Showing papers on "Wireless sensor network published in 1999"

Next century challenges: scalable coordination in sensor networks

Abstract: Networked sensors-those that coordinate amongst themselves to achieve a larger sensing task-will revolutionize information gathering and processing both in urban environments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured differently from traditional network applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor network coordination. In this paper, we describe localized algorithms, and then discuss directed diffusion, a simple communication model for describing localized algorithms.

Adaptive protocols for information dissemination in wireless sensor networks

Abstract: In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminates information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of two specific SPIN protocols, comparing them to other possible approaches and a theoretically optimal protocol. We find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches. We also find that, in terms of dissemination rate and energy usage, the SPlN protocols perform close to the theoretical optimum.

On-demand multipath routing for mobile ad hoc networks

Abstract: Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently attracted attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called dynamic source routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Results show that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long path lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths.

Quality-of-service in ad hoc carrier sense multiple access wireless networks

Abstract: Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes.

Design considerations for distributed microsensor systems

Abstract: Wireless distributed microsensor systems will enable the reliable monitoring and control of a variety of applications that range from medical and home security to machine diagnosis, chemical/biological detection and other military applications. The sensors have to be designed in a highly integrated fashion, optimizing across all levels of system abstraction, with the goal of minimizing energy dissipation. This paper addresses some of the key design considerations for future microsensor systems including the network protocols required for collaborative sensing and information distribution, system partitioning considering computation and communication costs, low energy electronics, power system design and energy harvesting techniques.

Self-organizing distributed sensor networks

Abstract: Advances in CMOS IC and micro electrical-mechanical systems (MEMS) technologies are enabling construction of low-cost building blocks each of which incorporates sensing, signal processing, and wireless communications. Collections of these integrated microsensor nodes may be formed into sensor networks in a wide variety of ways, with characteristics that depend on the specific application--the total number of nodes, the spatial density, the geometric configuration (e.g., linear vs. areal), topographic aspects (e.g., smooth vs. rough terrain), and proximity and proportion of user/sink points. The power of these distributed sensor networks will be unleashed by means of their ability to self-organize, i.e., to bootstrap and dynamically maintain organizational structure befitting the purpose and situation that is presented, without the need for human assistance. A prototype sensor system and networking protocols are being developed under the DARPA/TTO AWAIRS Program and are described.

Performance of a novel self-organization protocol for wireless ad-hoc sensor networks

Abstract: The paper presents an ad-hoc architecture for wireless sensor networks and other wireless systems similar to them. In this class of wireless system the physical resource at premium is energy. Bandwidth available to the system is in excess of system requirements. The approach to solve the problem of ad-hoc network formation here is to use available bandwidth in order to save energy. The method introduced solves the problem of connecting an ad-hoc network. This algorithm gives procedures for the joint formation of a time schedule (similar to a TDMA schedule) and activation of links therein for random network topologies. This self-organization method is energy-sensitive, distributed, scalable, and able to form a connected network rapidly.

Energy-scalable protocols for battery-operated microsensor networks

Abstract: To maximize battery lifetimes of distributed wireless sensors, network protocols and data fusion algorithms should be designed with low power techniques. Network protocols minimize energy by using localized communication and control and by exploiting computation/communication tradeoffs. In addition, data fusion algorithms such as beamforming aggregate data from multiple sources to reduce data redundancy and enhance signal-to-noise ratios, thus further reducing the required communications. We have developed a sensor network system that uses a localized clustering protocol and beamforming data fusion to enable energy-efficient collaboration. We have implemented two beamforming algorithms, the Maximum Power and the Least Mean Squares (LMS) beamforming algorithms, on the StrongARM (SA-1100) processor. Results from our experiments show that the LMS algorithm requires less than one-fifth the energy required by the Maximum Power beamforming algorithm with only a 3 dB loss in performance. The energy requirements of the LMS algorithm was further reduced through the use of variable-length filters, a variable voltage supply, and variable adaptation time.

Development platform for self-organizing wireless sensor networks

Abstract: Distributed microsensor networks, built from collections of nodes each having the ability to sensor their environment, process the raw sensor data in cooperation with other neighboring nodes into information and then communicate that information to end users. These systems are designed to be self-organizing in the sense of establishing and maintaining their own network without the need for specialistic operators. In most envisioned applications, wireless communications are the most practical means of interconnection, eliminating the internode cabling. Long periods of autonomous operations in remote environments will need battery or other renewable energy sources. In order to prolong battery life, all node hardware and software functions need to be designed to consume minimal power. In general, a node will expend energy on local processing of sensor data to produce compressed information in order to reduce communications. These network systems are intended to support large numbers of such nodes to cover large geographic areas.

Scalable Coordination in Sensor Networks

Abstract: Network sensors those that coordinate amongst themselves to achieve a larger sensing task will revolutionize information gathering and processing both in urban environments and in inhospitable terrain. The sheer numbers of these sensors and the expected dynamics in these environments present unique challenges in the design of unattended autonomous sensor networks. These challenges lead us to hypothesize that sensor network coordination applications may need to be structured di erently from traditional network applications. In particular, we believe that localized algorithms (in which simple local node behavior achieves a desired global objective) may be necessary for sensor network coordination. In this paper, we describe localized algorithms, and then discuss directed di usion, a simple communication model for describing localized algorithms.

Wireless integrated network sensors (WINS)

Abstract: Wireless Integrated Network Systems (WINS) provide distributed network and Internet access to sensors, controls, and processors that are deeply embedded in equipment, facilities, and the environment The WINS network is a new monitoring and control capability for applications in transportation, manufacturing, health care, environmental monitoring, and safety and security WINS combine microsensor technology, low power signal processing, low power computation, and low power, low cost wireless networking capability in a compact system WINS networks will provide sensing, local control, and embedded intelligent systems in structures, materials, and environments This paper describes the WINS architecture and WINS technology components including sensor interface and WINS event recognition systems© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Design and upgrade of nonredundant and redundant linear sensor networks

Abstract: The design of sensor networks featuring minimum cost, while satisfying constraints of redundancy only, is examined. For this purpose, the concept of degree of redundancy for measurements and degree of observability for unmeasured variables are merged into one single property, the degree of estimability of a variable. In addition, the concept of estimation efficiency is introduced. Based on these concepts, mathematical programming procedures are presented that allow the design of sensor networks for different degrees of estimability of key variables.

Wireless Sensor Networks for Area Monitoring and Integrated Vehicle Health Management Applications

Abstract: components on a single die that will be produced in high volumes for low-cost. This will permit large numbers of Distributed, wireless, microsensor networks promise to wireless integrated networked sensors to be easily and enable a myriad of applications for sensing and controlling rapidly deployed. (e.g., airdropped into battlefields or the physical world. Rockwell Science Center has created a deployed throughout an aircraft or space vehicle) to form development environment for wireless integrated networked highly redundant, self-configuring, ad hoc sensor networks. sensors (WINS) that includes customizable, sensor-laden For ease of deployment, the nodes use wireless networked nodes and both mobile and inter-net-hosted user communications and are capable of establishing and interfaces. The WINS development system allows operating their own network. To prolong battery life, all node and network. functions are designed to consume examination of issues relative to design, deployment and usage of microsensor networks. WINS nodes sense their minimal power. Highly capable and ultra-reliable systems environment via multiple sensors, process sensor data both will be built out of large numbers of such nodes that are autonomously and in cooperation with neighboring nodes individually inexpensive and use cooperation between nodes into information, and communicate this information to users to produce highly reliable, high quality information. A via a variety of network topologies. WINS are self- summary of the technologies comprising the WINS systems ~organizing in that they establish and maintain the network is shown in Fig. 1. Rockwell's experience with prototype without user intervention. Minimizing power consumption wireless sensor networks points to the great ~potential for is a primary driver in WINS development. Each node robust, large-scale environmental and systems monitoring processes sensor data into information, thereby reducing and control. power-hungry communications requirements. Power minimization also drives the design of integrated WINS The Rockwell Science Center, in collaboration with hardware and the creation of new networking protocols researchers at UCLA, has developed a prototype specific to the needs of microsensor networks. Prototype development platform for experimenting with microsensor WINS are being applied to area monitoring, surveillance, networks under a number of government and industry and physical security, to networking of personnel and sponsored programs. The prototype node, called "WINS l", physical assets over large areas, as well as to machinery and is based on an open, modular design using widely available platform health and status monitoring. The WINS commercial-off-the-shelf (COTS) technology. To date more development environment and several of these applications than one hundred units of the latest version of wireless are discussed here.

Model-based diagnosis and control reconfiguration for discrete event systems: an integrated approach

Abstract: We describe an approach to automate the dynamic computation of optimal control/reconfiguration actions that can achieve pre-specified control objectives. This approach, based on model-based diagnostic representations and algorithms, integrates diagnostics and control reconfiguration for discrete event systems using a single modeling mechanism and suite of algorithms. When the system functionality degrades (i.e., failures occur in the systems), the diagnostic algorithm will isolate the most likely failures, and then the control mechanism will generate the least-cost actions that attempt to recover from the failure and maintain the control objectives. Results about the quality of the control actions generated and the complexity of computing these actions ate also presented. We illustrate our approach using a simple wireless sensor network.

Intelligent nodes for distributed sensor network

Abstract: Neural networks models and their training algorithms on a central computer with reference to a previously developed distributed sensor network are considered. The requirements for its intelligent node are formulated. Also the node's structure is offered which realises such intelligent functions, as sensor and other measuring channel components drift prediction using remote reprogramming.

An adaptive sensor network system for complex environments

Abstract: This paper describes the design and implementation of a sensor network system that can adapt to node failures and changes in node positions. The objective of this system is to support human actions in typical living and working environments such as buildings, offices, and homes. The adaptive sensor network system we designed and implemented can estimate the spatial position of each node, can detect a connection or disconnection between a node and the network, and can translate a position-based address into the appropriate set of sensor nodes. The evaluation results show the possibility of the system adapting to dynamic network changes.

On the impact of burst errors on wireless ATM

Abstract: There has been an emerging interest in using ATM for wireless transmissions. Because ATM is primarily designed for an essentially error-free environment, in the wireless context the sources of errors and their consequences must be thoroughly understood. While this concern is valid in any network, it takes on a new, more central role in the wireless environment, where error bursts as expected to be a very significant source of degradation. In this article we examine the impact of burst errors on the direct transfer of ATM cells over a wireless channel, taking into account the cell framing format as well as the cell delineation and synchronization mechanism. We also investigate the consequences of interleaving. We find that fragmenting the data in cells could result in a much higher error rate as seen by the higher layers relative to the bit error rate on the raw channel. We assess the adequacy of HEC-based cell delineation and deduce the most appropriate values of the parameters of the cell delineation algorithm for the wireless channel.

Battery-powered, wireless MEMS sensors for high-sensitivity chemical and biological sensing

Abstract: Researchers at Oak Ridge National Laboratory (ORNL) are developing selectively coated cantilever arrays in a surface-micromachined MEMS process for very high sensitivities in chemical and biological sensing. Toward this end, we have developed a one-dimensional (1-D) 10-element microcantilever array that we have coated with gold for mercury sensing and palladium for hydrogen sensing. Ultimately we will coat each element with a different coating. Currently, measurements have been performed using a companion analog 1.2-/spl mu/m CMOS eight channel readout chip also designed at ORNL specifically for the microcantilever arrays. In addition, we have combined our sensors with an ORNL-developed RF-telemetry chip having on-chip spread spectrum encoding and modulation circuitry to improve the robustness and security of sensor data in typical interference- and multipath-impaired environments. We have also provided for a selection of distinct spreading codes to serve groups of sensors in a common environment by the application of code-division multiple-access techniques. Our initial system is configured for use in the 915-MHz Industrial, Scientific, and Medical (ISM) band. The entire package is powered by four AA batteries.

Charge balance network with floating ground capacitive sensing

Abstract: A capacitance measurement system (100) amenable to implementation on an integrated circuit includes a switching network (102), a voltage driving element (104), a sensor network (106), and a feedback network (108). The sensor network (106) includes a fixed capacitor connected in series to a variable sensing capacitor. The feedback network (108) receives the voltage generated at the junction node between the two capacitors, and the other side of the sensor capacitor is connected to system ground. The voltage driving element (104), responsive to a signal from the switching network (102), shifts the local voltage which supplies power to the feedback network (108). The feedback network (108) generates a feedback signal representative of the difference in the charge stored on the series capacitors from a predetermined value. The switching network (102) includes a control which is operative to cyclically interconnect the feedback signal and reference potentials with the sensor network (106) and the voltage driving element (104), whereby the average change in the charge stored on the capacitors over each cycle is substantially equal to the predetermined value. In this configuration, the feedback signal is a predetermined function of a capacitance of the sensing capacitor.

A network architecture for global wireless position location services

Abstract: Major R&D activities are underway following the FCC rulings for the Wireless E-911 service. The goal is to determine the location of an emergency caller accurately, thus enhancing significantly the security of subscribers. Additional new applications include highway navigation and location sensitive billing, among others. Much of the research is focused on attaining a balance between location accuracy on one hand, and the cost on the other. We present an architecture for an efficient and cost effective wireless position location system using differential GPS with the GPRS of the GSM as the basic wireless infrastructure.

Self-organizing cooperative sensor network for remote surveillance: current results

Abstract: The capabilities of unattended ground sensors (UGSs) have steadily improved and have been shown to be of value in various military missions. Today's UGS are multi-functional, integrated sensor platforms that can detect and locate a wide variety of ground-based and airborne targets. The rather large size (> 1 cubic foot) and relatively expensive cost of these integrated platforms are two main drawbacks for remote surveillance applications that support rapidly deployable, small unit operations. As an alternative, remote surveillance may be possible with smaller, less costly sensors that work cooperatively together as a network. The objective of this study was to develop algorithms that can optimally organized and adaptively control a network of UGSs in order to achieve a surveillance mission. In the present study, the sensor network, a random distribution of acoustic sensors over a surveillance area, is tasked to detect and track any targets entering into the surveillance area. In addition, the sensor network is required to maximize its tracking accuracy and minimize its power utilization.

Multiregime MEMS sensor networks for smart structures

Abstract: This paper discusses sensor IC design and packaging approaches, sensor networks architecture and communication protocols, as well as current and future applications of a series of transducers which we have developed in order to address several of the unmet needs of sensing and closed loop control of smart structures and organism-like machines of the future. In particular, the approach described therein has been used to design and manufacture sensors tailored for the measurement of strain, rotation, displacement, pressure, vibration, flow, multi-axis fluid shear, multi-axis strain, tough, multi-axis acceleration, and sound. This paper describes a suite of networkable sensors designed to monitor the internal state of the system, such as strain and joint angle, as well as that of the environment and contact interface with the system, such as pressure, shear stress and contact forces and moments.

Development of a Humanoid H4 with Soft and Distributed Tactile Sensor Skin

Abstract: A wheel type humanoid robot “H4” is developed as a platform for the research on vision-tactile-action coupling in intelligent behavior of robots. The H4 has the features as follows: 1) upper-body consists of 19DOF (3DOF waist, 6DOF arm, 4DOF head), light weight and enough space to attach skin, 2) multi-value tactile switch and matrix gel tactile sensor, two types soft and distributed sensor skin covers upperbody, 3) each tactile sensor module has microprocessor module which is connected via I2 C serial bus and make sensor network, 4) PC/AT compatible onboard computer which is controlled by RT-linux and connected to a network via radio ethernet, 5) 3D vision facility and 6) self-contained. This paper describe the design, implementation and experiment of H4, which is expected to be a common test-bed in experiment and discussion for tactile based aspects of intelligent robotics.

Isolation of wireless ad hoc medium access mechanisms under TCP

Abstract: Mobile computing will be much used in the future, as is evident by such initiatives as Bluetooth, Iceberg and HomeRF. However, for mobile computing to be successful, an obvious layer, the MAC layer, must be efficient in channel access and reservation. Therefore, in-depth understanding is needed of the wireless MAC layer if wireless computing is to takeoff. Many random access wireless MAC protocols have been proposed and standardized. However, there has not yet been an attempt to understand why certain designs are used and what makes certain protocols better than others. In this paper, we survey several popular, contemporary, wireless, random access MAC protocols and determine the effects behind the design choices on these protocols.

Self-organizing cooperative sensor network for remote surveillance

Abstract: The capabilities of unattended ground sensors (UBSs) have steadily improved and have been shown to be of value in various military missions. Today's UGS are multifunctional, integrated sensor platforms that can detect and locate a wide variety of ground-based and airborne targets. Due primarily to cost and size constraints of these UGS, they have not been widely used for law enforcement surveillance applications. As an alternative to a single, monolithic sensor platform, remote surveillance may be possible with smaller, less obtrusive sensors that work cooperatively together as a network. The objective of this study was to develop algorithms that can optimally organize and adaptively control a network of UGSs in order to achieve a surveillance mission. In the present study, the sensor network, a random distribution of sensors over a surveillance area (emulates airborne sensor deployment), determines an optimal combination of its sensors that will detect multiple targets and consume the lease amount of power. This problem is considered a multiobjective optimization problem to which there is no unique solution. Furthermore, for a linearly increasing number of sensors, the combinatorial search space increases exponentially. To reduce the search space, a novel clustering method was developed based on whether the sensor can sense the target rather than on similarities between the sensors. A genetic algorithm (GA) was used to obtain a quasioptimal solution for the sensor combination problem. To evaluate the effectiveness of the optimization, figures of merit were developed that are applicable to a sensor network tasked with a surveillance problem. Software-simulated data was used to test software implementation of the clustering, optimization and figure of merit functions. The clustering method reduced the search space by an average of ten orders of magnitude. For a sensor population of 100 sensors that was tasked to detect 24 targets, the GA was able to select optimal sets of sensors for detection and minimization of power consumption. The results demonstrate the feasibility of optimally configuring and controlling a network of sensors for remote surveillance applications.

State of the art in signal processing for wireless SAW sensing

Abstract: Wireless measurement systems with passive SAW sensors offer the new and exciting perspectives for remote monitoring of rotating parts, or in harsh environments. This paper concentrates on the signal processing required for those sensor systems with regard to the sensors, the system hardware and the radio transmission. Different directly effected delay lines, impedance loaded devices and resonators have been used as SAW sensors. Wideband time domain interrogation and narrowband frequency domain interrogation have been investigated theoretically and experimentally in combination with the radio channel and the evaluation method. We focus on the occurring errors and the origins of these effects. Actual estimations for the different errors are given. We achieved a resolution of 10/sup -5/ to 10/sup -6/. The measurement's bandwidth is up to 10 kHz for conventional sensors and up to a few hundreds of kHz for the new transponder type. A read out distance without averaging of several meters is achieved.

Bi-directional communication into the deep ocean based on OrbComm satellite transmission and acoustic underwater communication

Abstract: At the end of 1997 the DOMEST projects started. The aim was the development of a moored sensor network in the deep ocean near the Canary Islands. With the implementation of a bi-directional satellite link and underwater acoustic modems, a data-link from land into the deep sea should be established on a daily basis. With DOMEST, remotely controlled measurement of element and particle transport in the deep sea will be possible. Remote control includes access to a variety of data without recovering sensors from the deep ocean. Data access will be possible at any time via the Internet and satellite communication. Sampling intervals can be changed interactively from land, status data from the instruments can be checked and it is possible to download the data subsequently. These possibilities allows an advanced sampling and probing of parameters depending on various environmental parameters, such as satellite derived ocean colour or particle input during dust storms. Communication underwater is based on 4 independent acoustic modem clients, combined with different sensors. Bi-directional data transmission between these modems is possible up to 2,400 baud. Each sensor package and acoustic modem is controlled by an integrated digital controller, responsible for hand-shaking and data-management. At the sea surface, a permanent surface buoy is moored in 3,600 m water depth. Above water, the OrbComm based satellite network establishes data transport between the moored systems and the land based ground station in Italy. At the ground station, messages are routed via SMTP into the Internet. During a scientific cruise of RV METEOR in May 1999, the first close-loop test-with a data request from a ship via satellite into the deep sea and back via satellite to the ship-has been performed successfully, within less than 8 minutes. The final configuration of the complete DOMEST mooring will be deployed at 3,600 m water depth over a maximum duration of one year. New sensors will provide high-resolution data on particle fluxes and element concentrations in the deep ocean.