The goal for the next generation mobile communication systems based on CDMA is to integraterna wide variety of communication services such as high speed data, video and multimedia trafficrnas well as voice signals. To effect these services, high rate data transmission and receptionrntechniques are required.rnAs demands for communication services increase, there is considerable economic benefit inrnimproving the spectral efficiency of the communication system. One of the proposed approachesrnfor these high data rate and spectrally efficient transmission in CDMA systems is space-timerncoding. The use of space-time coding techniques in CDMA systems increases multiuserrninterference. The effect of multiple access interference can be mitigated by using multiuserrnreceivers. Multiuser receivers in STC CDMA systems have been shown to provide significantrnimprovements in spectral efficiency. However, despite the great promises, these receivers havernnot been widely deployed in commercial communication systems. This lack of commercialrninterest is partly because of issues related to receiver complexity.rnThus using analysis, reasonable approximations and simulation, this work attempts to realize arnlower complexity multiuser receiver for STTC DS-CDMA systems. The complexity is reducedrnby dividing the users into groups having smaller trellises. The simulation results show that thernproposed receiver performs close to the optimal receiver even at high cross correlations of thernspreading sequences with a reduced complexity.rnKeywords: CDMA, Spreading Sequences, Space-Time Coding, Fading Channels, MultiplernAccess Interference multiuser detection