Research On Synchronization Technology Under LTE High-speed Environment

In recent years,with the rapid development of wireless technology,LTE system has been very mature and commercially.At the same time,the development of high speed rail in China is in full swing,the high speed rail network can almost cover all cities,and more and more mobile users on the high speed rail.Currently the railway adopts Railway Global System for Mobile Communications(GSM-R)network,and the network cannot meet the growing demand of high-speed rail communication.Therefore,the implementation of the next generation of railway communication system LTE-R(LTE for Railway)is imminent.During high-speed rail operation,the maximum speed may be greater than 300km/h,which results in a larger Doppler shift.While the OFDM system is a multi carrier system,frequency error would destroy the orthogonality between subcarriers,and lead to ISI and ICI,so how to estimate the frequency offset and compensate frequency error quickly has been an important problem of high iron environment.This paper gives a detailed analysis and simulation of how the timing error and frequency error affect the LTE synchronization process in the LTE-R system,and points out the key factors that affect the synchronization process.Because of the variability of high-speed railway environment,the selection of channel is very important in simulation.The main work of this paper is as follows:1.The principle of OFDM system and the influence of OFDM synchronization are introduced.The frame structure and synchronization sequence used in LTE are introduced.2.Simulate LTE timing and frequency synchronization in the traditional non high-speed railway environment with MATLAB tools.Studied a variety of typical timing synchronization algorithm and frequency offset algorithm and compared its design ideas and performance differences.3.As high speed railway produced high Doppler shift,this paper compared performance based on different factor K and synchronization algorithm with Rician channels.And this paper proposes an improved frequency synchronization algorithm,its design is as below: UE record the frequency error during a period,then calculate the average frequency error,just compensate the XO,and give the improved performance comparison.