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TIPS FOR SUCCESSFUL WIRELESS SENSING

TIPS FOR SUCCESSFUL WIRELESS SENSING. Pete Secor. WIRELESS BASICS. Industry standards for RF transmission IEEE 802.11 WiFi; Bluetooth IEEE 802.15.4 Low Power Low Data Rate Platform for ZigBee & Wireless HART & Evergreen Telemetry Hierarchy of layers--rule sets—foundation at bottom

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TIPS FOR SUCCESSFUL WIRELESS SENSING

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  1. TIPS FOR SUCCESSFUL WIRELESS SENSING Pete Secor

  2. WIRELESS BASICS • Industry standards for RF transmission • IEEE 802.11 WiFi; • Bluetooth • IEEE 802.15.4 Low Power Low Data Rate • Platform for ZigBee & Wireless HART & Evergreen Telemetry • Hierarchy of layers--rule sets—foundation at bottom • Applications (Smart Energy App passes rate info) • Network (Customized by ZigBee, Wireless Hart, etc.) • Data Link (IEEE 802.15.4 defines this layer) • PHY (Physical, radio, antenna, connector, etc.)

  3. Wireless Comparison

  4. WIRELESS SENSOR NETWORKS (WSN) • Key terms: mesh; IEEE 802.15.4; ZigBee; interoperable • Components • End node (sleeps), router/repeater, coordinator • Node contains: radio, antenna, sensing elec.; encl. • For sensing and/or actuating • Line powered and/or battery • Built-in system monitors and reliability features • Master intelligence

  5. Network Diagram

  6. 802.15.4 LOW POWER & LOW DATA RATE • Battery-based apps • Short, infrequent transmissions, not time-critical • xxx bytes per transmission, not x Mb/s. • Handshaking and error detection—resend if necessary • Designed to withstand interference, not overpower • End node battery example—temperature sent 1x/min. • Lithium button cell 1000 mA-hr battery lasts 5 years. • This platform selected by ZigBee Alliance • Ideal building application—wireless thermostats

  7. ISM Frequency Spectrum • IEEE 802.15.4 specifies these frequency channels: • 0 at 868.3 MHz (Mostly EU only) • 1-10 at about 915 MHz (Mostly N. Amer. Only) • 11-26 near 2.4 GHz. (Available worldwide) • WiFi on same channels—different wave characteristics • ZigBee Alliance tested WiFi interference • Some transmissions repeated; none lost. • ZigBee scans for low energy channel at start-up. • Range at 2.4 GHz 50 to 100 feet per hop, through walls • Amplified range measured in miles

  8. ZigBee Alliance • Founded 2002 • HVAC Focus • Key members: • Emerson, Itron, Landis & Gyr, Schneider, Aclara • AEP, Consumer’s Energy, Edison, BC Hydro • Eaton, Crestron, Distech, Echelon, GE • Johnson Controls, Siemens, Honeywell • Atmel, Intel, Sharp, Sony, Samsung, NEC, Oki • Hundreds of others

  9. ZigBee Alliance • Industry Liasons • American Telemedicine; Continua Health Alliance • BACnet; WiFi; HomePlug Powerline Alliance • Demand Response and Smart Grid Coalition • Electric Power Research Institute; NEMA • European Smart Metering Association • Society of Automotive Engineers (electric vehicles) • ANSI; Internet Engineering Task Force • Continental Automated Buildings Assoc. • Consumer Electronics Assoc. (RF4CE)

  10. ZIGBEE KILLER APPS • HVAC monitoring and control • Thermostats & VAV’s • Smart Energy • Term is widely used with different meanings • One app: Connects electric meter to t-stat & appliances • Utility can control home remotely—temp, pool pump, w. heat • RF4CE • Next generation remote control for home • No line-of-sight issues • Contemporary display & selection

  11. Your App--What Can Go Wrong? • Interference--WiFi, oven, cordless phone, other. • Absorption--Water heater; Human bodies in hallway. • Move or eliminate a reflective surface • Change position slightly • Reflections, phase change add/subtract signal • Moisture • Failure of a router/repeater. • Battery failure • Range reduction for various reasons

  12. ENSURE WSN SUCCESS • Experience generally problem-free • Avoid long range, edge of range operation • Install extra router/repeaters • Awareness • Range issues, number of hops • Slight position change can help or hurt. • Battery level—end nodes sleep—coord & routers don’t • Transmission schedule (2 seconds vs. 1 min. vs. 10 min.) • New emitter or change in environment causes problems • Cycle power, rescan channels for energy, select new channel

  13. SUCCESSFUL WIRELESS SENSING Questions? Pete Secor pete.secor@evergreentelemetry.com

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