Opportunistic Interference Projection in Cognitive MIMO Radio with Multiuser Diversity

Opportunistic interference projection (OIP) is a cognitive radio (CR) scheme thats enables secondary users to co-exist with the licensed primary users in a spectrum sharing system and thereby improving the spectrum utilization. The presence of multiple cognitive terminals offer multiuser diversity gain, which enhances the throughput performance. Interference projection techniques works well when the transmitters have perfect channel knowledge, which is quite unrealistic assumption in real-time. In this paper, we investigate the benefits of multiuser diversity and the application of limited feedback precoding schemes for CR network with a primary and multiple cognitive MIMO links. The primary receiver feedbacks the codebook index corresponding to the precoding matrix to the cognitive transmitter through a finite rate feedback. The cognitive receiver involves in the selection of the cognitive transmitter that maximizes the system throughput performance. We present numerical simulation results of the data rate achieved in both the links for various system settings.