Performance analysis of an antenna array-based CDMA receiver using multi-user detection in a multipath channel

We consider incorporating an adaptive antenna array into the decorrelating multi-user detector to effectively increase the system capacity in a multipath fading channel. Capacity improvement is due to beamforming gain; spatial diversity gain (assuming large angle spread); and the decorrelating effect. The receiver consists of a front-end beamformer for every user in the cell and has knowledge of all users´ signature sequences. The beamformer uses the existing code-filtering approach to estimate the desired user channel vector, enhancing its signal and reducing the co-channel interference from other directions. The average uncoded bit error rate (BER) as a function of the number of in-beam active users, the average antenna signal-to-noise ratio (SNR), and the number of receiving antennas is examined in a multipath Rayleigh fading channel. Analysis shows an increase in system capacity proportional to the number of antennas