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Commercial Wireless Sensor Networks: Low Power Hardware, Efficient Stacks

Commercial Wireless Sensor Networks: Low Power Hardware, Efficient Stacks. Kris Pister Founder & Chief Technologist, Dust Networks Prof. EECS, UC Berkeley. Outline. Applications Standards Technology. 2. WSN Timeline. 3. Wireless Sensors For Industrial Process Automation.

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Commercial Wireless Sensor Networks: Low Power Hardware, Efficient Stacks

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  1. Commercial Wireless Sensor Networks:Low Power Hardware, Efficient Stacks Kris Pister Founder & Chief Technologist, Dust Networks Prof. EECS, UC Berkeley

  2. Outline • Applications • Standards • Technology 2

  3. WSN Timeline 3

  4. Wireless Sensors For Industrial Process Automation source: Emerson Process Management, 2007 4

  5. Wireless HART Architecture source: ABB, 2010 5

  6. Power Sources: Battery & Energy Scavenging Siemens GE • Battery • 4-20 mA loop • Solar Emerson • Battery • 4-20 mA loop • Thermal • Battery • Vibration • Routing node power: 50uA…100uA @ 3.6V • C-cell lithium lifetime: 7 years • Scavenger lifetime: ? 6

  7. Wheeling-Pittsburgh Steel • Need to monitor temp, coolant, lubrication • Hot slag defeated wired solutions • 5% improvement in productivity (reduced maintenance) 7

  8. Lime Kiln at Pulp & Paper Mill • 5% throughput improvement (reduced process time) 8

  9. Wireless Sensors Grane Platform, North Sea • 90% reduction in installation cost 9

  10. Chevron’s Richmond Refinery 1 km 10

  11. Richmond Refinery Wireless Umbrella • Next • Fence monitoring • H2S, Volatile Organic Compounds • Location 5 km2, 90% coverage 11

  12. Smart Building: Federspiel Controls • Heating, Ventilation, Air Conditioning optimization to conserve energy • California Tax Board savings: 459,000 kWh/yr, $55,000/yr (1 yr payback) • No wires, no interruption to data center operations 12

  13. Smart Cities: Streetline Networks Wireless sensor node 13

  14. Finding Parking, Optimizing Enforcement 14

  15. Smart Rail • Multiple sensors per car • Every car is a network • WAN gateway to internet database, analytics 15

  16. Bearing Failure  High Cost 16

  17. Zigbee • The big three • Zigbee Pro / SE1.0 • Zigbee RF4CE • Home entertainment control • Guarantees that cell phones will have 15.4 radios • Zigbee IP / SE2.0 • http, TCP, TLS, DHCP, … • Zigbee Green Power • All use powered routers • Interoperability • Routing • Provisioning 17

  18. Time Synchronized Mesh Protocol (TSMP & TSCH) • Basis of several Industrial Automation Standards • IEC 62591 (WirelessHART) • ISA100.11A • WIA-PA (China) • MAC is standardized in 802.15.4E (TSCH) • Multiple network vendors: Dust, Nivis, STG, … 18

  19. TSMP Foundations • Time Synchronization • Reliability • Power • Scalability • Reliability • Frequency diversity • Multi-path fading, interference • Spatial diversity • True mesh (multiple paths at each hop) • Temporal diversity • Secure link-layer ACK • Power • Turning radios off is easy… 19

  20. Power-optimal communication A B A wakes up and listens B transmits B receives ACK A transmits ACK Worst case A/B clock skew • Assume all motes share a network-wide synchronized sense of time, accurate to << 1ms • For an optimally efficient network, mote A will only be awake when mote B needs to talk Expected packet start time 20

  21. Packet transmission and acknowledgement Radio TX startup ACK RX Packet TX Radio TX/RX turnaround Mote Current (2011): 50 mJ (2007): 200 mJ Energy cost (2003): 800 mJ 21

  22. Idle listen (no packet exchanged) Empty receive Radio RX startup Mote Current (2011): 15 mJ (2007): 60 mJ Energy cost (2003): 200 mJ 22

  23. Mesh Networking • 2.4 GHz 802.15.4 PHY; 15.4E MAC; 6LoWPAN; UDP • Time Synchronized for low power & scalability • All nodes run on batteries, for 5-10 years, or on scavengers indefinitely • Channel Hopping and full mesh for reliability • 99.999% “best effort” packet delivery IP Gateway IEEE 802.15.4 Mote Sensor 23

  24. Mote-on-chip current vs. sample date RX Current 0dBm TX Current CEL Freescale Ember Ember MSP430 +CC2420 TI TI Freescale Jennic Jennic Dust Networks Dust Networks 24

  25. Summary • Real applications exist • Standards are a reality • Existing production networks have > 99.999% reliability > 5 year battery life 25

  26. Backup slides 26

  27. Evolving information flow in WSN DB Business logic Custom APP APP Manager LBR IPv6, native DB fmt. Proprietary network & data fmt. Network stack Network stack Application Serial API Sensor mP Sensor Application Sensor 27

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