LDPC-Polar级联系统的中间信道选择与分配

Intermediate Channels Selection and Allocation for LDPC-Polar Concatenated System

传统LDPC-Polar级联系统的中间信道选择方法对于非二进制擦除信道并不合适,并且没有考虑中间信道和LDPC码变量节点的对应关系。为此,提出利用关键集(Critical Sets,CS)构造新的中间信道挑选集合,并利用偏序和叶子集大小作为排序规则对中间信道可靠度进行排序。在所提出中间信道选择和排序方法的基础上,设计了一种中间信道和外码LDPC码变量节点的分配方法进一步提升级联系统的误码性能。仿真结果表明,当极化码码长为1024,级联系统码率为0.5时,在误块率(Block Error Rate,BLER)为10^(-3)处,所提方法相比于比特映射的方法约有0.14 dB的增益,与CA-SCL(Cyclic Redundancy Check Aided Successive Cancellation List)(L=2)译码算法相比约有0.3 dB的增益;并且相对于CA-SCL译码算法,该级联系统具有更低的译码时延。

The intermediate channels selection method of traditional concatenated system is not suitable for non-binary erasure channels,and the correspondence between intermediate channels and the variable nodes of LDPC codes is not considered.The authors propose a method to construct a new intermediate channels selection set using Critical Sets(CS),and uses the partial order and leaf set size as sorting rules to sort the reliability of intermediate channels.On the basis of the proposed intermediate channels selection and sorting method,a new allocation method of intermediate channels and the variable nodes of LDPC codes is designed to further improve the error performance of the concatenated system.Simulation results show that the proposed method at 10^(-3) block error rate(BLER)has a gain of about 0.14 dB over the bit mapping method and 0.3 dB over the Cyclic Redundancy Check Aided Successive Cancellation List(CA-SCL)(L=2)decoding algorithm when the length of the polar codes is 1024 and the code rate of the concatenated system is 0.5.And compared with the CA-SCL decoding algorithm,the concatenated system has lower decoding delay.