Evolutionary Comparison of LTE over WiMAX - IRD India

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International Journal on Advanced Computer Theory and Engineering (IJACTE)Since WiMAX is envisioned to provide end-to-endIP services and will likely be deployed using an IP corenetwork, IP QoS and its interaction with the wirelesslink layer are what is most relevant to WiMAX networkperformance. The QoS provided by a network is aperformance level indicator, typically specified in termsof throughput, packet loss, delay, and jitter, and therequirements vary, based on the application and service.There are more components and functionalities in anend-to-end network providing QoS than the air interfaceQoS features discussed above, such as policy controland charging (PCC) functions in QoS provisioning.―Fig.3‖ shows the general flow of QoS in LTE. Weshow the comparison of the QoS framework betweenLTE and IEEE 802.16e/IEEE 802.16m at the airinterface [6]:• QoS transport unit: The basic QoS transport unit inthe IEEE 802.16e/IEEE 802.16m system is an SF, whichis a unidirectional flow of packets either UL from theMS/AMS or DL packets from the BS/ABS [7]. Thebasic QoS transport in LTE is a bearer between UE andthe PDNGW. All packets mapped to the same bearerreceive the same treatment.• QoS scheduling types: There are six schedulingservice types in IEEE 802.16m including UGS, ertPS,rtPS, nrtPS, and BE from IEEE 802.16e and the newlydefined aGP service. LTE supports GBR and non-GBRbearers. The GBR bearer will be provided by thenetwork with a guaranteed service rate, and itsmechanism is like rtPS; the non-GBR has no suchrequirement and performs like BE in IEEE802.16e/IEEE 802.16m [7].• QoS parameters per transport unit: Depending onthe SF type, IEEE 802.16e/ IEEE 802.16m can controlmaximum packet delay and jitter, maximum sustainedtraffic rate (MSTR), minimum reserved traffic rate(MRTR), and traffic priority. LTE MBR and GBR aresimilar to IEEE 802.16e/IEEE 802.16m MSTR andMRTR, respectively. However, MBR and GBR are onlyattributes of GBR bearers, while in IEEE 802.16e/IEEE802.16m even a BE SF can be rate limited using itsMSTR. Also, with 3GPP Release 8, GBR and MBR areset equal, while IEEE 802.16e/IEEE 802.16m allows theoperator to select independent values for MSTR andMRTR. On the other hand, LTE AMBR allows theoperator to rate cap the total non-GBR bearers of asubscriber [7].• QoS handling in the control plane: The SF QoSparameters are signaled in IEEE 802.16e/IEEE 802.16mvia DSx/AAI-DSx messages. In LTE the QCI andassociated nine standardized characteristics are notsignaled on any interface. Network initiated or clientinitiated QoS are both supported in IEEE 802.16e/IEEE802.16m systems. Therefore, both operator managedservice and unmanaged service can be supported. Theflexible architecture gives the mobile clientopportunities for differentiation. LTE only supportsnetwork initiated QoS control [7].• QoS user plane treatment: The ARP parameter inLTE provides the following flexibilities to the operator:–Accept or reject establishment or modification ofbearers during the call admission control decision basedon not only the requested bandwidth, availablebandwidth, or number of established bearers, but alsothe priority of the bearer –Selectively tear down bearersbased on their priorities during an overload situation [7].Fig.3: General Flow of QoS in LTEIII. LTE VS WIMAXThe primary difference between LTE and WiMAXare the differences in upbringing: like close cousins,there are deep blood ties between the two standards,(similar frameworks of technology), but the ‗families‘that have raised them are different: different goals anddifferent means. But as each group has now preparedtheir standards to fulfill proposal requirements mandatedby ITU, International Telecommunications Union, IMT-Advanced, the two standards are seeking jobs at thesame huge ‗factory‘ – the factory of open IP unifiedcommunications [8].So, when the discussion is about ‗What is WiMAX(or LTE)‘ the answer should also include a statementthat ―these are two systems developing along the samelines but optimized to work somewhat differently.WiMAX is primarily aimed at Greenfield (new) fixed tomobile deployments while LTE is mostly aimed atincumbent (existing) deployments that must work withexisting networks and business practices‖ as shown in―Fig.4‖ [9].But you can quickly see even that is a simplificationthat does not completely fit the current state ofdevelopment: Sprint now sells dongles with mobiledevices soon to appear that will support both Clearwire‘s WiMAX and Sprint‘s 3G EVDO [10] – [11]. Andthey are working on doing seamless hand-offs of voice14ISSN (Print) : 2319 – 2526, Volume-2, Issue-4, 2013
International Journal on Advanced Computer Theory and Engineering (IJACTE)and other communications. That will soon mean users ofGoogle Android or other phones and mobile deviceswill be able to start a VoIP call on the WiMAX networkand keep on talking as they travel to a Sprint orcollaborating 3G network. Chips are in the works to alsoallow that to happen across WiMAX and HSPA/GSM.Likewise, some LTE developers say it will be used forfixed networks as well as for mobile networks.Fig.4: Potential Deployment of WiMax & LTEThe next versions of both, 802.16m WiMAXm andLTE-Advanced [12], are being designed to meet thesame guidelines for IMT-Advanced which calls for anadaptive framework that can be used from local areafixed networks to large scale mobile networks and to usemultiple carriers across multiple bands of spectrum.―Fig.5‖ shows that, how latency in decreased andcapacity in increased over the year for LTE.Fig.5: Performance of LTE Over the YearThe 4G LTE network is only available in 38 citiesin the USA, covering about 35% of the current Verizonsubscribers. The company is quickly building moretowers across the country, but it will not be nationwideuntil 2013.Carriers can choose to deploy LTE networks eitherin FDD (frequency division duplex) or TDD (timedivision duplex) versions. Since WiMax is a TDtechnology and shares more assets with the latter, TD-LTE presents a more efficient migration option forWiMax operators. Those with broad spectrum rightssuch as Clear wire in the US have the option of dividingup that spectrum between WiMax and TD-LTE so thatthey can enter the LTE market without cutting off theirexisting subscriber base. .There are upcoming spectrum auctions for 2.3 GHzand 2.5 GHz spectrum bands that is better suited forTDD. Operators so far found little interest in the TDDband and WiMax had positioned itself very well for theTDD band. Operators are in general opposed to theWiMax roll out as it encourages open ecosystem andmoreover was an entirely different technology with noevolutionary path from either GSM or CDMA. WiMAXis controlled by IEEE, the consumer electronicsindustry, which is far more open than telecom/3GGP.However, now operators see a clear synergy in rollingout TD-LTE networks if the TDD spectrum comes upfor auction. In India, the operators may actually bebidding for BWA to roll-out TD-LTE rather thanWiMax. [13] – [14].IV. CONCLUSIONMobile WiMAX is superior to LTE in terms ofsecurity aspects in mobile enterprise networks. Also thedeployment speed and the low costs are advantages forMobile WiMAX. In addition, it is more power-efficientin the overall power consumption. Moreover, the currentdeployment and coverage of Mobile WiMAX is muchhigher. However, the LTE deployment recently startedand more and more operators choose the LTE/SAEarchitecture for their future wireless telecommunicationnetwork. The main reason for this is that the majority ofoperators uses 3GPP GSM or UMTS networks andparticipates, within the 3GPP, in the development offuture 3GPP networks [15]. LTE-Advanced andWireless MAN-Advanced provide future extensions tothe current approaches. Therefore both technologies areassured of a good future. The competition scenarios arediverse and depend on the deployment region. LTEdominates the Western European market, whereasMobile WiMAX is the only 4G technology in India. Inconclusion, as in the previous generations oftelecommunication networks there will be a global coexistenceof LTE and Mobile WiMAX and their futuredevelopments. We also presented the mapping of QoSparameters between WiMAX and LTE to provideassured QoS to the end users .As per the comparisonchart it is imperative that both Mobile WiMAX and LTEhave merits over the other and hence both MobileWiMAX and LTE technologies can co-exist with eachother.15ISSN (Print) : 2319 – 2526, Volume-2, Issue-4, 2013
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