A Study On The Performance Of DSTFC And Distributed DSTBC/DSTFC

Differential space time frequency codes(DSTFC) can fully exploit the spatial, temporal and frequency resources which are provided by multiple input multiple output(MIMO)-orthogonal frequency division multiplex(OFDM) system to improve its average bit error rate(BER) performance. The decoding of DSTFC adopts differential detection that without channel state information(CSI). Compared with coherent detection, differential detection will result in3dB performance deterioration, this performance gap can be narrowed through multiple symbol differential detection(MSDD) algorithm, while the decoding complexity of MSDD grows exponentially with the observation window sizes. Sphere decoding can achieve approximate average BER performance with maximum likelihood(ML) algorithm, in order to reduce high complexity of MSDD, multiple symbol differential sphere decoding(MSDSD) algorithm which combines SD algorithm with MSDD algorithm is proposed in this paper.Applying the coding principle of differential space time block codes(DSTBC) as well as DSTFC to cooperative communication system, thus distributed DSTBC and distributed DSTFC are constructed; two way(TW) communication system can improve the spectral efficiency of cooperative system; This paper investigate the decoding algorithm of distributed DSTBC and distributed quasi-orthogonal differential space time block codes(QODSTBC) and construction and error performance of distributed block diagonal DSTFC in TW communication system.Chapter1makes introduction to the research status of coding and decoding algorithm of DSTBC/DSTFC and distributed DSTBC/DSTFC.Chapter2applies MSDSD algorithm to the decoding of differential unitary space time frequency codes(DUSTFC), derives decision metric and gets concrete flow diagram for MSDSD algorithm. Simulation results show that MSDSD algorithm can improve the error performance of DUSTFC with low decoding complexity.Chapter3investigates the decoding algorithm of distributed DSTBC, proposes M algorithm with low decoding complexity which based on MSDD for two-relay distributed DSTBC. Upper bound of average BER expression is derived with M-ary differential phase shift keying(DPSK) modulation for two-relay distributed DSTBC over Nakagami fading channels. Theoretical and simulation results show that the error performance of distributed DSTBC with M algorithm can be improved through increasing the channel fading parameters or extending the observation window sizes; upper bound of average BER results and simulation results are approximate accordance for two-relay distributed DSTBC Chapter4investigates the construction and error performance of distributed block diagonal DSTFC in TW communication system. Simulation results show that the error performance of block diagonal DSTFC can achieve better performance compared with DUSTFC under condition of the same data rate; time domain DSTFC can achieve better performance than frequency domain DSTFC.Chapter5finishes this paper with concluding remarks.