Rate-Compatible Protograph-based LDPC Codes for Inter-Symbol Interference Channels

TL;DR

This paper introduces a family of rate-compatible protograph-based LDPC codes that approach the capacity of ISI channels, addressing the complex joint design of structured codes and channel states.

Contribution

It presents a novel method to design nested high-rate protograph codes and extend them to create rate-compatible codes for ISI channels.

Findings

Codes have thresholds close to the i.u.d. capacity

Numerical simulations confirm the effectiveness

Design method handles joint code and channel state complexity

Abstract

This letter produces a family of rate-compatible protograph-based LDPC codes approaching the independent and uniformly distributed (i.u.d.) capacity of inter-symbol interference (ISI) channels. This problem is highly nontrivial due to the joint design of structured (protograph-based) LDPC codes and the state structure of ISI channels. We describe a method to design nested high-rate protograph codes by adding variable nodes to the protograph of a lower rate code. We then design a family of rate-compatible protograph codes using the extension method. The resulting protograph codes have iterative decoding thresholds close to the i.u.d. capacity. Our results are supported by numerical simulations.