The Key Technology For Global Roaming Based On Terrestrial Digital Television Broadcasting Systems

The global roaming technique for the next-generation terrestrial digital television broadcasting(DTTB)system is studied in this thesis.In order to solve the key issues and challenges for the global roaming in DTTB networks,the thesis emphasizes on the worldwide broadcasting roaming framework for mobile terminals,and efficient signal detection and mode recognition scheme for multi-standard DTTB systems.First of all,the background of global roaming based on DTTB system is introduced;its development and further trend of existing terrestrial television standards around the world are summarized.Moreover,the technical problems faced by DTTB global roaming is illustrated,including the mobile terminal roaming,wireless signal mode recognition,and union receiver structure available for multi-standards DTTB system.Furthermore,the system structures and technical characteristics of four existing DTTB standards are analyzed,especially focusing on their signal frame formats.Subsequently,the typical roaming schemes and corresponding key technologies of the existing mobile communication networks are described,such as Global System for Mobile Communication(GSM)and the 3rd Generation Partnership Project(3GPP)mobile communication networks.Then the key differences between DTTB roaming and mobile communication roaming are summarized.Based on the above analysis and discussion,a DTTB global roaming scheme is proposed.The system framework,process steps and key modules of this scheme are given in detail.To solve the difficult problems in the worldwide mobile roaming services for DTTB system,a unified user identity(ID)authentication mechanism among the DTTB operators and user mobile terminal is developed.Several new functionalities including the user ID certification and mobility management are established cooperatively among the home and roaming operators.In addition,an asymmetric encryption based on key exchange is presented to improve the reliability and security in roaming registration.Finally,the basic principle of wireless signal detection and recognition is introduced.Considering the asymptotic-Gaussianity distribution of orthogonal frequency division multiplexing(OFDM)signal,a blind data recognition algorithm based on Wavelet Transform for multi-carrier signals is firstly introduced.Since the performance of blind data detection deteriorates under the fading channel condition,the thesis has explored the structural characteristics of the training sequences inserted in various DTTB signals including cyclic prefix(CP)and pseudo-noise(PN)sequence.By the experience-based research and analysis,a novel multi-carrier signal detection scheme based on CP-OFDM for DVB-T and ISDB-T signals,and four PN detection schemes based on the special frame headers for DTMB and ATSC signals are proposed.The corresponding three key problems in terms of the correlation detection algorithms,hypothesis test model,and statistical threshold optimization are discussed in detail.The overall performances of the proposed schemes are well confirmed through sufficient numerical simulation using Matlab.