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標題: IEEE 802.11 無線網路通道品質預測之漫遊決策
IEEE 802.11 Wireless LAN Roaming Based on Channel Quality Estimation
作者: 賴彥呈
Lai, Yang-Cheng
關鍵字: Wireless
Quality Estimation
出版社: 電機工程學系所
引用: [1] IEEE 802.11 WG, “ Reference number ISO/IEC 802-11:1999(E) IEEE Std 802.11, 1999 edition. International 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,” 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,” IEEE 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,” Addison-Wesley Publishing Company 4th Ed . [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”, 2002. [8] IEEE P802.11k, “Draft Amendment to STANDARD FOR 2 Telecommunications and Information Exchange Between Systems -LAN/MAN Specific Requirements - 3 Part 11: Wireless Medium Access Control (MAC) and physical layer (PHY) specifications: 4 Specification for Radio Resource Measurement”, 2005. [9] “Tutorial for the Network Simulator ns”, [10] “AWK Tutorial Guide, version 2.2”,,中央研究院計算中心.
摘要: IEEE 802.11無線區域網路中定義了兩種不同操作類型的基本架構: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),在有基礎架構的無線區域網路中,使用一種稱為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訊號範圍內的工作站必須先跟AP註冊才能透過AP存取有線網路的資源,而已經註冊的工作站只會在目前連結的AP訊號衰弱到某一個臨界值時,才會開始掃描尋找其它AP的訊號,並且要超過一個標準值後才會確定漫遊的目標。 首先我們利用同步化掃描,讓AP的Beacon封包在同步化的情況下送出,例如,讓第一個頻道的AP在t秒之後傳送Beacon封包,第二個頻道的AP則在t+d秒之後傳送Beacon封包,同理第三個頻道的AP則在t+2d秒後傳送Beacon封包,而工作站則在預先設定的時間跳到各個頻道接收Beacon封包,讓工作站很快完成掃描的動作。 接著我們提出一種新的工作站漫遊機制,在這個機制下,所有的工作站會週期性的偵測目前通道的品質,並且在傳輸的過程中會將目前偵測到的通道的品質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,就可以了解目前通道的使用狀況,再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,當某個工作站進入無線傳輸的範圍內,欲跟附近的AP註冊的時候,就可以利用Beacon封包內的資訊,選擇一個負載程度比較低的AP來漫遊。
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). APs connect between wireless LAN and wire LAN. Before a station is allowed to send a data message via an AP, it shall first become associated with the AP. Based on the measured SNR from the probe response packets received from each AP, the station will then select the best AP for authentication and association. After a station is associated with an AP, it will wait until the signal of the AP drops to a threshold and start to rescan for new AP's. In this thesis, we present a new handoff scheme for 802.11. Station estimates the channel quality periodically and piggybacks its channel information with the transmission packet. After AP receives the information, it has a complete picture of the channel utilization. Then AP uses SyncScan mechanism to send the channel quality information to the sataions with the Beacon frame. When a station wants to associate with a new AP, it will use the information it received and choose the AP with low channel utilization.
其他識別: U0005-2806200611540900
Appears in Collections:電機工程學系所



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