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

Chris Elliott 4

Background

Chris Elliott 5

Background

Chris Elliott 6

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/

Chris Elliott 7

Hardware• Processor

– Atmel ATmega 128L

– Low Power – 2.7V

– RISC

– A/D converter

•Memory– 128Kb program

– 512Kb data

•Radio– 868/916Mhz

– 150m range

Chris Elliott 8

Hardware•Sensors

–Light

– Temp

– Acoustic

–Magnetic

– Acceleration

–Microphone

Chris Elliott 9

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

Chris Elliott 10

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

Chris Elliott 11

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

Chris Elliott 12

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

Chris Elliott 13

Conclusion

• Current Work• Topics Covered

– Hardware– TinyOS– Wireless Communication– Smart Dust– How the research will be undertaken

• Relevance of Research