Efficient adaptive successive cancellation list decoders for polar codes

As improved versions of the successive cancellation (SC) decoder, the adaptive SC list (SCL) decoder and the segmented CRC-aided SCL (SCA-SCL) decoder can achieve notable complexity reduction compared to the traditional SCL one. However, the former only shows good reduction in high SNR region whereas the latter only works good in low SNR region. To this end, two novel efficient adaptive SCL decoding schemes are proposed to achieve good complexity reduction in both low and high SNR regions. The first one is adaptive SCA-SCL (ASCA-SCL) decoder, which is based on SCA-SCL but with varying list size. The second one is adaptive switching SCL (AS-SCL) decoder, whose list reduction metric switches with regarding to specific SNR value. Numerical results have shown that for (1024, 512) polar code and list size L = 2, compared to the state-of-the-art decoder, the proposed ASCA-SCL decoder and AS-SCL decoder can achieve up to 45.40% and 32.39% computational complexity reduction respectively, while keeping the similar decoding performance.