The Mote Revolution Low Power Wireless Sensor Network

The Mote Revolution: Low Power Wireless Sensor Network Devices University of California, Berkeley Joseph Polastre Robert Szewczyk Cory Sharp David Culler “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 Only a relevant subset of slides

Outline Trends and Applications n Mote History and Evolution n Design Principles n Telos n “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 2

Faster, Smaller, Numerous Moore’s Law ¨ n “Stuff” (transistors, etc) doubling every 1 -2 years Bell’s Law ¨ New computing class every 10 years Streaming Data to/from the Physical World log (people per computer) n year “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 3

e n m o i i t s ife ci L e r P n& le & a o cy i e c t t n c S a e e t R & a n ty i L e n y l l t i o i p w b c s Lo Mo Dis Sam Den Applications n Environmental Monitoring Habitat Monitoring ¨ Integrated Biology ¨ Structural Monitoring ¨ n Interactive and Control Pursuer-Evader ¨ Intrusion Detection ¨ Automation ¨ “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 4

Open Experimental Platform Services Networking Telos 4/04 Robust Low Power 250 kbps Easy to use Tiny. OS We. C 99 “Smart Rock” Rene 11/00 Dot 9/01 Small microcontroller 8 k. B code 512 B data Simple, low-power radio 10 kbps ASK Designed for experimentation EEPROM (32 KB) -sensor boards Simple sensors -power boards Demonstrate scale Mica 1/02 Mica 2 12/02 38. 4 kbps radio FSK NEST open exp. Platform 128 k. B code, 4 k. B data 40 kbps OOK/ASK radio 512 k. B Flash Spec 6/03 “Mote on a chip” Commercial Off The Shelf Components (COTS) “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 5

Mote Evolution “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 6

D/A A/D Microcontroller External Memory n n Digital I/O ports Radio Transceiver Analog I/O Ports 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) Sensor Nuwan Gajaweera Presentation 7

Low Power Operation n Efficient Hardware ¨ Integration and Isolation n Complementary functionality (DMA, USART, etc) ¨ Selectable Power States (Off, Sleep, Standby) ¨ Operate at low voltages and low current n Run to cut-off voltage of power source n Efficient Software ¨ Fine grained control of hardware ¨ Utilize wireless broadcast medium ¨ Aggregate “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 8

Typical WSN Application Periodic ¨ ¨ ¨ Triggered Events ¨ ¨ Detection/Notification Infrequently occurs n n But… must be reported quickly and reliably Long Lifetime Months to Years without changing batteries ¨ Power management is the key to WSN success ¨ wakeup n Data Collection Network Maintenance Majority of operation Power n processing data acquisition communication sleep Time “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 9

Design Principles n Key to Low Duty Cycle Operation: ¨ Sleep – majority of the time ¨ Wakeup – quickly start processing ¨ Active – minimize work & return to sleep “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 10

Sleep n Majority of time, node is asleep ¨ >99% n Minimize sleep current through ¨ Isolating and shutting down ¨ Using low power hardware n Need RAM retention n individual circuits Run auxiliary hardware components from low speed oscillators (typically 32 k. Hz) ¨ Perform ADC conversions, DMA transfers, and bus operations while microcontroller core is stopped “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 11

Telos Platform n A new platform for low power research ¨ n IEEE 802. 15. 4 ¨ USB ¨ Monitoring applications: n n n Environmental Building Tracking n Long lifetime, low power, low cost n Built from application experiences and low duty cycle design principles n Robustness ¨ ¨ ¨ IEEE 802. 15. 4 Zig. Bee CC 2420 radio ¨ Frame-based ¨ 250 kbps ¨ 2. 4 GHz ISM band ¨ n n Standards Based TI MSP 430 ¨ Integrated antenna Integrated sensors Soldered connections Ultra low power n n n 1. 6 m. A sleep 460 m. A active 1. 8 V operation Open embedded platform with open source tools, operating system (Tiny. OS), and designs. “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 12

Minimize Power Consumption n Compare to Mica. Z: a Mica 2 mote with AVR mcu and 802. 15. 4 radio n Sleep ¨ ¨ ¨ n Wakeup ¨ ¨ ¨ n Majority of the time Telos: 2. 4 m. A Mica. Z: 30 m. A As quickly as possible to process and return to sleep Telos: 290 ns typical, 6 ms max Mica. Z: 60 ms max internal oscillator, 4 ms external Active ¨ ¨ ¨ Get your work done and get back to sleep Telos: 4 -8 MHz 16 -bit Mica. Z: 8 MHz 8 -bit “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 13

CC 2420 Radio IEEE 802. 15. 4 Compliant n CC 2420 ¨ Fast data rate, robust signal n n ¨ Low Voltage Operation n ¨ 250 kbps : 2 Mchip/s : DSSS 2. 4 GHz : Offset QPSK : 5 MHz 16 channels in 802. 15. 4 -94 d. Bm sensitivity 1. 8 V minimum supply Software Assistance for Low Power Microcontrollers n n 128 byte TX/RX buffers for full packet support Automatic address decoding and automatic acknowledgements Hardware encryption/authentication Link quality indicator (assist software link estimation) ¨ samples error rate of first 8 chips of packet (8 chips/bit) “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 14

Power Calculation Comparison Design for low power n Mica 2 (AVR) ¨ ¨ ¨ n 0. 2 ms wakeup 30 m. W sleep 33 m. W active 21 m. W radio 19 kbps 2. 5 V min n Mica. Z (AVR) ¨ ¨ ¨ 2/3 of AA capacity 0. 2 ms wakeup 30 m. W sleep 33 m. W active 45 m. W radio 250 kbps 2. 5 V min n n Telos (TI MSP) ¨ ¨ ¨ 0. 006 ms wakeup 2 m. W sleep 3 m. W active 45 m. W radio 250 kbps 1. 8 V min 2/3 of AA capacity n 8/8 of AA capacity Supporting mesh networking with a pair of AA batteries reporting data once every 3 minutes using synchronization (<1% duty cycle) 453 days 328 days 945 days “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 15

Sensors n Integrated Sensors ¨ Sensirion SHT 11 n n n ¨ n Humidity (3. 5%) Temperature (0. 5 o. C) Digital sensor n n Total solar light Silicon diode 6 ADC channels 4 digital I/O Existing sensor boards n Photosynthetically active light Silicon diode Hamamatsu S 1337 -BQ Expansion ¨ ¨ ¨ Hamamatsu S 1087 n ¨ n n n Magnetometer Ultrasound Accelerometer 4 PIR sensors Microphone Buzzer acoustic mag ultrasound dot “The Mote Revolution: Low Power Wireless Sensor Network Devices” Hot Chips 2004 : Aug 22 -24, 2004 16