Research On Coordinated Beamforming Based On LTE MIMO-OFDM System

In LTE or LTE-A systems, the coordinated beamforming technique could reducethe correlation about the useful channels of users, so that the users could easily receiveand detect the useful information, and remove the interference from other downlinksignals. For multi-cell system, the coordinated beamforming could improve theperformance of cell-edge users who suffer from significant inter-cell interference (ICI),it has latest cellular communication standard. Therefore, this thesis shall mainly studythe coordinated beamforming technique about inner-cell and inter-cell system.Firstly, for perfect feedback, this thesis proposes a new user selection algorithm forinter-cell coordinated beamforming, which utilize the parallelity between the inter-cellinterfering channels of users, and then we analyze and prove the proposed algorithmowns better performance than former algorithm in theory and simulation.Secondly, for limited feedback, in order to reduce the complexity of beamformingvector computation at base station and users, the thesis provides a new method usingprojective arithmetic operators to search the appropriate codeword. Further more, wededuce how much it reduces the computation. Simulation results indicate that theproposed method has distinct advantage comparing the conventional method.Finally, on the basis of characteristics about MIMO system and coordinatedbeamforming, we construct a virtual MU-MIMO system model, and present a schemewhich could achieve multi-cell coordinated beamforming with limited feedback. In thescheme, each BS utilizes SLNR to choose appropriate codeword for users incorresponding cell. The simulation results prove this scheme can raise the throughputper user, and restrain the ICI effectually.