LT码的标记重传BP译码算法

当通信系统允许反馈时,LT码可以利用重传信息分组获得良好的性能,但是多次请求重传造成接收端等待时间过长,导致整个译码时间增加.为了减少重传次数和译码时间,提出了MR-BP(mark and retransmission belief propagation)译码算法.在BP(belief propagation)译码失败后,利用标记向量标记需要重传的信息分组,选取标记的信息分组.假设这个信息分组已经解码,把向量与分组的值作为整体继续BP译码.接收端只需要收到请求标记矩阵中标记的信息分组即可成功解码.MR-BP译码算法不仅解决了BP译码算法失败率大的问题,而且一次请求信息分组也明显地减少了译码时间.经过仿真验证,在重传分组数相同的情况下,译码时间明显减少.

Mark and retransmission BP decoding algorithm for LT codes

When the communication system allows feedback, LT codes can retransmit the information symbol to obtain good performance. But multiple retransmission requests cause the receiving end wait too long, and result in increasing the decoding time. In order to reduce the number of retransmissions reduce decoding time the number of retransmissions and reduce decoding time,a MR-BP (Mark and retransmission belief propagation) decoding algorithm for LT codes is proposed in this paper. When there is BP decoding failure, a mark vector is used to mark the information packets that need to be retransmitted and assume that this information packet has been decoded. The value of packets and the vector are as a whole and conduct BP decoding. The receiver can successfully decode after receiving the request information packets that are marked in the mark matrix. MR-BP decoding algorithm not only solves the problem of decoding failure after BP decoding, but only one request for information packet also greatly reduces the decoding time. The simulations show that, in the case of the same packet retransmission number, the decoding time is significantly reduced.