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Filtering by: Creator Kranakis, Evangelos Remove constraint Creator: Kranakis, Evangelos Date Created 2010 Remove constraint Date Created: 2010

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  • On minimizing the sum of sensor movements for barrier coverage of a line segment

    Resource Type:
    Conference Proceeding
    Creator:
    Czyzowicz, Jurek, Opatrny, Jaroslav, Kranakis, Evangelos, Narayanan, Lata, Krizanc, Danny, Stacho, Ladislav, Urrutia, Jorge, Yazdani, Mohammadreza, and Lambadaris, Ioannis
    Abstract:
    A set of sensors establishes barrier coverage of a given line segment if every point of the segment is within the sensing range of a sensor. Given a line segment I, n mobile sensors in arbitrary initial positions on the line (not necessarily inside I) and the sensing ranges of the sensors, we are interested in finding final positions of sensors which establish a barrier coverage of I so that the sum of the distances traveled by all sensors from initial to final positions is minimized. It is shown that the problem is NP complete even to approximate up to constant factor when the sensors may have different sensing ranges. When the sensors have an identical sensing range we give several efficient algorithms to calculate the final destinations so that the sensors either establish a barrier coverage or maximize the coverage of the segment if complete coverage is not feasible while at the same time the sum of the distances traveled by all sensors is minimized. Some open problems are also mentioned.
    Date Created:
    2010-12-13

  • Security threat mitigation trends in low-cost RFID systems

    Resource Type:
    Conference Proceeding
    Creator:
    Barbeau, Michel, Kranakis, Evangelos, and Garcia-Alfaro, Joaquin
    Abstract:
    The design and implementation of security threat mitigation mechanisms in RFID systems, specially in low-cost RFID tags, are gaining great attention in both industry and academia. One main focus of research interests is the authentication and privacy techniques to prevent attacks targeting the insecure wireless channel of these systems. Cryptography is a key tool to address these threats. Nevertheless, strong hardware constraints, such as production costs, power consumption, time of response, and regulations compliance, makes the use of traditional cryptography in these systems a very challenging problem. The use of low-overhead procedures becomes the main approach to solve these challenging problems where traditional cryptography cannot fit. Recent results and trends, with an emphasis on lightweight techniques for addressing critical threats against low-cost RFID systems, are surveyed.
    Date Created:
    2010-05-03

  • Distributed storage in disruption tolerant network

    Resource Type:
    Conference Proceeding
    Creator:
    Nayak, Amiya, Du, Jingzhe, and Kranakis, Evangelos
    Abstract:
    We describe a novel Distributed Storage protocol in Disruption (Delay) Tolerant Networks (DTN). Since DTNs can not guarantee the connectivity of the network all the time, distributed data storage and look up has to be performed in a store-and-forward way. In this work, we define local distributed location regions which are called cells to facilitate the data storage and look up process. Nodes in a cell have high probability of moving within their cells. Our protocol resorts to storing data items in cells which have hierarchical structure to reduce routing information storage at nodes. Multiple copies of a data item may be stored at nodes to counter the adverse impact of the nature of DTNs. The cells are relatively stable regions and as a result, data exchange overheads among nodes are reduced. Through experimentation, we show that the proposed distributed storage protocol achieves higher successful data storage ratios with lower delays and limited data item exchange requirements than other protocols in the literature.
    Date Created:
    2010-08-27