Efficient Integration of Cognitive Radio in a Multiuser MIMO Channel Environment

The design of energy and spectrally efficient multiuser (MU) MIMO networks is a very challenging problem with many tradeoffs to consider. In this paper we address the problem of designing energy efficient (EE) Primary Multiuser (P-MU) MIMO networks when Cognitive Radio (CR) Secondary users (SU) are being incorporated. We investigate what are the proper channel conditions for integration of the CR transceivers in a P-MU MIMO network. We aim to minimize the total consumed power with the maximum possible spectral efficiency. This paper also addresses the application of CR combined with automatic RF signal classifier (RFSC). It argues that the two applications can be complementary and the latter can support another mode of operation for CR. An SU can operate in presence of an active primary user (PU) without interfering, unlike the standard approach whereby SUs should not be activated when active PUs are sensed. OFDM is the signaling strategy of choice for the P-MU to do spectrum sharing and control interference.