Collaborative Research: ITR: Fundamental Performance Trade-offs for Ad Hoc Networks

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Abstract:Various types of ad hoc wireless networks have been the subject ofmuch recent interest. For our purposes, these networks can becharacterized as a set of nodes thatcommunicate with each other over wireless channels using little or nofixedinfrastructure. In such a network, to reach itsdestination, a message may need to be forwarded over severalintermediate links. Examples of this type network include mobilead hoc networks (MANET's), sensornetworks, and various hybrid ad hoc/cellular architectures. Suchnetworkshave the advantages of being rapidly deployable and requiring little ornofixed infrastructure. However, efficiently utilizing this type ofnetwork isa challenging task due, in part, to the interference between nodes, thetime-varying nature of the communication channels, the energylimitations of untethered nodes, and thelack of centralized control via, for example, base stations.This project is part of ongoing research with the goal offurthering understanding of basic performance trade-offs for adhoc networks. This work takes a cross layer view andconsiders both physical layer limitations as well as higher layerperformance metrics such as packet throughput. Techniques fromqueueing theory, optimization, and information theory will beutilized in this work. In contrast with our previous work on problems of this type insingle-hop wireless settings, or, that is, models more appropriatefor cases such as cellular networks, where all communication is toor from a single point, in this project, we are focusing on multi-hopad hoc networks, with multiple transmitters and multiplereceivers. In this environment, several new issues complicate theanalysis. These include the routing and forwarding of trafficwithin the network and the scheduling of transmission andreception by each node. Specific problems that are being addressedincludecharacterizing network stability and identifying adaptive resourceallocation policies which maximize packet throughput.