Rate-Flexible Fast Polar Decoders

TL;DR

This paper introduces a novel rate-flexible fast SC-based polar decoder that generates operation lists directly in hardware, significantly reducing area and enabling efficient decoding across various 5G code rates.

Contribution

The paper presents a hardware implementation of a rate-flexible fast SC-based polar decoder, overcoming the rate dependency issue of previous decoders.

Findings

Area occupation is only 38% of the baseline decoder for 5G code rates.

The proposed decoder supports multiple code rates with low complexity.

Hardware implementation achieves high decoding speed and flexibility.

Abstract

Polar codes have gained extensive attention during the past few years and recently they have been selected for the next generation of wireless communications standards (5G). Successive-cancellation-based (SC-based) decoders, such as SC list (SCL) and SC flip (SCF), provide a reasonable error performance for polar codes at the cost of low decoding speed. Fast SC-based decoders, such as Fast-SSC, Fast-SSCL, and Fast-SSCF, identify the special constituent codes in a polar code graph off-line, produce a list of operations, store the list in memory, and feed the list to the decoder to decode the constituent codes in order efficiently, thus increasing the decoding speed. However, the list of operations is dependent on the code rate and as the rate changes, a new list is produced, making fast SC-based decoders not rate-flexible. In this paper, we propose a completely rate-flexible fast SC-based decoder by creating the list of operations directly in hardware, with low implementation complexity. We further propose a hardware architecture implementing the proposed method and show that the area occupation of the rate-flexible fast SC-based decoder in this paper is only $38\%$ of the total area of the memory-based base-line decoder when 5G code rates are supported.