Showing papers on "Sensor web published in 2003"
11 Aug 2003
TL;DR: The history of research in sensor networks over the past three decades is traced, including two important programs of the Defense Advanced Research Projects Agency (DARPA) spanning this period: the Distributed Sensor Networks (DSN) and the Sensor Information Technology (SensIT) programs.
Abstract: Wireless microsensor networks have been identified as one of the most important technologies for the 21st century. This paper traces the history of research in sensor networks over the past three decades, including two important programs of the Defense Advanced Research Projects Agency (DARPA) spanning this period: the Distributed Sensor Networks (DSN) and the Sensor Information Technology (SensIT) programs. Technology trends that impact the development of sensor networks are reviewed, and new applications such as infrastructure security, habitat monitoring, and traffic control are presented. Technical challenges in sensor network development include network discovery, control and routing, collaborative signal and information processing, tasking and querying, and security. The paper concludes by presenting some recent research results in sensor network algorithms, including localized algorithms and directed diffusion, distributed tracking in wireless ad hoc networks, and distributed classification using local agents.
3,269 citations
19 Sep 2003
TL;DR: This paper presents polynomial-time algorithms, in terms of the number of sensors, that can be easily translated to distributed protocols, and forms a decision problem to determine whether every point in the service area of the sensor network is covered by at least k sensors.
Abstract: One fundamental issue in sensor networks is the coverage problem, which reflects how well a sensor network is monitored or tracked by sensors. In this paper, we formulate this problem as a decision problem, whose goal is to determine whether every point in the service area of the sensor network is covered by at least k sensors, where k is a predefined value. The sensing ranges of sensors can be unit disks or non-unit disks. We present polynomial-time algorithms, in terms of the number of sensors, that can be easily translated to distributed protocols. The result is a generalization of some earlier results where only k=1 is assumed. Applications of the result include: (i) positioning applications, (ii) situations which require stronger environmental monitoring capability, and (iii) scenarios which impose more stringent fault-tolerant capability.
1,211 citations
05 Nov 2003
TL;DR: This paper is the first on secure information aggregation in sensor networks that can handle a malicious aggregator and sensor nodes, and presents efficient protocols for secure computation of the median and the average of the measurements, for the estimation of the network size, and for finding the minimum and maximum sensor reading.
Abstract: Sensor networks promise viable solutions to many monitoring problems. However, the practical deployment of sensor networks faces many challenges imposed by real-world demands. Sensor nodes often have limited computation and communication resources and battery power. Moreover, in many applications sensors are deployed in open environments, and hence are vulnerable to physical attacks, potentially compromising the sensor's cryptographic keys.One of the basic and indispensable functionalities of sensor networks is the ability to answer queries over the data acquired by the sensors. The resource constraints and security issues make designing mechanisms for information aggregation in large sensor networks particularly challenging.In this paper, we propose a novel framework for secure information aggregation in large sensor networks. In our framework certain nodes in the sensor network, called aggregators, help aggregating information requested by a query, which substantially reduces the communication overhead. By constructing efficient random sampling mechanisms and interactive proofs, we enable the user to verify that the answer given by the aggregator is a good approximation of the true value even when the aggregator and a fraction of the sensor nodes are corrupted. In particular, we present efficient protocols for secure computation of the median and the average of the measurements, for the estimation of the network size, and for finding the minimum and maximum sensor reading. Our protocols require only sublinear communication between the aggregator and the user. To the best of our knowledge, this paper is the first on secure information aggregation in sensor networks that can handle a malicious aggregator and sensor nodes.
918 citations
TL;DR: A sensor network can provide access to information anytime, anywhere by collecting, processing, analyzing and disseminating data, and actively participates in creating a smart environment.
Abstract: Advances in hardware and wireless network technologies have created low-cost, low-power, multifunctional miniature sensor devices. These devices make up hundreds or thousands of ad hoc tiny sensor nodes spread across a geographical area. These sensor nodes collaborate among themselves to establish a sensing network. A sensor network can provide access to information anytime, anywhere by collecting, processing, analyzing and disseminating data. Thus, the network actively participates in creating a smart environment.
851 citations
TL;DR: An architecture and system are designed and built that enable easy deployment of wide-area sensing services and provide the missing software components for realizing a worldwide sensor Web.
Abstract: We discuss about the IrisNet (Internet-scale resource-intensive sensor network services) project at Intel Research, we design an architecture and build a system that enable easy deployment of such wide-area sensing services. We aim to provide the missing software components for realizing a worldwide sensor Web. Wide-area architectures for pervasive sensing enable a new generation of powerful distributed sensing services. A worldwide sensor Web, in which users can query, as a single unit, vast quantities of data from thousands or even millions of widely distributed, heterogeneous sensors. Internet-connected PCs that source sensor feeds and cooperate to answer users' queries will form the global sensor Web's backbone. Developers of wide-area sensing services (service authors) deploy the services on this distributed infrastructure.
493 citations
20 Mar 2003
TL;DR: This paper proposes an efficient mechanism to recover sensors from a failed cluster that avoids a full-scale re-clustering and does not require deployment of redundant gateways.
Abstract: During the past few years distributed wireless sensor networks have been the focus of considerable research for both military and civil applications. Sensors are generally constrained in on-board energy supply therefore efficient management of the network is crucial to extend the life of the system. Sensors' energy cannot support long haul communication to reach a remote command site, thus they require multi-tier architecture to forward data. An efficient way to enhance the lifetime of the system is to partition the network into distinct clusters with a high-energy node called a gateway as cluster-head. Failures are inevitable in sensor networks due to the inhospitable environment and unattended deployment. However, failures in higher level of hierarchy e.g. cluster-head cause more damage to the system because they also limit accessibility to the nodes that are under their supervision. In this paper we propose an efficient mechanism to recover sensors from a failed cluster. Our approach avoids a full-scale re-clustering and does not require deployment of redundant gateways.
459 citations
Proceedings Article•
01 Jan 2003
Abstract: Smart sensors are small wireless computing devices that sense information such as light and humidity at extremely high resolutions. A smart sensor query-processing architecture using database technology can facilitate deployment of sensor networks. Smart-sensor technology enables a broad range of ubiquitous computing applications. Their low cost, small size, and untethered nature lets them sense information at previously unobtainable resolutions. We discuss about query processing in sensor networks.
426 citations
05 May 2003
TL;DR: The framework, SensorWare, defines, creates, dynamically deploys, and supports lightweight and mobile control scripts that allow the computation, communication, and sensing resources at the sensor nodes to be efficiently harnessed in an application-specific fashion.
Abstract: Wireless ad hoc sensor networks have emerged as one of the key growth areas for wireless networking and computing technologies. So far these networks/systems have been designed with static and custom architectures for specific tasks, thus providing inflexible operation and interaction capabilities. Our vision is to create sensor networks that are open to multiple transient users with dynamic needs. Working towards this vision, we propose a framework to define and support lightweight and mobile control scripts that allow the computation, communication, and sensing resources at the sensor nodes to be efficiently harnessed in an application-specific fashion. The replication/migration of such scripts in several sensor nodes allows the dynamic deployment of distributed algorithms into the network. Our framework, SensorWare, defines, creates, dynamically deploys, and supports such scripts. Our implementation of SensorWare occupies less than 180Kbytes of code memory and thus easily fits into several sensor node platforms. Extensive delay measurements on our iPAQ-based prototype sensor node platform reveal the small overhead of SensorWare to the algorithms (less than 0.3msec in most high-level operations). In return the programmer of the sensor network receives compactness of code, abstraction services for all of the node's modules, and in-built multi-user support. SensorWare with its features apart from making dynamic programming possible it also makes it easy and efficient without restricting the expressiveness of the algorithms.
311 citations
Book•
17 Dec 2003
TL;DR: This paper presents a meta-modelling architecture for distributed wireless sensor networks that automates the very labor-intensive and therefore time-heavy and expensive process of laying out and configuring these networks.
Abstract: Preface About the Author 1. Networked Embedded Systems 2. Smart Sensor Networks 3. Power-Aware Wireless Sensor Networks 4. Routing in Wireless Sensor Networks 5. Distributed Sensor Networks 6. Clustering Techniques in Wireless Sensor Networks 7. Security Protocols for Wireless Sensor Networks 8. Operating Systems for Embedded Applications 9. Network Support for Embedded Applications 10. Applications of Wireless Sensor Networks References Index
286 citations
05 Nov 2003
TL;DR: This system demonstrates the use of in-network wavelet-based summarization and progressive aging of summaries in support of long-term querying in storage and communication-constrained networks.
Abstract: Wireless sensor networks enable dense sensing of the environment, offering unprecedented opportunities for observing the physical world. Centralized data collection and analysis adversely impact sensor node lifetime. Previous sensor network research has, therefore, focused on in network aggregation and query processing, but has done so for applications where the features of interest are known a priori. When features are not known a priori, as is the case with many scientific applications in dense sensor arrays, efficient support for multi-resolution storage and iterative, drill-down queries is essential.Our system demonstrates the use of in-network wavelet-based summarization and progressive aging of summaries in support of long-term querying in storage and communication-constrained networks. We evaluate the performance of our linux implementation and show that it achieves: (a) low communication overhead for multi-resolution summarization, (b) highly efficient drill-down search over such summaries, and (c) efficient use of network storage capacity through load-balancing and progressive aging of summaries.
217 citations
01 Jun 2003
TL;DR: This paper introduces a set of efficient protocols and algorithms, DAM, EBAM, and EMLAM, for constructing and maintaining sensor aggregates that collectively monitor target activity in the environment.
Abstract: The development of lightweight sensing andcommunication protocols is a key requirement for designing resource constrained sensor networks. This paper introduces a set of efficient protocols and algorithms, DAM, EBAM, and EMLAM, for constructing and maintaining sensor aggregates that collectively monitor target activity in the environment. A sensor aggregate comprises those nodes in a network that satisfy a grouping predicate for a collaborative processing task. The parameters of the predicate depend on the task and its resource requirements. Since the foremost purpose of a sensor network is to selectively gather information about the environment, the formation of appropriate sensor aggregates is crucial for optimally allocating resources to sensing and communication tasks.This paper makes minimal assumptions about node onboard processing and communication capabilities so as to allow possible implementations on resource-constrained hardware. Factors affecting protocol performance are discussed. The paper presents simulation results showing how the protocol performance varies as key network and task parameters are varied. It also provides probabilistic analyses of network behavior consistent with the simulation results. The protocols have been experimentally validated on a sensor network testbed comprising 25 Berkeley MICA sensor motes.
06 Jan 2003
TL;DR: A variety of regular deployment topologies are presented, including circular and star deployments as well as deployments in square, triangular, and hexagonal grids.
Abstract: Sensors can be paired with radio units and deployed to form a wireless ad-hoc sensor network. Actual deployments must consider the coverage that can be achieved with a given number of sensors: this coverage varies with the range of the radios and the maximum allowable distance between any point in the area and the nearest sensor. Deployments must also preserve connectivity in spite of possible failure or energy depletion in a subset of the units. This paper presents and analyzes a variety of regular deployment topologies, including circular and star deployments as well as deployments in square, triangular, and hexagonal grids.
TL;DR: This work has developed distributed algorithms for mobile-sensor networks to physically react to changes or events in their environment or in the network itself, and presents two classes of motion-control algorithms that let sensors converge on arbitrary event distributions.
Abstract: In many sensor networks, considerably more units are available than necessary for simple coverage of the space. Augmenting sensor networks with motion can exploit this surplus to enhance sensing while also improving the network's lifetime and reliability. Sensor mobility allows better coverage in areas where events occur frequently. Another use of mobility comes about if the specific area of interest (within a larger area) is unknown during deployment. We've developed distributed algorithms for mobile-sensor networks to physically react to changes or events in their environment or in the network itself. Distribution supports scalability and robustness during sensing and communication failures. We present two classes of motion-control algorithms that let sensors converge on arbitrary event distributions. These algorithms trade off the amount of required computation and memory with the accuracy of the sensor positions. We also present three algorithms that let sensor networks maintain coverage of their environment. These algorithms work alongside either type of motion-control algorithm such that the sensors can follow the control law unless they must stop to ensure coverage.
01 Jan 2003
TL;DR: The concepts and characteristics of the sensor networks and the data in the networks are introduced, and the issues of the Sensor Network, the data management and the advance of the research are presented.
Abstract: Sensor networks are integration of sensor techniques, nested computation techniques, distributed computation techniques and wireless communication techniques. They can be used for testing, sensing, collecting and processing information of monitored objects and transferring the processed information to users. Sensor network is a new research area of computer science and technology and has a wide application future. Both academia and industries are very interested in it. The concepts and characteristics of the sensor networks and the data in the networks are introduced, and the issues of the sensor networks and the data management of sensor networks are discussed. The advance of the research on sensor networks and the data management of sensor networks are also presented.
31 Oct 2003
TL;DR: This paper addresses the challenges associated with securing in-network processing within WSNs, and proposes a collection of mechanisms for delegating trust to aggregators that are not initially trusted by individual sensor nodes.
Abstract: The benefits of in-network processing for wireless sensor networks include improved scalability, prolonged lifetime, and increased versatility. This paper addresses the challenges associated with securing in-network processing within WSNs, and proposes a collection of mechanisms for delegating trust to aggregators that are not initially trusted by individual sensor nodes. Security mechanisms are proposed to address the downstream requirement that sensor nodes authenticate commands disseminated from parent aggregators. Conversely, security mechanisms are also proposed to address the upstream requirement that aggregators authenticate data produced by sensors before aggregating. Simulation results in ns2 of the proposed mechanisms for secure in-network processing are presented, as well as implementation on a mote testbed.
05 Nov 2003
TL;DR: It is shown that large networks of location-aware sensors can be made cooperatively self-configuring, that is, that each sensor can run an algorithm locally, interacting only with neighboring nodes, such that after a number of iterations all sensors will have reached a consensus about their coordinates in some coordinate system.
Abstract: Physical location is an important attribute of a sensor’s data stream in a large number of sensor network applications. In addition, geographic information, for instance in the form of node coordinates in some common coordinate system, is a useful primitive in routing protocols such as geographic routing, information dissemination protocols such as directed diffusion using location attributes, and sensor query processing systems. We present a method to facilitate large-scale deployment of location-aware sensor networks. We show that large networks of location-aware sensors can be made cooperatively self-configuring, that is, that each sensor can run an algorithm locally, interacting only with neighboring nodes, such that after a number of iterations all sensors will have reached a consensus about their coordinates in some coordinate system. By doing this in an automated manner, large-scale sensor networks can eliminate the cumbersome and unscalable process of manually configuring sensor nodes with their location. In non-urban outdoor settings, nodes may obtain location information using an existing infrastructure such as GPS. However, GPS receivers may be too expensive, too large, too power-intensive for the desired application, or simply unavailable. One solution to this problem is an alternative location infrastructure such as Cricket that works in places that GPS does not. Another solution to these problems is to equip sensors with hardware capable of estimating distances to nearby nodes, and to have the sensors themselves selfconfigure into a consistent coordinate system.
01 Jan 2003
TL;DR: A survey of recent work addressing network protocols, including routing and information dissemination algorithms, for wireless sensor networks is presented, evaluating them in terms of design goals, assumptions, operation models, energy models, and performance metrics.
Abstract: Recent advances in MEMS (micro-electromechanical systems), processor, radio, and memory technologies have dramatically enabled development of wireless sensor networks A sensor network is a large network of small sensor nodes, capable of sensing, communication, and computation It can be deployed to sense some physical phenomenon for a wide variety of applications During recent years, research in wireless sensor networks has become more and more active Network protocols developed for sensor networks are of great importance to meet specific design goals of sensor networks We present a survey of recent work addressing network protocols, including routing and information dissemination algorithms, for wireless sensor networks We evaluate them in terms of design goals, assumptions, operation models, energy models, and performance metrics
01 Jan 2003
TL;DR: A simple algorithm is developed that detects and tracks a moving target, and alerts sensor nodes along the projected path of the target and its projected course.
Abstract: Networks of small, densely distributed wireless sensor nodes are capable of solving a variety of collaborative problems such as monitoring and surveillance We develop a simple algorithm that detects and tracks a moving target, and alerts sensor nodes along the projected path of the target The algorithm involves only simple computation and localizes communication only to the nodes in the vicinity of the target and its projected course The algorithm is evaluated on a small-scale testbed of Berkeley motes using a light source as the moving target The performance results are presented emphasizing the accuracy of the technique, along with a discussion about our experience in using such a platform for target tracking experiments
19 May 2003
TL;DR: This paper proposes a protocol called SAFE (sinks accessing data from environments) which attempts to save energy through data dissemination path sharing among multiple data sinks, and simulation results show that the proposed protocol is energy-efficient as well as scalable to a large data sink population.
Abstract: In sensor networks, it is crucial to design and employ energy-efficient communication protocols, since nodes are battery-powered and thus their lifetimes are limited. This paper studies data dissemination in two-tiered networks comprised of stationary sensor nodes and mobile data users who request periodic sensor data updates. We propose a protocol called SAFE (sinks accessing data from environments) which attempts to save energy through data dissemination path sharing among multiple data sinks. Simulation results show that the proposed protocol is energy-efficient as well as scalable to a large data sink population.
19 Sep 2003
TL;DR: The hierarchical connected dominating set (CDS) construction algorithm is extended to develop the role-based hierarchical self organization algorithm for wireless sensor networks, which establishes a network-wide infrastructure consisting of a hierarchy of backbone nodes, and sensing zones that include sensor coordinators, and Sensing collaborators (or sensing zone members).
Abstract: Efficiently self organizing a network hierarchy with specific assignment of roles (or tasks) to sensors based on their physical wireless connectivity and sensing characteristics is an important and challenging problem. In this paper, we extend the hierarchical connected dominating set (CDS) construction algorithm, proposed by Jie Wu, to develop our role-based hierarchical self organization algorithm for wireless sensor networks. The resulting self organized sensor network establishes a network-wide infrastructure consisting of a hierarchy of backbone nodes, and sensing zones that include sensor coordinators, and sensing collaborators (or sensing zone members). Our paper identifies the need for organizing a sensor network according to the tasks appropriate for each sensor node based on their initial deployment in the network. Past research in group-based (or hierarchical) sensor networks have ignored the possibility of utilizing both the physical communication and sensing characteristics to assign roles to sensor nodes. We demonstrate the effectiveness of our design, which considers both, through simulations.
19 May 2003
TL;DR: This work proposes a Web Services approach for the design of sensor networks, in which sensor nodes are service providers and applications are clients of such services, to enable a flexible architecture where sensor networks data can be accessed by users spread all over the world.
Abstract: The current sensor networks are assumed to be designed for specific applications, having strongly coupled data communication protocols. The future sensor networks are envisioned as comprising heterogeneous devices assisting to a large range of applications. To achieve this goal, a new architecture approach is needed, having application specific features separated from the data communication protocol, while influencing its behavior. We propose a Web Services approach for the design of sensor networks, in which sensor nodes are service providers and applications are clients of such services. Our main goal is to enable a flexible architecture where sensor networks data can be accessed by users spread all over the world.
TL;DR: This paper presents the architecture of the sensor gateway for Web-based management and its implementation details, and assumes that wireless sensor networks have 3-level regional hierarchy, but the gateway is flexible enough to cooperate with other type sensor networks.
Abstract: Wireless sensor networks consisting of hundreds to thousands of nodes are expected to find increasing deployment in coming years, as they enable reliable monitoring and analysis of physical worlds. These networks have unique features that are very different from traditional networks, e.g., the large number of nodes, limitation in power. Due to these unique features of wireless sensor networks, their management including querying becomes a challenging problem. In general, it is widely accepted that Web-based management should be used for managing and querying sensor networks. In this paper, we present the architecture of the sensor gateway for Web-based management and its implementation details. We assume that wireless sensor networks have 3-level regional hierarchy, but our gateway is flexible enough to cooperate with other type sensor networks. In addition, to make our gateway process user's query dynamically without intervention of user, a back socket is opened using Java applet. For this purpose, Java script code is embedded in Web page to link Java applet code.
TL;DR: The paper surveys some standard models of self-stabilization and relates these models to a sensor network, finding challenges and opportunities for integrating self-Stabilization with sensor networks.
Abstract: The advent of large-scale sensor networks highlights problems of fault tolerance and scale in distributed system, motivating designs that autonomously recover from transient faults and spontaneous reconfiguration. Self-stabilization is an attractive approach for such problems, however the standard model of research for self-stabilizing algorithms does not suit ad hoc networks of wirelessly communicating sensor nodes. The paper surveys some standard models of self-stabilization and relates these models to a sensor network. Challenges and opportunities are for integrating self-stabilization with sensor networks are illustrated with examples.
01 Jan 2003
TL;DR: This paper addresses the fundamental issue of defining a standard set of services and interface primitives which should be made available to an application programmer independently on their implementation on any present and future sensor network platform.
Abstract: This paper addresses the fundamental issue of defining a standard set of services and interface primitives which should be made available to an application programmer independently on their implementation on any present and future sensor network platform. As the definition of sockets has made the use of communication services in the Internet independent of the underlying protocol stack, communication medium and even operating system, the application interface we propose identifies an abstraction that is offered to any sensor network application and supported by any sensor network platform. The distributed service platform we introduce builds on the query/command paradigm already used in several sensor network implementations and includes time synchronization, location and naming services that support the communication and coordination among application components.
11 May 2003
TL;DR: This paper addresses the problem of maximizing lifetime for a wireless sensor network while meeting a minimum level of reliability by jointly scheduling active sensor sets and finding paths for data routing and results show that network lifetime can be significantly increased through such methods.
Abstract: 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.
01 Dec 2003
TL;DR: This paper proposes to enhance the sensor network by deploying limited number of mobile "swarms", which have much higher capabilities than the sensor nodes in terms of both hardware functionalities and networking capabilities.
Abstract: Sensor networking technologies have developed very rapidly in the last ten years. In many situations, high quality multimedia streams may be required for providing detailed information of the hot spots in a large scale network. With the limited capabilities of sensor node and sensor network, it is very difficult to support multimedia streams in current sensor network structure. In this paper, we propose to enhance the sensor network by deploying limited number of mobile "swarms". The swarm nodes have much higher capabilities than the sensor nodes in terms of both hardware functionalities and networking capabilities. The mobile swarms can be directed to the hot spots in the sensor network to provide detailed information of the intended area. With the help of mobile swarms, high quality of multimedia streams can be supported in the large scale sensor network without too much cost. The wireless backbone network for connecting different swarms and the routing schemes for supporting such a unified architecture is also discussed and verified via simulations.
01 Jan 2003
TL;DR: The paper shows how each layer in the protocol stack of a sensor node can be implemented as a component and how ports and contracts enable different layers to interact with each other in the initiator-reactor mechanism that is a fundamental concept of J-Sim.
Abstract: Sensor networks have gained considerable importance and attention in the past few years. Hence, an inevitable need for developing simulation frameworks for sensor networks in existing network simulators arises. In this paper, we describe our work in incorporating wireless sensor networks simulation in J-Sim. We have built a simulation framework for sensor networks that builds upon the autonomous component architecture (ACA) and the extensible internetworking framework (INET) of J-Sim. The paper shows how each layer in the protocol stack of a sensor node can be implemented as a component and how ports and contracts enable different layers (components) to interact with each other in the initiator-reactor mechanism that is a fundamental concept of J-Sim.
08 Mar 2003
15 Apr 2003
TL;DR: An overview of this new and exciting field of wireless sensor networks is provided and a brief discussion on the factors pushing the recent flurry of sensor network related research and commercial undertakings is discussed.
Abstract: Sensor networks consist of a set of sensor nodes, each equipped with one or more sensors, communication subsystems, storage and processing resources, and in some cases actuators. The sensors in a node observe phenomena such as thermal, optic, acoustic, seismic, and acceleration events, while the processing and other components analyze the raw data and formulate answers to specific user requests. Recent advances in technology have paved the way for the design and implementation of new generations of sensor network nodes, packaged in very small and inexpensive form factors with sophisticated computation and wireless communication abilities. Although still at infancy, these new classes of sensor networks, generally referred to as wireless sensor networks (WSN), show great promise and potential with applications ranging in areas that have already been addressed, to domains never before imagined. In this article we provide an overview of this new and exciting field and a brief discussion on the factors pushing the recent flurry of sensor network related research and commercial undertakings. We also provide overview discussions on architectural design characteristics of such networks including physical components, software layers, and higher level services. At each step, we highlight special characteristics of WSNs and discuss why existing approaches and results from wireless communication networks are not necessarily suitable in WSN domains. We conclude by briefly summarizing the state of the art and the future research directions.
Keywords:
wireless;
ad-hoc;
multi-hop;
sensor networks;
location discovery;
sensor coverage;
localized algorithms
01 Jan 2003
TL;DR: In this paper, the authors developed a Sensor Web that can monitor microclimates over appropriate scales of time and distance, allowing a continuous virtual presence for instant recognition of favorable conditions.
Abstract: The most rigorous tests of the ability to detect extant life will occur where biotic activity is limited by severe environmental conditions Cryogenic environments are among the most severe-the energy and nutrients needed for biological activity are in short supply while the climate itself is actively destructive to biological mechanisms In such settings biological activity is often limited to brief flourishes, occurring only when and where conditions are at their most favorable The closer that typical regional conditions approach conditions that are actively hostile , the more widely distributed biological blooms will be in both time and space On a spatial dimension of a few meters or a time dimension of a few days, biological activity becomes much more difficult to detect One way to overcome this difficulty is to establish a Sensor Web that can monitor microclimates over appropriate scales of time and distance, allowing a continuous virtual presence for instant recognition of favorable conditions A more sophisticated Sensor Web, incorporating metabolic sensors, can effectively meet the challenge to be in "the right place in the right time" This is particularly of value in planetary surface missions, where limited mobility and mission timelines require extremely efficient sample and data acquisition Sensor Webs can be an effective way to fill the gap between broad scale orbital data collection and fine-scale surface lander science We are in the process of developing an intelligent, distributed and autonomous Sensor Web that will allow us to monitor microclimate under severe cryogenic conditions, approaching those extant on the surface of Mars Ultimately this Sensor Web will include the ability to detect and/or establish limits on extant microbiological activity through incorporation of novel metabolic gas sensors Here we report the results of our first deployment of a Sensor Web prototype in a previously unexplored high altitude East Antarctic Plateau "micro-oasis" at the MacAlpine Hills, Law Glacier, Antarctica