Energy-Efficient Resource Allocation for Cooperative Wireless Powered Cellular Networks

This paper investigates energy-efficient resource allocation for cooperative wireless powered cellular networks (WPCNs), where the cellular and device-to-device (D2D) users first harvest energy from the HAP and then the D2D user consumes a portion of power to help the cell-edge cellular user relay the data in exchange for some time from cellular user for D2D communications. Under the proposed cooperation scheme, we formulate an energy efficiency (EE) maximization problem. The energy beamforming vector, time assignment and power allocation are jointly optimized under the transmission rate requirements and available energy constraints of both D2D and cellular users. Based on the fractional programming theory and semi-definite relaxation (SDR) method, we transform the originally non-convex EE maximization problem into a standard convex problem. This allows us to design efficient resource allocation algorithm for achieving optimal solution. Extensive simulation results are provided to show the convergence rate of the proposed iterative algorithm and to demonstrate the EE improved by the proposed system than that of two baseline systems.