In this work, we investigate the performance of polar codes with the assistance of feedback in communication systems. Although it is well known that feedback does not improve the capacity of memoryless channels, we show that the finite length performance of polar codes can be significantly improved as feedback enables genie-aided decoding and allows more flexible thresholds for the polar coding construction. To analyze the performance under the new construction, we then propose an accurate characterization of the distribution of the error event under the genie-aided successive cancellation (SC) decoding. This characterization can be also used to predict the performance of the standard SC decoding of polar codes with rates close to capacity.

翻译：本文研究了通信系统中在反馈辅助下Polar码的性能表现。尽管反馈不能提升无记忆信道的容量已是公认结论，但我们证明：通过反馈实现"精灵辅助"解码并为Polar码构造提供更灵活的阈值选择，可显著改善Polar码的有限码长性能。为分析新构造下的性能表现，我们进而提出了精灵辅助连续消除（SC）解码中误码事件分布的精确刻画方法。该刻画同样适用于预测接近容量极限时标准SC解码下Polar码的性能表现。