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The performance of new differential detection schemes with transmit diversity (TD) for direct-sequence code division multiple access (DS-CDMA) systems is evaluated. Two TD schemes are considered. One is the orthogonal transmit diversity (OTD) and the other is the space-time transmit diversity (STTD). To enable blind detection, the two schemes of differential encoding/decoding in combination with the minimum variance distortionless response (MVDR) receiver are proposed. Both schemes provide full spatial diversity and require no channel state information at the transmitter as well as the receiver. The performance of the proposed OTD+MV and STTD+MV transceivers are much better than that of the conventionally used OTD+MF (matched filter) and STTD+MF receivers. The STTD+MV outperforms the OTD+MV at the price of a higher receiver complexity.