Beamforming degradation of a W-CDMA smart antenna under FDD and MAI channel estimation errors

Abstract

A smart antenna adopts the beamforming technique to increase the signal-to-(interference plus noise) ratio (SINR) and system capacity. In this paper, the impact of two channel estimation errors - frequency-division duplex (FDD) estimation error and multiple-access interference (MAI) estimation error for the beamforming of a wide-band code-division multiple-access smart antenna - are analyzed by using the measured channel state information. Results show that for a complex conjugate beamforming, FDD estimation error will cause median degradation of less than 1 dB if the desired signal is in a line-of-sight (LOS) channel and 1-3 dB if in a non-LOS (NLOS) channel. In addition, the MAI estimation error will cause 0.3-0.5 dB degradation per interference in the LOS case and 0.5-1 dB degradation in the NLOS case