Transmit antenna selection protocols in random cognitive networks under impact of hardware impairments

In this paper, we evaluate performances of various transmit antenna selection (TAS) protocols in underlay cognitive radio network under impact of hardware impairments. In particular, a secondary base station (SB) selects one of available antennas to transmit its data to a secondary user (SU) that randomly appears in radio range of the SB. In the first proposed scheme (named RAND), the SB randomly selects one antenna to serve the SU. In the second proposed method (named MAXP), the antenna with maximum transmit power will be used to transmit the data. In the third proposal scheme, an optimal TAS method is proposed to maximize the instantaneous signal-to-noise ratio (SNR) of the SB-SU links. For performance evaluation, we derive exact and asymptotic closed-form expressions of average outage probability (AOP) for the proposed protocols over Rayleigh fading channel. Monte-Carlo simulations are then performed to verify the theoretical results.