Secure transmission using optimal antenna selection for MIMO underlay CRN with multiple primary users

Abstract

The authors present a method of utilisation diversity combining to improve the secrecy performance of an underlay cognitive radio network (CRN) with single or multiple primary users (PUs) over Rayleigh fading environment. They consider a practical scenario where a secondary transmitter $({ST_X})$ ( S T X ) , a secondary receiver $({SR_X})$ ( S R X ) , and an eavesdropper (Eve) receiver are equipped with multiple antennas while all PUs are employed with a single antenna. The confidential information is transmitted from ${ST_X}$ S T X to ${SR_X}$ S R X under the malicious attempt of an Eve. Generalised selection combining is applied at the ${SR_X}$ S R X , and maximal ratio combining is adopted at the Eve. Depending upon the availability of the global channel state information of the main and eavesdropper's channels at ${ST_X}$ S T X , the secrecy outage performances of optimal antenna selection and sub-optimal antenna selection schemes have been examined. They derive a closed-form expression for the exact secrecy outage probability, asymptotic secrecy outage probability and intercept probability in a Rayleigh fading environment. Numerical results show that secrecy performance of the network improves with increasing the transmitting antennas while it degrades with increasing the number of PUs.