Investigation of diversity and beamforming techniques for UMTS high speed downlink packet access

This paper deals with the high speed downlink packet access (HSDPA) in UMTS/FDD system. The transmit diversity and beamforming techniques are focused on, namely space time transmit diversity (STTD), closed loop mode 1 transmit diversity, conventional beamforming and closed loop beamforming with 2 transmit antennas. The link level system performance of the various methods is investigated and compared for the fading environment. At low user speeds, closed loop transmit diversity turns out to be superior. STTD has the lowest system complexity and achieves an acceptable performance at high SNR. Both beamforming schemes are the good solutions for high speed mobile terminal at low SNR.