Work in Progress for Wireless Sensor Networks

1
Work in Progress for Wireless Sensor Networks

• Yonghe Liu
• yonghe_at_cse.uta.edu
• Dept. of Computer Science and Engineering
• The University of Texas at Arlington

Partially supported by NSF CNS-0721951, NSF IIP
0712433, and Texas ARP
2
Current efforts

• Develop sensor networks that are
• Energy efficient multiple years operation
• Easy to use as web applications to users
• Easy to program -- drag and drop
• Easy to clean up physically no one left behind

3
An easier route

• Focus on applications that are less demanding
• Temperature, humidity, light sensing, etc.
• Low data rate at several bytes/node/minute often
  sufficient

• Typical hardware platform TelosB
• 250Kbps bandwidth (Zigbee)
• 8MHz Microcontroller
• 10KB ram
• 1MB flash
• And an extensive set of overlaying solutions

Over Kill
4
Hardware

• Pseudo-RFID module on board
• Use RFID writing
• No backscattering though
• Semi-passive for long range
• Enable asynchronous communication among nodes
• Transmitter directly excites and writes into
  receiver memory
• Always ON receiver
• Transmit whenever desired
• No periodic wakeup/sleep, simplified MAC
  operation

5
Network asynchronous communication pattern

• Overall a store and forward, asynchronous
  communication architecture

• Benefit
• Utilize the whole time line
• Transmission anytime, not in a time window
• No-need of CSMA/CD MAC
• Low rate of data
• Avoid heavy collisions
• Avoid idle listening
• No wakeup synchronization overhead

Energy Efficiency
6
Cleaning up

• If backscattering enabled,
• True RFID capability
• Locating and identifying node corpses

7
Onboard software

• Simplified to be necessary
• Using standard Zigbee stack if possible
• Quite powerful
• Open source

8
PC/Sink software

• Simplified but limited programming
• Drag and drop
• Like labview
• Web based visual/management tools

9
Advanced topics due to asynchronism

• Signal processing
• Delay reduction
• Joint synchronous and asynchronous design