Efficient stochastic successive cancellation list decoder for polar codes
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. RESEARCH PAPER .
October 2020, Vol. 63 202303:1–202303:19 https://doi.org/10.1007/s11432-019-2924-6
Efficient stochastic successive cancellation list decoder for polar codes Xiao LIANG1,2,3,4† , Huizheng WANG1,2,3,4† , Yifei SHEN1,2,3,4 , Zaichen ZHANG1,2,3,4, Xiaohu YOU1,2,3,4 & Chuan ZHANG1,2,3,4* 1
Laboratory of Efficient Architectures for Digital-communication and Signal-processing (LEADS), Southeast University, Nanjing 211100, China; National Mobile Communications Research Laboratory, Southeast University, Nanjing 211100, China; 3 Quantum Information Center of Southeast University, Nanjing 211100, China; 4 Purple Mountain Laboratories, Nanjing 211100, China
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Received 29 December 2019/Revised 13 March 2020/Accepted 22 May 2020/Published online 21 September 2020
Abstract Polar codes are one of the most favorable capacity-achieving codes owing to their simple structures and low decoding complexity. Successive cancellation list (SCL) decoders with large list sizes achieve performances very close to those of maximum-likelihood (ML) decoders. However, hardware cost is a severe problem because an SCL decoder with list size L consists of L copies of a successive cancellation (SC) decoder. To address this issue, a stochastic SCL (SSCL) polar decoder is proposed. Although stochastic computing can achieve a good hardware reduction compared with the deterministic one, its straightforward application to an SCL decoder is not well-suited owing to the precision loss and severe latency. Therefore, a doubling probability approach and adaptive distributed sorting (DS) are introduced. A corresponding hardware architecture is also developed. Field programmable gate array (FPGA) results demonstrate that the proposed stochastic SCL polar decoder can achieve a good performance and complexity tradeoff. Keywords
SCL polar decoder, stochastic computing, 2-bit decoding, distributed sorting, hardware
Citation Liang X, Wang H Z, Shen Y F, et al. Efficient stochastic successive cancellation list decoder for polar codes. Sci China Inf Sci, 2020, 63(10): 202303, https://doi.org/10.1007/s11432-019-2924-6
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Introduction
Polar codes, proposed by Arıkan’s breakthrough paper [1], are an exciting new class of channel codes that can asymptotically achieve the capacity for symmetric binary-input discrete memoryless channels. Because of its FFT-like structure and low complexity with O(N log N ) where N denotes code length, successive cancellation (SC) decoding algorithm has become one of the most popular polar decoding algorithms. Nevertheless, it cannot be denied that compared to maximum likelihood (ML) decoder [2], the decoding performance of SC polar decoder still suffers from an evident degradation. To narrow the performance gap caused by the sub-optimality of traditional successive cancellation decoder, the successive cancellation list (SCL) polar decoding algorithm is developed in [2, 3]. Simulation results have revealed that SCL polar decoder can outperform the low density parity check (LDPC) codes even within high error-rate reg
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