Power Control in Full Duplex Underlay Cognitive Radio Networks: A Control Theoretic Approach

Both cognitive radio (CR) and full duplex transmissions are both effective means to enhance spectrum efficiency and network capacity. In this paper, we investigate the problem of power control in an underlay CR network where the CR nodes are capable of full-duplex (FD) transmissions. The objective is to guarantee the required quality of service (QoS) in the form of a minimum signal-to-interference-plus-noise (SINR) ratio at each CR user and keep the interference to primary users below a prescribed threshold. We design an effective distributed power control scheme that integrates a proportional-integral-derivative (PID) controller and a power constraint mechanism to achieve the above goals. WE then develop a hybrid scheme that can switch between FD and half duplex modes. The proposed schemes are validated with extensive simulations.