In this paper, we consider Rayleigh fading MIMO relay channel with channel state information at the receivers. First, we extend the previously obtained results for the ergodic capacity of uncorrelated and semi-correlated MIMO channels and derive closed-form expressions for the capacity bounds of MIMO relay channel. Next, we study this channel from a new point of view, maximizing coverage region for a desired transmission rate, and investigate the optimal relay location in the sense of maximizing coverage region. However, in order to overcome the mathematical complexity in desired transmission rate analysis, because of the randomness of the multiple antenna channel matrices, we evaluate this rate by using an existing exact formula and also by an approximation we find in the high signal-to-noise ratio regime. Numerical results show a perfect match between the Monte Carlo simulations and the obtained analytical closed-form expressions and also confirm the effectiveness of our approach in cooperative vehicular communication for determining optimal relay location at which the coverage region is maximum. Copyright © 2013 John Wiley & Sons, Ltd.

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