Secondary User Access Control with MassiveMIMO in Cognitive Radio Networks

We consider the problem of secondary user access control (SUAC) in cognitive radio (CR) networks with the massive multiple-input multiple-output (MIMO) technique, where a primary user (PU) equipped with a large number of antennas coexists with a number of single-antenna equipped secondary users (SUs). In SUAC design, a jamming signal is injected by a PU to degrade the spectrum sensing performance of unauthorized secondary users (UA-SUs), while maintain reliable spectrum sensing performance for authorized secondary users (A-SUs). In this paper, a minimum mean-squared error (MMSE) estimator is used to perform uplink channel estimation, and the energy detection method is used for spectrum sensing. Given the estimated channel state information (CSI), we present two optimization algorithms to minimize the jamming signal effect on A-SUs under the constraint that the jamming signal has a significant influence on the UA-SUs. The presented non-convex optimization algorithms can be effectively solved with a semidefinite relaxation (SDR) method. Simulation results show the effectiveness of the proposed SUAC method in assuring reliable spectrum sensing performance of the A-SUs and degrading the spectrum sensing performance of the UA-SUs.