General and efficient relay selection for two-way opportunistic amplify-and-forward relaying

Considering the most general case that each node transmits with unequal powers, an efficient relay selection scheme is proposed for the two-way amplify-and-forward (AF) relaying system, which bypasses the need for channel estimation and can be implemented by comparing the product of each relay´s local transmit power and its received pilot signalling powers from the two sources. A tight closed-form lower bound for the system outage probability is derived in Nakagami-m fading, followed by the analysis of diversity and coding gains. Simulation results are presented to corroborate analysis.