Yue Zhang, C.H. Zhang, J. Cosmas, K.K. Loo, T. Owens, R.D. Bari, Y ...

IEEE TRANSACTIONS ON BROADCASTING < 5obtain. In this paper, the CNR is computed based on themaximum CNR the receiver can obtain in the presence of thecontributed and interference signals. Also, it is assumed in thispaper that all the transmitters have the same transmitting powerand all the transmit antennas are omni directional with the sameheight. The first signal to arrive at one receiving location is alsothe strongest one without a terrain model. In this case, themaximum CNR can be obtained when the start time of FFTwindow is aligned with the first signal received. The algorithmused to calculate the coverage radius can be found in [17]. Thenetwork simulation parameters are based on Table IV.with assuming 2-antenna transmitters (2Tx) and 2-antennareceivers (2Rx). For 2Rx with receive diversity, the signals arecombined using MRC. The single-antenna (1Tx/1Rx) system inwhich there is no spatial diversity is simulated for reference.System parameter settingPathloss computationCompute delay timefrom different SFNtransmitterComputeweighting coefficientFig. 3. Performance of CDD DVB-H in uncorrelated TUCompute CNR mean anddeviation using statisticalcombine methodOutage probabilitycomputationResult presentationFig. 2. Flow chart of the coverage simulation for one pixelTABLE IVSIMULATION PARAMETERSParametersValueTransmitter frequency (Mhz) 900Transmitter power (dBW) 10~45Transmitter antenna height (m) 20~300Receiver height (m) 1.5Transmitter antenna pattern OmniSymbol time (μs) 448Guard interval time (μs) 112 (1/4 of symboltime)Receiver noise level (dBW) -129 (with areceiver noisefactor = 6dB)Shadowing deviation (dB) 6CNR threshold (dB) 9.7;11;14; 17Fig. 4. Performance of CDD DVB-H in uncorrelated RAA. Simulation Results for CDDFigures 3, 4 and 5 show the BER performance for the TU,RA and ID radio environments with CDD transmit diversityapplied to the DVB-H system in 4K mode with QPSKmodulation and code rate 1/2. The simulations are carried outFig. 5. Performance of CDD DVB-H in uncorrelated Indoor-BCDD transmit diversity exploits the scattered signalpropagation paths where under these conditions, the channel is

IEEE TRANSACTIONS ON BROADCASTING < 8is improved with increasing diversity gain in CNR. When thediversity gain is 4.5dB, there is about a 20 m saving in thetransmitter height to cover 5000 m for reuse factor 7 in RAchannel. For reuse factor 9, there is about a 10 m saving. Whenthe diversity gain is 7.3dB the transmitter height can be reducedby 100m for reuse factor 7 and by 30 m for reuse factor 9. Thusthe saving in transmitter height depends on the reuse factor ofthe network. For a diversity gain in CNR of 6dB, the transmitterheight saving for reuse factor 9 is 25 m and the transmitterheight saving for reuse factor 7 is 85 mFig. 12 shows the coverage improvement versus diversitygain in CNR for reuse factors 7 and 9 in RA channel. Thetransmitter power is 48dB and the transmitter height is 150 m.From the figure, it can be seen that the network coverage isimproved with increasing diversity gain in CNR. When thediversity gain is 4.5dB, the coverage improvement is about2500 m for reuse factor 7 and about 1000 m for reuse factor 9.When the diversity gain is 7.3dB, the coverage improvement isabout 8000 m for reuse factor 7 and about 5000 m for reusefactor 9. Thus the network coverage improvement depends onthe reuse factor of the network for a given transmitter powerand height.V. CONCLUSIONThis paper has presented an investigation of DVB-H networkcoverage with the application of CDD transmit diversity. Thechannel model and the simulations follow a statistical approachfor the sake of simplicity. The simulation results suggest thatCDD can deliver improvements of about 7.3 dB, 6dB and4.3dB in CNR threshold in RA, Indoor-B and TU environments,respectively, with 2 transmitter antennas and 1 receiver antennacompared with the standard 1Tx/1Rx system and thus assistsDVB-H SFN network planning. In addition, CDD not onlyreduces the network costs in terms of the transmitter power,antenna height and frequency reuse factor, but also improvesthe DVB-H cellular network coverage. There are about 11 dB,16dB and 19dB gains in transmitter power for 5000 m coveragefor reuse factor 7 with transmit antenna height at 150 m forCDD with 2Tx/1Rx DVB-H systems in TU, Indoor-B, and RAchannels, respectively. Furthermore, the gain in transmitterpower is increased by increasing the CDD diversity gain inCNR (C/N). There is a threshold for the gain in transmitterpower in terms of the CDD diversity gain in CNR. Thetransmitter height can be decreased as the diversity gain inCNR increases. For given transmitter height and transmitterpower level, the greater the diversity gains the greater thenetwork coverage improvement. Finally, the gain in transmitterpower is decreased by the increasing the frequency reuse factor.As perspectives to this work, it is envisaged to use otherchannel models including site-specific deterministicpropagation tools to refine the analysis on special cases.Furthermore the impact of the signal correlation is currentlyinvestigated.ACKNOWLEDGEMENTThe work presented in this paper was supported by theEuropean Commission IST project PLUTO [18]. The authorswould like to express special gratitude all the PLUTO projectpartners for their valuable contributions to the research.REFERENCES[1] European Telecommunications Standard Institute ETSI York: DigitalVideo Broadcasting (DVB); DVB-H Implementation Guidelines, Feb.2005. TR 102 377 V1.1.1[2] A. Mattsson, “Single frequency networks in DTV,” IEEE Trans.Broadcasting, vol.51, no.4, pp.413-422, Dec. 2005[3] Wang, J.-T.; Song, J.; Wang, J.; Pan, C.-Y.; Yang, Z.-X.; Yang, L.;, “Ageneral SFN structure with transmit diversity for TDS-OFDM system,”IEEE Trans. Broadcasting, vol.52, no.2, pp.245-251, June. 2006[4] Kornfeld, M.; May, G.;, “DVB-H and IP Datacast—Broadcast toHandheld Devices,” IEEE Trans. Broadcasting, vol.53, no.1, pp.161-170,March. 2007[5] European Telecommunications Standard Institute ETSI York: DigitalVideo Broadcasting (DVB); Framing structure, channel coding andmodulation for digital terrestrial television. Jul. 1999. EN 300 744 V1.2.1.[6] A. Dammann and S. Kaiser, “Standard conformable antenna diversitytechniques for OFDM systems and its application to the DVB-T system,”in IEEE Globecom, pp. 3100–3105, Nov. 2001[7] Y. Zhang, J Cosmas, M. 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