Wireless Sensor Networks

Nuwan GajaweeraResearch Engineer

Outline

• Motes & Wireless Sensor Networks• WSN Applications • TinyOS• WSN research at the Dialog Lab

Motes & Wireless Sensor Networks

Mote

• A very low cost low power computer• Monitors one or more sensors• A Radio Link to the outside world• Are the building blocks of Wireless Sensor

Networks (WSN)

External Memory

Dig

ital I

/O p

orts

Radio Transceiver

Ana

log

I/O P

orts

Microcontroller

A/D

D/A

Sensor

Sensor

Wireless Sensor Network

“A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using

sensors to cooperatively monitor physical or environmental conditions, such as

temperature, sound, vibration, pressure, motion or pollutants, at different locations.”

- Wikipedia

Wireless Sensor Networks

• Formed by hundreds or thousands of motes that communicate with each other and pass data along from one to another

• Research done in this area focus mostly on energy aware computing and distributed computing

Super Node

Links to Other networks or Similar Super Nodes

Motes

WSN Applications• Environmental/Habitat monitoring • Acoustic detection • Seismic Detection • Military surveillance • Inventory tracking • Medical monitoring • Smart spaces • Process Monitoring

Habitat Monitoring on Great Duck Island

• http://www.greatduckisland.net/

• Intel Research Laboratory at Berkeley initiated a collaboration with the College of the Atlantic in Bar Harbor and the University of California at Berkeley to deploy wireless sensor networks on Great Duck Island, Maine (in 2002)

• Monitor the microclimates in and around nesting burrows used by the Leach's Storm Petrel

• Goal : habitat monitoring kit for researchers worldwide

FireBug

• Wildfire Instrumentation System Using Networked Sensors• Allows predictive analysis of evolving fire behavior• Firebugs: GPS-enabled, wireless thermal sensor motes

based on TinyOS that self-organize into networks for collecting real time data in wild fire environments

• Software architecture: Several interacting layers (Sensors, Processing of sensor data, Command center)

• A project by University of California, Berkeley CA.

Preventive Maintenance on an Oil Tanker in the North Sea: The BP Experiment

• Collaboration of Intel & BP

• Use of sensor networks to support preventive maintenance on board an oil tanker in the North Sea.

• A sensor network deployment onboard the ship

• System gathered data reliably and recovered from errors when they occurred.

• The project was recognized by InfoWorld as one of the top 100 IT projects in 2004,

• Basically a location-aware mote. • Includes an Ultrasound transmitter and receiver.• Uses the combination of RF and Ultrasound technologies

to establish differential time of arrival and hence linear range estimates

• Based on Cricket Indoor Location System developed by a MIT researcher Nissanka Bodhi Priyantha

“Cricket” Mote

TinyOS• What is TinyOS

– open-source operating system– wireless embedded sensor networks– component-based architecture

• Developed at UCB in collaboration with Intel Research• Current Stable Version is 1.1.15• TinyOS 2.0 (T2) released on 6/11• Main Ideas –

– Low complexity– Conserve power – sleep as frequently as possible

• Written in nesC – next generation C compiler

Different Targets

mica mica2 mica2dot micaz

telos telosb rene2 pc

Mica2

• Extremely popular mote• 8-bit AVR Controller• FSK radio• Data-logger flash

Our contributions to the WSN world

Mica2 Clone

Data Mule

• DataMule – a mobile entity present in the environment that will pick up data from the mote when in range, buffer it, and drop off the data at base station– ex: People, Vehicles, Livestock

Data Mule

Data Mule

Base Station

Leaf Node

Data Mule

Data Mule

Base Station

Data Mule - Applications

• Collecting a data in a sparse sensor network

• Tracking movement of mobile elements– Vehicles– Livestock– Wild Animals

Data Mule

Base Station

Data Mule - Research undertaken

• Development of a TDMA/CSMA hybrid MAC– TinyOS currently has a CSMA MAC– Hope to improve throughput by employing TDMA– Time is divided into transmission periods and contention periods– Nodes will contend with each other to join “the transmission

group” during the contention period.– Nodes in the transmission group will be allocated a time-slot in

the transmission period.• Development of data storage engine optimized for fast

retrieval

Thank you..