Achievable Rate Region Bounds and Resource Allocation for Wireless Powered Two Way Relay Networks

Abstract

This paper investigates the wireless powered two way relay network (WPTWRN), where two single-antenna users and one single-antenna relay firstly harvest energy from signals emitted by a multi-antenna power beacon (PB) and then two users exchange information with the help of the relay by using their harvested energies.In order to improve the energy transfer efficiency, energy beamforming at the PB is deployed.For such a network, to explore the performance limit of the presented WPTWRN, an optimization problem is formulated to obtain the achievable rate region bounds by jointly optimizing the time allocation and energy beamforming design.As the optimization problem is non-convex, it is first transformed to be a convex problem by using variable substitutions and semidefinite relaxation (SDR) and then solve it efficiently.It is proved that the proposed method achieves the global optimum.Simulation results show that the achievable rate region of the presented WPTWRN architecture outperforms that of wireless powered one way relay network architecture.Results also show that the relay location has significant impact on achievable rate region of the WPTWRN.