Relay selection in full-duplex energy-harvesting two-way relay networks

In this paper, we investigate the relay selection (RS) problem in full-duplex (FD) two-way relay networks, where the relays are wirelessly powered by harvesting a portion of the received signal power from the sources. To the best of the authors' knowledge, this is the first investigation of FD two-way relays with simultaneous wireless and information transfer capabilities. For each relay, we prove the quasi convexity of the power splitting (PS) factor optimization, and obtain the optimal PS factor in terms of the outage probability by linear search. Both single relay selection (SRS) and general relay selection (GRS) without the limit on the number of cooperating relays are investigated and the corresponding RS methods are proposed. Since the optimal GRS problem is computationally intractable with exponential complexity, we propose several low-complexity heuristic GRS methods based on various relay ordering and greedy selection criteria. Simulations indicate that the proposed GRS methods perform better than the SRS methods and achieve very similar performance compared with the optimal RS method achieved by exhaustive search but with dramatically reduced complexity.