Technologies, Beaconing, and Routing in Vehicular...

75
Michele Segata, Renato Lo Cigno - University of Trento with special thanks to Falko Dressler, Christoph Sommer, Bastian Bloessl, Stefan Joerer, David Eckhoff Wireless Mesh and Vehicular Networks Technologies, Beaconing, and Routing in Vehicular Networks

Transcript of Technologies, Beaconing, and Routing in Vehicular...

Page 1: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

MicheleSegata,RenatoLoCigno - UniversityofTrento

withspecialthankstoFalko Dressler,ChristophSommer,BastianBloessl,Stefan Joerer,DavidEckhoff

WirelessMeshandVehicularNetworks

Technologies,Beaconing,andRoutinginVehicularNetworks

Page 2: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Motivation

• TaxonomyofUseCases

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 2

Vehicle-to-X

Non-Safety

Comfort

ContextualInformation Entertainment

TrafficInformationSystems

OptimalSpeedAdvisory

Congestion,Accident

Information

Safety

SituationAwareness

AdaptiveCruiseControl

BlindSpotWarning

WarningMessages

TrafficLightViolation

ElectronicBrakeLight

Page 3: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Technology

• Communicationparadigmsandmedia

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 3

[1] Dar, K. and Bakhouya, M. and Gaber, J. and Wack, M. and Lorenz, P., "Wireless Communication Technologies for ITS Applications," IEEE Communications Magazine, vol. 48 (5), pp. 156-162, May 2010

WirelessCommunicationTechnologies

Infrastructure-based

Broadcast

FMRadio,DAB/DVB,

Cellular

GSM

2GCellular

UMTS

3GCellular

LTE/WiMAX

4GCell.

Infrastructureless

ShortRange

Millimeter,Infrared,Visible

802.15.1Bluetooth

802.15.4ZigBee

MediumRange

802.11Wi-Fi

DSRC/WAVE

Page 4: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Anoutline

A(rough)outlineoftheVehicularNetworkstopics• Application:whyVN?• Communication:technologies,alternatives,protocols,challenges• Simulation: evaluatingvehicularnetworkswithoutvehiclesand

withoutnetworks.Toolsandmodels

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 4

Page 5: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

COMMUNICATIONTECHNOLOGIES(Someofthem)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 5

Page 6: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• Concept– Divideworldintocells,eachservedbybasestation– Allows,e.g.,frequencyreuseinFDMA

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 6

f0

f1

f2

f0f2

f1

f2

f0

f1

f0

f1

f2

f0

f1

f2

f0

f1

f2

f0f2

f0f2

f0f2

f0

f1

f2

f0

Page 7: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• Stricthierarchyofnetworkcomponents

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 7

UE

Core Network

RNC

Cell

NodeB

Cell Cell Cell Cell

NodeB

Cell

RNC

Cell

NodeB

Cell Cell Cell Cell

NodeB

Cell

Page 8: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• CanUMTSsupportCar-to-Xcommunication?– Ex:UTRAFDDRelease99(W-CDMA)– Speedofvehiclesnotalimitingfactor

• Fieldoperationaltestsat290km/hshowsignaldropsonlyaftersuddenbraking(⇨ handoverpredictionfailures)

– Openquestions• Delay• Capacity

• ChannelsinUMTS– Sharedchannels

• E.g.,RandomAccessChannel(RACH),uplinkandForwardAccessChannel(FACH),downlink

– Dedicatedchannels• E.g.,DedicatedTransportChannel(DCH),up-/downlink

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 8

Page 9: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• FACH– Timeslotsmanagedbybasestation– Delayontheorderof10ms per40ByteandUE– Capacityseverelylimited(innon-multicastnetworks)– NeedtoknowcurrentcellofUE

• RACH– SlottedALOHA– randomaccessbyUEs

• PowerrampingwithAcquisitionIndication– Delayapprox.50ms

per60ByteandUE– Massiveinterference

withotherUEs

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 9

Page 10: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• DCH– Delay:approx.250ms /2s/10sforchannelestablishment

• Dependsonhowfine-grainedUEpositionisknown– MaintainingaDCHisexpensive

• Closed-LoopPowerControl(nointerferenceofotherUEs)• Handoverbetweencells

– Upperlimitofapprox.100UEs

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 10

Page 11: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Cellularnetworks

• So:canUMTSsupportCar-to-Xcommunication?– Atlowmarketpenetration:yes– Eventually:

• Needtoinvestinmuchsmallercells(e.g.,alongfreeways)• Needtoimplementmulticastfunctionality(MBMS)

– MainusecaseforUMTS:centralizedservices• Ex.:GoogleMapsTraffic

– CollectinformationfromUMTSdevices– Storageofdataoncentralserver– DisseminationviaInternet(⇨ idealforcellularnetworks)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 11

Page 12: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p

• IEEE802.11{a,b,g,n,ac}forCar-to-Xcommunication?– Can’tbeininfrastructuremodeand

adhocmodeatthesametime– Switchingtimeconsuming– Associationtimeconsuming– Nointegralwithin-networksecurity– (Massively)shared

spectrum(⇨ ISM)– NointegralQoS– Multi-patheffects

reducerangeandspeed

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 12

[1]FayHui,Prasant Mohapatra.„ExperimentalCharacterizationofMultihop CommunicationsinVehicularAdHocNetwork“.InProceedingsofthe2ndACMinternationalworkshoponVehicularadhocnetworks,2005

Page 13: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p

• Newlowerlayersfor“WirelessAccessinVehicularEnvironments”(WAVE)– PHYlayermostlyidenticaltoIEEE802.11a

• VariantwithOFDMand16QAM• Higherdemandsontolerances• Reductionofintersymbolinterference

becauseofmulti-patheffects– Doubletimingparameters– Channelbandwidthdownto10MHz(from20MHz)– Throughputdownto3...27Mbit/s(from6...54Mbit/s)– Rangeupto1000m,speedupto200km/h

– MAClayerofIEEE802.11aplusextensions• RandomMACAddress• QoS (EDCApriorityaccess,cf.IEEE802.11e,...)• Multi-FrequencyandMulti-Radiocapabilities• NewAdHocmode• ...

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 13

Page 14: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p- OFDMSignal

• Howdoesitlooklike?

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 14

Page 15: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p

• ClassicIEEE802.11BasicServiceSet(BSS)– Dividesnetworksintologicalunits

• Nodesbelongto(exactlyone)BSS• PacketscontainBSSID• Nodesignorepacketsfrom“foreign”BSSs• Exception:Wildcard-BSSID(-1)forprobes• Adhocnetworksemulateinfrastructuremode

– JoiningaBSS• AccessPointsendsbeacon• Authenticationdialogue• Associationdialogue• NodehasjoinedBSS

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks15

BSSSSID “A”

BSSSSID “B”

BSSSSID “C”

Page 16: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p

• New:802.11OCBMode(OutsideoftheContextofaBSS)– DefaultmodeofnodesinWAVE– NodesmayalwaysuseWildcardBSSinpackets– NodeswillalwaysreceiveWildcardBSSpackets– MayjoinBSSandstilluseWildcardBSS

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 16

BSSSSID “A”

BSSSSID “B”

Page 17: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE802.11p- MAC

• IEEE802.11HybridCoordinationFunction(HCF)– cf.IEEE802.11eEDCA– DIFS⇨ AIFS(ArbitrationInter-FrameSpace)

• DCF⇨ EDCA(EnhancedDistributedChannelAccess)

– Classifyuserdatainto4ACs(AccessCategories)• AC0(lowestpriority)• …• AC3(highestpriority)

– EachACshasdifferent...• CWmin,CWmax,AIFS,TXOPlimit(max.continuoustransmissions)

– ManagementdatausesDIFS(notAIFS)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 17

Page 18: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 18

• Map8userpriorities⇨ 4accesscategories⇨ 4queues• Queuescompeteindependentlyformediumaccess

IEEE802.11p

AC0

AC1

AC2

AC3

virt

ual c

ollis

ion

Page 19: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 19

• Parameterization

• Samplequeueconfiguration

IEEE802.11p

Parameter Value

SlotTime 13µs

SIFS 32µs

CWmin 15

CWmax 1023

Bandwidth 3..27mbit/s

Parameter AC_BK AC_BE AC_VI AC_VO

CWmin CWmin CWmin (CWmin+1)/2-1 (CWmin+1)/4-1

CWmax CWmax CWmax CWmin (CWmin+1)/2-1

AIFSn 9 6 3 2

Page 20: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

AC_VO AC_VI AC_BE AC_BK

ChannelAccess

Backoff:0 0 0 0

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 20

Page 21: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

AC_VO AC_VI AC_BE AC_BK

Backoff:0 0 0 0

Channelbusy?

StartContention

WaitforIdle

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 21

ChannelAccess

Page 22: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

AC_VO AC_VI AC_BE AC_BK

0 0 0

Backoff0?

WaitAIFS(SIFS+AIFSn *Slotlen)

Waitforbackoff=0

Backoff:0

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 22

ChannelAccess

Page 23: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Backoff:0

AC_VO AC_VI AC_BE AC_BK

Backoff:2 0 0 0

TransmissionOver

PostTransmitBackoff

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 23

ChannelAccess

Page 24: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

2

AC_VO AC_VI AC_BE AC_BK

Backoff:2 0 0 0

AC_VIQueuereadytosend…waitAIFS Backoff

Ch becomesbusy

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 24

ChannelAccess

Page 25: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Backoff:2 21

AC_VO AC_VI AC_BE AC_BK

Backoff:1 0 0Channelidle

Channelbusy

[Slottimepassed]/DecrementBackoff

Channelstatechanges

Backoff:0 0

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 25

ChannelAccess

Page 26: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

3Backoff:0 0

AC_VO AC_VI AC_BE AC_BK

0 0

Queuereadytosend

InternalContentionBackoff

Higherprio

rity

queu

eready

IEEE802.11p

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 26

ChannelAccess

Page 27: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 27

• QoSinWAVE– meanwaitingtimeforchannelaccess,givensampleconfiguration(and

TXOPLimit=0⇨ singlepacket)

IEEE802.11p

[1]Eichler,S.,"PerformanceevaluationoftheIEEE802.11pWAVEcommunicationstandard,"Proceedingsof66thIEEEVehicularTechnology Conference(VTC2007-Fall),Baltimore,USA,October2007,pp.2199-2203

AC CWmin CWmax AIFS TXOP tw (inμs)

0 15 1023 9 0 264

1 7 15 6 0 152

2 3 7 3 0 72

3 3 7 2 0 56

n Single Node: n Multiple Nodes:

Page 28: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 28

• ProsofUMTS/LTE– Easyprovisionofcentralizedservices– Quickdisseminationofinformationinwholenetwork– Pre-deployedinfrastructure– Easymigrationto(andintegrationinto)smartphones

• ConsofUMTS/LTE– Highshortrangelatencies(mightbetoohighforsafety)– Networkneedsfurtherupgrades(smallercells,multicastservice)– Highdependenceonnetworkoperator– Highloadincorenetwork,evenforlocalcommunication

UMTS/LTEvs.IEEE802.11p

Page 29: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

UMTS/LTEvs.IEEE802.11p

• Prosof802.11p/Adhoc– Smallestpossiblelatency– Cansustainoperationwithoutnetworkoperator/provider– Networkloadhighlylocalized– Betterprivacy(⇨ laterslides)

• Consof802.11p/Adhoc– Needsgatewayforprovisionofcentralservices(e.g.,RSU)– Nopre-deployedhardware,andhardwareisstillexpensive

• Thesolution?– hybridsystems:

deploybothtechnologiestovehiclesandroad,decidedependingonapplicationandinfrastructureavailability

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 29

Page 30: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

HIGHERLAYERPROTOCOLS

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 30

Page 31: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

HigherLayerStandardsforIEEE802.11p

• Channelmanagement– Dedicatedfrequencybandat5.9GHzallocatedtoWAVE

• ExclusiveforV2VundV2Icommunication• Nolicensecost,butstrictrules• 1999:FCCreserves7channelsof10MHz(“U.S.DSRC”)

– 2reservedchannels,1+4channelsforapplications• ETSIEuropereserves5channelsof10MHz

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 31

[1]ETSIES202663V1.1.0(2010-01):IntelligentTransportSystems(ITS);EuropeanprofilestandardforthephysicalandmediumaccesscontrollayerofIntelligentTransportSystemsoperatinginthe5GHzfrequencyband

CriticalSafety of

Life

ch1725.860GHz

SCH

ch1745.870GHz

SCH

ch1765.880GHz

ControlChannel(CCH)

ch1785.890GHz

SCH

ch1805.900GHz

SCH

ch1825.910GHz

Hi-PowerPublicSafety

ch1845.920GHz

SCH

ch1725.860GHz

SCH

ch1745.870GHz

SCH

ch1765.880GHz

SCH

ch1785.890GHz

CCH

ch1805.900GHz

Page 32: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

HigherLayerStandardsforIEEE802.11p

• Needforhigherlayerstandards– Unifiedmessageformat– Unifiedinterfacestoapplicationlayer

• U.S.– IEEE1609.*– WAVE(“WirelessAccessinVehicularEnvironments“)

• Europe– ETSI– ITSG5(“IntelligentTransportationSystems”)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 32

Page 33: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE1609

• IEEE1609.*upperlayers(buildingonIEEE802.11p)– IEEE1609.1:“Operatingsystem”– IEEE1609.2:Security– IEEE 1609.3:Networkservices– IEEE1609.4:Channelmgmt.

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 33

[1]Jiang,D.andDelgrossi,L.,"IEEE802.11p:Towardsaninternationalstandardforwirelessaccessinvehicularenvironments,"Proceedingsof67thIEEEVehicularTechnologyConference(VTC2008-Spring),MarinaBay,Singapore,May2008[2]Uzcátegui,RobertoA.andAcosta-Marum,Guillermo,"WAVE:ATutorial,"IEEECommunicationsMagazine,vol.47(5),pp.126-133,May2009

TCP/UDP

WAVEPHY

ChannelCoordination,WAVEMAC

IPv6WSMP

Managem

ent

Security LLC

802.

11p 16

09.

4

1609

.3

1609

.2

WAVEPHY

Page 34: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE1609

• Channelmanagement– WAVEallowsforbothsingleradiodevices&multiradiodevices– DedicatedControlChannel(CCH)formgmtandsafetymessages⇨ singleradiodevicesneedtoperiodicallylistentoCCH

– Timeslots• SynchronizationenvisionedviaGPSreceiverclock• Standardvalue:100mssyncinterval(with50msonCCH)• Shortguardintervalatstartoftimeslot

– Duringguard,mediumisconsideredbusy(⇨ backoff)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 34

[1]IEEEVehicularTechnologySociety,"IEEE1609.4(Multi-channelOperation),"IEEEStd,November,2006

CCHinterval

CCHinterval

“SCH”interval

“SCH”interval

t = n × 1s

Page 35: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE1609

• Packettransmission– SortintoACqueue,basedonWSMP(orIPv6)EtherTypefield,destination

channel,anduserpriority– Switchtodesiredchannel,setupPHYpoweranddatarate– Startmediumaccess

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 35

CC

HSC

HAC0AC1AC2AC3 vi

rt. C

ollis

ion

AC0AC1AC2AC3 vi

rt. C

ollis

ion

Cha

nnel

Rou

ter

Cha

nnel

sel

ectio

n an

d se

tup

Cha

nnel

acc

ess

Page 36: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE1609

• Channelmanagement– ControlChannel(CCH):

• Defaultchanneluponinitialization• WAVEserviceadvertisements(WSA),WAVEshortmessages(WSM)

• Channelparameterstakefixedvalues

– ServiceChannel(SCH):• OnlyafterjoiningWAVEBSS• WAVEshortmessages(WSM),IPdatatraffic(IPv6)

• Channelparameterscanbechangedasneeded

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 36

Page 37: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

IEEE1609

• WAVEserviceadvertisement(WSA)– BroadcastonControlChannel(CCH)– IdentifiesWAVEBSSsonServiceChannels(SCHs)– Canbesentatarbitrarytimes,byarbitrarynodes– OnlypossibilitytomakeothersawareofdatabeingsentonSCHs,aswellas

therequiredchannelparameterstodecodethem

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 37

NodeA NodeB

Page 38: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

ETSIITSG5

• Motivation– EuropeanstandardizationeffortbasedonIEEE802.11p– StandardizationtoincludelessonslearnedfromWAVE– Differentinstrumentationoflowerlayers– Differentupperlayerprotocols– Differentchannelassignment

• ITS-G5A(safety)• IST-G5B(nonsafety)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 38

Page 39: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

ETSIITSG5

• Protocolstack– PHYandMACbasedonIEEE802.11p– Mostprominentchange:

crosslayerDecentralizedCongestionControl(DCC)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 39

Page 40: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

ETSIITSG5

• Channelmanagement– Multiradio,multiantennasystem

• Noalternatingaccess⇨ Circumventsproblemswithsynchronization⇨ Noreductioningoodput

• DirectresultofexperienceswithWAVE

– OneradiotunedtoCCH• ServiceAnnouncementMessage(SAM)• Periodic:CooperativeAwarenessMessages(CAM)• Eventbased:DecentralizedEnvironmentNotificationMessage(DENM)

– Addl.radiotunedtoSCH• Userdata

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 40

Page 41: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

ETSIITSG5

• CooperativeAwarenessMessage– Periodic(upto10Hz)safetymessage– Informationonstateofsurroundingvehicles:

• Speed,location,…– Messageagehighlyrelevantforsafety

• Needmechanismstodiscardoldmessages– SafetyapplicationsrelyonCAMs:

• Tailendofjam• Rearendcollision• Intersectionassistance…

– SentonCCH– Generatedevery100ms..1s,butonlyif

∆angle(>4°),∆position(>5m),∆speed(>1m/s)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 41

Page 42: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

ETSIITSG5

• DecentralizedEnvironmentalNotificationMessage(DENM)– Eventtriggered(e.g.,byvehiclesensors)

• Hardbraking• Accident• Tailendofjam• Constructionwork• Collisionimminent• Lowvisibility,highwind,icyroad,…

– Messageshave(tight)localscope,relaybasedon• Area(definedbycircle/ellipse/rectangle)• Roadtopology• Drivingdirection

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 42

Page 43: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

BEACONING:1-HOPBROADCAST

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 43

Page 44: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Beaconing:1-hopBroadcast

• ETSIITSCAMs(CooperativeAwarenessMessages)– Periodic(upto10Hz)safetymessage– Informationonstateofsurroundingvehicles:

• Speed,location,…– Messageagehighlyrelevantforsafety

• Needmechanismstodiscardoldmessages

• IEEE1609BSMs(BasicSafetyMessages)

• …but

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 44

Page 45: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Beaconing:1-hopBroadcast

• Openissues– Infrastructure-lessoperation:needshighmarkedpenetration– Required/tolerablebeaconintervalhighlydependentonscenario– Designneedsdedicatedchannelcapacity

• Realnetworksareheterogeneous– Roadsideinfrastructurepresentvs.absent– Freewayscenariovs.innercity– Ownprotocol⇔ other,future,andlegacyprotocols

• Howtodobetter?– Dynamicallyadaptbeaconinterval– Dynamicallyuseallfree(!)channelcapacity

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 45

Page 46: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DecentralizedCongestionControl(DCC)

• CorefeatureofETSIITSG5• Adaptiveparameterizationtoavoidoverload• ConfigurableparametersperAC:

– TXpower(TransmitPowerControl,TPC)– Minimumpacketinterval(TransmitRateControl,TRC)– Datarate(TransmitDatarateControl,TDC)– SensitivityofClearChannelAssessment(DCCSensitivityControl,DSC)

• Statemachinedetermineswhichparametersetisselected;availablestates:– Relaxed– Active(multiplesubstates)– Restrictive

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 46

Page 47: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DecentralizedCongestionControl(DCC)

• Measuremin/maxChannelLoad(x)– Min/maxchannelloadin [tnow-x..tnow]– Channelload:fractionoftimethatchannelwassensedbusyduring

measuringinterval(ex:𝑇m ≈ 1s)– Channelbusy:Averagereceivedpower(signalornoise)duringprobing

interval(ex:𝑇p ≈ 10μs)abovecarriersensethreshold

• StatemachineforControlChannel:

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 47

Page 48: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DecentralizedCongestionControl(DCC)

• Example:ControlChannel– TXpower:relaxed:33dBm ⇨ active:ref⇨ restrictive:-10dBm– “ref”:Valueremainsunchanged– Remember:

• 33dBm ⇨ 10%.% mW⇨ 2000mW• -10dBm ⇨ 10'( mW ⇨ 0.1mW

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 48

StateRelaxed Active Restrictive

AC_VI AC_VO AC_BE AC_BK

TXpower 33dBm ref 25dBm 20dBm 15dBm -10dBm

Minpkt interval 0.04s ref ref ref ref 1s

Datarate 3Mbit/s ref ref ref ref 12Mbit/s

CCAthreshold -95 dBm ref ref ref ref -65 dBm

Page 49: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DecentralizedCongestionControl(DCC)

• Oscillatingchannelload(bothlocalandglobal!)– …causedbychannelaccessbeingtoorestrictive(standardparameters)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 49

[1]DavidEckhoff,Nikoletta Sofra andReinhardGerman,"APerformanceStudyofCooperativeAwarenessinETSIITSG5andIEEEWAVE,"Proceedingsof10thIEEE/IFIPConferenceonWirelessOndemandNetworkSystemsandServices(WONS2013),Banff,Canada,March2013.

Page 50: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DynB– DynamicBeaconing

• Consideralltheradioshadowingeffectstoadaptveryquicklytothecurrentchannelquality

• Mainidea:continuouslyobservetheloadofthewirelesschanneltocalculatethecurrentbeaconinterval𝐼

• Basecalculationof𝐼 on:– Channelbusytimefraction𝑏+– Numberofneighbors𝑁– Desiredinterval𝐼-./– Desiredchannelbusytimefraction𝑏-./

• 𝐼 = 𝐼-./ + 𝑟× 𝐼456 − 𝐼-./– With𝐼456 = 𝑁 + 1 ×𝐼-./

andr=(bt /bdes)- 1clippedin[0,1]

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 50

[1]ChristophSommer,StefanJoerer,MicheleSegata,OzanK.Tonguz,RenatoLoCignoandFalkoDressler,"HowShadowingHurts VehicularCommunicationsandHowDynamicBeaconingCanHelp,"Proceedingsof32ndIEEEConferenceonComputerCommunications(INFOCOM2013),Mini-Conference, Turin,Italy,April2013

Page 51: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

DynB– DynamicBeaconing

• wrt.handlingdynamicsintheenvironment– Assumingtwolargerclustersofvehiclesmeetingspontaneously(e.g.,at

intersectionsinsuburbanorwhentwobigtrucksleavethefreeway)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 51

Page 52: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Application-based:JerkBeaconing

• Jerk:– physicalquantitymeasuringvariationofaccelerationovertime

– usinganestimationofjerkwecomputethebeaconinterval

– tunableparameters:• minimumbeaconinterval• maximumbeaconinterval• sensitivity

• Mainidea:– themoreconstantthesystem,thelowertherequirement– sendupdatesonlywhenneeded,usepredictionotherwise

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 52

Page 53: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

JerkBeaconing

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 53

Page 54: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Evaluation:Strongshockwaves

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 54

3m

45 %

4m

17%

Page 55: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Evaluation:Moderateshockwaves

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 55

4.5m

40%

4.5m

10%

Page 56: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

MULTI-HOPFORWARDINGRoutingtechniquesinVehicularNetworks

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 56

Page 57: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Classicalrouting

• MightnotbesuitedforVehicularNetworks…– Distancevector

• Eachnodestoresavectorof(dst,cost,next-hop)– Linkstate

• Knowntopology+Dijkstra• Fastconvergencevs.overhead

– Reactive(ondemand)• Establishroutesonlywhenneeded

– Proactive(tabledriven)• Continuouslymaintainroutesuptodate

– Hopbyhop• Intermediatenodeschosethenexthopforapacket

– Sourcerouting• Packetsincludethefullroute

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 57

Page 58: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Georouting

• Primarymetrics:position/distancetodestination• Requiresnodepositionstobeknown(atleastforthedestination)• Twooperationmodes(typ.):

– Greedymode:choosenexthopaccordingtomaxprogress– Recoverymode:escapedeadends(localmaxima)

• Mustensurethatmessagenevergetslost

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 58

Page 59: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Routing

• Q:Can(classical)routingworkinVANETs?• A:Onlyinsomecases.• Commonlyneedmulticastcommunication,lowload,lowdelay• Additionalchallengesandopportunities:

networkpartitioning,dynamictopology,complexmobility,…

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 59

[1]Toor,YasserandMühlethaler,PaulandLaouiti,Anis andFortelle,ArnauddeLa,"VehicleAdHocNetworks:ApplicationsandRelatedTechnicalIssues,"IEEECommunicationsSurveysandTutorials,vol.10(3),pp.74-88,2008

Car-to-X

Non-Safety

Comfort

ContextualInformation Entertainment

TrafficInformationSystems

OptimalSpeedAdvisory

Congestion,Accident

Information

Safety

SituationAwareness

AdaptiveCruiseControl

BlindSpotWarning

WarningMessages

TrafficLightViolation

ElectronicBreakLight

Page 60: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

<!><!>

<!>

<!>

<!>

<!>

<!>

<!>

idle send

rcvdup

“Smart”Flooding

• Flooding:Multi-HopBroadcast• Simplestprotocol:“SmartFlooding“:

– Problem:BroadcastStorm• Superfluousre-broadcastsoverloadchannel

60Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks

Page 61: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Broadcastsuppression

• Motivation– Needsnoneighborinformation– Needsnocontrolmessages– Maximizesdistanceperhop– Minimizespacketloss

• Approach– Nodereceivesmessage,estimatesdistancetosender– Selectivelysuppressesre-broadcastofmessage– Alternatives

• weightedp-persistence• slotted1-persistence• slottedp-persistence

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 61

[1]Wisitpongphan,Nawaporn andTonguz,OzanK.andParikh,J.S.andMudalige,Priyantha andBai,FanandSadekar,Varsha,"BroadcastStormMitigationTechniquesinVehicularAdHocNetworks,"IEEEWirelessCommunications,vol.14(6),pp.84-94,December2007

Page 62: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Broadcastsuppression

• Estimatedistancetosenderas0≤ρij ≤1

• GPSbased

• RSSbased

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 62

Page 63: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Broadcastsuppression

• Weightedp-persistence– Probabilisticfloodingwithvariablepij forre-broadcast– Thus,higherprobabilityforlargerdistanceperhop

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 63

pij

Page 64: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Broadcastsuppression

• Weightedp-persistence– WaitWAIT_TIME(e.g.,2ms)– choosep=min(ρij)ofallreceivedpackets

(probabilityforre-broadcastofpacket)– Ensurethatatleastoneneighborhasre-broadcastpacket

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 64

idle wait 2 msrcv

dup

sendp

wait δ ms

¬p

dup expired

dup

Page 65: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:BroadcastSuppression

• Slotted1-persistence– Suppressionbasedonwaitingandoverhearing– Dividelengthofroadintoslots– Moredistantslotssendsooner– Closerslotssendlater(orifmoredistantslotsdidnotre-broadcast)– Thus,higherprobabilitytotransmitoverlongerdistance

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 65

pij

t=0 t=τ t=2τ t=3τ

Page 66: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:BroadcastSuppression

• Slotted1-persistence– Divide“communicationrange“intoNsslotsoflengthτ– Nodeswaitbeforere-broadcast,waitingtimedependingonslot– Duplicateeliminationtakescareofsuppressionofbroadcasts

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 66

idle wait Tijrcv

dup

send¬dup

dup

Page 67: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:BroadcastSuppression

• Slottedp-persistence– Cf.slotted1-persistence– Fixedforwardingprobabilityp(insteadof1)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 67

pij

t=0 t=τ t=2τ t=3τ

Page 68: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:BroadcastSuppression

• Slottedp-persistence– WaitforTij (insteadoffixedWAIT_TIME)– Useprobabilityp(insteadof1)– Ensurethatatleastoneneighborhasre-broadcastthepacket

bywaitingforδ’>max(Tij)

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 68

idle wait Tijrcv

dup

sendp

wait δ’

¬p

dup expireddup

Page 69: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Remainingproblems

• Temporarynetworkfragmentation

• Undirectedmessagedissemination

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 69

Page 70: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding+X:DV-CAST

• Idea:detectcurrentscenario,switchbetweenprotocols• Checkforfragmentednetwork

– Networkconnectedà performbroadcastsuppression

– Networkfragmentedà performStore-Carry-Forward

70

<!>

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks

[1] Tonguz, Ozan K. and Wisitpongphan, N. and Bai, F., "DV-CAST: A distributed vehicular broadcast protocol for vehicular ad hoc networks," IEEE Wireless Communications, vol. 17 (2), pp. 47-57, April 2010

Page 71: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Remainingproblems

• Temporarynetworkfragmentation

• Undirectedmessagedissemination

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 71

Page 72: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Geocast:TO-GO

• Step1:Findbestnexthop(TargetNode,T)– FindN:Furthestneighbortowardsdestination– FindJ:Furthestneighbortowardsdestination,currentlyonjunction– FindNJ:Furthestneighbortowardsdestination,asseenbyJ– ifN,NJ areonthesameroad,

pickNelse,pickJ

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 72

N

NJ

J

Page 73: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Geocast:TO-GO

• Step2:FindForwardingSet(FS)– NodesintheFSwillcompeteforrelayingofthemessage– OnlyonenodeinFSshouldrelay

thus,allnodesinFSmustheareachother– FindingoptimalsolutionisNPcomplete– TO-GOusesapproximation

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 73

Page 74: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Geocast:TO-GO

• Step3:MulticastmessagetoallnodesinFS– NodesintheFScompeteforrelayingofthemessage– EnsuremaximumprogresswithinFS– Delayre-broadcastby𝑡– Suppressre-broadcastifanothernodesforwardswithin𝑡– 𝑡 = 𝜏×𝑑;/𝑑456

with:• 𝜏:Maximumdelayperhop• 𝑑;:DistancetoTargetNode• 𝑑456:DistancefromlasthoptoTargetNode

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 74

Page 75: Technologies, Beaconing, and Routing in Vehicular Networksdisi.unitn.it/locigno/teaching-duties/wmvn/aa17-18/... · • New: 802.11 OCB Mode (Outside of the Context of a BSS) –Default

Flooding:Remainingproblems

• Temporarynetworkfragmentation

• Undirectedmessagedissemination

Wireless Mesh & Vehicular Networks - Technologies, Beaconing, and Routing in Vehicular Networks 75