Christian Rohner

Christian Rohner

Professor

Mobile networks, wireless security, and energy efficiency

Uppsala University
Department of Information Technology, Box 337, 751 05 Uppsala, Sweden
Ångström Lab, room 72405
+46 70 167 9361
Docent in Computer Science Uppsala University
Dr. sc. tech ETH Zürich
Communication Systems Institut Eurecom
Electrical Engineer ETH Zürich
IBM Zurich Research Lab
Swisscom
Google Scholar

Recent results

Backscatter Communication [ACM SenSys 2017, ACM HotWireless 2017]

There is the long-standing assumption that radio communication in the range of hundreds of meters needs to consume mWs of power at the transmitting device. In this paper, we demonstrate that this is not necessarily the case for some devices equipped with backscatter radios. We present LoRea, an architecture consisting of a tag, a reader and multiple carrier generators that overcomes the power, cost and range limitations of existing systems such as Computational Radio Frequency Identification (CRFID). LoRea achieves this by: (i) generating narrow-band backscatter transmissions that improve receiver sensitivity. (ii) mitigating self-interference without the complex designs employed on RFID readers by keeping carrier signal and backscattered signal apart in frequency. (iii) decoupling carrier generation from the reader and using devices such as WiFi routers and sensor nodes as a source of the carrier signal. LoRea's range scales with the carrier strength, and proximity to the carrier source and achieves a maximum range of 3.4km when the tag is located at 1m distance from a 28dBm carrier source while consuming 70uW at the tag. When the tag is equidistant from the carrier source and the receiver, we can communicate upto 75m, a significant improvement over existing RFID readers.

Battery lifetime in wireless sensor networks [WONS 2014]

We examine sets of periodic loads with the same time-average current, but different load values, duty cycles, and active periods to explore the impact of various load parameters on sensor lifetime. We observe differences in lifetime of as much as 15-20%, suggesting that shorter load durations are associated with longer observed lifetimes, especially high current loads at low duty cycles. Our data show that at low duty cycles, the observed lifetime differs from the lifetime predicted by 260mA-h consumed” models by as much as 260%.

Packet corruption in outdoor wireless sensor networks [EWSN 2014]

During phases of transient connectivity, sensor nodes receive a substantial number of corrupt packets. These corrupt packets are gen- erally discarded, losing the sent information and wasting the energy put into transmitting and receiving. Our analysis of several years of data from an outdoor sensor network deployment shows that packet corruption follows a distinct pattern that is observed on all links. We propose a probabilistic approach to recover information about the original content of a corrupt packet. Our approach vastly reduces the uncertainty about the original content, as measured by a manifold reduction in entropy.

Previous projects

I have large experience from international and national collaboration projects with academic and industry partners, both as principal investigator or lead architect. Some examples include EU/ResumeNet, EU/Haggle, Vinnova/VinnSec, and SSF/Winternet projects.

Students

Lorenzo Corneo

Lorenzo Corneo

Lorenzo started his PhD in February 2017. Lorenzo's main supervisor is Per Gunningberg.
Amin Kaveh

Amin Kaveh

Amin started his PhD in November 2016 with the objective to develop new methods to model, analyze and mine large complex networks. Amin's main supervisor is Matteo Magnani.
Laura Feeney

Laura Feeney

Laura studies energy-efficient wireless systems.
Volkan Cambazoglu

Volkan Cambazoglu

Protocol, Mobility and Adversary Models for the Verification of Security (Licentiate 2016)
Hjalmar Wennerström

Hjalmar Wennerström

A Node-Link Perspective on the Impact of Local Conditions in Sensor Networks (2016)
Fredrik Bjurefors

Fredrik Bjurefors

Opportunistic Networking - Congetsion, Transfer Ordering and Resilience (2014)
Ioana Rodhe

Ioana Rodhe

Secure and Privacy-Aware Data Collection in Wireless Sensor Networks (2012)

I have also had the plesure to work together with Ambuj Varshney, Erik Nordstöm, Oskar Wibling, and Henrik Lundgren.

Publications

Peer-reviewed journal articles

  • Security in Visible Light Communication: Novel Challenges and Opportunities. Ch. Rohner, S. Raza, D. Puccinelli, T. Voigt - Sensors & Transducers Journal, 2015
  • How packet size matters in wireless communications and what to do about it. M. Jacobsson, Ch. Rohner - IEEE Communication Letters, 2015
  • Haggle: Opportunistic Mobile Content Sharing using Search. E. Nordström, Ch. Rohner, P. Gunningberg - Elsevier Computer Communications - Special Issue on Opportunistic Networks, 2014
  • Resilience and Opportunistic Forwarding: Beyond Average Value Analysis. F. Bjurefors, M. Karaliopoulos, Ch. Rohner, P. Smith, G. Theodoropoulos, P. Gunningberg - Elsevier Computer Communications - Special Issue on Opportunistic Networks, 2014
  • Comparing wireless flooding protocols using trace-based simulations. M. Jacobsson, Ch. Rohner - EURASIP Journal on Wireless Communications and Networking, p 169, 2013
  • Leveraging a power save protocol to improve performance in ad hoc networks. L.M. Feeney, Ch. Rohner, B. Ahlgren - In volume 11, issue 2 of SIGMOBILE Mob. Computer Communication. Rev., ACM, New York, 2007
  • DEAPspace - Transient Ad-Hoc Networking of Pervasive Devices. R. Hermann, D. Husemann, M. Moser, M. Nidd, Ch. Rohner, A. Schade - Computer Networks - Special Edition on Pervasive Computing, 2001

Peer-reviewed conference articles

  • Degree in Probabilistic Networks: Revisited A. Kaveh, M. Magnani and Ch. Rohner - Complex Networks, 2017
  • A backscatter architecture that achieves long communication range A. Varshney, O. Harms, C. Perez Penichet, Ch. Rohner, F. Hermans, T. Voigt - ACM Conference on Embedded Networked Sensor Systems (SenSys), 2017
  • Towards Wide-area Backscatter Networks A. Varshney, C. Perez Penichet, Ch. Rohner, T. Voigt - ACM Workshop on Hot Topics in Wireless (HotWireless), 2017
  • Enabling Ambient Backscatter Using a Low-Cost Software Defined Radio M. Stiefel, E. van Rijnswou, C. Perez-Penichet, A. Varshney, Ch. Rohner, T. Voigt - Swedish National Computer Networking Workshop (SNCNW), 2017
  • Towards even coverage monitoring with opportunistic sensor networks H. Wennerström, Ch. Rohner - ACM MobiCom Workshop on Challenged Networks (CHANTS), 2016
  • Focus: Robust Visual Codes for Everyone F. Hermans, L. McNamara, G. Sörös, Ch. Rohner, T. Voigt, E. Ngai - ACM International Conference on Mobile Systems, Applications, and Services (MobiSys), 2016
  • IEEE 802.15.4 Channel Diversity in an Outdoor Environment A. Elst, H. Wennerström, Ch. Rohner - ACM Workshop on Real World Wireless Sensor Networks (RealWSN), 2015
  • Considering Multi-Contact Encounters in Opportunistic Networks H. Wennerström, Ch. Rohner - ACM MobiCom Workshop on Challenged Networks (CHANTS), 2015
  • How do the dynamics of battery discharge affect sensor lifetime? L.M. Feeney, Ch. Rohner, P. Gunningberg, A. Lindgren, L. Andersson - IEEE/IFIP Annual Conference on Wireless On-demand Network Systems and Services (WONS), 2014 - best paper award
  • All is not Lost: Understanding and Exploiting Packet Corruption in Outdoor Sensor Networks. F. Hermans, H. Wennerström, L. McNamara, Ch. Rohner, P. Gunningberg - European Conference on Wireless Sensor Networks (EWSN), 2014 - best paper award
  • Resilience and Opportunistic Forwarding: Beyond Average Value Analysis. F. Bjurefors, M. Karaliopoulos, Ch. Rohner; P. Smith; G. Theodoropoulos; P. Gunningberg - ACM MobiCom Workshop on Challenged Networks (Chants), Miami, 2013
  • Transmission Errors in a Sensor Network at The Edge of The World. H. Wennerström, L. McNamara, Ch. Rohner, L-Å. Nordén - I Proceedings of the 5th Extreme Conference on Communication (ExtremeCom), 2013
  • Evaluating Battery Models in Wireless Sensor Networks. Ch. Rohner, L.M. Feeney, P. Gunningberg - International Conference on Wired/Wireless Internet Communications (WWIC), 2013
  • A Long-Term Study of Correlations between Meteorological Conditions and 802.15.4 Link Performance. H. Wennerström, F. Hermans, O. Rensfelt, Ch. Rohner, L-Å. Nordén - IEEE International Conference on Sensing, Communication, and Networking (SECON), 2013
  • A social node model for realising information dissemination strategies in delay tolerant networks. S. Bastani, B. Landfeldt, Ch. Rohner, P. Gunningberg - ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems (MSWiM), 2012
  • On location privacy and quality of information in participatory sensing. I. Rodhe, Ch. Rohner, E. C.-H. Ngai - ACM Symposium on QoS and Security for Wireless and Mobile Networks (Q2SWinet), 2012
  • The Impact of Trace and Adversary Models on Location Privacy Provided by K-anonymity. V. Cambazoglu, Ch. Rohner, B. Victor - EuroSys Workshop on Measurement, Privacy, and Mobility, 2012
  • Trace-based performance analysis of opportunistic forwarding under imperfect node cooperation M. Karaliopoulos, Ch. Rohner - In Proceedings of the IEEE International Conference on Computer Communications (Infocom), 2012
  • Mining Conversations of Geographically Changing Users. L. McNamara, Ch. Rohner - World Wide Web 2012 Workshop on Social Web for Disaster (SWDM), 2012
  • On Resilience in Opportunistic Networks. M. Mehrparvar, F. Bjurefors, Ch. Rohner, P. Smith - Swedish National Computer Networking Workshop (SNCNW), 2012
  • Making the Most of Your Contacts: Transfer Ordering in Data-Centric Opportunistic Networks. Ch. Rohner, F. Bjurefors, P. Gunningberg, L. McNamara - ACM MobiOpp Workshop on Mobile Opportunistic Networks (MobiOpp), 2012
  • A Long-Term Study on the Effects of Meteorological Conditions on 802.15.4 Links. H. Wennerström, F. Hermans, O. Rensfelt, Ch. Rohner, L-Å Nordén - Swedish National Computer Networking Workshop (SNCNW), 2012
  • Haggle Testbed: a Testbed for Opportunistic Networks. F. Bjurefors, P. Gunningberg, Ch. Rohner - Swedish National Computer Networking Workshop (SNCNW), 2011
  • Congestion Avoidance in a Data-Centric Opportunistic Network. F. Bjurefors, P. Gunningberg, Ch. Rohner, S. Tavakoli - ACM SIGCOMM Workshop on Information-Centric Networking (ICN), 2011
  • Privacy-aware probabilistic sampling for data collection in wireless sensor networks. J. Guerreiro, E. C.-H. Ngai, Ch. Rohner - International Wireless Communications and Mobile Computing Conference, 2011
  • Twitter in Disaster Mode: Security Architecture. T. Hossmann, P. Carta, D. Schatzmann, F. Legendre, P. Gunningberg, Ch. Rohner - CoNEXT Special Workshop on the Internet and Disasters (SWID), 2011
  • Twitter in Disaster Mode: Opportunistic Communication and Distribution of Sensor Data in Emergencies. T. Hossmann, F. Legendre, P. Carta, P. Gunningberg, Ch. Rohner - ExtremeCom, 2011 - best paper award
  • Lower trees with fixed degrees: a recipe for efficient secure hierarchical aggregation in WSNs. D. Sutic, I. Rodhe, Ch. Rohner, B. Victor - IEEE Wireless Communications and Networking Conference (WCNC), 2011
  • Interest dissemination in a searchable data-centric opportunistic network F. Bjurefors, P. Gunningberg, E. Nordström, Ch. Rohner - European Wireless Conference, 2010 - Invited paper
  • Secure Overlays: Making Static Key Distribution Schemes Work with Mobile Base Stations in WSNs I. Rodhe, Ch. Rohner - International Conference on Wired/Wireless Internet Communications (WWIC), 2010
  • On realising a strategy for resilience in opportunistic networks M. Schöller, P. Smith, Ch. Rohner, M. Karaliopoulos, A. Jabbar, J. P. G. Sterbenz, D. Hutchinson - Future Network and Mobile Summit, 2010
  • Haggle: A Data-centric Network Architecture for Mobile Devices E. Nordström, P. Gunningberg, Ch. Rohner - ACM International Symposium on Mobile Ad Hoc Networking and Computing: Mobihoc Wireless S3 Workshop, 2009 - best presentation award
  • A study of the message complexity for integrity preserving aggregation schemes used in wireless sensor networks I. Rodhe, Ch. Rohner - Swedish National Computer Networking Workshop (SNCNW), 2009
  • Presentation of the VINN Excellence Center for Wireless Sensor Networks (WISENET) A. Ahlén, B. Ahlgren, R. Grönros, P. Gunningberg, K. Hjort, I. Katardijev, Ch. Rohner, A. Rydberg - Conference on Radio Science (RVK), 2008
  • n-LDA: n-Layers Data Aggregation in Sensor Networks I. Rodhe, Ch. Rohner - IEEE International Workshop on Wireless Security and Privacy (WiSP), 2008
  • n-LQA: n-Layers Query Authentication in Sensor Networks I. Rodhe, Ch. Rohner, A. Achtzehn - IEEE International Workshop on Wireless and Sensor Networks Security (WSNS), 2007
  • ARPD: Asynchronous random key pre-distribution in the LEAP framework for Wireless Sensor Networks A. Achtzehn, Ch. Rohner, I. Rodhe - IEEE International Workshop on Wireless and Sensor Networks Security (WSNS), 2007
  • Evaluating Wireless Multi-hop Networks Using a Combination of Simulation, Emulation, and Real World Experiments E. Nordström, P. Gunningberg, Ch. Rohner, O. Wibling - International Workshop on System Evaluation for Mobile Platforms (MobiEval), 2007
  • The impact of wakeup schedule distribution in asynchronous power save protocols on the performance of multihop wireless networks. L.M. Feeney, Ch. Rohner, B. Ahlgren - IEEE Wireless Communications and Networking Conference (WCNC), 2007
  • Testbed and Methodology for Experimental Evaluation of Opportunistic Networks. F. Bjurefors, K. Phanse, O. Wibling, Ch. Rohner - Scandinavian Workshop on Wireless Ad-hoc Networks (AdHoc), 2007
  • Verifiable Agreement: Limits of Non-Repudiation in Mobile Peer-to-Peer Ad Hoc Networks. Z. Benenson, F.C. Freiling, B. Pfitzmann, Ch. Rohner, M. Waidner - European Workshop on Security and Privacy in Ad hoc and Sensor Networks, 2006
  • Implementing Agreement Protocols in Sensor Networks. A. Achtzehn, Z. Benenson, Ch. Rohner - International Workshop on Wireless and Sensor Networks Security (WSNS), 2006
  • Modeling Capacity in Ad Hoc Networks: Extended Abstract. L.M. Feeney, Ch. Rohner - ACM/IEEE International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems (MSWiM), 2006
  • A model for evaluating asynchronous protocols in Ad hoc Networks. L.M. Feeney, Ch. Rohner - Scandinavian Workshop on Wireless Ad-hoc Networks (AdHoc), 2006.
  • Comparing Simulation, Emulation, and Real-World Experimental Results in Mobile Ad hoc Networks. E. Nordström, O. Wibling, Ch. Rohner, P. Gunningberg - Proceedings of the 6th Scandinavian Workshop on Wireless Ad-hoc Networks (AdHoc), 2006
  • Interactions between TCP, UDP and Routing Protocols in Wireless Multi-hop Ad hoc Networks. Ch. Rohner, E. Nordström, P. Gunningberg, Ch. Tschudin - Proceedings of the 1st IEEE ICPS Workshop on Multi-hop Ad hoc Networks: from theory to reality (REALMAN), 2005
  • Interaction between TCP and UDP flows in Wireless Multi-hop Ad hoc Networks. E. Nordström, Ch. Rohner, P. Gunningberg - Proceedings of the 5th Scandinavian Workshop on Wireless Ad-hoc Networks (Adhoc), 2005
  • Building Secure Communities in Spontaneously Networked Environments. Ch. Rohner - 4th Scandinavian Workshop on Wireless Ad-hoc Networks (AdHoc), 2004
  • Security Bootstrapping for Networked Devices. Ch. Rohner - Swedish National Workshop on Computer Networks, 2003
  • DEAPspace: transient ad-hoc networking of pervasive devices. R. Herman, D. Husemann, M. Moser, M. Nidd, Ch. Rohner, A. Schade - ACM International Symposium on Mobile Ad Hoc Networking and Computing, MobiHoc, 2000

Technical reports

  • A Search-based Network Architecture for Mobile Devices. E. Nordström, P. Gunningberg, Ch. Rohner - Uppsala University IT Technical Reports, ISSN 1404-3203; 2009-003, 2009
  • A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks. E. Nordström, P. Gunningberg, Ch. Rohner, O. Wibling - Uppsala University IT Technical Reports, ISSN 1404-3203; 2007-016, 2007
  • A comprehensive comparison of manet routing protocols in simulation, emulation and the real world. E. Nordström, P. Gunningberg, Ch. Rohner, O. Wibling - Uppsala University IT Technical Reports 2006-012; 2006

Review articles, book chapters, books

  • ARPD: Asynchronous random key predistribution in the LEAP framework for Wireless Sensor Networks. A. Achtzehn, Ch. Rohner, I. Rodhe- in Z. Jiang, Y.Pan (editors), From Problem to Solution: Wireless Sensor Networks Security, ISBN: 978-1-60456-458-0, 2008
  • Proceedings of the REALWSN'05: Workshop on Real-World Wireless Sensor Networks. T. Voigt, Ch. Rohner, A. Dunkels, editors, 2005

Open access computer programs

  • Haggle - A content-centric network architecture for opportunistic communication. Implementation of the Haggle architecture for which I was lead architect and developer together with Erik Nordström. The code runs on a variety of platforms: Android, iOS, Linux, Mac OS, Windows. This work was supported by the european commission.
    Google Code | Google Play
  • PhotoShare for Haggle. Android photo sharing application using Haggle as communication service
    Google Play

Demos

Demonstrations of our system design and experimental research with mobile devices. I am proud of this work because it shows that our ideas actually work. There are years of hard work behind at least the first two listed demos. The venues are first tier conferences with a competitive demo selection process:
  • LoRea: A Backscatter Architecture that Achieves a Long Communication Range: Demo. A. Varshney, C. Perez Penichet, Ch. Rohner, T. Voigt - ACM Sensys, 2017
  • Using Search to Enhance Picture Sharing with Mobile Phones: Demo. E. Nordström, D. Aldman, F. Bjurefors, Ch. Rohner - ACM MobiSys, 2009
  • Search-Based Picture Sharing With Mobile Phones. E. Nordström, Ch. Rohner, F. Bjurefors, D. Aldman - ACM MobiHoc, 2009 - second best demo award
  • Sense the Key: Key Management for Mobile Devices. Ch. Rohner, F. Bjurefors, H. Andersson - ACM International Conference on Mobile Systems, Applications, and Services (ACM MobiSys), 2006
  • Using Ad-hoc Networking in Orienteering - A Demonstration. Ch. Rohner, H. Lundgren, E. Nordström - International Conference on Mobile Computing and Networking (ACM MobiCom), 2004

Conferences

TPC Sensor Networks/Ad-hoc

  • MASS 2014
  • DCOSS 2017, 2013-2014
  • EWSN 2007-2008
  • VTC 2009
  • REALWSN 2015, 2010, 2008, 2006, 2005 (chair)
  • REALMAN 2005-2006
  • SNCNW 2012, 2011
  • AdHoc 2008 (chair)

TPC Opportunistic/Autonomic Networks

  • CHANTS 2012
  • MOBIOPP 2012, 2010, 2007
  • PerMobi 2014
  • AOC 2008-2016
  • MobiHeld 2009
  • AWN 2009

TPC Security/Resilience

  • Globecom Security Track 2015
  • CISS 2014
  • WNR 2011 (chair)
  • MSN, security track 2006
  • SESOC 2010-2014
  • NordSec 2012
  • SOSOC 2008

Local Organiser

  • EWSN 2017
  • SWITS 2014
  • MobiSys 2006
  • REALWSN 2006

Journal Reviewer

  • IEEE Transactions on Mobile Computing
  • IEEE Transactions on Computers
  • Elsevier Computer Communications
  • Elsevier Computer Networks
  • Elsevier Ad hoc Networks