Research On MIMO Space-Time Correlation And Antenna Array Configurations

The main focus of this research is to investigate the performance of multiple-input and multiple-output (MIMO) antenna arrays systems including MIMO space-time correlation and antenna array configurations. To investigate space-time MIMO system, we describe a statistical-based vector channel model for uniform linear arrays(UCA) and uniform circular arrays(ULA) and developed a statistical time-varying multipath MIMO channel model to be used in our research firstly. Then we derived generalized formulas for spatial correlation and show that it provides a good approximation for spatial correlation for four very different angular energy distributions: a Gaussian angular distribution, a Gaussian spatial distribution, a uniform angular distribution and a Laplace angular distribution. In the analytical results, it is found that the standard deviation of the angular energy distribution or the angle spread is the dominating factor for the determining correlation. Based on these results, the analytical expression for the MIMO channel space-time fading correlation for uniform circular array and uniform linear array is derived in a Rayleigh fading channel. The MIMO channel space-time fading correlation are evaluated for both uplink and downlink communication. Then we investigate the impact of fading correlation on symbol error rate (SER) performance of M-ray phase shift keying (MPSK) with maximal ratio combining(MRC) and present a comparison between the SER performance of UCA and ULA. The performance evaluation uses the expression for the SER of MPSK, then averages it over the density function for the combined symbol signal to noise ratio (SNR). The analytical SER is derived as a function of the spatial fading correlation for the two antenna array configurations. Results show that UCA outperforms the ULA on average for low-to-moderate angle spread. Finally, we evaluated the information-theoretic channel capacity of a MIMO channel with both UCA and ULA antenna configurations. The results suggest that a (ULA,UCA) MIMO antenna configuration may be the preferred choice for higher channel capacity in mobile environments.