A relay selection method for bidirectional wireless cooperative networks based on the log-likelihood ratio

Applying network coding to a wireless cooperative communication network always proves beneficial, in terms of gains in spatial diversity, improved coverage and channel capacity. In this paper, a relay-selection method for a bidirectional (two-way) wireless cooperative communication system is proposed. A single best relay node or set of relay nodes are selected to jointly forward the combined data streams from two users. The method is based on the value of the log-likelihood ratio of the received signal at each relay node in the system. Performance is measured in terms of bit error rate (BER) curves and outage probability curves. A comparison with opportunistic relaying is carried out.