Technical Report MSC-2005-01

Title: Location Awareness in Wireless Ad-Hoc Networks (or How to RLISE a TIGR?)
Authors: Guy korland
Supervisors: Roy Friedman
Abstract: This work presents two loosely coupled results related to ad-hoc networks. The first result is a novel method for obtaining local positioning information, whereas the second result utilizes positioning information to devise transmission schedules that eliminate collisions and reduce energy consumption.

More specifically, position information of nodes in ad hoc networks is useful for routing, efficient service and various applications. Global location systems enable mobile nodes to discover their positions in a global coordinate system using stationary emitters. The efficacy of these systems is a function of the density of mobile nodes deployment and of the stationary emitters. In the first part of this dissertation, we explore the idea of using techniques to estimate nodes coordinates in two (or three) dimensional space, and we propose a distributed positioning method (nicknamed RLISE) based on cooperative position sharing between the mobile devices, enabling great reduction in stationary emitters deployment needed by former methods.

Energy efficiency and collisions avoidance are both critical properties to increase the lifetime and effectiveness of wireless networks. The second part of this dissertation proposes a family of protocols (nicknamed TIGR) for reducing both energy consumption and packets collisions in ad-hoc networks. In particular, this family of protocols offers a tradeoff between bandwidth utilization and power consumption. The proposed algorithms are based on geographic knowledge to form a virtual grid and on synchronized clocks in order to achieve a collision free locally computable transmission schedule. As a side effect of the above a new efficient location service that is adjusted to a grid oriented geo-routing is also presented.

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