1、BRITISH STANDARD BS EN 12795:2003 Road transport and traffic telematics Dedicated Short Range Communication (DSRC) DSRC data link layer: medium access and logical link control The European Standard EN 12795:2003 has the status of a British Standard ICS 35.100.20; 35.240.60 BS EN 12795:2003 This Brit
2、ish Standard was published under the authority of the Standards Policy and Strategy Committee on 30 May 2003 BSI 30 May 2003 ISBN 0 580 41964 9 National foreword This British Standard is the official English language version of EN 12795:2003. It supersedes DD ENV 12795:1997 which is withdrawn. The U
3、K participation in its preparation was entrusted to Technical Committee EPL/278, Road transport informatics, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement inte
4、rnational or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not pur
5、port to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committ
6、ee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 47
7、and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN12795 March2003 ICS35.100.20;35.240.60 SupersedesENV12795:1997 Englishversion Ro
8、adtransportandtraffictelematicsDedicatedShortRange Communication(DSRC)DSRCdatalinklayer:mediumaccess andlogicallinkcontrol TlmatiquedelacirculationetduTransportroutier CommunicationcourteporteCouchedeliaisonde contrledaccsaumdiaetdecontrlelogiquedeliaison ThisEuropeanStandardwasapprovedbyCENon4Decem
9、ber2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentre
10、ortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodies
11、ofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Hungary,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Slovakia,Spain,Sweden,SwitzerlandandUn ited Kingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG Managemen
12、tCentre:ruedeStassart,36B1050Brussels 2003CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN12795:2003EEN12795:2003(E) 2 Contents page Foreword3 1 Scope 5 2 Normativereferences 7 3 Termsanddefinitions . 7 4 Abbreviationsandvariables. 8 5 Frameformat 1
13、0 6 Addressestablishment . 13 7 MediumAccessControl(MAC)sublayer 15 8 LogicalLinkControlsublayer. .26 AnnexA (normative) Datalinklayerparameters .38 AnnexB (informative) Datalinklayeroverhead.39 AnnexC (informative) EvolutionoftheMACsequencebit.40 AnnexD (informative) Addressestablishment.42 AnnexE
14、(informative) Adeviations. 47EN12795:2003(E) 3 Foreword Thisdocument(EN12795:2003)hasbeenpreparedbyTechnicalCommitteeCENTC278“RoadTransportand TrafficTelematics”,thesecretariatofwhichisheldbyNEN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byen
15、dorsement,atthelatestbySeptember2003,andconflictingnationalstandardsshallbewithdrawnatthe latestbySeptember2003. ThisdocumentsupersedesENV12795:1997. ThedevelopmentofthisstandardwascarriedoutunderEuropeanCommissionMandateM/018. ThisEuropeanStandardformspartofaseriesofEuropeanStandardsdefiningthefram
16、eworkofaDedicatedShort RangeCommunication(DSRC)linkintheRoadTransportandTrafficTelematics(RTTT)environment. ThecommunicationrequirementsofmanyRTTTapplicationscanbefulfilledbyDSRC.TheDSRCstandards enablecompliantcommunicationsystemstoservemultipleRTTTapplicationsinparallel. Thesmallserviceareasandsev
17、ererealtimeconstraintsrequireaspecificprotocolarchitectureleadingtothe reducedprotocolstackshowninFigureA,consistingoftheApplicationLayer,theDataLinkLayer,andthe PhysicalLayer.Sucharchitectureisverycommonforrealtimeenvironments. ThisEuropeanStandardgivesthearchitectureandservicesofferedbytheDSRCData
18、LinkLayer. FigureADSRCprotocolstack ThefollowingsetofEuropeanStandardsfortheDSRClinkisissuedbyCEN: EN12253“DSRCPhysicalLayerusingMicrowaveat5.8GHz”; EN12795“DSRCDataLinkLayer:MACandLLC”(thisEuropeanStandard); EN12834“DSRCApplicationLayer“; EN13372“DSRCProfilesforRTTTApplications“. AnnexAisnormative.
19、AnnexesB,C,DandEareinformative.EN12795:2003(E) 4 AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Hungary,Iceland,Ireland,Italy,Luxembourg
20、,Malta,Netherlands,Norway,Portugal, Slovakia,Spain,Sweden,SwitzerlandandtheUnitedKingdom.EN12795:2003(E) 5 1Scope ThisEuropeanStandard: definestheDataLinkLayerofDSRC; ispositionedwithrespecttootherrelatedstandardsbythelayersdefinedinOSIBasicReferenceModel ENISO/IEC74981asadoptedforDSRC; supportsbroa
21、dcastandhalfduplextransmissionmodes; supportsavarietyoffixedequipmentconfigurations.Itsupportsconfigurationswhereonefixedequipment communicateswithonemobileequipmentunit,aswellasconfigurationswhereonefixedequipmentcan communicatewithseveralmobileequipmentunits; takesintoaccountthatthemobileequipment
22、communicateswiththefixedequipmentwhilepassingthrougha limitedcommunicationzone; definesneitheranyspecificconfigurationnorthelayoutofthecommunicationzone; doesnotdefinetowhatextentdifferentinstancesoffixedequipment,operatinginthevicinityofeachother, needtobesynchronisedwitheachother; definesparameter
23、stobeusedinnegotiationprocedurestakingplacebetweenfixedequipmentandmobile equipment. Bydefiningtwodistinctsublayers,namelythemediumaccesscontrolsublayerandthelogicallinkcontrolsublayer, thisstandarddefines: a) mediumaccesscontrolproceduresforthesharedphysicalmedium; b) addressingrulesandconventions;
24、 c) dataflowcontrolprocedures; d)acknowledgementprocedures; e)errorcontrolprocedures; f) servicesprovidedtoapplicationlayer. TheMACsublayerisspecifictotheDSRC.TheLLCservicesofferedareunacknowledgedandacknowledged connectionlessservicesbasedonISO/IEC88022.EN12795:2003(E) 6 Figure1Architectureanddataf
25、lowoftheDSRCstack Figure1illustratestheglobaldataflowbetweentheelementsoftheDSRCstack,(Physical,DataLinkand ApplicationLayers)andtheapplication. NOTE FordefinitionsofthetermsusedinFigure1seeENISO/IEC74981.EN12795:2003(E) 7 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreferen
26、ce,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedre
27、ferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). ENISO/IEC74981:1995, InformationtechnologyOpenSystemsInterconnectionBasicReference Model:TheBasicModel(ISO/IEC74981:1994). ISO/IEC88022, InformationtechnologyTelecommunicationsandinformationexchangebetweensystems Locala
28、ndmetropolitanareanetworksSpecificrequirementsPart2:Logicallinkcontrol. ISO/IEC3309, InformationtechnologyTelecommunicationsandinformationexchangebetweensystems Highleveldatalinkcontrol(HDLC)proceduresFramestructure. 3 Termsanddefinitions ForthepurposesofthisEuropeanStandard,thefollowingtermsanddefi
29、nitionsapply. 3.1 beaconservicetable datastructuretransmittedbythefixedequipmentindicatingavailableservices 3.2 downlink communicationchannelonwhichthefixedequipmenttransmitsitsinformation 3.3 fixedequipment fixedcommunicationfacilitywithoneormoredownlinkchannelsand,optionally,oneormoreuplinkchannel
30、s NOTE Normallythefixedequipmentisinstalledatafixedlocation,butitmaybeinstalledonamobileplatform. 3.4 linkidentifier uniqueaddressusedforaddressingthemobileequipment 3.5 mobileequipment mobilecommunicationfacilitycapableofreceivinginformationfromthefixedequipmentonthedownlinkand, optionally,alsocapa
31、bleoftransmittinginformationtothefixedequipmentontheuplink NOTE Themobileequipmentnormallycorrespondstothevehiclescommunicationunit. 3.6 profile uniquesetofparametervaluescontrollingthebehaviouroftheDSRCEN12795:2003(E) 8 3.7 serviceaccesspoint interfacepointbetweendatalinklayerandapplicationlayer,th
32、athasauniqueLinkIdentifierandthatallowslayers tocommunicate ENISO/IEC74981:1995 3.8 uplink communicationchannelonwhichmobileequipmenttransmitsitsinformation 3.9 window periodoftimeduringwhichthephysicalmediumisallocatedeithertothefixedequipmentortothemobile equipment 4 Abbreviationsandvariables Fort
33、hepurposesofthisEuropeanStandard,thefollowingabbreviationsandvariablesapply. 4.1Abbreviations 4.1.1 ACK ACKnowledge 4.1.2 Can ACKnowledgedcommand/response 4.1.3 BST BeaconServiceTable 4.1.4 C/R Command/Response 4.1.5 F Final 4.1.6 FCS FrameCheckSequence 4.1.7 FE FixedEquipment 4.1.8 HDLC HighlevelDa
34、taLinkControl 4.1.9 LID LinkIdentifierEN12795:2003(E) 9 4.1.10 LPDU LinklayerProtocolDataUnit 4.1.11 LLC LogicLinkControl 4.1.12 LSB LeastSignificantBit 4.1.13 LSDU LinklayerServiceDataUnit 4.1.14 L1 Layer1ofDSRC(PhysicalLayer) 4.1.15 L2 Layer2ofDSRC(DataLinkLayer) 4.1.16 L7 ApplicationLayerCoreofDS
35、RC 4.1.17 M Modifierfunctionbit 4.1.18 MAC MediumAccessControl 4.1.19 ME MobileEquipment 4.1.20 MSB MostSignificantBit 4.1.21 OBU OnBoardUnit,analternativedescriptortoMobileEquipment 4.1.22 OSI OpenSystemsInterconnection 4.1.23 P Poll 4.1.24 PDU ProtocolDataUnitEN12795:2003(E) 10 4.1.25 P/F Poll/Fin
36、al 4.1.26 R Response 4.1.27 RR ResponseRequest 4.1.28 RSU RoadSideUnit,analternativedescriptortoFixedEquipment 4.1.29 SAP ServiceAccessPoint 4.1.30 UI UnnumberedInformation 4.2Variables 4.2.1 V(RI) receivestatevariable(LLC) 4.2.2 V(SI) transmitstatevariable(LLC) 5Frame format AllDSRCtransmissionsare
37、inframes,andeachframeconformstothestructureshowninFigure2. Flag LinkAddress Field MACControl Field LPDU FrameCheck Sequence Flag Figure2Framestructure FramescontainingnoLPDUformaspecialcase,seeFigure3. Flag LinkAddress Field MACControl Field FrameCheck Sequence Flag Figure3Framestructure,noLPDUEN127
38、95:2003(E) 11 NOTE Thephysicalbitstreamcanalsocompriseapreambleand/oratrailingbits,seeFigure4. Preamble Layer2frame(includingflagsandzerobitinsertionbetweenflags) Optionaltrailing bits Figure4Physicallayerbitstream 5.1Flags Allframesshallstartandendwithaflag.Aflagisazerobitfollowedbysixonebitsfollow
39、edbyazerobit( 0111 1110).Wheninreceivingstate,allstationsshallcontinuouslycheckonabitbybitbasisforthissequence.A transmittershallsendonlycompleteeightbitflags. Theflagwhichendsaframeshallnotbeusedasthestartflagforthenextframe. Inordertoachievetransparencytheflagispreventedfromaccidentallyoccurringin
40、thelinkaddressfield,MAC controlfield,LPDUandframechecksequenceviaazerobitinsertionproceduredescribedin5.7. 5.2 Linkaddressfield ThelinkaddressfieldcarriestheLinkIdentifier(LID).ThelinkaddressfieldshallcontaineitheraprivateLID (containedin4octets),amulticastLID(containedinoneoctet)orabroadcastLID(con
41、tainedinoneoctet).The LSBofeachoctetinthelinkaddressfieldisanextensionbit. 5.2.1 PrivateLID TheprivateLIDisanumberintherangeof0to268435455.ThustheprivateLIDconsistsof28bits.Theprivate LIDisencodedintothelinkaddressfieldasshowninFigure5. XXXXXXX0 XXXXXXX0 XXXXXXX0 XXXXXXX1 76543210 MSB LSB Figure5Pri
42、vatelinkaddressfieldformat TheLSBofthefirstthreeoctetsaresetto0indicatingthatafurtheroctetofthelinkaddressfieldfollows.TheLSB ofthefourthoctetissetto1indicatingthatthisisthelastoctetofthelinkaddressfield. 5.2.2Broadcast LID ThebroadcastLIDequals127.ThusthebroadcastLIDconsistsof7bits.ThebroadcastLIDi
43、sencodedintothe linkaddressfieldasinFigure6.EN12795:2003(E) 12 11111111 76543210 MSB LSB Figure6Broadcastlinkaddressfieldformat TheLSBofthelinkaddressfieldinFigure6issetto1indicatingthatitconsistsofoneoctetonly. 5.2.3Multicast LID ThemulticastLIDisanumberintherangeof0to126.ThusthemulticastLIDconsistsof7bits.ThemulticastLID 0isreservedfortestpurposesandmulticastLIDintherange120to126arereservedforprivateuse.Themulticast LIDisencodedintothelinkaddressfieldasinFigure7. XXXXXXX1 76543210 MSB LSB Xotherthanall 1s Figure7Multicastlinkaddressfieldformat
