| With the rapid development of high-speed railway in China, the demand for transmission of wireless control of train and wireless broadband access has increased. Orthogonal frequency division multiplexing (OFDM) technology has high spectral efficiency, modulation flexible, easy to implement, anti-multipath interference, and other characteristics, has been widely used. OFDM technology has been selected as one of the key technologies for the next generation mobile communications and will be used in high speed environment. Thus, the research on the reliable transmission based on the OFDM technology in the high-speed railway environment has theory and practical value. There are many challenges for OFDM technology that is sensitive to frequency shift to work efficient in the complex railway environment, the channel estimation is one of these factors.The channel estimation method is studied under the high mobile environment in this thesis. Firstly, this paper outlines the wireless fading channel characteristics, mainly on the multi-path fading and Doppler effects. Based on the above, a channel model has been established that is suitable for the high mobile environment. Secondly, the basic principles and several methods of channel estimation are presented. Thirdly, this thesis has established an OFDM baseband simulation model, based on this model, through the simulation using the tool of Matlab to compare the channel estimation performance of different channel estimation algorithm, different pilot insertion method, different pilot intervals, different channel conditions in the fast-moving situation. In the last, a interpolation algorithm based on gray prediction model has been applied that can be used to estimate the channel state information (CSI), simulation shows that in the high-speed mobile environment, the new applied channel estimation interpolation method can obtain a similar estimation performance compared with the second order interpolation. |
