Research On Broadband Wireless Video Communication Systems Under High Speed Mobile Environments And The Anti-Inference Technologies In These Systems

One of the important aspects of furture development of wirelesscommunication is its application in some professional area and specialenvironment, among which the broadband wireless video communicationsystem is what we should pay attention to.Two key words about the research in the above mentioned area is―highspeed mobile‖and―broadband‖. High speed means strong Doppler effects tosystem, while broadband often comes with severe multipath interference.Traditional broadband wireless communication techniques such as Digital TVTerrestrial Broadcasting have solved the problems of interference. However,under circumstances of "high speed mobile", the characteristics ofinterference have changed a lot. Thus analysis and optimization should beperformed accordingly. In this dissertation, we firstly find out the keytechniques of two special systems including the high speed railway televisionsingle frequency network (SFN) system and broadband wireless videocommunication system for airplane. Then we get some viewpoints about themethodology of design such professional systems.The content of the dissertation mainly focuses on three aspects: thewireless channel measurement and modeling, system rebuild and design, and research of key algorithms.Firstly, about channel measurement and modeling, we give a brief viewof the characteristics and parameters of wireless channel, as well as theexisting channel measurement methods. Practical channel measumentmethods and equipments are presented, and these equipments are used toperform data collection in railway television SFN system and airplane system.Referenced channel models are proposed accordingly.Secondly, in aspect of system rebuild and design, the dissertationpresents a referenced system design to the railway television SFN system,including the pilot and frame structure design. On the other hand, for airplanesystem, we give the main parts of system design such as parameter selectionand data structure.Finally, the key algorithms in this dissertation are mainly about thechannel estimation and equalization techniques which can mitigate the effectof multipath interferences in high speed mobile environments. The firstalgorithm is an equalization method based on iteration and interferencecancellation which could fully utilize the energy of two strong multipaths inrailway television SFN system. Then another equalization method which hascombined frequency domain feedforward filters and time domain feedbackfilters, could be used in high speed movement environments. Moreover, otherrelated techniques are also studied, including a combination based diversityalgorithm in railway television SFN system and an interleaver design methodin fast fading channels.The above three aspects are based on two practical application. The research of this dissertation settles project problems and gives sometheoretical expansion, centering new characteristics brought by "high speedmobile". Additionally, we get the flow of design of professional system whichcan be presented as―Analysis of environment, system design, and research ofkey technologies".