Performance and Optimization of Two-way Relaying Under Nakagami-m Fading

This paper studies the performance of a two-way relay-based communication system with opportunistic relay selection in Nakagami-m fading environment. The two source nodes, using different modulation schemes for transmission, are unable to exchange data in direct line-of-sight and proceed via relay terminals. A "best relay", chosen by means of opportunistic selection, combines the received signals in a way that allows both sources to decode it. We provide a closed-form expression for the probability density function of the link between the "selected" best relay and each source node, and use this result to derive the average symbol error probability in closed-form. This result is further approximated for the higher signal-to-noise ratio regions and used to provide closed-form expressions for the optimized power allocated to each node involved in the communication process. We asset our formulae with numerical results and interpretations to complete this work.