| In the early ages of wireless communication, the value of multiple antenna systems as a means of improving communication have recognized by researchers. With the rapid development of wireless communication technology, regardless of the transmitter or the receiver, multiple antennas technology has been widely used. Driven by efforts in signal and information theory, the Multiple-Input Multiple-Output (MIMO) systems was a key milestone achieved in the mid-1990s. With the development of MIMO technology, beamforming technology was utilized in mass-market commercial. Multiuser diversity is a form of diversity inherent in a wireless network, provided by independent time-varying channels across the different users. The diversity benefit is exploited by tracking the channel fluctuations of the users and scheduling transmissions to users when their instantaneous channel quality is near the peak. The opprotunistic beamforming technology using multiple antennas to arouse huge and fast channel fluctuations to make the multiuser diversity exploited. The key point of user scheduling is the fluctuations that multiple antennas caused. In the downlink wireless communication systems, opportunistic beamforming is a practical and widely used technique for user-scheduling. The critical element of the opportunistic beamforming is the beamforming. There are many studies focus on the channel fluctuations but put little eyes on the beam’s angle.In this thesis, we investigate system performance if the beam angle changes in a sweeping way. The thesis considers the scheme under cellular network systems and put more eyes on the slow fading channel states. The base stations equipped with smart antennas which generate beams according to the defined algorithm. An angle sweeping scheme is proposed to change the beam angle from0to2n and bring fluctuations to the channel which make the scheduling better. By combining memory function, the proposed scheme is more practical and suitable for the few user circumstance. |
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