Two suboptimal algorithms for downlink beamforming in FDD DS-CDMA mobile radio

Abstract

Two suboptimal algorithms are proposed for downlink beamforming in FDD DS-CDMA mobile radio by using uplink beamforming weights. One is a null-constrained method, which maintains the same null positions for both uplink and downlink beam patterns; the other is a frequency-calibrated method which constrains the same main beam positions for both patterns. We also evaluate the multicell downlink capacity of DS-CDMA systems using per-user-per-weight beamforming scheme. Outer cell interference is modeled as an AWGN process whose variance is proportional to the average intracell total tranmitted power. Computer simulations are given to compare the single cell and multicell capacities using different downlink beamforming weight generation algorithms.