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The authors survey networking solutions that have been proposed for high-speed packet-switched applications. Using these solutions as examples, they identify the specific problems resulting from very high transmission rates and explain how these problems influence the design of high-speed networks and protocols. They conclude that the solutions based on deflection routing are the most promising ones and suggest a number of directions for their evolution.

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Abstruct -We show how flooding can be adopted as a reliable and efficient routing scheme in ad-hoc wireless moblle networks. It turns out that, with the assistance of some tunable heuristics, flooding is not necessarily inferior to sophisticated point-to-point forwarding schemes, at least for some classes of wireless applcs tions. We discuss a reactive broadcast-based ad-hoc routing prcr tocol in which flooding exhibits a tendency to converge to a narrow strip of nodes along the shortest path between source and destination. The width of this strip can be adjusted automatically or by the user, e.g., in response to varying node density and m e bility patterns, Finally, we point out a certain deficiency inherent in the IEEE 802.11 family of collision avoidance schemes and show how to fii it to provide better service to broadcast-based routing schemes represented by our variant of controlled floo& ing.

SUMMARYWe consider ad hoc wireless networks and the topology control problem defined as minimizing the amount of power needed to maintain connectivity. The issue boils down to selecting the optimum transmission power level at each node based on the position information of reachable nodes. Local decisions regarding the transmission power level induce a subgraph of the maximum powered graph G max in which edges represent direct reachability at maximum power. We propose a new algorithm for constructing minimumenergy path-preserving subgraphs of G max ; i.e. ones minimizing the energy consumption between node pairs. Our algorithm involves a modification to the medium access control (MAC) layer. Its superiority over previous solutions, up to 60% improvement in sparse networks, demonstrates once again that strict protocol layering in wireless networks tends to be detrimental to performance.

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Providing affordable, high-quality healthcare to the elderly while enabling them to live independently longer is of critical importance. In our Smart Condo project, we have deployed a wireless sensor network in an 850-square-foot condominium for assisted living. The sensor network records a variety of events and environmental parameters and feeds the related data into our web-based system. This system is responsible for inferring higher-order information about the activities of the condo's occupant and visualizing the collected information in both a 2D Geographic Information System (GIS) and a 3D virtual world. The architecture is flexible in terms of supported sensor types, analyses, and visualizations through which it communicates this information to its users, including the condo's occupant, their family, and their healthcare providers.

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