Outage probability analysis and adaptive combiner for multiuser multipolarized antenna systems

Abstract

In this paper, we characterize the performance metrics of a multiuser multipolarized antenna system in aRayleigh fading channel. We start by formulating a downlink system model that features a multiuser scenario in thepresence of additive noise and a multipolarized antenna system; this is followed by evaluation of the outage probabilityin closed form. This is done by deriving the cumulative distribution function (CDF) of the signal-to-interference-plusnoise ratio using the approach of the ratio of indefinite quadratic forms. We thereby characterize the gradient of thisCDF with respect to the combining vectors. Eventually, we obtain the optimum combining vectors by minimizing theoutage probability via interior-point optimization technique. Simulation and theoretical results of our analysis are closelymatched, which validates our analysis. Our findings suggest that the performance of the triple polarized antenna is betterthan that of the dual polarized antenna system for low signal-to-noise ratio (SNR) values in terms of outage probability;this situation, however, reverses for high SNR value.