Wigner-ville distribution MVDR beamforming scheme for interference-tolerant cognitive radio network

Abstract

Interference-tolerant cognitive radio (CR) networks are emerging as a long-term solution to CR spectrum-sharing between licensed primary users (PUs) and unlicensed secondary users (SUs). Moreover, the networks allow PUs and SUs to coexist in so far as the interference at PU receivers is below an acceptable threshold defined as interference temperature. In this paper, we consider the design of a robust nonstationary minimum-variance distortionless response (MVDR) beamformer. The beamformer is employed in a simple CR network, comprised of a fixed base station with multiple antennas and a mobile CR user (mCRU) with a single antenna, as an interference management technique. The beamformer which is located at the base station determines the direction-of-arrival (DOA) of uplink time-reversal communication from the mCRU to the base station. The performance of the proposed robust nonstationary MVDR beamformer is demonstrated via simulation studies.