Polar codes have attracted the attention of numerous researchers in the past decade due to their excellent performance. However, their performance at short block lengths under standard successive cancellation decoding is far from desirable. An effective method to improve the performance at short lengths is CRC precoding followed by successive-cancellation list decoding. Later, Arikan presented polarization-adjusted convolutional (PAC) codes, which further improve the performance of polar codes. In fact, bit-flipping is another post-processing method that can improve decoding performance. In this paper, we propose a novel SCL Bit-Flipping of PAC Codes. We show that better performance can be achieved using list decoding when the list size is the same for PAC codes (N=128, K=64). The decoding performance of our newly proposed PAC-SCLF with a list size of 32 is 0.3 dB better than that of the traditional PAC-SCL with a list size of 32. We set the maximum number of bit flips to 5. The performance of the list size (L=32) for PAC-SCLF is almost the same as the performance of the list size (L=128) for PAC-SCL.

翻译：过去十年间，极化码因其优异性能吸引了众多研究者的关注。然而，在标准连续消除译码算法下，其短码长性能远未达到理想水平。采用CRC预编码结合连续消除列表译码是改善短码长性能的有效手段。此后，Arikan提出极化调整卷积码，进一步提升了极化码性能。实际上，比特翻转是另一种能提升译码性能的后处理方法。本文提出一种新型PAC码的SCL比特翻转译码算法。研究结果表明，当PAC码（N=128, K=64）采用相同列表大小时，列表译码可实现更优性能。我们新提出的PAC-SCLF译码器在列表大小为32时的译码性能，比传统列表大小为32的PAC-SCL译码器提升0.3 dB。我们将最大比特翻转次数设为5。列表大小L=32的PAC-SCLF译码性能与列表大小L=128的PAC-SCL译码性能几乎持平。