Low-complexity joint beamforming and power control for SINR balancing and number of antenna considerations in cognitive radio

The SINR balancing problem involving joint beamforming and power control is considered in the cognitive radio network, wherein the single-input multi-output multiple access channels are assumed. Subject to two sets of constraints: the interference temperature constraints of primary users and the peak transmission power constraints of cognitive users, a low-complexity joint beamforming and power control algorithm called semi-decoupled multi-constraint power allocation with constraints preselection (SDMCPA-CP) for SINR balancing is proposed. Compared with the existing algorithm, the proposed SDMCPA-CP can reduce the number of matrix inversions and matrix eigenvalue decompositions significantly, while still provide the optimal balanced SINR level for all the cognitive users. In addition, based on SDMCPA-CP, a two-phase search (TPS) algorithm for the number of antenna is further presented. With TPS algorithm, the minimal number of antenna which satisfies the above two sets of constraints as well as the QoS requirements of all the CUs could be found fast.