Research On Random Beamforming

At present, people's demands of multi-media communications services increase continuously. Therefore, as a new technique, which can increase spectrum efficiency remarkably; multi-antenna technique will become the focus point in the next years. The researchs on the schedule and spatial multiplexing of MIMO system can improve the system performance as much as possible, and random beamforming discussed in this paper is just one of these researchs.In the first, this paper introduces some fundamental principle of MIMO, opportunitily beamforming and orthogonal random beamforming, and demonstrates the superior performance of orthogonal random beamforming theoretically. On the basis of this, beam number's influence on system performance is given, and some this kind techniques and their simulations would be shown later.Based on the theoretical analysis of orthogonal random beamforming, several improve methods to random beamforming are proposed. Firstly, multiple beam matrix idea is used in orthogonal random beamforming, and a new training mode is proposed to overcome the problem of long training time, which come from the multiple beam matrixes. The simulation results show this method can increase system performance when user number is large. Secondly, this paper use the second feedback in orthogonal random beamforming, Givens angles would be feedbacked to base station to change the directions of orthogonal beams. Finally, to improve the performance of MIMO system when the receiver has several antennas, a new proposal is given. This proposal can improve performance at the cost of calculated amount.At last, this paper summarizes the random beamforming and this paper's content. Moreover, some developing directions are also given.