| The goal of future wireless communications is achieving higher transmission rates and spectrum efficiency with lower latency and power consumption. The fading characteristic of the wireless channel is the main factor degrading the performance of wireless communication systems. While increasing the transmit power can be used to expand coverage to improve the quality of service, however this method not only results the increasement of power consumption and also causes a problem of inter-cell interference. Diversity is an effective method to combat fading. Space diversity technique is a way to achieve diversity gain, which improving the reliability of the transmission without the additional consumption of spectrum and time. However, in some wireless communication systems such as the wireless sensor network and the cellular mobile communication system, due to the cost, bulk etc., it is difficult to apply multiple antennas at the user terminal to obtain significant diversity gain. Therefore, in practice, multiple antennas can only be applyed in the access point or base station.Cooperative diversity techniques by forming a virtual antennas array may be one of the most effective ways to solve this crucial problem. In recent years, scholars did a lot of research for cooperative communication while low density parity check(LDPC) coded cooperation is one of the important topic. By applying LDPC codes to relay cooperation, LDPC-coded cooperation obtains both cooperatve diversity gain and high coding gain. This dissertation intends to focus on some key technologies in LDPC-coded cooperation. Specifically, we mainly investigate the performance and codes design of LDPC-coded cooperation. The main content is as follows:1. The model of coded single and multiple relay cooperation is investigated. After introducing the concepts of ideal and non-ideal coded relay cooperation, the characteristic of multiplicative interference in non-ideal coded cooperation is analyzed.2. LDPC coded cooperation with multiple receive antennas in the destination is proposed, which can achieve cooperative diversity gain, high coding gain and receive mult-antenna gain simultaneously. For this system, a coding schem employing regular LDPC codes is proposed. The equalent check matrix in view of the destination for the regular LDPC-coded cooperation is deduced, and then the corresponding treble/multiple layer Tanner graph is introduced. Based on the treble/multiple layer Tanner graph, two joint iterative decoding algorithms are poposed, i.e., joint BP iterative decoding algorithm and joint MS iterative decoding algorithm.3. Quasi-cyclic LDPC(QC-LDPC) codes joint optimization for coded relay cooperation is investigated. Firstly, a kind of QC-LDPC codes constructed based on the base matrix and exponent matrix is introduced. Secondly, the impact of the cycles on the performance of QC-LDPC codes is analyzed in view of the Turbo iterative decoding principle. Meanwhile, for QC-LDPC codes constructed based on the base matrix and exponent matrix, a necessary and sufficient condition to avoid girth-4 cycles is proposed. Finally, more attention is paid to the coded relay cooperation system employing this kind of QC-LDPC codes. The characteristics of the cycles in the equalent check matrixs of coded single/multiple relay cooperation are analysed. Then a joint design algorithm of QC-LDPC codes for coded relay cooperation is proposed, which can cancel the girth-4 cycels of QC-LDPC codes adopted by the source, relays and destination.4. A special kind of pragmatic irregular LDPC codes, called repeat accumulate(RA) codes, is investigated. The RA-coded multi-relay cooperation based on virtual V-BLAST processing is proposed. In this system, two detection and decoding algorithms are proposed in the destination, i.e., MMSE-SIC-based serial detection and decoding algorithm and MAP-based joint iterative detection and decoding algorithm, where MIMO detector and LDPC joint iterative decoder cooperate in serial and Turbo iterative way, respectively.
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