Multiple user channel capacity analysis of code-division multiple access system based on space-time block coding

Considering the uplink of the multiuser STBC system, a joint detection algorithm is applied at the base station in order to reduce the design complexity of mobile station. In the frequency selective fading channels, the performance of conventional DS-CDMA system suffers from multiple-access interference and intersymbol interference caused by multipath propagation. To cope with multipath channels while still benefiting from the space-multipath diversity, a new air interface that combines STBC with SC-CDMA is proposed. The expressions between the transmitter and receiver of the system are deduced in detail. The vector model between the transmitter and receiver is established. Simulation results show that the system could reach the maximum spatial diversity gains with single user and single path. When the channel has two paths, although the full spatial multipath diversity gains cannot be achieved, higher diversity gains are available. When there are multiuser activated under the frequency selective fading channels, multi antennas at the receiver can help to achieve the diversity gains as same as single path.