EXPERIMENTAL STUDY OF WIRELESS Ad Hoc NETWORKS
An ad hoc network is a collection of wireless hosts that spontaneously forms a network without the use of any existing network infrastructure or centralized administration. Due to the limited transmission range of wireless network interfaces, multiple network "hops" may be needed for one node to exchange data with another node across the network. Thus, individual nodes must also act as routers. The routing problem gets complex if the nodes are mobile. Dynamic routing in the face of topological changes is an important problem in such mobile ad hoc networks. Such networks find tremendous applications in any type of mobile collaborative applications, where the network must be set up on the fly. Examples include emergency response, law enforcement,explorations, conferencing and military. Not all ad hoc networks are mobile. A network of embedded sensors collaborating to perform a high level sensing task is one such example. Since sensor nodes are powered by battery and sensor networks must be operational in an unattended fashion for a long time,solving problems with low communication overhead is critical. This means communication must be primarily local. The overall goal of this thesis is to perform experimental study on real ad hoc network testbeds. Two types of network testbeds have been used – (i) a mobile ad hoc network using NovaRoam wireless IP routers,and (ii) a sensor network using the Berkeley MICA mote platform. Our focus is experimental protocol design and evaluation on these testbeds. In the NovaRoam-based mobile ad hoc network testbed, we have implemented a version of the well-known AODV (Ad hoc On Demand Distance Vector) routing protocol. It has been implemented as a part of the usual TCP/IP protocol stack. This thesis presents the design decisions for this implementation, as well as performance evaluation of dynamic multihop routing using UDP and TCP on this testbed. As demonstrated in current literature, the performance degrades with larger number of hops in the network and with high offered load. To exercise the sensor network testbed, we have focused on a collaborative monitoring problem. We have developed a simple algorithm that detects and tracks a moving target, and alerts sensor nodes along the projected path of the target. The algorithm involves only simple computation and localizes communication only to the nodes in the vicinity of the target and its projected course. The algorithm has been evaluated on the Berkeley MICA mote testbed using a light source as the moving target. The performance results are presented emphasizing the accuracy of the technique, along with a discussion about our experience in using such a platform for target tracking experiments.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:ad hoc networks routing testbed sensor network
Date of Publication:01/01/2003