Series in
Distributed Computing
edited by Roger Wattenhofer
Vol. 16
Philipp Sommer
Wireless Embedded Systems:
Time, Location, and Applications
1st edition /1.
Aufl. 2012, 168 pages/Seiten, € 64,00.
ISBN 3-86628-413-6 and 978-3-86628-413-5
Wireless
embedded systems combine sensors and actuators with processing, storage, and
communication capabilities. Networks of small, lowpower
wireless devices, so called nodes, offer the potential to collect observations
of the physical world at unprecedented fidelity and scale. Time and location
are of fundamental importance in the context of wireless sensor networks.
Accurate time and location information are crucial for many tasks, e.g., sensor
data fusion, spatiotemporal coordination, lowpower
operation, and wireless medium access.
In
the first part of this volume, we study the problem of time synchronization. As
clock sources in wireless embedded systems often exhibit severe drift, and
message exchange is subject to a delay, sophisticated algorithms are mandatory
to keep clocks in synchronization. Existing time synchronization algorithms are
designed to provide networkwide synchronization,
i.e., between arbitrary nodes in the network. However, large synchronization
errors may become visible with increasing distance from a reference node, but
also closeby nodes in a network may be synchronized
poorly. To address these issues, we propose two clock synchronization
protocols: the Gradient Time Synchronization Protocol to achieve local
synchronization, and the PulseSync protocol for
global synchronization. We evaluate the performance of both protocols by
simulations and experiments in different wireless sensor network testbeds.
The
second part of this volume is dedicated to the question how we can provide
accurate location information in the context of wireless embedded systems. We
present the SpiderBat platform, which provides node
localization for sensor nodes using ultrasound pulses. By employing multiple
transmitters and receivers, we can estimate the distance and angle between
neighboring nodes. Using both distance and angle information allows to localize nodes with an accuracy of a few centimeters,
even in sparse networks where other approaches fail.
In
the third part, we discuss design considerations for the architecture of future
wireless embedded systems, as they have evolved from pure research tools to
ubiquitous smart things. To this end, we present a resourceoriented
approach to facilitate the connection between heterogeneous devices and
services, and a novel wearable sensor platform that utilizes mobile phones for
personalized sensing applications.
About the author:
Philipp
Sommer received his degree in electrical
engineering and information technology from ETH Zurich, Switzerland, in 2007.
In the same year he joined the Distributed Computing Group of Professor Roger Wattenhofer at ETH Zurich as a Ph.D. student and research
assistant. In 2011 he received his Ph.D. degree for his work on wireless
embedded systems.
Keywords:
Wireless Embedded Systems
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