A high throughput belief propagation decoder architecture for polar codes
Jun Ting Lin, Jin Sha, Li Li, Chenrong Xiong, Zhiyuan Yan, Zhongfeng Wang · 2016
The belief propagation (BP) decoding algorithm not only is an alternative to the successive cancelation (SC) decoders of polar codes, but also provides soft outputs that are necessary for joint detection and decoding. The BP decoders with the flooding schedule achieve high throughput with excessive hardware cost especially when the block length is large. The soft-cancelation (SCAN) decoders for polar codes have reduced memory complexity compared to the BP decoders based on the flooding schedule. The simplified SC aided reduced complexity soft-cancelation (S-RCSC) decoders further reduce the computational and memory complexity of the SCAN decoders at the cost of negligible error performance degradation. Both the SCAN and S-RCSC decoders have limited throughput due to their serial decoding schedules. In this paper, we first propose an improved S-RCSC (IS-RCSC) decoding algorithm and then present a high throughput decoder architecture based on our IS-RCSC algorithm. Our IS-RCSC decoding algorithm performs the message passing on a binary tree representation of a polar code. Compared to the S-RCSC decoding algorithm, our IS-RCSC decoding algorithm accelerates the computing of the returned soft messages when certain types of nodes are activated. The corresponding hardware architecture of our IS-RCSC decoder is also proposed. In terms of area efficiency, the hardware implementation results demonstrate that our IS-RCSC decoders are 19% to 43% better than decoders in the literature.