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Wireless Sensor Networks, 2005. Proceeedings of the Second European Workshop on

Date 31 Jan.-2 Feb. 2005

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Displaying Results 1 - 25 of 56
  • A prototype sensor node for footstep detection

    Page(s): 415 - 418
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    Persons moving over ground can be detected from vibrations induced to soil in the form of seismic waves which are measured by geophones or expensive MEMS accelerometers. We are proposing a sensor node that uses a low-cost bending mode piezoelectric accelerometer, operating near its resonant frequency, specially designed for footstep detection. View full abstract»

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  • Flexible hardware abstraction for wireless sensor networks

    Page(s): 145 - 157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    We present a flexible hardware abstraction architecture (HAA) that balances conflicting requirements of wireless sensor networks (WSNs) applications and the desire for increased portability and streamlined development of applications. Our three-layer design gradually adapts the capabilities of the underlying hardware platforms to the selected platform-independent hardware interface between the operating system core and the application code. At the same time, it allows the applications to utilize a platform's full capabilities-exported at the second layer, when the performance requirements outweigh the need for cross-platform compatibility. We demonstrate the practical value of our approach by presenting how it can be applied to the most important hardware modules that are found in a typical WSN platform. We support our claims using concrete examples from existing hardware abstractions in TinyOS and our implementation of the MSP430 platform that follows the architecture proposed in this paper. View full abstract»

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  • OLIMPO, an ad-hoc wireless sensor simulator for public utilities applications

    Page(s): 419 - 424
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    This paper introduces OLIMPO, an useful simulation tool for researchers who are developing wireless sensor communication protocols. OLIMPO is a discrete-event simulator design to be easily reconfigured by the user, providing a way to design, develop and test communication protocols. In particular, we have designed a self-organizing wireless sensor network for low data rate. Our premise is that, due to their inherent spread location over large areas, wireless sensor networks are well-suited for SCADA applications, which require relatively simple control and monitoring. To show the facilities of our simulator, we have studied our network protocol with OLIMPO, developing several simulations. The purpose of these simulations is to demonstrate, quantitatively, the capability of our network to support this kind of applications. View full abstract»

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  • TASK: sensor network in a box

    Page(s): 133 - 144
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (707 KB) |  | HTML iconHTML  

    Sensornet systems research is being conducted with various applications and deployment scenarios in mind. In many of these scenarios, the presumption is that the sensornet will be deployed and managed by users who do not have a background in computer science. In this paper we describe the "tiny application sensor kit" (TASK), a system we have designed for use by end-users with minimal sensornet sophistication. We describe the requirements that guided our design, the architecture of the system and results from initial deployments. Based on our experience to date we present preliminary design principles and research challenges that arise in delivering sensornet research to end users. View full abstract»

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  • Collaborative broadcasting and compression in cluster-based wireless sensor networks

    Page(s): 197 - 206
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    Achieving energy efficiency to prolong the network lifetime is an important design criterion for wireless sensor networks. In this paper, we propose a novel approach to conserve energy by allowing sensors to exploit the inherent broadcast nature of the wireless channel to carry out joint data compression. We illustrate this idea in a cluster-based wireless sensor network. The key idea is that when a particular sensor broadcasts its data to the cluster head, other sensors can receive and utilize that data to compress their own data. We formulate an optimization problem in which sensors in each cluster collaborate their transmitting, receiving and compressing activities to maximize their lifetime and solve for the optimal control scheme. By optimal, we mean that any other policy cannot increase the lifetime of the node which dies first. We also propose a heuristic scheme with lower complexity and near optimal performance. Numerical results show that by exploiting the broadcast nature of wireless media, our control schemes can achieve significant improvement in the sensors' lifetime. View full abstract»

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  • An algorithmic framework for robust access control in wireless sensor networks

    Page(s): 158 - 165
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB) |  | HTML iconHTML  

    If the data collected within a sensor network is valuable or should be kept confidential then security measures should protect the access to this data. We first determine security issues in the context of access control in sensor networks especially focusing on the problem of node capture, i.e., the possibility that an attacker can completely take over some of the sensor nodes. We then introduce the notion of t-robust sensor networks which can withstand capture of up to t nodes and consider three basic security concepts for such networks: (1) t-robust storage, a mechanism to securely store data within a set of sensors such that capture of any t sensors does not reveal that data to the adversary; (2) n-authentication which ensures that authentication is achieved with every uncompromised sensor in the broadcast range of a client (n denotes the number of nodes in that broadcast range); and (3) n-authorization, an authorization primitive with similar properties like n-authentication. We present a generic t-robust protocol for implementing access control using these primitives. View full abstract»

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  • High-density wireless sensor networks: a new clustering approach for prediction-based monitoring

    Page(s): 188 - 196
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB) |  | HTML iconHTML  

    We propose a new cluster-based approach that simplifies prediction-based monitoring for homogeneous, high-density wireless sensor networks composed of a large number of small, power-restricted nodes. Prediction-based monitoring can increase the autonomous lifetime of the network by reducing communication. In our clustering approach, the cluster-heads spatio-temporally correlate and predict the measurements of the cluster-members by executing their prediction model. Routing is only done by the gateway nodes at the circumference of the clusters while the nongateway nodes, which are positioned between the cluster-heads and their gateway nodes, are allowed to turn off their radio communication as long as their measurements satisfy the predictions of their cluster-head. Turning off radio communication results in high energy savings and can greatly improve system lifetime. Our main contribution is the description of this clustering approach while the prediction models are beyond the scope of this paper. View full abstract»

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  • μ-MAC: an energy-efficient medium access control for wireless sensor networks

    Page(s): 70 - 80
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    For the long-term deployment of wireless sensor networks, energy efficient MAC protocols are necessary. The transceiver of a sensor node should only consume energy while actively taking part in communication. Energy consumption in idle mode should be avoided as much as possible. In this paper it is shown how application layer knowledge in the form of flow specifications can be used to improve the energy properties of a MAC protocol. A new protocol, named μ-MAC, is proposed and evaluated through simulations. View full abstract»

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  • Remote incremental linking for energy-efficient reprogramming of sensor networks

    Page(s): 354 - 365
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (715 KB) |  | HTML iconHTML  

    With sensor networks expected to be deployed for long periods of time, the ability to reprogram them remotely is necessary for providing new services, fixing bugs and enhancing applications and system software. Given the envisioned scales of future sensor network deployments, their restricted accessibility and the limited energy and computing resources of sensors, transmitting raw binary images is inefficient. We present a technique to minimize the cost of application evolution by remotely and incrementally linking updated modules at the base station and distributing deltas of the prelinked software modules. This paper provides details of our implementation, some preliminary results and surveys critical research issues in developing a comprehensive framework for reprogramming sensor networks. View full abstract»

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  • SeFER: secure, flexible and efficient routing protocol for distributed sensor networks

    Page(s): 246 - 255
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB) |  | HTML iconHTML  

    In this paper, we present a secure, flexible, and efficient routing protocol for sensor networks based on random key predistribution. Our protocol aims to establish secure paths in a sensor network between a controller and a set of nodes where each node has been assigned a set of randomly chosen keys out of a key pool. A common model for sensor networks assumes a tree of sensor nodes delivering information to the controller according to an inquiry sent into the network. However, these two nodes may communicate indirectly but securely over a multiple hop path where each pair of nodes on this path shares a common key. Our protocol bridges the gap between these two cases by providing the methods for nodes to securely share their keys and communicate directly so that the efficiency of communications is increased without jeopardizing the security. In this way, our protocol generates secure and efficient routes. We also provide simulation results for our protocol demonstrating that, for a small number of keys stored at each node, the average path length is smaller. However, the gains due to our protocol diminish as the number of available keys at each node increases since two nodes within communication range of each other are more likely to have a key in common. View full abstract»

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  • Algorithm for optimizing energy use and path resilience in sensor networks

    Page(s): 391 - 396
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    Sensor networks will change the way computers interface with our world and with each other. This transformation will be shaped by the network centric paradigm demonstrated in sensor networks. Sensor networks also require a data-centric communication paradigm to efficiently and effectively share data. Directed diffusion is a data-centric communication paradigm that forms a foundation of this paper. Energy efficient routing algorithms have been developed for directed diffusion; however, we have developed improved algorithms, which are described in this paper. We also present computer simulation results, which verify the effectiveness of previously established routing algorithms and compare them to our new and improved routing algorithms. The results show significant increase in energy efficiency and resilience. Finally, the paper incorporates effective techniques for modeling of sensor networks to demonstrate the usefulness of the new algorithms. View full abstract»

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  • Localization in nonline-of-sight environments for wireless sensor networks

    Page(s): 410 - 414
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (230 KB) |  | HTML iconHTML  

    In this paper we present a ranging algorithm for indoor quasistatic sensor environments based on statistical modeling of the multipath channel. Based on the noise and LOS characterization from this model, we use multiple returns (or signal receptions) at each sensor node to accurately estimate the position of the direct path or line-of-sight (LOS) component in the received multipath signal. This provides range estimates with submeter accuracy. Furthermore, the associated ranging error does not increase with increase in the transmitter-receiver range. View full abstract»

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  • Nomadic sensor networks

    Page(s): 166 - 175
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (543 KB) |  | HTML iconHTML  

    Wireless sensor networks (WSN) have been investigated in their various forms over the last years as they are considered to be a major step towards pervasive computing. Nevertheless, except for military applications WSNs can be found only as 'proof of concept'. Within this paper we analyze the current situation and explain what we call the dilemma of WSN. We show the consequences of the various choices for the sensor node design and propose nomadic sensor networks as a way to introduce sensors into our everyday life in an incremental and cost-effective way. We show the general feasibility of this concept by presenting preliminary analytic and simulation based results, using a simple parking scenario for demonstration purposes. View full abstract»

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  • A biologically-inspired clustering algorithm dependent on spatial data in sensor networks

    Page(s): 386 - 390
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    Sensor networks in environmental monitoring applications aim to provide scientists with a useful spatio-temporal representation of the observed phenomena. This helps to deepen their understanding of the environmental signals that cover large geographic areas. In this paper, the spatial aspect of this data handling requirement is met by creating clusters in a sensor network based on the rate of change of an oceanographic signal with respect to space. Inspiration was drawn from quorum sensing, a biological process that is carried out within communities of bacterial cells. The paper demonstrates the control the user has over the sensitivity of the algorithm to the data variation and the energy consumption of the nodes while they run the algorithm. View full abstract»

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  • Sensation: a middleware integration platform for pervasive applications in wireless sensor networks

    Page(s): 366 - 377
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    In this paper we focus on the issue of application development for wireless sensor networks (WSN). Currently, such networks are extensively used in various business domains. However, their highly customized operating systems and application middleware render the application development for multiple WSNs rather cumbersome. Applications based on multiple WSNs are typical in the emerging pervasive computing paradigm adopted in numerous domains (e.g., telemedicine). A WSN can be considered as a source of information similarly to a database. Motivated by the layered driver approach introduced in the ODBC/JDBC frameworks, we propose a middleware integration architecture. Our architecture presents a unified and developer-friendly interface and abstract data model towards the application. Such interface conceals the peculiarities of the underlying WSNs as their coordination and data retrieval software is integrated in the lower layer of the proposed middleware framework. We present the design of the discussed architecture that is based on open standards like XML. View full abstract»

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  • Monitoring volcanic eruptions with a wireless sensor network

    Page(s): 108 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (674 KB) |  | HTML iconHTML  

    This paper describes our experiences using a wireless sensor network to monitor volcanic eruptions with low-frequency acoustic sensors. We developed a wireless sensor array and deployed it in July 2004 at Volcan Tingurahua, an active volcano in central Ecuador. The network collected infrasonic (low-frequency acoustic) signals at 102 Hz, transmitting data over a 9 km wireless link to a remote base station. During the deployment, we collected over 54 hours of continuous data which included at least 9 large explosions. Nodes were time-synchronized using a separate GPS receiver, and our data was later correlated with that acquired at a nearby wired sensor array. In addition to continuous sampling, we have developed a distributed event detector that automatically triggers data transmission when a well-correlated signal is received by multiple nodes. We evaluate this approach in terms of reduced energy and bandwidth usage, as well as accuracy of infrasonic signal detection. View full abstract»

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  • An energy efficient scatternet formation algorithm for Bluetooth-based sensor networks

    Page(s): 207 - 216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (483 KB) |  | HTML iconHTML  

    In this paper, we propose an energy-efficient scatternet formation algorithm for Bluetooth based sensor networks. The algorithm is based on first computing a shortest path tree from the base station to all sensor nodes and then solving the degree constraint problem so that the degree of each node in the network is not greater than seven, which is a Bluetooth constraint. In this way, less amount of energy is spent in each round of communication in the sensor network. The algorithm also tries to balance the load evenly on the high-energy consuming nodes which are the nodes that are close to the base station. In this way, the lifetime of the first dying node is also prolonged. We obtained promising results in the simulations. View full abstract»

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  • Integrated design of STBC-based virtual-MIMO and distributed compression in energy-limited wireless sensor networks

    Page(s): 267 - 277
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    An integrated design of a joint distributed source coding and an adaptive signal processing scheme for a virtual multiple input multiple output (V-MIMO) communications-based, cooperative wireless sensor network is proposed. We employ a distributed coding scheme that exploits inherent correlations among sensor data and an adaptive correlation tracking technique based on recursive least squares (RLS) algorithm that provides improved energy efficiency compared to previously proposed such joint coding and signal processing schemes for single input single output (SISO) communications based systems. An integration scheme with virtual space-time block coding based M-ary quadrature amplitude modulation (M-QAM) communication is also developed. The system efficiency is analyzed for various transmission distances and various channel conditions. Our results show that the proposed system achieves significant energy savings compared to conventional designs beyond certain transmission distances. The achieved energy efficiencies and low decoding error rates justify the application of the proposed scheme in energy constrained wireless sensor networks. View full abstract»

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  • Energy supply considerations for self-sustaining wireless sensor networks

    Page(s): 397 - 399
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    The challenges of designing a power supply including generation, storage and conversion are manifold and design problems are difficult to solve with off-the-shelf hardware components. One has to think about losses all the time when overall leakage currents of less than a few microamperes are desired. In general, reducing the complexity of the circuit reduces the power consumption as well, but efficient charging of an energy storage element such as a battery or ultracapacitor becomes difficult. Finding a well-balanced point where sum of leakage current and charging losses reaches a minimum is the way to go. This paper discusses this issues and shows some diagrams and solutions to the power supply problem one is confronted with, when designing energy self-sufficient sensor nodes. View full abstract»

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  • A biologically-inspired approach to designing wireless sensor networks

    Page(s): 256 - 266
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    In this paper, we contend that there are significant advantages in treating some classes of sensor networks as biological-like systems-both in structural design characteristics and in operational processes. We show how this design process leads to a sensor network system that is robust to topological changes, is scaleable and self-organising and has a number of other desirable features. The operating system kOS was designed to support the operation of distributed biologically-inspired algorithms, in order to accomplish tasks in a sensor network system. We look at the design of kOS and analyse its performance. The work presented has been implemented in an environmental monitoring project and has applications in other areas. View full abstract»

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  • Localizing a sensor network via collaborative processing of global stimuli

    Page(s): 321 - 332
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    In order for nodes in a sensor network to meaningfully correlate their sensor readings, they must first determine their position in a globally shared coordinate system. Though there are many approaches which are suitable for achieving localization in the general case, sensor nodes are uniquely suited to use their sensing capabilities to aid them in this task. Global events which are detected in the environment surrounding the sensor network can serve as points of correspondence which, through collaborative processing on the network, provide nodes with sufficient information to compute their position. We have implemented an algorithm based on this approach in the Pushpin Computing sensor network: a dense, 55 node network which is spread over an area of 0.5 square meters. By queuing off of the minimum number of ultrasound pulses and light flashes needed to determine 2D coordinates using a simple lateration approach, we show that nodes in the Pushpin network can compute their position with an average error of 5-cm and a error standard deviation of 3-cm. In this paper we present this localization system and characterize its accuracy in our hardware testbed. View full abstract»

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  • Impact of contention based MAC on the performance of a wireless sensor network for environmental monitoring

    Page(s): 400 - 404
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    An analytical framework to evaluate the performance of a dense energy-efficient wireless sensor network (WSN) enabling environment monitoring is developed in this paper. We address the estimation of a target multidimensional process by means of samples that are captured by nodes randomly and uniformly distributed and transmitted to a collector through a self-organizing clustered network. The WSN performance is defined in terms of both process estimation error and network lifetime. A new contention-based medium access control (MAC) protocol is introduced to reduce retransmissions. The impact of the proposed MAC strategy on the energy budget is shown. View full abstract»

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  • Link-layer jamming attacks on S-MAC

    Page(s): 217 - 225
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    We argue that among denial-of-service (DoS) attacks, link-layer jamming is a more attractive option to attackers than radio jamming is. By exploiting the semantics of the link-layer protocol (aka MAC protocol), an attacker can achieve better efficiency than blindly jamming the radio signals alone. In this paper, we investigate some jamming attacks on S-MAC, the level of effectiveness and efficiency the attacks can potentially achieve and a countermeasure that can be implemented against one of these attacks. View full abstract»

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  • Distributed construction of an underlay in wireless networks

    Page(s): 176 - 187
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    A wireless network consists of a large number of nodes that use wireless communication links to collectively perform certain tasks in various application domains (industry, military, etc.). Since wireless nodes are irregularly scattered over a large application area, a suitable wireless multihop routing protocol is needed to facilitate the communication between arbitrary nodes. Many geographic routing protocols use a planar graph as the underlying network topology. This paper presents an efficient algorithm for the localized computation of such an underlay, namely, the short Delaunay triangulation (SDT). The SDT contains all edges of the Delaunay triangulation that are shorter than the communication range. The great asset of the short Delaunay triangulation is its spanning property: It approximates the shortest path of the unit disk graph by a constant factor. Our distributed algorithm for constructing the SDT surpasses alternative underlay construction algorithms and requires point-to-point communication links only. View full abstract»

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  • TinyCubus: a flexible and adaptive framework sensor networks

    Page(s): 278 - 289
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (690 KB) |  | HTML iconHTML  

    With the proliferation of sensor networks and sensor network applications, the overall complexity of such systems is continuously increasing. Sensor networks are now heterogeneous in terms of their hardware characteristics and application requirements even within a single network. In addition, the requirements of currently supported applications are expected to change over time. All of this makes developing, deploying and optimizing sensor network applications an extremely difficult task. In this paper, we present the architecture of TinyCubus, a flexible and adaptive cross-layer framework for TinyOS-based sensor networks that aims at providing the necessary infrastructure to cope with the complexity of such systems. TinyCubus consists of a data management framework that selects and adapts both system and data management components, a cross-layer framework that enables optimizations through cross-layer interactions, and a configuration engine that installs components dynamically. Furthermore, we show the feasibility of our architecture by describing and evaluating a code distribution algorithm that uses application knowledge about the sensor topology in order to optimize its behavior. View full abstract»

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