MMSE receiver spatial sensing technique for cognitive radio networks

We propose transceiver algorithms to manage interference in cognitive radio networks where cognitive users are equipped with multiple antennas, which is referred to as spatial sensing technique. This work considers designs of precoding and decoding matrices for spatial sensing to protect a primary network from interference of the secondary network and to remove interference by primary transmissions at the secondary receiver. As an extensive work of [1], which studied a case of a zero-forcing (ZF) receiver, in this paper, we investigate a transceiver design with a minimum mean square error (MMSE) receiver. In the design with a ZF receiver, we assumed that the interference by primary transmission is perfectly removed at the secondary receiver. In this work, to further improve the performance of secondary networks, we propose using an MMSE receiver. We show that an iterative algorithm is necessary. Numerical results confirm that the design with an MMSE receiver outperforms the design with a ZF receiver.