Research On Key Technologies For Spatial Data Wireless Communications Based On Mobile GIS And PDA

Along with the rapid development of embedded technology, the wireless communications and GIS technology, there is a new opportunity for the abroad application of mobile GIS information. Through these methods it can meet the needs of people on spatial information of 4A(anytime, anybody, anywhere, anything). However, poor performance hardware of mobile terminal, narrow bandwidth of wireless networks and slow transmission of spatial data make enormous challenge for the application of mobile GIS information services. This paper intends to put forward some methods on key technologies for spatial data's wireless transmission in mobile GIS and to validate them efficiency and practicability through theory, we develop a Mobile GIS system on PDA, through what people can enjoy the base service of GIS.The composition and characteristics of mobile GIS information services are discussed and related key technologies of mobile GIS information services from technical aspect are analyzed, including the software and hardware elements of mobile terminals, wireless positioning technology of mobile terminals, the module of mobile GIS information services, wireless transmission technology and so on. The above-mentioned is the base research of mobile GIS information services.Spatial data management methods are analyzed and researched in service center and mobile terminal. Through this method it can enhance the efficiency of spatial data wireless transmission.Traditional methods of vector data compression are concluded and analyzed, the deficiencies in traditional methods of vector data compression and the importance of optimal compression on vector data are pointed out. This paper presents the compression optimization algorithms of vector data based on dynamic programming algorithm, a certain extent to solve the low efficiency problems brought by the small storage space of mobile terminal equipments and narrow bandwidth of wireless networks. In order to improve wireless transmission's efficiency, this paper chooses SVG which based on XML as transmission format of spatial data.This paper develops one Mobile GIS application example on PDA. In this system it realizes a series of functions such as the base operation on map, inquiry, GPS localization and GPS navigation, wireless transmission of spatial data, etc.