| As the transition of the next generation mobile communication, LTE (Long TermEvolution) can improve the rate of communication effectively. it filled thetechnological gap between the3rdG and4thG. There are many researches about LTEmultiple-antenna technique to get signal gain and system performance. This paperanalyzes channel estimation and beamforming of the LTE system.The TDD-LTE (Time Division Duplex-LTE) system, with channel reciprocityfeatures, can get downlink channel information by uplink channel estimation. First, aappropriate pilot structure fit for uplink. Then use the pilot symbol received by basestation estimate channel information in pilot position. At last get the whole channelinformation by interpolation method. CSI matrix can calculate by uplink channel stateinformation (CSI), then use beamforming technology. But mainlobe interference willcause beam direction offset and sidelobe level increase. Exist method can correct beamdirection a certain extent, but its effect is not so good, and the null is not in the arrivaldirection of interference. A pattern reshaping method is proposed in this paper, whichis based on the combination of diagonal loading and linear constraints. Diagonalloading method is used to correct the beam direction, and the linear constraints is usedto make sure the beam pattern nulling in the interference direction, so the expectedadaptive beamforming is obtained. |
