Optimal power control in interference-limited cognitive radio networks

Power control for multiple cognitive radios is investigated for broadcast service under the coverage of primary base station. Multiple secondary broadcasting base stations are assumed to operate in the same frequency band as that of primary system. However, the performance of the primary users can be degraded due to the interference from secondary base stations. Therefore, to cope with this problem, a new interference metric is considered to account for the impact on the broadcast service of the primary system. This new interference metric focuses on the percentage of interfered primary receivers. Furthermore, we consider the broadcast service of secondary receivers to be optimized for the utility function. To maximize the total utility of coexisting secondary receivers, an iterative method is proposed for the optimal power allocation. Simulation results show that the proposed algorithm converges to the optimal power level while guaranteeing interference level to the primary system.