An Optimal Unequal Error Protection LDPC Coded Recording System

TL;DR

This paper develops an LDPC coding scheme with unequal error protection for RLL constrained recording systems, improving error correction for flipped bits through optimized code design and decoding analysis.

Contribution

It introduces a novel UEP LDPC coding framework with allocation and labeling strategies, combined with density evolution and EXIT analysis, for enhanced RLL constrained recording performance.

Findings

Optimized LDPC code distribution improves error correction.

Density evolution and EXIT analysis validate the proposed design.

Differential evolution finds the best code distribution.

Abstract

For efficient modulation and error control coding, the deliberate flipping approach imposes the run-length-limited(RLL) constraint by bit error before recording. From the read side, a high coding rate limits the correcting capability of RLL bit error. In this paper, we study the low-density parity-check (LDPC) coding for RLL constrained recording system based on the Unequal Error Protection (UEP) coding scheme design. The UEP capability of irregular LDPC codes is used for recovering flipped bits. We provide an allocation technique to limit the occurrence of flipped bits on the bit with robust correction capability. In addition, we consider the signal labeling design to decrease the number of nearest neighbors to enhance the robust bit. We also apply the density evolution technique to the proposed system for evaluating the code performances. In addition, we utilize the EXIT characteristic to reveal the decoding behavior of the recommended code distribution. Finally, the optimization approach for the best distribution is proven by differential evolution for the proposed system.