Layered Source-Channel Coding over Two-Way Relay Networks

In this paper, we study the performances of various layered source-channel coding schemes over two-way relay networks, where the sources are coded into different layers and transmitted by progressive coding or superposition coding. The two-way relay network employs multiple-access-broadcast or time- division-broadcast protocol, and the relay uses decode-and-forward (DF) protocol. We first derive the optimal distortion exponents of different schemes at high signal-to-noise ratios (SNRs). Fast resource allocation algorithms are then developed to optimize the expected distortion of the source at finite SNRs. Simulation results show that layered coding achieves better performance than single rate coding, and the proposed fast resource allocation scheme is near-optimal.