Research On Adaptive Beamforming Technology In Downlink Of TD-LTE System

The multi-antenna technologies adopted by the downlink of TD-LTE systeminclude:transmit diversity,spatial multiplexing and beamforming and the three models canswtich adaptivly each other in practical applications,which will be implemented by the systemaccording to different scenarios. Beamforming technology based on the user’s reference signalis able to take full advantage of channel reciprocity between the uplink and downlink in theTime Division Duplex LTE (TD-LTE) system and dynamic adaptive beamform for a singleuser,improving the transmission rate and enhancing cell edge coverage performance.Focusing on the situation of single-user scheduling for TD-LTE system,two dynamicadaptive beamforming transmission schemes:narrow band-EBB and broad band-EBB,basedon the maximum signal-to-noise ratio (MSNR) guidelines in combination with EBBalgorithm,are studied in this paper,three aspects of respectively the uplink channel estimationerror,uplink and downlink channel information delay and terminal mobility rate areimplemented to assess their respective superior performance and the applying scene. theresults show that due to the finer size of weighted particle, narrow-band-of EBB weightedalgorithm has better performance in case of better fit between the uplink and downlinkchannel,while due to the coarse particles,the broadband-EBB weighted algorithm has arelevant stable characteristics of the channel space and so its performance is more robust incase of poorer fitty between the uplink and downlink channel.Changing the means of transmission with a fixed single antenna with the means oftransmission in turn with two antennas in uplink， the singular value decomposition(SVD)of complete channel matrix algorithm based on narrow band-EBB is aslo studied,and afast eigenvalue decomposition of the optimization algorithm based on2order matrix isproposed. Theoretical analysis and simulation results show that compared with the means oftransmission only obtaining a single antenna channel vector, the means of transmission in turn with two antennas can get a more complete channel state information, better matchmaximum ratio combining (MRC) receiver with the two antennas in the downlink, bettertransmission performance and at the same time the optimization algorithm can maintain asimilar block error performance, while it greatly reduces the computational complexity andhas some guiding significance in engineering practice.