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在本計畫中,我們研究在IEEE 802.16e無線都會廣域網路(Worldwide Interoperability for Microwave Access,WiMAX)中換手連線和新進連線之間頻寬分配問題、ertPS服務之頻寬要求分配和排程技術,以及WiMAX/WiFi整合網路中頻寬分配和計價等問題。本計畫第一年將對新進連線和換手連線頻寬分配問題作深入研究。我們將以理論推導的方式分析無線網路中新進連線與換手連線在不同比例下保留頻寬對於服務品質和系統效能的影響,並且以此理論模型為基礎提出我們的連線允入控制演算法(Connection Admission Control Algorithm)。我們設計的演算法將會考慮目前基地台的網路負擔情況來動態調整允入控制的規則和換手連線之保留頻寬,以提昇換手連線用戶的服務品質,並且同時增加頻寬使用效能。 針對VoWiMAX (Voice over WiMAX)服務,本計畫第二年將針對IEEE 802.16e無線都會廣域網路中延伸即時性輪詢服務(Eextended-real-Time Poling Service;ertPS)設計一動態的頻寬分配和排程機制。ertPS服務類型主要是用來用來提供即時的資料流傳輸,能週期性地傳送可變動大小的封包,其應用服務例如具無聲壓縮的VoIP服務。我們計畫研究及分析VoIP服務在IEEE 802.16e網路中的服務品質,並且同時研究設計ertPS的頻寬要求分配以及排程技術。 前兩年的計畫我們著重在WiMAX網路包括允入控制以及ertPS服務之動態頻寬要求分配方法等技術問題,而在第三年計畫中,我們將對於WiMAX與WiFi的網路整合進行探討。未來當WiMAX都會網路掘起時,未來如何將WiMAX與WiFi的網路做有效之整合將是一個重要的問題。我們計畫以賽局理論中動態賽局(Dynamic game)找出具有優勢equilibrium之研究,對此異質網路之間頻寬資源分配以及計價問題做深入探討,以增進WiMAX/WiFi整合網路之頻寬效能,增加服務提供商營收,同時維持使用者服務品質。
The emerging IEEE 802.16e Worldwide Interoperability for Microwave Access (WiMAX) network is one of the most promising solutions to provide ubiquitous wireless access with high data rates, high mobility, and wide coverage. In the project we study some significant problems in WiMAX mobile networks, including bandwidth reservation for handoffs, bandwidth request/allocation for variable-rate real-time services, and pricing for WiMAX/WiFi integrated networks. In IEEE 802.16e BWA networks, it is important to assure seamless handover for mobile subscriber stations to support quality of services (QoS). For the purpose, the base station needs to reserve a certain amount of bandwidth for handover connections in order to decrease handoff latency and dropping probability. In the first year of this project, we will deeply investigate the bandwidth reservation problem by theoretical and numerical analyses, and we will propose our bandwidth reservation scheme based on the analyses. Our scheme will further consider the network loads to dynamically adjust the call-admission-control (CAC) criteria and the reserved bandwidth for handover connections to both guarantee QoS for handoffs and increase the system utility. In recent years, as the technologies of broadband wireless access (BWA) advance, the needs of wireless multimedia services, such as audio and video streaming applications, IPTV, and video conferencing are increased dramatically. In particular, providing voice services in WiMAX networks is expected to be an important application contending with the traditional telecommunication services in the future. For VoWiMAX services, our project in the second year will focus on the design of a dynamic bandwidth request-allocation and scheduling mechanism for the Extended-real-Time Poling Service (ertPS). The type of ertPS service is primarily used for variable-rate real-time applications, such as VoIP services with silence compression. We will investigate the QoS of VoIP applications based on the ertPS service in IEEE 802.16 network and design a novel bandwidth request-allocation scheme for the ertPS service. In the first two years, we focus on the study of technical problems of WiMAX including the CAC problem and a dynamic bandwidth request-allocation problem; in the third year of our project, we set our sight on a commercial problem, pricing, in an integrated WiMAX/WiFi Network. The 802.11 wireless local area network (WLAN) has already become a mature and popular WLAN technology today. With the rapidly develop of WiMAX technologies, the integration of WiFi and WiMAX networks will be an increasingly important issue in the near future. We plan to apply the dominant strategy equilibrium of a dynamic game, which is based on the game theory, to find the optimal bandwidth-allocation schemes and pricing policy in such the heterogeneous network. With our investigations on the problems of bandwidth reservation for handoffs, bandwidth request/allocation for variable-rate real-time services, and pricing for WiMAX/WiFi integrated networks, we hope to thoroughly provide an in depth view about the system design of IEEE 802.16 WiMAX in the future.