Impact of multipath clustering on correlation and MIMO system performance in Rayleigh fading channels

Abstract

This thesis extends single cluster of multipath channel model to multi-cluster one. This multi-cluster channel model, which is more accurate than single cluster, has a profound effect on MIMO channel correlation and system performances. Based on this multi-cluster channel model, closed-form expressions of channel correlation are derived. The results using multi-cluster channel model agree with those using single cluster one. The results of the derived equations are also in full agreement with the results obtained from Monte-Carlo simulations. Using two-cluster channel model, the MIMO channel correlation coefficient has an oscillatory behavior with respect to the antenna spacing. Besides the angular spread and mean angle of arrival of the 2nd cluster, the power allocation has a significant effect on MIMO channel correlation. Similar to the behavior of channel correlation, both the MIMO channel capacity and diversity gain also oscillates with respect to the antenna spacing because of the 2nd cluster. It is also demonstrated that it is possible to orient the antenna array in such a way that the correlation is minimized and the maximum capacity can be achieved provided that the minimum element spacing is respected.