Optimal power control in cognitive radio networks under interference power constraint and quality of service constraints

Optimal Power Control in cognitive radio networks (CRNs) under interference power constraint (IPC) and quality of service (QoS) constraints is investigated in this paper. Since the sum rate maximization of cognitive users (SUs) are non-concave maximization problem, it is challenging to design an optimal power control algorithm for the SUs such that the sum rate of the SUs is maximized under the IPC and QoS constraints. In this paper, we transform the sum rate problem into an equivalent maximization problem by variable substitution. Based on the equivalent maximization problem, we prove that only at most one SU with the best effective channel gain will obtain the signal to interference plus noise ratio (SINR) larger than the QoS constraint. Based on this result, we give the optimal power control algorithm for SU in a closed-form expression. Simulation results show that the effectiveness of the proposed power control algorithm.