Interference-aware joint user selection and quantised power control schemes for uplink cognitive multiple-input multiple-output system

The authors investigate the interference-aware joint secondary user (SU) selection/scheduling and quantised power control (JSUS-QPC) schemes for the uplink communication in the cognitive multiple-input multiple-output (MIMO) system. The main objective of JSUS-QPC is to maximise the sum-rate capacity of the cognitive MIMO uplink communication system under the constraint that the interference to the primary user (PU) is below a specified level. The computational complexity of finding an optimal JSUS-QPC scheme by exhaustive search grows exponentially with the number of users and power levels. The authors also show that the JSUS-QPC is a non-deterministic polynomial-time hard problem and present two low-complexity algorithms for JSUS-QPC problem. Also, the effect of different system parameters (e.g. interference threshold level, the number of PUs, the number of SUs, the number of quantised power levels, etc.) on the performance of the proposed algorithms is examined. The proposed algorithms have low computational complexity, and their effectiveness is verified through simulation results.