Relay Selection and Throughput Maximization for Full Duplex Wireless Powered Cooperative Communication Networks

Cooperative communication using energy harvesting (EH) nodes promises significant improvement in network throughput, coverage, and reliability. This work studies a full-duplex (FD) wireless powered cooperative communication network (WPCCN), in which the users communicate to a hybrid access point (HAP) via decode-and-forward (DF) EH relay nodes. We present an optimization framework for the relay selection problem with an objective of maximizing the sum throughput of the FD-WPCCN, for the first time in the literature. The formulated optimization problem is a mixed integer non-linear programming problem (MINLP), which is difficult to solve for global optimal solution. As a solution strategy, we first analyze the problem for a given relay allocation and prove that it is a convex problem. We solve the problem for the optimal solution by using the Karush-Kuhn-Tucker conditions. Then, for the relay selection problem, we present a polynomial time heuristic algorithm based on the allocation of relay with the best channel conditions to each user. Through extensive simulations, we show that the proposed algorithm performs close to the optimal solution for various network parameters such as different HAP transmission power values, network sizes, and initial battery level of the nodes. We observe that the sum throughput of the network can be increased significantly by using a proper relay selection technique.