Quality of Service in Ad-Hoc Networks

SPEAKER: Mr. Rajarshi Gupta, UC BerkeleyABSTRACT: QoS mechanisms in the routing layer are insufficient, when distributed scheduling in MAC protocols like 802.11 is unfair. We first propose a novel backoff scheme that attains a higher degree of MAC fairness, by favoring congested nodes during scheduling. We prove the stability and optimality of the new scheme using Markov analysis, and use simulations to study its performance in larger random networks as well.We then address the feasibility of a given set of flows on an arbitrary ad-hoc network, by modeling the interference between links as a conflict graph. To provide sufficient conditions for feasibility, we propose clique-based constraints that are computationally simple, and may be evaluated in a distributed fashion.We use the above framework to design QoS routing algorithms for ad-hoc networks, that take interference into account. We demonstrate the efficacy of a distributed ad-hoc shortest widest path algorithm. We further propose IQ Routing - a source-based heuristic mechanism that is able to select QoS routed paths in a dynamic manner, using only localized state information.Bio: Rajarshi Gupta is a PhD candidate in EECS at UC Berkeley, and will graduate in May 2005. Prior to this, he completed his MS in 1999 at Berkeley, and his BS in 1997 at the U. of Maryland. From 1999 to 2003, Rajarshi worked with Extreme Networks as a Senior Designer, where he has been the author of 8 patents. He is interested in algorithms to ensure quality in networks - both wired and ad-hoc. This includes: analysis of network capacity; switching and scheduling mechanisms for efficient utilization of resources; and, routing algorithms to guarantee quality of service.Host: Dr. Michael Neely, mjneely@usc.edu

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Mayumi Thrasher