# A Multi-Gbps Unrolled Hardware List Decoder for a Systematic Polar Code

## TL;DR

This paper presents a high-speed, hardware-implemented list decoder for polar codes that achieves multi-Gbps throughput and competitive error correction, using unrolled architecture adapted for SCL decoding.

## Contribution

It introduces an unrolled hardware design for SCL polar decoding, enabling multi-Gbps throughput with high energy efficiency, which was not previously achieved.

## Key findings

- Achieves over 10 Gbps throughput at 468 MHz
- Energy efficiency of 7.25 pJ/bit in 28 nm CMOS
- Competitive error correction performance with LDPC codes

## Abstract

Polar codes are a new class of block codes with an explicit construction that provably achieve the capacity of various communications channels, even with the low-complexity successive-cancellation (SC) decoding algorithm. Yet, the more complex successive-cancellation list (SCL) decoding algorithm is gathering more attention lately as it significantly improves the error-correction performance of short- to moderate-length polar codes, especially when they are concatenated with a cyclic redundancy check code. However, as SCL decoding explores several decoding paths, existing hardware implementations tend to be significantly slower than SC-based decoders. In this paper, we show how the unrolling technique, which has already been used in the context of SC decoding, can be adapted to SCL decoding yielding a multi-Gbps SCL-based polar decoder with an error-correction performance that is competitive when compared to an LDPC code of similar length and rate. Post-place-and-route ASIC results for 28 nm CMOS are provided showing that this decoder can sustain a throughput greater than 10 Gbps at 468 MHz with an energy efficiency of 7.25 pJ/bit.

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Source: https://tomesphere.com/paper/1702.00938