無線區域網路之群組同步分散式協調機制在工廠無線感測網路上的效能分析

近年來，IEEE 802.11通訊協定已標準化了無線區域網路，其主要媒體存取控制技術為分散式協調機制 (DCF)。然而，隨著大型感測網路的浮現，：工廠無線感測網路 (IWSN)、物聯網 (Internet of Things)、智慧型電網 (Smart Grid)和智慧交通系統 (ITS)，此類有大量用戶端作為感測節點並同時競爭通道，會造成分散式協調機制效能低下，其原因在於CSMA/CA屬於載波感測機制，IEEE 802.11為了避免碰撞而採用倒退時間 (Backoff)，在大量的用戶端倒退至零時，此時便會增加傳輸碰撞的機率。因此，改善分散式協調機制的效能已成為挑戰性議題。在IEEE 802.11ah標準中提出使用群組化用戶端的方式來減少用戶端彼此之間的競爭，改善通訊效率。然而，如何分配群組個數、群組大小和存取時間仍存在許多議題。在本文，我們以工廠無線感測網路為目標，針對群組同步分散式協調機制提出全面性的效能分析。本論文的背景在工廠環境之下，使用傳統分散式協調機制 (DCF)、群組同步分散式協調機制 (GS-DCF)以及強健傳輸排程演算法 (RCTSBD) 以C語言撰寫模擬程式進行效能分析，其結果顯示群組同步分散式協調機制在吞吐量上有更好的表現，適合在工廠無線感測網路運作。

關鍵字

效能分析；群組同步分散式協調機制；工廠感測無線網路；通道存取控制

並列摘要

In recent years, the IEEE 802.11 protocol has been the standard in wireless local area networks, and its main media access control technique is the distributed coordination function (DCF). However, with the large-scale sensor networks emerging, e.g., the factory wireless sensor networks, Internet of Things, smart grid and intelligent transportation systems, and a large number of sensor nodes competing the channel, DCF will cause poor performance. In the IEEE 802.11ah network, stations can be divided into groups and each group is only allowed to access wireless channel during designated channel access period. However, how to design the number of groups, the group size and channel access period is an open issue. In this thesis, under the industrial factory environment, we study the performance of DCF, RCTSBD and GS-DCF by running simulation programs written in C language. Due to GS-DCF grouping strategy, the result shows that GS-DCF gets higher saturation throughput than the others.

並列關鍵字

GS-DCF ； Industrial Wireless Sensor Network ； Medium Access Control

參考文獻

[1] 鄭暐哲,“應用於無線感測網路之無失真資料壓縮演算法,”碩士論文, 2013.

[2] E. Toscano and L. Lo Bello, “A novel approach for data forwarding in industrial wireless sensor networks,” in IEEE Conference on Emerging Technologies and Factory Automation (ETFA '10), 2010, pp. 1-10

[3] G. Bianchi, “Performance Analysis of the IEEE 802.11 Distribution Coordination Function,” IEEE Journal on Selected Areas Communications, Vol.18, No. 3, March 2000

[6] L. Zheng, M. Ni, L. Cai, J. Pan, C. Ghosh, K. Doppler, “Performance Analysis of Group-Synchronized DCF for Dense IEEE 802.11 Networks,” unpublished.

[7] 張心芳、丁品熏、侯廷昭,“適用於工廠無線感測網路中具延遲界限之傳輸排程協定,”NST 全國電信研討會, 2012.

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無線區域網路之群組同步分散式協調機制在工廠無線感測網路上的效能分析

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