近年來,網際網路 (Internet) 的發展迅速，再加上網際網路上的各種科技和各種應用程式的蓬勃發展提供了許多便利的服務使得人們上網的時間越來越長。全球資訊網 (World Wide Web) 的熱潮就是一個很好的例子。另一方面，隨著各種行動計算裝置的功能增強以及各種無線網路技術的發展更提供了網際網路使用者的行動的便利性。現在，人們能夠使用他們的筆記型電腦或者是PDA，經過IEEE 802.11無線區域網路或者藍牙等無線網路技術的連結，就可以在任何地點無時無刻地享用網際網路上的各種服務。這樣型態的環境促進了使用者位置資訊的需求，因為當人們有了行動上網的能力之後，他們會要求網路上的應用程式或者服務提供者能夠因應使用者目前的位置而提供最適切的服務給使用者。例如，使用者可以要求服務提供者為他們搜尋最靠近她們目前位置的餐廳。這種型態的服務稱之為位置相關服務 (location-dependent service)。位置相關服務必須取得使用者的位置資訊才能動作，而提供使用者位置資的服務稱為位置服務(location service)。
在本篇論文中，我們著重在以IEEE 802.11無線區域網路的技術為基礎來設計並且開發一套能提供位置資訊的位置資訊平台 (location service platform)。在我們所開發的系統中，我們能從我們所鋪設的802.11無線網路的基礎架構中取得使用者的位置資訊，並且在系統所設置的分散伺服器中管理這些使用者位置資訊。我們的系統在實作上提供基本的查詢功能，讓想要得知位置資訊的人能從系統中查詢到目前正在系統的服務範圍中移動的使用者的位置資訊。更進一步，我們的系統可以和網際網路上的各種應用程式或服務整合以提供位置相關的服務。

The Internet is growing more and more popular in recent years. With the development of the applications and technologies on the Internet such as World Wide Web, people spend much more time on Internet than before, and thus the Internet becomes one part of the human life. At the same time, the proliferation of mobile computing devices and wireless network technologies brings the mobility for Internet Users. Mobile users can use their mobile devices such as PDA and laptops to enjoy the services on the Internet anytime and anywhere with the help of the wireless network technologies such as IEEE 802.11 wireless LAN and Bluetooth. This environment fosters the demand for location information, because mobile users require the applications and services that adapt and respond to the presence of people in their environment. For example, a mobile user can ask a service to search for restaurants, which are close to his location. These services are called location-dependent services. The location-dependent services rely on the location service to provide the location information.
In this thesis, we focus on designing and implementing a location service platform in the large-scale IEEE 802.11 Wireless LAN environment. In the system, we can get the location information of the mobile users from the 802.11 infrastructure network, and manage the location information in distributed servers of the system. Our system provides basic functionality for users to query location information of mobile users roaming in the service area of our system. Furthermore, our system can be integrated with applications on Internet to provide the location-dependent services.

Reference
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﹝2﹞ J. Hightower, and G. Borriello, “Location Systems for Ubiquitous Computing” Computer, Volume: 34 Issue: 8, Aug. 2001, Page(s): 57 -66
﹝3﹞ A. Hills, “Large-Scale Wireless LAN Design” IEEE Communications Magazine, Volume: 39 Issue: 11, Nov. 2001, Page(s): 98 –107
﹝4﹞ IEEE standard for Wireless LAN-Medium Access Control and Physical Layer Specification, P802.11, Nov, 1997
﹝5﹞ C. E. Perkins, “IP mobility support,” IETF RFC 2002, Oct. 1996.
﹝6﹞ Host AP driver Web Site, http://hostap.epitest.fi/.
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