Dynamic spectrum sharing and user scheduling for CR-MIMO system based on interference alignment

In this paper an interference alignment (IA) based dynamic spectrum sharing and user scheduling scheme for cognitive radio (CR) multi-input multi-output (MIMO) uplink system with multiple secondary users is proposed. The difference of spatial transmission performance originating from various channel matrices is exploited to implement appropriate user scheduling. Then by IA processing, cognitive transmission is confined to subspace orthogonal to the authorized signal subspace. Consequently, opportunistic interference-free sharing of idle spatial subchannel(s) licensed to the primary is achieved. Simulation results show that the proposed strategy could utilize idle spatial channel resource effectively and obtain multiuser diversity gain. On the premise that primary transmission is protected from disturbing, cognitive throughput is significantly improved.