Energy-Efficient Beamforming Design for User-Centric Full-Duplex Wireless Backhaul Networks

In this paper, we investigate an energy-efficient beamforming design in a user-centric full-duplex backhauling network, where simultaneous transmission and reception on the same frequency band for access and backhaul links are enabled by full-duplex access points. Specifically, multicast transmission is adopted by macro base station and cooperative transmission is adopted by access points to serve users. We first formulate an optimization problem to maximize the network energy efficiency while taking the power consumed by self-interference cancellation at full-duplex access points into consideration. This problem is formulated as a nonlinear fractional programming and is transformed into an equivalent subtractive form by Dinkelbach method. The equivalent optimization problem is still non-convex. To make it more tractable, we first adopt semidefinite relaxation to remove part of non-convexity, and then adopt the successive convex approximation method to further deal with the rest of non-convex parts, and finally propose an iterative algorithm. Simulation results demonstrate the superiority of the proposed algorithm and provide insights into the design of full-duplex backhauling network.