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Sensor Network Protocols and Applications, 2003. Proceedings of the First IEEE. 2003 IEEE International Workshop on

Date 11-11 May 2003

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Displaying Results 1 - 19 of 19
  • Proceedings of the First IEEE International Workshop on Sensor Network Protocols and Applications (Cat. No.03EX698)

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    Freely Available from IEEE
  • Autor index

    Page(s): 174
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    Freely Available from IEEE
  • Aggregation in sensor networks: an energy-accuracy trade-off

    Page(s): 128 - 138
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    Wireless ad hoc sensor networks (WASNs) are in need of the study of useful applications that will help the researchers view them as distributed physically coupled systems, a collective that estimates the physical environment, and not just energy-limited ad hoc networks. We develop this perspective using a large and interesting class of WASN applications called aggregation applications. In particular, we consider the challenging periodic aggregation problem where the WASN provides the user with periodic estimates of the environment, as opposed to simpler and previously studied snapshot aggregation problems. In periodic aggregation our approach allows the spatial-temporal correlation among values sensed at the various nodes to be exploited towards energy-efficient estimation of the aggregated value of interest. Our approach also creates a system level energy vs. accuracy knob whereby the more the estimation error that the user can tolerate, the less is the energy consumed. We present a distributed estimation algorithm that can be applied to explore the energy-accuracy subspace for a sub-class of periodic aggregation problems, and present extensive simulation results that validate our approach. The resulting algorithm, apart from being more flexible in the energy-accuracy subspace and more robust, can also bring considerable energy savings for a typical accuracy requirement (five-fold decrease in energy consumption for 5% estimation error) compared to repeated snapshot aggregations. View full abstract»

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  • Target localization based on energy considerations in distributed sensor networks

    Page(s): 51 - 58
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    Wireless distributed sensor networks (DSNs) are important for a number of strategic applications such as coordinated target detection, surveillance, and localization. Energy is a critical resource in wireless sensor networks and system lifetime needs to be prolonged through the use of energy-conscious sensing strategies during system operation. We propose an energy-aware target detection and localization strategy for cluster-based wireless sensor networks. The proposed method is based on an a posteriori algorithm with a two-step communication protocol between the cluster head and the sensors within the cluster. Based on a limited amount of data received from the sensor nodes, the cluster head executes a localization procedure to determine the subset of sensors that must be queried for detailed target information. This approach reduces both energy consumption and communication bandwidth requirements, and prolongs the lifetime of the wireless sensor network. Simulation results show that a large amount of energy is saved during target localization using this strategy. View full abstract»

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  • DIFS: a distributed index for features in sensor networks

    Page(s): 163 - 173
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    Sensor networks pose new challenges in the collection and distribution of data. Much attention has been focused on standing queries that use in-network aggregation of time series data to return data statistics in a communication-efficient manner. In this work, rather than consider searches over time series data, we consider searches over semantically rich high-level events, and present the design, analysis, and numerical simulations of a spatially distributed index that provides for efficient index construction and range searches. The scheme provides load balanced communication over index nodes by using the governing property that the wider the spatial extent known to an index node, the more constrained is the value range covered by that node. View full abstract»

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  • Localized positioning in ad hoc networks

    Page(s): 42 - 50
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    Position centric approaches, such as Cartesian routing, geographic routing, and the recently proposed trajectory based forwarding (TBF), address scalability issues in large ad hoc networks by using Euclidean space as a complementary name space. These approaches require. that nodes know their position in a common coordinate system. While a GPS receiver in each node would be ideal, in many cases an approximation algorithm is necessary for networks with only a few GPS enabled nodes. These algorithms however require collaboration of large portions of the network, thus imposing an overhead for nodes which do not need positioning, or are mobile. We propose Local Positioning System (LPS), a method that makes use of local node capabilities-angle of arrival, range estimations, compasses and accelerometers, in order to internally position only the groups of nodes involved in particular conversations. Localized positioning enables position centric uses, like discovery, flooding and routing in networks where global positioning is not available. View full abstract»

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  • Localized edge detection in sensor fields

    Page(s): 59 - 70
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    A wireless sensor network that studies relatively widespread phenomena (such as a contaminant flow or a seismic disturbance) may be called upon to provide a description of the boundary of the phenomenon (either a contour or some bounding box). In such cases, it may be necessary for each node to locally determine whether it lies at (or near) the edge of the phenomenon. In this paper, we show that such localized edge detection techniques are non-trivial to design in an arbitrarily deployed sensor network. We define the notion of an edge and develop performance metrics for evaluating localized edge detection algorithms. We propose three different approaches for localized edge detection and present one example scheme for each. In all our approaches, each sensor gathers information from its local neighborhood and determines whether or not it is an edge sensor. We evaluate the performance! of each of the example schemes and compare them with respect to the developed metrics. View full abstract»

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  • Computing aggregates for monitoring wireless sensor networks

    Page(s): 139 - 148
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    Wireless sensor networks involve very large numbers of small, low-power, wireless devices. Given their unattended nature, and their potential applications in harsh environments, we need a monitoring infrastructure that indicates system failures and resource depletion. We describe an architecture for sensor network monitoring, then focus on one aspect of this architecture: continuously computing aggregates (sum, average, count) of network properties (loss rates, energy-levels etc., packet counts). Our contributions are two-fold. First, we propose a novel tree construction algorithm that enables energy-efficient computation of some classes of aggregates. Second, we show through actual implementation and experiments that wireless communication artifacts in even relatively benign environments can significantly impact the computation of these aggregate properties. In some cases, without careful attention to detail, the relative error in the computed aggregates can be as much as 50%. However, by carefully discarding links with heavy packet loss and asymmetry, we can improve accuracy by an order of magnitude. View full abstract»

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  • Reliable upgrade of group communication software in sensor networks

    Page(s): 82 - 92
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    Communication is critical between nodes in wireless sensor networks. Upgrades to their communication software need to be done reliably because residual software errors in the new module can cause complete system failure. We present a software architecture, called cSimplex, which can reliably upgrade multicast-based group communication software in sensor networks. Errors in the new module are detected using statistical checks and a stability definition that we propose. Error recovery is done by switching to a well-tested, reliable safety module without any interruption in the functioning of the system. cSimplex has been implemented and demonstrated in a network of acoustic sensors with mobile robots functioning as base stations. Experimental results show that faults in the upgraded software can be detected with an accuracy of 99.71% on average. The architecture, which can be easily extended to other reliable upgrade problems, will facilitate a paradigm shift in system evolution from static design and extensive testing to reliable upgrades of critical communication components in networked systems, thus also enabling substantial savings in testing time and resources. View full abstract»

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  • Energy efficiency based packet size optimization in wireless sensor networks

    Page(s): 1 - 8
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    This paper addresses the question of optimal packet size for data communication in energy constrained wireless sensor networks. Unlike previous work on packet length optimization in other wired and wireless networks, energy efficiency is chosen as the optimization metric. The use of fixed size packets is proposed in light of the limited resources and management costs in sensor networks. The optimal fixed packet size is then determined for a set of radio and channel parameters by maximizing the energy efficiency metric. Further, the effect of error control on packet size optimization and energy efficiency is examined. While retransmission schemes are found to be energy inefficient, it is shown that forward error correction can improve the energy efficiency eventhough it introduces additional parity bits and encoding/decoding energy consumptions. In this regard, binary BCH codes are found to be 15% more energy efficient than the best performing convolutional codes, which have thus far been considered for error control in sensor networks. View full abstract»

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  • Data funneling: routing with aggregation and compression for wireless sensor networks

    Page(s): 156 - 162
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    This paper considers the problem of minimizing the amount of communication needed to send readings from a set of sensors to a single destination in energy constrained wireless networks. Substantial gains can be obtained using packet aggregation techniques while routing. The proposed routing algorithm, called Data Funneling, allows the network to considerably reduce the amount of energy spent on communication setup and control, an important concern in low data-rate communication. This is achieved by sending only one data stream from a group of sensors to the destination instead of having an individual data stream from each sensor to the destination. Doing so also reduces the probability of packet collisions in the wireless medium because the same amount of information can be transmitted by having fewer nodes send longer packets. Additional gains can be realized by efficient compression of data. This is achieved by losslessly compressing the data by encoding information in the ordering of the sensors' packets. This "coding by ordering" scheme compresses data by suppressing certain readings and encoding their values in the ordering of the remaining packets. Using these techniques together can more than halve the energy spent in communication. View full abstract»

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  • Secure routing in wireless sensor networks: attacks and countermeasures

    Page(s): 113 - 127
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    We consider routing security in wireless sensor networks. Many sensor network routing protocols have been proposed, but none of them have been designed with security as a goal. We propose security goals for routing in sensor networks, show how attacks against ad-hoc and peer-to-peer networks can be adapted into powerful attacks against sensor networks, introduce two classes of novel attacks against sensor networks sinkholes and HELLO floods, and analyze the security of all the major sensor network routing protocols. We describe crippling attacks against all of them and suggest countermeasures and design considerations. This is the first such analysis of secure routing in sensor networks. View full abstract»

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  • The ACQUIRE mechanism for efficient querying in sensor networks

    Page(s): 149 - 155
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    We propose a novel and efficient mechanism for obtaining information in sensor networks which we refer to as ACQUIRE. In ACQUIRE an active query is forwarded through the network, and intermediate nodes use cached local information (within a look-ahead of d hops) in order to partially resolve the query. When the query is fully resolved, a completed response is sent directly back to the querying node. We take a mathematical modelling approach in this paper to calculate the energy costs associated with ACQUIRE. The models permit us to characterize analytically the impact of critical parameters, and compare the performance of ACQUIRE with respect to alternatives such as flooding-based querying (FBQ) and expanding ring search (ERS). We show that with optimal parameter settings, depending on the update frequency, ACQUIRE obtains order of magnitude reduction over FBQ and potentially over 60% reduction over ERS in consumed energy. View full abstract»

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  • A protocol for tracking mobile targets using sensor networks

    Page(s): 71 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (670 KB) |  | HTML iconHTML  

    With recent advances in device fabrication technology, economical deployment of large scale sensor networks, capable of pervasive monitoring and control of physical systems have become possible. Scalability, low overhead anti distributed functionality are some of the key requirements for any protocol designed for such large scale sensor networks. In this paper, we present a protocol, Distributed Predictive Tracking, for one of the most likely applications for sensor networks: tracking moving targets. The protocol uses a clustering based approach for scalability and a prediction based tracking mechanism to provide a distributed and energy efficient solution. The protocol is robust against node or prediction failures which may result in temporary loss of the target and recovers from such scenarios quickly and with very little additional energy use. Using simulations we show that the proposed architecture is able to accurately track targets with random movement patterns with accuracy over a wide range of target speeds. View full abstract»

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  • Multi-resolution state retrieval in sensor networks

    Page(s): 19 - 29
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    Large-scale dense sensor networks require mechanisms to extract topology information that can be used for various aspects of sensor network management. It is critical for any topology discovery algorithm in dense networks not only to adhere to the resource constraints of bandwidth and energy but also to provide several views of the network. Due to factors of density, redundancy and failures it may not be possible or practical to get a complete view of the topology. We describe a distributed parameterized algorithm for Sensor Topology Retrieval at Multiple Resolutions (STREAM), which makes a tradeoff between topology details and resources expended. The algorithm retrieves network state at multiple resolutions at a proportionate communication cost. We also define various classes of topology queries and show how the parameters in the algorithm can be used to support queries specific to sensor networks. We show that topology determined at different resolutions is sufficient for approximating different network properties. We also show that STREAM can be used for general-purpose multi-resolution information retrieval in sensor networks. View full abstract»

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  • RMST: reliable data transport in sensor networks

    Page(s): 102 - 112
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    Reliable data transport in wireless sensor networks is a multifaceted problem influenced by the physical, MAC, network, and transport layers. Because sensor networks are subject to strict resource constraints and are deployed by single organizations, they encourage revisiting traditional layering and are less bound by standardized placement of services such as reliability. This paper presents analysis and experiments resulting in specific recommendations for implementing reliable data transport in sensor nets. To explore reliability at the transport layer, we present RMST (Reliable Multi-Segment Transport), a new transport layer for Directed Diffusion. RMST provides guaranteed delivery and fragmentation/reassembly for applications that require them. RMST is a selective NACK-based protocol that can be configured for in-network caching and repair. View full abstract»

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  • Data MULEs: modeling a three-tier architecture for sparse sensor networks

    Page(s): 30 - 41
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    This paper presents and analyzes an architecture to collect sensor data in sparse sensor networks. Our approach exploits the presence of mobile entities (called MULEs) present in the environment. MULEs pick up data from the sensors when in close range, buffer it, and drop off the data to wired access points. This can lead to substantial power savings at the sensors as they only have to transmit over a short range. This paper focuses on a simple analytical model for understanding performance as system parameters are scaled. Our model assumes two-dimensional random walk for mobility and incorporates key system variables such as number of MULEs, sensors and access points. The performance metrics observed are the data success rate (the fraction of generated data that reaches the access points) and the required buffer capacities on the sensors and the MULEs. The modeling along with simulation results can be used for further analysis and provide certain guidelines for deployment of such systems. View full abstract»

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  • Optimal energy-balanced algorithm for selection in a single hop sensor network

    Page(s): 9 - 18
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    Sensor networks are being used to implement a large set of applications that require distributed, collaborative computations. Selection is an important kernel in several sensor applications, particularly those involving speech and image data processing. In this paper we present an energy and time optimal algorithm for the selection problem in a single hop wireless network. The algorithm also has the property that it is energy-balanced. This implies that all sensors dissipate asymptotically equal amount of energy. Uniform energy dissipation is desirable as it enables the network to remain fully functional for the maximum time. We demonstrate that in a single hop, single channel network of n randomly distributed sensors, selection can be performed in O(n) time and O(n) energy, with no sensor being awake for more than O(1) time steps. We extend our results for a p-channel network, where p≤n1-ε and 0<ε≤1. We show that selection can be performed in time O(n/p) and energy O(n) with no sensor being awake for more than O(1) time steps. View full abstract»

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  • Providing application QoS through intelligent sensor management

    Page(s): 93 - 101
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    Wireless sensor networks are uniquely characterized by tight energy and bandwidth constraints. These networks should be designed to provide enough data to their application so that a reliable description of the environment can be derived, while operating as energy-efficiently as possible and at the same time meeting bandwidth constraints. These goals are typically contradicting and must be balanced at the point where the application is best satisfied. In this paper, we address the problem of maximizing lifetime for a wireless sensor network while meeting a minimum level of reliability. This maximization is achieved by jointly scheduling active sensor sets and finding paths for data routing. Simulation results show that network lifetime can be significantly increased through such methods. View full abstract»

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