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  • 1.
    Asplund, Mikael
    et al.
    Trinity College Dublin.
    Manzoor, Atif
    Trinity College Dublin.
    Bouroche, Mélanie
    Trinity College Dublin.
    Clarke, Siobhan
    Trinity College Dublin.
    Cahill, Vinny
    Trinity College Dublin.
    A Formal Approach to Autonomous Vehicle Coordination2012In: FM 2012: Formal Methods: 18th International Symposium, Paris, France, August 27-31, 2012. Proceedings / [ed] Dimitra Giannakopoulou and Dominique Méry, Springer Berlin/Heidelberg, 2012, p. 52-67Chapter in book (Refereed)
    Abstract [en]

    Increasing demands on safety and energy efficiency will require higher levels of automation in transportation systems. This involves dealing with safety-critical distributed coordination. In this paper we demonstrate how a Satisfiability Modulo Theories (SMT) solver can be used to prove correctness of a vehicular coordination problem. We formalise a recent distributed coordination protocol and validate our approach using an intersection collision avoidance (ICA) case study. The system model captures continuous time and space, and an unbounded number of vehicles and messages. The safety of the case study is automatically verified using the Z3 theorem prover.

  • 2.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    A Partition-tolerant Manycast Algorithm for Disaster Area Networks2009In: 28TH IEEE INTERNATIONAL SYMPOSIUM ON RELIABLE DISTRIBUTED SYSTEMS, PROCEEDINGS, IEEE Computer Society, 2009, p. 156-165Conference paper (Refereed)
    Abstract [en]

    Information dissemination in disaster scenarios requires timely and energy-efficient communication in intermittently connected networks. When the existing infrastructure is damaged or overloaded, we suggest the use of a manycast algorithm that runs over a wireless mobile ad hoc network, and overcomes partitions using a store-and-forward mechanism. This paper presents a random walk gossip protocol that uses an efficient data structure to keep track of already informed nodes with minimal signalling. Avoiding unnecessary transmissions also makes it less prone to overloads. Experimental evaluation shows higher delivery ratio, lower latency, and lower overhead compared to a recently published algorithm.

  • 3.
    Strömbäck, Filip
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Mannila, Linda
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Kamkar, Mariam
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    A Student's View of Concurrency: A Study of Common Mistakes in Introductory Courses on Concurrency2019In: Proceedings of the 2019 ACM Conference on International Computing Education Research, New York, NY, USA: Association for Computing Machinery (ACM), 2019, p. 229-237Conference paper (Refereed)
    Abstract [en]

    This paper investigates common misconceptions held by students regarding concurrency in order to better understand how concurrency education can be improved in the future. As a part of the exam in two courses on concurrency and operating systems, students were asked to identify and eliminate any concurrency issues in a piece of code as a part of their final exam. Different types of mistakes were identified and the 216 answers were sorted into categories accordingly. The results presented in this paper show that while most students were able to identify the cause of an issue given its symptoms, only approximately half manage to successfully eliminate the concurrency issues. Many of the incorrect solutions fail to associate shared data with a synchronization primitive, e.g. using one lock to protect multiple instances of a data structure, or multiple locks to protect the same instance in different situations. This suggests that students may not only have trouble dealing with concepts related to concurrency, but also more fundamental concepts related to the underlying computational model. Finally, this paper proposes possible explanations for the students' mistakes in terms of improper mental models, and suggests types of problems that highlight the issues with these mental models to improve students' understanding of the subject.

  • 4.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Analysing Delay-tolerant Networks with Correlated Mobility2012In: Ad-hoc, Mobile, and Wireless Networks: 11th International Conference, ADHOC-NOW 2012, Belgrade, Serbia, July 9-11, 2012. Proceedings / [ed] Xiang-Yang Li, Symeon Papavassiliou, Stefan Ruehrup, Springer , 2012, p. 83-97Conference paper (Refereed)
    Abstract [en]

    This book constitutes the refereed proceedings of the 11th International Conference on Ad-hoc, Mobile, and Wireless Networks, ADHOC-NOW 2012 held in Belgrade, Serbia, July 9-11, 2012. The 36 revised full papers presented were carefully reviewed and selected from 76 submissions. The accepted papers cover a wide spectrum of traditional networking topics ranging from routing to the application layer, to localization in various networking environments such as wireless sensor and ad-hoc networks, and give insights in a variety of application areas.

  • 5.
    Cucurull, Jordi
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Anomaly detection and mitigation for disaster area networks2010In: Recent Advances in Intrusion Detection: 13th International Symposium, RAID 2010, Ottawa, Ontario, Canada, September 15-17, 2010. Proceedings / [ed] Somesh Jha, Robin Sommer and Christian Kreibich, Springer Berlin/Heidelberg, 2010, p. 339-359Chapter in book (Refereed)
    Abstract [en]

    One of the most challenging applications of wireless networking are in disaster area networks where lack of infrastructure, limited energy resources, need for common operational picture and thereby reliable dissemination are prevalent.In this paper we address anomaly detection in intermittently connected mobile ad hoc networks in which there is little or no knowledge about the actors on the scene, and opportunistic contacts together with a store-and-forward mechanism are used to overcome temporary partitions. The approach uses a statistical method for detecting anomalies when running a manycast protocol for dissemination of important messages to k receivers. Simulation of the random walk gossip (RWG) protocol combined with detection and mitigation mechanisms is used to illustrate that resilience can be built into a network in a fully distributed and attack-agnostic manner, at a modest cost in terms of drop in delivery ratio and additional transmissions. The approach is evaluated with attacks by adversaries that behave in a similar manner to fair nodes when invoking protocol actions.

  • 6.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Attitudes and Perceptions of IoT Security in Critical Societal Services2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 2130-2138Article in journal (Refereed)
    Abstract [en]

    A quiet revolution that impacts several sectors, ranging over transport, home automation, energy, industrial control, and health services is undergoing with addition of new networked devices leading to enhanced services. In this paper, we aim to identify information security requirements that are common over several (vertical) sectors, and in particular, ones that impact critical societal services, namely, the energy, water, and health management systems. We present the results of an interview-based study where actors in these sectors were asked about their perceptions and attitudes on the security of Internet of Things (IoT). We set these perceptions and attitudes in context through a literature review of IoT security, and relate to current challenges in this area. This paper demonstrates that despite an overall optimistic view on IoT in critical societal services, there is a lack of consensus on risks related to IoT security.

  • 7.
    Lundberg, Jonas
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Communication Problems in Crisis Response2011In: Proceedings of the 8th International ISCRAM Conference: Lisbon, Portugal, May 2011 , Information Systems for Crisis Response and Management, ISCRAM , 2011Conference paper (Refereed)
    Abstract [en]

    This paper describes five problem areas of communication that occur during crisis response. These areas arecommunication infrastructure, situation awareness, individual and organizational common ground, form andcontent of messages, and communication paths through organizations. Five focus groups with Swedish fieldpersonnel from national and international crises were performed. The main contribution of this article is ahypothesis, based on the outcomes of the focus groups, about the relation between communication problems andhow they interact with crisis response work.

  • 8.
    Hultman, Tim
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Boudjadar, Abdeldjalil
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Connectivity-optimal Shortest Paths Using Crowdsourced Data2016In: 2016 IEEE International Conference on Pervasive Computing and Communication Workshops (PerCom Workshops), IEEE Computer Society, 2016, p. 1-6Conference paper (Refereed)
    Abstract [en]

    With the increasing dependency of ubiquitous connectivity for applications ranging from multimedia entertainment to intelligent transportation systems, having good signal coverage becomes vital. Therefore, route planners and navigation systems should take into account not only the physical distance, but also the characteristics and availability of the cellular network on the potential routes. In this paper we present a route planning tool that finds the connectivity-aware shortest paths based on crowdsourced data from OpenStreetMap and OpenSignal. The tool calculates optimal paths and allows physical distance tobe traded against signal quality. The evaluation shows that a 15% increase of the physical path length can achieve an 8.7dBm improvement of worst-case signal strength.

  • 9.
    Bianzino, Aruna Prem
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Cooperative proxies: Optimally trading energy and quality of service in mobile devices2014In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 75, no Part A, p. 297-312Article in journal (Refereed)
    Abstract [en]

    This work studies the energy and quality of service (QoS) trade-off in the context of mobile devices with two communication interfaces (a high energy and a low energy interface). We propose an optimisation scheme during underload scenarios where proxy groups are dynamically formed exploiting both interfaces. The scheme integrates a reward mechanism that compensates a proxy while carrying other group members’ traffic, and deals with churn (joining and leaving of nodes) in a cell area. For traffic flows that approximate knowledge about current services we show that the scheme can achieve energy savings of 60% for all mobile nodes as whole. We also demonstrate the impact on disruption-sensitive flows as a function of the traffic mix, and that the use of rewards for selection of proxies is a fair mechanism in the long term.

  • 10.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Disconnected Discoveries: Availability Studies in Partitioned Networks2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis is concerned with exploring methods for making computing systems more resilient to problems in the network communication, both in the setting of existing infrastructure but also in the case where no infrastructure is available. Specifically, we target a situation called network partitions which means that a computer or device network is split in two or more parts that cannot communicate with each other.

    The first of the two tracks in the thesis is concerned with upholding system availability during a network partition even when there are integrity constraints on data. This means that the system will optimistically accept requests since it is impossible to coordinate nodes that have no means of communicating during finite intervals; thus requiring a reconciliation process to take place once the network is healed.

    We provide several different algorithms for reconciling divergent states of the nodes, one of which is able to allow the system to continue accepting operations during the reconciliation phase as opposed to having to stop all invocations.  The algorithms are evaluated analytically, proving correctness and the conditions for termination.  The performance of the algorithms has been analysed using simulations and as a middleware plugin in an emulated setting.

    The second track considers more extreme conditions where the network is partitioned by its nature. The nodes move around in an area and opportunistically exchange messages with nodes that they meet. This as a model of the situation in a disaster area where the telecommunication networks are disabled. This scenario poses a number of challenges where protocols need to be both partition-tolerant and energy-efficient to handle node mobility, while still providing good delivery and latency properties.

    We analyse worst-case latency for message dissemination in such intermittently connected networks. Since the analysis is highly dependent on the mobility of the nodes, we provide a model for characterising connectivity of dynamic networks. This model captures in an abstract way how fast a protocol can spread a message in such a setting. We show how this model can be derived analytically as well as from actual trace files.

    Finally, we introduce a manycast protocol suited for disaster area networks. This protocol has been evaluated using simulations which shows that it provides very good performance under the circumstances, and it has been implemented as a proof-of-concept on real hardware.

  • 11.
    Boeira, Felipe
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering. Univ Fed Rio Grande do Sul, Brazil; Halmstad Univ, Sweden.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    de Freitas, Edison P.
    Univ Fed Rio Grande do Sul, Brazil.
    Vinel, Alexey
    Halmstad Univ, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Effects of Colluding Sybil Nodes in Message Falsification Attacks for Vehicular Platooning2017In: 2017 IEEE VEHICULAR NETWORKING CONFERENCE (VNC), IEEE , 2017, p. 53-60Conference paper (Refereed)
    Abstract [en]

    This paper studies the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Platooning employs Inter-Vehicular Communication (IVC) to control a group of vehicles. It uses broadcast information such as acceleration, position, and velocity to operate a longitudinal control law. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of network communication to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. To carry out this study, we evaluate five scenarios to quantify the potential impact of such attacks, identifying how platoons behave under varying Sybil attack conditions and what are the associated safety risks. This research also presents the use of location hijacking attack. In this attack, innocent vehicles that are not part of a platoon are used as a way to create trust bond between the false identities and the physical vehicles. We demonstrate that the ability to create false identities increases the effectiveness of message falsification attacks by making them easier to deploy and harder to detect in time.

  • 12.
    Asplund, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Nadjm-Tehrani, Simin
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Sigholm, Johan
    Swedish National Defence College.
    Emerging Information Infrastructures: Cooperation in Disasters2009In: Critical Information Infrastructure Security: Third International Workshop, CRITIS 2008, Rome, Italy, October13-15, 2008. Revised Papers / [ed] Roberto Setola, Stefan Geretshuber, Springer Berlin/Heidelberg, 2009, p. 258-270Conference paper (Refereed)
    Abstract [en]

      In this paper we describe how to include high level semantic information, such as aesthetics and emotions; into Content Based Image Retrieval. We present a, color-based emotion-related image descriptor that can be used for describing the emotional content of images. The color emotion metric used is derived from psychophysical experiments rind based oil three variables: activity, weight and teat. It was originally designed for single-colors, bill, recent research has shown that the salve emotion estimates call be applied in the retrieval of multi-colored images. Here we describe a new approach, based oil the assumption that perceived color emotions in images are mainly affected by homogenous regions, defined by the emotion metric; and transitions between regions. RGB coordinates are converted to emotion coordinates, mid for each emotion channel, statistical measurements of gradient magnitudes within a. stack of low-pass filtered images are used for finding interest; points corresponding to homogeneous regions and transitions between regions. Emotion characteristics are derived for patches surrounding cacti interest, point, and saved in a, bag-of-emotions; that for instance, can be used for retrieving images based oil emotional content.

  • 13.
    Udd, Robert
    et al.
    Sectra AB, Linköping, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Kazemtabrizi, Mehrdad
    The Royal Institute of Technology, Stockholm, Sweden.
    Ekstedt, Mathias
    The Royal Institute of Technology, Stockholm, Sweden.
    Exploiting Bro for Intrusion Detection in a SCADA System2016In: Proceedings of the 2nd ACM International Workshop on Cyber-Physical System Security, ACM Digital Library, 2016, p. 44-51Conference paper (Refereed)
    Abstract [en]

    Supervisory control and data acquisition (SCADA) systemsthat run our critical infrastructure are increasingly run withInternet-based protocols and devices for remote monitoring.The embedded nature of the components involved, and thelegacy aspects makes adding new security mechanisms in anefficient manner far from trivial. In this paper we studyan anomaly detection based approach that enables detect-ing zero-day malicious threats and benign malconfigurationsand mishaps. The approach builds on an existing platform(Bro) that lends itself to modular addition of new proto-col parsers and event handling mechanisms. As an examplewe have shown an application of the technique to the IEC-60870-5-104 protocol and tested the anomaly detector withmixed results. The detection accuracy and false positiverate, as well as real-time response was adequate for 3 ofour 4 created attacks. We also discovered some additionalwork that needs to be done to an existing protocol parser toextend its reach.

  • 14.
    Vergara, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fairness and Incentive Considerations in Energy Apportionment Policies2016In: ACM Transactions on Modeling and Performance Evaluation of Computing Systems, ISSN 2376-3639, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    The energy consumption of a system is determined by the system component usage patterns and interactions between the coexisting entities and resources. Energy accounting plays an essential role in revealing the contribution of each entity to the total consumption and for energy management. Unfortunately, energy accounting inherits the apportionment problem of accounting in general, which does not have a general single best solution. In this article, we leverage cooperative game theory, which is commonly used in cost allocation problems to study the energy apportionment problem, that is, the problem of prescribing the actual energy consumption of a system to the consuming entities (e.g., applications, processes, or users of the system).

    We identify five relevant fairness properties for energy apportionment and present a detailed categorisation and analysis of eight previously proposed energy apportionment policies from different fields in computer and communication systems. In addition, we propose two novel energy apportionment policies based on cooperative game theory that provide strong fairness notion and a rich incentive structure. Our comparative analysis in terms of the identified five fairness properties as well as information requirement and computational complexity shows that there is a tradeoff between fairness and the other evaluation criteria. We provide guidelines to select an energy apportionment policy depending on the purpose of the apportionment and the characteristics of the system.

  • 15.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Formalising Reconciliation in Partitionable Networks with Distributed Services2006In: Rigorous Development of Complex Fault-Tolerant Systems / [ed] Michael Butler, Cliff Jones, Alexander Romanovsky, Elena Troubitsyna, Heidelberg: Springer Verlag , 2006, p. 37-58Chapter in book (Refereed)
    Abstract [en]

    This book brings together 19 papers focusing on the application of rigorous design techniques to the development of fault-tolerant, software-based systems. It is an outcome of the REFT 2005 Workshop on Rigorous Engineering of Fault-Tolerant Systems held in conjunction with the Formal Methods 2005 conference at Newcastle upon Tyne, UK, in July 2005.

  • 16.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Lövhall, Jakob
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    In-store payments using Bitcoin2018In: 9th IFIP International Conference on New Technologies, Mobility and Security (NTMS), IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    The possibility of in-store payments would further increase the potential usefulness of cryptocurrencies. However, this would require much faster transaction verification than current solutions provide (one hour for Bitcoin) since customers are likely not prepared to wait a very long time for their purchase to be accepted by a store. We propose a solution for enabling in-store payments with waiting times in the order of a few seconds, which is still compatible with the current Bitcoin protocol. The idea is based on a payment card in combination with a protocol for ensuring that losing a card does not mean losing the money on it. We analyse the required transaction verification delay and also the potentially added risks that the solution brings compared to current systems.

  • 17.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Beyer, Stefan
    Instituto Tecnolgico Informtica Universidad Politcnica de Valencia, Spain.
    Galdamez, Pablo
    Instituto Tecnolgico Informtica Universidad Politcnica de Valencia, Spain.
    Measuring Availability in Optimistic Partition-Tolerant Systems with Data Constraints2007In: Dependable Systems and Networks, DSN 2007, IEEE Computer Society, 2007, p. 656-665Conference paper (Refereed)
    Abstract [en]

    Replicated systems that run over partitionable environments, can exhibit increased availability if isolated partitions are allowed to optimistically continue their execution independently. This availability gain is traded against consistency, since several replicas of the same objects could be updated separately. Once partitioning terminates, divergences in the replicated state needs to be reconciled. One way to reconcile the state consists of letting the application manually solve inconsistencies. However, there are several situations where automatic reconciliation of the replicated state is meaningful. We have implemented replication and automatic reconciliation protocols that can be used as building blocks in a partition-tolerant middleware. The novelty of the protocols is the continuous service of the application even during the reconciliation process. A prototype system is experimentally evaluated to illustrate the increased availability despite network partitions.

  • 18.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Zagar, Klemen
    Cosylab.
    Middleware extensions that trade consistency for availability2009In: CONCURRENCY AND COMPUTATION-PRACTICE and EXPERIENCE, ISSN 1532-0626, Vol. 21, no 9, p. 1181-1203Article in journal (Refereed)
    Abstract [en]

    Replicated distributed object systems are deployed to provide timely and reliable services to actors at distributed locations. This paper treats applications in which data updates are dependent on satisfaction of integrity constraints over multiple objects. Network partitions, caused by occasional link failures, overload or attacks create problems in keeping both consistency and availability in such networks. We propose a means of achieving higher availability by providing partition-awareness in middleware. The general approach has been illustrated by implementing a number of CORBA extensions that trade consistency for availability during network partitions. This paper contains a thorough experimental evaluation that presents the gains and costs of our approach. The experiments clearly illustrate the benefit of our protocols in terms of significantly higher availability and the number of performed operations.

  • 19.
    Boeira, Felipe
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    Mitigating Position Falsification Attacks in Vehicular Platooning2018In: 2018 IEEE VEHICULAR NETWORKING CONFERENCE (VNC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    As connected vehicles are envisioned to provide novel intelligent transportation systems, cyberattacks and security schemes are becoming an increasing concern. Several studies have shown that algorithms that make use of location information from other vehicles, such as vehicular platoon controllers, are vulnerable to message falsification attacks. Moreover, the ability for an attacking vehicle to appear as several vehicles through a so-called Sybil attack can significantly increase the severity of the attack. In this paper, we investigate how these attacks can be detected using Vouch location proof scheme (by identifying false location messages) and propose several reaction strategies to mitigate them. We also show through simulation that it is possible to prevent collisions by reacting appropriately to the false beacons in time while not reacting to false positives coming from the detector.

  • 20.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Model-based Membership Verification in Vehicular Platoons2015In: Proceedings: 2015 45th Annual IEEE/IFIP International Conference on Dependable Systems and Networks Workshops , IEEE Computer Society, 2015, p. 125-132Conference paper (Refereed)
    Abstract [en]

    Cooperative vehicular systems have the potentialto significantly increase traffic efficiency and safety. However,they also raise the question of to what extent information thatis received from other vehicles can be trusted. In this paperwe present a novel approach for increasing the trustworthinessof cooperative driving through a model-based approach forverifying membership views in vehicular platoons. We define aformal model for platoon membership, cooperative awarenessclaims, and membership verification mechanisms. With the helpof a satisfiability solver, we are able to quantitatively analysethe impact of different system parameters on the verifiability ofreceived information. Our results demonstrate the importance ofcross validating received messages, as well as the surprising diffi-culty in establishing correct membership views despite powerfulverification mechanisms.

  • 21.
    Boeira, Felipe
    et al.
    Univ Fed Rio Grande do Sul, Brazil.
    Barcellos, Marinho P.
    Univ Fed Rio Grande do Sul, Brazil.
    de Freitas, Edison P.
    Univ Fed Rio Grande do Sul, Brazil.
    Vinel, Alexey
    Halmstad Univ, Sweden.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    On the Impact of Sybil Attacks in Cooperative Driving Scenarios2017In: 2017 IFIP NETWORKING CONFERENCE (IFIP NETWORKING) AND WORKSHOPS, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Platooning employs a set of technologies to manage how a group of vehicles operates, including radar, GPS and Inter-Vehicular Communication (IVC). It uses broadcasted information such as acceleration, position and velocity to operate vehicle members of the platoon. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of IVC to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. In this paper we study the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Simulation results show that this attack may impact the longitudinal control and compromise the entire platoon control.

  • 22.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Poster: Securing Vehicular Platoon Membership2014In: Proceedings of IEEE Vehicular Networking Conference (VNC), IEEE Computer Society, 2014, p. 119-120Conference paper (Refereed)
    Abstract [en]

    Vehicular platoons have the potential to bring considerable fuel-savings and increase traffic efficiency. A key component for the next generation platoon systems is a secure membership component which can accommodate membership changes in a dynamic and potentially hostile environment. In this poster paper we analyse the conditions for creating a secure membership protocol which is resilient to attacks and faults in the communication protocols.

  • 23.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Post-Partition Reconciliation Protocols for Maintaining Consistency2006Conference paper (Refereed)
    Abstract [en]

    This paper addresses design exploration for protocols thatare employed in systems with availability-consistency tradeoffs. Distributed data is modelled as states of objects replicated across a network, and whose updates require satisfaction of integrity constraints over multiple objects. Upondetection of a partition, such a network will continue toprovide delivery of services in parallel partitions; but onlyfor updates with non-critical integrity constraints. Once thedegraded mode ends, the parallel network partitions are reconciled to arrive at one partition.Using a formal treatment of the reconciliation process,three algorithms are proposed and studied in terms of theirinfluence on service outage duration. The longer the reconciliation time, the lower is system availability; since theinterval in which no services are provided is longer. However, the reconciliation time in turn is affected by the time toconstruct the post-partition system state. The shorter theconstruction time the higher is the number of updates thattook place in the degraded mode but that will not be takenup in the reconciled partition. This will lead to a longerinterval for rejecting/redoing these operations and therebyincrease reconciliation time.

  • 24.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Post-Partition Reconciliation Protocols for Maintaning Consistency2006In: SAC '06 Proceedings of the 2006 ACM symposium on Applied computing, New York, NY, USA: ACM Press, 2006, p. 710-717Conference paper (Refereed)
    Abstract [en]

    This paper addresses design exploration for protocols that are employed in systems with availability-consistency trade-offs. Distributed data is modelled as states of objects replicated across a network, and whose updates require satisfaction of integrity constraints over multiple objects. Upon detection of a partition, such a network will continue to provide delivery of services in parallel partitions; but only for updates with non-critical integrity constraints. Once the degraded mode ends, the parallel network partitions are reconciled to arrive at one partition. Using a formal treatment of the reconciliation process, three algorithms are proposed and studied in terms of their influence on service outage duration. The longer the reconciliation time, the lower is system availability; since the interval in which no services are provided is longer. However, the reconciliation time in turn is affected by the time to construct the post-partition system state. The shorter the construction time the higher is the number of updates that took place in the degraded mode but that will not be taken up in the reconciled partition. This will lead to a longer interval for rejecting/redoing these operations and thereby increase reconciliation time.

  • 25.
    Asplund, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Nadjm-Tehrani, Simin
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    Random walk gossip-based manycast with partition detection2008In: Supplemental Proceedings of the International Conference on Dependable Systems and Networks, DSN, 2008, IEEE Computer Society , 2008, p. G40-G41Conference paper (Other academic)
    Abstract [en]

       

  • 26.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Rapid selection and dissemination of urgent messages over delay-tolerant networks (DTNs)2015In: Advances in Delay-Tolerant Networks (DTNs): Architecture and Enhanced Performance / [ed] J. Rodrigues, Elsevier, 2015, p. 187-203Chapter in book (Refereed)
    Abstract [en]

    Today many new applications are emerging that take advantage of wireless communication in handheld and embedded devices. Some of these emerging applications, such as information sharing in vehicular systems, have strong requirements for timely message dissemination, even if the network is not always 100% connected. In this chapter we discuss message differentiation mechanisms that can be used in intermittently connected networks to improve delivery and latency properties when messages have a limited time to live in the network. We present a simulation-based study on a large-scale vehicular scenario comparing different prioritisation mechanisms for a partition-tolerant manycast protocol. We show that negative effects of overloads can be significantly reduced by using information within the message about how far it has spread and how much time is remaining.

  • 27.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Zurutuza, Urko
    Mondragon University, Spain.
    Resource Footprint of a Manycast Protocol Implementation on Multiple Mobile Platforms2011Conference paper (Refereed)
    Abstract [en]

    Wireless communication is becoming the dominant form of communication and ad hoc wireless connections are posed to play a role in disaster area networks. However, research efforts on wireless ad hoc communication protocols do not pay enough attention to measurable and reproducible indications of the mobile footprint including power consumption. Protocols and applications are initially designed and studied in a simulation environment and are hard to test in in-field experiments. In this work we report a multi-platform implementation of Random-Walk Gossip, a manycast protocol designed for message dissemination in disaster areas. Our work is focused in studying the resource footprint and its impact on performance on commercially available devices. We show both how different aspects of the protocol contributes to the footprint and how this in turn affects the performance. The methodologies used here can be applied to other protocols and applications, aiding in future optimisations.

  • 28.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Restoring Consistency after Network Partitions2007Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The software industry is facing a great challenge. While systems get more complex and distributed across the world, users are becoming more dependent on their availability. As systems increase in size and complexity so does the risk that some part will fail. Unfortunately, it has proven hard to tackle faults in distributed systems without a rigorous approach. Therefore, it is crucial that the scientific community can provide answers to how distributed computer systems can continue functioning despite faults.

    Our contribution in this thesis is regarding a special class of faults which occurs whennetwork links fail in such a way that parts of the network become isolated, such faults are termed network partitions. We consider the problem of how systems that have integrity constraints on data can continue operating in presence of a network partition. Such a system must act optimistically while the network is split and then perform a some kind of reconciliation to restore consistency afterwards.

    We have formally described four reconciliation algorithms and proven them correct. The novelty of these algorithms lies in the fact that they can restore consistency after network partitions in a system with integrity constraints and that one of the protocols allows the system to provide service during the reconciliation. We have implemented and evaluated the algorithms using simulation and as part of a partition-tolerant CORBA middleware. The results indicate that it pays off to act optimistically and that it is worthwhile to provide service during reconciliation.

  • 29.
    Vergara Alonso, Ekhiotz Jon
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Sharing the Cost of Lunch: Energy Apportionment Policies2015In: Proceedings of the 11th ACM Symposium on QoS and Security for Wireless and Mobile Networks, ACM Digital Library, 2015, p. 91-97Conference paper (Refereed)
    Abstract [en]

    Energy consumption has become a hot topic in computer and communication technologies pinpointing the need to carefully analyse system efficiency. The energy consumption of a system is determined by the usage patterns of system components and complex interactions between the coexisting entities and resources. Providing transparency of a system’s consumption by breaking down the total consumption is vital to evaluate and provide energy-efficient design and operation.

    In this paper we survey the apportionment problem in different fields such as computer systems, wireless sensor networks, mobile devices and energy-efficient buildings. The challenge lies in how to attribute a share of the total energy consumption to the responsible entities (e.g., applications, processes or users of the system). Our analysis identifies that energy apportionment is a common problem in different fields and reviews five previously applied energy apportionment policies. Also, the work identifies relevant further research.

  • 30.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Thomasson, Anton
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Vergara Alonso, Ekhiotz Jon
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Software-related Energy Footprint of a Wireless Broadband Module2011In: The 9th ACM International Symposium on Mobility Management and Wireless Access (MobiWac), ACM , 2011Conference paper (Refereed)
    Abstract [en]

    Energy economy in mobile devices is becoming an increasinglyimportant factor as the devices become more advancedand rich in features. A large part of the energy footprint of amobile device comes from the wireless communication module,and even more so as the amount of trac increases.In this paper we study the energy footprint of a mobilebroadband hardware module, and how it is aected by software,by performing systematic power consumption measurements.We show that there are several cases where thesoftware does not properly take into account the eect thatdata communication has on the power consumption. Thisopens up for potential energy savings by creating better applicationsthat are aware of the energy characteristics of thecommunication layer.

  • 31.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Lövhall, Jakob
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Villani, Emilia
    Auronatics Institute of Technology, Brazil.
    Specification, Implementation and Verification of Dynamic Group Membership for Vehicle Coordination2017In: Dependable Computing (PRDC), 2017 IEEE 22nd Pacific Rim International Symposium on, IEEE, 2017, p. 321-328Conference paper (Refereed)
    Abstract [en]

    New advanced traffic management solutions with fully or semi-autonomous vehicles that communicate over a wireless interface to coordinate their driving decisions create new challenges in distributed computing. In this paper we address the problem of dynamic group membership in three stages. First, we propose three criteria to specify correctness and performance of the group views created by such algorithms in terms of soundness, completeness and freshness. Second, we develop a group membership protocol tailored for vehicular coordination. Finally, we show through simulation and model-based verification that the protocol does indeed meet the criteria and provide at least 95% perfect group membership views under as adverse conditions as 70% packet loss or very high churn rate.

  • 32.
    Cucurull, Jordi
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, Software and Systems.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Surviving Attacks in Challenged Networks2012In: IEEE Transactions on Dependable and Secure Computing, ISSN 1545-5971, E-ISSN 1941-0018, Vol. 9, no 6, p. 917-929Article in journal (Refereed)
    Abstract [en]

    In the event of a disaster, telecommunication infrastructures can be severely damaged or overloaded. Hastily formed networks can provide communication services in an ad hoc manner. These networks are challenging due to the chaotic context where intermittent connection is the norm and the identity and number of participants cannot be assumed. In such environments malicious actors may try to disrupt the communications to create more chaos for their own benefit. This paper proposes a general security framework for monitoring and reacting to disruptive attacks. It includes a collection of functions to detect anomalies, diagnose them, and perform mitigation. The measures are deployed in each node in a fully distributed fashion, but their collective impact is a significant resilience to attacks, so the actors can disseminate information under adverse conditions. The approach is evaluated in the context of a simulated disaster area network with a many-cast dissemination protocol, Random Walk Gossip, with a store-and-forward mechanism. A challenging threat model where adversaries may 1) try to drain the resources both at node level (battery life) and network level (bandwidth), or 2) reduce message dissemination in their vicinity, without spending much of their own energy, is adopted. The results demonstrate that the approach diminishes the impact of the attacks considerably.

  • 33.
    Lin, Chih-Yuan
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Timing-Based Anomaly Detection in SCADA Networks2018In: Critical Information Infrastructures Security, Springer, 2018, p. 48-59Conference paper (Refereed)
    Abstract [en]

    Supervisory Control and Data Acquisition (SCADA) systems that operate our critical infrastructures are subject to increased cyber attacks. Due to the use of request-response communication in polling, SCADA traffic exhibits stable and predictable communication patterns. This paper provides a timing-based anomaly detection system that uses the statistical attributes of the communication patterns. This system is validated with three datasets, one generated from real devices and two from emulated networks, and is shown to have a False Positive Rate (FPR) under 1.4%. The tests are performed in the context of three different attack scenarios, which involve valid messages so they cannot be detected by whitelisting mechanisms. The detection accuracy and timing performance are adequate for all the attack scenarios in request-response communications. With other interaction patterns (i.e. spontaneous communications), we found instead that 2 out of 3 attacks are detected.

  • 34.
    Viel, Brieuc
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Asplund, Mikael
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Why is fingerprint-based indoor localization still so hard?2014In: IEEE International Conference on Pervasive Computing and Communications Workshops (PERCOM Workshops), IEEE Computer Society, 2014, p. 443-448Conference paper (Refereed)
    Abstract [en]

    Wireless indoor localization systems and especially signal strength fingerprinting techniques have been the subject of significant research efforts in the last decades. However, most of the proposed solutions require a costly site-survey to build the radio map which can be used to match radio signatures with specific locations. We investigate a novel indoor localization system that addresses the data collection problem by progressively and semi-autonomously creating a radio-map with limited interaction cost. Moreover, we investigate how spatiotemporal and hardware properties-based variations can affect the RSSI values collected and significantly influence the resulting localization. We show the impact of these fluctuations on our system and discuss possible mitigations.

  • 35.
    Asplund, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory.
    de Lanerolle, Trishan
    Trinity College, Hartford, CT, USA.
    Fei, Christopher
    Trinity College, Hartford, CT, USA.
    Gautam, Prasanna
    Trinity College, Hartford, CT, USA.
    Morelli, Ralph
    Trinity College, Hartford, CT, USA.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, RTSLAB - Real-Time Systems Laboratory. Linköping University, The Institute of Technology.
    Nykvist, Gustav
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Wireless Ad Hoc Dissemination for Search and Rescue2010In: Proceedings of the 7th International ISCRAM Conference / [ed] Simon French, Brian Tomaszewski, Christopher Zobel, ISCRAM , 2010Conference paper (Refereed)
    Abstract [en]

    In search and rescue scenarios local information on victims and other finds needs to be disseminated rapidly toother rescue workers and team leaders. However, post disaster scenarios may imply the collapse of informationinfrastructure including cellular communication and Internet connectivity. Even if we consider wireless ad hoccommunication as a means of information dissemination we should count on frequent loss of connectivity in thenetwork due to unpredictable mobility and sparse network topologies. In this paper we present the realization ofan existing manycast protocol (random walk gossip) on commodity handheld devices running the Androidplatform. This communication mode is used to demonstrate the potential for distributed informationdissemination on victims and finds. The application layer is an adaptation of an existing surveying informationtool (POSIT) which is now fully decentralized and relies on text communication to achieve energy efficiency.

  • 36.
    Asplund, Mikael
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Nadjm-Tehrani, Simin
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Worst-case latency of broadcast in intermittently connected networks2012In: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 11, no 2-3, p. 125-138Article in journal (Refereed)
    Abstract [en]

    Worst-case latency is an important characteristic of information dissemination protocols. However, in sparse mobile ad hoc networks where end-to-end connectivity cannot be achieved and store-carry-forward algorithms are needed, such worst-case analyses have not been possible to perform on real mobility traces due to lack of suitable models. We propose a new metric called delay expansion that reflects connectivity and reachability properties of intermittently connected networks. Using the delay expansion, we show how bounds on worst-case latency can be derived for a general class of broadcast protocols and a wide range of real mobility patterns. The paper includes theoretical results that show how worst-case latency can be related with delay expansion for a given mobility scenario, as well as simulations to validate the theoretical model.

1 - 36 of 36
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