Energy-Efficient Resource Allocation in Cellular Network with Ambient RF Energy Harvesting

Simultaneous wireless information and power transfer is an innovative way to provide electrical energy for user equipments. However, most previous works mainly focus on energy harvesting over a relatively narrow frequency range. Due to small energy harvested by the users, the practical applications are usually limited to low power devices. In this paper, an energy-efficient uplink resource allocation problem is investigated in a cellular network with ambient radio frequency (RF) energy harvesting. In order to obtain sufficient energy, a broadband rectenna is adopted to harvest ambient RF energy over six frequency bands at the same time. From the viewpoint of service arrival in the ambient transmitter, a new energy arrival model is presented. The problem of sub-carrier and power allocation is formulated as a mixed-integer nonlinear programming problem. The objective is to maximize the energy efficiency while satisfying the energy causality and the total data rate requirement. In order to reduce the computational complexity, a suboptimal solution is derived by employing a quantum-behaved particle swarm optimization (QPSO) algorithm. Simulation results show that the QPSO method has higher energy efficiency than a conventional particle swarm optimization approach.