Synchronization Algorithm And Its Vlsi Implementation Of Dvb-h System

DVB-H is an extension to the mobile termination of DVB-T.As a new generation of Digital Terrestrial Television Broadcast(DTTB) standards,DVB-H was founded according to the service of data of mobile termination and mobile multimedia.To be similar to DVB-T,DVB-H is also based on OFDM technology.OFDM system which is a high-speed transmission technology can effectively resist multi-path delay and improve frequency spectrum utilization.It is also very easy to process the signal by FFT.But in another aspect,the requirement of synchronization for OFDM system is very strict.There must be a stable synchronization loop in the demodulation system.This thesis takes the DVB-H which is based on OFDM as research object.Firstly, it analyses the synchronization technology of OFDM multi-carrier wireless communication.Then,it proposes the implementation scheme of synchronization algorithm and circuit structure.What is more,this design adopts the pilots to realize synchronization in frequency domain,so the synchronization method is not only adapts to DVB-T/H receivers,but also suitable to extend to other communication systems with pilots structure,especially CMMB system.This method makes the multi-standards integration program possible.The main contribution of this dissertation can be concluded as following:(1) Based on the OFDM system model,the synchronization issues of OFDM system are analyzed thoroughly including key technologies of carrier synchronization, sampling synchronization and symbol synchronization.The influence of non-ideal synchronization to the whole system is also quantitatively analyzed.In allusion to DVB-H system,with deep study of the existent synchronization algorithm and the digital communication technology,it proposes the synchronization system algorithm and circuit structure based on DVB-H system.(2) To aim at the multi-transfer mode feature of DVB-H,adopting cycle prefix of OFDM symbol,this work proposes a new method of time synchronization algorithm which can simultaneously accomplish mode detection and jointed estimation of coarse symbol synchronization and fraction carrier frequency offset synchronization.Compared with the lasted algorithm,this method can achieve higher accuracy with the similar hardware complexity.At the same time the residual carrier frequency offset is smaller than two percent sub-carrier interval, so it can meet the design target of the coarse estimation in DVB-H SPEC. (3) Based on the structure of OFDM symbol and information of pilots,this thesis improved the integer carrier frequency estimation which is based on continual pilots.It adopts zero-carrier to execute the integer carrier frequency offset and replace complex multiplication with sliding integration.In this way,the hardware consumption and convergence time are shortened dramatically.With the study of existent research this thesis improves the select ofpararneter of bop filter,which achieve a balance between convergence time and estimation precision.At the same time,it researches the limitation of frequency tracking estimation which meets the demands of tracking range and estimation precision.On the fine symbol synchronization stage,it also uses continual pilots to complete fine symbol estimation.Then,the system performance can be improved through the result of coarse and fine symbol estimation.(4) Based on the research of algorithm in this thesis,the corresponding hardware structure is presented.Firstly the whole architecture of the synchronization loop is depicted,and then the key modules are described respectively,which includes each synchronization modules,the CORDIC circuit,interpolator,etc.With the optimizing algorithms on VLSI architecture,these improvements insure the performance of synchronization loops and diminish the power,area and cost of this circuit.