Application Of MIMO Iterative Detection Based On FP-MAP Algorithm In LDPC-coded Cooperative Communications

In conventional wireless communication system, the transmitting end and the receiving endusually each uses only one antenna, such single-antenna system is referred to single-inputsingle-output system. For such systems, Father of Information Theory-Shannon gave its channelcapacity formula in1948. Shannon channel capacity is recognized as an insurmountable boundary,becoming a major bottleneck in the development of traditional wireless communication.However, with the extensive use of mobile communications, users propose higher and higherdemands on transmission rate and reliability of wireless communication.Therefore, many relevantresearchers emphasize their study on multi-antenna communication technology, especially onmulti-input multi-output (MIMO) technology, which can not only break through the capacity boundryof traditional wireless communication system but also improve the effiency of spectrum use.Currently, MIMO technology is a research focus in the field of wireless communication. AlhoughMIMO technology can siginificantly improve the channel capacity of a single system, it is difficult toapply MIMO technology to wireless mobile terminal with single antenna directly.In order to solve thisproblem, people introduced the concept of cooperation later so that mobile terminals with singleantenna are able to share mutual antennas, thereby obtaining virtual diversity gain.This thesis studied multi-antenna wireless communication technology first, stressing on spheredetection technology of MIMO system,which can get excellent performance close to the optimaldetection with low computational complexity;Secondly, in order to improve communicationperformance of single-antenna users, let multiple single-antenna users share mutual antennas toimprove the reception performance; Next，in order to operate reception processing on received signalwhen receiver do not know channel state information(CSI), it is necessary to adopt channelestimation;Finally, this thesis studied joint iterative detection and decoing technology and applied it toLDPC-coded cooperative communication system, where this thesis’s innovation lies in.Simulationresults gave bite error rate curves of iterative processing methods under different signal-to-noiseratio(SNR). Those simulation results show that applying this iterative decoding scheme cansiginificantly improve the performance of system, thus proving that this method can indeed improveinformation reception quality.The main research work of this thesis is basically summarized as follows：1. Understand multi-antenna wireless communication technology in-depth, focusing on MIMOtechnology and its corresponding sphere detection method. 2. In single-input single-output communication environment, research encoding and decodingtechnology of LDPC code, and simulate performance of LDPC code by MATLAB language, gettingSNR-BER curves under different circumstances.3. In order to let single antenna users obtain diversity gain, single relay cooperate communicationmodel based on systematic LDPC codes is proposed.Research work is done in additive whiteGaussian noise channel and Rayleigh fading channel for ideal cooperation and non-ideal cooperation,respectively.4. For those communication systems whose channel state information (CSI) is unknown forreceiving end, in order to obtain channel information, channel estimation must be adopted at thereceiving end. This paper’s channel estimation is based on the pilot sequence.5. So as to further improve the performance of receiving, joint iterative detection and decodingtechnology is applied to cooperate communication system with LDPC coding.