A combined antenna array and LMMSE multi-user detection DS-CDMA receiver in multipath fading channels

In this paper, a DS-CDMA receiver that combines adaptive beamforming together with a linear minimum mean square error (LMMSE) multi-user detection in a multipath fading channel is proposed and analyzed. By beamforming, the desired user´s signal is enhanced and the co-channel interference from other directions is reduced. For in-beam multiple access interference reduction; LMMSE multi-user detection is used. The average uncoded bit error rate (BER) as a function of the average antenna signal-to-noise ratio (SNR) and the number of receiving antennas are examined in a frequency selective Rayleigh fading channel. Performance comparison between LMMSE, decorrelating and parallel interference cancellation detectors have been carried out. Simulation results show an increase in system capacity and/or improving the coverage.