Coding for Channels with SNR Variation: Spatial Coupling and Efficient Interleaving

TL;DR

This paper introduces a novel spatially-coupled coding scheme with efficient interleaving for channels with SNR variation, significantly improving error correction performance over traditional block codes.

Contribution

It presents a new partitioning technique for SC codes, a construction tailored for SNR-varying channels, and a low-complexity interleaving scheme to enhance error correction.

Findings

SC codes outperform block codes by over 100x in error floor region

The proposed interleaving scheme further improves performance

Performance gains increase with higher memory and column weight

Abstract

In magnetic-recording systems, consecutive sections experience different signal to noise ratios (SNRs). To perform error correction over these systems, one approach is to use an individual block code for each section. However, the performance over a section affected by a lower SNR is weaker compared to the performance over a section affected by a higher SNR. Spatially-coupled (SC) codes are a family of graph-based codes with capacity approaching performance and low latency decoding. An SC code is constructed by partitioning an underlying block code to several component matrices, and coupling copies of the component matrices together. The contribution of this paper is threefold. First, we present a new partitioning technique to efficiently construct SC codes with column weights 4 and 6. Second, we present an SC code construction for channels with SNR variation. Our SC code construction provides local error correction for each section by means of the underlying codes that cover one section each, and simultaneously, an added level of error correction by means of coupling among the underlying codes. Third, we introduce a low-complexity interleaving scheme specific to SC codes that further improves their performance over channels with SNR variation. Our simulation results show that our SC codes outperform individual block codes by more than 1 and 2 orders of magnitudes in the error floor region compared to the block codes with and without regular interleaving, respectively. This improvement is more pronounced by increasing the memory and column weight.