Research On The Application Of MIMO-OFDM Technology In The Railway Mobile Digital Television System

With the rapid development of science and technology, the current situation of the radioand television has profoundly changed. Digital TV brings people the richer multimediaaudio-visual enjoyment. Mobile digital TV has been used in different areas, but the existingterrestrial digital TV covering methods do not take the inherent characteristics of the railwaytransport into account, and it is still unable to provide the wealthy real-time TV programs forrailway travelers. Therefore, it becomes increasingly important to research and design a newsystem of mobile digital TV for the high-speed railway.This thesis systematically studies the theoretical characteristics and the existingtechnology of wireless communications in the railway environment, and a solution suitablefor the railway mobile networks transmission is presented. MIMO-OFDM technology is usedto improve the transmission performance of the wireless link.The organization is as follows:Firstly, the mobile digital television theory is introduced. Besides, the three internationalterrestrial Digital TV broadcast standards and two kinds of China’s digital TV standards,DMB-T and ADTB-T, are studied in details. By studying wireless network coverage mode ofthe Digital TV, a high-speed mobile Digital TV system is been planned and designed torealize high-speed railway track with high reliability and uniform coverage.Secondly, the key technology of MIMO-OFDM is studied in depth. Besides, the basicprinciples and the related technology of MIMO and OFDM are introduced briefly. It isshowed through the theoretical analysis and simulation experiments that the MIMO-OFDMtechnology can significantly increase channel capacity, reduce the error rate, and improve thereliability of the system in the mobile digital TV system.Thirdly, the effect to the wireless communication cause by the high-speed moving andthe key technologies are analyzed and explained; according to radio wave transmissioncharacteristics of the wireless transmission channel, the Winner II model is selected as thehigh-speed railway environment communication model. The MIMO channel capacity basedon the Winner II model is studied and simulation analyzed including different antennasintervals, antenna polarization characteristics and antenna toward.Then the solutions of themobile TV transmission system for the high-speed railway is designed and the keytechnologies are studied in depth.Based on all the above work, the MIMO-OFDM technology is applied into the mobileTV wireless transmission system in the high-speed railway, which focuses on theSFBC-OFDM technology; the design of space-frequency coding programs in theSFBC-OFDM system is described in detail. Besides a multi-antenna system (4×4antennasystems) based on MIMO-OFDM technology is designed and made simulation by Matlab Simulink software; Based on the study of the two existing coding scheme, a new codingscheme (orthogonal SFBC-OFDM coding scheme) is proposed; The process of the downlinktransmission of the MIMO-OFDM system is analysised deeply; The performance of SFBCencoding and STBC encoding for the different running speed are compared through thesimulation. And the transmission mode between base station and the receiving end isintroduced, which can improve the transmission performance of the wireless link in thewireless transmission for high-speed rail.