极化码的多比特译码算法研究

Research on multi-bit decoding algorithms for polar codes

针对极化码的连续消除列表(successive cancellation list,SCL)译码算法的高时延问题,提出了基于对数似然比的多比特SCL(multi-bit SCL,MSCL)译码算法,可以在一个判决时刻同时译出多个码字比特,在不损失译码性能的前提下,将译码时延由3N-2个时钟降为4N/M-2个时钟,相比于现有的多比特SCL译码算法,MSCL译码算法具有更低的路径度量值计算复杂度。为了降低循环冗余校验(cyclical redundancy check,CRC)辅助的SCL(CRC aided SCL,CA-SCL)译码算法的译码时延以及存储空间,提出了分段CRC辅助的MSCL(segmented CRC-aided MSCL,SCA-MSCL)译码算法,并提出了分段信息码字长度修正算法,来保证在信息位索引集A不变的前提下,实现每一分段结尾处对应的信息位索引能够被M整除。SCA-MSCL算法可以借助多个CRC判决来尽可能早地输出译码码字,从而减少译码器的存储空间以及译码时延。

Aiming at the problem of high delay of successive cancellation lists (SCL)decoding algorithm for polar codes,a multi-bit SCL (MSCL)decoding algorithm based on log-likelihood ratio was proposed.The multiple codeword bits could be decoded simultaneously at a single decision time.Without loss of SCL decoding performance,the decoding delay was reduced from 3N-2clocks to 4N/M-2clocks.Compared with the existing multi-bit SCL decoding algorithm, the MSCL decoding algorithm had a lower complexity of the path metric calculation.In order to reduce the decoding delay and memory space of the cyclical redundancy check (CRC)assisted SCL (CA-SCL)decoding algorithm,a segmented CRC assisted MSCL (SCA-MSCL)decoding algorithm was proposed,and a segmentation information codeword length correction algorithm was proposed.By adjusting the length of the relevant segment,the information bit index set A was guaranteed.Under the same premise,the corresponding information bit index at the end of each segment could be divisible by M.The SCA-MSCL algorithm could output decoded code words as early as possible by using multiple CRC decisions,thereby reducing the decoder!s storage space and decoding delay.