基于软门限LDPC码的中继信道容量实现

Realization of the capacity in relay channel based on LDPC codes with soft threshold

LDPC(Lowdensity parity code)码是逼近香农界的信道码。为了逼近香农界,其优化一般采用硬门限准则。但当信道容量小于编码码率时,LDPC无法正确译码。因此,提出从软门限的角度优化LDPC码,使得在码率超过信道容量时,接收端仍可以部分译码,并将该LDPC码用于单中继信道中,解决使用解码前传(DF,decode and forward)的中继信道容量瓶颈问题,进而提高信道容量。还考虑中继节点使用Slepian-Wolf信源编码,降低中继节点到目的节点的信道质量要求的同时,仍能保证无失真译码。

LDPC is a good channel code,whose performance approaches Shannon limitation with the optimization of LDPC based on soft threshold criteria.When channel capacity is lower than code rate,LDPC won＇t be decoded correctly.This paper proposes the optimization of LDPC according to soft threshold to decode LDPC partly even when the code rate is larger than channel capacity.Optimized LDPC codes are used in relay channel to resolve the capacity bottleneck problem with decode and forward,therefore increase the channel capacity.This paper also considers the utilization of Slepian-Wolf source coding in order to decrease the requiring channel quality from relay node to destination node.