Research On Channel Estimation Algorithm Based On OFDM System In Tunnel Environment

With more and more subway are used in real-life operations,it brings great convenience to people's lives.However,when wireless communication is performed therein,it is difficult to receive or transmit a correct communication signal,which affects information exchange in a tunnel environment.The rapid development of communication services,from the second generation of mobile communication voice services,to data,video,video and other high-quality multimedia services with a large amount of information,making people have a higher pursuit for the speed and quality of a variety of communications services.Therefore,under the premise of ensuring the quality of wireless communication in the tunnel environment,how to improve the wireless communication rate has become the most concerned issue.OFDM is one of the most widely used transmission techniques in channel estimation.It has the characteristics of resisting multipath interference,facilitating implemention and supporting efficient adaptive scheduling.With its unique technological advantages,OFDM has become one of the choices for researching wireless communications in tunnel environments.Among them,the LMMSE algorithm can improve the channel estimation performance of the OFDM system in the tunnel environment,but this algorithm has a very large computational complexity and computational complexity.Therefore,this thesis proposes a channel estimation algorithm based on OFDM system in tunnel environment,which can effectively reduce the amount of computation and improve system performance.The main research contents are arranged as follows:(1)The research background and significance of this thesis are introduced,and the propagation characteristics of radio waves in free space are analyzed and extended to the propagation characteristics of radio waves in tunnels.Additionally,the traditional deterministic and statistical channel model in the tunnel environment is analyzed.Besides,the two models are compared and analyzed,and the model_improved tunnel channel model to be studied in this paper is determined.(2)The OFDM system is introduced,and the tunnel channel model based on OFDM system is established.According to the different tunnel conditions-straight-through tunnel and curved tunnel,in the MATLAB simulation platform,the traditional channel estimation algorithm are simulated and compared in the two different tunnel environments,using the improved and statistical tunnel channel models established in this paper.(3)The channel estimation algorithm based on LMMSE is studied,and the autocorrelation matrix in this algorithm is improved in time domain.The results show that the improved LMMSE algorithm can effectively reduce the mean square error(MSE)and the biterror rate(BER)performance of the two tunnel models compared with the traditional statistical tunnel model.Moreover,the improved tunnel channel model constructed in this paper is better than the traditional statistical tunnel model.The simulation results show that the improved LMMSE algorithm can effectively improve the operating rate of the system and the system performance of the wireless communication receiver in the subway,and can obtain higher system performance in the improved tunnel channel model of this paper.It has a certain application prospect.Figure [34] table [3] reference [73]...