Polar codes are a class of error-correcting codes that provably achieve the capacity of practical channels. The successive-cancellation flip (SCF) decoder is a low-complexity decoder that was proposed to improve the performance of the successive-cancellation (SC) decoder as an alternative to the high-complexity successive-cancellation list (SCL) decoder. The SCF decoder improves the error-correction performance of the SC decoder, but the variable execution time and the high worst-case execution time pose a challenge for the realization of receivers with fixed-time algorithms. The dynamic SCF (DSCF) variation of the SCF decoder further improves the error-correction performance but the challenge of decoding delay remains. In this work, we propose a simplified restart mechanism (SRM) that reduces the execution time of SCF and DSCF decoders through conditional restart of the additional trials from the second half of the codeword. We show that the proposed mechanism is able to improve the execution time characteristics of SCF and DSCF decoders while providing identical error-correction performance. For a DSCF decoder that can flip up to 3 simultaneous bits per decoding trial, the average execution time, the average additional execution time and the execution-time variance are reduced by approximately 31%, 37% and 57%, respectively. For this setup, the mechanism requires approximately 3.9% additional memory.

翻译：极化码是一类能够确凿逼近实际信道容量的纠错码。连续消除翻转（SCF）译码器是一种低复杂度译码器，旨在作为高复杂度连续消除列表（SCL）译码器的替代方案，以提升连续消除（SC）译码器的性能。SCF译码器改善了SC译码器的纠错性能，但其可变执行时间及较高的最坏情况执行时间给采用固定时间算法的接收机实现带来了挑战。SCF译码器的动态SCF（DSCF）变体进一步提升了纠错性能，但译码延迟问题依然存在。本文提出了一种简化重启机制（SRM），通过从码字后半部分有条件地重启附加尝试，减少了SCF和DSCF译码器的执行时间。我们证明，所提机制能够在保持相同纠错性能的同时，改善SCF和DSCF译码器的执行时间特性。对于每次译码尝试最多可翻转3个同步比特的DSCF译码器，平均执行时间、平均附加执行时间和执行时间方差分别降低了约31%、37%和57%。在此设置下，该机制需额外占用约3.9%的存储空间。