Energy-efficient power allocation for cooperative relaying Cognitive Radio networks

In this paper, we study the power allocation in Orthogonal Frequency Division Multiplexing (OFDM)-based Cognitive Radio (CR) networks with cooperative relay. Since the energy consumption is growing at a staggering rate, green radio, which puts emphasis on the energy-efficiency (EE) in wireless networks, is becoming increasingly important. Therefore, we try to maximize the EE of a relaying CR system, under the consideration of many practical limitations, such as transmission power budget, interference threshold of the primary users and the traffic demand. We first convert the formulated problem into a convex optimization one via its hypogragh form, which can be solved by the barrier method. By exploiting the special structure of the formulated convex optimization problem, we further speed up the computation of Newton step during the barrier method, significantly reducing the complexity of the algorithm. Numerical results validate that our proposal can exploit the overall EE of the CR system, while the algorithm converges efficiently and stably.