基于相对残差的LDPC码动态调度译码算法

针对低密度奇偶校验码的动态调度译码算法中存在的震荡现象和贪婪特性问题，在基于变量节点消息残差置信传播算法的基础上，提出一种基于相对残差调度的置信传播算法。对变量节点进行分组，以变量节点向校验节点传递消息的相对残差值作为参考，优先更新相对残差值最大的节点，加快译码收敛速度。对于译码过程中震荡的变量节点，对其更新前后的后验LLR(log likelihood ratio)消息值做加权平均处理，提高震荡节点的可靠度。在算法迭代的过程中对变量节点向校验节点传递消息的相对残差值作衰减处理，缓解译码算法的贪婪特性。仿真结果表明：与VC-RBP算法相比，在误比特率为10-5时所提算法译码性能可以获得0.3～0.4 dB的增益，同时拥有更快的收敛速度。

Relative-Residual-Based Dynamic Schedule for Decoding of LDPC Codes

In order to solve the problems of the oscillation phenomenon and greedy characteristics in the dynamic scheduling decoding algorithm for low-density parity-check (LDPC) codes, the relative-residual-based dynamic schedule (RRB-BP) algorithm is proposed based on variable-to-check residual belief propagation (VC-RBP) algorithm. The variable nodes are grouped, then the relative residual value of the message passed by the variable nodes to the check node is taken as a reference, and the node with the largest relative residual value is updated in priority to accelerate the decoding convergence speed. For variable nodes oscillating in the decoding process, the posterior LLR (log likelihood ratio) message values before and after updating are processed with weighted average to improve the reliability of oscillating nodes. In the process of algorithm iteration, the relative residual value of messages transmitted from variable node to check node is attenuated to alleviate the greedy characteristic of decoding algorithm. The simulation results show that compared with the VC-RBP algorithm, the decoding performance gain of the proposed algorithm is 0.3~0.4 dB when the bit error rate is 10^-5, and the convergence speed is faster.