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  • 1. Achtzehn, Andreas
    et al.
    Benenson, Zinaida
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Datorteknik. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Implementing Agreement Protocols in Sensor2006In: The Second International Workshop on Wireless and Sensor Networks Security (WSNS'06), 2006Conference paper (Refereed)
    Abstract [en]

    We investigate application of agreement protocols tolerating malicious failures in sensor networks. We identify several scenarios where agreement can be used, and report on our experience with implementing an agreement protocol.

  • 2.
    Achtzehn, Andreas
    et al.
    RWTH Aachen.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rodhe, Ioana
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    ARPD: Asynchronous random key predistribution in the LEAP framework for Wireless Sensor Networks2007In: 3rd IEEE International Workshop on Wireless and Sensor Networks Security (IEEE WSNS 2007), 2007Conference paper (Refereed)
    Abstract [en]

    In the LEAP framework for wireless sensor networks a set of keys is used to secure communication. LEAP distinguishes between unicast (pairwise) communication, group (cluster) communication and global (broadcast) communication. The keys used in pairwise communication are derived from an initial key KI that nodes are equipped with prior to deployment

    and that is deleted after link setup. Further keys are distributed encrypted with these pairwise keys. If the initial key is ever disclosed, the whole network is compromised.

    To lower the threat of KI disclosure, we present a novel KI -less scheme for key predistribution. Our scheme is based on random key redistribution, and proves to perform better in medium sized networks than previous proposals. It is resilient against node capture attacks and allows node to node authentication. Attacks against overlying protocols in the network are more difficult with this scheme.

    We have conducted computations to show the feasibility of our scheme for networks up to a size of 1000 nodes. By introducing a key reuse system we are able to increase the probability of a successful link setup. We have included a security analysis that discusses our scheme’s resistance against commonly known attacks.

  • 3.
    Ahlén, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Ahlgren, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Grönroos, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Presentation of the VINN Excellence Center for Wireless Sensor Networks (WISENET)2008In: Conference on Radio Science (RVK08), Växjö, 2008Conference paper (Refereed)
  • 4.
    Bastani, Saeed
    et al.
    The University of Sydney.
    Landfeldt, Björn
    Lund University.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A social node model for realising information dissemination strategies in delay tolerant networks2012In: Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems, New york: ACM Press, 2012, p. 79-88Conference paper (Refereed)
    Abstract [en]

    In Delay Tolerant Networks (DTNs) as an emerging content dissemination platform, mobile nodes opportunistically exchange content as they meet, with the intent of disseminating content among nodes that share common interests. During a meeting, nodes can exchange both content of direct interest to themselves as well as content that is of interest to a larger set of nodes that may be encountered in the future. The utility of DTN is governed by the content exchange opportunity (the amount of content that can be exchanged during a meeting) as well as the selection of content to be exchanged in order to maximise the interest nodes will have in information they are exposed to. Considering that there is a cost associated with the content exchange (e.g. battery usage, buffer occupancy or consumed transmission opportunity) the aim for nodes participating in content dissemination should be to maximise their payoff. In this paper, we contribute a generic framework for describing the characteristics of content exchange among participating nodes in a network. We incorporate a distributed information popularity measurement and the pairwise interaction of nodes modelled as a bargaining problem. The outcome of this process is the fair split up of dwelling time as a network resource and the selection of which content objects to exchange in order to maximise the nodes’ payoff. The framework is generally intended to be used as a capstone for investigation of content dissemination properties and various content exchange strategies in a DTN, a topic addressed in this paper and experiments conducted to validate the function and correctness of the proposed framework. 

  • 5.
    Beneson, Zinaida
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Freiling, Felix C.
    Pfitzmann, Birgit
    Rohner, Christian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Waidner, Michael
    Verifiable Agreement: Limits of Non-Repudiation in Mobile Peer-to-Peer Ad Hoc Networks2006In: Third European Workshop on Security and Privacy in Ad hoc and Sensor Networks, 2006Conference paper (Refereed)
    Abstract [en]

    We introduce verifiable agreement as a fundamental service for securing mobile peer-to-peer ad hoc networks, and investigate its solvability. Verifiability of a protocol result means that the participants can prove that the protocol reached a particular result to any third party (the verifier) which was not present in the network at the time of the protocol execution.

  • 6.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nordström, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Interest dissemination in a searchable data-centric opportunistic network2010In: Proc. European Wireless Conference: EW 2010, Piscataway, NJ: IEEE , 2010, p. 889-895Conference paper (Other academic)
  • 7.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Haggle Testbed: a Testbed for Opportunistic Networks2011In: In Proceedings of the 7th Swedish National Computer Networking Workshop, 2011Conference paper (Refereed)
  • 8.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Tavakoli, Sam
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Congestion Avoidance in a Data-Centric Opportunistic Network2011In: Proceedings of the 2011 ACM SIGCOMM Workshop on Information-Centric Networking (ICN-2011), 2011Conference paper (Refereed)
  • 9.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Karaliopoulos, Markourios
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Smith, Paul
    Theodoropoulos, George
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Resilience and Opportunistic Forwarding: Beyond Average Value Analysis2014In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 48, no SI, p. 111-120Article in journal (Refereed)
    Abstract [en]

    Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of highly heterogeneous, and not always software and hardware-compatible, user nodes. Moreover, the absence of central coordination and control makes them vulnerable to malicious attacks. In this paper, we study the resilience of popular forwarding protocols to a representative set of challenges to their normal operation. These include jamming locally disturbing message transfer between nodes, hardware/software failures and incompatibility among nodes rendering contact opportunities useless, and free-riding phenomena. We first formulate and promote the metric envelope concept as a tool for assessing the resilience of opportunistic forwarding schemes. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated challenge impact due to node heterogeneity (device capabilities, mobility) and attackers’ intelligence. We then propose heuristics to generate worst- and best-case challenge realization scenarios and approximate the lower and upper bounds of the metric envelopes. Finally, we demonstrate the methodology in assessing the resilience of three popular forwarding protocols in the presence of the three challenges, and under a comprehensive range of mobility patterns. The metric envelope approach provides better insights into the level of protection path diversity and message replication provide against different challenges, and enables more informed choices in opportunistic forwarding when network resilience becomes important.

  • 10.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Karaliopoulos, Merkourios
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Smith, Paul
    Theodoropoulos, George
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Resilience and Opportunistic Forwarding: Beyond Average Value Analysis2013In: CHANTS '13 Proceedings of the 8th ACM MobiCom workshop on Challenged networks, 2013Conference paper (Refereed)
    Abstract [en]

    Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of heterogeneous, and not always software- and hardware-compatible user nodes. Moreover, the absence of central control makes them vulnerable to malicious attacks. In this paper, we take a fresh look at the resilience of opportunistic forwarding to these challenges. In particular, we introduce and promote the use of metric envelopes as a resilience assessment tool. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated impact that a challenge may have on the forwarding performance due to node heterogeneity (device capabilities, mobility) and attackers’ intelligence. The use of metric envelopes is demonstrated in the case of three challenges: jamming, hardware/software failures and incompatibilities, and free-riding phenomena. For each challenge, we first devise heuristics to generate worst- and best-case realization scenarios that can approximate the metric envelopes. Then we derive the envelopes of common performance metrics for three popular forwarding protocols under a comprehensive range of mobility patterns. The metric envelope approach enables more informed choices in opportunistic forwarding whenever network resilience considerations become important. 

  • 11.
    Bjurefors, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Phanse, Kaustubh
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wibling, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Testbed and Methodology for Experimental Evaluation of Opportunistic Networks2007In: 7th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'07), 2007Conference paper (Refereed)
  • 12.
    Cambazoglu, Volkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Towards adaptive zero-knowledge protocols: A case study with Fiat–Shamir identification protocol2013In: Proc. 9th Swedish National Computer Networking Workshop, 2013, p. 67-70Conference paper (Refereed)
    Abstract [en]

    Interactive zero-knowledge protocols are used as identification protocols. The protocols are executed in rounds, with security being increased with every round. This allows for a trade-off between security and performance to adapt the protocol to the requirements of the scenario. We experimentally investigate the Fiat–Shamir identification protocol on machines and networks with different performance characteristics. We find that the delay of the protocol highly depends on network latency and upload bandwidth. Computation time becomes more visible, when the protocol transmits little amount of data via a low latency network. We also experience that the impact of the sizes of the variables on the delay of the protocol is less than the number of rounds', which are interior factors in the protocol.

  • 13.
    Cambazoglu, Volkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Victor, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    The impact of trace and adversary models on location privacy provided by K-anonymity2012In: Proc. 1st Workshop on Measurement, Privacy, and Mobility, New York: ACM Press, 2012, article id 6Conference paper (Refereed)
  • 14.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hartung, Robert
    Technische Universitaet Braunschweig.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kulau, Ulf
    Technische Universitaet Braunschweig.
    Wolf, Lars
    Technische Universitaet Braunschweig.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Towards realistic lifetime estimation in battery-powered IoT devices2017Conference paper (Refereed)
    Abstract [en]

    We describe a testbed for studying battery discharge behavior andthe lifetime of wireless devices under controlled temperature conditions and present preliminary measurement results.

  • 15.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A model for evaluating asynchronous protocols in Ad hoc Networks2006In: 6th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'06), 2006Conference paper (Refereed)
  • 16.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Modeling Capacity in Ad Hoc Networks: Extended Poster Abstract2006In: : Poster Session Proceedings, 2006Conference paper (Refereed)
    Abstract [en]

    We describe a simple network model for efficiently simulating the CBR flow capacity of a multi-hop wireless network. The model is particularly intended for studying the behavior of asynchronous protocols, particularly power save protocols, where it is useful to examine many scheduling variations as well as many topologies and network configurations.

    We describe our experience using the model in some experiments in which we examine how the network performance is sensitive to the timing to scheduling variations induced by the operation of a simple power save protocol. We note that the model also seems seems suitable for combinatoric and probabilistic analysis, which is on-going work.

  • 17.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Poster abstract: The feasibility of leveraging a power save protocol to improve performance in ad hoc networks2006In: The Twelfth Annual International Conference on Mobile Computing and Networking (Mobicom2006), 2006Conference paper (Refereed)
    Abstract [en]

    We discuss how the operation of an asynchronous power save protocol affects the scheduling of transmissions in an ad hoc network. We present simulation results that show that network capacity is sensitive to the random distribution of wakeup schedules. Finally, we discuss the implications of this result with respect to improving performance and speculate about potential new cross-layer architectures.

  • 18.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ahlgren, Bengt
    Leveraging a power save protocol to improve performance in ad hoc networks2007In: ACM SIGMOBILE Mobile Computing and Communications Review, ISSN 1559-1662, Vol. 11, no 2, p. 51-52Article in journal (Refereed)
    Abstract [en]

    Power save protocols reduce energy consumption in ad hoc and sensor networks by allowing nodes to put their network interface into a low power consumption sleep state. The power save protocol must allow neighboring nodes to establish intervals during which they are mutually awake and available to exchange traffic. Many such protocols are based on a coordinated election of a covering set that is responsible for buffering traffic for sleeping nodes, but uncoordinated (i.e. asynchronous) protocols have also proven an attractive option.

  • 19.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Datorteknik. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ahlgren, Bengt
    The impact of wakeup schedule distribution in asynchronous power save protocols on the performance of multihop wireless networks2007In: IEEE Wireless Communications and Networking Conference: WCNC 2007, 2007Conference paper (Refereed)
  • 20.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Making batteries a first class element in the design and evaluation of embedded wireless systems2017In: Proc. 14th International Conference on Embedded Wireless Systems and Networks, ACM Digital Library, 2017, p. 242-243Conference paper (Refereed)
  • 21.
    Feeney, Laura Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Lindgren, Anders
    Andersson, Lars
    How do the dynamics of battery discharge affect sensor lifetime?2014In: 2014 11th Annual Conference on Wireless On-demand Network Systems and Services (WONS), Piscataway, NJ: IEEE , 2014, p. 49-56Conference paper (Refereed)
  • 22. Guerreiro, João
    et al.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Privacy-aware probabilistic sampling for data collection in wireless sensor networks2011In: Proc. 7th International Wireless Communications and Mobile Computing Conference, Piscataway, NJ: IEEE conference proceedings, 2011, p. 314-319Conference paper (Refereed)
    Abstract [en]

    The rising popularity of web services and their applications to sensor networks enables real-time data collection and queries by users. Unlike traditional periodic data collection, the traffic patterns generated from real-time data collection may expose the interests of users or the locations of unusual events to the attackers. To provide privacy in data collection, we propose a novel probabilistic sampling mechanism that can hide user queries and unusual events in the network, while supporting both routine and on-demand data reporting. Our goal is to prevent attackers from locating the unusual events and identifying interests of users by eavesdropping and analyzing the network traffic. In our probabilistic sampling scheme, the data are carefully reported at random times in order to mask the unusual events and user queries. In the meantime, our scheme can provide users with high data accuracy at minimized communication overheads. Extensive simulations have been conducted to evaluate the security strength, data accuracy and communication overheads of the proposed scheme.

  • 23.
    Hermans, Frederik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    McNamara, Liam
    Sörös, Gábor
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    FOCUS: Robust visual codes for everyone2016In: Proc. 14th International Conference on Mobile Systems, Applications, and Services, New York: ACM Press, 2016, p. 319-332Conference paper (Refereed)
  • 24.
    Hermans, Frederik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    McNamara, Liam
    Swedish Institute of Computer Science.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Supporting Heterogeneous LCD/Camera Links2014In: Proc. 13th International Symposium on Information Processing in Sensor Networks, Piscataway, NJ: IEEE Press, 2014, p. 289-290Conference paper (Refereed)
  • 25.
    Hermans, Frederik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wennerström, Hjalmar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    McNamara, Liam
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    All is not lost: Understanding and exploiting packet corruption in outdoor sensor networks2014In: Wireless Sensor Networks: EWSN 2014, Springer Berlin/Heidelberg, 2014, p. 116-132Conference paper (Refereed)
  • 26.
    Hilmia, Abdalah
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hewage, Kasun
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Varshney, Ambuj
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. SICS, Stockholm, Sweden.
    Poster Abstract:BouKey: Location-Based Key Sharing Using Visible LightCommunication2016Conference paper (Refereed)
    Abstract [en]

    Visible Light Communication (VLC) is an emerging communication channel serving as a complement to traditional wireless communication. Visible light has many advantages over other communication channels like its inability to penetrate opaque objects. Securely sharing secret keys is a known problem in computer security. Sharing security keys using Radio Frequency (RF) communication is prone to sniffing attacks. In this paper, we introduce a system called BouKey which uses visible light to share keys. This makes BouKey immune to through the wall sniffing attacks. BouKey divides the key and shares it using multiple transmission bulbs allowing the key to be received in a specific area only. Our initial results show that the characteristics and height of the receiver, as well as the transmission angle play a key role in determining the shape and size of this area.

  • 27.
    Hossmann, Theus
    et al.
    ETH Zürich.
    Carta, Paolo
    ETH Zürich.
    Schatzmann, Dominik
    ETH Zürich.
    Legendre, Franck
    ETH Zürich.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Twitter in Disaster Mode: Security Architecture2011In: Conference on emerging Networking EXperiments and Technologies (CoNEXT): Special Workshop on the Internet and Disasters (SWID), Tokyo: ACM Press, 2011Conference paper (Refereed)
    Abstract [en]

    Recent natural disasters (earthquakes, floods, etc.) have shown that people heavily use platforms like Twitter to communicate and organize in emergencies. However, the fixed infrastructure supporting such communications may be temporarily wiped out. In such situations, the phones’ capabilities of infrastructure-less communication can fill in: By propagating data opportunistically (from phone to phone), tweets can still be spread, yet at the cost of delays.

    In this paper, we present Twimight and its network security extensions. Twimight is an open source Twitter client for Android phones featured with a “disaster mode”, which users enable upon losing connectivity. In the disaster mode, tweets are not sent to the Twitter server but stored on the phone, carried around as people move, and forwarded via Bluetooth when in proximity with other phones. However, switching from an online centralized application to a dis- tributed and delay-tolerant service relying on opportunistic communication requires rethinking the security architecture. We propose security extensions to offer comparable security in the disaster mode as in the normal mode to protect Twimight from basic attacks. We also propose a simple, yet efficient, anti-spam scheme to avoid users from being flooded with spam. Finally, we present a preliminary empirical performance evaluation of Twimight. 

  • 28.
    Hossmann, Theus
    et al.
    ETH Zürich.
    Legendre, Franck
    ETH Zürich.
    Carta, Paolo
    ETH Zürich.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Twitter in Disaster Mode: Opportunistic Communication and Distribution of Sensor Data in Emergencies2011In: ExtremeCom2011, ACM Press, 2011Conference paper (Refereed)
    Abstract [en]

    Recent events (earthquakes, floods, etc.) have shown that users heavily rely on online social networks (OSN) to communicate and organize during disasters and in their aftermath. In this paper, we discuss what features could be added to OSN apps for smart phones – for the example of Twitter – to make them even more useful for disaster situations. In particular, we consider cases where the fixed communication infrastructure is partially or totally wiped out and propose to equip regular Twitter apps with a disaster mode. The disaster mode relies on opportunistic communication and epidemic spreading of Tweets from phone to phone. Such “disaster-ready” applications would allow to resume (although limited) communication instantaneously and help distressed people to self-organize un- til regular communication networks are functioning again, or, temporary emergency communication infrastructure is installed.

    We argue why we believe that Twitter with its simplicity and versatile features (e.g., retweet and hashtag) is a good platform to support a variety of different situations and present Twimight, our disaster ready Twitter application. In addition, we propose Twimight as a platform for disseminating sensor data providing information such as locations of drinkable water sources. Eventually, we propose to rely on interest matching to scale Twitter hashtag-based searches in an opportunistic environment. The combination of these features make our opportunistic Twitter the ideal emergency kit in situations of disasters. We discuss and define the main implementation and research challenges (both technical and non- technical). 

  • 29.
    Jacobsson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Comparing wireless flooding protocols using trace-based simulations2013In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, p. 169:1-15Article in journal (Refereed)
    Abstract [en]

    Most wireless multi-hop networks, such as ad hoc networks and wireless sensor networks, need network-wide broadcasting, which is best done with a flooding protocol. In this article, we use packet trace information from a real test-bed network to define a simulator for flooding protocol performance studies. Five protocols are compared using the simulator. Trace-based simulations promise to have the benefits of the simulator, such as reducing required work effort and repeatability but still produce results close to the real test-bed or deployment. We propose and evaluate different approaches on how to use collected trace data and how to tune the parameters to achieve the best possible accuracy in comparison with actual test-bed measurements. We study the resulting accuracy of the model so that performance studies know with what confidence a certain conclusion can be made. Using the new trace-based model and knowing its accuracy, we compare the five flooding protocols to gain additional insights into their performance. Finally, by modifying the trace data, we study how real-world effects, such as links with in-between qualities and asymmetric links, influence the different flooding protocols.

  • 30.
    Jacobsson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Estimating packet delivery ratio for arbitrary packet sizes over wireless links2015In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, no 4, p. 609-612Article in journal (Refereed)
    Abstract [en]

    Real life measurements show that on a given wireless link, the packet delivery ratio of different packet lengths varies with longer packets experiencing lower delivery ratios. In this letter, we measure this effect in detail over several different wireless links and technologies. Our results show that the current models are not entirely correct. Hence, we propose a simple modification that rectifies this behavior. Using this new model, we look at how link quality estimation methods can be enhanced to include this modification. Our study shows that the use of two different packet lengths or simple compensation can be used to achieve significantly better estimation of link quality.

  • 31.
    Karaliopoulos, Merkourios
    et al.
    National and Kapodistrian University of Athens.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Trace-based performance analysis of opportunistic forwarding under imperfect node cooperation2012In: Proceedings of the 31st Annual IEEE International Conference on Computer Communications (IEEE INFOCOM 2012), Orlando: IEEE Communications Society, 2012Conference paper (Refereed)
    Abstract [en]

    The paper proposes an innovative method for the performance analysis of opportunistic forwarding protocols over files logging mobile node encounters (contact traces). The method is modular and evolves in three steps. It first carries out contact filtering to isolate contacts that constitute message forwarding opportunities for given message coordinates and forwarding rules. It then draws on graph expansion techniques to capture these forwarding contacts into sparse space-time graph constructs. Finally, it runs standard shortest path algorithms over these constructs and derives typical performance metrics such as message delivery delay and path hopcount. The method is flexible in that it can easily assess the protocol operation under various expressions of imperfect node cooperation. We describe it in detail, analyze its complexity, and evaluate it against discrete event simulations for three representative randomized forwarding schemes. The match with the simulation results is excellent and obtained with run times up to three orders of size smaller than the duration of the simulations, thus rendering our method a valuable tool for the performance analysis of opportunistic forwarding schemes. 

  • 32.
    Marti, Sergio Angel
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Rohner, Christian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Wireless Communication in Orienteering2005Report (Other (popular scientific, debate etc.))
  • 33.
    McNamara, Liam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Mining Conversations of Geographically Changing Users2012In: Proceedings of the World Wide Web 2012 Workshop on Social Web for Disaster (SWDM2012), Lion, 2012Conference paper (Refereed)
    Abstract [en]

    In recent disaster events, social media has proven to be an effective communication tool for affected people. The corpus of messages contains valuable information about the situation on the ground, needs, and locations of victims. We propose a methodology to extract significant aspects of user discussions to better inform responders and enable an appropriate response.

    The methodology combines location/movement based selection of user together with text mining (term frequency inverse document frequency) to identify important topics of conversation in a dynamic geographic network. We further suggest that both topics and movement patterns change during a disaster, which further allows for identification of new trends.

    When applied to an area where a disaster has recently occured this approach can provide useful insights into where people are located, where they are going and what they saying during those movements. 

  • 34.
    Mehrparvar, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bjurefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Smith, Paul
    AIT Austrian Institute of Technology.
    On Resilience in Opportunistic Networks2012In: 8th Swedish National Computer Networking Workshop SNCNW 2012, 2012Conference paper (Refereed)
  • 35.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aldman, Daniel
    Bjurefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Using Search to Enhance Picture Sharing with Mobile Phones: Demo2009In: ACM MobiSys, Krakow: ACM , 2009Conference paper (Refereed)
  • 36.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Search-based Network Architecture for Content-oriented and Opportunistic CommunicationArticle in journal (Refereed)
    Abstract [en]

    It is well recognized that the current Internet architecture does not properly accommodate content oriented and opportunistic communication. A key to supporting such communication is access to networking primitives that allow temporal and spatial decoupling between senders and receivers. In this paper we present Haggle, a clean slate architecture that is designed from the ground up with such primitives in mind. Haggle rids itself of the traditional layered namespaces and instead introduces a unified and expressive metadata namespace that spans, not only hosts and file systems, but also networks.

    This unified metadata namespace enables resolution through Google-inspired searching, allowing flexible and late binding between content and receivers. We define a set of networking primitives around search based resolution and describe how they provide novel solutions to many problems associated with the targeted scenarios. We describe our architecture and reference implementation that illustrate the feasibility of our approach.

     

  • 37.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Search-based Network Architecture for Mobile Devices2009Report (Other academic)
  • 38.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Haggle: A Data-centric Network Architecture for Mobile Devices2009Conference paper (Other academic)
    Abstract [en]

    Delay-tolerant and opportunistic networks relax the traditional assumption of end-to-end connectivity. Such networks are therefore suitable for content dissemination in sparsely connected regions of the world, and for complementing existing infrastructure by operating cost-free, high bandwidth, albeit high latency, content delivery services.

    In this work we argue, however, that content dissemination in the above contexts requires us to revisit delay-tolerant communication at the architectural level, looking at multiple issues such as naming and addressing, congestion control and application interfaces. We propose a new architecture, called Haggle, that leverages the principles of search, as known from desktop operating systems and the Web, in order to achieve truly data-centric communication. Searching is naturally data-centric and embeds principles, such as ranking, that can be used to bind data to interested receivers and to prioritize the data to send during node encounters. We herein give an overview of the Haggle architecture and its basic design.

  • 39.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wibling, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Cross-Environment Study of Routing Protocols for Wireless Multi-hop NetworksManuscript (Other academic)
  • 40.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wibling, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks2007Report (Other academic)
    Abstract [en]

    We study ad hoc routing protocol mechanisms that impact the performance during and after periods of connectivity change. Our evaluation procedure is facilitated by using a structured and tool-supported approach, combining real world experiments with simulation and emulation. This method enables us to find performance-critical time regions in our traces. Our analysis shows that performance is largely determined by how accurately a protocol senses connectivity in these regions. Inaccurate sensing can seriously affect the performance of the protocol, even after the critical regions. We identify three significant problems with sensing that we call Self-interference, TCP backlashing and Link cache poisoning. We discuss their effect on the design of sensing mechanisms in routing protocols and suggest how the protocols can be made more robust.

  • 41.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wibling, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Comparing Simulation, Emulation, and Real-World Experimental Results in Mobile Ad hoc Networks2006In: 6th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'06), 2006Conference paper (Refereed)
    Abstract [en]

    We compare the major MANET protocols, AODV, DSR and OLSR, using a set of the same scenarios recreated in simulation, emulation and real world. The purpose of this is twofold:

    1. To explore the utility of simulation and emulation in direct relation to the real world in the area of mobile ad hoc networks. We explore potential discrepancies in the results that could either improve the confidence in previous research or to indicate the need for deeper exploration. To our knowledge, no previous work has done this in the consistent manner that we have. Our work may also function as a validation to previous findings in simulation and emulation.

    2. To compare, side-by-side, the performance of the major MANET routing protocols to better understand the trade-offs in the design choices of the different protocols and how they can complement each other to improve MANET routing. The MANET research area has reached a level of maturity, both in terms of protocol specifications and implementations, where we believe this type of comparison is necessary to further the development and standardization of MANET technology. In this paper we will concentrate on the first aspect of exploring potential discrepancies in the results. Significant differences have been identified in delay variation, packet loss, and interaction with transport layer protocols.

  • 42.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wibling, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Evaluating Wireless Multi-hop Networks Using a Combination of Simulation, Emulation, and Real World Experiments2007In: Proceedings of the 1st international workshop on System evaluation for mobile platforms (MobiEval'07) / [ed] Pering, Agarwal, Corner, New York: ACM Association for Computing Machinery , 2007, p. 29-34Conference paper (Refereed)
    Abstract [en]

    Mobile ad hoc networks suffer from complex interactions between protocols on different levels. To identify and explain anomalies found in real world experiments we propose to combine real world testing with simulation and emulation. By inspecting the differences in the results obtained using the three evaluation methods we can efficiently identify when anomalies occur and get a hint about where to further investigate. Our approach has proved to be valuable in an extensive comparison of the routing protocols AODV, DSR, and OLSR. The study resulted in two gigabytes of log data that required an efficient and structured method to isolate important time regions for further manual analysis. We discuss our approach and present some key findings.

  • 43.
    Nordström, Erik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Interaction between TCP and UDP flows in Wireless Multi-hop Ad hoc Networks2005In: Proceedings of the 5th Scandinavian Workshop on Wireless Ad-hoc Networks (Adhoc'05), 2005Conference paper (Refereed)
    Abstract [en]

    he interaction between TCP and UDP flows are examined experimentally in simple scenarios, involving between three and four nodes. Early results show that TCP’s congestion control is not tuned to wireless multi-hop settings, resulting in significant jitter and loss in UDP flows.

  • 44.
    Nordström, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bjurefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aldman, Daniel
    Search-Based Picture Sharing With Mobile Phones: Demo2009In: ACM MobiHoc, New Orleans, 2009Conference paper (Refereed)
  • 45. Nordström, Erik
    et al.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gunningberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Haggle: Opportunistic mobile content sharing using search2014In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 48, p. 121-132Article in journal (Refereed)
    Abstract [en]

    We present Haggle, a content-sharing system for mobile devices, allowing users to opportunistically share content without the support of infrastructure. Mobile devices share content and interests over direct WiFi or Bluetooth links, and may store-carry-forward content on behalf of others based on interests, bridging otherwise disconnected devices. Unlike traditional Internet-based content sharing systems, Haggle faces disconnections, unpredictable mobility, and time-limited contacts, which pose unique challenges to the system's design and implementation. While similar content-sharing systems typically value every content item the same, Haggle uses a ranked search to judiciously decide which content to exchange, and in which order. The search matches a device's locally stored content against the interests of other users that the device has collected, prioritizing relevant content when contacts are time limited and resources scarce. Thus, search enables dissemination of content in order of how strongly users desire it, offering delay and resource savings by exchanging the content that matters. An optional content delegation mechanism allows Haggle to altruistically disseminate a limited amount of items based on the interests of third-party nodes, increasing the benefit of the network as a whole, and protecting against networks that are partitioned along interests. Ranked searches, combined with delegation, allow Haggle to balance the short-term benefit of exchanging a content item between two nodes against the long-term benefit to the network as a whole. We evaluate Haggle through a real-world experiment with mobile phones, running a picture sharing application, complemented by trace-based emulations. Our results show that a content item whose interest group (the nodes that desire it) has strong interests is delivered with lower delay, and to a higher fraction of members, than an item with a similar sized group with weak interests. Compared to a relevance-agnostic system, Haggle can deliver the most relevant items in one third of the time and at a lower cost. 

  • 46.
    Rodhe, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A study of the message complexity for integrity preserving aggregation schemes used in wireless sensor networks2009Conference paper (Refereed)
  • 47.
    Rodhe, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    n-LDA: n-Layers Data Aggregation in Sensor Networks2008In: Proc. 28th International Conference on Distributed Computing Systems Workshops, Piscataway, NJ: IEEE , 2008, p. 400-405Conference paper (Refereed)
  • 48.
    Rodhe, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Secure Overlays: Making Static Key Distribution Schemes Work with Mobile Base Stations in WSNs2010In: Wired/Wireless Internet Communications / [ed] Evgeny Osipov, Andreas Kassler, Thomas Michael Bohnert, Xavier Masip-Bruin, Berlin: Springer-Verlag , 2010, p. 386-397Conference paper (Refereed)
  • 49.
    Rodhe, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Achtzehn, Andreas
    RWTH Aachen.
    n-LQA: n-Layers Query Authentication in Sensor Networks2007In: 3rd IEEE International Workshop on Wireless and Sensor Networks Security (IEEE WSNS 2007), 2007Conference paper (Refereed)
    Abstract [en]

    We present a protocol for query authentication in a sensor network where there is multi-hop communication and the queries are broadcasted by the base station into the network. Authenticating the queries is important so attackers cannot modify existing queries because this would lead to wrong

    readings; or insert new ones into the network because this would lead to waste of energy. We propose a layered query authentication protocol that ensures that, in the presence of less than n captured nodes, unauthorized queries are stopped after a small number of hops. When more than n nodes are captured, the unauthorized queries will only spread in one direction with a limited angle. Message authentication codes (MACs) are used to protect the authenticity and integrity of the query. n MACs are

    attached to the query message at the base station and the nodes replace MACs from this message in an interleaved manner.

  • 50.
    Rodhe, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rohner, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    On location privacy and quality of information in participatory sensing2012In: Proc. 8th ACM Symposium on QoS and Security for Wireless and Mobile Networks, New York: ACM Press, 2012, p. 55-62Conference paper (Refereed)
    Abstract [en]

    Participatory sensing applications typically bind sensor data to locations. Location privacy preserving mechanisms protecting the location of users introduce therefore an uncertainty in the collected data distributions. We consider two strategies to reconstruct a data distribution after k-anonymity has been applied to the users' location information. We investigate how different parameters for the location privacy preserving mechanism influence both the quality of information and the location privacy of the users. Our results show that the cloak area resulted from applying k-anonymity has a higher impact on both the quality of information and the location privacy than the number of users, k, that are cloaked together.

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