環境中充滿各種無線網路技術，常見的有2G，3G，以及Wi-Fi。目前無線技術的普及，人們可以隨時隨地連上網路進行溝通。但是不同無線網路技術擁有不同的特點，可能適合高速、提供較大頻寬、或更大的涵蓋範圍，相對於不同的系統廠商也會有不同的佈建方式。 針對移動的環境，下一代無線網路技術：IEEE 802.16e (Worldwide Interoperability for Microwave Access，WiMAX)，3GPP release 8 Long Term Evolution (LTE) 等，提供使用者更大的頻寬以及支援更快速的移動。 IEEE 802.21(Media Independent Handover，MIH)，提供了一個共通的界面，使不同網路間可以溝通。使用者便可以平順的切換到各種類型的網路，系統也可以更有效率的分配無線資源。 本篇論文主要是利用IEEE 802.21，結合異質性網路、WiMAX及LTE。並提出演算法來減少使用者需要掃描的基地台數量，以及提出換手的決策機制，來有效提升系統總體效能。模擬結果顯示所提出之演算法可有效達成上述目的。 Various types of wireless access technologies, such as 2G, 3G, and Wi-Fi, have been developed recently. Due to the popularity of these wireless access networks, people can connect to the Internet everywhere at any time. Different kinds of wireless access technologies have different transmission characteristics, some of them may be suitable for high-speed or provide a greater bandwidth, and some may have wider coverage. Carriers deploy those technologies according to different environment and application needs. The next generation wireless network technology, such as IEEE 802.16e (Mobile WiMAX) and 3GPP release 8 Long Term Evolution (LTE), provides users with greater bandwidth and supports mobility capability to accomplish many network services in more convenient and efficient way. IEEE 802.21 (MIH) provides the concept of using common interface for intelligent mobility assistance between different access technologies and to achieve efficient handoff. Users can be able to smoothly switch among various types of network, and the system management system can flexibly allocate valuable radio resources. This thesis focuses on the mobility control on the heterogeneous wireless access network, WiMAX and LTE, by using the MIH heuristic. We adopt the information provided by MIH server to choose proper base stations (BS) list to save users scanning time, and propose an effective algorithm for handoff decision. Our simulation results show that the proposed schemes can effectively meet the above objectives.
