Introduction to Wireless Sensor Networks

What are sensor networks?

Sensor networks consist of many - up to several thousand - small distributed computing devices that sense and interact with the environment. Various sensors allow a sensor node to measure
temperature, sound, vibration, pressure, motion or pollution. Their low price and low energy
ensures that sensor networks can be deployed in large numbers. A sensor node consists of a smal
microcontroller, a radio device, some sensors, and a power supply, usually a battery. Their resources in terms of energy, memory, computational power and bandwidth are severely limited, making sensor nodes an interesting research topic. Due to their processing and communication abilities sensor networks are intelligent. Thus, the network can independently from human interaction deal with node failure, aggregate measurements from various nodes into meaningful data, reprogram selected nodes for new tasks

Why are sensor networks cool?

In the 1980s, the PC revolution put computing at our fingertips.
In the 1990s, the Internet revolution connected us to an information web that spans the planet.
And now the next revolution is connecting the Internet back to the physical world we live in-in
effect, giving that world its first electronic nervous system.
Call it the Sensor Revolution: an outpouring of devices that monitor our surroundings in ways we
could barely imagine a few years ago. Some of it is already here. The rest is coming soon

What are the real time applications?

WSN applications can be classified into two categories. monitoring and tracking. Monitoring applications include indoor/outdoor environmental monitoring, health and wellness monitoring, power monitoring, inventory location monitoring, factory and process automation, and seismic and structural monitoring. Tracking applications include tracking objects, animals, humans, and vehicles.

• PinPtr ( Shooter location tracking)
  
• DeerNet (Deer monitoring)
  
• CenWits (Rescue system)
  
• BabyGlove ( Infant monitoring)
  
• iMouse (Fire survilliance)
  
• FireLine (Monitor FireFighter Health)
  
• SEAMONSTER ( Setup for Glacier monitoring )
  
• QCAT(Cattle monitoring)

Road tunnel fire rescue with wireless sensor networks ( from Discovery)

There is more to go. Currently it's hardly 8-10 year old technology. The researchers are facing challenges in

• Limited power
• Ad-Hoc operation ( there is no centralized control over network )
• Diversity in applications
• Limited radio communication and computation capabilities

Quick Links and References

Crossbow blog for interesting applications currently deployed
National Science Foundation :WSN Page
Wireless sensor network survey : Jennifer Yick, Biswanath Mukherjee, Dipak Ghosal(Article in press) ScienceDirect 2008