A Sequence Repetition Node-Based Successive Cancellation List Decoder for 5G Polar Codes: Algorithm and Implementation

TL;DR

This paper introduces a generalized sequence repetition node for SCL decoding of 5G polar codes, significantly improving decoding speed and hardware efficiency through algorithmic and implementation optimizations.

Contribution

It extends the SR node to SCL decoding, presents the first SR-List decoder implementation, and optimizes it for 5G NR polar codes, achieving nearly double the throughput of existing methods.

Findings

Almost 2x throughput improvement over state-of-the-art decoders

Achieves 2.94 Gbps throughput in hardware implementation

Supports all 5G NR polar codes with high area efficiency

Abstract

Due to the low-latency and high-reliability requirements of 5G, low-complexity node-based successive cancellation list (SCL) decoding has received considerable attention for use in 5G communications systems. By identifying special constituent codes in the decoding tree and immediately decoding these, node-based SCL decoding provides a significant reduction in decoding latency compared to conventional SCL decoding. However, while there exists many types of nodes, the current node-based SCL decoders are limited by the lack of a more generalized node that can efficiently decode a larger number of different constituent codes to further reduce the decoding time. In this paper, we extend a recent generalized node, the sequence repetition (SR) node to SCL decoding and we describe the first implementation of an SR-List decoder. By merging certain SR-List decoding operations and applying various optimizations for 5G New Radio (NR) polar codes, our optimized SR-List decoding algorithm increases the throughput by almost ${2\times}$ compared to a similar state-of-the-art node-based SCL decoder. We also present our hardware implementation of the optimized SR-List decoding algorithm which supports all 5G NR polar codes. Synthesis results show that our SR-List decoder can achieve a $2.94 \, \mathrm{Gbps}$ throughput and $6.70\, \mathrm{Gbps} / \mathrm{mm}^2$ area efficiency for ${L=8}$.