低密度奇偶校验(Low Density Parity Check, LDPC)编码协作结合了LDPC码技术和协作技术，既能获得LDPC码带来的高编码增益，又能获得协作技术带来的分集增益等优势。针对LDPC码编码复杂度较高、存储空间资源消耗较大的问题，本项目研究一种基阵和指数阵构造的准循环低密度奇偶校验码 (Quasi-Cyclic LDPC, QC-LDPC)，提出短环消除算法进一步提升编码增益。针对多信源协作系统，引入网络编码技术提升系统平均吞吐量。深入研究基于网络编码与QC-LDPC码的多信源协作系统，推导网络编码、信源节点和协作中继采用的QC-LDPC码的联合校验矩阵，基于此校验矩阵，进一步联合设计网络编码与QC-LDPC码；依据整个协作系统的等效联合Tanner图概念，研究高效联合迭代译码算法。从而实现高编码增益与分集增益、高平均吞吐量、低复杂度、低存储资源消耗的可靠通信。

By combining low density parity check (LDPC) codes with cooperation techniques, LDPC-coded cooperation obtains both high coding gain and diversity gain. Considering the high complexity and high memory consumption of LDPC encoding, we will investigate a kind of quasi-cyclic LDPC (QC-LDPC) codes constructed on the basis of the base matrix and exponent matrix and propose the short-girth cycles cancellation algorithm to improve the coding gain. Furthermore, network coding will be employed in the multisource cooperation system to improve its average throughout. We will focus on the multisource cooperation system based on the network coding and QC-LDPC codes. The overall parity-check matrix, which corresponds to the network coding and QC-LDPC codes employed by the sources and relays, will be derived. Based on the overall parity-check matrix, we will jointly design the network coding and QC-LDPC codes. Based on the equivalent joint Tanner graph corresponding to the overall cooperation system, the efficient iterative decoding for the multisource cooperation system will be performed. Hence, the high diversity gain and coding gain, high average throughout, low implementation complexity and low memory consumption reliable communication system can be achieved.