Performance Comparison of Space-Time Coded MIMO-OFDM Systems Using Different Wideband MIMO Channel Models

Abstract

This paper investigates the performance of multiple- input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems using different wideband MIMO channel models. The considered MIMO channel models are based on the geometrical elliptical model and the geometrical one-ring model. The spatial correlation effects due to the limited antenna spacings and the Doppler effect caused by the movement of the receiver are studied separately. It is shown that increasing the antenna spacings leads to a higher diversity gain. The relevant range of the antenna spacings that has a strong influence on the system performance is obtained through simulations. When the antenna spacings exceed the determined range, then the diversity gain does not increase significantly. Moreover, to achieve the same system performance, the MIMO-OFDM system employing the one-ring model requires larger antenna spacings than using the elliptical channel model. Furthermore, the influence of the maximum Doppler frequency has been studied under perfect and imperfect channel state information (CSI). It is demonstrated that system performance degradations occur if the maximum Doppler frequency increases, especially in case of imperfect CSI.