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研究生:王嘉源
研究生(外文):Jia-Yuan Wang
論文名稱:無線區域網路具服務品質保證之競爭性通道存取的效能研究
論文名稱(外文):On the Performance of Contention-Based Channel Access in IEEE 802.11e
指導教授:竇奇
指導教授(外文):Chie Dou
學位類別:碩士
校院名稱:國立雲林科技大學
系所名稱:電機工程系碩士班
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:59
中文關鍵詞:無線區域網路服務品質保證即時性資料通道存取效能
外文關鍵詞:QoSWLANReal-Time DataChannel Utilization
相關次數:
  • 被引用被引用:3
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  • 下載下載:24
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無線區域網路(Wireless LAN)預期將在家庭內部網路(home-networking environment)及公眾小區域無線網路(hot spot)中,開始提供使用者各種不同的服務,包含語音(Voice)、影像、網頁瀏覽和下載。為了保證即時性資料的服務品質,IEEE 802.11 Task Group E正著手進行對加入服務品質保證的無線區域網路MAC層的草案提議,名為IEEE 802.11e。

IEEE 802.11e在MAC層加強了多種方法來達到服務品質保證目標。這些方法包括:HCCA(HCF Controlled Channel Access)、EDCA(Enhanced Distributed Channel Access)、CAP(Controlled Access Phase)、GA(Group Ack)、DLP(Direct Link Protocol)等。本論文針對即時性資料(Voice、Video)的傳輸要求,找出合適的傳輸時間Polled TXOP(Transmission Opportunities)。模擬結果發現Polled TXP時間長度不但影響即時性資料傳輸的服務品質,還關係到整體通道使用率和best-effort資料傳輸量的表現以及容許輪詢工作站數目的多寡。另外,也發現到EDCA參數AIFS(Arbitration Inter-Frame Space)、CWmin(Contention Window)變化的組合對整體效能的影響,並從中找出提高整個系統工作效能的最佳組合方式。

本論文將對IEEE802.11e中HCCA、EDCA的存取方式,以Matlab程式語言完成系統模擬,並將實驗數據作進一步分析,歸納出結論與建議。
WLANs are expected to become widely deployed in home-networking environment, and the so-called hot spots to use voice, streaming video, and Web-browsing data services. The IEEE 802.11 Task Group E has been working on a proposal for QoS Enhancements to the IEEE 802.11 MAC, namely the IEEE 802.11e proposed standard.
IEEE 802.11e has enhanced many kinds of methods to reach the quality of service (QoS) on MAC layer. These methods include HCCA (HCF Controlled Channel Access), EDCA (Enhanced Distributed Channel Access), CAP (Controlled Access Phase), GA (Group Ack), DLP (Direct Link Protocol), etc. This thesis finds out the suitable CFP (Contention Free Period) Polled TXOP for real-time services. Simulation results show the Polled TXOP length affects the QoS of real-time services, the performance of channel utilization, the throughput of best-effort services, and the number of the admitted stations. In addition, we find the effect of the combination of EDCA parameters by changing the value settings of AIFS and CWmin upon the whole efficiency, then find the optimal solution to improve the efficiency of the whole system.
This thesis focuses on the access methods of HCCA and EDCA of IEEE 802.11e. We use Matlab to complete the system simulation and to analyze the data of experiment, then make a conclusion and suggestions.
中文摘要----------------------------------------------------------------------i
英文摘要---------------------------------------------------------------------ii
誌謝------------------------------------------------------------------------iii
目錄-------------------------------------------------------------------------iv
表目錄-----------------------------------------------------------------------vi
圖目錄----------------------------------------------------------------------vii
第一章 緒論-----------------------------------------------------------------1
1.1 研究動機-------------------------------------------------------------1
1.2 研究目的-------------------------------------------------------------1
1.3 研究方法與內容-------------------------------------------------------3
1.4 各章提要-------------------------------------------------------------3
第二章 具服務品質保證之802.11e的MAC層簡介-----------------------------------4
2.1 IEEE 802.11e的簡介---------------------------------------------------4
2.2 IEEE 802.11e的MAC層--------------------------------------------------8
2.2.1 EDCA相關參數的定義---------------------------------------------------8
2.2.2 EDCA的運作情形------------------------------------------------------10
2.2.3 HCCA相關參數的定義--------------------------------------------------13
2.2.4 HCCA的運作情形------------------------------------------------------17
2.2.4.1 Controlled Access Period (CAP)的定義--------------------------------19
2.2.4.2 CFP、CAP的重送機制--------------------------------------------------20
2.2.4.3 CFP、CAP中Null frame的應用------------------------------------------22
2.2.4.4 CFP、CAP的結束方式--------------------------------------------------22
2.2.4.5 CFP的NAV設定方式----------------------------------------------------23
2.2.4.6 CFP、CAP的TXOP請求方式----------------------------------------------23
第三章 系統模擬------------------------------------------------------------24
3.1 前言----------------------------------------------------------------24
3.2 系統模型------------------------------------------------------------24
3.2.1 真實的即時性資料來源------------------------------------------------25
3.2.2 採用非完美的通道----------------------------------------------------27
3.2.3 準確的訊框傳輸時間--------------------------------------------------27
3.2.4 合適的Polled TXOP長度-----------------------------------------------28
3.2.5 HCCA模擬Case的建立--------------------------------------------------34
3.2.6 EDCA參數模型的建立--------------------------------------------------34
第四章 數據分析------------------------------------------------------------36
4.1 模擬結果(1)---------------------------------------------------------36
4.2 數據分析(1)---------------------------------------------------------40
4.2.1 Polled TXOP長度對容許工作站數目的影響-------------------------------40
4.2.2 Polled TXOP長度對AC_VI or AC_VO資料量的影響-------------------------40
4.2.3 參數AIFS對通道使用率、AC_BK和AC_BE 取得EDCA TXOP時間的影響----------41
4.2.4 參數CWmin對通道使用率、AC_BK和AC_BE取得EDCA TXOP時間的影響----------42
4.2.5 參數AIFS、CWmin對AC_VI、AC_VO丟棄量的影響---------------------------43
4.3 模擬結果(2)---------------------------------------------------------44
4.4 數據分析(2)---------------------------------------------------------48
4.4.1 在固定工作站數目、不同traffic stream分配下,Polled TXOP長度對於AC_VI、
AC_VO資料量的影響---------------------------------------------------48
4.4.2 AC_VI、AC_VO資料量對通道使用率、AC_BK和AC_BE取得EDCA TXOP時間的影響-48
第五章 結論與未來研究方向--------------------------------------------------50
附 錄 --------------------------------------------------------------------52
參考文獻 --------------------------------------------------------------------57
作者簡歷 --------------------------------------------------------------------59
[1] IEEE Std 802.11-1999 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 Std 802.11e/D5.0 July 2003, Draft Supplement to IEEE standard for Telecommunications and Information exchange between systems – LANMAN specific requirements. Part 11: wireless LAN Medium Access Control (MAC)and Physical Layer(PHY).
[3] IBM Zurich Research Laboratory, “Performance Evaluation of the QoS Enhanced IEEE 802.11e MAC Layer,” Research Report, Oct. 2002.
[4] Sunghyun Choi, “Emerging IEEE 802.11e WLAN for Quality-of-Service (QoS) Provisioning,” Telecommunications Review, vol.12, no.6, December 2002.
[5] S. Mangold, S. Choi, P. May and G. Hiertz, “IEEE 802.11e - Fair Resource Sharing between Overlapping Basic Service Sets,” in Proc. PIMRC 2002, pp.166-171, Sept. 2002.
[6] S. Mangold, “IEEE 802.11e Wireless LAN for Quality of Service,” in Proc. European Wireless ’02, Florence, Italy, Feb. 2002.
[7] A. Grilo, M. Macedo and M. Nunes, “A scheduling algorithm for QoS support in IEEE802.11e Networks,” Wireless Communications, vol.10, issue 3, pp.36-43, June 2003.
[8] Magis Networks, Inc. “IEEE 802.11e/a Throughput Analysis,” Magis Document #E10282, 2003.
[9] P. Brady, “A model for generating on-off speech patterns in two-way conversation,” Bell Syst. Tech. Journal, vol.48, no.7, pp.2245-2272, Sept.1969.
[10] Resources for the MATLAB and Simulink user community, “ IEEE 802.11a WLAN model,” <http://www.mathworks.com/matlabcentral>

[11] S. Mangold, S. Choi and N. Esseling, “ An Error Model for Radio Transmissions of Wireless LANs at 5GHz,” Proc. 10th Symp. Signal Theory, Aachen, Germany, Sept. 2001.
[12] IEEE Std 802.11a-1999 Supplement to IEEE standard for information technology - telecommunications and information exchange between systems – local and metropolitan area networks – specific c requirements. Part 11:wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) , 1999. Networks-specific Requirements-part 11: Wireless Lan Medium Access Control (MAC) And Physical Layer (PHY) Specifications, 1999.
[13] Antonio Grilo and Mario Nunes, “Performance Evaluation of IEEE 802.11e,” PIMRC 2002, vol.1, pp. 511-517, Sept. 2002.
[14] Chie Dou, Yang-Jie Chen and Jia-Yuan Wang, “The performance study of contention-based differentiation mechanisms in IEEE 802.11e MAC layer,” in Proc. PIMRC 2003, Vol. 2, Sept. 2003.
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