New differential transmission scheme with transmit diversity for DS-CDMA systems

This paper presents a new differential encoding scheme for direct sequence code division multiple access (DS-CDMA) systems using space-time block code with space-time transmit diversity (STTD). The proposed generalized differential encoding scheme at the transmitter and the corresponding low complexity differential decoding scheme at the receiver ensure a blind detection. The proposed transmission scheme provides full spatial diversity and requires no channel state information at the receiver. Comparing our STTD scheme (referred to as STTD₁) with the classical STTD scheme (referred to as STTD₂) of B.M. Hochwald et al. (see IEEE J. on Selected Areas in Communications, vol.19, p.48-60, 2001) and the orthogonal transmit diversity (OTD) schemes, it is shown that STTD₁ has better performance than both STTD₂ and OTD schemes.