Joint Channel and Network Code Design for Half-Duplex Multiple-Access Relay System

We consider the joint channel and network code design for a half-duplex 4-node multiple-access relay system with two sources, one relay, and one destination. The relay combines the information from both sources and transmits it to the destination together with both sources. We consider two network coding schemes for information combining at the relay, namely, the superposition coding (SC) and the Raptor coding (RC). For both SC and RC, the profiles for joint channel and network coding are optimized based on the extrinsic information transfer (EXIT) function analysis. For both additive white Gaussian noise (AWGN) and block fading channels, the multiple-access relay system with optimized profiles exhibits significant performance gains over that employing the code profile optimized for either the single-user AWGN channel or the 2-user multiple-access channel.