臺灣博碩士論文加值系統

無線頻寬是昂貴且有限的，如何有效率的使用頻寬，並同時提供各種類型連線所需的服務品質(Quality of service)在無線網路的應用上是一項很重要的課題。因此，在本篇論文中我們提出了一個以模糊理論(fuzzy theory)為基礎的頻寬保留機制。此機制會在節點有連線需求時為連線保留所需的頻寬，並且在節點頻寬不足時動態的根據頻寬使用的情形調整節點中的頻寬分配。當節點的頻寬不足以提供目前的連線所需的頻寬時，系統會啟動一個頻寬調整機制調整目前節點中的頻寬分配，以防止目前的連線因頻寬不足而無法建立連線。節點的頻寬是否作調整，以及頻寬調整比例的多寡將根據頻寬使用率，和頻寬使用率變化量經模糊化的結果由模糊規則(fuzzy rules)和頻寬使用率的歸屬函數(membership functions)推論決定。使用本文所提出的頻寬保留機制將可有效的利用無線頻寬，並提供各類型連線所需的服務品質。

Wireless bandwidth is expensive and limited. How to use it efficiently and in the meanwhile provide different kinds of traffic QoSs they needed is an important challenge. In order to use precious bandwidth efficiently and to satisfy different kind of QoSs, in this thesis, we propose a fuzzy-based bandwidth reservation mechanism to allocate bandwidth for connections, and dynamically adjust the bandwidth of node. The methodology of the proposed bandwidth reservation mechanism is fuzzy theory. When the available idle bandwidth can’t satisfy the bandwidth requirement of new arriving connections, the system will start a bandwidth adjusting process to adjust the amount of bandwidth to prevent incoming connections block resulted from insufficient bandwidth. The decision of bandwidth adjustment and the amount of bandwidth to be adjusted are made by the intersection of the utilization state of bandwidth and the state of the variation of bandwidth utilization ratio. Making use of the bandwidth reservation mechanism proposed here can prevent bandwidth of nodes from being occupied by some particular traffic and provide QoS to each kind of traffic.

1. Introduction............................................. 1
2. Related Researches....................................... 3
2.1 Ad hoc wireless networks............................. 3
2.1.1. Introduction of ad hoc wireless networks...... 3
2.1.2. Problems of ad hoc networking................. 3
2.2 Approaches to support QoS............................ 4
2.3 Bandwidth reservation mechanisms..................... 6
3. The Proposed Approach.................................... 10
3.1 Essentials of the proposed approach.................. 10
3.2 Bandwidth reservation mechanism...................... 12
3.2.1. Variation of utilization ratio of the bandwidth ................................................... 13
3.2.2. Utilization state of the bandwidth............ 15
3.2.3. Adjustment of the bandwidth................... 16
4. Simulation............................................... 19
4.1 Environment.......................................... 19
4.2 Simulation steps and results......................... 20
5. Conclusions.............................................. 23
References.................................................. 24

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