近年來無線區域網路廣泛的發展，在公開的無線區域網路可提供筆記型電腦或是個人數位助理等移動元件連線使用，對於公共無線區域網路而言，有效而且可靠的認證是重要的議題，然而進行交握程序時，這些繁瑣的認證會造成潛在的延遲，甚至於影響到即時性多媒體傳輸的品質。 在本文中將使用預先認證的機制進行快速的交握程序，依據移動元件的移動特性來決定預先認證運作的方法，過程中擷取點會收集移動元件的移動資訊，利用這些資訊來決定預先認證時間以及保留認證資料時間，當預先認證的時間點到達，此擷取點將通知其他鄰近的擷取點進行認證以及保留認證資料的時間，本文中將比較不同的預先認證時間以及保留認證時間所產生的影響。在模擬結果中顯示，利用“預先認證有效率”以及“保留認證所浪費的資源”兩項參數，可以用以決定如何選擇才是最有效且最節省資源的方式，由於在本文所提出之預先認證機制中考慮了移動元件的行為模式，因此有較佳的實驗結果。 Recently, wireless LAN systems have been widely deployed for public mobile Internet services. Portable devices, such as laptop computers, Personal Digital Assistants (PDA), can access Internet services through wireless technology in wireless LAN. In the public wireless LAN systems, reliable authentication and mobility support are the most essential issues from the service point of view. However, re-authentication during handoff always causes long handoff latency and this affects the quality of service in real-time multimedia applications. In this paper, we propose a fast handoff scheme for authentication based on the predictive of mobile behavior. The prediction is made by using the behavior of the mobile devices. Thus, Access Point (AP) collects movement information of mobile devices to decide the time for pre-authentication and the time to reservation. During pre-authentication, AP will notify its neighbor APs for authentication and the time of reservation. The simulation results will illustrate the comparison of the above parameters. In this thesis, both of the authentication effectiveness and the utilization of reserved resources are used to examine the performance of the proposal schemes. As the proposed scheme considers the heuristics of mobile behavior, it demonstrates a quite good performance from our simulation results.
