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