Analysis of Delay, Capacity, and Capacity Deficit in Multihop

Dr.Nabhendra Bisnik - Rensselaer Polytechnic InstituteMultihop wireless networks, such as wireless ad hoc, sensor, and mesh networks, have applications in a variety of fields like providing connectivity to communities, surveillance, monitoring, defense, etc. However scalability of such networks is marred by scarce bandwidth, broadcast nature of the wireless medium, and dynamic nature of network topology due to node mobility. In this talk we present analytical techniques for characterizing delay, capacity, and the capacity deficit caused by routing protocol overheads. We present a queuing theory approach to evaluate average end-to-end delay and maximum achievable per-node throughput in random access MAC based wireless ad hoc and mesh networks. The model takes into account the number of nodes, the random packet arrival process, the extent of locality of traffic, and the backoff and collision avoidance mechanisms of random access MAC. We model the random access multihop wireless networks as open G/G/1 queuing networks and use the diffusion approximation method for evaluating closed form expressions for average end to end delay. In order to characterize the impact of routing overheads on the actual capacity available to network users for transmitting data we present an information theoretic framework for analyzing the minimum routing overheadincurred by geographic routing in mobile ad hoc networks. We formulate the minimum routing overhead problem as a rate distortion problem and evaluate a lower bound on the minimum routing overhead incurred for routing packets with desired level of reliability. We characterize the effective transport capacity of ad hoc networks available to the users for transmitting data, after taking into account the minimum overheads that must be incurred for reliable routing. We also present results on the critical network size, above which the entire transport capacity of the network may be consumed by the routing overheads

Location: Frank R. Seaver Science Center (SSC) - 319

Audiences: Everyone Is Invited

Contact: Shane Goodoff