Joint Design of Source-Channel Codes with Linear Source Encoding Complexity and Good Channel Thresholds Based on Double-Protograph LDPC Codes

TL;DR

This paper introduces a novel design for joint source-channel coding using double-protograph LDPC codes with triangular sub-base matrices, resulting in improved channel thresholds and error rate performance.

Contribution

It proposes replacing the identity matrix with triangular sub-base matrices in DP-LDPC JSCC, enhancing theoretical and simulated performance over traditional designs.

Findings

Channel threshold improved by up to 0.41 dB

Source symbol error rate improved by up to 0.5 dB

Design demonstrates better performance in simulations

Abstract

We propose the use of a lower or upper triangular sub-base matrix to replace the identity matrix in the source-check-channel-variable linking protomatrix of a double-protograph low-density parity-check joint-source-channel code (DP-LDPC JSCC). The elements along the diagonal of the proposed lower or upper triangular sub-base matrix are assigned as "1" and the other non-zero elements can take any non-negative integral values. Compared with the traditional DP-LDPC JSCC designs, the new designs show a theoretical channel threshold improvement of up to 0.41 dB and a simulated source symbol error rate improvement of up to 0.5 dB at an error rate of 1e-6.