Introduction to Theory and Applications of Self Organizing Wireless Sensor Networks Vijay K. Devabhaktuni & James W. Haslett Department of Electrical and Computer Engineering University of Calgary 13 July 2004

2 Agenda  Introduction  Self Organizing Wireless Sensor Networks  Experimental System  Wireless Sensor Networks in Patient Monitoring  Demonstration  Summary

3 Wireless Sensor Network (WSN) A wireless sensor network consists of a large number of nodes deployed in the environment being sensed and controlled through wireless communication. Typically, a WSN consists of A number of remote nodes (we refer to them as motes) Base station

4 Features: The remote nodes self- assemble into a network. The sensor information is propagated to the base station. Nodes collaborate i.e. intermediate nodes assist distant nodes to reach the base station. Routing Tree Link Connectivity Base Station Self Organizing WSN

5 Highlights Micro-sensors, on-board processing and wireless interface are all possible at very small scale! WSN are able to monitor a phenomena up-close Spatio-temporally dense environmental monitoring becomes a reality Networked sensing can reveal certain previously unobservable phenomena of our nature Seismic structure response Contaminant transportation Marine microorganisms Eco-system’s biocomplexity Application Domains

6 Sensor ADC Radio Battery Event detection Wireless communication with other nodes & base In-node processing Mote: Structure & Function

7 Enabling Technologies Technological advances have facilitated Smaller & cheaper electronic components Systems on a single chip Integrated low-power communication modules The above trends enabled WSN characterized by Smaller physical size Multi-functional behavior & concurrent operation Wireless communication

8 UCLA, 1996UCLA, 1998 Sensoria, 2001UCB, 2000 (Crossbow Tech.) It’s Just a Beginning

9 Time log (people per computer) “Streaming information to/from physical world” Number crunching Data storage Productivity Interactive Mainframe Minicomputer WorkstationPCLaptop PDA Roadmap

10  Flexible integration of sensors  Low-cost & energy-efficient processors  Robust communication over radio  Lifetime source with each mote A Dream Network!

11 4× Mica2 Motes 3× Sensor Boards (MTS300) Mote to PC Interface and Programming Board (MIB500) 2× Prototyping Boards (MDA500) 4× Mica2Dot Motes Experimental Hardware

12 Generations of Crossbow Motes

13 Mica2dot Battery Memory and Processor Sensor modules (externally integrated) 916/433 radio transceiver 10-bit ADC

14 Base Station Base station includes an interface board that allows Mote connectivity RS-232 serial programming interface Aggregation of network data on a PC

15  Sensor interfacing  Radio messaging  Routing  Power management  Time  Debug Required Software Services

16 Developed taking the following aspects into account Efficient resource utilization Small foot print to run on small processors Key Features: Set of services Simple operating system Open-source development environment nesC programming language Tiny Operating System (TinyOS)

17  Designed for low-power ad hoc WSN Responsive to stimuli, event oriented, scaleable  Key elements Sensing, computation, communication, power  Resource constrained Power, memory, processing  Adapt to changing technology Modularity & re-use TinyOS Architecture

18  Dialect of C  TOS syntax and structure aware –Variables, tasks, calls, events, signals –Component wiring  A pre-processor –nesC output is a c program file, which is compiled and linked using gcc tool nesC - The TinyOS Language

Application Example A Wireless Patient Monitoring System for the Ward of the 21 st Century of the Calgary Foothills Hospital

20 Doctors wish to continuously monitor variations in Temperature Heart rate Blood oxygenation Respiratory rate Toward this end, we developed a wireless framework. Patient’s Vital Medical Parameters

21 The Comprehensive Wireless Framework

22 Key Features The framework includes  Real-time sensing of patient’s vital parameters using precision-sensors interfaced to the motes  Wireless transmission of such critical information over radio frequencies to the base-station  Subsequent data processing on a PC to allow detection of medical emergencies and alerting of medical staff Note: Emergency detection is enabled using neural networks

23 Deliverables  A self-organizing wireless system capable of continuous patient-monitoring  Patients can move about in the hospital space, thanks to the “multi-hop” feature of WSN  A smart hospital bed with automation in terms of emergency detection

24 Temperature Sensor Ear temperature is quick to read and reliable! Our initial temperature sensor design involved: Thermistor modeling Linearization of output voltage Initial prototype is operational Future work will include packaging of thermistor using a silicon enclosure to protect from ear wax, and other non- intrusive methods of measuring body temperature

25 Heart Rate & Blood Oxygenation This instrument is being interfaced to a wireless mote

26  Potential applications for Ad hoc WSN are vast  Low-power transceiver designs become essential “Low-power” versus “Performance”  Fully-integrated low-power relaxation VCO Ken Townsend presented measured results Low-Power Transceivers

27  ADXL202AE dual-axis accelerometers (±2g) from Analog Devices are interfaced to the motes  Mica2dot motes are programmed to read sensor data via ADC3 and wirelessly transmit such data  Nominal reading of sensors is +1500mV at 0g. Sensitivity characteristic is ±150mV/g  Targeted application is the R&D of 6-axis motion of human feet that helps understand Parkinson’s Concept Demonstration

28 (1324,1245) Two types of nodes –Tripwire nodes that always sense Low-power presence sensing –Tracker nodes that sense on-demand Future of Power Management

29 Acknowledgements  NSERC  iCORE  TRLabs  Calgary Health Region

30 Conclusions  In this project, WSN technology is exploited for developing a framework for wireless patient-monitoring.  Results are expected to significantly help the healthcare personnel to cope with today’s shortage of resources.  The WSN paradigm and its advancements promise many other key applications in the healthcare sector.  The research area opens the doors for novel R&D activities in the microelectronics arena.