Simulation of MIMO channel capacity with antenna polarization diversity

A simulation study of the channel capacity of a multiple-input multiple-output (MIMO) antenna system exploiting multiple polarizations is carried out. We focus on a simple yet realistic trimonopole antenna structure, taking into account all the mutual coupling and casing effects using the computational electromagnetics solver-numerical electromagnetics code. Simulation results show that, with a special transmit geometry, using the collocated trimonopole antennas at a size-constrained receiver can offer channel capacity that approaches the capacity of an uncorrelated MIMO Rayleigh channel. In addition, it is shown that the capacity increase is mainly attributed to polarization diversity instead of pattern diversity. Furthermore, we find that the mutual coupling and casing effects in the trimonopole system can actually provide a large capacity increase with less constraint on the antenna configurations than the idealized tridipole system.

I. Introduction

A PROMISING way of achieving high data rate in wireless communications is to use multiple antennas at both the transmitter and the receiver, forming a multiple-input multiple-output (MIMO) system [1], [2]. Parallel subchannels can be established between the transmitter and the receiver antennas if the fading of the transmitter–receiver pairs is uncorrelated [3]. Correlated fading can pose a serious problem, typically at the mobile handset where the spacing of antenna elements is highly constrained. Polarization diversity and pattern diversity have been exploited to decrease the signal correlation of local antennas at mobile handsets [4]. The performance of a MIMO system employing dual-polarized antennas has been investigated in [5] and [6].