中文摘要：

基于部分符号更新策略的BP（Belief Propagation）译码算法减少了LDPC（Low-Density Parity-Check）码的译码运算量，提高了译码效率。然而在其译码过程中，由于变量节点可靠性判决准确率不高，而且可靠性被误判的错误节点无法在后继的译码中得到修正，译码性能大大降低。该文提出一种改进的节点可靠性判决准则，提高迭代过程中对变量节点可靠性判断的准确率；同时，在每次迭代结束后，重新衡量所有变量节点的可靠性，以此来消除可靠性误判对译码性能的影响。仿真结果表明，改进的算法不仅使传统BP译码的复杂度降低，而且提高了BP算法的译码性能。

英文摘要：

BP （Belief Propagation） decoding based on reliability updating schedule reduces the computational complexity and improves the decoding efficiency. However, the poor Bit Error Rate （BER） performance of the decoding appears due to the low accuracy of reliability criteria and the wrong bits which are no longer update. Therefore, an improved reliability criteria and modified updating schedule are proposed to increase the accuracy of the criteria. The simulation results show that the proposed algorithm can reduce the computational complexity and improve the decoding performance of conventional BP algorithm.