An adaptive antenna method for improving downlink performance of CDMA base stations

The downlink performance of a beamforming CDMA base station deteriorates significantly in environments with large angular spread of the impinging signals. This problem can be alleviated by exploiting angular diversity. The aim of this work was to study a multibeam approach in the downlink. Both downlink and uplink simulations were carried out for channel models with flat and frequency selective fading. The co-channel interference was assumed as spatially and temporally white. The results show that when employing two transmitting beams the downlink performance improves by 4-8 dB at a bit error rate of 10^-2 compared to the reference case of a single transmitting beam. It was also found that the more antennas the array has the more important is the downlink diversity scheme