Title page for ETD etd-12202006-082542

Type of Document

Master's Thesis

Author

Bhatt, Bhushan ,

URN

etd-12202006-082542

Title

Design and Implementation of a distributed scheduling algorithm using period inflation for sensor networks.

Degree

Master of Science

Graduate Program

Computer Networking

Advisory Committee

Advisor Name	Title
Dr. Rudra Dutta	Committee Chair
Dr. Do Young Eun	Committee Member
Dr. Mihail Sichitiu	Committee Member

Keywords

period inflation
adaptive algorithm

Date of Defense

2006-12-18

Availability

unrestricted

Abstract

Wireless Sensor Networks (WSNs) are fast emerging as a new and ubiquitous networking arena which will enables many new applications and pervades many old ones. One of the motivations for the development of WSNs is their ability to be deployed in any environment in a comparatively ad-hoc manner. The most important challenge faced by WSNs is battery-limited lifetime of the network. Physically replacing batteries is infeasible in most real-life deployments of WSNs. It has been demonstrated both theoretically and practically that intelligent operation of WSN nodes can improve network lifetime. For example, turning off wireless transceivers at WSN nodes, minimizing idle listening, can increase battery
lifetimes by large factors, especially in many passive data sensing applications where the
sense-receive-transmit cycle of the sensors is periodic.

In particular, we focus on some previous work in which an adaptive scheduling algorithm was proposed for this purpose, under unpredictable but small clock drift (so called quasi-periodic traffic). While this approach can adapt effectively to unknown transmission
periods and unknown changes in transmission periods, the fundamental problem remains:
a few nodes close to the base station deplete their batteries sooner than the rest resulting
in early network death. Further, this phenomenon reduces the effectiveness of the method
even more when (a) the periods of the various nodes are very disparate, and (b) when
nodes artificially reduce their periods to maintain end-to-end delay bounds. In this thesis,
we advance a new technique called "period inflation", by which the nodes of a WSN can
cooperatively create a schedule in which nodes close to the base station have higher periods.
We investigate the performance of the inflated and non-inflated cases for scenarios where
all nodes have similar periods as well as when some nodes have very disparate periods, and
also under bounded delay conditions. Numerical results show that the new technique of
period in�ation performs better, as expected.

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