Fast Time-varying Channel Estimation And Achievement In High-Speed Mobile Environment

The vehicle communication of low latency and high reliability has caused people's attention in recent years,and it quickly becomes the research hotspot of wireless communication.Compared with the channels of traditional wireless communication,channels of vehicle communication environment are completely different.Especially under the high-speed environment,the channels have the characteristics of highly dynamic change and Doppler frequency shift discrete and sparse,which presents a huge challenge for channel estimation design.Under this background,in this paper we further study of the existing problems of the channel estimation under the high-speed mobile environment,propose some channel estimation solutions which are suitable for this scenario in Orthogonal Frequency Division Multiplexing system(OFDM),and apply these solutions into the filter-OFDM system,which is the future candidate technology of 5G.The main work and achievements of the paper are as follows:(1)A channel estimation algorithm based on data dependent superimposed training(DDST)with inter carrier interference(ICI)mitigation is proposed in the paper,which is suitable for OFDM system.The algorithm takes the DDST as pilot symbols to estimate the channels,which increasing the frequency utilization of the system;and it employs the basis expansion model(BEM)to approximately match the channels,which effectively reducing the requirement of pilot frequency numbers for channel estimation performance.Simultaneously considering the specific scenario of high-speed mobile environment,we eliminate the ICI of the subcarriers at the position of pilot symbols.The simulation results show that the proposed approach has better performance than the traditional DDST channel estimation algorithm in high-speed environment,and it is more reliable in f-OFDM systems(2)A high precision algorithm of carrier frequency offset and channel joint estimation based on DDST is proposed in this paper,which is suitable for OFDM system.This algorithm takes the DDST as pilot symbols to estimate both carrier frequency offset and channels.Carrier frequency offset is estimated via the phase difference between two consecutive OFDM symbols,while the channel estimation is obtained by the multiple symbols channel estimation scheme.It can be concluded from the simulation results that the proposed carrier frequency offset and channel joint estimation algorithm has good performance under OFDM system,moreover,it has wider estimation range of carrier frequency offset in f-OFDM system.