Karim-Algorithms-Chapter - Geographic Services for Wireless...

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1 Geographic Services for Wireless Networks Karim Seada, Ahmed Helmy Electrical Engineering Department, University of Southern California {seada, [email protected] 1. Introduction In wireless ad hoc and sensor networks, building efficient and scalable protocols is a very challenging task due to the lack of infrastructure and the high dynamics. Geographic protocols, that take advantage of the location information of nodes, are very valuable in these environments. The state required to be maintained is minimum and their overhead is low, in addition to their fast response to dynamics. In this chapter, we present a state-of-the-art overview of geographic protocols providing basic functions such as geographic routing, geocasting, service location, and resource discovery. We introduce also some of our work on assessing and improving the robustness of geographic protocols to non-ideal realistic conditions corresponding to the real-world environments. Geographic protocols are very promising for multihop wireless networks. These protocols take advantage of the location information of nodes to provide higher efficiency and scalability. In wireless environments, the locations of nodes correspond to their network connectivity, which makes geographic protocols natural components in these environments and it is expected that they will become major elements for the development of these networks. For obtaining the location information, different kinds of localization systems exist such as GPS, infrastructure- based localization systems, and ad-hoc localization systems. Examples of multihop wireless networks are ad hoc networks and sensor networks. Ad hoc networks are infrastructure-less dynamic networks that could be an extension or alternative to infrastructure wireless networks, especially in situations where it is difficult or time-critical to deploy an infrastructure such as in disaster recovery or military applications. Commercially it could also be used to build small fast networks for conferences and meetings, vehicle networks, rooftop networks, or to extend the services provided by the cellular infrastructure. Sensor
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2 networks are networks of small embedded low-power devices that can operate unattended to monitor and measure different phenomena in the environment. Sensor networks are suited for applications such as habitat monitoring, infrastructure protection, security, and tracking. We consider basic geographic protocols at the network layer: geographic routing, geocasting and geographic rendezvous mechanisms. Geographic routing provides a way to deliver a packet to a destination location, based only on local information and without the need for any extra infrastructure, which makes geographic routing the main basic component for geographic protocols. With the existence of location information, geographic routing provides the most efficient and natural way to route packets comparable to other routing protocols. Geocasting is the delivery of packets to nodes within a certain geographic area. It is an extension to geographic
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This note was uploaded on 05/27/2011 for the course CIS 4930 taught by Professor Staff during the Spring '08 term at University of Florida.

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Karim-Algorithms-Chapter - Geographic Services for Wireless...

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