PUBLIC DASH7, PASSIVE RFID AND LPWAN PROF. MAARTEN WEYN - MICHAEL ANDRE
PUBLIC
DASH7,PASSIVERFIDAND LPWANPROF.MAARTENWEYN- MICHAELANDRE
THEINTERNETOFTHINGS
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WIRELESSLYCONNECTINGATHING…
ThingWhat frequency is used?
How does transmission work?How is link established?
How is network formed?How do devices join?
How to send packet from A to B?How to set up connection?
…
What is a light bulb?What is on/off?What is dim?
Wireless communication
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MEANSSELECTINGANAPPROPRIATETECHNOLOGY
…andunderstandinglimitationsandtrade-offs
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WIRELESSLANDSCAPE
RANGECAPABILITY
BANDW
IDTH
LPWAN featuresLongrange
Lowdatarate
Lowpower
Licensefree/licensed
Differentsystemmodels
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WIRELESSTECHNOLOGY
WIRELESSTRADE-OFFS
$$$Licensed/UnlicensedSpectrum
LicenseCost/ISMregulations/Collisions
Range:higherfrequencies resultinshorterrange,morecomplexcodingreduces range
Data rate:moreBWoradvancedcodingwithingivenBWresultsinhigherachievabledataratesofsystem
EnergyconsumptionTx duration– Rxschedulingandduration
TopologyStar– Mesh– PointtoPoint
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THECONTENDERS
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SIGFOX
Radio implementing patented technology
(< 5EUR)
E.g. TI, Silicon Labs, Atmel
SigFox ReadyTM
device with subscription
Class 0, 1, 2 or 3(0 = best RF performance)
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SIGFOX – COVERAGETODAY
Source: www.sigfox.com/coverage
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SIGFOX – TECHNICALINFORMATION
• 868 MHz (EU)• Max radiated power: 14dBm• Max Duty Cycle allowed: 1%• Modulation: DBPSK @ 100bps using 100Hz channel in
200kHz band• Max. 140 msg/day of 12 bytes payload
(→ 2s TX time!) to meet duty cycle• TX: msg is sent 3 times at diff. pseudo-random freq. to
ensure delivery (no collision avoidance or recovery)• RX: every BS listens to 200kHz band• Private key per device + hash for auth.
UPLINK(DEVICE→BS)
• 869 MHz band (EU)• Max radiated power: 27dBM• Max duty cycle: 10%• Modulation: GFSK @ 600bps using 600Hz channel• Max. 4 msg/day/device of 8 bytes• High sensitivity of BS (-142dBm)• TX
• Timing initiated by device• Base station adapts to frequency
(+offset) of node
DOWNLINK(BS→DEVICE)
• Based on ETSI Low Throughput Network (LTN) + patented features• Ultra Narrow Band (UNB)
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SIGFOX – UPLINKSCALABILITY
MESSAGE TRANSMISSION / DEVICE• Total msg size (12B payload) = 26B• TX time for 1 msg @ 100bps = 2.08s• TX time for 3 transmissions (with
45ms TX offset) = 6.33s• 10msg/day = 63.33s air
time/device/day
DEVICE → BS (no collisions, i.e. theory)
TOTAL AVAILABLE AIR TIME / DAY / BS• 200 channels of 100Hz (within 200kHz)
→ 17.280.000s air time
MAX. DEVICES / BS = 272.856# Unique msgs / 60s = +/- 1895
assuming perfect collision-free system
Source: SigFox
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SIGFOX – UPLINKSCALABILITY
DEVICE → BS (collisions) - Simulation
Source: Maarten Weyn (mweyn.wesdec.be)
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1. LoRa =PHY1. Novelradiomodulation patentedbySemtech,basedonChirpSpreadSpectrum(CSS),with
veryhighsensitivity
2. LoRaWAN =communicationprotocol (MAC)andsystemarchitectureforthenetwork1. Open,definedbyLoRa Alliance
Technology Rx sensitivity Datarates
Wi-Fi -84dBm <54Mbps
BLE -90dBm <1Mbps
-109dBm <80Kbps
LoRa -138dBm 300bps– 10KbpsSource: i2CAT
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Freq.(MHz)/BW Conditions(Pwr/DC)
OrthogonalSpreading factors
868.10(g1)/125kHz
14dBm@1%
7-12
868.30(g1)/125kHz 7-12
868.50 (g1)/125kHz 7-12
LORA - SPECTRUMUSAGEANDDATARATESSUB-GHZ BAND: ETSI ERC 70-03 (EU)
Sub-band Freq.Range (MHz) Conditions (Pwr/DC)
g 863- 868 14 dBm@1%or LBT+AFA
g1 868–868.6 14dBm@1%or LBT+AFA
g2 868.7–869.2 [email protected]%or LBT+AFA
g3 869.4–869.65 27dBm@10%or LBT+AFA
g4 869.7- 870 14dBm@1%or LBT+AFA SpreadingFactor(SF)
BitRate
SF=12 250 bps
SF=11 440bps
SF=10 980bps
SF=9 1.7Kbps
SF=8 3.1Kbps
SF=7 5.4Kbps
Range
LBT+AFA = Listen Before Talk with Adaptive Frequency Agility
LoRaWAN default channels
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Europe North America
Frequencyband 867-869MHz 902-928MHz
Channels 8+1+1 64+8+8
ChannelBWUp 125/250kHz 125/500kHz
ChannelBWDown 125kHz 500kHz
TXPowerUp +14dBm +20dBmtyp.(+30dBm allowed)
Tx PowerDown +14dBm +27dBm
SFUp 7-12 7-10
Datarate 250bps–50kbps 980bps-21.9kbps
Linkbudgetup 155dB 154dB
Linkbudget down 155dB 157dB
LORA - SPECTRUMUSAGEANDDATARATESEU VS NORTH AMERICA
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LORA - DATARATEVERSUSRANGERANGE VERSUS SPREADING FACTOR
Source: ActilitySF7--SF8--SF9--
SF10--SF11--SF12--
SF7--SF8--SF9--
SF10--SF11--SF12--
SF7--SF8--SF9--
SF10--SF11--SF12--
0s 1s 2s 3s 4s
Chan
nel1
Chan
nel2
Chan
nel3
Time
Air time
Source: i2CAT
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LORAWAN – THEORETICALTHROUGHPUTNODE
Back of envelope calculations for max data throughput per hour:
SF Data rate [b/s]
Max. #b/h
Max. data length [B]
Max. Pt Size [B]
Min. Over-head
Max #Pt/h
Max data/h [B/h]
Max TX energy [J]
12 250 9000 51 80 36.2% 14 714 3.5
11 440 15840 51 80 23.8% 24 1224 3.4
10 980 35280 51 80 23.8% 55 2805 3.5
9 1760 63360 115 144 20% 55 6325 3.5
8 3125 112500 222 251 12% 56 12432 3.5
7 5470 196920 222 251 12% 98 21756 3.5
20B PHY header9B MAC header
868MHz: 1% RDC
14dBm TX power29.6 mA supply current
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LORAWAN – SCALABILITY
COLLISIONS - SIMULATION ALOHAALOHA CHANNEL ACCESS
ASSUMPTION• If you have data, send it• If another station transmits, then
collision
THEORETICAL PERFORMANCE OF ALOHA SYSTEM
With air utilisation lower than 18%, 97% of transmissions are likely to
succeed!
Air utilization can be reduced by using lower SF, i.e. most nodes in
vicinity of BS or more BSs!Source: Maarten Weyn (mweyn.wesdec.be)
No collision avoidance mechanism
RandomlychosenSF
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§ WirelessSensorandActuatorNetworkProtocol (WSAN)§ OriginatesfromISO18000-7(“dash7”)
§ describes theparameters foractiveairinterface communications at433MHz(2008- 2009)
§ Extended tosupportIoTfunctionalities§ Nowsupportallsub-GHzISM/SRDbands§ Starortreenetworktopology (nomesh)§ v1.1ofthespecpublishedinQ12017.§ ActivemembersoftheProtocolActionGroup:
Wizzilab,UniversityofAntwerp,WroclawTechnicalUniversityandCORTUS
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OPENSTANDARD OFULTRALOWPOWERMID-RANGESENSORANDACTUATORCOMMUNICATION
OpenStandard
VeryLow
Power
StructuredData
Low cost
Security
Mid/LongRange
Fullstack
NETWORKTOPOLOGY
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Distance– Complexity– Energy– Latency
Tree MeshStar
PassiveRFIDTagscanonlybereadintheintermediateproximityofareader
ActiveRFIDLongerrangeinterrogators–Master/Slave
DASH7Simplerouting(2hops)subcontrollers arepowerbutonlyfewareneededTag-to-Tag&Tag-Talk-First
MeshRangedependsonnumberofrouternodes
Congestion– RoutingComplexity–LatencyRoutersneedtobepoweredEachhopconsumesenergy
FULLSTACKSPECIFICATION
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APP
PRES
SESS
TRAN
NETW
DLLMAC
PHY
ALP
FileNotif.
SessionStack
D7AQP
D7AAdvp D7ANP
SCAN
BG FGCSMA-CA SUBNET
PN9 (G)FSK CCA Sub-GHz433-866-915 9.6/55/200 kbps
ScanSeries
ChannelCfg
ChannelQueue
Auth.Security
CryptoTables
FileEncrypt.
NWLSecurity
AES128
APPLICATIONLAYERPROTOCOL
Structureddata§ Everythingisafile(sensor values,
systemconfiguration,encryptionkeys...)
§ Anyapplicationaction,dataexchangemethodorprotocolismappedexclusively ontomanipulationofStructuredDataElements(D7AFiles) andtheirproperties.
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EVERYTHINGISAFILE
ALPALP is a generic API for manipulating D7A files. The interface can be D7A, but also UART, BTLEALP commands are composed of ALP ActionsActions can be read, write, create, delete, execute, condition (query), grant permission, etc...Local or OTA
QUERIES+ACTIONS+D7A
=
DISTRIBUTEDDATABASE
CommunicationModel
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PullToobtaintagsensordataTosetactuatordata
Unsollicited– TagTalkFirstForalarmsandperiodicdata
• PollingdatausingD7APAdvertisingProtocol• PushingdatausingD7APActionProtocol• Dormantsessions (waitforthetagtotalkfirst)
COMMUNICATIONSCHEMES
• Advertisementprotocol• Gatewayqueriesendpoints• Lowpowerwake—up
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D7AADVP
COMMUNICATIONSCHEMES
• Actionprotocol• Notification/tag-talks-first• ALPcommandpreregisteredonendnodes• Filesystem canbeconfigured toactivateALPcommandupon fileaccess
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D7AACTP
COMMUNICATIONSCHEMES
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D7AACTP – APPLICATIONEXAMPLE
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HumidityNotification
Sendamessageto0x23BEwiththehumidityandthebatterylevelwhenthehumiditychanges.
BatteryAlarm
Broadcastbatteryalarmwhenbatterybelow20%andsendalllatestsensorvalues.
SensoronPresence
Whenthepresenceisdetectionfromamobiledeviceandtemperatureisbelow21°C, send‘on’commandtolocalheating.
COMMUNICATIONSCHEMES
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D7AACTP- IMPLEMENTATIONINAPPLICATIONFIRMWARE
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HumidityNotification
MeasurehumidityatxsecintervalandwritevaluetofilewithID0x34
BatteryAlarm
MeasurebatteryatxsecintervalandwritevaluetofilewithID0x25
SensoronPresence
MeasuretemperatureatxsecintervalandwritevaluetofilewithID0x33
COMMUNICATIONSCHEMES
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D7AACTP- CONFIGURATIONOFFILESYSTEM
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HumidityNotification
Configurenotificationheader forfile0x34andsetquerytoconditiondifferentfrompreviousvalue.Set0X23BEand0x34innotificationfile.
BatteryAlarm
Configurenotificationheader forfile0x25andsetquerytocondition<20.Set0x25,0x34and0x33 innotificationfile.
SensoronPresence
Configurenotificationon file0x19(localisationfile)andset0x33 ininthenotificationfile.
COMMUNICATIONSCHEMES
D7AActPIdealforperiodic sensordatatransmissionorsensortriggered
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TRADE-OFFS
D7AAdvPIdealforad-hocdatagathering,notforperiodicorsensortriggered.
Tradeoffbetweenenergyconsumptionandlatency
• Dormantsessions• Usecasespecific,combinationspossible• Networkbehaviorover-the-airupdatable
CONTEXTAWARESENSORANDACTUATORDATAPROPAGATION
Writeandreadfromfiles
Configuresystemthroughconfigurationfiles
Configuredthrough filesystem
Handlesscheduledscancycles
Handlesqueriesfromotherdevices
Handlesqueriesandnotificationson filechanges
Filesystemconfigurableovertheair
THEMATCH
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FREQUENCY
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DATARATEó RX/TXDURATIONVSRANGE
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100bps -156dBm 12 bytes payload 6 seconds
250bps -10kbps
-155dBm max payload 50 bytes 50 ms – 2 seconds
9.6 kbps55 kbps166 kbps
-105dBm max payload 256 bytes 10 ms
RX SCHEDULING
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RX_DELAY_1
RX_DELAY_2
TX RX1 RX2
RECEIVER INITIATED TRANSMISSION
TX RX
ASYNCHRONOUS WITH LOCAL SYNCHRONIZATION
SCHEDULED_PERIOD
TX RX RX RX
SCHEDULED_PERIOD
COORDINATOR SAMPLED LISTENING USING BEACONS
TXTX RX RX
PERMANENT RX
WIRELESSTRADE-OFFSAPPLIEDTOLPWAN
$$$ Today– nolicensedLPWANsolutiondeployedyet
Lowerfrequencybands(withlessbandwidth)
Simplecoding,i.e.lowerdatarates(→lowcomplexity,lowcost)
Limit‘radioontime’(sleep,lowdatausage,downlinkafteruplink)
Predominantlystartopologies(lowinstallation&maintenancecost)
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WHEN ONERFTECHNOLOGYISNOTENOUGH
LPWANCOMPETITION BETWEEN STANDARDS?
Yes, but room for multiple LPWAN technologies!
Device and connectivity
requirements
Source: Ericsson
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Source: Actility
LPWAN- USECASESUSE CASES INVOLVINGLOW DATA RATE, BATTERY-OPERATED DEVICES, LOW SENSOR DENSITY
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LPWANFORECAST> 2.5 BILLION LPWAN CONNECTIONS BY END OF 2024*
*CAVEAT: Many other numbers circulateSource: Machina Research
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WHEREDASH7MEETSLPWAN
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LPWANOPEX
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Theytellyou or devicesareCHEAP!
NoneofthesetechnologiesallowstoupgradefirmwareovertheairWhatif:
- asecuritybreachisfound- SigFox goesbankrupt- Anewbuildingmasksthenearestantennaandyouloosecoverage- Youfindanalgorithmtoreducepowerandgain1yearofbatterylife
MostofthesedeviceswillbedeployedforYEARS!
SECURETHEFUTURE
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or hardwareiscompatiblewith
AddaDASH7stackandUpgradeFirmwareOverTheAirto• SwitchConnectivity• Re-ConfigureDevicesRemotely• Applysecuritypatches• SwitchbetweenPublicandPrivateNetwork
AvoidcostlyMaintenance
WHENACTIVERFIDMEETSPASSIVERFID
APPLICATIONLAYERPROTOCOL(ALP)
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ALPALP is a generic API for manipulating D7A files. The interface can be D7A, but also UART, BTLEALP commands are composed of ALP ActionsActions can be read, write, create, delete, execute, condition (query), grant permission, etc...Local or OTA
Structureddata§ Everythingisafile(sensor values,
systemconfiguration,encryptionkeys...)
§ Anyapplicationaction,dataexchangemethodorprotocolismappedexclusively ontomanipulationofStructuredDataElements(D7AFiles) andtheirproperties.
Everything isafile
PROVISIONING,DEPLOYMENT,OPERATION
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Longrangeisgreatbutsometimesyouwantto:- Knowwhichdeviceisinyourhand- Triggersomethingonthedeviceinfrontofyou- Distributekeyswithout beingoverheard
ALP over
UHFGEN-2
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UHFEPCGEN-2
DASH7
Sigfox
0.5-10m
1– 30km
10– 2000m
100bps
10– 166kbps
40– 600kbps
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HOWTOCHOOSETHERIGHTPROTOCOL?
• Coverage?• Local• National• Worldwide
• Time to market?• Outdoor, indoor,
deep indoor?• Security?• Business model?• Scalability/capacity?
• Vendor lock-in?
• Minimum viable lifetime?
• Device size and antenna design?
• Firmware updates needed (OTA)?
• Module or embedded chipset?
• Static or mobile device?
• Addressing?
• What is the size of data to send?
• What is the periodicity of transmissions?
• How critical is the data (reliability)?
• Downlink versus uplink communication?
Your application Your device Your dataSome questions to ask
PUBLIC
OpenStandard
VeryLowPower
SecurityPrivacy
LargeNumberOfNodes
LowBitrate
LowCost
LongRange