Design of Joint Source-Channel Codes Based on a Generic Protograph

TL;DR

This paper introduces a novel approach for designing joint source-channel codes using generic protographs, along with algorithms for analyzing and optimizing their thresholds, resulting in codes that approach Shannon limits.

Contribution

It presents a new protograph-based design framework and algorithms for joint source-channel coding, improving threshold performance over existing double-protograph methods.

Findings

Codes achieve channel thresholds within 1 dB of Shannon limit

Proposed algorithms effectively analyze source and channel thresholds

Generic-protograph JSCCs outperform double-protograph-based systems

Abstract

In this paper, we propose using a generic protograph to design joint source-channel codes (JSCCs). We present a generalized algorithm, called protograph extrinsic information transfer for JSCC algorithm (PEXIT-JSCC algorithm), for analyzing the channel threshold of the proposed JSCC. We also propose a source generic protograph EXIT (SGP-EXIT) algorithm, which is more appropriate than the generalized source protograph extrinsic information transfer (GSP-EXIT) algorithm, for evaluating the source threshold of a generic protograph. Moreover, a collaborative optimization method based on the SGP-EXIT and PEXIT-JSCC algorithms is proposed to construct generic-protograph JSCCs with good source and channel thresholds. Finally, we construct generic-protograph JSCCs, analyze their decoding thresholds, and compare their theoretical and error performance with JSCC systems based on optimized double-protographs. Results show that our proposed codes can attain channel thresholds within 1 dB from the Shannon limit and outperform double-protograph-based JSCCs.