用於無線網狀網路的視訊會議且利用網路編碼及連鎖反應的網路協定

近來，無線網狀網路由於低前期成本、易於佈署與維護以及可提供可靠服務，已備受關注。而IEEE 802.11技術日益精進，可提供越來越高的頻寬，致使在無線網狀網路上使用高網路流量的應用將會越來越熱門，例如即時的視訊會議應用。為了保持視訊會議中語音與影像的品質，在無線網狀網路中提供服務質量(QoS)是必要的。然而IEEE 802.11使用的分散式協調函式(DCF)難以滿足服務質量需求，且視訊會議需要較高的傳輸速率與雙向的流量造成吞吐量易達到瓶頸。為了克服這些問題，我們採用網路編碼機制並提出連鎖反應的網路協定。網路編碼可以讓許多雙向流量利用廣播一次傳送藉以減少傳送次數來增加吞吐量。除此之外，我們的協定將封包傳送順序做排程以增加同時傳送的節點數與編碼機會。為了方便排程，我們也提供機制將路由路徑建成樹狀來避免不必要的碰撞。最後我們模擬了三種無線網狀網路以驗證我們的協定在視訊會議的應用上可以大幅提昇編碼機會與吞吐量。

關鍵字

網路編碼；媒介存取協定；排程；視訊會議；無線網狀網路

並列摘要

Recently wireless mesh networks (WMNs) have received much attention due to low up-front cost, ease of deployment and maintenance, and reliable service coverage. Now, IEEE 802.11 technologies supply more and more bandwidth and these will become popular for high traffic applications on WMNs, for instance, real-time video conference. To maintain the quality of audio and video for video conferencing, it is required to support quality-of-service (QoS) in WMNs. IEEE 802.11 distributed coordination function (DCF) is hard to satisfy the QoS requirements and traffic reaches the bottleneck since video conferencing needs high traffic rate to transmit real-time video and every link has two-way flows. To overcome these problems, we propose the Ripple-based protocol which applies network coding. Network coding mechanism make some two-way flows can transmit at once to breakthrough traffic bottleneck. Furthermore, our protocol schedules the order of packet transmission that can increase the number of simultaneous transmissions and coding opportunities. In order to scheduling successfully, we construct a tree to avoid unnecessary collisions. This tree is also capable of add flows and remove flows use to integrate background flows or another video conferencing. Finally, we simulate three scenarios about WMNs. These simulations verify our protocol that can significant improve number of coding packets and end-to-end throughput in WMNs.

並列關鍵字

Network coding ； MAC protocol ； scheduling ； video conferencing ； wireless mesh network

參考文獻

[32] R.-G. Cheng, C.-Y. Wang, and L.-H. Liao, “Ripple: a distributed medium access protocol for multi-hop wireless mesh networks,” IEEE Vehicular Technology Conference, pp. 289-293, 2006.

[1] I. F. Akyildiz, X. Wang, and W. Wang, “Wireless mesh networks: a survey,” Computer Networks, vol. 47, pp. 445-487, 2005.

[2] R. Bruno, M. Conti, and E. Gregori, “Mesh networks: commodity multihop ad hoc networks,” IEEE Communications Megazine, vol. 43, pp. 123-131, 2005.

[5] R. Koetter, and M. Médard, “An algebraic approach to network coding,” IEEE/ACM Transactions on Networking, vol. 11, no. 5, pp. 782-795, 2003.

[8] D. S. Lun, N. Ratnakar, R. Koetter, M. Médard, E. Ahmed, and H. Lee, “Achieving minimum cost multicast: a decentralized approach based on network coding,” Proceedings of IEEE INFOCOM, vol. 3, pp. 1607-1617, 2005.

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用於無線網狀網路的視訊會議且利用網路編碼及連鎖反應的網路協定

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