The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Media Access Control and Time Synchronization in Delay-Sensitive Multi-Channel Wireless Sensor Networks

Jari Nieminen

Doctoral dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the School of Electrical Engineering for public examination and debate in Auditorium S1 at the Aalto University School of Electrical Engineering (Espoo, Finland) on the 30th of March 2012 at 12 noon.

Overview in PDF format (ISBN 978-952-60-3607-6)   [1078 KB]
Dissertation is also available in print (ISBN 978-952-60-4523-8)

Abstract

Wireless Sensor Networks (WSNs) consist of sensor nodes that measure the environment and one or more gateway nodes that collect the wirelessly sent information from sensor nodes. Wireless systems are free from the constraints of cables while they provide low installation costs, ease of maintenance, and flexibility. Hence, it is natural that WSNs offer an interesting solution for an innumerable number of applications although the exploitation of wireless networks brings new challenges as well because of shared and unreliable transmission media. Improving robustness and efficiency, together with the minimization of communication delays are the most important research challenges en route towards the large-scale implementation of WSNs.

Media Access Control (MAC) protocols are responsible for sharing the transmission media among sensor nodes and avoiding collisions of transmissions. Motivation for the research of multi-channel MAC protocols is due to the fact that the performance of a wireless network can be significantly enhanced using multiple frequency channels simultaneously. Multi-channel communications can be used for minimization of delay which is crucial in delay-sensitive applications, such as in wireless automation and target tracking. Time synchronization is essential for many WSN applications and the use of multi-channel communications enables faster execution of the synchronization process which improves network efficiency. Most current WSNs use unlicensed parts of the frequency spectrum which have become very crowded lately. Cognitive Radio (CR) technology can be used in WSNs to avoid problems related to coexistence with other systems and enable efficient spectrum use.

In this thesis a novel multi-channel MAC protocol is presented that has been designed especially to correspond to the requirements of WSN applications. By means of theoretical analysis it is shown that the proposed protocol outperforms other existing solutions with respect to delay, which is of significant importance for many WSN applications. Impacts of multi-channel communications on wireless automation and target tracking are investigated and the results show the interdependencies between communication and application parameters. In addition to these topics, a novel multi-channel time synchronization protocol is presented and practical issues related to time synchronization in CR networks are studied.

This thesis consists of an overview and of the following 8 publications:

  1. Shekar Nethi, Jari Nieminen, and Riku Jäntti. 2011. Exploitation of multi-channel communications in industrial wireless sensor applications: Avoiding interference and enabling coexistence. In: Proceedings of the 2011 IEEE Wireless Communications and Networking Conference (WCNC 2011). Cancun, Mexico. 28-31 March 2011. IEEE. Pages 345-350. ISBN 978-1-61284-255-4.
  2. Jari Nieminen and Riku Jäntti. 2011. Delay-throughput analysis of multi-channel MAC protocols in ad hoc networks. EURASIP Journal on Wireless Communications and Networking, volume 2011, Special Issue on Quality of Service in Wireless Networks, 108, 15 pages.
  3. Jari Nieminen, Mikael Björkbom, Riku Jäntti, and Lasse Eriksson. Multi-channel communications in wireless automation: Interdependencies between communication and control parameters. International Journal of Distributed Sensor Networks. Accepted for publication, in press, December 2011.
  4. Jari Nieminen, Riku Jäntti, and Jan Eriksson. Performance of target tracking applications in multi-channel wireless sensor networks. In: Proceedings of the 2012 IEEE Wireless Communications and Networking Conference (WCNC 2012). Paris, France. 1-4 April 2012. IEEE. Accepted for publication.
  5. Jari Nieminen, Riku Jäntti, and Lijun Qian. 2009. Time synchronization of cognitive radio networks. In: Mehmet Ulema (editor). Proceedings of the 2009 IEEE Global Telecommunications Conference (GLOBECOM 2009). Honolulu, Hawaii, USA. 30 November - 4 December 2009. IEEE. 6 pages. ISBN 978-1-4244-4148-8.
  6. Jari Nieminen, Lijun Qian, and Riku Jäntti. 2011. Network-wide time synchronization in multi-channel wireless sensor networks. Wireless Sensor Network, volume 3, number 2, pages 39-53.
  7. Jari Nieminen, Riku Jäntti, and Lijun Qian. 2010. Primary user detection in distributed cognitive radio networks under timing inaccuracy. In: Proceedings of the 4th IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN 2010). Singapore. 6-9 April 2010. IEEE. 8 pages. ISBN 978-1-4244-5189-0.
  8. Jari Nieminen, Riku Jäntti, and Lijun Qian. 2010. Suppression of intra-network interference in decentralized cognitive radio networks under timing errors. In: Beata J. Wysocki and Tadeusz A. Wysocki (editors). Proceedings of the 4th International Conference on Signal Processing and Communication Systems (ICSPCS 2010). Gold Coast, Australia. 13-15 December 2010. IEEE. 7 pages. ISBN 978-1-4244-7908-5.

Keywords: media access control, multi-channel communications, time synchronization, wireless sensor networks, cognitive radio networks

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Last update 2012-10-31