Analysis And Improvement Of Key Technologies In The High Speed Railway Tv Brocasting System ADTB-R SFN

High speed railway system is the one of which the operation velocity isabove200kilometers per hour. Chinese high speed railway is in rapidexpansion. Recently, Chinese government has planned to invest in expresspassenger lines on a large scale. Moreover, according to the latest surveys,the TV service in the train is the application that people expects. As a result,it can be predicted that in several years the digital TV broadcasting system inhigh speed railway will be in major deployment.Single Frequency Network technology can be utilized in high speedrailway TV. Compared with traditional Multiple Frequency Network, SingleFrequency Network can save spectrum resources and has the convenience inthe frequency layout. As a result, there is a development potential andresearch value in high speed railway TV Single Frequency Networktechnology based on the combination of high speed railway digital TVbroadcasting and Single Frequency Network broadcasting.ADTB-R SFN is the high speed railway TV Single Frequency Networktechnology in being, and it is also the system this dissertation focuses on.This dissertation analyzes in deep detail the ADTB-R SFN and draws upplans for improvements.In the first place, this dissertation gives an overview of ADTB-R SFNsystem, introducing the popular international Digital TV single frequencynetworks that include DVB-T SFN, ATSC SFN, and ADTB-T SFN,analyzing the architecture of ADTB-R SFN, comparing ADTB-R SFN withpopular Digital TV SFN systems. The dissertation introduces the principle ofADTB-R SFN, including the principle of single frequency network time,symbol and frequency synchronization, and the air interface technicalprinciple, pointing out that the two key technologies are SFN synchronization and air interface. In addition, this dissertation introduces thedeployment of system.And then, this dissertation analyzes the key technologies in ADTB-RSFN. Firstly, the dissertation drills down to the ADTB-R SFNsynchronization system, to figure out the instability problems and the areaswhere there is enormous room for improvement. Based on detailed study,this dissertation draws up ADTB-R SFN mega frame synchronizationmechanism based on frame phase synchronization to improve the systemrobustness, time synchronization algorithm based on GPS delay holding toraise the precision of time synchronization, and forward error correctionsynchronization method based on bit replacement of encoder state forquicker synchronization. Moreover, this dissertation put forward twoalternatives in synchronization information transmission including adistribution transmission method of length-variable synchronizationinformation packet, and an insertion method of synchronization information.Secondly, this dissertation analyzes the air interface of ADTB-R SFN system,including path condition and modulation, studying Muti-antenna systemwhich is used as the most important method to conquer the harsh wirelessenvironment of high speed railway TV broad-casting, putting forward anantenna isolation plan to raise the forward-backward rejection ratio, andanalyzing the receiver scheme of air interface.The technology introduced by this dissertation achieved good results inrecent railway field trial and maglev field trial.