多重頻道無線網狀網路媒介存取控制協定之改進

無線網狀網路(Wireless Mesh Network，WMN)，如無線隨意網路，每個節點亦必須有路由器功能幫忙轉傳封包。在IEEE 802.11無線區域網路標準中提供多個不互相干擾的頻道。在無線網狀網路中可利用多個不互相干擾的頻道，提升整體網路頻寬以及效能。而在IEEE 802.11標準的媒介存取控制協定(MAC Protocol)僅針對單一頻道及單一介面(Single channel Signle-interface)的環境所設計，並不完全適用在多重頻道多重介面(Multi-channel Multi-interface)的環境中使用。在這篇論文，我們針對無線網狀網路架構下使用多重頻道多重介面的環境提出新的MAC協定。此MAC協定屬於混合式頻道配置，以解決多重頻道的頻道協調問題(Rendezvous)。在先前的論文中，使用靜態配置或以目前節點中封包個數為依據配置個別頻道可停留的時間。在本篇論文，我們提出了依據目前佇列封包的優先權重動態配置頻道可停留的時間。另外，為了減少多重頻道切換後，等待時間的影響，提出以附近傳輸的資料量作為依據，動態配置頻道的等待時間，有效利用所有頻寬，並提升整體效能。在實驗結果中，我們依據不同的環境以及傳輸資料量，顯示出本篇所提出新的MAC協定比先前所提出的混合式頻道配置的MAC協定擁有更好的效能。

關鍵字

無線網狀網路；多重頻道；多重介面；等待時間；混合式頻道配置

並列摘要

Nodes in Wireless Mesh Networks (WMNs), like in ad hoc networks, work not only as a host but also as a router. Packets are forwarded between nodes toward a gateway in a multi-hop way. Multiple non-overlapping channels specified by the IEEE 802.11 Wireless LAN standard can be used simultaneously to increase the aggregate bandwidth. However, multi-channel multi-interface protocols may incur a type of hidden terminal problems. We found that the existing multi-channel multi-interface IEEE 802.11 Medium Access Control (MAC) protocols have room to be improved in the approach to the multi-channel hidden terminal problem, where a static waiting time scheme is used. In this paper, we propose an enhanced MAC protocol with a hybrid channel assignment strategy and a dynamic waiting time scheme for multi-channel multi-interface WMN to avoid the multi-channel hidden terminal problem. The proposed dynamic waiting time scheme assigns waiting time for each channel by using the information of nearby traffic load to utilize the available bandwidth and reduce the end to end delay. From simulation results, we show that the proposed MAC protocol can increase system throughput and decrease packet end to end delay.

並列關鍵字

Wireless Mesh Networks ； Multiple channel ； Multiple interface ； Waiting Time ； Hybrid Channel Assignment

參考文獻

[1] I.F. Akyildiz, X. Wang, W. Wang, Wireless mesh networks: a survey, Computer Network Journal (Elsevier), 47 vol.4:445-487 2005

[4] S. Xu and T. Saadawi, “Does the IEEE 802.11 MAC protocol work well in multi-hop ad hoc networks?”, IEEE Community. Magazine., June 2001

[5] J. Jun and M.L. Sichitiu, The nominal capacity of wireless mesh networks, IEEE Wireless Communications Oct 2003 vol.5, pp. 8–14

[9] C.-Y. Chang, H.-C. Sun and C.-C. Hsieh, ”MCDA: An Efficient Multi-Channel MAC Protocol for 802.11 Wireless LAN with Directional Antenna,” In Proc. of AINA, vol. 2, pp. 64-67, 2005.

[10] A. Raniwala and T. Chiueh, “Architecture and Algorithms for an IEEE 802.11-Based Multi- Channel Wireless Mesh Network,” in IEEE Infocom, 2005.

國際替代計量

多重頻道無線網狀網路媒介存取控制協定之改進

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