Process-and-Forward: Deep Joint Source-Channel Coding Over Cooperative Relay Networks

TL;DR

This paper presents deep joint source-channel coding schemes for image transmission over cooperative relay networks, utilizing neural networks and transformer models to improve performance over traditional methods in various relay configurations.

Contribution

Introduction of DeepJSCC-PF with transformer-based relay models and adaptive transmission strategies for enhanced image transmission in cooperative relay networks.

Findings

DeepJSCC-PF outperforms BPG in image quality at maximum rate.

Transformer-based relay models learn to generate correlated signals for beamforming.

Proposed methods work effectively over AWGN and Rayleigh fading channels.

Abstract

We introduce deep joint source-channel coding (DeepJSCC) schemes for image transmission over cooperative relay channels. The relay either amplifies-and-forwards its received signal, called DeepJSCC-AF, or leverages neural networks to extract relevant features from its received signal, called DeepJSCC-PF (Process-and-Forward). We consider both half- and full-duplex relays, and propose a novel transformer-based model at the relay. For a half-duplex relay, it is shown that the proposed scheme learns to generate correlated signals at the relay and source to obtain beamforming gains. In the full-duplex case, we introduce a novel block-based transmission strategy, in which the source transmits in blocks, and the relay updates its knowledge about the input signal after each block and generates its own signal. To enhance practicality, a single transformer-based model is used at the relay at each block, together with an adaptive transmission module, which allows the model to seamlessly adapt to different channel qualities and the transmission powers}. Simulation results demonstrate the superior performance of DeepJSCC-PF compared to the state-of-the-art BPG image compression algorithm operating at the maximum achievable rate of conventional decode-and-forward and compress-and-forward protocols, in both half- and full-duplex relay scenarios over AWGN and Rayleigh fading channels.