以IEEE 802.11無線區域網路為基礎的無線熱點越來越普遍，用來提供無線網際網路使用者不同的資料服務。而以發展中的IEEE 802.16 (WiMAX)系列家族為基礎的無線都會網路技術，可望用來作為WLAN熱點的背後支援之解決方法。 WLAN與WMAN之整合網路可取其各別優勢以提供高品質的傳輸服務。不同無線網路系統之間的無縫換手相對就變得有需要，而且要將其QoS機制與換手程序整合也具一定困難度。 IEEE 802.21 MIH為發展中的網路標準，它可以讓包括802與非802系列之異質網路間的換手及互通性可以實行。這個協定定義了提供連結層更有智能的方法，以及給上層其他相關的網路資訊，以使得異質媒介間的換手達最佳化。 本論文提出以IEEE 802.21 MIH為基礎的機制，使用於IEEE 802.11無線區域網路以及IEEE 802.16無線都會網路之間的無縫換手。我們提出的以MIH支援垂直換手方法可針對兩種不同使用情境。經由模擬實驗證明，本方法可以減少因為換手所造成的系統負載以及提供無線網際網路使用者服務不中斷。 Wireless hotspots based on IEEE 802.11 wireless LAN (WLAN) have become very popular for providing different data services to wireless Internet users. The evolving family of IEEE 802.16 -based wireless metropolitan area network (WMAN) technologies is a promising solution to provide backhaul support for WLAN hotspots. The integrated network of WLAN and WMAN can take advantage of them to offer high quality of service (QoS). Seamless handover between different wireless systems is possible while the Internet’s QoS mechanisms are difficult to integrate into the handover procedures. IEEE 802.21 Media Independent Handover (MIH) is developing standards to enable handover and interoperability between heterogeneous network types including both 802 and non 802 networks. This protocol defines method to provide the related network information and link layer intelligence to the upper layers for optimizes handovers between heterogeneous media. In this thesis, we propose a scheme to make seamless handover between IEEE 802.11 WLAN and IEEE 802.16 WMAN based on IEEE.21 MIH. We propose the method to support vertical handover using MIH for two different scenarios. According to the simulation results, this proposal can decrease system overhead caused by handover and provides service continuity for wireless Internet users.
