Joint Decision of Sensing Threshold and Power Allocation in OFDM Cognitive Radio Networks

In this work, the joint optimization of sensing threshold and power allocation strategy in orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) networks is studied. The aim is to maximize the total capacity of secondary users (SUs) while limiting the interference caused to the primary users (PUs). Taking into account the sensing errors, the total capacity of SUs is expressed as a function of the sensing threshold and SUs' transmit power. The resulting problem represents a nonconvex mixed integer non-linear programming (MINLP) optimization. Due to the high computational complexity of the MINLP problem, an equivalent simplified problem is formulated without resorting to integer variables. A computationally efficient suboptimal algorithm is proposed to address the joint optimization problem. Using the suboptimal solution as the initial point, an alternating optimization method is then employed to enhance the solution accuracy. Computer simulation results confirm the effectiveness of the proposed algorithm.