Optimal Power Control and Time Allocation for Wireless-powered Relay Networks

In this letter, optimal power control and time resource allocation schemes are considered in wireless relay network, which two users communicate with each other assisted by an energy harvesting relay that gathers energy from the received signal by applying a time switching scheme and forwards the received signal by using the harvesting energy. It is focused on the optimal power control and time resource allocation for the system to cooperate the power transfer and information transmission among three nodes in Decode-and-Forward (DF) mode. Specifically, time ratios for three transmission phases are firstly investigated. Then, we proposed to formulate the power optimization problem with energy constraint. Since the transmission duration of the transmitter is not fixed, the energy constraint instead of power constraint is more reasonable to evaluate the system performance. Through some variables substitution, we demonstrate that it is a convex problem. It can be solved efficiently by convex optimization technology. Simulation results are demonstrated that the performance of the proposed algorithm outperform than the fixed and semi-fixed traditional methods.