Performance Characterization of MIMO Channels with Hybrid Diversity

Abstract

Recent advances have demonstrated that multiple-input multiple-output (MIMO) wireless technology can achieve impressive enhancement in overall system performance. It offers spatial multiplexing and spatial diversity without increasing either the total system power nor the bandwidth and thus offering the potential for substantial improvements in channel capacity and spectral efficiency. However, the high dependence of its channel capacity on the correlation between antenna elements represents the main drawback of MIMO systems. Therefore, multi-polarized antennas have been implemented in these systems to reduce the antenna correlation and realize compact devices. This article is intended for the hybrid diversity (space and polarization) performance analysis of MIMO channels in indoor environment under non-line-of-sight (NLOS) condition. It investigates the effect of inter-element spacing on the cross-polar discrimination (XPD) and co-polar ratio (CPR). In this regard, the capacity as well as bit error rate (BER) performance of hybrid MIMO system is analyzed to draw a fair comparison between it and dual polarized along with spatial diversity techniques. The simulation results show that the hybrid diversity has a middle performance between these two scenarios of system implementations. Additionally, the performance of hybrid diversity is clearly enhanced in comparison with the dual polarized condition of operation, as the separation between the antennas increases. Moreover, as a function of the antenna separation, the spatial diversity system performance is varying slower than that of hybrid diversity case.