Researches On Key Techniques Of Multi-antenna In Keyhole And Distributed Channels

As a key technology in the next generation of wireless communication systems,STCs (Space-Time Code) have been considered by many researchers, who focus on theconstruction criteria, design method, and performance analysis over different fadingchannels. Among these coding schemes, orthogonal STBC (Space-Time Block Code)attracts many attentions due to its simple decoding complexity and full diversityperformance, and its performance will be studied over a special keyhole channel in thispaper. On the other hand, due to the advantage of capacity, distributed antenna systemsshall also be studied.Chapter 1 first introduces current research scope and development of MIMO(Multiple-Input Multiple-Output) systems, especially the space-time multiplexing andspace-time coding are focused. Next the keyhole fading channels and distributedMIMO systems are shown concisely, and the impact of keyhole on the performance ofSTC systems and the advantage of distributed MIMO systems are also pointed out.Because there are not explicit close-formed solutions for error rate performance oforthogonal STBC systems in Rayleigh keyhole channels, in chapter 2, we analyze theSER/BER (Symbol Error Rate/Bit Error Rate) performance of orthogonal STBC inRayleigh keyhole channels with M-QAM (M-ray Quadrature Amplitude Modulation)and M-PSK (M-ray Phase Shift Keying) modulations. According to the expression ofoutage probability, the diversity gain of such channels is provided. Based on the MGF(Moment Generation Function) method, the exact close-formed SER expressions arederived. Especially, when the number of transmit and receive antennas is different,asymptotic SER expressions are also provided.In chapter 3, the work in chapter 2 is extended to more general canse, i.e., fromRayleigh keyhole channels to Nakagami keyhole channels. Performance analysis oforthogonal STBCs with M-QAM/M-PSK modulations is presented in non-identicallydistributed Nakagami keyhole channels. Through the MGF method, the exact andasymptotic SER expressions are derived.According to the similar analysis methods as shown in chapter 3, the error rate performance of orthogonal STBCs with M-QAM/M-PSK modulations is analyzed overnon-identically distributed Nakagami MIMO channels in chapter 4. It should be notedthat the channels we focus in this chapter are normal MIMO channels, not keyholechannels. Using the MGF method, at high SNRs, the asymptotic SER expressions innon-identically distributed Nakagami MIMO channels are proposed.Different from chapter 2, 3 and 4, wherein space-tme coding is our emphasis,space-time multiplexing is studied in chapter 5. A signal detection method fordistributed antenna systems is presented. According to the system model in the receiver,a sorted Cholesky decomposition algorithm is suggested, which has a betterperformance and a lower complexity than the existing algorithm.We draw a conclusion in chapter 6, and point out possible research directions inthe future.