Wireless Sensor Networks Based On MICA Platform

1. Wireless Sensor Networks Based On MICA Platform Wei Zhou Sep 8, 2004

2. Overview and Goals • Big Idea: Ubiquitous sensing • How? • Necessarily “cheap” • This is the military / commercial. Cheap is relative. • Necessarily small • (more survivable, low profile, etc.) • Necessarily many • (economies of scale, higher measurement granularity, lower power comms, etc.) • Necessarily robust • Common case: no maintenance

3. Roadmap $$ + Network Embedded Systems Technology Program

4. Hardware Development Circle

5. Design Analysis • Integrate sensors, computation and communication in single unit • Basic board has radio, processor, memory • Sandwich sensor boards in layers • “Just like the rock…great cleavage” • Open-source hardware/software concept • Software is TinyOS (TOS) • Hardware design and Intel networking technology is licensed to Crossbow • Modular design allows fast development

6. 51-Pin I/O Expansion Connector Digital I/O 8 Analog I/O 8 Programming Lines Atmega103 Microcontroller DS2401 Unique ID Coprocessor Transmission Power Control Hardware Accelerators SPI Bus TR 1000 Radio Transceiver 4Mbit External Flash Power Regulation MAX1678 (3V) Mote Design: MICA • Three low-power modes • Idle: Processor is turned off • Power Down: Everything but the watch-dog is turned off • Power Save: Only asynchronous timer powered on • 100 mW power consumption • Processors, radio, typical sensor load • 30 uW power consumption • All components asleep

7. Motes

8. MICA2 • Crossbow 3rd generation wireless sensor • Design changes to MICA: • Processor now offers standalone boot-loader • New radio (Chipcon 1000) • 500 to 1000 ft. range, 38.4 Kbaud • Better noise immunity, linear RSSI • FM modulated (vs Mica AM) • Digitally programmable output power • Built-in Manchester encoding • Software programmable freq. • hopping within bands • Tiny OS v. 1.0 - improved network stack, debugging • Wireless remote programming* • 512 Kb serial flash

9. MICA2DOT • Crossbow 3rd generation wireless sensor • Similar feature set to MICA2 • Degraded I/O capabilities: 18 pins vs. 51 pins • 6 analog inputs, digital bus, serial or UART • Integrated temperature and battery voltage sensors, status LED • Battery is 3V coin cell instead of AA x 2 • 25 mm diameter, 6 mm height • Compatible with MICA2

10. Sensor Board Placement Microphone Sounder Magnetometer 1.25 in 2.25 in Temperature Sensor Light Sensor Accelerometer

11. Routing Tree Link Connectivity Ad hoc networking • Autonomous nodes self-assembling into a network of sensors • Sensor information propagated to central collection point • Intermediate nodes assist distant nodes to reach the base station • Connectivity and error rates used to infer distance

12. 2 1 3 2 1 Ad hoc networking • Each node needs to determine it’s parent and its depth in the tree • Each node broadcasts out <identity, depth, data> when parent is known • At start, Base Station knows it is at depth 0 • It send out <Base ID, 0, **> • Individuals listen for minimum depth parent 0

13. Panasonic CR2354 560 mAh Power breakdown • A one byte transmission uses the same energy as approx 11000 cycles of computation. • Lithium Battery runs for 35 hours at peak load and years at minimum load.

14. Sample tradeoffs

15. Operating system: TinyOS • Tiny Microthreading Operating System • Tiny - 4k OS + program memory limit • Microthreading - processor directly handles almost all data (radio, sensors, etc.) • OS - allows platform for future development convenient abstractions for hardware • Designed to do the job fast and then turn off everything allowed • Open source

16. What is TinyOS • TinyOS is an event-based operating environment designed to work with embedded network sensors • Designed to support concurrency intensive operations required by network sensors with minimal hardware requirements • TinyOS was initially developed by the U.S. Berkeley EECS department

17. Design Considerations • Make best use of most constrained asset: battery power • Network self-configuration • Manage complexity, respond to unplanned events • Sensor self-configuration • “Glue and go” • Real-time • Limited buffering available • Network robustness and maintenance • Multiple points of failure, self-healing ability

18. Sample Application: Tiny DB • Imposes SQL-like querying ability on nodes • Treats distributed network like a database (!) • Allows specification of which data should be sent, update rate, etc. • Filters and aggregates before displaying on PC screen (Java interface) • Saves bandwidth and power by allowing nodes to only transmit requested data • Graphical query-builder • Download self-configuring runtime to motes, no C coding

19. Potential applications at ISU • Building various monitor-and-alarm systems • Monitor-and-alarm testbed for power systems • Accelerometer • Extremely sensitive sensor (Voltage, Current, etc.) • Interface with control system • What device you have? Is it possible to integrate it with MICA to make a monitoring system? • Testing new research ideas • Data integration/dissemination • Information delivery/routing • Localization • Sensor network security • More…

20. MICA Motes Conclusion • Sensor Hardware • Cheap, publicly-available, modular, integrated, power-efficient, extensible, tiny • Sensor Software • Free, open-source, modular, abstract, power-efficient, extensible, small • Cost • Potentially cheap enough for densely deployment • Expected $1 for each radio board in NEXT generation

21. More Info. • http://www.tinyos.net/ • http://webs.cs.berkeley.edu/ • www.xbow.com • http://mail.millennium.berkeley.edu/pipermail/tinyos-help • http://nescc.sourceforge.net/