Joint Network-Channel Coding for the Asymmetric Multiple-Access Relay Channel

In this paper, the authors consider the time-division Multiple Access Relay Channel (MARC). They propose a low-complexity compress-and-forward-based transmission scheme that consists of a scalar quantization of Log-Likelihood Ratios (LLRs), followed by a suitably defined network code. This scheme is well suited also for asymmetric source-relay channel conditions. They use the Information Bottleneck Method (IBM) for designing the LLR quantizers and they propose a modified IBM algorithm with more favorable numerical properties. Finally, they assess the performance of the proposed scheme in AWGN and fading channels using numerical simulations, including a comparison with existing transmission schemes.