半双工中继信道下联合LDPC码设计

为了提高解码前传半双工中继通信系统的编码增益，提出了一种联合LDPC码编码结构及其度分布优化方法。该结构视信源和中继子码为联合LDPC码的一部分，目的端根据从信源和中继接收的消息进行联合译码，同时获得信源和中继的信息。为了分析联合LDPC码的渐进性能，推导了AWGN信道下联合LDPC码的高斯近似密度进化算法。结合译码收敛条件和度分布约束关系，提出联合LDPC码的度分布优化问题。仿真结果表明：联合LDPC码的渐进性能及误码性能优于BE-LDPC码和独立处理（SP）码。

Jointed LDPC codes design for half-duplex relay channels

In order to increase the coding gain of decode-and-forward half-duplex relay channel, a jointed LDPC coding structure and its corresponding optimization scheme was proposed. Novel structure made the subcodes of both source and relay nodes as parts of the overall code. Using the messages from the source and the relay, the destination could decode the information of the source and relay nodes simultaneously. To analyze the asymptotic coding gain of jointed LDPC codes, the iterative decoding convergence condition was derived in AWGN channel. Combining the iterative decoding convergence condition and the degree distribution constraint, the optimization problem of the jointed LDPC code degree distribution was presented. The simulation results show that jointed LDPC codes outperform both BE-LDPC codes and SP codes.