Enhanced Bit-Flipping Successive Cancellation Decoding for Convolutional Polar Codes

The paper presents an enhanced bit-flipping (BF) successive cancellation (SC) decoding method under limited cyclic redundancy checks (CRC). Although BF-SC decoding achieves comparable performance to SC list decoding via a series of SC decodings, the existing methods are inevitably impaired under limited CRC checks, which is the case during blind detection in physical downlink control channel. To this end, we propose a path-metric-assisted BF-SC method, which before CRC checks filters the clearly erroneous decodings and further prioritizes the ones more likely to be correct. Combined with convolutional polar codes - a recently-proposed encoding method with substantial coding gain but same $2x2$ kernel as the original polar, the proposed method is demonstrated to outperform the reference polar code settings in the current 5G standard even with limited CRC checks.