Experimental comparison of precoding schemes for CR-MIMO systems for interference avoidance

In this paper we have studied precoding schemes for cognitive radio multiple input multiple output (CR-MIMO) system which coexist with a primary time division duplexing system. We have proposed two robust methods in enhancing the existing sensing projection based scheme (SP-Based precoding scheme). The first proposed scheme is the full projection based precoding scheme (FP-Based precoding). In this scheme, the Cognitive radio transmission is fully projected into a calculated null space of the interference channel. This scheme possesses the ability to increase the CR throughput without causing interference to the primary network. The scheme has the ability to increase the CR throughput without causing interference to the primary network. In the second scheme, the CR transmission is projected into a subspace area which partially covers the null space of the interference channel. This scheme however further improves the CR-throughput within the tolerance level of the primary system. The results presented shows that proposed schemes performance overwhelms that of the existing SP-Based precoding scheme.