Sensor web is a type of
sensor network
Wireless sensor networks (WSNs) refer to networks of spatially dispersed and dedicated sensors that monitor and record the physical conditions of the environment and forward the collected data to a central location. WSNs can measure environmental c ...
that heavily utilizes the
World Wide Web
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.
Documents and downloadable media are made available to the network through web se ...
and is especially suited for
environmental monitoring
Environmental monitoring describes the processes and activities that need to take place to characterize and monitor the quality of the environment. Environmental monitoring is used in the preparation of environmental impact assessments, as well a ...
.
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OGC's ''
Sensor Web Enablement Sensor Web Enablement (SWE) is a suite of standards developed and maintained by Open Geospatial Consortium
The Open Geospatial Consortium (OGC), an international voluntary consensus standards organization for geospatial content and location-bas ...
'' (SWE) framework defines a suite of web service interfaces and communication protocols abstracting from the heterogeneity of sensor (network) communication.
Definition
The term "sensor web" was first used by Kevin Delin of NASA in 1997,
to describe a novel wireless sensor network architecture where the individual pieces could act and coordinate as a whole. In this sense, the term describes a specific type of
sensor network
Wireless sensor networks (WSNs) refer to networks of spatially dispersed and dedicated sensors that monitor and record the physical conditions of the environment and forward the collected data to a central location. WSNs can measure environmental c ...
: an amorphous network of spatially distributed
sensor
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
platforms (pods) that wirelessly communicate with each other. This amorphous architecture is unique since it is both synchronous and
router-free, making it distinct from the more typical
TCP/IP
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
-like network schemes. A pod as a physical platform for a sensor can be orbital or terrestrial, fixed or mobile and might even have real time accessibility via the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
. Pod-to-pod communication is both omni-directional and bi-directional where each pod sends out collected data to every other pod in the network. Hence, the architecture allows every pod to know what is going on with every other pod throughout the sensor web at each measurement cycle. The individual pods (nodes) were all hardware equivalent
and Delin's architecture did not require special gateways or routing to have each of the individual pieces communicate with one another or with an end user. Delin's definition of a sensor web was an ''autonomous, stand-alone, sensing entity – capable of interpreting and reacting to the data measured – that does not necessarily require the presence of the World Wide Web to function''.
As a result, on-the-fly data fusion, such as false-positive identification and plume tracking, can occur within the sensor web itself and the system subsequently reacts as a coordinated, collective whole to the incoming data stream. For example, instead of having uncoordinated smoke detectors, a sensor web can react as a single, spatially dispersed, fire locator.
The term "sensor web" has also morphed into sometimes being associated with an additional layer connecting sensors to the
World Wide Web
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.
Documents and downloadable media are made available to the network through web se ...
.
The Sensor Web Enablement (SWE) initiative of the
Open Geospatial Consortium
The Open Geospatial Consortium (OGC), an international voluntary consensus standards organization for geospatial content and location-based services, sensor web and Internet of Things, GIS data processing and data sharing. It originated in 1994 ...
(OGC) defines service interfaces which enable an interoperable usage of sensor resources by enabling their ''discovery'', ''access'', ''tasking'', as well as ''eventing and alerting''.
[
] By defining standardized service interfaces, a sensor web based on SWE services hides the heterogeneity of an underlying sensor network, its communication details and various hardware components, from the applications built on top of it.
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OGC's SWE initiative defines the term "sensor web" as ''an infrastructure enabling access to sensor networks and archived sensor data that can be discovered and accessed using standard protocols and application programming interfaces''. Through this abstraction from sensor details, their usage in applications is facilitated.
Characteristics of Delin's ''sensor web'' architecture
Delin designed a sensor web as a web of interconnected pods. All pods in a sensor web are equivalent in hardware (there are no special "gateway" or "slave" pods). Nevertheless, there are additional functions that pods can perform besides participating in the general sensor web function. Any pod of a sensor web can be a ''portal pod'' and provides users access to the sensor web (both input and output).
NASA Creates Thinking RF Sensors
Access can be provided by RF modem, cell phone connections, laptop connections, or even an Internet Server. In some cases, a pod will have an attached removable memory unit (such as a USB stick or a laptop) that stores collected data.
The term of ''mother pod'' refers to the pod that contains the master clock of the synchronous sensor web system. The mother pod has no special hardware associated with it, its designation as a mother is merely based on the ID number associated with the pod. Often the mother pod serves as a primary portal point to the Internet, but this is done only for deployment convenience. Early papers referenced the mother pod as "a prime node" if it additionally contained special hardware for a particular type of input/output device (say an RF modem).
Because of the inherent hopping of data within a sensor web, a pod with no attached sensors can be deployed as a ''relay'' with the single purpose of facilitating communication between the other pods and to expand the communication range to a particular end-point (such as a mother pod).
Sensors can be attached to relay pods at a later time and relays can also serve as portal pods.
Each pod usually contains:
* one or more sensor leading to one or more data channel,
* a processing unit such as a
micro-controller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable ...
or
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
,
* a two-way communication component such as a
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
and
antenna
Antenna ( antennas or antennae) may refer to:
Science and engineering
* Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves
* Antennae Galaxies, the name of two collid ...
(radio ranges are typically limited by government spectrum requirements; unlicensed bands will allow for communication of a few hundred yards in unobstructed areas, although line of sight is not a requirement),
* an energy source such as a battery coupled with a
solar cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. ,
* a package to protect components against sometimes harsh environment,
Each pod also typically requires a support such as a pole or tripod.
Sensor Web in Antarctica: Developing an intelligent, autonomous platform for locating biological flourishes in cryogenic environments
The number of pods may vary, with examples of sensor webs with 12 to 30 pods.
The shape of a sensor web may impact its usefulness, for instance a particular deployment
made sure each pod was in range to communicate with at least two other pods. Sensor web measurement cycles have typically been between 30 seconds and 15 minutes for deployed systems thus far.
Sensor webs consisting of pods have been deployed that have spanned miles and run continuously for years.
Sensor webs have been fielded in harsh environments (including deserts, mountain snowpacks, and Antarctica)
for the purposes of environmental science and have also proved valuable in urban
search and rescue
Search and rescue (SAR) is the search for and provision of aid to people who are in distress or imminent danger. The general field of search and rescue includes many specialty sub-fields, typically determined by the type of terrain the search ...
and infrastructure protection.
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The technology is not only monitoring the environment but sometimes also controlling the environment by actuating devices.
See also
*
Observations and Measurements Observations and Measurements (O&M) is an international standard which defines a conceptual schema encoding for observations, and for features involved in sampling when making observations. While the O&M standard was developed in the context of geog ...
*
Open Geospatial Consortium
The Open Geospatial Consortium (OGC), an international voluntary consensus standards organization for geospatial content and location-based services, sensor web and Internet of Things, GIS data processing and data sharing. It originated in 1994 ...
*
Semantic Sensor Web The Semantic Sensor Web (SSW) is a marriage of sensor web and semantic Web technologies. The encoding of sensor descriptions and sensor observation data with Semantic Web languages enables more expressive representation, advanced access, and formal ...
*
Sensor Grid
A sensor grid integrates wireless sensor networks with grid computing concepts to enable real-time data collection and the sharing of computational and storage resources for sensor data processing and management. It is an enabling technology for bu ...
: Sensor Web Meets Grid Computing
*
SensorML
SensorML is an approved Open Geospatial Consortium standar and an XML encoding for describing sensors and measurement processes. SensorML can be used to describe a wide range of sensors, including both dynamic and stationary platforms and both in- ...
References
Further reading
* ''Sensor Webs,'' K.A. Delin, S.P. Jackson, and R.R. Some NASA Tech Briefs 1999, 23, 9
Open access (publishing), open access publication.
* ''The Sensor Web: Distributed Sensing for Collective Action,'' Kevin A. Delin Sensors Online July 2006, 1
Open access (publishing), open access publication.
* ''The Sensor Web: A Distributed, Wireless Monitoring System,'' Kevin A. Delin Sensors Online April 2004, 2
Open access (publishing), open access publication.
* ''New Generation Sensor Web Enablement,'' Arne Bröring, Johannes Echterhoff, Simon Jirka, Ingo Simonis, Thomas Everding, Christoph Stasch, Steve Liang, Rob Lemmens Sensors 2011, Volume 11, Number 3, 2652-269
Open access (publishing), open access publication.
* ''Environmental Studies with the Sensor Web: Principles and Practice,'' Kevin A. Delin, Shannon P. Jackson, David W. Johnson, Scott C. Burleigh, Richard R.Woodrow, J. Michael McAuley, James M. Dohm, Felipe Ip, Ty P.A. Ferré, Dale F. Rucker, Victor R. Baker Sensors 2005, 5, 103-11
Open access (publishing), open access publication.
* ''OGC Sensor Web Enablement: Overview and High Level Architecture,'' Botts, Percivall, Reed, and Davidso
OGC White Paper, July 2006
Open access (publishing), open access publication.
* ''Open Sensor Web Architecture: Core Services,''Xingchen Chu, Tom Kobialka, Bohdan Durnota, and Rajkumar Buyya, Proceedings of the 4th International Conference on Intelligent Sensing and Information Processing (ICISIP 2006,IEEE Press, Piscataway, New Jersey, USA, , 98-103pp), Dec. 15-18, 2006, Bangalore, India
Open access (publishing), open access publication.
* ''A SensorWeb Middleware with Stateful Services for Heterogeneous Sensor Networks,''Tom Kobialka, Rajkumar Buyya, Christopher Leckie, and Rao Kotagiri, Proceedings of the 3rd International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP 2007, IEEE Press, Piscataway, New Jersey, USA), Dec. 3-6, 2007, Melbourne, Australia
Open access (publishing), open access publication.
External links
{{External links, date=March 2015
SensorWare Systems- The company spun out of NASA to commercialize the sensor web technology.
Sensor Web Alliance– An organization that is developing a collaborative research platform called the Sensor Web Alliance (SWA). The aim is to pool resources in the SWA, coordinate research and allow participating organisations to share IP, which will spread risk and lower the cost of entry.
SenseWeb Project– A Microsoft Research project that lets users visualize and query real-time data using a geographical interface such as Windows Live Local and allows data owners to easily publish their live data using a web service interface.
GeoSensor Web Lab, University of Calgary– A university research lab that is developing a GIS infrastructure for the Sensor Web and its applications. Several sensor web applications have been developed and deployed for environmental and agricultural applications. Project information, publications, and demo videos can be found on this site.
52°North– An open partnership organization that interoperable web services and data encoding models, which constitute the technical building blocks of Spatial Data Infrastructures (SDIs).
SWSL at the Institute for Geoinformatics (IFGI) of the University of Muenster– The Sensor web, Web-based geoprocessing, and Simulation Lab (SWSL) is a university lab working on the building blocks of the geosensor web to make all different kinds of sensors discoverable, accessible and taskable in an interoperable way.
OGC SWE– Since 2002, the Open Geospatial Consortium (OGC) has had a focused Sensor Web Enablement (SWE) activity. From the OGC perspective, a sensor web refers to web accessible sensor networks and archived sensor data that can be discovered and accessed using standard protocols and application program interfaces (APIs).
Open SensorWeb Architecture Project– The project focuses on the development of service-oriented middleware for SensorWeb that integrates sensor networks and distributed computing environments such as computational grids.
Sensorweb Research Laboratory– A research lab at Georgia State University, developing sensor web systems and applying them to scientific and social applications, such as environment monitoring, smart environments, and smart grid applications.
SEPS Project– The Self-adaptive Earth Predictive System (SEPS) concept combines Earth System Models (ESM) and Earth observations (EO) into one system through standard Web services. This is a collaborative project that consists of scientists from th
Center for Spatial Information Science and Systems (CSISS)of
George Mason University
George Mason University (George Mason, Mason, or GMU) is a public research university in Fairfax County, Virginia with an independent City of Fairfax, Virginia postal address in the Washington, D.C. Metropolitan Area. The university was origin ...
, NASA GSFC, and UMBC.
Networks
Geographic information systems
Sensors