基于可靠性函数的极化码PSS-RF-SCL译码算法

PSS-RF-SCL Decoding Algorithm of Polar Codes Based on the Reliability Function

摘要:

针对串行抵消列表下基于搜索集的路径分裂选择策略(Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List, PSS-SS-SCL)译码算法的缺陷,提出了基于可靠性函数的路径分裂策略和依靠辅助路径度量值(Auxiliary Path Metric, APM)的剪枝策略。在此基础上,提出了PSS-RF-SCL(Path Splitting Selecting strategy based on Reliability Function under the Successive Cancellation List)译码算法。该算法在译码阶段,每个信息比特在进行路径分裂前,计算所有路径的路径度量(Path Metric, PM)值。利用这些PM值计算出该比特的可靠性函数值。将可靠性函数值低于其平均值即阈值α的信息比特视为需要进行路径分裂的比特。使用该方法来识别分裂比特,明显减少了多余的分裂次数。此外,将APM值高于正确译码路径的APM平均值即阈值β的路径视为不可靠路径。对不可靠路径进行剪枝,明显降低了译码列表总数。仿真结果表明,相较于传统的基于搜索集的路径分裂策略辅助SCL译码算法,所提出的PSS-RF-SCL译码算法在没有性能损失的前提下,明显降低了译码复杂度。

Abstract:

To address the shortcomings of the Path Splitting Selecting strategy based on Search Set under the Successive Cancellation List (PSS-SS-SCL) decoding algorithm, a path splitting strategy based on reliability function and a pruning strategy relying on Auxiliary Path Metric (APM) are proposed. On the basis, the Path Splitting Selecting strategy based on Reliability Function under the Successive Cancellation List (PSS-RF-SCL) decoding algorithm is proposed. During the decoding of the algorithm, the Path Metric (PM) values for all paths is calculated before performing path splitting on each information bit. The reliability function value of the bit is calculated by using these PM values. Information bits with reliability function values below its average value (namely, the threshold α) are considered as the bits that require path splitting. This method is used to identify the splitting bits and significantly reduces the splitting number. In addition, paths with APM values above the APM average value (namely, the threshold β) of the correct decoding path are considered the unreliable paths. Pruning the unreliable paths significantly reduces the total number of decoding lists. The simulation results show that compared to the traditional path splitting decoding algorithms based on search sets, the proposed PSS-RF-SCL decoding algorithm significantly reduces the decoding complexity without the performance loss.