Fading Correlation Analysis in MIMO-OFDM Troposcatter Communications: Space, Frequency, Angle and Space-Frequency Diversity

The capacity gain of MIMO systems significantly depends on the fading correlation between antennas, and there is no analytical study which considers the fading correlation in the troposcatter communications. In this paper, we develop an analytical model, ring scatter model (RSM), to derive the fading correlation in the troposcatter systems as a function of spatial, frequency and angular separations for the first time in the literature. In addition, we compare the effects of the diversity techniques that are suitable for troposcatter communications: space, frequency, angle and space-frequency diversity techniques by deriving the distribution of their achievable data rates with transmit beam-forming. To this end, we extend our previously introduced troposcatter channel model [1] for the implementation of MIMO-OFDM and the diversity techniques.