Minimum SINR maximization in the downlink of cognitive radio networks

In this paper, we study the problem of minimum signal-to-interference-plus-noise ratio (SINR) maximization in the downlink of a cognitive radio (CR) network. Subject to quality of service (QoS) constraints of all users and maximum transmission power constraints, an optimization scheme, employs genetic algorithm, is proposed to jointly calculate the complex weight vectors and downlink power allocations. The proposed scheme is applied in two different scenarios. In one scenario, the primary network cooperates in the power allocation and beamforming algorithm and adjusts its transmission power follow the instruction from CR network. In the other scenario, the primary network does not participate in the optimization process. The performance of the proposed scheme is investigated through numerical results.