References of "Engel, Thomas 50001752"
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See detailDevice-Free Indoor Localization Based on Ambient FM Radio Signals
Popleteev, Andrei UL; Engel, Thomas UL

in International Journal of Ambient Computing and Intelligence (2014), 6(January-March), 35-44

This paper presents the concept of device-free indoor localization using only a passive receiver and ambient FM radio signals. Experimental results based on empirical measurements demonstrate the ... [more ▼]

This paper presents the concept of device-free indoor localization using only a passive receiver and ambient FM radio signals. Experimental results based on empirical measurements demonstrate the feasibility of the proposed approach. We also evaluate fine-grained localization performance of the system, its temporal stability, and highlight the role of frequency diversity for passive localization. [less ▲]

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See detailTowards Domain Completeness for Model Transformations Based on Triple Graph Grammars
Nachtigall, Nico UL; Hermann, Frank UL; Braatz, Benjamin UL et al

in Amrani, Moussa; Syriani, Eugene; Wimmer, Manuel (Eds.) Proceedings of the Third International Workshop on Verification of Model Transformations - co-located with Software Technologies: Applications and Foundations (STAF 2014) (2014)

The analysis of model transformations is a challenging research area within model driven engineering. Triple graph grammars (TGGs) have been applied in various transformation scenarios and their formal ... [more ▼]

The analysis of model transformations is a challenging research area within model driven engineering. Triple graph grammars (TGGs) have been applied in various transformation scenarios and their formal foundation has been a vital ground for general results concerning notions of correctness and completeness. This paper addresses existing gaps between practical scenarios and the formal results of TGGs concerning the notion of completeness. Since the source domain language of a model transformation is usually specified independently from the TGG, we use the notion of domain completeness, which requires that the model transformation has to provide a corresponding target model for each model of the source domain language. As main result, we provide a general method for showing that the source domain language is included in the language that is generated by the source rules of the TGG. This provides the first of two components for verifying domain completeness. The running example is the well studied object-relational mapping. [less ▲]

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See detailImplications and Detection of DoS Attacks in OpenFlow-based Networks
Hommes, Stefan UL; State, Radu UL; Engel, Thomas UL

in 2014 IEEE Global Communications Conference (2014)

In this paper, we address the potential of centralised network monitoring based on Software-Defined Networking with OpenFlow. Due to the vulnerability of the flow table, which can store only a limited ... [more ▼]

In this paper, we address the potential of centralised network monitoring based on Software-Defined Networking with OpenFlow. Due to the vulnerability of the flow table, which can store only a limited number of entries, we discuss and show the implications for a DoS attack on a testbed consisting of OpenFlow enabled network devices. Such an attack can be detected by analysing variations in the logical topology, using techniques from information theory that can run as a network service on the network controller. [less ▲]

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See detailA Study of Urban IEEE 802.11 Hotspot Networks: Towards a Community Access Network
Castignani, German UL; Monetti, Juan; Montavont, Nicolas et al

in A Study of Urban IEEE 802.11 Hotspot Networks: Towards a Community Access Network (2013, November 13)

With the increasing demand for faster data connectivity, different wireless technologies have been deployed in the last decade, creating a heterogeneous wireless environment. Such wireless diversity is ... [more ▼]

With the increasing demand for faster data connectivity, different wireless technologies have been deployed in the last decade, creating a heterogeneous wireless environment. Such wireless diversity is mainly composed of 2G/3G/4G cellular base stations, IEEE 802.11 hotspots and Community Networks. Previous work suggests that the increasing popularity of IEEE 802.11 networks would mitigate the overloading of current operator-based cellular deployments. However, the unpredictable characteristics of IEEE 802.11 deployments and its loose coupling to cellular architectures limit its user performance in terms of throughput and mobility capacity. In this paper, we describe an evaluation study of a commercial-grade hotspot network in the city of Luxembourg, namely HOTCITY. Through a set of experiments, we provide a characterization of the hotspot network and give a set of performance indicators. Finally, we evaluate hotspot networks' potential to support cellular offloading through the integration of outdoor hotspots and private access points deployed indoors in a single Community Network. [less ▲]

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See detailImproving Traffic in Urban Environments applying the Wardrop Equilibrium
Codeca, Lara UL; Frank, Raphaël UL; Engel, Thomas UL

in Improving Traffic in Urban Environments applying the Wardrop Equilibrium (2013, October 07)

Over the last few years vehicular traffic density has continuously increased and it is likely that the traffic demand will further increase in the future. In many metropolitan areas the road ... [more ▼]

Over the last few years vehicular traffic density has continuously increased and it is likely that the traffic demand will further increase in the future. In many metropolitan areas the road infrastructure is no longer able to handle the peak traffic demand and the existing road network cannot be easily extended. The best way to improve the traffic situation is to optimise the resources available in the transportation network and to coordinate the traffic demand. The approach that we propose in this paper makes use of a collaborative traffic coordination protocol which collects real-time Floating Car Data (FCD) directly from participating vehicles and suggests dynamic routes in order to minimize travel delay. Information such as speed, position and direction is sent to one or more Traffic Coordination Points (TCPs) where it is aggregated to obtain a global picture of the traffic conditions in real-time. Based on this data, we continuously compute the route that minimizes the travel time to a given destination by applying Wardrop’s first principle of equilibrium. Our results show that, by coordinating the vehicles, we are able to better distribute the overall traffic demand throughout the transportation network, reducing the average travel times and accommodating more vehicles. [less ▲]

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See detailAutomated Source Code Extension for Debugging of OpenFlow based Networks
Hommes, Stefan UL; Hermann, Frank UL; State, Radu UL et al

in Proc. 9th International Conference on Network and Service Management (CNSM) (2013, October)

Software-Defined Networks using OpenFlow have to provide a reliable way to to detect network faults in operational environments. Since the functionality of such networks is mainly based on the installed ... [more ▼]

Software-Defined Networks using OpenFlow have to provide a reliable way to to detect network faults in operational environments. Since the functionality of such networks is mainly based on the installed software, tools are required in order to determine software bugs. Moreover, network debugging might be necessary in order to detect faults that occurred on the network devices. To determine such activities, existing controller programs must be extended with the relevant functionality. In this paper we propose a framework that can modify controller programs transparently by using graph transformation, making possible online fault management through logging of network parameters in a NoSQL database. Latter acts as a storage system for flow entries and respective parameters, that can be leveraged to detect network anomalies or to perform forensic analysis. [less ▲]

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See detailDriver diaries: a multimodal mobility behaviour logging methodology
Kracheel, Martin UL; McCall, Roderick UL; Koenig, Vincent UL et al

in Proceedings of the 5th International Conference on Automotive User Interfaces and Interactive Vehicular Applications (2013, October)

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See detailIdentifying abnormal pattern in cellular communication flows
Goergen, David UL; Mendiratta, Veena; State, Radu UL et al

in Proceedings of IPTComm 2013 (2013, October)

Analyzing communication flows on the network can help to improve the overall quality it provides to its users and allow the operators to detect abnormal patterns and react accordingly. In this paper we ... [more ▼]

Analyzing communication flows on the network can help to improve the overall quality it provides to its users and allow the operators to detect abnormal patterns and react accordingly. In this paper we consider the analysis of large volumes of cellular communications records. We propose a method that detects abnormal communications events covering call data record volumes, comprising a country-level data set. We detect patterns by calculating a weighted average using a sliding window with a fixed period and correlate the results with actual events happening at that time. We are able to successfully detect several events using a data set provided by a mobile phone operator, and suggest examples of future usage of the outcome such as real time pattern detection and possible visualisation for mobile phone operators. [less ▲]

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See detailDriver Behavior Profiling using Smartphones
Castignani, German UL; Frank, Raphaël UL; Engel, Thomas UL

in Driver Behavior Profiling using Smartphones (2013, October)

The proliferation of smartphones and mobile devices embedding different types of sensors sets up a prodigious and distributed sensing platform. In particular, in the last years there has been an ... [more ▼]

The proliferation of smartphones and mobile devices embedding different types of sensors sets up a prodigious and distributed sensing platform. In particular, in the last years there has been an increasing necessity to monitor drivers to identify bad driving habits in order to optimize fuel consumption, to reduce CO2 emissions or, indeed, to design new reliable and fair pricing schemes for the insurance market. In this paper, we analyze the driver sensing capacity of smartphones. We propose a mobile tool that makes use of the most common sensors embedded in current smartphones and implement a Fuzzy Inference System that scores the overall driving behavior by combining different fuzzy sensing data. [less ▲]

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See detailClassification of Log Files with Limited Labeled Data
Hommes, Stefan UL; State, Radu UL; Engel, Thomas UL

in Proceedings of IPTComm 2013 (2013, October)

We address the problem of anomaly detection in log files that consist of a huge number of records. In order to achieve this task, we demonstrate label propagation as a semi-supervised learning technique ... [more ▼]

We address the problem of anomaly detection in log files that consist of a huge number of records. In order to achieve this task, we demonstrate label propagation as a semi-supervised learning technique. The strength of this approach lies in the small amount of labelled data that is needed to label the remaining data. This is an advantage since labelled data needs human expertise which comes at a high cost and be- comes infeasible for big datasets. Even though our approach is generally applicable, we focus on the detection of anoma- lous records in firewall log files. This requires a separation of records into windows which are compared using different distance functions to determine their similarity. Afterwards, we apply label propagation to label a complete dataset in only a limited number of iterations. We demonstrate our approach on a realistic dataset from an ISP. [less ▲]

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See detailAn Evaluation Study of Driver Profiling Fuzzy Algorithms using Smartphones
Castignani, German UL; Frank, Raphaël UL; Engel, Thomas UL

in An Evaluation Study of Driver Profiling Fuzzy Algorithms using Smartphones (2013, October)

Profiling driving behavior has become a relevant aspect in fleet management, automotive insurance and eco-driving. Detecting inefficient or aggressive drivers can help reducing fleet degradation ... [more ▼]

Profiling driving behavior has become a relevant aspect in fleet management, automotive insurance and eco-driving. Detecting inefficient or aggressive drivers can help reducing fleet degradation, insurance policy cost and fuel consumption. In this paper, we present a Fuzzy-Logic based driver scoring mechanism that uses smartphone sensing data, including accelerometers and GPS. In order to evaluate the proposed mechanism, we have collected traces from a testbed consisting in 20 vehicles equipped with an Android sensing application we have developed to this end. The results show that the proposed sensing variables using smartphones can be merged to provide each driver with a single score. [less ▲]

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See detailAdvanced Detection Tool for PDF Threats
Jerome, Quentin UL; Marchal, Samuel UL; State, Radu UL et al

in Proceedings of the sixth International Workshop on Autonomous and Spontaneous Security, RHUL, Egham, U.K., 12th-13th September 2013 (2013, September 13)

In this paper we introduce an efficient application for malicious PDF detection: ADEPT. With targeted attacks rising over the recent past, exploring a new detection and mitigation paradigm becomes ... [more ▼]

In this paper we introduce an efficient application for malicious PDF detection: ADEPT. With targeted attacks rising over the recent past, exploring a new detection and mitigation paradigm becomes mandatory. The use of malicious PDF files that exploit vulnerabilities in well-known PDF readers has become a popular vector for targeted at- tacks, for which few efficient approaches exist. Although simple in theory, parsing followed by analysis of such files is resource-intensive and may even be impossible due to several obfuscation and reader-specific artifacts. Our paper describes a new approach for detecting such malicious payloads that leverages machine learning techniques and an efficient feature selection mechanism for rapidly detecting anomalies. We assess our approach on a large selection of malicious files and report the experimental performance results for the developed prototype. [less ▲]

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See detailPath Extension Analysis of Peer-to-Peer Communications in 6LoWPAN/RPL Sensor Networks
Melakessou, Foued UL; Engel, Thomas UL

in Abstract book of 21st International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems, MASCOTS’13 (2013)

Researchers and manufacturers are currently putting a lot of efforts to design, improve and deploy the Internet of Things, involving a significant number of constrained and low cost embedded devices ... [more ▼]

Researchers and manufacturers are currently putting a lot of efforts to design, improve and deploy the Internet of Things, involving a significant number of constrained and low cost embedded devices deployed in large scales with low power consumption, low bandwidth and limited communication range. For instance we can easily build a network composed by multiple sensors distributed in a building in order to monitor temperature in different offices. This kind of architecture is generally centralized as all sensors are mainly programmed to periodically transmit their data to the sink. The specific IPv6 Routing Protocol for Low-power and Lossy Networks (RPL) had been designed in order to enable such communications. Support for point-to-point traffic is also available. In fact new applications may also consider peer-to-peer communications between any nodes of the network. In that case, RPL is not optimal as data packets are forwarded in respect with longer paths with larger metrics. In this paper we propose to study the effectiveness of RPL compared to a shortest path algorithm such like the Dijkstra's algorithm. We suggest to analyze peer-to-peer communications inside random wireless sensor network topologies with size limited to 250 nodes, corresponding to a reasonable cluster size. We have built a particular simulation environment named Network Analysis and Routing eVALuation (NARVAL). This toolbox permits to generate random topologies in order to study the impact of routing algorithms on the effectiveness of communication protocols. In our work, we first generated many random network topologies where we selected a sink node. We built the Destination Oriented Directed Acyclic Graph (DODAG) from the chosen sink in respect with the RPL algorithm. We finally performed all paths between each couple of two distinct sensor nodes and compared them to the corresponding shortest paths obtained by the Dijkstra's algorithm. This approach permits to retrieve some statistics on the path extension between RPL and the Dijkstra's algorithm. We also analyzed the impact of the sink position and the network size on this path extension. [less ▲]

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See detailA semantic firewall for Content Centric Networking
Goergen, David UL; Cholez, Thibault UL; François, Jérôme UL et al

in IFIP/IEEE International Symposium on Integrated Network Management (2013, May)

Content-Centric Networking (CCN) is a promising routing paradigm for content dissemination over a future Internet based on named data instead of named hosts. The CCN architecture has aspects that provide ... [more ▼]

Content-Centric Networking (CCN) is a promising routing paradigm for content dissemination over a future Internet based on named data instead of named hosts. The CCN architecture has aspects that provide more scalability, security, collaborative and pervasive networking. However, several key components that secures the current Internet are still missing in CCN, in particular a firewall able to enforce security policies. We provide a comprehensive study of CCN security requirements from which we design the first CCN-compliant firewall, including syntax and definition of rules. In particular, based on CCN features, our firewall can filter packets according to both their authentication and the semantics of the content name. We also provide a performance evaluation of our prototype. [less ▲]

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See detailModel synchronization based on triple graph grammars: correctness, completeness and invertibility
Hermann, Frank UL; Ehrig, Hartmut; Orejas, Fernando et al

in Software and Systems Modeling (2013)

Triple graph grammars (TGGs) have been used successfully to analyze correctness and completeness of bidirectional model transformations, but a corresponding formal approach to model synchronization has ... [more ▼]

Triple graph grammars (TGGs) have been used successfully to analyze correctness and completeness of bidirectional model transformations, but a corresponding formal approach to model synchronization has been missing. This paper closes this gap by providing a formal synchronization framework with bidirectional update propagation operations. They are generated from a given TGG, which specifies the language of all consistently integrated source and target models. As our main result, we show that the generated synchronization framework is correct and complete, provided that forward and backward propagation operations are deterministic. Correctness essentially means that the propagation operations preserve and establish consistency while completeness ensures that the operations are defined for all possible inputs. Moreover, we analyze the conditions under which the operations are inverse to each other. All constructions and results are motivated and explained by a running example, which leads to a case study, using concrete visual syntax and abstract syntax notation based on typed attributed graphs. [less ▲]

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See detailMulti-dimensional Aggregation for DNS Monitoring'
Dolberg, Lautaro UL; François, Jérôme UL; Engel, Thomas UL

in Proceedings of the 26th Large Installation System Administration Conference (LISA 12) (2013)

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See detailASMATRA: Ranking ASs Providing Transit Service to Malware Hosters
Wagner, Cynthia UL; François, Jérôme UL; State, Radu UL et al

in IFIP/IEEE International Symposium on Integrated Network Management IM2013 (2013)

The Internet has grown into an enormous network offering a variety of services, which are spread over a multitude of domains. BGP-routing and Autonomous Systems (AS) are the key components for maintaining ... [more ▼]

The Internet has grown into an enormous network offering a variety of services, which are spread over a multitude of domains. BGP-routing and Autonomous Systems (AS) are the key components for maintaining high connectivity in the Internet. Unfortunately, Internet Service Providers (ISPs) operating ASs do not only host normal users and content, but also malicious content used by attackers for spreading malware, hosting phishing web-sites or performing any kind of fraudulent activity. Practical analysis shows that such malware-providing ASs prevent themselves from being de-peered by hiding behind other ASs, which do not host the malware themselves but simply provide transit service for malware. This paper presents a new method for detecting ASs that provide transit service for malware hosters, without being malicious themselves. A formal definition of the problem and the metrics are determined by using the AS graph. The PageRank algorithm is applied to improve the scalability and the completeness of the approach. The method is assessed on real and publicly available datasets, showing promising results. [less ▲]

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See detailTowards Bidirectional Engineering of Satellite Control Procedures Using Triple Graph Grammars
Gottmann, Susann UL; Hermann, Frank UL; Ermel, Claudia et al

in Jacquet, Christophe; Balasubramanian, Daniel; Jones, Edward (Eds.) et al Proc. Int. Workshop on Multi-Paradigm Modeling 2013 (MPM'13) (2013)

The development and maintenance of satellite control software are very complex, mission-critical and cost-intensive tasks that require expertise from different domains. In order to adequately address ... [more ▼]

The development and maintenance of satellite control software are very complex, mission-critical and cost-intensive tasks that require expertise from different domains. In order to adequately address these challenges, we propose to use visual views of the software to provide concise abstractions of the system from different perspectives. This paper introduces a visual language for process flow models of satellite control procedures that we developed in cooperation with the industrial partner SES for the satellite control language SPELL. Furthermore, we present a general and formal bidirectional engineering approach for automatically translating satellite control procedures into corresponding process flow visualisations. The bidirectional engineering framework is supported by a visual editor based on Eclipse GMF, the transformation tool HenshinTGG, and additional extensions to meet requirements set up by the specific application area of satellite control languages. [less ▲]

Detailed reference viewed: 107 (21 UL)