Improved multiple folded successive cancellation decoder for polar codes

Folding is a technique to modify the decoder graph of polar codes based on successive cancellation decoding (SCD). Folding was proposed in [1] and extended to multiple folding (κ times) in [2] as a technique to significantly reduce the latency of the SCD of polar codes up to a factor of 2^K, without performance loss. The extension in [2] shows folding only for κ ≤ 3 due to the rapidly increasing complexity. In this paper, we propose an alternative implementation of the multiple-folding SC decoder, to significantly reduce its complexity. The complexity of the new algorithm is only slightly higher than that of the original SCD for polar codes. As a result, the new algorithm enables to decode longer codes with larger ks, which exhibit significant performance gains, in addition to the latency gain.