Research On Key Techniques For New Generation Terrestrial Digital Television Broadcasting Systems

Key technologies applied in the next generation of Digital Terrestrial Television Broadcasting(DTTB)systems are studied in this paper.In order to solve the difficult problem of DTTB,the thesis focus on two key technologies involved in the second generation of Digital Video Broadcast-Terrestrial(DVB-T2): reliable receiver synchronization scheme in dual selective fading channel as well as signal detection and multi-pattern recognition method.Firstly,the paper introduces the development course and evolution direction of several international DTTB standards,discusses the development trend of the new generation DTTB,and analyzes the key problems of the new generation DTTB in combination with DVB-T2.Further,for the receiver synchronization and signal detection problems of DVB-T2 system,feasible solutions are analyzed,the frame structure of DVB-T2 system and characteristics of wireless broadcast channel are dissected,and the advantages and disadvantages of existing methods and performance are summarized.Secondly,according to the characteristics of DVB-T2 system,the influence of timefrequency synchronization deviation on system performance is analyzed.Then,a DVB-T2 receiver time-frequency synchronization scheme is proposed,including frame synchronization acquisition,symbol timing synchronization,carrier frequency synchronization and frequency offset compensation and so on.The key methods used in each link are analyzed,and the rough symbol timing and fine deviation estimation are improved.First of all,the center position of the correlation peak platform is used as the coarse synchronization position to enhance the robustness of the rough symbol timing synchronization in the dual selective channel,and the channel maximum multipath delay information can be obtained.Besides,the scheme uses the evenly distributed scattered pilots for the estimation of the fine frequency offsets and the sampling clock offsets to effectively improve the accuracy of the estimation of the two offsets.Theoretical analysis and simulation results show that compared with the traditional method,the proposed timefrequency synchronization scheme can obviously improve the accuracy of symbol timing and carrier frequency/sampling clock deviation estimation accuracy under a variety of terrible channel conditions.Finally,a new scheme of DVB-T2 signal detection and recognition is proposed,which is based on the problem that the detection probability in the cyclic prefix-based and the pilotbased detection method under the terrible transmission environment is low,and the dependency of the prior information is high.The proposed includes the detection of DVBT2 signal and the recognition of its subcarriers number and the guard interval.In particular,the signal detection in this scheme adopts an improved frequency domain pilot based detection method in the time domain.By improving the decision statistic and decision criterion,the algorithm complexity is improved and the detection performance is improved.At the same time,the subcarrier number identification can be accomplished.The pattern recognition in the proposed scheme uses the optimized cyclic prefix based autocorrelation method,which calculates the correlation peak platform width to obtain the guard interval information.The theoretical analysis and Matlab simulation show that compared with the traditional signal detection and identification method,the proposed scheme can effectively improve the probability of detection and probability of successful recognition under the double selective channel,and can reduce the false alarm probability.On the other hand,the proposed scheme is less dependent on the priori information and more conducive to the actual system applications.