pete secor. wireless basics industry standards for rf transmission ieee 802.11 wifi; bluetooth ieee...

Pete Secor

WIRELESS BASICSIndustry standards for RF transmission

IEEE 802.11 WiFi; BluetoothIEEE 802.15.4 Low Power Low Data Rate

Platform for ZigBee & Wireless HART & Evergreen Telemetry

Hierarchy of layers--rule sets—foundation at bottomApplications (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.)

WIRELESS SENSOR NETWORKS (WSN)

Key terms: mesh; IEEE 802.15.4; ZigBee; interoperable

ComponentsEnd node (sleeps), router/repeater, coordinatorNode contains: radio, antenna, sensing elec.;

encl. For sensing and/or actuatingLine powered and/or battery

Built-in system monitors and reliability featuresMaster intelligence

Network Diagram

802.15.4 LOW POWER & LOW DATA RATE

Battery-based appsShort, infrequent transmissions, not time-critical

xxx bytes per transmission, not x Mb/s.Handshaking and error detection—resend if necessaryDesigned to withstand interference, not overpowerEnd 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

ISM Frequency SpectrumIEEE 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

wallsAmplified range measured in miles

ZigBee AllianceFounded 2002HVAC FocusKey members:

Emerson, Itron, Landis & Gyr, Schneider, Aclara

AEP, Consumer’s Energy, Edison, BC HydroEaton, Crestron, Distech, Echelon, GEJohnson Controls, Siemens, HoneywellAtmel, Intel, Sharp, Sony, Samsung, NEC, OkiHundreds of others

ZigBee AllianceIndustry Liasons

American Telemedicine; Continua Health Alliance

BACnet; WiFi; HomePlug Powerline AllianceDemand Response and Smart Grid CoalitionElectric Power Research Institute; NEMAEuropean Smart Metering AssociationSociety of Automotive Engineers (electric vehicles)ANSI; Internet Engineering Task ForceContinental Automated Buildings Assoc.Consumer Electronics Assoc. (RF4CE)

ZIGBEE KILLER APPSHVAC monitoring and control

Thermostats & VAV’sSmart Energy

Term is widely used with different meaningsOne app: Connects electric meter to t-stat &

appliances Utility can control home remotely—temp, pool pump, w. heat

RF4CENext generation remote control for homeNo line-of-sight issuesContemporary display & selection

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 slightlyReflections, phase change add/subtract signal

MoistureFailure of a router/repeater.Battery failureRange reduction for various reasons

ENSURE WSN SUCCESSExperience generally problem-freeAvoid long range, edge of range operationInstall extra router/repeatersAwareness

Range issues, number of hopsSlight 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

SUCCESSFUL WIRELESS SENSING

Questions?Pete Secor

pete.secor@evergreentelemetry.com