We discuss downlink beamforming methods in consideration of a terminal having a joint detector function for space division multiple access (SDMA) in both a multi-input single-output (MISO) channel and a multi-input multi-output (MIMO) channel. We investigate two methods; a general beamformer, which maximizes the desired signal's power at the receiver (a transmit MRC diversity) and a null steering concept, which avoids the interference signal reaching the receiver. The computer simulation results show that the null steering concept yields better performance compared to the beam steering, even considering the joint detection at the receiver.
['Toshihiko Nishimura', 'Takeo Ohgane', 'Yasutaka Ogawa', 'Yoshiharu Doi', 'Jun Kitakado']
Downlink beamforming performance for an SDMA terminal with joint detection