WLCp1-01: Coded Cooperative Relaying with Relay Set Expansion: Coding Gain Without Bandwidth Expansion

We present a bandwidth-efficient coded cooperative relaying technique that provides a significant coding gain without requiring an increase in bandwidth relative to uncoded cooperative relaying system. The key to the technique is that the redundant bits introduced by the code are accommodated by expanding the relay set, rather than expanding the signal set as in traditional trellis coded modulation. An increase in the number of relays produces additional interference, but its effect can be suppressed by signal processing (decorrelation) and channel coding techniques to produce a positive coding gain without sacrificing data rate or expanding bandwidth. We present the optimum number of relays and the optimal code rate that minimize the end-to-end bit error probability. Additional increase in coding gain by allowing the relay nodes to decode and re-encode is analyzed.