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標題: IEEE 802.11 無線網路依碰撞率之漫遊決策
IEEE 802.11 Wireless LAN Roaming Based on Congestion Rate
作者: 戴證倫
Tai, Cheng-Lun
關鍵字: Ad-Hoc Wireless LAN
congestion information
出版社: 電機工程學系所
引用: [1] IEEE Computer Society , “Standard for Information Technology - Telecommunications and information exchange between systems - Local and Metropolitan Area networks - Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications,” IEEE 802.11-1999. [2] IEEE Computer Society , ”IEEE Trial-Use Recommended Practice for Multi-Vendor Access Point Interoperability via an Inter-Access Point Protocol Across Distribution Systems Supporting IEEE 802.11 Operation,” IEEE Std 802.11f, 2003. [3] Hongqiang Zhai, Xiang Chen Yuguang Fang, “How Well Can the IEEE 802.11 Wireless LAN Support Quality of Service,” Wireless Communications, IEEE Transactions on Vol. 4, Issue 6, pp. 3084-3094, Nov. 2005. [4] Shwar Ramani, Stefan Savage , “ SyncScan:Practical Fast Handoff for 802.11 Infrastructure Networks,” Proceeding of the IEEE infocom Conference, Miami, FL, March 2005. [5] Fred Halsall , “ Data Communications , Computer Networks and Open Systems 4th Ed,” Addison-Wesley. [6] Mattbew S. Gast , “ 802.11 無線網路技術通論,” O’Reilly , 2003. [7] Manthos Kazantzidis, Mario Gerla ,” End-to-end versus Explicit Feedback Measurement in 802.11 Networks”, In Seventh IEEE. Symposium on Computers and Communications, pp. 429-434, July 2002. [8] IEEE Computer Society, “Standard for Information Technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment : Radio Resource Measurement of Wireless LANs,” IEEE P802.11k,2006. [9] “Tutorial for the Network Simulator ns”, /tutorial/. [10] “AWK Tutorial Guide, version 2.2”, 94/9 4011/,中央研究院計算中心.
摘要: IEEE 802.11無線區域網路中,定義了有基礎架構的無線區域網路 ( Infrastructure Wireless LAN)與無基礎架構的無線區域網路( Ad-Hoc Wireless LAN)這兩種的基本架構,在有基礎架構的無線區域網路中,使用稱為Access Point (AP)的存取點,這個存取點負責將無線網路跟有線網路相互連接,在AP訊號範圍內的行動節點(STA)必須先跟AP註冊才能透過AP存取有線網路的資源。在傳統的802.11協定中,STA只會與訊號強度最強的AP進行註冊,卻忽略考慮AP的通道壅塞情況,本篇論文將提出無線網路依碰撞率之漫遊決策,使STA在訊號強度許可狀況下,得以選擇通道壅塞情況較佳的AP進行註冊。 首先我們使用壅塞情況的預測,讓所有的工作站週期性的偵測目前通道壅塞的狀況,並且將目前偵測到的壅塞情況的資訊附加在封包中傳送出去,在附近的AP收到這些訊息後,利用同步化掃描的方式,將它所收集到的通道的資訊附加在Beacon的封包中,當STA接收到Beacon後,會把通道資訊儲存在比較表內。 本論文中,我們提出一種新的依碰撞率之漫遊決策,利用壅塞資訊,讓STA判斷目前通道壅塞情況來決定是否漫遊,並且計算各個可連結AP的壅塞情況之比值,藉此控制STA漫遊到AP的數量,即可避免大量的工作站同時對相同AP存取,而導致通道負載量過大,藉此讓每個AP的負載取得平衡,並且使工作站在漫遊過後,依然可以提高並且維持良好的通道品質。
The IEEE 802.11 Wireless Local Area Network (WLAN) specification defines two ways to configure a wireless network: infrastructure mode and ad-hoc mode. The infrastructure mode includes an access point (AP) which connects between wireless LAN and wired LAN. Before a station is allowed to send a data message via an AP, it should first become associated with the AP. In conventional IEEE 802.11 protocol, a station associated with the AP that has the strongest SNR. In this thesis, we present a new roaming mechanism based on congestion rate. First of all, a station estimates the congestion condition periodically and piggybacks its congestion information within the transmission packets. After an AP receives the information, it has a complete picture of the channel utilization. Then it uses SyncScan mechanism to send the congestion information to the stations with the Beacon frame. In our proposed roaming mechanism, when a station wants to associate with a new AP, it will use the its congestion information and decides whether to roam or not by calculating the congestion rate of every AP. Wireless station can avoid the station that a large number of stations associate with an AP at the same time. Therefore, we can balance the load of each AP.
其他識別: U0005-0608200715551200
Appears in Collections:電機工程學系所



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