在異質無線網路下以快速連結網路的方法改善垂直換手程序

Abstract

隨著網際網路及無線通訊網路發展，人們期望可以透過行動裝置在各種不同的網路間任意地遊走。為了能夠持續網路連線讓服務不中斷，行動裝置必須切換到不同的基地台，這個動作稱為換手。但因為各種無線技術所提供的網路存取媒介並不相同，要如何協調、管理不同媒介的使用，對於進行異質性網路之間的垂直換手將會是一大挑戰。在本論文研究中，我們探討IEEE 802.21的媒介獨立換手機制，透過此機制的支援來改善換手的延遲時間。除此之外，我們定義了周邊網路溝通所需之資訊，使得在異質網路上進行換手時，可以透過訊息的交換，更快速地建立網路的連線，以期達到連續性的服務及無接縫的換手。

With the developments of the Internet and wireless networks, people further expect to roam among heterogeneous networks by mobile devices. When the mobile device changes it connection between different base stations, the seamless handover is required to maintain the services continuously. It is a great challenge to integrate and manage these different media types during the vertical handover between heterogeneous wireless networks. In this thesis, we focus on the Media Independent Handover Functions (MIH Functions) of the IEEE 802.21. By applying MIH functions to WiMAX and Wi-Fi, the handover latency can be reduced significantly. Furthermore, a fast association method is proposed to reduce the scanning latency during the handover. The simulation results show that the proposed method can provide the continuous services and seamless handover for the mobile device roaming among heterogeneous wireless networks.