A complexity-reduced fast successive cancellation list decoder for polar codes

A multi-bit decision for polar codes based on a simplified successive cancellation (SSC) decoding algorithm can improve the throughput of polar decoding. A list algorithm is used to improve the error-correcting performance. However, list decoders are highly complex compared with decoders without a list algorithm. In this paper, a low-complexity list decoder is proposed, where path-splitting operations for a multi-bit decision can be avoided, if the decoding reliability exceeds a threshold. The threshold is determined based on the reliability of subchannels and positions of decoding nodes. Path splitting rules are designed for multi-bit decision processes, and a complexity-reduced list decoder is proposed based on this. Results show that the number of survival paths can be greatly reduced at the cost of negligible deterioration in block error performance. Thus, the computational complexity can be significantly reduced, especially for a high signal-to-noise ratio (SNR) region.