Wireless sensor network

Overview

A wireless sensor network (WSN) is a network made of many small computers, which are employed in the processing of sensor data. These small computers are extremely basic in terms of their interfaces and their components. They usually only consist of sensors (including specific conditioning circuitry), a communication device (radio transceivers), and a power supply. Other possible inclusions are energy harvesting modules, secondary ASICs, and possibly secondary communication devices (RS232, USB...).

Uses for WSNs

The uses for WSNs are many and varied. They could be used in industry to monitor dangerous/hermitically-sealed environments. They could be deployed in wilderness areas, where they would remain for many years (monitoring some environmental variable) without the need to recharge/replace their power supplies. They could form a perimeter about a property and monitor the progression of intruders (using advanced application transfer techniques?). There are simply a near infinite amount of uses for WSNs!

Challenges

There are many challenges in implementing a WSN ranging from hardware, software, mechanical and even human-related. Keeping the power usage sufficiently low so that they operate for enough time involves careful power management and in some cases managing charging. Radio communication hardware has to be small enough while using a suitable network algorithm. A high bit-rate saves power by reducing communication time but in order to obtain a good range, especially in wet environments high-power hardware is often needed. These two tasks illustrate the careful balance and compromises that are needed in WSN designs.

There are four major challenges associated with Sensor networks: 1. Power consumption 2. Lifetime 3. Communication 4. Size

WSN nodes need to be "smart" enough to operate autonomously if they are disconnected from their network, cooperate with each other to form a new network if necessary and manage their data capture/power to provide the best data possible.

Visualization of Wireless Sensor Networks Data

The data gathered from wireless sensor networks is usually saved in the form of numerical data in a central base station. There are many programs, like TosGUI and MonSense, that facilitate the viewing of these large amounts of data. Additionally, the Open Geospatial Consortium (OGC) is specifying standards for interoperability interfaces and metadata encodings that enable real time integration of heterogeneous sensor webs into the Internet, allowing any individual to monitor or control Wireless Sensor Networks through a Web Browser.

WSN Research Centers

Examples of major academic centers for research in wireless sensor networks are CITRIS at Berkeley and CENS at UCLA, in the USA and the NCCR MICS at EPFL, in Switzerland.

Center for Embedded Networked Sensing (CENS)

The Center for Embedded Networked Systems (CENS) at the University of California, Los Angeles, directed by Deborah Estrin, is also a leading research center with $40 million in core funding from the National Science Foundation [1].

Center for Information Technology Research in the Interest of Society (CITRIS)

The Center for Information Technology Research (CITRIS) in the Interest of Society at the University of California, Berkeley, currently directed by S. Shankar Sastry, is a $300 million multicampus research center that includes research and development of wireless sensor networks, and has used them to study microclimate variations in individual redwood trees [2].

National Center of Competence in Research on Mobile Information and Communication Systems (NCCR MICS)

The NCCR MICS was launched in 2001 at EPFL. It is performing research in mobile information and communication systems, with a strong emphasis on wireless sensor networks and novel self-organizing networks and information systems.

External link

Overview of wireless sensor networks from the IEEE Computer Society.
EnOcean EnOcean enables a wireless community of batteryless sensors to connect to a just a few transceivers that need to be powered for continuous operation.
Software Infrastructure for Wireless Sensor Networks.

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