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Reconfigurable Sensor Networks
Chris ElliottHonours in Digital Systems
Charles Greif and Nandita Bhattacharjee
Chris Elliott 2
Reconfigurable Sensor Networks
• Aim of Project– Demonstrate a sensor network that reconfigures
• Via network and sensors
• Overview– Background– Hardware– Wireless Communication– TinyOS– How it will be done– Relevance of the research
Chris Elliott 3
Background
• Smart Dust Project– Hill, Hollar, Culler, Pister and Katz at the University of California in Berkeley
• Funded by Intel and Department of Defense
• Research started in 1995
– Using the idea of processing, sensing, communications and power in one chip
– Sensor Node also named Mote by people at Berkeley
– Tiny Operating System
• Current research concentrating on size
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Experiments
• Wireless sensor networks have been used– Great Duck Island Habitat Monitoring
• Looked at habitat on this island– url: www.greatduckisland.net
– COTS BOTS• Motes were connected to mobile robots
– url: www.eecs.berkeley.edu/~sbergbre/CotsBots/cotsbots.html
– Palms Fixed Mobile Experiment• Tracking vehicles on a road
– url: robotics.eecs.berkeley.edu/~pister/20Palms0103/
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Hardware• Processor
– Atmel ATmega 128L
– Low Power – 2.7V
– RISC
– A/D converter
•Memory– 128Kb program
– 512Kb data
•Radio– 868/916Mhz
– 150m range
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Wireless Communication
• Ad-hoc scheme– No organised connectivity
before deployment– Still meets needs of application
• Broadcasting– Motes find out who neighbours
are to discover topology– Periodic checks are performed
• Multi-hop route– Allows for easy reconfiguration
of network
• Flooding– Basestation mote sends
information to network
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TinyOS
• Developed to act as a generic environment• Event based• Uses a set of Components
– Commands– Events– Fixed frame size– Tasks
• Task Scheduler– FIFO– Switches processor between sleep and active mode
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TinyOS
• Set of commands – Requests made to lower level
components
• Event Handlers– Events received from lower
level components– At lowest level triggers
processor to wake up
• Commands used• Events signaled
– Passed to higher level components
• Operate on its state
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Research
• This will be done by:– Developing system architecture
• Using 3 motes, one as a basestation
– Developing code to implement reconfiguration • Using C code and TinyOS C compiler
• Using debugger and simulator that comes with TinyOS