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In this paper, we analyze the role of CSIT on the fundamental performance tradeoff for a MISO/SIMO link. Defining CSIT quality order as alpha = - log sigma2 Deltah / log SNR, we showed that using rate adaptation, one can achieve an average diversity order of d macr(alpha, r macr) = (1 + alpha - r macr)n where n is the number of transmit or receive antennas, r macr is the average multiplexing gain and alpha is the CSIT quality. We also showed that this diversity order is optimal for r macr isin [0.1 - alpha] and alpha < 1. The relationship suggests that imperfect CSIT can also provide additional diversity order and interpret the CSIT quality order as the maximum achievable spatial multiplexing gain with n diversity order.