近年來隨著無線網路技術的發達,且因WiMAX(Worldwide Interoperability for Microwave Access,全球互通微波存取)具有傳輸距離長、網路涵蓋範圍廣、高傳輸速率、支援多種工作頻段以及支援語音、影像等數位內容之服務品質需求的特性,所以WiMAX的技術被廣泛應用在數位學習、行動醫療、交通監控、與行動保全等服務應用上。然而若處在一個人口密集度高的城市環境中,當每一個使用者皆使用行動性裝置來收發資訊或是分享影音及數位內容時,將因過多的廣播通訊量而導致通訊不穩定及廣播風暴(Broadcast Storm)的情況發生。因此,在本研究中將依各個行動節點所具有的傳輸特性建立一個包含叢集(Cluster)、Hypercube及Mesh所組成的WiMAX三階層式拓樸架構(Three-Tier based WiMAX,簡稱TTWiMAX),可以有效的減少通訊量使網路的傳輸更有效率。
As a result of the science and technology change with each passing day in Taiwan. Owing to properties of the WiMAX (Worldwide Interoperability for Microwave Access) have long distance of transmission, the wide coverage of network, highly transmission rate, support vary kind of work frequency band, voice & image contents, and the Quality of Service (QoS). Together with today’s multifarious habits and wide application of mobile devices, mobile audio and video, mobile medical service, mobile study and voice keep improving their service qualities. However, in a populated environment, the network becomes unstable and there are broadcast storms because of interferences by excessive communications when many users are using their mobile devices for communications, file or audio/video sharing. Therefore, a three-tier based WiMAX network topology is proposed to reduce the quantity of communication and the network can be made more stable.