Two-dimensional adaptive beamforming in DS-CDMA communication with local scattering channels

Since the antenna array at base station is typically mounted on the roof of a high building, the mobile users are not located at the same level as the antenna array. As the mobile users near the base station, a two-dimensional (2-D) array is usually required for effective adaptive beamforming, especially for sources with the same azimuth angles but different elevation angles with respect to the antenna array. In direct sequence code-division multiple access (DS-CDMA) communication, different local scatterers in the vicinity of the mobile sources cause angular spread of radiating signal as seen from a base station antenna array. The multipath propagation from coherent local scatterers will result in a steering vector which is not composed of arriving angles of original radiating sources alone. Applying first-order Taylor expansion to the array steering vector with local scattering, we provide a theoretical solution for a 2-D generalized plane-type array manifold (GPAM). Computer simulations demonstrate the effectiveness of the proposed 2-D adaptive beamforming in DS-CDMA communication with local scattering channels.