FDD DS-CDMA downlink beamforming by modifying uplink beamforming weights

Abstract

Two new suboptimal algorithms are proposed for downlink beamforming in FDD DS-CDMA mobile radio by using uplink beamforming weights. One is null constraint (NC) method, which constrains same null positions for both uplink and downlink. The other is frequency calibration (FC) method, which constrains the same main beam positions for both links. Even though the new algorithms are simple, they may provide larger capacity enhancement as compared with the DOA methods which just direct the main beam toward the desired user.