My research focuses on sensor networks in harsh environments. The work investigates how environmental factors impact wireless links, showing the importance of understanding the local environment. More recent work includes the use of opportunistic networks for sensor data collection, a communication paradigm often envisioned for harsh environments.
I am in my final year (out of five) of PhD studies at the Department of Information Technology, Uppsala University.
I am a member of the Communications Research group (CoRe ) and part of the Centre for Natural Disaster Science
(CNDS ). As part of my PhD I also spend 20% of my time teaching.
Previosly (2014-2015) I spent a year abroad as a visiting research student in both Australia and Japan. I visited the Networks Research Group at NICTA in Australia with a three month visit to the Dependable Wireless Laboratory at NICT in Japan.
UPDATE!
Publication List
A Node-Link Perspective on the Impact of Local Conditions in Sensor Networks
Hjalmar Wennerström. Doctoral Thesis. September 2016, Uppsala, Sweden. [Link ]
Towards Even Coverage Monitoring with Opportunistic Sensor Networks
Hjalmar Wennerström, Christian Rohner.
IEEE 802.15.4 Channel Diversity in an Outdoor Environment
Atis Elsts, Hjalmar Wennerström, Christian Rohner.
Considering Multi-Contact Encounters in Opportunistic Networks
Hjalmar Wennerström, Christian Rohner, David Smith.
A Game Theoretic Approach to Sensor Data Communications in an Opportunistic Network
Hjalmar Wennerström, David Smith.
Location and Density of Rain Gauges for the Estimation of Spatial Varying Precipitation
Marc Girons Lopez, Hjalmar Wennerström, Lars-Åke Nordén, Jan Seibert.
Meteorological Impact and Transmission Errors in Outdoor Wireless Sensor Networks
Hjalmar Wennerström. Licentiate Thesis . December 2013, Uppsala, Sweden. [Download ]
All is not Lost: Understanding and Exploiting Packet Corruption in Outdoor Sensor Networks
Frederik Hermans, Hjalmar Wennerström, Liam McNamara, Christian Rohner, Per Gunningberg. Best Paper Award!
Hot Packets: A Systematic Evaluation of the Effect of Temperature on Low Power Wireless Transceivers
C.A. Boano, H. Wennerström, M.A. Zúñiga, J. Brown, C. Keppitiyagama, F.J. Oppermann, U. Roedig, L.-Å. Nordén, T. Voigt, and K. Römer. Best Paper Award!
Transmission Errors in a Sensor Network at The Edge of The World
Hjalmar Wennerström, Liam McNamara, Christian Rohner, Lars-Åke Nordén.
A Long-Term Study of Correlations between Meteorological Conditions and 802.15.4 Link Performance
Hjalmar Wennerström, Frederik Hermans, Olof Rensfelt, Christian Rohner, Lars-Åke Nordén.
A Study of Packet Errors on Outdoor 802.15.4 Links
Hjalmar Wennerström, Liam McNamara, Christian Rohner, Lars-Åke Nordén.
A Long-Term Study on the Effects of Meteorological Conditions on 802.15.4 Links
Hjalmar Wennerström, Frederik Hermans, Olof Rensfelt, Christian Rohner, Lars-Åke Nordén.
Natural Disaster Sensor Networks
Hjalmar Wennerström.
Auto-tagging of images in non-english languages using tag language conversion
Keiichiro Hoashi, Hiromi Ishizaki, Hjalmar Wennerström, Yasuhiro Takishima.
Sensor network deployments
Marsta Weather Station, Uppsala, Sweden [map ]
Deployed in April 2012 at the Uppsala University meteorological station in Marsta . The experiment has been running continuously for more than a year, collecting a wide range of link characteristics. The proximity to the meteorological station also provides high-quality environmental data. Some collected data and more information can be found here .
Abisko Scientific Research Station, Abisko, Sweden [map ]
Deployed March 2013 - July 2015 at the Abisko scientific research station as part of the INTERACT project.
The sub-arctic climate, with no sunrise in the winter and no sunset in the summer, creates a unique environment.
Teaching
Wireless Communication and Networked Embedded Systems (10 ECTS)TA in 2012 , 2013 and 2014
Computer Networks 1 (5 ECTS)TA in 2011 , 2012 , 2013 and 2015
Computer Networks and Distributed Systems (10 ECTS)TA in 2015
Computer Networks 2 (10 ECTS)TA in 2012 , 2013 and 2014
Computer Networks 3 (5 ECTS)TA in 2012
Information Technology (10 ECTS)TA in 2012
Education
I received my Master's degree (Civilingenjör) in Information Technology from Uppsala University. During my studies I was a visiting student at both National University of Singapore (NUS ) and Seoul National University (SNU ).
My masters thesis was conducted at KDDI R&D Laboratories in Saitama, Japan. The title of my thesis was "Leveraging Dominant Language Image Tags for Automatic Image Annotation in Minor Languages" (link ).
Contact
email: es.uu.ti@mortsrennew.ramlajh
Office: Ångström building, room 72402
