Research On The Method Of Downlink Beamforming In TD-LTE System

The LTE system has an outstanding performance in improving the spectrum efficiency, cell edge user's rate and system capacity. It has get lots of attention from operators. As TD-LTE system is based on time division duplex, the uplink and downlink channel reciprocity can be employed for smart antennas. Because the LTE physical layer uses the OFDM technology which is different from the CDMA technology of3G systems, so the integration research of the smart antenna and OFDM technology is very necessary. Beamforming technology is the core of the smart antenna. Although beamforming algorithms have been carried out at home and abroad more in-depth study, but the practical application of research of smart antenna system in LTE is not very mature. so this paper focuses on beamforming in the application of research of TD-LTE. The paper's research is reflected in:(1)Multipath fading channel parameters and characteristics which affect the performance of wireless communication systems are analyzed.And two commonly used models for uniform circular and line array are modeled, and different number of array elements are simulated by using the MATLAB.(2) A detailed study and is carried out for TD-LTE physical layer protocol, which include the frame structure, channel encoding, modulation and signal mapping methods in the resource elements. The traditional algorithms are arraged and improved. A complete beamforming verification platform that is based on the understanding of the physical layer protocol is constructed by using MATLAB.(3) Using the simulation platform to verify the performance of different algorithms in different modulation methods. Terminal demodulation signal to noise ratio and bit error rate curve in different modulation are obtained. The simulation results indicate that the improved algorithm can significantly improve system performance, but the improving level on system gradually decreased with the modulation order increasing.