On the Optimal Power Allocation for Two-Way Full-Duplex AF Relay Networks

This paper investigates the optimal power allocation that maximizes the system utility for a full-duplex (FD) amplify-and-forward (AF) relaying two-way relay network (TWRN) with a rate outage and a power constraint. Both cases of an individual and a sum power constraint are considered. To formulate the corresponding optimization problem, closed-form expressions of outage probabilities are needed. With FD transceivers, the derivation of such closed-form expressions becomes too involved. Thus, approximate closed-form expressions were derived instead. The resulting optimization problem is still non-convex and difficult to solve. Via solving a series of approximate convex problems, a successive convex approximation (SCA) algorithm was proposed. Our simulation results demonstrate the proposed SCA algorithm achieves near-optimal performance and outperforms the full power allocation under the individual power constraint and uniform power allocation under the sum power constraint both in system utility and in power consumption. A tradeoff between the FD system and the half-duplex (HD) system with respect to the residual self-interference was also observed.