Robust Beamforming and Power Control for Multiuser Cognitive Radio Network

In multiuser cognitive radio (CR) network, we address the problem of joint transmit beamforming (BF) and power control (PC) for secondary users (SUs) when they are allowed to transmit simultaneously with primary users (PUs). The objective is to optimize the network sum rate under the interference constraints of PUs. Due to lack of cooperation among different nodes in the network, channel uncertainty is considered. In a worst case philosophy, a closed-form worst-case expression is derived, with which the uncertainty optimization problem is transformed into a certain one. Second-order cone programming approximation (SOCPA) method is proposed as a robust algorithm. Typical network models are approximated to second-order cone programming problems and solved by interior-point method. Finally the network sum rates for different PU and SU numbers are assessed for both certainty and uncertainty channel models by simulation.