Joint rate and power control using distributed algorithms in cognitie radio networks

Radio frequency spectrum is limited and highly contested, hence cognitive radio networks’ perceived ability to improve spectrum utilisation has gained much attention. Joint rate and power control is a method that can be used by unlicensed secondary users to share spectrum with licensed primary users as long as it provides QoS guarantees to both secondary and moreover to primary users. In this paper, we propose a distributed joint rate and power control algorithm for infrastructure-less cognitive radio networks in which each user adjusts their transmit power and rate of transmission by considering the QoS of both primary and secondary users. We propose a fully distributed iterative algorithm in which the aggregate transmission power for cognitive radios is calculated assuming a maximum initial data rate. If the calculated power is more than the maximum allowed power level, the data rate is reduced and power is recalculated iteratively. Simulation results show that by using the proposed approach a higher number of users can be supported while the QoS constraints for both primary and the secondary users are maintained