| Summary: | 碩士 === 國立中央大學 === 資訊工程研究所 === 92 === Due to the fact that wireless lan and wireless network are more and more popular, include GPRS、GSM and 3G network. These technology have a rich of mobility, users could get a lot of the newest information through mobile devices, such as PDA, TabletPC, cell phone and notebook. If we integrate positioning technology with mobile devices, users could receive all of the information near neighborhood, for instant, knowing where you are; listing all entertainments, restaurant and scenic spots; and applying location information in some indoor environment, such as museums, super markets, and convenience stores, etc. When users reach a new place, the system gets all kinds of wireless signal to calculate users’ position, and send neighboring information to users automatically. For instant, we calculate the location by GPS and GPRS at outdoors, system could not receive signal of GPS when enter into indoor. System calculates location through getting signal of WLAN and infrared instead of getting signal of GPS. By accuracy of location, WLAN, GPRS and 3G network could not calculate users’ location accurately, we could get more accurate information by other technologies, like GPS or infrared. Therefore, it is very important to develop a positioning mechanism to satisfy every need. We need a Hierarchical Location System to use different technologies in different environments or needs to provide the best location based service.
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