Energy-efficient power allocation with spectrum sensing in cognitive radio networks

Cognitive radio (CR) has emerged as a demanding concept for exploiting the unused spectrum bands of primary users when these spectrum bands are not currently being used. The spectrum sensing techniques in CR networks increase the energy consumption while improving the throughput of the networks, and therefore the energy saving in CR networks has attracted a lot of attention from both the government and the network operators. In this paper, we investigate the energy-efficient transmit power allocation scheme in CR networks. The optimization problem is formulated as a ratio of the spectral efficiency (SE) to the total energy consumption utilized in signal transmission and spectrum sensing under a total power constraint. Next, we propose an optimal energy-efficient power allocation scheme which iteratively improve the efficiency and finally reach the optimal solution. In addition, an expression for optimal solution is derived through dual-decomposition. Simulation results are used to show the performance of the proposed transmit power allocation scheme which can greatly improve energy efficiency (EE).