Research On Hybrid Beamforming Technique In Rician Channel

For the next generation indoor high data rate wireless communication system, the frequency band around the frequency of 60GHz is believed to be an ideal selection. The transmission property of such a wireless communication channel is supposed to be following Rician model. Adaptive antenna array can be employed to significantly improve its transmission performance.This thesis mainly researches on a hybrid algorithm for antenna beamforming which combines the radio frequency phase-shifting and baseband signal weighting. The main contributions of the thesis are summarized as follows.(1) Aiming at the property of Rician channel, the thesis proposes a hybrid beamforming algorithm based on phased antenna array combined with baseband signal weighting. It can reduce the number of baseband weights by using the phase shifters of phased antenna array so as to reduce the complexity of computation and equipment, so that it appears to be very effective economically. Furthermore, an optimization algorithm is employed to design the baseband weights, which can efficiently suppress the interference between multi-users and improve the system performance.(2) Considering the problem of that there often exists rather big deviation in estimation or parameter representation of channel in practical application, the thesis proposes a robust hybrid beamforming algorithm for the two cases such as Light of Sight (LoS) error or Non Light of Sight (NLoS) error. It can improve the transmission performance, to make the system meet the practical requirement when existing rather big error in channel representation.(3) A channel estimation method based on Linear Minimum Mean Square Error (LMMSE) is proposed in the thesis. Because of jointly designing the power allocation ratio in the channel estimation method and basedband weights in hybrid beamforming algorithm, it can guarantee the transmission quality of a system.