Connecting Spatially Coupled LDPC Code Chains for Bit-Interleaved Coded Modulation

TL;DR

This paper proposes a novel connected-chain SC-LDPC code design for BICM that enhances decoding performance and exploits UEP, outperforming existing schemes through joint code and bit mapping optimization.

Contribution

It introduces a new connected-chain ensemble design and joint bit mapping strategy to improve performance and UEP in SC-LDPC codes for BICM.

Findings

Connected-chain ensembles outperform single-chain in decoding.

Joint design enhances UEP and decoding performance.

Numerical results confirm superiority over existing methods.

Abstract

This paper investigates the design of spatially coupled low-density parity-check (SC-LDPC) codes constructed from connected-chain ensembles for bit-interleaved coded modulation (BICM) schemes. For short coupling lengths, connecting multiple SC-LDPC chains can improve decoding performance over single-chains and impose structured unequal error protection (UEP). A joint design of connected-chain ensembles and bit mapping to further exploit the UEP from codes and high-order modulations is proposed. Numerical results demonstrate the superiority of the proposed design over existing connected-chain ensembles and over single-chain ensembles with existing bit mapping design.