Energy-efficient resource allocation in wireless powered CCRNs with simultaneous wireless information and power transfer

Abstract

In this paper, we study the optimal energy efficiency resource allocation for simultaneous wireless information and power transfer (SWIPT) in cooperative cognitive radio networks (CCRNs). The optimal design attempts to deploy each secondary receiver (SR) to harvest the energy and to use the signal received from the secondary transmitter (ST) to decode information. For the information transmission, a traditional multiple access scheme, namely, time division multiple access (TDMA) is addressed. For the TDMA-based information transmission, the users are scheduled in non-overlapping time slots to decode information. To tackle the design with the above scenarios, an optimization problem is formulated to maximize the energy efficiency of the secondary system constrained with the uncertainty of channel state information (CSI). To solve this non-convex problem, nonlinear fractional programming is utilized to transform the objective function into a subtractive form. The nonlinear fractional programming is also used to decompose the problem into two convex subproblems, and the probability constraints of signal to interference plus noise ratio (SINR) are converted into the deterministic ones using integral transformation. A joint optimal time and power allocation (JOTPA) iterative algorithm is proposed to determine the optimum of original non-convex problem. Simulation results have verified the effectiveness of the proposed resource allocation algorithm.