Josh Broch

A performance comparison of multi-hop wireless ad hoc network routing protocols

An ad hoc networkis a collwtion of wirelessmobilenodes dynamically forminga temporarynetworkwithouttheuseof anyexistingnetworkirrfrastructureor centralizedadministration.Dueto the limitedtransmissionrange of ~vlrelessnenvorkinterfaces,multiplenetwork“hops”maybe neededfor onenodeto exchangedata ivithanotheracrox thenetwork.Inrecentyears, a ttiery of nelvroutingprotocols~geted specificallyat this environment havebeen developed.but little pcrfomrartwinformationon mch protocol and no ralistic performancecomparisonbehvwrrthem ISavailable. ~Is paper presentsthe results of a derailedpacket-levelsimulationcomparing fourmulti-hopwirelessad hoc networkroutingprotocolsthatcovera range of designchoices: DSDV,TORA, DSR and AODV. \Vehave extended the /~r-2networksimulatorto accuratelymodelthe MACandphysical-layer behaviorof the IEEE 802.1I wirelessLANstandard,includinga realistic wtrelesstransmissionchannelmodel, and present the resultsof simulations of net(vorksof 50 mobilenodes.

The effects of on-demand behavior in routing protocols for multihop wireless ad hoc networks

A number of different routing protocols proposed for use in multihop wireless ad hoc networks are based in whole or in part on what can be described as on-demand behavior. By on-demand behavior, we mean approaches based only on reaction to the offered traffic being handled by the routing protocol. In this paper, we analyze the use of on-demand behavior in such protocols, focusing on its effect on the routing protocols forwarding latency, overhead cost, and route caching correctness, drawing examples from detailed simulation of the dynamic source routing (DSR) protocol. We study the protocols behavior and the changes introduced by variations on some of the mechanisms that make up the protocol, examining which mechanisms have the greatest impact and exploring the tradeoffs that exist between them.

Supporting hierarchy and heterogeneous interfaces in multi-hop wireless ad hoc networks

Much progress has been made toward solving the problem of routing packets inside an ad hoc network, but there are presently no complete proposals for connecting ad hoc networks together to form larger networks, or for integrating them with wired Internets. We describe a technique that allows a single ad hoc network to span across heterogeneous link layers. Using this technique, we can both integrate ad hoc networks into the hierarchical Internet and support the migration of mobile nodes from the Internet into and out of ad hoc networks via Mobile IP. Taken together, these solutions improve the scalability of flat ad hoc networks by introducing hierarchy, and they enable all nodes participating in the ad hoc network to be reachable from anywhere in the world. We have implemented each of the solutions in a real testbed of 8 nodes using the Dynamic Source Routing (DSR) protocol. Generalizing our solutions, we describe several abstract scenarios and present our ideas for solving them.

Lessons from a full-scale multihop wireless ad hoc network testbed

This article describes our experiences building a multihop wireless ad hoc network of eight nodes driving around a 700 m by 300 m site. Each node runs the dynamic source routing protocol and interfaces seamlessly with existing Internet infrastructure and the Mobile IP protocol. We present quantitative results from data collected during runs of our testbed under a composite workload including voice, bulk data, and real-time data. Based on careful analysis of our data, we highlight radio propagation issues that network protocols will need to address in the future.

Quantitative lessons from a full-scale multi-hop wireless ad hoc network testbed

This paper presents preliminary quantitative results from data collected during runs of our multi-hop wireless ad hoc network testbed. The network successfully carried a composite workload including voice, bulk data, and real-time data. Careful analysis of recorded runs highlights radio propagation issues that network protocols will need to address in the future.

Optimizing wireless network protocols using real-time predictive propagation modeling

A common feature of all wireless mobile data networks is the dynamic nature of the propagation environment. Our work introduces a new level of intelligence into wireless networks by creating a real-time prediction model that runs independently on each mobile node. Such a prediction can assist the routing protocol in making hand-offs or in choosing the best route to a destination, taking into account future RF propagation conditions.