Performance of coherent adaptive antenna array beamforming combined with MRC diversity techniques in W-CDMA reverse link

This paper presents coherent adaptive antenna array beamforming (CAAA-BF) combined with maximal ratio combining (MRC) diversity techniques (space diversity, SD, or polarization diversity, PD) and evaluates the interference suppression effect of these methods under multipath fading in the W-CDMA reverse link. Computer simulation results show that even when the number of active users is 150 (note that the capacity normalized by the processing gain, Pg, is 78%), the required transmit signal energy-per-bit-to-background-noise power spectrum density ratio (E_b/N₀) at the average block error rate (BLER) of 10^-2 with CAAA-BF with 2-branch SD reception, i.e., 4 antennas per branch, is decreased by approximately 1.4 dB compared to that with CAAA-BF using 8 antennas. These results indicate that by combining CAAA-BF with diversity techniques, although the interference suppression effect is slightly decreased compared to that with CAAA-BF using the identical number of antennas in an interference-limited channel, due to the broadening beam width, there is a significant additional space diversity effect especially when the number of resolved paths is small