Post on 25-Jun-2020
transcript
WirelessCommunication
CS447– WirelessEmbeddedSystems
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,20181
802.11– WiFi
• WLAN– wirelesslocalareanetwork• 2.4GHzradioband(mosttypical)• 14channels• MediaAccessControl(MAC),PhysicalLayer(PHY)standards
January31,20182
802.11– WiFi
• Accesspoint – allowsWiFi devicetoconnecttowirednetwork• APssupportmultipleconnecteddevices
January31,20183
802.11– WiFi
• Ad-hoc– allowsdirectcommunicationbetweendeviceswithout anintermediaryaccesspoint• Aka“ad-hocWiFi”
January31,20184
802.11– WiFi
Wi-Fihasmanymoredetails• Encryption• SSID• Rangeextenders• …
IoT LabhasXbee WiFimodulesyoucanrent• Configurationcanbechallenging..
January31,20185
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,20186
Bluetooth
• Intendedforshortdistances• 2.4GHzradioband• PAN– PersonalAreaNetwork• IEEE802.15.1standard(historical)• 79designatedchannels• Datarate:~25Mbits /second• Range:~10meters
January31,20187
Bluetooth
• Master/Slavearchitecture• Mastercancommunicatewithupto7devices• Piconet – ad-hocnetworkusingBluetoothtechnology• Round-robin schedulingofslavecomm• Hasbroadcastmode(littleused)
ManyBluetooth“breakout”modulesavailable• E.g.,Sparkfun BlueSMiRF Silver~$25
January31,20188
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,20189
WiMAX
• WorldwideInteroperabilityforMicrowaveAccess• IEEE802.16standardforPHY,MAClayers• “Lastmilewirelessbroadbandaccess”• NotareplacementforWiFi• AlternativetocableorDSL• Datarate:~30Mbit/sec• Range:~10miles• DoesNOTrequirelineofsight(LOS)
January31,201810
WiMAX
Usages:• BackhaulservicetotransferdatawithinanISPnetwork
• Provideinternetaccessforusersinremotelocations(layingcabletooexpensive)
• Formofmobileinternetaccess(competesw/cellular,satellite)
January31,201811
WiMAX
Howtouse:• Basestations– installedbyserviceproviders• Receivers– installedwithinclients
January31,201812
WiMAX
January31,201813
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,201814
Cellular
• 2G,3G,4G=>800MHzfrequencyband• Datarate(4G):100Mbits /sec(max)forhighmobility• Datarate(4G):1Gbit /sec(max)forlowmobility• Manyprotocols:GSM,LTE,GPRS
Manycellmodemsavailable:• E.g.,adafruit FONA3G+GPS
January31,201815
Cellular
GSM:GlobalSystemforMobile(Communication)• Europeanstandard• 2nd generationdigitalcellnetworkprotocol• >90%marketshare• 190+countries
January31,201816
Cellular
LTE:Long-TermEvolution• Commonlymarketedas4GLTE• Goal:increasecapacityandspeedofwirelessdatanetworks• Utilizesdigitalsignalprocessingtechniquesandmodulations• LTEincompatiblewith2Gand3Gnetworks• Mustbeonseparateradiospectrum
January31,201817
Cellular
GPRS:GeneralPacketRadioService• Packetorientedmobiledataservice• 2Gand3Gnetworks• ExtendsGSM• SMSmessaging(upto30perminute)• “alwayson”internet
• E.g.,Sparkfun GSM/GPRSModule
January31,201818
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,201819
Satellite
E.g.,IridiumNetwork• 66activesatellites• Transceiversanywhereonearth’ssurface• Voiceanddatacoverageforsatellitephones• ~$1.00perminuteofphoneuse• SupportsTCP/IP
January31,201820
Satellite
E.g.,Iridium9603• Transceiversarepowerhungry(~1.3Ampsintransmitmode)• Relativelyslowdatarates(~3kbits /sec)• ~1secondround-triplatency
E.g.,Sparkfun RockBLOCK Mk2• Iridium9602brokenout
January31,201821
Outline
• 802.11- Wi-Fi• Bluetooth• WiMAX• Cellular• Satellite• 802.15.4
January31,201822
802.15.4
• Radiosyou’lluse• Reliable• Powerefficient• Lowdatarate• Designedforwirelesssensornetworks(WSNs)• IEEE802.15.4standardforMACandPHY
January31,201823
802.15.4
• 900MHzor2.4GHzfrequencybands• 16-bitaddressing(short)• Ifneeded,64-bitextendedaddressing• Linkqualitymetrics• CarrierSenseMultipleAccesswCollisionAvoidance(CSMA-CA)• Built-inacknowledgements(acks)fortransferreliability
January31,201824
802.15.4
Startopology:• Communicationestablishedbetweendevicesandsinglecentralcontroller(PANcoordinator)
• Controllerroutespacketstoendpoints(viaaddressing)
January31,201825
802.15.4
Peer-to-Peertopology:• Anydeviceabletocommunicatewithanyotherdevicewithinrange• P2Pallowscomplexnetworkformations(e.g.,meshnetwork)• Allowsmultiplehopstoroutemessages(applicationlayer)
January31,201826
802.15.4
PHY– PhysicalLayer• Enablestransmission/receptionofPHYprotocoldataunits(PPDUs)acrossphysicalradiochannel
Features:• Activates/deactivatesofradiotransceiver• Energydetection• Channelselection• Clearchannelassessment• LQI– linkqualityindicator(forRSSI)
January31,201827
802.15.4
MACsublayer• Enablestransmission/receptionofMACprotocoldataunits(MPDUs)acrossthePHYdataservice
Features:• Beaconmanagement• Channelaccess• Framevalidation• Ack• Hooksforapplication-layersecurity
January31,201828
802.15.4
Xbee 802.15.4Series1• Indoorrange:200’• Outdoorrange:4000’• Datathroughput:upto96,000bits/second• UARTdatarate:57,600baud(typical)
• Transmitcurrent:~50mApeak• Receivecurrent:~30mA• Operatingvoltage:3.3V
January31,201829
802.15.4
Xbee 802.15.4Series1• ”Transparent”operatingmode(default)• Actslikeinvisiblewire
OthermodesincludeAPIandCommand(advanced)• APImodeallowsmoreadvancedoperations• E.g.,addressingspecificradiomodules
January31,201830
802.15.4
Xbee 802.15.4Series1• Thisclass:applicationlayeraddressing• Basestationradio“broadcasts”• Allend-pointsreceivepacket• Usesapplicationlevellogictodetermineaddressing…
January31,201831
802.15.4
Xbee 802.15.4Series1• WillconnectXbee radiotocomputerviaUSBdongle• Computerwillactasbasestation
January31,201832
802.15.4
Xbee 802.15.4Series1• WillConnectXbee toArduinowithshield• Arduino(s)actasendpointdevicesforWSN• Shieldhasswitch:DLINE,UART• DLINE – communicateb/tcomputerandArduinoUSB• UART – communicateb/tXbee radio
January31,201833
802.15.4
Xbee 802.15.4Series1• YouMUSTconfiguretheradiosbeforeusing
• X-CTUsoftwarepackagefromDigi• https://www.digi.com/products/xbee-rf-solutions/xctu-software/xctu
Mustsetfollowingparameters:• CH – radiochannel• ID – PANID• MY – unique16-bitaddressforeachradio• DL – 16-bitdestinationaddressforeachradio• BD – serialbaudrate
January31,201834
802.15.4
XCTUsoftwareprimer–• ConnectXbee radiotoXbee USBdongle• ConnectUSBdongletocomputer• Download/openXCTU
January31,201835
Click “Discover Devices”
Select port
Click Next >
Select multiple Baud Rates:960057600115200
Click Finish
January31,201839
XCTU will search for connected radios…
January31,201840
Radio found, select and click “Add selected devices”
January31,201841
Device has been added..
Click on it to configure.
January31,201842
Parameters that can be configured…
January31,201843
E.g., click the ID text field to edit configure the PAN ID of your WSN…
January31,201844
Click Write to configure the radio
January31,201845
Repeat for CH, MY, DL, BD
NOTE: You’ll have to configure allradios in your WSN
802.15.4
CH– channel• sameforallradios inWSN
ID – PANID• sameforallradios inWSN• uniqueforyourteam
BD– baudrate• sameforallradios inWSN(e.g.,57600)
January31,201846
802.15.4
MY– 16-bitsourceaddress• EachradioinWSNmusthaveuniqueMYaddress,e.g.,• 0xBACE forbasestationradio• 0x0001forwirelessnode#1• 0x0002forwirelessnode#2• 0x0003forwirelessnode#3
January31,201847
802.15.4
DL– 16-bitdestinationaddress• Basestationradiomustbroadcast(0xFFFF)• Wirelessnodesmatchbasestation’sMYaddress(e.g.,0xBACE)
January31,201848