Performance of Nth-best antenna selection diversity systems with co-channel interference and outdated channel information

In this study, the authors evaluate the performance of space diversity systems with the Nth-best antenna selection scheme in the presence of interference and outdated channel information (OC1). The Nth-best antenna selection scheme is efficient in situations where the second or even the Nth best antenna is mistakenly selected by the destination instead of the first best antenna for data reception. In this study, they first derive the cumulative distribution function (CDF) of the end-to-end (e2e) signal-to-interference plus noise ratio at the selection scheme combiner output. This CDF is then used to derive exact closed-form expressions for the e2e outage probability and symbol error probability (SEP) of the system. In the analysis, the channels of the desired user and the interferers are assumed to follow Rayleigh distribution. Furthermore, to obtain more about system insights, the performance is studied at the high signal-to-noise ratio (SNR) regime where the diversity order and coding gain are derived. Monte Carlo simulations are provided to validate the derived analytical and asymptotic expressions. Main results illustrate that with an interference power that is not scaling with SNR, the system can still achieve diversity gain when more receive antennas are used. Also, findings show that the diversity order of the system is linearly decreasing with increasing the order of the antenna, and linearly increasing with decreasing it. Furthermore, results illustrate that as the higher the correlation coefficient between the SNRs of antennas at the selection and transmission time instances, the better the achieved performance.