, arising from the UTRA TDD background, is the inclusion of inter-code interference fromother users in the same cell using the same timeslot. This makes up only a small part of this investigationbut the relevant terms are retained for completeness.The notation employed in this section is as follows:D: Diameter of the cells (Cell A and Cell B are assumed equal size)W: Channel BandwidthN C : Number of crossed-slotsN: Number of slots per frameR X U : Uplink data rate per user in Cell X.R X D : Downlink data rate per user in Cell X.I U X : Interference from the uplink of Cell X.I D X : Interference from the downlink of Cell X.r X : Radius within Cell X where mobiles are allocated to crossed-slotsM X : Total number of mobiles in Cell Xm X : Number of mobiles in Cell X allocated crossed slots (related to r X )k: Path loss constantv: Constant defining how path loss increases with distance (assumed equal to 4)P t X : Power transmitted by a mobile distance r X from the centre of Cell XP r X : Power received by the access point from a mobile station in Cell X.Q t X : Power transmitted per user by the access point in Cell XQ r X : Wanted signal power received by a mobile station in Cell X.4.5.4.1 Case-1 Crossed Slots UL EbNo for CELL AIn this case, we are calculating the EbNo seen at the access point in Cell A when the interferer is theC⎛ E ⎞bdownlink from Cell B. We denote this ⎜ ⎟Nwhere the ‘C’ stands for crossed-slot and the ‘A’ indicates⎝ 0 ⎠ Athat we are examining the case for Cell A. We can write:CA⎛ E ⎞ P Wbr⎜ ⎟A B UN= ⋅( 4-4 )⎝ 0 ⎠ IU+ IDN RAAIntra-cell interference (I A U ) comes from other mobiles affiliated to the same access point, sharing the⎛ m ⎞Asame time slot. If there are m A users sharing the N C crossed slots then there are ⎜ ⎟−1intra-cell⎝ NC ⎠interferers. If we assume perfect power control such that the signals from all users are received with thesame power (P A r ) then:A⎛ m ⎞A AIU= ⎜ ⎟−1 PrN( 4-5 )⎝ C ⎠Inter-cell interference (I B D ) comes from the access point in the adjacent cell. The distance between theaccess points is 2D and the path loss can be written k(2D) -v where k and v are constants describing thepath loss characteristics of the channel. For the purposes of this model we assume v = 4, the value of k isunimportant for this analysis. We denote the power transmitted per user as Q B t and we can calculate the⎛ m ⎞Bnumber of users in Cell B per down link crossed slot as ⎜ ⎟, thus:⎝ NC ⎠B−vmBBI = k( 2 D) Q( 4-6 )DtNCWe further define P t A as the power transmitted by a mobile at distance r A from the access point. r A is theradius within which all mobiles affiliated to Cell A are positioned. We assume perfect power control, soall mobiles within the r A radius are received at the same power:Page 72 (121)

WINNER D2.5 v1.0PAr= kr P( 4-7 )−vAA tr AWe also define δA= which relates to the percentage of Cell A where mobiles are allocated uplinkDcrossed slots.Substituting into the original equation gives:⎛ E⎜⎝ NCA⎞bP N W⎟ =U0 ⎠ NRAA t A CδAt CA4{ P ( m − N ) + m Q }1B16Bt( 4-8 )which can be used in the modelling of uplink performance of crossed slots in Cell A.4.5.4.2 Case-2 Crossed Slots DL EbNo for CELL BIn this case, we are calculating the EbNo seen at a mobile station Cell B when the interferer is the uplinkC⎛ E ⎞bfrom Cell A. We denote this ⎜ ⎟Nwhere the ‘C’ stands for crossed-slot and the ‘B’ indicates that we⎝ 0 ⎠Bare examining the case for Cell B. We can write:CB⎛ E ⎞bQrW⎜ ⎟B A DN= ⋅( 4-9 )⎝ 0 ⎠ ID+ IUN RBBThe intra-cell interference (I B ⎛ m ⎞BD ) comes from power transmitted to the other ⎜ ⎟−1mobiles in Cell B⎝ NC⎠who share the crossed timeslot in question. We assume that all users have the same data rate requirementsthus the interfering signals will be received at the same power as the wanted signal (Q B r ). Thus:⎛B m ⎞BBID= ⎜ ⎟−1 QrN( 4-10 )⎝ C ⎠Inter-cell interference (I U A ) comes from mobiles within an r A radius from the centre of the cell. For thisanalysis we calculate the average interference from these mobiles. We define a general interfering mobilestation whose position is defined as polar coordinate (x, θ) using the centre of Cell A as the origin. Themobile is within the r A radius. We define the transmission power of this mobile station to be S. We knowfrom the previous section that if x = r A , S = P t A and that all mobiles are received at the access point withpower P r A . Therefore we can calculate S as a function of x:PAr= krP−vAA t= kx−vS⇒⎛S = ⎜⎝xrAv⎞⎟P⎠At( 4-11 )In the worst case, the mobile suffering the interference will be positioned at point K (see Figure 4-25) onthe intersection of a line drawn between the cell centres and a circle radius r B sharing its centre point with2 2l = 2D− r + x − 2 2D− r x cos .Cell B. The distance from K to the interfering mobile is ( ) ( ) θTherefore we can calculate the interference seen at point K from a mobile positioned at polar coordinates(x, θ) as:I−vA( x θ ) = kl S = k⎜⎟ Pv⎛ x ⎞,⎜ tlr ⎟( 4-12 )⎝ A ⎠We assume that the interference experienced by the worst case mobile at point K is the averageinterference level produced by all mobiles within the r A radius in Cell A. This averaging can beimplemented by time slot hopping, frequency hopping or the use of CDMA-type spreading codes. Thisaverage interference can be written:BBPage 73 (121)

WINNER D2.5 v1.0I =r A∫0∫2π0I( x,) q( x,θ )θ dθdx( 4-13 )where q(x, θ) is the pdf of mobile position. Since mobiles are assumed to be spread evenly over an areawithin an r A radius:xq( x,θ ) = ( 4-14 )2πr AThese equations can be solved to give the average inter-cell interference from a single mobile terminal:AkPtI = fB,C( δA, δB)( 4-15 )4Dwhere ( , δ )f B , C4 22( 2 −δ) + ( − )B6δA2 δB42 22δ ( 2 −δ) −δ22( 2 −δ) ⎡ ( ) ⎤⎪⎫B2 −δBln6 ⎢2 ⎥( ) ⎬δ 2 −δ−δ⎪ ⎭⎪⎧4− 4−δA4δA B= ⎨+( 4-16 )2⎪⎩ ( )AB AA ⎣ B A ⎦r Ar Band where δA= and δDB= are related to the percentages of Cell A and Cell B respectivelyDwhere mobiles are allocated crossed slots.⎛ m ⎞AThe number of users in Cell A per uplink crossed slot is ⎜ ⎟, thus:⎝ NC ⎠AA mAmAkPtIC= I = fB,C( δA,δB)( 4-17 )4N N DCCQ B r is the power received by the test mobile. Since we have assumed it is in the worst case positionmarked as K in Figure 4-25, the transmitted power per user at the access point in Cell B is related to thewanted signal power received at K as:B −vBQr= krBQtSubstituting into the original equation gives:⎛ E⎜⎝ NC⎞b⎟=0 ⎠ B B C t+W NC tB 4 Ad{( m − N ) Q δ m P f ( δ , δ )} NRBAQtBB,CAThis equation is used in the modelling of downlink performance of crossed slots in Cell B.BB( 4-18 )4.5.4.3 Case-3 Downlink Only Slot for CELL AFor this case, we calculate the EbNo seen at a worst case victim mobile terminal in Cell A when thed⎛ E ⎞binterferer is the downlink from Cell B. We denote this ⎜ ⎟Nwhere the ‘d’ stands for downlink slot and⎝ 0 ⎠ Athe ‘A’ indicates that we are examining the case for Cell A. We can write:dA⎛ E ⎞b QrW⎜ ⎟A B DN= ⋅( 4-19 )⎝ 0 ⎠ ID+ IDN RAAIntra-cell interference (I A D ) comes from the power transmitted by the access point in the same timeslot as⎛ M ⎞Athe wanted signal. If there are M A users sharing the N d down link slots then there are ⎜ ⎟−1other⎝ Nd ⎠users sharing the same time slot. We assume that all signals are received at the mobile terminal with thesame power (Q A r ) then the intra-cell interference can be written as:⎛A M ⎞AAI = ⎜ ⎟ QD−1 rN( 4-20 )⎝ d ⎠Inter-cell interference (I D B ) comes from power transmitted by the access point in Cell B in the same timeslot as the wanted signal. In Cell B there are (M B – m B ) users sharing the N d down link slots, thus thepower transmitted by the interfering access point in the slot in question is:Page 74 (121)

WINNER D2.5 v1.0⎛ MB− m⎜⎝ NdB⎞⎟Q⎠Bt( 4-21 )where Q t B is the power transmitted per user in Cell B.In the worst case the victim mobile terminal is positioned on the border between Cells A and B. Thereforethe interference power received by the mobile terminal from the access point in Cell B is:⎛B MB− m ⎞B B −vI = ⎜ ⎟ Q kDDtN( 4-22 )⎝ d ⎠Similarly, the wanted signal power received at the mobile terminal positioned at the border between CellsA and B is given as:A −vAQ = kD Q( 4-23 )rtWe also make the assumption that the power transmitted by a access point to a user is proportional to thedown link data rate, thus:A AQtRdB =B( 4-24 )Q RtdSubstituting into the original equation gives:d⎛ E ⎞b⎜ ⎟N⎝ 0 ⎠A=dd( M − N ) NR + ( M − m ) NRAdW NAdBBB( 4-25 )4.5.4.4 Case-4 Downlink Only Slot for CELL BFor this case, we calculate the EbNo seen at a worst case victim mobile terminal in Cell B when thed⎛ Eb⎞interferer is the downlink from Cell A. We denote this ⎜ ⎟Nwhere the ‘d’ stands for downlink slot and⎝ 0 ⎠ Bthe ‘B’ indicates that we are examining the case for Cell B. We can write:dB⎛ Eb⎞ QrW⎜ ⎟B A DN= ⋅( 4-26 )⎝ 0 ⎠ ID+ IDN RBBNote that there are similarities with the analysis in Section 4.5.4.3.Intra-cell interference (I B D ) comes from the power transmitted by the access point in the same timeslot asthe wanted signal. If there are (M B – m B ) users sharing the N d down link slots in Cell B then there are⎛ M − m ⎞B B⎜⎟−1other users sharing the same time slot. We assume that all signals are received at the⎝ Nd ⎠mobile terminal with the same power (Q B r ) then the intra-cell interference can be written as:B⎛ MB− m ⎞BBID= ⎜⎟−1 QrN( 4-27 )⎝ d ⎠Inter-cell interference (I A D ) comes from power transmitted by the access point in Cell A in the same timeslot as the wanted signal. In Cell A there are M A users sharing the N d down link slots, thus the power⎛ M ⎞A Atransmitted by the interfering access point in the slot in question is ⎜ ⎟QtNwhere Q A t is the power⎝ d ⎠transmitted per user in Cell A.In the worst case the victim mobile terminal is positioned on the border between Cells A and B. Thereforethe interference power received by the mobile terminal from the access point in Cell A is:Page 75 (121)

WINNER D2.5 v1.0I⎛ M⎜⎝⎞⎟⎠A A A −vD=⎜QtkDN ⎟( 4-28 )dSimilarly, the wanted signal power received at the mobile terminal positioned at the border between CellsA and B is given as:B −vBQ = kD Q( 4-29 )rtWe also make the assumption that the power transmitted by a access point to a user is proportional to thedown link data rate, thus:A AQtRdB =B( 4-30 )Q RtdSubstituting into the original equation gives:d⎛ E ⎞b⎜ ⎟N⎝ 0 ⎠B=dd( M − m − N ) NR + M NRBBWNddBAA( 4-31 )4.5.4.5 Case-5 Uplink Only Slot for CELL AIn this section we calculate the EbNo seen at the Cell A access point when interference is coming fromu⎛ E ⎞bthe uplink in Cell B. We denote this ⎜ ⎟Nwhere the ‘u’ stands for uplink slot and the ‘A’ indicates that⎝ 0 ⎠ Awe are examining the case for Cell A. We can write:uA⎛ E ⎞bPrW⎜ ⎟A B uN= ⋅( 4-32 )⎝ 0 ⎠ IU+ IUN RAAIntra-cell interference (I A U ) comes from the power transmitted by mobile terminals sharing the same⎛ M ⎞A− mAtimeslot as the wanted mobile, and also affiliated to Cell A. There are ⎜⎟−1such interfering⎝ Nu⎠mobiles each transmitting at a power such that the power received at the access point is P A r . Therefore thetotal intra-cell interference is:A⎛ MA− m ⎞A AIU= ⎜⎟−1 PrN( 4-33 )⎝ u ⎠Inter-cell interference (I B U ) comes from mobiles in Cell B using the time slot of interest. There areassumed to beM Bof these interfering mobiles, which can be positioned anywhere within Cell B. WeNudefine a general interfering mobile terminal whose position is defined as polar coordinate (x, θ) using thecentre of Cell B as the origin. We define the transmission power of this mobile terminal to be S, thereforeif we assume perfect power control, the power received from the interfering mobile station at its ownaffiliated access point is:vB −vx BPr= kx S ⇒ S = Pr( 4-34 )kThe distance from the interfering mobile to the access point at the centre of Cell A is2 2l = 4D+ x − 4D x cosθ . Therefore we can calculate the interference seen at the centre of Cell A dueto an interfering mobile in Cell B at point (x, θ) as:4 B−vx PrI( x,θ ) = k l S =( 4-35 )2 24D+ x − 4xDcosθ( ) 2We assume that the interference experienced is the average level produced by all mobiles with Cell B.This averaging could be implemented by time slot hopping, frequency hopping or the use of CDMA-typespreading codes. The average interference can be written:Page 76 (121)

WINNER D2.5 v1.0∫0∫2π( x,) q( x,θ )I = D I θ dθdx( 4-36 )0where q(x, θ) is the pdf of interfering mobile position. Since mobiles are assumed to be spread evenlyover the whole of Cell B:xq( x,θ ) = ( 4-37 )2π DThese equations can be solved to give the average inter-cell interference from a single mobile terminal:= 16ln4 −41( 4-38 )B( ( ) )I 3 9 P rThe total inter-cell interference can therefore be written:BB MBMBPrI = I = ( 16ln( 3)9)4 −41( 4-39 )uN NuuWe make the assumption that the received user power at the access point is proportional to the uplink datarate, thus:A uPrRAB =u( 4-40 )P RrBSubstituting into the original equation gives:u⎛ E ⎞bW Nu⎜ ⎟N=⎝ 0 ⎠A A u AlnAuu( M − m − N ) NR + ( 16 ( 3)9 ) 4 −41 M NRBB( 4-41 )This equation is used to model uplink to uplink interference performance for Cell A4.5.4.6 Case-6 Uplink Only Slot for CELL BIn this section we calculate the EbNo seen at the Cell B access point when interference is being generatedu⎛ Eb⎞by the uplink of Cell A. We denote this ⎜ ⎟Nwhere the ‘u’ stands for uplink slot and the ‘B’ indicates⎝ 0 ⎠ Bthat we are examining the case for Cell B. We can write:uB⎛ E ⎞ P Wbr⎜ ⎟B A uN= ⋅( 4-42 )⎝ 0 ⎠ IU+ IUN RBBNote that the analysis for this case is similar to that carried out in Section 4.5.4.5.Intra-cell interference (I B U ) comes from the power transmitted by mobile terminals sharing the same⎛ M ⎞Btimeslot as the wanted mobile, and also affiliated to Cell B. There are ⎜ ⎟−1such interfering mobiles⎝ Nu ⎠each transmitting at a power such that the power received at the access point is P B r . Therefore the totalintra-cell interference is:B⎛ M ⎞B BIU= ⎜ ⎟−1 PrN( 4-43 )⎝ u ⎠Inter-cell interference (I A U ) comes from mobiles in Cell A using the time slot of interest. There areMA− mAassumed to be of these interfering mobiles, which are positioned within Cell A greater than r ANufrom the centre. We define a general interfering mobile terminal whose position is defined as polarcoordinate (x, θ) using the centre of Cell A as the origin. We define the transmission power of this mobileterminal to be S, therefore if we assume perfect power control, the power received from the interferingmobile terminal at its own affiliated access point is:Page 77 (121)

WINNER D2.5 v1.0A −vPr= kx S ⇒ S =vxkPAr( 4-44 )The distance from the interfering mobile to the access point at the centre of Cell B isl =2 24D+ x − 4D x cosθ . Therefore we can calculate the interference seen at the centre of Cell B dueto an interfering mobile in Cell A at point (x, θ) as:−vI( x,θ ) = k l S =4 Ax Pr( 4-45 )2 24D+ x − 4xDcosθ( ) 2We assume that the interference experienced is the average level produced by all mobiles within Cell A.This averaging could be implemented by time slot hopping, frequency hopping or the use of CDMA-typespreading codes. The average interference can be written:I=∫∫Dr A2π0I( x θ ) q( x,θ ), dθdx( 4-46 )where q(x, θ) is the pdf of interferer mobile position. Since mobiles are assumed to be spread evenly overthe area bounded by the radius r A and the edge of the cell radius D:xq( x,θ ) = ( 4-47 )π2 2D −( )r AThese equations can be solved to give the average inter-cell interference from a single mobile terminal:AI = P rf δ( 4-48 )B,u( )Ar AWhere δA= is related to the percentage of Cell A where mobiles are allocated crossed slots, and:Df B , u22( 4 −δ)⎛ − ⎞( ) ⎥ ⎥ ⎤A− 64 185 4 δA− + 16ln⎜⎟2 24 − δ 9 ⎝ 3A⎠⎦1 ⎡2 80( δA) = ⎢δ+2 A( 4-49 )( 1−δ)A ⎢⎣The total inter-cell interference can therefore be written:( )( ) ( )A MA− mAA MA− mAIu= I = PrfB uδ( 4-50 ), ANNuuWe make the assumption that the received user power at the access point is proportional to the uplink datarate, thus:A uPrRAB =u( 4-51 )P RrBSubstituting into the original equation gives:u⎛ E ⎞b⎜ ⎟N⎝ 0 ⎠B=uu( M − N ) NR + f ( δ )( M − m ) NRBuBW NB,uuAAAA( 4-52 )This equation is used to model uplink to uplink interference performance for Cell B.4.5.4.7 Summary of TDD Interference AnalysisTable 4-6 summarises the equations to be used in the analysis of TDD interference.Page 78 (121)

WINNER D2.5 v1.0Table 4-6: Summary of EbNo Equations for TDD Interference ScenariosDescriptionDownlink Interfering with Uplink in Crossedbt CSlots⎜U AN ⎟4NR { P ( m − N ) + m Q }1B16Uplink Interfering with Downlink in CrossedEquationCA⎛ E ⎞P N W⎜ ⎟ =⎝ 0 ⎠ AA t A CδA B tCB⎛ E ⎞W N Q⎜ ⎟ =⎝ 0 ⎠BB C t+B A t B,C A Bd⎛ E ⎞bW Nd⎜ ⎟N=⎝ 0 ⎠ MA A− NdNRA+ MB− mBNRBd⎛ E ⎞bWNd⎜ ⎟N=⎝ 0 ⎠ MB B− mB− NdNRB+ MANRAu⎛ E ⎞bW Nu⎜ ⎟ =⎝ 0 ⎠ AA A u Alnu⎛ E ⎞bW Nu⎜ ⎟N=⎝ 0 ⎠ MB− NuNRB+ fB,uδAMA− mANRbC tSlots⎜BAdN ⎟4{( m − N ) Q δ m P f ( δ , δ )} NRDownlink Interfering with Downlink dd( ) ( )Downlink Interfering with Downlink dd( )Uplink Interfering with Uplink ⎜uuN ⎟ ( M − m − N ) NR + ( 16 ( 3)9 ) 4 −41 M NRUplink Interfering with Uplink uu( ) ( )( )4.5.5 TDMA on Uplink and DownlinkTo investigate the effects of UL/DL asymmetry the equations derived in section 4.5.4 are applied to asystem comprising TDMA in both uplink and down link with three allocation strategies being contrasted:Case A: Random allocation of mobiles to timeslotsCase B: Mobiles in Cell A are allocated randomly. In Cell B, mobiles closest to the access pointare allocated to crossed slots.Case C: In both cells, mobiles closest to the access point are allocated to crossed slots.The model was set up with 200 (= M A = M B ) users in each of Cell A and Cell B, a frame was defined ashaving an arbitrary large number of slots (N), and system bandwidth was defined as 20 MHz. User datarates (R u A , R d A , R u B , R d B ) were varied between 1 and 31 kb/s with R u A + R dA = R u B + R d B = 32 kb/s.Other required values can be calculated as shown below:NNN =ud; N =d; N = N − N − Nucd uRB1+RAu1+dRRcδA=;cBNN + Nm AMuδ =BcANcN + N2= δ ; mA AB= δ2MB BdFor each run of the simulation, UL and DL transmit powers (Q t B and P t A ) were chosen such thatcc⎛ E ⎞ ⎛bE ⎞b⎜ ⎟ ⎜ ⎟N=N. Note that this is an arbitrary choice, in reality the EbNo targets will be service⎝ 0 ⎠ A ⎝ 0 ⎠ Bdependent and may be different for UL and DL. It is however important to note that the two are linked byequations (4-8) and (4-18).BBABB4.5.5.1 Case A: Random AllocationTo model random allocation, when calculating for crossed slots δAwas set equal to 1 and δBwas setclose to 1. This allows crossed slot mobiles to be allocated anywhere within their respective cells. Whencalculating for uncrossed slots both δ Aand δ Bwere set to 0. This allowed uncrossed mobiles to beallocated anywhere within their respective cells.When a mobile is allocated to a crossed slot with no account taken of its position within the cell,problems start to occur. Particularly, UL to DL and DL to UL interference grows very large when twomobile stations are close together at a cell boundary: DL power is increased which increases interferencePage 79 (121)

WINNER D2.5 v1.0into the UL. This in turn causes uplink power to be increased thus forcing the DL power to increase tocompensate. The obvious solution is to enforce a separation between mobiles sharing a crossed slot.4.5.5.2 Case B: Specific Allocation for DL Crossed SlotsA first solution is to require DL crossed slots to be allocated only to those mobiles closest to the centre ofthe cell [JEO-00]. This has two beneficial effects:• DL transmit power in the crossed slots is reduced thereby reducing DL to UL interference• Physical separation of DL and UL mobiles sharing crossed slots reduces UL to DL interferenceTo model this case, when calculating for crossed slots, δAwas set equal to 1. This allows mobiles in CellA allocated to uplink crossed slots to be positioned anywhere in the cell. Mobiles in Cell B allocated todownlink crossed slots are restricted to the area around the centre of the cell.⎛ E ⎞Figure 4-27 shows how ⎜ b⎟varies as asymmetry within Cell B changes. The switching point of Cell A⎝ N 0 ⎠is set such that the ratio of downlink to uplink data rates is 1:1. The performance of all other interferencecases is unaffected.3025EbNo2015101 2 3 4 5 6 7Ratio of Downlink to Uplink Data Rate in Cell BFigure 4-27: The Effect of Traffic Asymmetry on Crossed-Slot EbNo for Case B4.5.5.3 Case C: Specific Allocation for UL & DL Crossed SlotsAn extended version of Case B (section 4.5.2) was applied to crossed slot allocation such that both uplinkand downlink crossed slots were allocated to those mobiles closest to their respective access point. Thishad the effect of further increasing the distance between mobiles sharing a crossed slot and thusimproving the performance compared with Case B. The improvement can see seen in Figure 4-28.Page 80 (121)

WINNER D2.5 v1.0454035EbNo3025Case BCase C2015101 2 3 4 5 6 7Ratio of Downlink to Uplink Data Rate in Cell BFigure 4-28: Comparison Between Cases B and C of EbNo for Crossed Slots.Assumes Cell A Uses a 1:1 DL:UL RatioHowever, there is a loss in interference performance for Cell B. Figure 4-29 shows this degradationcompared with Case A and Case B for a range of switching point offsets.191817EbNo16Case A / Case BCase C1514131 2 3 4 5 6 7Ratio of Downlink to Uplink Data Rate in Cell BFigure 4-29: Comparison Between Cases A, B and C of EbNo for Uplink Uncrossed Slots in Cell B.Assumes Cell A Uses 1:1 Downlink to Uplink RatioThe reason for this degradation is that mobiles in Cell A that are allocated to uncrossed uplink time slotsare those which are outside the r A radius, and therefore closer to the edge of the cell. This has a dualnegative effect. Firstly they transmit with a higher transmit power to maintain communications with theiraffiliated access point. Secondly, distance from the access point to the more significant interferers is nowreduced. Notice however that for small differences between the switching points of the cells we see onlysmall degradations in uplink to uplink performance and a larger improvement in crossed slotperformance. It may be possible to tune the allocation strategy to sacrifice some crossed slot performancefor uncrossed slot performance. This is for further study.Page 81 (121)

WINNER D2.5 v1.0This method of allocation has a simpler implementation than for Case B since no knowledge is requiredof the switching point in the adjacent cell. Mobiles closer to the access point are allocated to slots closerto the switching point. If adjacent cells use the same strategy, and only one switching point is defined foreach frame, then mobiles allocated to crossed slots will be those closest to the access point.One disadvantage of this strategy is that mobiles close to the access point will have very little time toswitch from UL transmission to DL reception since both UL and DL timeslots will be allocated close tothe switching point. Mobiles at the outer edges of the cell will have the same problem but in reverse withshort switching time from DL to UL. In practice some compromise may be required such as introducing aminimum distance between UL and DL slots allocated to the same mobile.4.5.6 Time Slot Hopping for Crossed Slot Interference AvoidanceIn any cellular system, maximum efficiency is made of the resources when interference is shared evenlyamong the users. In narrow band systems, such as GSM, studies have shown frequency hopping to givesignificant capacity gain.In the analysis above the interference from UL MTs received by the test DL MT is assumed to be theaverage interference seen from all crossed slot mobiles in the adjacent cell. For a TDMA frame structureit should be possible to achieve a similar effect by employing timeslot hopping. By pseudo-randomlyhopping users over the time slots, the interference seen by each user in an adjacent cell will, over time, bean average of possible interferers from the adjacent cell.However, for the slot allocation strategy described in Section 4.5.2 channels allocated to crossed slotsshould only be allowed to hop to other crossed slots and channels allocated to uncrossed slots should onlybe allowed to hop to other uncrossed slots.The disadvantage of this scheme is that it is necessary for the cell to know which slots are crossed, andtherefore requires knowledge of the switching points used by neighbouring cells.An alternative arrangement is to allow channels to hop over a restricted distance within the frame. Usingthis method, mobiles close to the access point will hop over a group of time slots close to the switchingpoint and mobiles closer to the cell edge will hop over a group of time slots which are unlikely to becrossed. A simple algorithm to achieve this would be:SLOT(FRAME_NO) = (SLOT_ZERO + ((CELL_ID xor FRAME_NO) (mod HOP_DIST))) (mod N_SLOTS)SLOT(F): slot used for frame number FSLOT_ZERO: SLOT(0) for the channelCELL_ID: identification number for the cellFRAME_NO: current frame numberHOP_DIST: allowed hopping rangeN_SLOTS: total number of slotsxor: Exclusive-OR operatormod: modulus operatorThe disadvantage with this scheme is that more mobiles would use crossed slots relating to a larger areawithin the centre of the cell; this in turn would lead to higher transmit powers on the downlink and closerseparation of interfering mobile stations. Therefore, there is a trade-off between hopping over enoughslots to achieve sufficient crossed slot performance and ensuring the separation of potentially interferingmobiles.4.5.7 Conclusions on Slot Allocation StrategyThis section has presented a simple slot allocation strategy designed to minimise the effects of crossedslot allocation with closed form investigation of the performance of the technique.This simplified approach has shown that careful allocation of mobiles to time slots based on the locationof the mobile within the cell gives significant gains compared with a more random allocation strategy.Two variants of the allocation scheme were investigated: first, allocation of DL crossed slots was limitedto those mobiles closest to the access point (Case B); for the second scheme, allocation of all crossed slotswas limited to those mobiles closest to their respective access point (Case C). Case C showed betterperformance than Case B for crossed slots, but at the expense of UL to UL interference in Cell B.Page 82 (121)

WINNER D2.5 v1.0Performance degradation increases as the number of crossed slots in the system increases, this is due tothe increased number of mobiles using crossed slots and thus the reduced separation between mobiles inthe UL to DL interference case and the increased DL transmission power in the DL to UL interferencecase.Case C can be more easily implemented since no knowledge is required of the switching point in theneighbouring cell, and multiple adjacent cells are accommodated.4.5.7.1 Further WorkIn order to make the analysis tractable and due to project constraints a number of simplifying assumptionshave been made. This section outlines further investigations that may be considered in other Winner workpackages.The analysis presented here considers only two cells. Future simulations should include a larger numberof cells and therefore interference cases. A network architecture including sectored cells should also bestudied.A system simulation using a more accurate channel model, especially for AP to AP interference, shouldbe investigated to show that DLUL interference is the dominant interference problem for scenarios ofinterest.The analysis presented in this section has considered two synchronised, non-overlapping, yetuncoordinated cells. A useful addition to the work would be to investigate whether a similar interferenceavoidance technique could be employed for the cells of two different operators using TDD. There are anumber of issues to be considered including ULUL and DLDL interference constraints when the twoAPs are not co-located.The concept may need to be developed depending on the multiple access and modulation schemesadopted by the Winner project.Page 83 (121)

WINNER D2.5 v1.05. Terminal complexity considerations5.1 IntroductionThe purpose of this chapter is to analyse the complexity of the different duplex schemes defined in Ch.2.The chapter is divided into two main sections. The first part, section 5.2, concentrates on the complexityof the terminal. In the second part, section 5.3, initial RF requirements are derived for AP and MT; herethe main emphasis lies on a TDD-based system, but also the requirements for other systems are brieflyaddressed. Some remarks on the consequences for selected duplex schemes can be found in Sec. 5.3.5.For convenience, a brief RF dictionary is provided in Sec 5.4.5.2 Terminal Complexity5.2.1 Selection of the transceiver architecture for this studyWhen receiving wideband signals, like in the case of WINNER air-interface, the potentially high powerconsumption of the analog-to-digital converters (ADC) rules out all digital intermediate frequency (IF)solutions; the conversion to the digital domain has to occur at the baseband. For example superheterodyne,wideband IF, and the direct conversion (DiCo) architectures can be used [RAZ-98, PAR-02].Direct conversion receiver (RX) and transmitter (TX) were selected for the transceiver architecture understudy. Direct conversion is commonly used in today’s modern terminals because of the low cost, smallsize, and low power consumption. In the context of multiple-input, multiple-output (MIMO) transceiversthese factors become even more critical due to there being several transmitters and receivers in the radio.Short introduction to the non-idealities in direct conversion receiverThis section introduces the most critical non-idealities of the DiCo RX, characteristics of this architecture.Typical receiver non-idealities like third-order nonlinearity and phase noise are not discussed here. Mainfocus is in the dynamic direct current (DC)-offset.Static DC offsetThe main problem with the DiCo RX is the handling of the DC at the baseband. Because the requiredbaseband gain is typically rather large, the amplified DC-offset may easily saturate the receiver. Main partof the static DC-offset is generated by the DC-offsets of the circuits, but also local oscillator (LO) leakageand LO self-mixing contribute. It is rather straightforward to remove the static DC-offset, for examplewith a high-pass filter. To reduce the LO leakage, the local oscillator is typically designed to operate atthe double frequency of the RF, and the LO signals are generated with a divide-by-two-circuit.Dynamic DC-offsetThe main source of the dynamic DC-offset is the second-order nonlinearity of the receiver. A weaknonlinearity can be modeled by presenting the transfer function of the circuit as a Taylor series: V out =αV in +βV in 2 +χV in 3 +…where α, β, and χ are constants. If a sinusoidal signal is applied to this function, thesecond order term βV in2will generate a DC term and a sinusoidal at the double frequency of the originalsignal. However, an input signal with a varying envelope will generate a varying signal at DC. This iscalled dynamic DC offset.The effect of second-order nonlinearity is typically of concern when receiving a weak signal while anamplitude-modulated, high-power interference signal is entering the receiver at some frequency offsetfrom the desired channel. The arising second-order intermodulation product (IMD2) now disturbs thereception. The dynamic DC-offset is trickier to remove than the static DC-offset. This is because thedistortion signal occupies the same frequency band than the wanted signal. Consequently, the distortionsignal cannot be removed by filtering.The main source of second-order nonlinearity in DiCo receivers is typically the down-conversion mixers.Different methods have been proposed to improve the second-order nonlinearity of the mixers. Inaddition, all the phenomena generating static DC-offset can also cause dynamic DC-offset when someoperating condition, such as gain or LO leakage, is changed. For example, dynamic DC offset occursPage 84 (121)

WINNER D2.5 v1.0when LO leakage to antenna is present and the gain of the low-noise amplifier (LNA) is changed as a partof gain control. The gain change then modulates the leakage, which is self-mixed to dynamic DC-offset atthe baseband. This causes a ramp signal, which adds on top of the wanted signal.I/Q-imbalanceThe amplitude and phase balance of the receiver in-phase and quadrature-phase signal branches starts tobe critical when high-order modulations are considered. In OFDM systems, I/Q imbalance generatesinter-carrier interference. Previously, the I/Q-imbalance has not been much of an issue in cellularreceivers because of the low-order modulation schemes involved. In contrast, in the wireless LAN worldthe IQ–imbalance presents a problem, since 64-QAM has been specified as maximum modulation. If themodulation order is further increased, the direct conversion architecture becomes unfeasible and a digitalIF sampling architecture should be used instead. In digital IF-sampling architecture the problem is therequired high dynamic range of the analog-to-digital converters (ADC), resulting from the high SNRrequirement of the high order modulation. Combined with very high sampling rate (related to the 100MHz bandwidth), the power consumption will increase too much for MT application. Hence, high-ordermodulation combined with cellular-type, wideband operation in an interference-rich radio environmentposes a severe problem for MT implementation. For AP this is still feasible.The receiver tolerance to I/Q imbalance can also be enhanced by digital means, at the cost of increasedcomplexity of the digital baseband.Short introduction to the non-idealities in direct conversion transmitterDirect conversion TX does exactly the opposite than DiCo receiver. However, since the only signalpresent is the in-band signal, the relative importance of the non-idealities is different than in receiver. Thedominant non-ideality is the nonlinearity of the power amplifier (PA), affecting signal quality andadjacent channel power leakage, but this is a common problem to almost all TX architectures. Other nonidealitiesof importance are I/Q-imbalance, non-linearity of the baseband and mixers, noise, phase noise,and LO pulling. Digital-to-analog converters (DAC) have finite number of bits, but this is not as critical aproblem as the number of bits in receiver ADC’s, since the power consumption of the DAC’s is lower.TX non-idealities influence mainly the quality of the signal, adjacent channel power leakage, and thetransmitted noise floor. The requirements for the adjacent-channel power leakage and transmitter noisefloor will be discussed below.5.2.2 Brief introduction to the functional blocks in an example transceiverFigure 5-1 shows possible transceiver architecture to be used in TDD operation; variants for FDD,(T+F)DD, and CDD are discussed in following sections. The upper part forms the transmitter, the lowerpart the receiver. The functional blocks of the receiver RF parts are:1. Bandpass RF filter. In order to increase the interference tolerance from and to other systems, thispass band filter is needed. If operated in FDD, this filter is replaced with duplexer, see Figure5-2.2. RX/TX switch. The main functionality of this block is to isolate the impedances of the receiverand transmitter from each other and to connect them to the antenna (21). This makes theimplementation more straightforward. Attenuation of the filter (1) and switch has largestcontribution to the receiver noise figure. Also if the attenuation is large, power amplifier (PA)has to drive more output power in order to achieve same output power at the antenna.3. Low noise amplifier (LNA) is the first active block in the receiver chain. This amplifier has thelargest contribution to the receiver noise figure (NF=SNR out/SNR in) from the active blocks. This isevident since all the following blocks now amplify the noise generated by the LNA.4. IQ-demodulator. Ideally these down-conversion mixers just multiply the incoming signal withthe local oscillator signal generated by the divider (15) and the synthesizer (16). Since thefrequency of the LO is now the same as the center frequency of the incoming signal, the signal isconverted to the baseband, centered around zero frequency. Since upper and lower sidebands aredown-converted atop each other, two phase-quadrature branches, I-branch and Q-branch, areneeded; otherwise the side bands cannot be resolved. These mixers are the main source of thesecond order non-linearity. Moreover, any phase or amplitude difference between the branchesresults in effective leakage between the sidebands.5. Programmable gain stage of the receiver. The most of the baseband gain of the receiver islocated here. Automatic gain control (AGC) adjusts the gain such that the level of the inputsignal is suited to the dynamic range of the analog-to-digital converters.6. Channel selection filter. The main task of this analog filter is to suppress any interfering signalsin the adjacent channels; it also removes the second harmonic which results from mixing. ThePage 85 (121)

WINNER D2.5 v1.0requirements for the analog filter follow from blocker specifications (how large signals can be atthe adjacent channels) and the bit count and sampling rate of the analog-to-digital converters (8).The more bits are available, the more selectivity can be realised with digital filter (11) and theless selectivity needs to achieved by the analog filter. The reason for this is that ADC’s limit thestrength of the blocking signals: if the blocker is much higher than the wanted signal, thequantization noise of the ADC will destroy the wanted signal. Channel selection filter also servesas an anti-alias filter for the ADC. Implementation of the filter becomes problematic if thebandwidth is too large.7. Buffering stage for the ADC; needed if a high-speed ADC is to be used.8. Analog-to-digital converters are one of the most problematic blocks for wideband signalreception. To allow for digital filtering, the minimum sampling frequency is twice the Nyqvistsampling rate. For the RF signal bandwidth of 100 MHz (BB bandwidth 50 MHz), the Nyqvistrate is 100 MHz and, consequently, the minimum practical sampling rate is 200 MHz. At themoment, the power consumption of a high-bit, say, pipeline ADC at sampling rate 200 MHzappears to be unfeasibly high for MT application. Consequently, only 6-7 bits can be afforded.This further implies steep requirements for the analog channel selection filter.9. DC offset removal, required if DC sensitive algorithms are to be used in PHY layer.10. Signal level measurement. This received signal strength indicator is used to measure the signallevel for the AGC. This is not the same RSSI, which is reported for example for the powercontrol.11. Digital filter, used to finalise the channel filtering.The transmitter components are as follows:12. Power amplifier (PA), the main source of the transmitter non-linearity. Non-linearity generatesin band errors/distortion and adjacent channel power (ACP) leakage. With signals which havehigh peak-to-average-power ratio (PAPR) like OFDM signal, average output power of the PAhas to be backed off several dB because of the ACP reducing the power efficiency. Powercontrol can be done changing the supply voltage of the PA by DC-DC converter. This savespower.13. Preamplifier, amplifies the power from the modulator (14) to suitable power level14. I/Q modulator. This block up-converts the I and Q signals so the side bands are suppressed byimage rejection.15. Divide-by-two circuit with 90 degrees phase shift. Synthesizer (16) operates typically at twotimes the signal frequency to gain isolation between the output power and synthesizer to reducelocal oscillator pulling effect.16. Synthesizer generates the phase locked LO frequency. Synthesizer is phase locked to the crystaloscillator.17. Analog low-pass filter, filters out the quantization noise and image signals of the digital-toanalogconverter (DAC,18)18. Digital-to-analog converters (DAC) take digital bits and convert them to the analogrepresentation. DAC can be designed to operate at high speed easier than ADC.19. Digital low-pass filter, needed if the spectral shape of the signal has high side slopes, eitherbecause of the peak-to-average reduction or/and because of the basic signal waveform it-self.For example in OFDM signal the IFFT generates signal, which has to be filtered in order toachieve sufficiently low power leakage to adjacent channels, see Sec. 5.3.2.4.20. Peak-to-average signal reduction. Optional, can be for example clipping. In OFDM themaximum peaks are large but occur very seldom.21. AntennaImpulse response of the Tx-Rx chain includes contributions from all the filters in the link (19, 17, 6, 9 and11). This and the delay spread in the channel have to be taken into account when the length of the guardinterval is selected.Page 86 (121)

WINNER D2.5 v1.02112312134LOq14LOqπ/215LOi141716Synt h.175 6 718DAC18DACADC8AGC logic19199PARREDUCTION201110RSSIQIQLOi45 6 7ADC8911IFigure 5-1: Possible block diagram of a transceiver operating in TDD5.2.3 Complexity of TDD5.2.3.1 Possible block level diagram of a transceiverBlock level diagram in Figure 5-1 can be used to design a MT transceiver operating in TDD mode.5.2.3.2 Critical non -idealities related to the TDD operationIn TDD, the transceiver is not transmitting and receiving at the same time. Because of this, only onesynthesizer is needed. RX/TX switch is used to isolate the receiver input from the TX power. RF filtercharacteristics are now defined by the out-of-band spectrum emission requirements and from the isolationrequirements from the other systems. It is possible to make the insertion loss of such filter rather small.Insertion loss of a switch is typically less than 1 dB. Since there is no interaction between RX and TX,reuse of operational blocks, such as channel selection filters, is possible, meaning cost savings. Thisbecomes important when multi-antenna transceivers are considered.In TDD it is crucially important that the networks are synchronised. The problem is the small isolationbetween MS-MS and AP-AP. Synchronization means that MS(AP) transmission and MS(AP) receptiondo not occur at close proximity and at the same time in the networks in the same geographical area. Itwould be very difficult to implement a transceiver satisfying the RF requirements needed forunsynchronous TDD operation. Also, it has to be noted that radios would not be capable to handle theworst-case situations (e.g., co-located or merely nearby AP’s, or near-by MT’s operating on differentchannels) in such a network, meaning that the data should be retransmitted in case of collision. Initial RFrequirements, attached at the end of this document, give more insight to this matter. Interferencemanagement is also discussed in Ch. 4.5.2.3.3 Power consumption aspectsSynchronised TDD does not have additional impact on the power consumption. Issues that have impact tothe power consumption of the TDD case are similar to those of all the other duplex schemes: for examplethe number of antennas, used waveform and adjacent channel properties of the RX and TX. The shape ofthe RF filter does have impact on the insertion loss of the filter and thus to the power consumption, but ithas to be noted that out-of-system-band attenuation requirements are again common for all the duplexmethod.Page 87 (121)

WINNER D2.5 v1.05.2.4 Complexity of FDD5.2.4.1 Possible block level diagram of a transceiverA transceiver architecture suitable for FDD operation is illustrated in Figure 5-2. The main differences tothe architecture in Figure 5-1 are the appearances of the duplex filter (shown as two connected filters inplace of the RF filter (1)) and a potential extra RX filter, and the need for two separate synthesizers.π/2LOqLOiSynth.DACDACPARREDUCTIONQILOqADCQπ/2Synt h.AGC logicRSSILOiADCIFigure 5-2: Possible block diagram of a transceiver operating in FDD5.2.4.2 Critical non -idealities related to the FDD operationFDD operation has the biggest impact on the RF architecture. Firstly, in FDD the transmission andreception occur at same time at different frequencies. Consequently, both RX and TX need to have theirown synthesizers. Secondly, a high-quality duplex filter is needed. The TX-branch of the duplexerconstitutes a band filter for the downlink band, while the RX-branch of the duplexer serves as a bandfilter for the uplink. Most importantly, the duplexer has to provide sufficient TX-RX isolation.The problem is that the transmitted signal leaks to the input of the receiver, increasing the noise figure ofthe receiver and generating DC offset through the second-order non-linearity of the mixers. The capabilityof the receiver to receive weak signals under such conditions can be improved by three means. The firstpossibility is to add one external RX filter to reduce the TX leakage to a tolerable level, as shown in thefigure; this increases slightly the power consumption, noise figure, and cost. The second approach is tomake the receiver more linear from the second-order non-linearity point-of-view. The third approach is toincrease the duplex filter attenuation from the TX port to the RX port. This last option increases thepower consumption of the TX and RX because of the higher inband attenuation of the duplexer. This isalso very much dependent on the duplex frequency separation.The problem with the combination of the multi-carrier signal like OFDM and FDD is that the peak-toaverage-power-ratio(PAPR) is large, which translates to higher IMD2 product in the receiver. This wouldnot be a problem with constant envelope TX signals or even with moderate envelope variations. It ispossible to implement FDD, but at the expense of unnecessary increase in the complexity. For AP theseissues are easier to implement.5.2.4.3 Power consumption aspectsThis duplex method has potentially higher power consumption than others (excluding CCD) mainlybecause of the simultaneous RX and TX operations: the power consumption is increased because of twosynthesizers, higher insertion loss of the duplexers, and because of the TX leakage. Naturally, when TXand RX are on at the same time, the peak power consumption is much higher as compared to the TDDand such a FDD/TDD hybrid without simultaneous TX and RX. The power management has to be scaledso that enough power is available for both RX and TX. Also, the total average power consumption shouldbe kept at such a level that the surface temperature of the device does not increase too much. This is onlypossible if the duty cycle of the RX and TX are kept low. In addition, if the duty cycle of the RX and TXis less than 50 %, it is preferable to use TDD or FDD/TDD hybrid instead. In MIMO operation,continuous transmission and reception in FDD and with 100 MHz band is not reasonable scenario onlybecause of the high power consumption.Page 88 (121)

WINNER D2.5 v1.05.2.5 Complexity of (T+F)DD5.2.5.1 Possible block level diagram of a transceiverA transceiver architecture suitable for (T+F)DD operation is illustrated in Figure 5-3. The maindifferences to the architecture in Figure 5-1 is the appearance of the duplex filter in place of the RF filter(1). Also two separate RF filters and a switch can be used in place of the duplex filter.π/2LOqLOiSynt h.DACDACPARREDUCTIONQIADCQLOqAGC logicRSSILOiADCIFigure 5-3. Possible block diagram of a transceiver operating in (T+F)DD5.2.5.2 Critical non -idealities related to the (T+F)DD operation(T+F)DD has similar properties as TDD in the sense that transmission and reception alternate. However,transmission and reception occur at different frequency bands, which means that filtering can be used toimprove the isolation between UL and DL bands (reducing AP-AP and MT-MT interference). Comparedto FDD, the main differences lie in the less strict requirements for the duplex filter and receiver linearity,and in that only one synthesizer is needed. In (T+F)DD, the attenuation requirement from the TX port tothe RX port is easier to implement because RX and TX are not on at the same time. The critical designparameter in duplex filter design is the TX noise attenuation to the RX band (radiated noise). Attenuationrequirement has direct impact on the insertion loss of the filter and thus to the power consumption. Due tothe different reception and transmission frequencies, the synthesizer has to change LO frequency betweenRX and TX slots. It is important to take into account in the scheduling that the frequency settling time isfinite. If this is not taken into account, two synthesizers are needed.5.2.5.3 Power consumption aspectsPower consumption aspects are similar to TDD case.5.2.6 Complexity of CDDThis case is added here just to make clear why code division duplex (CDD) is not considered as a realcandidate for WINNER air interface duplex method.5.2.6.1 Possible block level diagram of a transceiverAs can be seen from the picture below, the transmitter is directly connected to receiver and transmissionoccurs simultaneous with reception. It is also possible to use separate antennas for RX and TX. Thisincreases the isolation between TX and RX with a couple of tenth of dB. Unfortunately, this is notsufficient to solve the problems of CDD.Page 89 (121)

Dynamic range of the receiverWINNER D2.5 v1.0π/2LOqLOiSynt h.DACDACPARREDUCTIONQIADCQLOqAGC logicRSSILOiADCIFigure 5-4: Possible block diagram of a transceiver operating in CDD5.2.6.2 Problems with CDDAs seen from Figure 5-4, the receiver is operating at the same frequency simultaneously with thetransmitter. The division of the signals is supposed to happen in the code domain. The main problem withthis approach is that huge dynamic range of the receiver would be required. On the upper side the limitingfactor is the compression of the receiver (analog parts and ADC) and from the lower side the quantizationnoise of the ADC. Dynamic range of the analog-to-digital converter is not infinite; it is roughly 6 dB / bit.In addition to these, the gain of the receiver has to be low in order to be able to get the high TX powerthrough from the ADC. This means that there has to be attenuation in the low noise amplifier (LNA),which means that the noise figure will be very high. To summarise, CDD is not a feasible candidate forWINNER radio duplex method.Power [dBm]TX signalCompressionTX noiseRX signalQuantization noiseRX noise=-174+NF dBm/HzFigure 5-5: Dynamic range problem of the CCDFreq [Hz]5.2.7 Duplex casesIn this chapter, the complexity analyses discussed above are related to the duplex cases defined in Ch. 2.5.5.2.7.1 Pure FDDThis case is full-duplex FDD and complexity of FDD applies for both MT and AP. The downsides ofFDD are not severe in AP since proper duplexer can be build and TX and RX can have separatesynthesizers with lower additional cost and complexity. Pure FDD increases the complexity of the MTunnecessarily.Page 90 (121)

WINNER D2.5 v1.05.2.7.2 Half-duplex FDDAP operates in FDD and MT operates in (T+F)DD. The downsides of FDD are not severe in AP sinceproper duplexer can be build and TX and RX can have separate synthesizers with lower additional costand complexity.5.2.7.3 Pure TDDThis is typical TDD case. Complexity of TDD applies here.5.2.7.4 DL oriented hybridThis case is a hybrid TDD/FDD case. MT has to operate in TDD at the lower frequency band and(T+F)DD with both upper and lower frequencies. Also FDD is possible but not preferable. If FDD is usedadditional components should be placed to block diagram in Figure 5-6 (extra phase-locked loop (PLL)and filters). AP operates in FDD and TDD. AP can have similar TRX block diagram except it needs twoPLL and the NB and WB band are switched. This approach needs only one transmitter in MT.NB DL+ULπ/2LOqLOiSynt h.DACDACPARREDUCTIONADCWB DLLOqAGC logicRSSILOiADCIFigure 5-6: MT used in DL oriented hybrid5.2.7.5 Dual band TDD hybridFigure 5-7 shows a MT transceiver operating with one variant of TDD. Since the channel bandwidth isvariable the baseband channel selection filters are tunable. Separate RF filters and switches are added forboth frequency bands. Also, power amplifiers and LNAs are separate. With this structure it is possible totransmit and receive at both frequency bands with different signal bandwidths.Band 1LOqπ/2LOiSynth.DACDACPARREDUCTIONQIBand 2LOqADCQAGC logicRSSILOiADCIFigure 5-7: Example of operating in dual band TDD hybrid at two different bands5.2.7.6 Dual band switched hybridThe problem with this approach is that it requires very short PLL frequency settling. Reasonableswitching time of a fractional-N PLL is around 40 us.Page 91 (121)

WINNER D2.5 v1.05.3 Initial RF requirementsIn this section, initial RF requirements are derived for AP’s and MT’s. The calculations have been carriedout mainly with synchronised TDD (TDMA/FDMA) and dual-band TDD in mind. Chosen requirementsfor other duplex schemes are also provided, see the discussion below; conclusions for selected duplexschemes are briefly commented in Ch. 5.3.5.An issue of crucial importance in TDD is whether the network is synchronous, i.e., whether the uplinkdownlinkswitching point occurs within a specified guard time for all frequency channels and alloperators in the network. The difference is that in a synchronous network there is only MT-APinterference, whereas in an unsynchronous network AP-AP and MT-MT interference dominate.Consequently, the RF requirements for an unsynchronous network are very stringent, part unfeasible forimplementation. Here, fairly comprehensive requirements are provided for a synchronous TDD network.For an unsynchronous network, those basic requirements which have interpretation for FDD-based duplexschemes are presented as footnotes.Most requirements for other duplex schemes can be derived from the requirements for synchronous andunsynchronous TDD. The interpretation of the requirements for FDD and half-duplex FDD are discussedin Ch. 5.3.5. The basic difference in the interpretation for TDD and FDD is that in FDD UL and DL occurat different frequency bands. Hence, in FDD a duplex filter can be used to alleviate implementing therequirements arising from AP-AP or MT-MT interference, whereas in TDD the requirements must be metwith circuit design techniques only. Hence, the very same RF requirement may be easy to implement forFDD, yet be difficult or practically impossible to implement for TDD.To estimate the RF requirements, various scenarios were constructed, where one or several MT’s and/orAP’s are simultaneously transmitting and hence appear as interference to each other. Analysis showsthat,despite there being many such combinations of AP’s and MT’s, only few scenarios are found todominate the RF requirements. Here, only the dominant cases are mentioned.The requirements obtained are based on many assumed parameters, such as the output powers. Equationsare provided so that the assumptions and the resulting performance requirements can be updated.5.3.1 AssumptionsThe system is assumed to support two different bandwidths: a wideband (WB) mode and a narrowband(NB) mode. The basic parameters for the modes are listed below. Wideband channels are assumed to begrouped next to each other, narrowband channels next to each other. A sufficient guard band 1 is assumedbetween the two channel groups, such that narrowband-to-wideband interference does not need to beseparately considered.Table 5-1: Basic system parametersParameter WB Mode NB Mode Units/NotesCenter frequency 5 5 GHzTotal system BW

WINNER D2.5 v1.0To analyse interference in various RF system scenarios, one needs to estimate the minimum attenuationfrom AP transmitter to MT receiver (including cables and body losses) and vice versa, so-called AP-MTminimum coupling loss 2 . A minimum coupling loss of 71.5 dB is here assumed, based on the 5 GHzfrequency band, educated guesses for cables losses, antenna gains etc, and an “urban street”-scenario,where AP height is 15 m from ground, MT height is 1.5 m, and there is 15 m separation between the APand the MT.The following initial assumptions for AP and MT output powers have been made:AP maximum output power +43 dBmMT maximum output power +23 dBmAP receiver noise figure +6 dBMT receiver noise figure +9 dBError vector magnitude (EVM) is used as a metric for RF performance. The required EVM is a systemparameter and depends on issues such as coding, modulation, and the MIMO case. Here, an EVM targetof -14 dB, corresponding to modulation 16-QAM at raw bit-error rate ~ 10 -2 , has been assumed.5.3.2 Transmitter requirements5.3.2.1 Output powerMT maximum output power is assumed to be +23 dBm. This output level results as a trade-off betweenthe static DC power consumption of the PA, the OFDM waveform, the restrictions for adjacent-channelpower leakage, and the feasible activity times. A static DC power of 2 W is assumed for the PA.Continuous transmission should be avoided because this would decrease the available peak power.Transistor level simulations/implementations are needed to see if this value is possible.AP maximum output power is assumed to be +43 dBm.5.3.2.2 AP TX noise floorThe requirements for noise floor of the AP transmitter follows from that the transmitter must not preventa closely located MS from receiving a weak signal from another AP in the adjacent channel. The MS seesthe noise floor from the close-by AP as interference on the wanted channel. In the most extreme case, theMT is at minimum coupling distance and the wanted signal is at sensitivity level. To push the TX noisebelow the thermal noise floor by some margin,(AP TX noise floor [dBm/Hz]) ≤ (MT RX noise floor [dBm/Hz])+ (minimum AP-MT coupling loss [dB]) – (multiple interference margin [dB]).With MT RX noise floor = thermal noise floor + noise figure = -165 dBm / Hz, and multiple interferencemargin = 7 dB, one obtains: AP TX noise floor ≤ -100.3 dBm/Hz (for synchronous network) 3 . Therequirement is the same for WB and NB modes.5.3.2.3 MT TX noise floorThe requirement for noise floor of MT transmitter follows from similar reasoning as for AP transmitter,only with MS and AP reversing places. Hence,(MT TX noise floor [dBm/Hz]) ≤ (AP RX noise floor [dBm/Hz])+ (minimum AP-MT coupling loss [dB]) – (multiple interference margin [dB]).With AP RX noise floor = thermal noise floor + noise figure = -168 dBm / Hz, and multiple interferencemargin = 7 dB, one obtains: MT TX noise floor ≤ -103.3 dBm/Hz (for synchronous network) 4 . Therequirement is the same for WB and NB modes.2 In unsynchronous network, also AP-AP and MT-MT minimum coupling losses would need to be considered. Here,MT-MT coupling loss has been assumed 37 dB (assuming 0.5 m MT-MT separation), and the value 20 dB hasbeen used for the AP-AP coupling loss.3 For unsychronous network, the dominating case is AP-AP interference, and the resulting requirement is that (AP TXnoise floor [dBm/Hz]) ≤ (thermal noise floor) + (AP NF) + (AP-AP coupling) – (margin) = -155 dBm/Hz. Suchperformance seems very difficult to achieve without filtering efforts.Page 93 (121)

WINNER D2.5 v1.05.3.2.4 Adjacent channel power ratioThe requirements for AP and MT TX adjacent-channel power ratio (ACPR) follow from the sameargument as those for the noise floor. Hence, they can be obtained simply as the ratio between themaximum output power and maximum allowed noise floor integrated over one channel.For analysing the RF requirements due to adjacent-channel interference, a multiple interference margin of3 dB is used. For AP, this yields maximum adjacent-channel power –96.3 dBm/Hz, corresponding to –17.1 dBm in WB mode and –26.1 dBm in NB mode. With maximum output power +43 dBm, the ACPRrequirements are then 60 dB in WB mode and 69 dB in NB mode.For MT, the maximum adjacent-channel power is –99.3 dBm/Hz, giving integrated power –20.1 dBm inWB mode and –29.1 dBm in NB mode. With maximum output power +23 dBm, the ratio is 43 dB in WBmode and 52 dB in NB mode.Unfortunately, from the point of implementation these values are too stringent. To alleviate Tx design, inparticular to reduce PA power consumption, the requirements must be relaxed significantly. Both thecalculated values and estimated feasible relaxed values are listed in Table 5-2. If the transmitter is nottransmitting at full power, ACPR can be relaxed proportionally.Table 5-2: AP and MT TX ACPR requirementsAP WB AP NB MT WB MT NB CommentCalculated requirement 60 dB 69 dB 43 dB 52 dB unfeasibleRelaxed specification 45 dB 45 dB 39 dB 39 dB FeasibleCorrect value of the ACPR is critical from the power consumption point-of-view, since the ACPRrequirement determines the linearity requirement of the PA and, eventually, PA power consumption. Withrelaxed ACPR requirement, high output power can be achieved with good efficiency. Proper ACPRvalues should be found by system level simulation so that ACP does not degraded too much systemcapacity. This can be done, for example, with static system simulations. ACPR 39 dB is a toughrequirement for the MT already and the value should be further relaxed as much as possible. As areference, the value for 802.11a is 25 dB and WCDMA 33 dB. The difference to 802.11a is due toWLAN not being a cellular system. The WCDMA value also results from relaxing the strictly calculatedspecification; it may prove possible to further decrease also the WINNER requirement, but as said thisrequires further studies.5.3.2.5 Spectrum masksSpectral masks have been defined based on the noise floor and ACPR requirements. A measurementbandwidth of 100 kHz has been selected. The far-limit points of the radiation mask follow from the noisefloor requirement, bandwidth, and maximum TX power, as summarised in the following table:Table 5-3: Conversion of TX noise floors to spectrum mask far-limit requirementsAP WB AP NB MT WB MT NB Unit / CommentMaximum Tx power +43 +43 +23 +23 dBmSignal bandwidth 83.2 10.4 83.2 10.4 MHzMaximum Tx noise floor -100.5 -100.5 -103.5 -103.5 dBm/Hz, synch. TDDMaximum Tx power/100 kHz +13.8 +22.8 -6.2 +2.8 dBmMaximum noise power/100 kHz -50.5 -50.5 -53.5 -53.5 dBmMaximum noise vs max power -64.3 -73.3 -47.3 -56.3 dBcThe transition part of the spectrum masks have been defined to conform to spectral shapes obtained fromPA simulations, subject to boundary conditions that the relaxed ACPR requirements from Table 5-2 andthe noise floor limits from Table 5-3 are satisfied. It would be better if ACPR requirement were relaxedeven more to make the implementation easier. The mask points are given and explained in Table 5-4.4 For nonsynchronous network, the dominating case is MT-MT interference, and the requirement is that (MT TXnoise floor [dBm/Hz]) ≤ (MT thermal noise floor) + (MT NF) + (MT-MT coupling) –(margin) = -134 dBm/Hz.Allowing for several MT interferers would increase the requirement further.Page 94 (121)

WINNER D2.5 v1.0Table 5-4: AP and MT spectrum masks: dBc values, and how they were determinedMask Frequency offset, Spectrum valueCommentPoint (case when applies) (case when applies)A 51.2 MHz (AP WB) 0 dBc In the middle of channels6.4 MHz (AP NB)51.2 MHz (MT WB)6.4 MHz (MT NB)B 60.8 MHz (AP WB)7.6 MHz (AP NB)-39 dBc (AP WB)-39 dBc (AP NB)Beginning of the adjacent channel; satisfiesACPR criterion.60.8 MHz (MT WB)7.6 MHz (MT NB)-33 dBc (MT WB)-33 dBc (MT NB)C 1 83.2 MHz (AP WB) -44 dBc (AP WB) Spectrum slope transition point.10.4 MHz (AP NB)83.2 MHz (MT WB)10.4 MHz (MT NB)-44 dBc (AP NB)-38 dBc (MT WB)-38 dBc (MT NB)D 1 155 MHz (AP WB) -64.3 dBc (AP WB) Simulated PA spectrum slope hits noise floor.23.4 MHz (AP NB)116 MHz (MT WB)18.5 MHz (MT NB)-73.3 dBc (AP NB)-47.3 dBc (MT WB)-56.3 dBc (MT NB)1According to preliminary PA simulations, a transition in the slope of the output spectrum occurs at an offset ofapproximately one bandwidth. The slope is assumed about 15 dB/bandwidth first, and then 19 dB/bandwidth.Figure 5-8: TX Spectrum masks. For convenience, allowed ACPR is shown as pronounced5.3.2.6 Transmitter EVMTransmitter (and receiver) EVM requirement are determined from the SNR requirement for the differentmodulation and coding states (MCS). The total EVM at the decoder is the sum of the EVM generated bythe TX and RX. Since it is more difficult to make the TX EVM very low, the total EVM budget shouldallow the TX EVM to dominate. In addition, the EVM requirements for the AP TX and RX should be fewdB more difficult than those for the MT. EVM (EVM for TX and sensitivity for RX) requirements can bePage 95 (121)

WINNER D2.5 v1.0defined for the system when link simulations are ready and when different modulation and coding states(MCS) are defined.5.3.2.7 Power ramp-up and ramp-downThe duplexing scheme and the system in general should be constructed keeping the following hardwarerequirements in mind:• When changing frequency, the synthesizer needs about 90 µs for locking. Faster locking ispossible, but if would increase the complexity of the synthesizer unnecessarily.• Switching between TX/RX requires some time. A 10 µs guard time should be sufficient. This is anguesstimate and further studies should be done to find adequate switching time for Winner airinterface.• TX power ramp-up time is dominated by the NB mode. The ramp-up time depends on thespectrum mask and implementation. Something like 2.5 µs should be implementable.• It takes some time from MT receiver automatic gain control (AGC) to finds the proper gain andsettle. The settling time is the highest in the NB mode, when the received signal is very strongand the AGC initially has maximum gain. In this case, at least 3.0 µs should be reserved forAGC settling.5.3.3 Receiver requirements5.3.3.1 AP receiver dynamic rangeIn synchronous network, the maximum signal power on one channel(max. signal [dBm]) = (MS TX power [dBm]) – (AP-MT min. coupling loss [dB])With MS maximum TX power +23 dBm and minimum AP-MT coupling 71.5 dB, the maximum APantenna power on one frequency channel is –48.5 dBm. However, interference from other base stationsand potential co-cited systems can change the situation radically.Minimum signal level depends on the noise floor and required minimum SNR. However, to be able toreceive the minimum-power with the required SNR, the sensitivity of receiver must be of the order of thenoise power. Hence,(RX noise power [dBm]) = (thermal noise [dBm/Hz]) + (NF [dB]) + 10 lg (bandwidth [Hz]).With NF = 6 dB, the integrated noise is –89 dBm in the WB mode and –98 dBm in the NB mode.5.3.3.2 MT receiver dynamic rangeIn synchronous network 5 , the maximum signal power on one channel(max. signal [dBm]) = (AP TX power [dBm]) – (AP-MT min. coupling loss [dB])With AP maximum TX power +43 dBm and minimum AP-MT coupling 71.5 dB, the maximum MTantenna power on one frequency channel is –28.5 dBm.Minimum signal level depends on the noise floor and required minimum SNR. However, to be able toreceive the minimum-power with the required SNR, the sensitivity of receiver must be of the order of thenoise power. Hence,(RX noise power [dBm]) = (thermal noise [dBm/Hz]) + (NF [dB]) + 10 lg (bandwidth [Hz]).5 In unsynchronous network, the dominating case is MT-MT interference. With maximum MT Tx power +23 dB anda MT-MT minimum coupling loss 37 dB, the maximum received signal in one channel is –14 dBm.Page 96 (121)

WINNER D2.5 v1.0The integrated noise power is –86 dBm in the WB mode and –95 dBm in the NB mode.5.3.3.3 Linearity requirementsThe linearity requirements follow from the power levels of the interferer signals, which the receiver mustbe able to tolerate in the each adjacent channel while receiving a weak wanted signal. In principle, themaximum adjacent-channel powers are the above-mentioned values –28.5 dBm for MT and –48.5 dBmfor AP, and the wanted signal might be at sensitivity level. In practice, this would result in technicallyunfeasible requirements for, e.g., MT linearity and selectivity. Moreover, relaxation of the TX ACPRrequirements discussed Ch. 5.3.2.4 limits also the maximum feasible adjacent-channel power. Hence, theblocking power requirements and, consequently, linearity and selectivity requirements, need to be relaxedto technically feasible limits, and 3 dB degradation in the EVM of the wanted signal is to be allowed inblocking scenarios. As a consequence, there is a finite probability of the receiver not being able to operatebecause of the interference. Estimating the statistics requires extensive work and will not be done here.Relaxed blocking powers, based on which the requirements will be calculated, are listed in Table 5-5.Table 5-5: Maximum Rx blocking power: requirements and technical limitsAP WB AP NB MT WB MT NB CommentACP1 -48.5 dBm -48.5 dBm -28.5 dBm -28.5 dBm system requirement-49.8 dBm -58.8 dBm -40.8 dBm -49.8 dBm limited by TX ACPR-52 dBm -61 dBm -45 dBm -53 dBm requirement, with some marginACP2 -48.5 dBm -48.5 dBm -28.5 dBm -28.5 dBm system requirement-41.5 dBm -41.5 dBm -21.5 dBm -21.5 dBm limited by TX mask-25 dBm -25 dBm -25 dBm -25 dBm limited by IIP3 = -15 dBm-45 dBm -45 dBm -32 dBm -32 dBm requirement, with some marginThe non-linearity of the receiver is assumed to consist of second- and third-order non-linearity,characterised by respective (out-of-band) input intercept points IIP2 and IIP3. The effect of the linearityon OFDM signal reception in the context of the dual-band TDD concept has been studied with blockingsimulations. In these simulations, the power of the wanted signal was set to the level of thermal noise +16 dB (SNR) + 3 dB margin, and a set of blockers was applied. The level of distortion was studied asfunctions of IIP2, IIP3, and blocking powers; a signal degradation of 3 dB was to be allowed.In the test for second-order non-linearity, a single blocking signal was located at the second adjacentchannel. For ideal-like test signals and ignoring third-order non-linearity, a reasonable IIP2 ≥ +35 dBmwas found sufficient to handle blocking powers up to –28.5 dBm and more.The third-order non-linearity manifests itself as crossmodulation of a single blocker with the wantedsignal itself, and as intermodulation of two or more blockers. The resulting intermodulation distortion wasstudied with two-tone test simulations, where two blockers of equal power are located at the second andthe fourth adjacent channel. The IIP3 requirement for blocking powers of the order of –28 dBm wasfound to be IIP3 ~ 5-10 dBm. Unfortunately, this is unfeasible for implementation with present RFICtechnologies 6 . However, note that the test case corresponds to the RX being at minimum distance to twointerfering TX’s, while the wanted TX is far away. Such a scenario is not likely to occur often. Withcurrent RFIC technologies, an IIP3 ~ -15 dBm seems reasonable. According to simulations, this wouldenable handling two-tone blocker powers ~ –40 dBm (WB) and –42 dBm (NB).The third-order nonlinearity was also found to limit the selectivity of the receiver throughcrossmodulation of the blocker and the wanted signal. With reasonable values IIP3 ~ -15 dBm and IIP2 ~35 dBm, simulations indicate that single-tone blocking signal powers up to ~ –25 dBm in the secondadjacent channel could be tolerated.5.3.3.4 SelectivityThe receiver must be able to attenuate the interference signals in the other channels sufficiently below thenoise floor. Hence,(Selectivity [dB]) = (max. interference [dBm]) – (RX noise floor [dBm]) + (margin [dB]).6 For nonsynchronous network the corresponding numbers are even more unfeasible, for example IIP2 ≥ +70 dBm.Page 97 (121)

WINNER D2.5 v1.0The selectivity can be distributed among analog and digital filters. Taking maximum interference powerof –28.5 dBm and 12 dB margin, we obtain MT selectivity ≥ 69/78 dB in WB/NB mode.The selectivity for the first adjacent channel is an exception, since the relaxation of the TX ACPR directlylimits the maximum power that can be tolerated in the adjacent channel: the spectral shoulders of theblocker extend to the wanted signal, see Figure 5-9. Hence, the AP TX ACPR requirement sets an upperlimit also for the maximum adjacent-channel power in MT RX, and the MS TX ACPR requirements setsan upper limit for the maximum ACP in AP RX. These limit values are listed in Table 5-5. Once themaximum ACP values are known, the corresponding selectivities follow as usual.A further complication arises from that selectivity is usually tested with modulated single-tone blockingtest, wherein the test signals have almost ideal spectrum (high ACPR). For such almost ideal signal, theselectivity is limited by nonlinearity through intermodulation and crossmodulation. Then, sufficientmargin must be added to the test case blocking power to guarantee that the selectivity is sufficient also forfield conditions. The ACP requirements –38 dBm (WB) and –43 dBm (NB) were found sufficient forboth AP and MT.Figure 5-9: Adjacent-channel blockers and selectivity. RX filtering suppresses adjacent-channelinterference, but not inband-interference due to the TX ACPR of the blocker5.3.4 Synthesizer5.3.4.1 Phase-noiseIn-loop phase noise should be less than –71 dBc/Hz to not degrade the EVM of the signal (EVM =-30dB). This value is dependent on the EVM budget of the RX and TX and used waveform.The noise floor of the synthesizer dominates TX phase noise. Consequently, the TX phase noiserequirements follow from the noise floor requirements determined in Chs. 5.3.2.2 and 5.3.2.3 (-100/-103dBm/Hz for AP/MT, respectively). With output power +43/+23 dBm (AP/MT), the noise floor of the PLLshould be less -143/-126 dBc/Hz (AP/MT), with some margin.The phase-noise requirements set by the RX arise from interference considerations. Demanding that thedownconverted interference signal remains below the noise floor yields(phase noise [dBc/Hz @ offset]) < (RX noise floor [dBm/Hz]) – (interference [dBm]).The relaxed blocking powers listed in Table 5-5 are used. A safety margin of 9 dB is added. The resultingphase noise requirements are shown in Table 5-6. The collected, dominating results are shown in Table5-7.Page 98 (121)

WINNER D2.5 v1.0Table 5-6: RX phase noise requirements due to blockersOffset Blocker Phase noise + 9 dB margin CommentAP NB 2.4 MHz -61 dBm -107 – 9 = -116 dBc/Hz noise floor -168 dBm/HzAP NB 15.2 MHz -45 dBm -123 – 9 = -132 dBc/Hz noise floor -168 dBm/HzAP WB 19.2 MHz -52 dBm -116 – 9 = -125 dBc/Hz noise floor -168 dBm/HzAP WB 121.6 MHz -45 dBm -123 – 9 = -132 dBc/Hz noise floor -168 dBm/HzMT NB 2.4 MHz -53 dBm -112 – 9 = -121 dBc/Hz noise floor -165 dBm/HzMT NB 15.2 MHz -32 dBm -133 – 9 = -142 dBc/Hz noise floor -165 dBm/HzMT WB 19.2 MHz -45 dBm -123 – 9 = -132 dBc/Hz noise floor -165 dBm/HzMT WB 121.6 MHz -32 dBm -133 – 9 = -142 dBc/Hz noise floor -165 dBm/HzTable 5-7: Collected PLL requirementsQuantity AP MT UnitPhase-noise within loop bandwidth ≤ -71 ≤ -71 dBc/Hz, EVM –30 dBPhase-noise at 2.4 MHz offset ≤ -116 ≤ -121 dBc/HzPhase-noise at 15.2 MHz offset ≤ -132 ≤ -142 dBc/HzLocking time ≤ 45 ≤ 45 µs5.3.4.2 Locking timeLocking time is defined to be 2*(OFDM symbol duration + CP) = 45 µs. Shorter settling time is difficultto implement. Already this is difficult to implement with conventional integer-N type of synthesizers.When defining allocation in the super (MAC) frame, it should be taken into account that shorter transitiontimes than 45 µs are not allowed between two difference frequencies for the mobile device. AP has it’sown synthesizers for RX and TX meaning that frequencies remains the same all the time.5.3.5 Consequences for selected duplex schemes5.3.5.1 TDD and dual-band TDDIn the above, the RF requirements were derived for synchronous TDD network, and the requirements forunsynchronous network were occasionally provided in the footnotes.The requirements for the unsynchronous network, e.g. TX noise floor, RX dynamic range, and RXlinearity, were found technically unfeasible. This doesn’t mean an unsynchronous system would be totallyinoperative, but interference in an unsynchronous network causes severe performance degradation andloss of area coverage. To decrease the interference, guard bands may be introduced between channels.This helps with ACPR-originated problems, but not with problems arising from AP’s or MT’s beingclosely located, in particular TX noise floors and blocking. Only channel-specific RF filtering or spatialdecoupling (not allowing closely located AP’s or even MT’s!) come to mind as solutions. Introducing amultitude of RF filters makes the terminal expensive and large. Furthermore, such filters would requiretransition bands between the channels, radically decreasing the spectral efficiency of the system.In dual-band TDD scheme, it is beneficial to group WB channels into one band and NB channels intoanother band. This improves the capability of the RX to receive weak WB signals in the presence ofstrong NB blockers. According to first estimates, a guard band of the order of 70 MHz should besufficient for this purpose. In future, system simulations should be used to determine the benefits ofincreasing the NB-WB isolation with additional filtering.5.3.5.2 RF requirements for FDDThe requirements for an FDD network can be derived from the requirements for synchronous andunsynchronous TDD network, with the requirements arising from AP-MT interference interpreted toapply within UL band or DL band, and with the requirements arising from AP-AP and MT-MTinterference interpreted to dominate UL-to-DL and DL-to-UL requirements. In FDD also the latterPage 99 (121)

WINNER D2.5 v1.0requirements are feasible, since UL and DL occur at different frequencies, and the isolation can beimproved with a duplex filter.For convenience, the requirements and their interpretation have been collected to Table 5-8. An additionalrequirement in FDD system is that the duplex filter must prevent the TX from disturbing the RX on thesame piece of equipment. Firstly, the isolation of the duplexer in the RX band must be sufficient tosuppress TX noise floor below RX noise floor. Secondly, duplex isolation in the TX band must beoptimised together with RX linearity to prevent TX leakage from blocking the receiver.Table 5-8: Equivalent RF requirements for an FDD systemRF Parameter WB NB Unit, CommentAP TX output power +43 +43 dBm, initial assumptionAP TX noise floor -100.3 -100.3 dBm/Hz, in DL band-155 -155 dBm/Hz, in UL band (with duplexer)-168 -168 dBm/Hz, from TX to RX in UL band (with duplexer)AP TX ACPR 60 69 dB, system requirement45 45 dB, relaxed specificationAP RX noise floor -89 -98 dBm, assuming NF = 6 dBAP RX max. power -48.5 -48.5 dBm, one channelAP RX blockers +43 +43 dBm, from TX within DL band (with duplexer)-48.5 -48.5 dBm, ACP, system requirement-52 -61 dBm, ACP, relaxed specification-45 -45 dBm, ACP2AP RX linearity, IIP2 +35 +35 dBm, UL band+171 +171 dBm, DL band (with duplexer)AP RX linearity, IIP3 -15 -15 dBm, UL band, relax specification+87 +87 dBm, DL band (with duplexer)AP Synthesizer As in Table 5-7.AP Duplex isolation 68 68 dB, TX-to-RX in DL bandMT TX output power +23 +23 dBm, initial assumptionMT TX noise floor -103.3 -103.3 dBm/Hz, in UL band-134 -134 dBm/Hz, in DL band (with duplexer)-165 -165 dBm/Hz, from TX to RX in DL band (with duplexer)MT TX ACPR 43 52 dB, system requirement39 39 dB, relaxed specification (still maybe too high)MT RX noise floor -86 -95 dBm, assuming NF = 9 dBMT RX max. power -28.5 -28.5 dBm, one channelMT RX blockers +23 +23 dBm, from TX within UL band (with duplexer)-28.5 -28.5 dBm, ACP, system requirement-45 -45 dBm, ACP, relaxed specification-32 -32 dBm, ACP2MT RX linearity, IIP2 +35 +35 dBm, DL band+131 +131 dBm, UL band (with duplexer)MT RX linearity, IIP3 -15 -15 dBm, DL band, relax specification+57 +57 dBm, UL band (with duplexer)MT Synthesizer As in Table 5-7.MT Duplex isolation 48 48 dB, TX-to-RX in UL bandInitial duplex filter requirements can be derived as follows. For AP output power +43 dBm, the TDDnoise floor requirement –100.5 dBm/Hz is already rather strict. Hence, the duplex filter must suppress theTX noise below RX noise floor –168 dBm/Hz, yielding isolation requirement 68 dB in the UL band.Assuming AP receiver linearity is sufficient to handle blocking power –25 dBm, the requirement for TXsignal suppression gives the same 68 dB. For MT, it seems necessary to reduce the TX noise floor bycircuit design to alleviate the isolation requirement in DL band. As to UL isolation, with output power+23 dBm and assuming again that from linearity perspective blocking powers –25 dBm are acceptable,the minimum UL band isolation requirement is 23+25 = 48 dB. The equivalent IIP2 and IIP3 can becalculated straightforwardly.Page 100 (121)

WINNER D2.5 v1.0A sufficient guard band must be allocated between the UL and DL bands such that the duplex filter canreach the required isolation at the RX band. The feasible duplex distance depends somewhat on the filtertechnology and also on the out-of-band spectral emission and blocking requirements. To have some initialunderstanding on the achievable AP filter performance, 6-resonator and 8-resonator filters wererespectively approximated with 12 th and 16 th order Chebychev prototype filters with ripple 0.1 dB. TheUL/DL bands were assumed to consist of 3-5 102.4 MHz channels around center frequency 5.0 GHz. Thefrequency responses were calculated, and the frequency offset required to achieve 70 dB suppression wasdetermined. For 12 th order filters, the guard bands were about 290, 385, and 475 MHz for 3, 4, and 5channel bands. For 14 th order filter, the required guard band was about 240 MHz for 5 channels.On the terminal side, the required guard bands can be assumed to be at least of the same order. The issueis complicated by the fact the miniaturised filters are needed for terminal. However, the SAW and BAWfilter technologies which are widely employed in 2G terminals are limited to relative bandwidths ~3-5%,and cannot cover more than one or two wideband channels. Hence, either several such filters must beused, which is expensive (and even more so for MIMO transceivers), or alternative technologies, such asvarious ceramic technologies, must be resorted to. Unfortunately, ceramic filters have a tendency to bemore bulky and to show more modest close-in suppression than their acoustic competitors.5.3.5.3 Half duplex FDDFrom AP perspective, the RF requirements for a half duplex network are the same as those for an FDDnetwork discussed in the previous section.From MT perspective, the requirements are the same as for FDD, except that there is no demand to TX-RX isolation: this alleviates the requirements for duplex filter, TX noise floor, and RX linearity.5.4 RF dictionaryThis section is added to help the readers, who are not familiar with the basic RF terms, to help them betterunderstand the contents of this chapter.Error vector magnitude (EVM)A metric for signal degradation in the radio link or a subsystem of it. EVM can be defined as therms-averaged error of a complex-value baseband signal as compared to reference signaltransmitted through an ideal link, normalised to the root-mean-squared power of the signal. Fornoise-like error, EVM is the inverse of the signal-to-noise ratio.Phase-lock loop locking timePhase noiseTime required by the synthesizer to settle to a new frequency.Ideally, synthesizer produces pure sinusoidal tone. In practice, fluctuations occur. They caninterpreted as a noise component added to the phase of the sinusoidal—phase noise. The phasenoise widens the spectrum of the LO signal. In transmitters, phase noise degrades modulationaccuracy and contributes to the output spectrum. In receivers, the main problem is the resultingspectral widening of downconverted interference signals: if an interference signal outside thewanted channel is strong enough, the widened tails of the interference spectrum extend to thewanted channel and appear as in-band interference.Noise figure (NF)RX noise floorA metric for the additional noise added to signal by the hardware component under question.Noise figure is defined as the ratio of the signal-to-noise ratios in the output and input of thecomponent, under condition that the input noise results from a matched resistor at 290 Ktemperature (input noise is thermal noise at room temperature).Page 101 (121)

WINNER D2.5 v1.0The baseline noise power appearing in the output of (analog) receiver, expressed as equivalentinput noise in the antenna. The output interface is typically placed at the input of the analog-todigitalconverters. The noise floor consists of thermal noise from the radio channel, and of noiseoriginating in the receiver itself, the latter quantity being commonly expressed through the noisefigure of the receiver.Receiver selectivityThe capability of the receiver to suppress unwanted interference components appearing outsidethe wanted frequency channel. Selectivity consists of the combined effect of the analog anddigital filters in the system. It is also affected by the analog-to-digital converter sampling rate.Receiver linearityAll analog signal processing is to some extent nonlinear. Non-linearity gives a rise to signaldistortion via crossmodulation and intermodulation, and limits the capability of the receiver toresolve weak input signals when strong interference occurs in the other channel/channels.Receivers typically need to be quasi-linear over the dynamic range of interest, such that a thirdorderTaylor series expansion is sufficient to characterise the non-linearity. The second and thirdorder non-linearities are commonly expressed through respective input intercept points (IIP).Adjacent channel power (ACP)Unwanted signal power integrated over the adjacent channel. Receivers are usually mostsensitive to interference in the first adjacent channel. This is because channel filters usually havenot reached their maximum suppression at the corner of the adjacent channel, and because of thespectral regrowth of the interference signal to the wanted channel due to non-linearity.Transmitter adjacent channel power ratio (ACPR)To achieve high efficiency, it is beneficial to operate transmitters and, in particular, poweramplifiers as close to saturation as feasible. As a consequence of the resulting strong nonlinearity,the transmitted signal experiences spectral regrowth and power leaks to the adjacentchannels. ACPR is defined as the ratio of the unwanted power in the adjacent channel to thetransmitted signal power in the wanted channel. Because the power transmitted to adjacentchannels appears directly as interference to users in those channels, ACPR must be strictlycontrolled by specifying spectrum masks.Transmitter noise floorWideband noise floor generated by the transmitter. Noise originates in Tx chain, and the poweramplifier amplifies it. Typically the out-of-band noise floor is filtered out with a RF filter afterthe PA. In full duplex FDD it is important to have low noise floor since the noise at RX bandwill deteriorate the sensitivity of the receiver. To allow simultaneous operation of different radiosystems in the same geographical area at different frequencies, the noise floors of each systemmust be strictly regulated via spectrum masks.Page 102 (121)

WINNER D2.5 v1.06. Coexistence of duplex schemesSpectrum arrangements and coexistence for multiple duplex schemes are considered in this section. Thereason for the coexistence considerations is that WINNER system concept may need to support multipleduplex schemes to increase the flexibility (configurability) of the system for deployment in differentenvironments. For example, different duplex schemes may be seen suitable for short-range and wide-areascenarios. This and desire of continuous coverage would require multiple duplex schemes to coexist inthe same geographical area, operated by either one or multiple operators. Hence, it is important toconsider feasibility as well as limitations of coexistence. In the following, it is assumed that the multipleduplex schemes are allocated on the adjacent frequency bands causing the problems of coexistence.The purpose of the section is to study the feasibility of the coexistence of duplex schemes. The problem isapproached by providing guard band estimates in respect of physical separation and attenuation betweenaggressing transmitter and victim receiver with different coexistence scenarios. In other words, indicativeguard band estimates, based on some numerical examples, are used solely for the purpose of comparingcoexistence scenarios. The approach concentrates mainly on the transmitter requirements, and theimpacts of coexistence on the receiver requirements are not addressed.In the section, interference and coexistence scenarios considered are presented first, followed byintroduction of numerical examples, calculation of indicative guard band estimates, and comparisons oncoexistence scenarios.6.1 Considered interference and coexistence scenariosThe considered scenarios are limited to coexistence of two duplex schemes in the same geographical area.Seven different duplex concepts are introduced in Section 2.5, which creates total of 21 differentcoexistence pairs. To limit the number of considered coexistence pairs, two duplex concepts wereexcluded from the study: uplink oriented hybrid and band switching FDD. The results for the bandswitching FDD can be rather easily derived from the coexistence results with pure TDD and, thus, bandswitching FDD was excluded. The same holds also for the uplink oriented hybrid, although propercombination of pure TDD and FDD results is required. The coexistence cases considered are summarisedin Table 6-1. Some of the duplex concept pairs have similar coexistence properties at this stage, since thepossible differences in the properties are induced by the inevitable differences in the radio interfacesolutions developed for the duplex concepts later on. Therefore some of the duplex concept pairs areconsidered jointly. In the following sections, possible spectrum arrangements are presented for thecoexistence scenarios.CoexistencecaseFDD /(T+F)DDFDD / TDDFDD /DL hybridFDD /DB TDD(T+F)DD /TDD(T+F)DD /DL hybrid(T+F)DD /DB TDDTDD /DL hybridTDD /DB TDDTable 6-1: Scenarios for coexistence of duplex conceptsCoexisting duplex conceptsPure FDD &half duplex FDDPure FDD &pure TDDPure FDD &downlink oriented hybridPure FDD &dual band TDDHalf duplex FDD &pure TDDHalf duplex FDD & downlinkoriented hybridHalf duplex FDD &dual band TDDPure TDD &downlink oriented hybridPure TDD &dual band TDDDL hybrid / Downlink oriented hybrid & -Comments----Similar characteristics as in FDD / TDD, differencesinduced by radio interface technologies.Similar characteristics as in FDD / DL hybrid,differences induced by radio interface technologies.Similar characteristics as in FDD / DB TDD, differencesinduced radio interface technologies.-Coexistence of multiple synchronised TDD modes isincorporated to dual band TDD concept. Implications ofunsynchronised TDD carriers are addressed in previoussection. It is difficult to see any need for this scenario.Page 103 (121)

WINNER D2.5 v1.0DB TDDdual band TDD6.1.1 Coexistence scenario for pure and half duplex FDD conceptsThe spectrum arrangement considered for the combination of pure and half duplex FDD concepts ispresented in Figure 6-1. The arrangement is due to the duplex distance and the paired bands required byboth duplex concepts. The required duplex distance is composed of the duplex gap appearing in the figureand other carriers that are between the paired uplink and downlink carriers of the given terminal.Additionally to that, guard band G2 is designed to guarantee sufficient attenuation for BS-to-BS and MTto-MTinterference. The requirements for the guard bands G1 and G3 between frequency bands A and Bas well as C and D depend on MT-to-BS and BS-to-MT interference characteristics, respectively.A G1 B G2CG3D(T+F)DD ULFDD ULDuplex gap(T+F)DD DLFDD DLFrequencyFigure 6-1: Spectrum arrangement for coexisting pure and half duplex FDD6.1.2 Coexistence scenario for pure FDD and TDD conceptsThe spectrum arrangement considered for the combination of pure FDD and TDD concepts is presentedin Figure 6-2. In the arrangement, the TDD band is allocated between FDD bands due to the duplexdistance required by FDD. A paired allocation of FDD carriers is assumed, that is, the width of band A isequal to band C (since no fixed DL/UL asymmetry is promoted). However, the bandwidths of FDD andTDD carriers do not need to be same, and the other duplex scheme may be a scaled WINNER mode withnarrower carrier bandwidths.The spectrum arrangement for coexistence of half duplex FDD and TDD concepts is similar.AG1BG2CFDD ULTDDFDD DLFrequencyFigure 6-2: Spectrum arrangement for coexisting pure FDD and TDD6.1.3 Coexistence scenario for pure FDD and downlink oriented hybrid conceptsThe spectrum arrangement for coexisting pure FDD and downlink oriented hybrid concepts is presentedin Figure 6-3. Although the arrangement resembles the one with coexistence of pure and half duplexFDD, the requirements for the guard bands G1 and G2 are different. Most significantly, guard band G1needs to guarantee sufficient attenuation for AP-to-AP interference in addition to the MT-to-APinterference.The spectrum arrangement for coexistence of half duplex FDD and TDD concepts is similar.Page 104 (121)

WINNER D2.5 v1.0AFDD ULG1BDL orientedhybridUL / DLG2CFDD DLG3DDL orientedhybridDLFrequencyFigure 6-3: Spectrum arrangement for coexisting pure FDD and downlink oriented hybrid concepts6.1.4 Coexistence scenario for pure FDD and dual band TDD conceptsThere are several spectrum arrangements for coexistence of FDD and dual band TDD due to two unpairedbands (NB and WB) in the dual band TDD concept. These are presented in Figure 6-4. In the spectrumarrangement A, the guard bands G1 and G3 have similar requirements as guard bands in Section 6.1.2,while guard band G2 is inherent for the dual band TDD concept. It is assumed in the following that thecarriers on the NB and WB of dual band TDD are synchronised. Thus, guard band G2 will be consideredto attenuate only MT-to-AP and AP-to-MT interference. In the spectrum arrangements B and C, all guardbands have similar requirements as in Section 6.1.2.One should note that it is possible that the narrow band of dual band TDD concept is allocated on totallydifferent frequency range. In that case, the coexistence scenario reduces to the one with pure FDD andTDD.The possible spectrum arrangements for coexistence of half duplex FDD and dual band TDD concepts aresimilar.Figure 6-4: Spectrum arrangements for coexisting FDD and dual band TDDPage 105 (121)

WINNER D2.5 v1.06.1.5 Coexistence scenario for pure TDD and downlink oriented hybrid conceptsThe spectrum arrangement is similar to the one in Section 6.1.2, with the DL band of downlink orientedhybrid allocated on band A and DL/UL band of downlink oriented hybrid on band C.6.1.6 Coexistence scenario for downlink oriented hybrid and dual band TDD conceptsIn this case, the spectrum arrangement is similar to the one in Section 6.1.4, with the UL/DL of downlinkoriented hybrid replacing the UL of pure FDD and the DL of downlink oriented hybrid replacing the DLof pure FDD.To summarise the scenarios, the interference types attenuated by the guard bands are tabulated in Table6-2 for the presented coexistence cases. One should note that in all cases the guard bands provide also apart of the duplex distance which is required in all coexistence cases. It should also be kept in mind thatthe cases FDD / DB TDD, (T+F)DD / DB TDD and DL hybrid / DB TDD reduce to FDD / TDD,(T+F)DD / TDD and DL hybrid / TDD cases, respectively, if the narrow band of the dual band TDD isallocated on different frequency band, e.g., at lower frequencies.Table 6-2: Interference types in the coexistence scenariosCoexistencecaseGuardband 1Guardband 2Guardband 3FDD / (T+F)DD MT-to-AP AP-to-AP, MT-to-MT AP-to-MTCommentsFDD / TDDor(T+F)DD / TDDFDD / DL hybridor(T+F)DD /DL hybridFDD / DB TDDor(T+F)DD /DB TDDAP-to-AP,MT-to-MT,MT-to-APAP-to-AP,MT-to-MT,MT-to-APAP-to-AP,MT-to-MT,MT-to-APAP-to-AP, MT-to-MT,MT-to-AP, AP-to-MTAP-to-AP, MT-to-MT,MT-to-AP, AP-to-MTArrangement A:MT-to-AP, AP-to-MTArrangement B:AP-to-AP, MT-to-MT,MT-to-APNo needAP-to-MTAP-to-AP,MT-to-AP,AP-to-MTIf NB and WB of DB TDDare not synchronised andhave the same switchingpoint , Arrangement A hasalso AP-to-AP and MT-to-MT interferenceTDD / DL hybrid AP-to-AP,MT-to-MT,MT-to-AP,AP-to-MTDL hybrid /DB TDDAP-to-AP,MT-to-MT,MT-to-AP,AP-to-MTArrangement C:AP-to-AP, MT-to-AP,AP-to-MTAP-to-AP, MT-to-MT,MT-to-AP, AP-to-MTArrangement A:MT-to-AP, AP-to-MTArrangement B:AP-to-AP, MT-to-MT,MT-to-AP, AP-to-MTArrangement C:AP-to-AP, MT-to-AP,AP-to-MTNo needAP-to-AP,MT-to-AP,AP-to-MTIf NB and WB of DB TDDare not synchronised andhave the same switchingpoint , Arrangement A hasalso AP-to-AP and MT-to-MT interference6.2 Example cases on coexistence interference and required guard bandsSome indicative values, e.g., on transmitter noise floor and guard band requirements are needed toreasonably compare different coexistence scenarios. To facilitate the comparisons, few example cases aredefined, based on which corresponding transmitter noise floor and guard band requirements aresimplistically calculated. These indicative values are then used for comparing and evaluating thefeasibility of different coexistence scenarios. Both wideband (~100 MHz) and (relatively) narrowband(~10 MHz) transmission are considered to obtain a reasonable coverage of possible scenarios.Page 106 (121)

WINNER D2.5 v1.06.2.1 Assumed parameters and example casesThe system parameters used in the following examples are mainly the same as in Section 5.3, with theparameters presented in Table 5-1. WINNER system is assumed to support two modes with signalbandwidths of 83.2 MHz and 10.4 MHz and guard bands of 19.2 MHz and 2.4 MHz between adjacentcarries. These modes are referred to as wideband (WB) and narrowband (NB) modes. The assumedtransmission powers, cable losses and antenna gains are presented in Table 6-3.Some example cases were defined as worst cases of coexistence interference. In the examples, thephysical separation between interfering transmitter and victim receiver was defined as short as can beexpected to appear with a reasonable probability. However, due to severity of AP-to-AP interference inthe case of co-located AP’s, an example case with restrictions on the AP separation is also considered.One should also note that no example of RS co-location is included to the examples, thus, indicating asignificant limitation to the RS locations. The example cases are listed in Table 6-4. Assumed minimumphysical separations and number of interferes are also presented in Table 6-4 together with correspondingcoupling losses and multiple interference margins. Coupling losses between interfering transmitter andvictim receiver were calculated based on cable losses, antenna gains and free space path loss at the carrierfrequency of 5 GHz withL c [dB] = 32.4 + 20*log(f [MHz]) + 20*log(d [km]) + C Rx [dB] + C Tx [dB] - A Rx [dB] - A Tx [dB]where L c is the coupling loss, f is the carrier frequency, d is the physical separation, C Rx and C Tx are thecable losses, and A Rx and A Tx are the antenna gains at the transmitter and receiver, respectively.Table 6-3: Transmission power, cable losses and antenna gainsMax outputpowerMax output spectral density Cable loss Antenna gain ReceiverNFNBWBAP +43 dBm -27.2 dBm/Hz -36.2 dBm/Hz 2 dB 8 dB 7 6 dBRS +33 dBm -37.2 dBm/Hz -46.2 dBm/Hz 0 dB3 dB(-3 dB towardsinterferingAP) 8MT +23 dBm -47.2 dBm/Hz -56.2 dBm/Hz 0 dB 0 dB 9 dB6 dBTable 6-4: Example cases with physical separations, coupling losses, and multiple interferencemarginsInterferencescenarioDescriptionPhysicalseparationCouplinglossNumber ofinterferesMultipleinterferencemarginAP-to-AP AP’s are co-located. 1 m 34.4 dB 1 0 dBAP-to-APAP-to-RS,RS-to-APAP-to-MTAP’s are located on buildingsacross a street or square.AP is at the height of 15 m,RS at the height of 6 m, 25 mhorizontal separation.AP is at the height of 15 m,MT at the height of 1.5 m,10 m horizontal separation.50 m /100 m68.4 dB /74.4 dB1 0 dB26.6 m 71.9 dB 1 0 dB16.8 m 64.9 dB 1 0 dB7 Relatively low antenna gain is assumed in the anticipation of smart antenna techniques which would reduce antennagain towards the interfering transmitter.8 Elevation angle towards the interfering AP is assumed to high.Page 107 (121)

WINNER D2.5 v1.0MT-to-AP - 16.8 m 64.9 dB 3 -4.8 dBRS-to-RSRS-to-MTRS antennas are locatedacross a street.RS is at the height of 6 m,MT at the height of 1.5 m, 5m horizontal separation20 m 66.4 dB 1 0 dB6.7 m 60.0 dB 1 0 dBMT-to-RS - 6.7 m 60.0 dB 3 -4.8 dBMT-to-MT (a)Three MT’s are in a row, e.g.,laptops on a meeting.0.5 m 40.4 dB 2 -3 dBMT-to-MT (b) User is in a dense crowd. 1 m 46.4 dB 3 -4.8 dB6.2.2 Transmitter noise floor requirementsTransmitter noise floor requirements were calculated by requiring that interference at the victim receiveris at the noise level in the example cases. Transmitter noise floor N Tx was obtained in similar manner as inSection 5.3.2 as a product of thermal noise floor, receiver noise figure NF Rx , coupling loss, and multipleinterference margin M I , that is,N Tx [dBm/Hz] = - dBm/Hz + NF Rx [dB] + L c [dB] + M I [dB].The resulting noise floor requirements are tabulated for AP, RS, and MT in Table 6-5-Table 6-7,respectively.Transmitter noise floor requirement for AP is -134 dBm/Hz in the case of co-located APs. This can beseen as an unfeasible requirement and, therefore, co-location of APs using different duplex concepts isnot considered further. Otherwise the transmitter noise floor for AP is -100 dBm/Hz due to AP-to-MTinterference. In the case of relay station, RS-to-MT interference sets the noise floor requirement to -105dBm/Hz. However, one should note that a minimum distance of 20 m is assumed between relay stations.Examples set tight noise floor requirements also to the mobile terminal. MT-to-RS interference requires 5dB tighter noise floor than MT-to-AP interference, that is, -113 dBm/Hz. This is a very tight requirement,and it indicates that MT-to-RS interference scenario needs to be carefully considered. As expected, MTto-MTinterference sets the tightest requirement, i.e., from -123 dBm/Hz to -128 dBm/Hz, which isunfeasible in practice.Table 6-5: Transmitter noise floor requirements for AP in interference examplesInterference scenarioAP-to-AP(co-located)AP-to-AP AP-to-RS AP-to-MTTransmitterfloornoise-133.6 dBm/Hz-99.6 dBm/Hz (50 m)- 93.6 dBm/Hz (100 m)-96.1 dBm/Hz -100.1 dBm/HzTable 6-6: Transmitter noise floor requirements for RS in interference examplesInterference scenario RS-to-AP RS-to-RS RS-to-MTTransmitter noisefloor-96.1 dBm/Hz -101.6 dBm/Hz -105.0 dBm/HzTable 6-7: Transmitter noise floor requirements for MT in interference examplesInterferencescenarioTransmitternoise floorMT-to-AP MT-to-RS MT-to-MT (a) MT-to-MT (b)-107.9 dBm/Hz -112.8 dBm/Hz -127.6 dBm/Hz -123.4 dBm/HzPage 108 (121)

WINNER D2.5 v1.06.2.3 Guard band requirementsThe guard bands required by the different interference scenarios were estimated based on the transmitternoise floor requirements, transmission powers in Table 6-3, and the spectrum mask presented in Section5.3.2.5. It was assumed that the spectrum values decrease 19 dB / bandwidth after the first bandwidthuntil it reaches the noise floor. The relative spectrum mask for the RS was assumed to be same as for theAP. In other words, relatively strict ACPR was assumed for the relay station. Guard band was defined asthe width of the frequency band between two adjacent signal bands, and it was required that transmissionspectrum reaches the noise floor on the beginning of the adjacent signal band, as illustrated in Figure 6-5.The estimates are presented both in relative and absolute terms in Table 6-8. It can be seen from the tablethat such strict guard band definition results in wide guard bands, in the order of one to three times thesignal bandwidth. The presented values prevent any coexistence of the duplex schemes without excessiveguard bands and extremely demanding transmitter noise floor requirements.SignalbandGuardbandAdjacentsignal bandTransmitter noise floorFrequencyFigure 6-5: Illustration on the guard band definitionAPTable 6-8: Estimates for the guard bands based on transmitter noise floor requirementsLimiting Transmitter Guard band requirementinterference noise floor relative to the bandwidthGuard band requirementscenario NB WB NB WBAP-to-MTAP-to-AP 9 -100 dBm/Hz 2.02 1.54 21.0 MHz 128 MHzRS RS-to-MT -105 dBm/Hz 1.75 1.28 18.2 MHz 107 MHzMT-to-AP -108 dBm/Hz 1.70 1.23 17.7 MHz 102 MHzMTMT-to-RS -113 dBm/Hz 1.96 1.49 20.4 MHz 124 MHzMT-to-MT (a) -128 dBm/Hz 2.75 2.28 28.6 MHz 190 MHzMT-to-MT (b) -123 dBm/Hz 2.49 2.02 25.9 MHz 168 MHz6.2.4 Guard bands based on relaxed requirementsGuard bands based on relaxed requirements are considered in this section in order to avoid too exclusiveconclusions indicated by the previous section based on strict requirements and worst case scenarios.9 Co-location of AP’s is excluded and restrictive 50 m separation between AP’s is assumed.Page 109 (121)

WINNER D2.5 v1.0Firstly, it should be noted that the assumed spectrum masks have relaxed ACPR values, which in turnincrease adjacent channel interference (ACI). The relaxations on ACPR are unavoidable due to technicallimitations foreseen on RF structures.In the following, similar relaxation is applied for coexistence interference. In other words, an increase incoexistence induced interference is allowed to obtain relaxed requirements for the guard bands as well asfor the MT transmitter noise floor. Relaxation is allowed for non-stationary interference and stationaryinterference affecting relay station, whereas no relaxation is allowed to stationary interference affectingaccess point. The impact of relaxed coexistence requirements on system performance can be expected tobe less significant than the one of relaxed ACPR requirements. In other words, the following relaxation ofcoexistence requirements can be assumed to be reasonable and feasible after the unavoidable relaxation ofACPR requirements.Worst case ACI induced by one adjacent channel with the same duplex scheme was calculated for the AP,RS and MT by using the MT-to-AP, RS-to-AP, AP-to-RS, MT-to-RS, RS-to-MR and AP-to-MTinterference examples, respectively. They are obtained as a product of transmission power, ACPR andMCL, and the largest ACI values are tabulated in Table 6-9. However, a lower ACI value caused by MTto-RSinterference was assumed for RS, since AP-to-RS link (resulting in the larger ACI) may havecharacteristics, e.g., beam forming, that reduce ACI in practice.The relaxed guard band requirements were calculated so that the coexistence interference, integrated overthe bandwidth of victim receiver, remains below the worst case ACI values with certain margins.Different margins were set to the carrier on the edge of a spectrum block, interfered by one adjacentchannel, and to other channels interfered by two adjacent channels. The relaxed limits for coexistenceinterference are presented in Table 6-9 and the approach illustrated in Figure 6-6.Table 6-9: Relaxed limits for coexistence interferenceWorst case ACILimits for coexistence interferenceChannel on the edge of bandOther channelsAP -80.9 dBm -89.9 dBm (9 dB margin) -95.9 dBm (15 dB margin)RS -76 dBm -85 dBm (9 dB margin) - 91 dBm (15 dB margin)MT -66.9 dBm -72.9 dBm (6 dB margin) - 78.9 dBm (12 dB margin)Page 110 (121)

WINNER D2.5 v1.0Figure 6-6: Illustration on the definition of relaxed guard bands for MTIt should be also noted that with the relaxed requirements, transmitter noise floor of -113 dBm/Hz issufficient to fulfill the MT-to-MT (a) and (b) interference examples in the case of NB victim receiver.However, in the case of WB victim receiver, transmitter noise floor of -113 dBm/Hz satisfies only theMT-to-MT (b) interference example with 8 dB margin (instead of the required 12 dB margin). Despite ofthis, MT transmitter noise floor of -113 dBm/Hz, set by MT-to-RS interference, is assumed in thefollowing. However, one should note that this requirement is already very tight and should be relaxed ifpossible. The relaxed guard band estimates are presented in Table 6-10.Table 6-10: Estimates for the guard bands based on relaxed requirementsInterferencescenarioCorresponding bandwidth combinationNB-to-NB NB-to-WB WB-to-NB WB-to-WBMT-to-AP 8.4 MHz 57 MHz 58 MHzAP-to-MTNot5.8 MHz 42 MHz 45 MHzMT-to-RS dominating 7.5 MHz 55 MHz 58 MHzAP-to-RS 8.8 MHz 64 MHz 67 MHzRS-to-AP14 MHz 68 MHz 68 MHzAP-to-AP 21 MHz 21 MHz 128 MHz 128 MHzRS-to-RS 5.8 MHz 9.1 MHz 44 MHz 47 MHzMT-to-MT 12 MHz 21 MHz 96 MHz 124 MHz6.3 Comparison of coexistence scenariosIn this section, coexistences of different duplex concepts on the same geographical region are comparedbased on the coexistence scenarios and relaxed guard band estimates presented in previous sections. Theguard band estimates in Table 6-10 are combined with the coexistence scenarios via the interference typespresented in Table 6-2. The obtained indicative guard band estimates are presented in Table 6-11 - Table6-16 for different duplex concept and bandwidth combinations. In the tables, the limiting interferencetype is indicated for each guard band. The guard bands are presented also with and without employmentof relay stations under assumptions that RS transmits towards MT at the same band as AP and towardsAP at the same band as MT.Table 6-11: Guard band estimates for pure FDD / half duplex FDD coexistenceBandwidth combinationFDD / half duplex FDDGuard band 1 Guard band 2 Guard band 3NB / WB57 MHz (MT-to-AP) or68 MHz (RS-to-AP)128 MHz (AP-to-AP)42 MHz (AP-to-MT) or64 MHz (AP-to-RS)WB / NB57 MHz (MT-to-AP) or68 MHz (RS-to-AP)96 MHz (MT-to-MT)42 MHz (AP-to-MT) or64 MHz (AP-to-RS)WB / WB58 MHz (MT-to-AP) or68 MHz (RS-to-AP)128 MHz (AP-to-AP)45 MHz (AP-to-MT) or67 MHz (AP-to-RS)Table 6-12: Guard band estimates for half duplex FDD / pure TDD (and pure FDD / pure TDD)coexistenceBandwidth combinationHalf duplex FDD / TDDGuard band 1 Guard band 2 Guard band 3Page 111 (121)

WINNER D2.5 v1.0NB / WB 128 MHz (AP-to-AP) 96 MHz (MT-to-MT)WB / NB 96 MHz (MT-to-MT) 128 MHz (AP-to-AP)Not neededWB / WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Table 6-13: Guard band estimates for half duplex FDD / DL oriented hybrid (and pure FDD / DLoriented hybrid) coexistenceBandwidth combinationHalf duplex FDD /DL hybridGuard band 1 Guard band 2 Guard band 3NB / WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)42 MHz (AP-to-MT) or64 MHz (AP-to-RS)WB / NB 96 MHz (MT-to-MT) 128 MHz (AP-to-AP)WB / WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)42 MHz (AP-to-MT) or64 MHz (AP-to-RS)45 MHz (AP-to-MT) or67 MHz (AP-to-RS)Table 6-14: Guard band estimates for half duplex FDD / dual band TDD hybrid (and pure FDD /dual band TDD hybrid) coexistenceHalf duplex FDDbandwidthArrangement A:NBWBArrangement B:NBGuard band 1 Guard band 2 Guard band 321 MHz (AP-to-AP)96 MHz (MT-to-MT)57 MHz (MT-to-AP) 10or68 MHz (RS-to-AP)57 MHz (MT-to-AP) 10or68 MHz (RS-to-AP)96 MHz (MT-to-MT)128 MHz (AP-to-AP)21 MHz (AP-to-AP) 128 MHz (AP-to-AP) 96 MHz (MT-to-MT)WB 96 MHz (MT-to-MT) 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Arrangement C:NB21 MHz (AP-to-AP) 21 MHz (AP-to-AP) 96 MHz (MT-to-MT)WB 96 MHz (MT-to-MT) 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Table 6-15: Guard band estimates for pure TDD / DL oriented hybrid coexistenceBandwidth combinationTDD / DL hybridGuard band 1 Guard band 2 Guard band 3NB / WB 128 MHz (AP-to-AP) 96 MHz (MT-to-MT)Not neededWB / NB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)10 Guard band is defined based on coexistence interference assumptions. If interference is interpreted as ACI since itis in the dual band TDD concept, guard band is reduced. NB and WB carriers in the dual band TDD are assumed tobe synchronised.Page 112 (121)

WINNER D2.5 v1.0WB / WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Table 6-16: Guard band estimates for DL oriented hybrid / dual band TDD hybrid coexistenceDL hybrid bandwidth Guard band 1 Guard band 2 Guard band 3Arrangement A:NBWBArrangement B:NB21 MHz (AP-to-AP)128 MHz (AP-to-AP)57 MHz (MT-to-AP) 10 or68 MHz (RS-to-AP)57 MHz (MT-to-AP) 10 or68 MHz (RS-to-AP)96 MHz (MT-to-MT)128 MHz (AP-to-AP)21 MHz (AP-to-AP) 128 MHz (AP-to-AP) 96 MHz (MT-to-MT)WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Arrangement C:NB21 MHz (AP-to-AP) 21 MHz (AP-to-AP) 96 MHz (MT-to-MT)WB 128 MHz (AP-to-AP) 128 MHz (AP-to-AP) 128 MHz (AP-to-AP)Most interesting scenarios can be considered to be the combinations of a duplex concept that does notrequire carrier synchronization, i.e., half duplex and pure FDD, and a duplex concept that exhibits thebenefits of TDD, i.e., pure TDD, DL oriented hybrid and dual band TDD. From such combinations,coexistence of downlink oriented hybrid and half duplex (or pure) FDD concepts has higher guard bandrequirement than other scenarios. The guard band requirements of other such scenarios are also very highand need to be carefully considered.It can be also seen advantageous that the other duplex concept supports narrow band and the other wideband modes. Coexistence of two wideband modes would result in larger guard bands. The limitinginterference scenario would also be AP-to-AP interference in all guard bands, which reduces thepossibilities for further guard band reductions. In the combinations of NB and WB modes, one of theguard bands is limited by MT-to-MT interference and, thus, is more suitable for further guard bandreductions.To illustrate the impact of coexistence on the guard bands, the portion of the required guard bands fromthe total system bandwidth is presented against the total system bandwidth in Figure 6-7. In the figure,combinations of NB half duplex FDD and WB pure TDD, and NB half duplex FDD and WB dual bandTDD with spectrum arrangements A and C are considered. It is also assumed that the guard bands withinduplex concepts compose roughly 19% from the total bandwidth, according to the example systemparameters in Section 5.3.1.Although the combinations of half duplex FDD with dual band TDD appear to have the smallest guardband requirements in relative terms, one should note the constrains of the spectrum arrangements A andC. Synchronization between NB and WB TDD carriers is assumed in the arrangement A, while in thearrangement C, NB TDD carriers are placed between half duplex FDD carriers, which most likely resultsin too narrow duplex distance for half duplex FDD.One should also note that the WINNER system guard bands towards other radio services are not takeninto account in this study. Nevertheless, one can assume that WB mode requires larger guard bandstowards other radio services than NB mode. In the NB-WB coexistence scenarios, there are either one(NB (T+F)DD & DB TDD) or two NB modes (NB (T+F)DD & WB TDD) on the edges of WINNERsystem band. When this is taken into account, the difference between the NB (T+F)DD & DB TDD andNB (T+F)DD & WB TDD combinations is decreased, and the overall price paid in guard bands for thecoexistence of duplex concepts is reduced. Coexistence scenarios with wideband (T+F)DD naturally donot benefit from this.Page 113 (121)

WINNER D2.5 v1.0Figure 6-7: Guard band portion from total system bandwidth as function of total system bandwidth6.4 ConclusionsCoexistence of multiple duplex concepts in the same geographical area was considered in this sectionmainly from the viewpoint of additional required guard bands defined by worst case scenarios andtransmitter characteristics. To facilitate coexistence, limitations like exclusion of co-located access pointsand relay stations were introduced, and an increase on coexistence induced worst case interference wasallowed. With the relaxations, more reasonable transmitter noise floor and guard band requirements wereachieved. The results showed that coexistence of half duplex FDD with TDD or dual band TDD requiresless guard bandwidth than coexistence of half duplex FDD with DL oriented hybrid. The results alsoindicated that it would be preferable with respect to guard bands if half duplex FDD uses narrowerbandwidth than the other duplex scheme.Despite of the relaxations, coexistence of duplex concepts will require large guard bands, thus, havingsignificant impact on the overall efficiency of the system, especially with relatively ‘small’ systembandwidths. In other words, the needs for coexistence clear and coexistence must be seen to providesignificant advantages to justify overhead that will be substantial. Equally, the feasibility and impact ofcoexistence must be thoroughly studied with stochastic simulations. Also all possibilities to reduce guardbands, including further relaxations on AP-to-AP and MT-to-MT worst case interference limits, must beconsidered.Page 114 (121)

WINNER D2.5 v1.07. Network deployment considerations7.1 Synchronization of same carrier APs within one networkAccording to [WIND71] the Winner air interface should not require inter-site synchronization‘everywhere’, but the possibility is left open for scenarios where it is considered ‘acceptable’. In thissection some consequences are briefly discussed.Synchronization of APs in FDD or Half duplex based networks can be beneficial in order to facilitateplanning frequency hopping sequences, location of neighbouring cells etc but the greatest benefit ofsynchronization is for the TDD based systems.Although, it is not required that Winner equipment is synchronised, in TDD systems it is generally a bigadvantage if the network is run in a synchronised and coordinated manner in order to avoid AP-AP andMT-MT interference. That is, that neighbouring cells do not have conflicting views on what is UL andDL.Such operation will have a higher capacity and lower complexity equipment than if the system is run inan uncoordinated manner. However, this will induce a cost for the operator.In order to accomplish this, some sort of synchronization mechanism between APs is needed, and alsosome form of centralised (or at least coordinated within radio range) resource allocation supervision.One way of accomplishing synchronization is by using e.g. GPS in order to establish a time reference.This method is naturally less attractive for indoor APs. Another way is to have an over-the-airsynchronization to synchronise parts of the network which of course costs some radio capacity.7.2 Synchronization between networks on different carriersPreferably, it should not be necessary for operators operating at adjacent carriers to synchronise orcoordinate their deployment or operation. In fact, it is generally not possible since they do not want toshare their business secrets, due to limitations in current legislation.The goal must be that operators in adjacent bands must be able to deploy and operate independently ofeach other with a minimum of coupling, expensive special solutions or site engineering.From this point of view, it seems that FDD and Half Duplex FDD are more flexible since the couplingbetween operators is significantly less problematic when uplink and downlink carriers are separated. TheTDD systems will need sufficient guard band, filter specification, and interference management in theequipment to guarantee the same degree of independence between operators. . Although indicativelyaddressed in Section 5.3.5.1, this requires, e.g., system simulations and is for further study.However, when relaying is introduced the picture is not that simple. Since generally lower powers can beexpected, the interference should also be smaller. It might be that this will alleviate some of the problemsassociated with a higher power TDD based system. This is for further study.7.3 Co-location of APsWhenever a terminal is relatively far from its serving AP and thus transmitting with high power butrelatively close to an adjacent carrier AP, near-far problems might occur, that is that the terminal caninterfere strongly with the adjacent uplink. It is also likely that the adjacent carrier AP will interfere withthe downlink.One way to deal with this for the benefit of both systems is to co-locate APs, since in that way near-farproblem disappears since both APs are either both near or both far away. Another reason for co-location,most likely growing in importance, is environmental demands of as few masts as possible.This solution is possible for FDD, Hybrid FDD or coordinated TDD systems, but not in general foruncoordinated TDD systems. The reasons for this is the extreme and unrealistic filter requirements forsuppression of AP-AP interference since there is now virtually no distance between the antennas.Thus, from a co-location point of view, uncoordinated TDD is out of the question.Page 115 (121)

WINNER D2.5 v1.08. ConclusionsThe analysis on the topic “Duplex Arrangements” carried out within the WINNER project and presentedin the previous chapters enable some conclusions to be drawn on main advantages and drawbacks of theconsidered duplex schemes and, as a consequence, on their suitability in different deployment scenarios.In Section 8.1, major pros and cons of each of the identified duplex arrangements are briefly summarised.Section 8.2 provides then an indication on the most promising duplex mode for each of the deploymentscenarios in which according to [WINIR21] the WINNER air interface should operate.8.1 Pros and cons of considered duplex arrangementsThe observations of Chapter 2 and the complexity study of Chapter 5 allow us to conclude that Pure FDD,commonly referred to also as Full Duplex FDD, is not a good option at the MT. This is due not only tothe need of a good duplex filter in case the frequency duplex distance does not guarantee sufficientdecoupling between transmitter and receiver, but also to the considerable power consumption. Both thesedrawbacks do not prevent an AP to operate in Pure FDD mode, since high complexity and powerconsumptions are assumed to be more affordable than at the MT. This might, however, not hold true froma cost perspective at the RSs (relay station), so yielding some constraints in the choice of the duplex modein case of multi-hop applications, especially in case of mobile RS. The latter topic has been discussed indetail in Section 3.4.The presence of a TDD component, e.g. in Pure TDD, Dual Band TDD and hybrid UL/DL orientedHybrid FDD/TDD (cf. Chapter 2), is in general highly desirable for efficient handling of asymmetrictraffic requirements. Moreover, TDD has an advantage in multihop applications and is definitelypreferable in case of direct link, i.e. terminal-to-terminal communications, as discussed in Chapter 3.Furthermore, the exploitation of channel reciprocity using TDD may bring considerable benefits for thoselink adaptation and spatial processing schemes relying on short-term channel state information (CSI) atthe transmitter, especially in short range scenarios. Despite the many advantages, TDD exhibits one majordrawback represented by the possible co-channel or adjacent channel interference (AP-to-AP and MT-to-MT) arising in case of unsynchronised and/or uncoordinated operators not properly spatially and/orgeographically decoupled. This issue has been extensively discussed in Chapter 4, where an interferenceavoidance method has been proposed, which can alleviate the problem, but can not work in case of colocationof APs. The stringent RF requirements and the guard bands between carriers in case ofunsynchronised/un-coordinated TDD operation have been derived in Chapter 5. Another drawback ofTDD may be given by the intrinsic delays in feedback signalling, e.g. each MT has to wait the whole DLphase of the frame before transmitting. A suitable frame structure balancing between guard time overheadat the switching points and feedback delays may, however, solve the problem.Half Duplex FDD does not suffer crosslink interference as TDD, while avoiding the self-interference(between transmitter and receiver at one terminal), and hence the complexity, of Full Duplex FDD at theMT. Half Duplex FDD may have an advantage with respect to TDD regarding delays in feedbacksignalling, since it is not necessary for a single MT to wait the whole DL phase of the frame to transmit, itis only necessary that a MT transmits and receives in non overlapping time slots. On the other hand, HalfDuplex FDD, as well as Pure FDD, exhibits the drawback of relying on paired bands, one for the UL andone for the DL with a sufficient duplex distance. This could represent an issue if high data rates, up to 1Gbps, and hence large transmission bandwidths, up to 100 MHz, are required in some scenarios, asaccording to the requirements for the WINNER air interface formulated in [WIND71].The DL/UL Hybrid FDD/TDD solution, given no simultaneous transmission and reception (i.e. avoidanceof Full Duplex FDD) at the MT, is not promising in that some advantages of the hybrid solution, e.g. thepossibility of continuous feedback signalling, are excluded. Moreover, by allowing both transmission andreception on one band, interference situations as in TDD may arise.Dual Band TDD is a variant of TDD, whereby both a narrowband and a wideband are foreseen. Thebenefits of this arrangement have been explained in Section 2.5. This variant exhibits the sameinterference issue as TDD. Hence, its application will be limited in the same scenarios as TDD.Band switching FDD is not envisaged to be a promising solution. The beneficial of channel reciprocityenabled by this scheme seems not to compensate the increased complexity.Page 116 (121)

WINNER D2.5 v1.0The feasibility of coexistence of multiple duplex schemes has been analysed in Chapter 6 in terms ofadditional required guard bands between spectrum portions assigned to different duplex modes, byassuming some exemplary spectral arrangements and transmitter requirements. It has been estimated thatthe coexistence of Half Duplex FDD with TDD or Dual Band TDD requires less guard bandwidth thanthe coexistence of Half Duplex FDD with DL oriented Hybrid. Guard band requirements are likely alsomore reasonable if the half duplex FDD uses narrower bandwidth than the other duplex scheme.8.2 Duplex arrangements for the envisaged deployment scenariosWith reference to the deployment scenarios characterised in [WINIR21], a suggestion for the mostpromising duplex arrangement for each scenario is given in this section.The main deployment scenarios are distinguished as short range and wide area. In the short rangescenario, we can distinguish conventional cellular networks, base station to relay connections andterminal to terminal communications. Similarly, for the wide area, both conventional cellular networksand base station to relay connections are envisaged.8.2.1 Short range cellular networksIn short range cellular networks, where the cell range is envisaged to be on the order of 10 m to 100 m,Pure TDD is the most promising candidate duplex scheme 11 .In indoor office applications, only one operator is likely present. In indoor hot spot scenarios, e.g.exhibitions and airports, a proper positioning of the APs and the typically low transmit power reduces theissue of crosslink interference, so that co-ordination between APs is not a requirement.In outdoor, synchronization and co-ordination between different operators becomes necessary, if thesystem is TDD based, unless spatial decoupling and/or interference avoidance techniques can guaranteesufficiently low levels of crosslink interference. In short range cellular networks, frame synchronizationbetween operators can be quite easily achieved as discussed in [WIND21]. The need for co-ordinationand the consequent reduction of service flexibility and independence may be acceptable for operators inscenarios in which high data rates, up to 1 Gbps, are expected as according to [WINIR21], when themaximum bandwidth of 100 MHz is available. There may be a spectrum issue to accommodate so widepaired bands. TDD has an advantage in this respect since it relies only on one unpaired band. Moreover, ithas to be considered that co-ordination of the switching points might be acceptable for close or co-locatedoperators, whose traffic characteristics, i.e. asymmetry factors, are likely similar. If the co-ordinationeffort is not acceptable for the operators, the Half Duplex FDD is the most promising alternative (cf.Section 8.2.3), although a certain reduction in achievable data rates may have to be accepted due to thelimited availability of wideband paired spectrum.8.2.2 Short range terminal to terminalIn short range terminal to terminal applications, Pure TDD is definitely the most advantageous. Whenevertransmission and reception occur on two separate bandwidths, if every terminal should be capable oftalking with any other terminal, some terminal is forced to operate in band switching mode, withconsequences on interference level and hardware complexity.8.2.3 Wide area cellular networksIn wide area cellular deployment scenarios, for which cell range up to 2 Km is foreseen [WINIR21], HalfDuplex FDD is the most promising candidate. As recalled in Section 8.1, the crosslink interference issuestypical of TDD mode and the self interference of Pure FDD are avoided. No synchronization and coordinationis required between operators, thus allowing them an independent and flexible usage of theallocated resources. In comparison to TDD, Half Duplex FDD has the main drawback of requiring pairedbands. This may imply limitations on the available bandwidth and hence supported data rates in wide areascenarios, if the system operation relies only on this duplex mode. Another drawback is that no channelreciprocity can be exploited. However, it is currently envisaged within the WINNER project that this11 As pointed out in the Section 8.1, Dual Band TDD exhibits the same advantages and drawbacks of PureTDD. Hence, whenever Pure TDD is indicated as most promising duplex mode, Dual Band TDD could beconsidered as well. The choice between Pure TDD and Dual Band TDD will be dictated by other factors,such as required coverage and availability of spectrum.Page 117 (121)

WINNER D2.5 v1.0feature is crucial for link adaptation and spatial processing schemes relying on only short term CSI at thetransmitter. Long term information can be extracted as well from FDD modes.8.2.4 Access Point to Relay StationFor Access Point to Relay Station connections, both in wide area and short range scenarios, the choicebetween Pure TDD or Half Duplex FDD mode of operation mainly depends on the complexity affordableat the RS. If the RS is meant to be also MT, then the duplex arrangement not only between usual uplink(MT to AP) and downlink (MT to AP) but also of the different hops involving the RS has to be designedin such a ways to avoid Pure FDD, dual transceiver chains and/or Band Switching FDD at the RS. All thiscan only be accomplished with pure TDD. For fixed RS, where a higher complexity is acceptable, alsoHalf Duplex FDD is an option.8.3 Suggestion for the Way ForwardIt has to be remarked that due to the limited resources planned for this study within the WINNER Project,the conclusions and the suggestions derived above are based mainly on qualitative considerations and onquantitative investigations carried out under assumptions which are sometimes too pessimistic and depicta worst case scenario rather than an average scenario. Further investigations based also on dynamicsystem level simulations, e.g. properly modelling traffic and user distribution statistics, would be requiredin order to validate the proposed duplex schemes. Moreover, the suitability of a duplex scheme to a givenscenario is not the only aspect to be taken into account in the choice of the most promising duplexarrangement. Besides that, spectrum availability plays a crucial role. The WINNER air interface isassumed to support broadband communications. As discussed in Chapter 6, the feasibility of thecoexistence of different duplex modes in one air interface or in different systems, which operate inadjacent bands, should be assessed by means of more extensive simulative analyses. Moreover, in thisstudy, interference issues related to spectrum sharing by different operators utilizing the same band havenot been addressed. For these purposes, more insight into the availability of spectrum resources would benecessary, in order to base the investigations on realistic assumptions.More specifically, in order to get more complete view of relevant issues, we propose a list of studieswhich could (and probably should) be addressed within the WINNER Project:• More exact coexistence and interference studies by taking into account the actual choices inWINNER of e.g. system bandwidths, transmission technology, and multiple access schemes.• Evaluation also by means of system level simulations using ‘realistic’ user density models of thepotential of interference management based on a clever resource allocation (theoretical analysispresented in Chapter 4) and signal processing (e.g. spatial processing).• Study also by means of system level simulations using ‘realistic’ user density models and suitableinterference management methods of the interference situations arising in case ofo Coexistence of multiple duplex modes (based on deterministic calculations in Chapter 6);o Spectrum sharing;o Multi-hop communications and ad-hoc networks.• Evaluation of trade-off between pros and cons of coordination between TDD based AP/RSsbelonging to different systems.• Development of mechanisms for synchronization (started in [WIND21]) and co-ordination betweenoperators on adjacent carriers and between cells in one system in case of TDD operation.• Quantification of the potential of channel reciprocity in TDD based systems.• Evaluation of the cost/feasibility from MT, network and spectrum availability point of view, of atwo-mode duplex scheme, comprising both the currently most promising candidates.Page 118 (121)

WINNER D2.5 v1.0References[3GPPWCDMA][AA04][Adhoc][AHM-00a][AHM-00b][GSM]3GPP TS 21.101v5.7.0 Technical Specification and Technical Report for a UTRANbased 3GPP SystemAnegeliki Alexiou, Duplexing, Resource Allocation and Inter-cell CoordinationDesign Recommandations for next Generation Systems, WWRF/WG4 White Paper,version 0.1J. Habetha, S. Mangold, J. Wiegert, 802.11a versus HiperLAN/2 - A Comparison ofDecentralized and Centralized MAC Protocols for Multihop Ad-Hoc RadioNetworks.Mohamed Ahmed, Samy Mahmoud, Capacity Analysis of GSM Systems UsingSlow Frequency Hopping and Smart Antennas, Proc. VTC2000, Tokyo, Japan, May2000.Mohamed Ahmed, Wei Wang, Samy Mahmoud, Downlink Capacity Enhancementin GSM Systems with Frequency Hopping and Multiple Beam Smart Antennas, ICC2000 - IEEE International Conference on Communications, no. 1, pp. 1015-1019, June 2000.European digital cellular telecommunications system (Phase 2);General descriptionof a GSM Public Land Mobile Network (PLMN) (GSM 01.02)[IEEE802.11] ANSI/IEEE Std 802.11. Part 11: Wireless LAN Media Access Control (MAC) andPhysical Layer (PHY) specifications.[IEEE802.16] ANSI/IEEE Std 802.16. Part 16: Air Interface for fixed Broadcast Wireless AccessSystem[JEO-00] Wha Sook Jeon, Dong Geun Jeong, Comparison of Time Slot Allocation Strategiesfor CDMA/TDD Systems, IEE Journal on Selected Areas in Communications, Vol.18, No.7, July 2000[HAA-01] Harald Haas, Stephen McLaughlin, A Dynamic Channel Assignment Algorithm fora Hybrid TDMA/CDMA-TDD Interface Using the Novel TS-Opposing Technique,IEEE Journal on Selected Areas in Communications No. 10, pp. 1831-1846, October2001.[HUL-04] A P Hulbert, Spectrum Sharing through Beacons, not yet submitted for publication,2004.[HypAcc] ETSI TR 102 2003: HA System Overview.[MacSurvey] Survey&Tutuorial Wireless Medium Access Control Protocol, IEEECommunications, Survey&Tutorials.[PAR-02] A. Parssinen. Direct Conversion Receivers in Wideband Systems, KluwerInternational Series in Engineering and Computer Science, 2002.[RAZ-98] B. Razavi. RF Mictoelectronics, Prentice-Hall, 1998.[RIN-04] M. Rinne, P. Pasanen, P. Seppinen, K. Leppänen. Dual Bandwidth Approach to NewAir Interface, paper in WWRF#11 WG4, 10-11.6. 2004, Oslo.[SCH-03] M Schacht, A Dekorsy, P Jung, System Capacity from UMTS Smart AntennaConcepts, IEEE Vehicular Technology Conference (VTC 2003-Fall), Oct 2003[TOR-04] Hideyuki Torii, Makoto Nakamura, Naoki Suehiro, A New Class of Zero-Correlation Zone Sequences, IEEE Trans. On Information Theory, Vol. 50, No. 3,March 2004[TöCo]A Tölli, M Codreanu, Compensation of interference non-reciprocity in adaptiveTDD MIMO-ODFM system, Proc. PIMRC, Barcelona, Spain, Sep. 2004.[WIND21] Winner Deliverable D21. Identification of Radio Link Technologies.[WIND71] Winner Deliverable D7.1 System Requirements.[WINIR21] Winner Internal Report IR2.1Initial AssumptionsPage 119 (121)

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