MMSE reception of DS-CDMA with open-loop transmit diversity

Several transmit diversity methods have been introduced into the base-to-mobile (forward) link of third generation (3G) standards in response to a need for increased capacity. Orthogonal transmit diversity (OTD) and space-time spreading (STS) have been included in the 3GPP2 standard, while space-time transmit diversity (STTD) is part of the 3GPP standard. In this paper, the minimum mean-squared error (MMSE) receiver is developed for all three of these transmit diversity methods. Signal-to-noise ratio expressions are developed for both the MMSE receiver and the matched-filter (RAKE) receiver, and these expressions are used to compare the relative performance of the methods.