無線網路資源有效分配之研究

The Study of Effective Resource Allocation in Wireless Network

潘士瑋(Shih-Wei Pan)

指導教授 ： 吳中實

國立中央大學/資訊電機學院/通訊工程學系/博士(2011年)

摘要

在複雜和多樣化的無線網路環境中，要達到理想的網路管理機制是十分難以達成的目標。為了改善高無線網路的效能，我們首先分析Binary Exponential Back-off (BEB)演算法的效能。分析的重點在於分析AIFS事件對於網路效能的影響。藉由分析的結果指出，BEB演算法可有效減少碰撞和提高系統的資料Throughput。
引用分析結果，指出在網路負荷重時，高優先話務的服務品質易受低優先話務影響。因此，在論文中我們設計可調式BEB演算法，依據網路負荷調整Contention Window的大小，以保證高優先話務的服務品質。
為提供無線網路完整的管理機制，我們利用Simple Network Management Protocol (SNMP)來管理網路元件。並整合DiffServ, 802.11e和802.3x的網路，提供一完整的QoS管理機制。

關鍵字

Markov Chain Analysis ； 802.11e ； EDCF ； QoS

並列摘要

For complex wireless networks with many tunable parameters and network performance objectives, the task of archiving the idea network management is difficult. To improve the performance of the Binary Exponential Back-off (BEB) scheme of networks, we analyze the performance of BEB to estimate the effect of the heavy load in the 802.11e network. The analysis concerns AIFS events among each back-off procedure and evaluates the saturation throughput of the IEEE 802.11e EDCA (Enhanced Distributed Channel Access) under heterogeneous traffic scenarios. The observation of the analysis model presents the BEB is reducing collisions and improving throughput.
Then, we adapt the contention window mechanism to reduce collisions. However, adaptive contention window algorithms cannot guarantee the absolute priority of the high-priority traffic. Especially in the heavy loading, low-priority traffics will introduce collisions and cause unsuccessful transmission. In order to compensate the strictly priority, the proposed scheme provides the absolute differentiated traffic scheme. Relative priorities are provisioned by adjusting the range of the contention window length of low-priority traffic class. Application requirements and network conditions determinates contention window length. Furthermore, the scheme is simple and easy to implement.
In second issue, the proposal provides corporate networks with a scalability management solution. The proposal is based on differentiated services to enable QoS (Quality of Service) and integrates 802.11e, 802.3x and DiffServ (Differentiated Services) over different enterprise sites. The proposed integrates management implements Simple Network Management Protocol (SNMP) to inform the Hotspot controller and to adapt the contention window (CW) of mobile stations to the heavy network load. In this paper, we describe the design, implementation, and performance evaluation of our solution.

並列關鍵字

QoS ； EDCF ； Markov Chain Analysis ； 802.11e

參考文獻

[1] Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, ISO/IEC IEEE 802.11 Standard 1999.

[3] G. Bianchi, “IEEE 802.11-saturation throughput analysis,” IEEE Commun. Lett., vol. 2, pp. 318-320, Dec. 1998.

[4] G. Bianchi, “Performance analysis of IEEE 802.11 distributed coordination function,” IEEE J. Select. Areas. Commun., vol. 18, pp. 535-547, Mar. 2000.

[5] C. H. Foh and M. Zukerman, “Performance analysis of IEEE 802.11 MAC protocol,” in Proc. European Wireless, Florence, Italy, Feb. 2002.

[6] T. S. Ho and K. C. Chen, “Performance analysis of IEEE 802.11 CSMA/CA medium access control protocol,” in Proc IEEE PIMRC 1996.