Transmission Mechanism and Performance Analysis of Multiuser Opportunistic Beamforming in Rayleigh and Rician Fading Channels

This paper investigates the performances of multiuser downlink opportunistic beamforming (OBF) systems in both Rayleigh and Rician fading channels with the limited feedback information. The statistical characteristics of the equivalent channels show how OBF affects the channel gain. The optimal OBF weight is derived to achieve the maximum capacity. Moreover, the relationship between the capacity and feedback information is analyzed in details. In order to meet different quality of service requirements, we propose two transmission mechanisms that are, respectively, based on maximum-capacity and fairness criterions. Since the closed-form expression of the bit error ratio (BER) is hard to obtain, the upper and lower bounds of BER are derived to approximate the theoretical values. Finally, numerical results are presented to validate our analysis and provide further insights.