Random Beamforming Based User Scheduling for Downlink of Multiple Antennas System

Random beamforming has been proved to be an effective way to utilize spatial resource for downlink of multiuser scheduling system. The basic idea is utilization of multiple transmit antennas to artificially create larger channel fluctuations among different users. These fluctuations can then be exploited by a smart user scheduler to enhance the system performance. However, existing random beamforming schemes haven´t aggressively explored the available spatial resource in a proper way. This paper presents two enhanced random beamforming schemes where multiple random beams are always generated and shared by multiple users. The number of utilized random beams (equal to number of scheduled users here) is either flexible or adaptive according to different forms of feedback information. Compared with existing schemes, our proposed methods can improve the system performance significantly with a bit more feedback information.