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Ku C.-Y.,National Chiao Tung University | Ku C.-Y.,Realtek Joint Research Center | Lin Y.-D.,National Chiao Tung University | Tsao S.-L.,National Chiao Tung University | Lai Y.-C.,National Taiwan University of Science and Technology
IEEE Transactions on Vehicular Technology | Year: 2011

Wireless mesh networking (WMN) is regarded as a low-cost technology for rapid wireless network deployment. However, in a single-channel WMN, the overlapped transmission ranges between relaying mesh points could introduce serious interference. Using multiple radios over multiple channels can decrease the interference and improve the capacity of a WMN, but it increases the cost of a mesh point. One possible solution to balance between interference, hence performance, and cost is utilizing fewer radios that switch among multiple channels instead of using per-channel radios. In this paper, we propose a channel-switching method, called the traffic-aware switching scheme (TRASS), for a mesh point with a limited number of radios. TRASS utilizes the existing IEEE 802.11 mechanisms, i.e., hybrid-coordination-function-controlled channel access and power saving, to avoid packet loss during channel switching. A TRASS mesh point monitors the occupied channel time to schedule radios that switch among channels. The implemented TRASS demonstrates 75% throughput improvement by (2, 1), i.e., two-channel single-radio, over (1, 1). (3, 2) and (3, 1) achieve 69.8% and 39.7%, respectively, of the throughput of (3, 3) in the simulated TRASS. © 2010 IEEE.

Lin Y.-D.,National Chiao Tung University | Lin Y.-D.,Realtek Joint Research Center | Chang S.-L.,National Chiao Tung University | Chang S.-L.,Realtek Joint Research Center | And 2 more authors.
Computer Communications | Year: 2011

Broadcasting by flooding causes the broadcast storm problem in multi-hop wireless networks. This problem becomes more likely in a wireless mesh network (WMN) because WMNs can bridge wired LANs, increasing broadcast traffic and collision probability. Since the network control, routing, and topology maintenance of a WMN highly rely on layer-2 broadcasting, unreliable broadcast algorithms directly destabilize a WMN. Researchers have developed many algorithms for efficient and reliable broadcast in multi-hop wireless networks. However, real-world systems rarely verify or compare these approaches, especially in a WMN. This paper examines six representative broadcast algorithms: simple flooding, dynamic probabilistic, efficient counter-based broadcast, scalable broadcast, domain pruning, and connected-dominating-set based algorithms. This study addresses both common and algorithm-specific implementation in a real-world IEEE 802.11s WMN testbed. Experiments under various topologies and packet lengths reveal the reliability, forwarding ratio, and efficiency of these six algorithms. Quantitative survey results indicate that the scalable broadcast algorithm possesses the best reliability due to its lower collision probability. The domain-pruning algorithm is the most efficient algorithm when considering both reliability and the forwarding ratio. © 2011 Elsevier B.V. All rights reserved.

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