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Reliability Experiments for Wireless Sensor Networks in Train Environment
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology. (Mikrovågsteknik)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group. (Signals and systems)
TNT-Elektronik AB, Säter.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microwave and Terahertz Technology. (Mikrovågsteknik)
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2009 (English)In: European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT, 2009, 37-40 p.Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
2009. 37-40 p.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering with specialization in Signal Processing; Engineering Science with specialization in Microwave Technology
Identifiers
URN: urn:nbn:se:uu:diva-120593OAI: oai:DiVA.org:uu-120593DiVA: diva2:303640
Conference
European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT
Projects
WISENET
Available from: 2010-03-15 Created: 2010-03-15 Last updated: 2016-04-14Bibliographically approved
In thesis
1. Wireless Sensor Network and Radio Wave Propagation in Harsh Environments
Open this publication in new window or tab >>Wireless Sensor Network and Radio Wave Propagation in Harsh Environments
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This licentiate thesis cover two important subjects regarding the application of wireless sensor networks (WSNs). Both subjects are related to propagation mechanisms. The first subject is what the radio channel looks like and how it behaves. In this case three different, and extreme, environments are measured and characterized - a train, a half scale jet engine fan and a full scale military jet engine. The train environment is characterized by measure the path loss and fading over distance. For the case with the jet engines, difficulties were found to measure the path loss over distance, so in this case stationary antennas were used, but with the engine running. Each of these shows an extreme type of fading, also known as Rayleigh fading. For the case of jet engine at full speed (about 10 000 rpm), it was shown that the time between two consecutive fading dips where only 290 μs, which is about twice the length of a data package from the WSN involved in this project. The Rayleigh distributed amplitude fading occurs when there is a multipath environment, the radio waves propagate several different paths between the transmitter and receiver, which causes a superposition at the receiver. When having Rayleigh fading, the performance of the radio link is greatly reduced. When applying a WSN in this type of environment, the use of several antennas will improve the received power of the signal. This is done by adding extra antennas to a wireless system and in a clever way combine the signals, or select one of two signals from the antennas. In a book chapter and in a paper presented in the thesis, a new and low energy type of diversity is described. The performance of this new type of diversity is shown by having a two branch diversity and discretely shifting the phase of each branch before combining them. In this case, four relative phase shifts are performed during each symbol received. When performing a combining like this, the energy is saved by not having any decision circuitry. By using this type of diversity and using a 90 % signal reliability and an ideal environment, the diversity gain is 5.5 dB for an averaging detector and 10.3 dB for a peak detector.  The drawback with this system is that it is only limited for systems using simple types of amplitude (ASK) or frequency (FSK) modulation.

Place, publisher, year, edition, pages
Uppsala: Institutionen för teknikvetenskaper, Uppsala universitet, 2012
Keyword
Wireless Sensor Network, WISENET, Wave Propagation, Radio Communication, Harsh Environmnents
National Category
Communication Systems Telecommunications Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Microwave Technology
Identifiers
urn:nbn:se:uu:diva-173479 (URN)
Presentation
2012-05-29, Polhemssalen, Ångströmlaboratioriet, Lägerhyddsvägen 1, Uppsala, 14:15 (English)
Opponent
Supervisors
Projects
WisenetWisejet
Available from: 2012-05-04 Created: 2012-04-25 Last updated: 2012-05-04Bibliographically approved
2. Wireless Sensor Network Systems in Harsh Environments and Antenna Measurement Techniques
Open this publication in new window or tab >>Wireless Sensor Network Systems in Harsh Environments and Antenna Measurement Techniques
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wireless sensor network (WSN) has become a hot topic lately. By using WSN things that previously were difficult or impossible to measure has now become available. One of the main reasons using WSN for monitoring is to save money by cost optimization and/or increase safety by letting the user knowing the physical status of the monitored structure. This thesis considers four main topics, empirical testing of WSN in harsh environments, antenna designs, antenna measurements and radio environment emulation.

The WSN has been tested in train environment for monitoring of ball bearings and inside jet engines to monitor strain of blades and temperatures. In total, two investigations have been performed aboard the train wagon and one in the jet engine. The trials have been successful and provide knowledge of the difficulties with practical WSN applications. The key issues for WSN are robust communication, energy management (including scavenging) and physical robustness.

For the applications of WSN in harsh environments antennas has to be designed. In the thesis, two antennas has been designed, one for train environment and one for the receiver in the jet engine. In the train environment, a more isotropic radiation pattern is preferable; hence a small dual layered patch antenna is designed. The antenna is at the limit of being electrically small; hence slightly lower radiation efficiency is measured. For the WSN in the jet engine, a directive patch array is designed on an ultra-thin and flexible substrate. The thin substrate of the antenna causes rather lower radiation efficiency. But the antenna fulfils the requirements of being conformal and directive.

In reverberation chambers are used to measure antennas, but there are difficulties to provide a realistic radio environment, for example outdoor or on-body. In this thesis, a large reverberation chamber is designed and verified. It enables measurement between 400 MHz and 3 GHz. Also, a sample selection method is designed to provide a post processing possibilities to emulate the radio environment inside the chamber. The method is to select samples from a data set that corresponds to a desired probability density function. The method presented in this thesis is extremely fast but the implementation of the method is left for future research.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 75 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1126
Keyword
Wireless Sensor Network, Antenna, Jet engine, Train, Reverberation chamber, WISENET, Wisejet
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Telecommunications Communication Systems Embedded Systems
Research subject
Engineering Science with specialization in Microwave Technology
Identifiers
urn:nbn:se:uu:diva-218891 (URN)978-91-554-8884-0 (ISBN)
Public defence
2014-04-04, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Projects
WISENETWiseJet
Available from: 2014-03-13 Created: 2014-02-19 Last updated: 2014-04-29

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Grudén, MathiasHallbjörner, PaulRydberg, Anders

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