A Rate Balancing Technique for MIMO-Cognitive Radio Network under a Mixed QoS Requirement

We provide a rate balancing technique with mixed Quality of Services (QoS) requirement for an underlay multiple-input-multiple-output (MIMO) cognitive radio network (CRN). Specifically, we have considered an optimization criterion such that a set of SUs are required to achieve a target data rate whilst the data rates for the remaining SUs are to be balanced. This problem with a mixed QoS requirement in the broadcast channel (BC) cannot be solved directly due to a coupled structure of the transmitted covariance matrices. Hence, we solve an equivalent multiple access channel (MAC) problem using BC-MAC duality and subgradient method. An iterative algorithm is proposed to determine the transmit covariance matrices. The convergence analysis and simulation results are provided to validate the proposed algorithm.