Design Aspects of Multiantenna CDMA Systems with Random Sequences

摘要

The use of multiple antennas at the transmitter and the receiver is considered for the uplink of a CDMA system. The spectral efficiency of the system is calculated when the receiver uses the minimum-mean squared error (MMSE) detector or the matched-filter detector. The spreading sequences are assumed to be random across the users, but could be dependent across the transmit antennas of each user. We consider the extreme cases of using the same sequence across the antennas, and using independent sequences. Analytical results are obtained for all cases in the large system asymptote of the number of users and the processing gain going to infinity with their ratio fixed. The results are compared with finite system simulations, and are also used to provide useful design guidelines for the choice of the detector, the sequence design across transmit antennas and the number of transmit antennas.