1、Oktober 2005DEUTSCHE NORM Normenausschuss Kraftfahrzeuge (FAKRA) im DINPreisgruppe 18DIN Deutsches Institut f r Normung e.V. Jede Art der Vervielf ltigung, auch auszugsweise, nur mit Genehmigung des DIN Deutsches Institut f r Normung e. V., Berlin, gestattet.ICS 35.100.20; 35.240.60: c 9522392www.di
2、n.deXDIN EN 12795Stra enverkehrstelematik Nahbereichskommunikation FahrzeugBake (DSRC) DSRC Datenverbindungsschicht: Zugriffsmedium und Verbindungssteuerung;Englische Fassung EN 12795:2003Road transport and traffic telematics Dedicated Short Range Communication (DSRC) DSRC data link layer: medium ac
3、cess andlogical link control;English version EN 12795:2003Tlmatique de la circulation et du transport routier Communication courte porte Couche liaison de contr le d accs au mdia et de contr le logique de liaison;Version anglaise 12795:2003Alleinverkauf der Normen durch Beuth Verlag GmbH, 10772 Berl
4、inwww.beuth.deGesamtumfang 49 SeitenDIN EN 12795:2005-10 2 Nationales Vorwort Die Europische Norm EN 12795 wurde vom Technischen Komitee CEN/TC278 Straenverkehrstele-matik“ unter deutscher Mitarbeit ausgearbeitet. Fr die deutsche Mitarbeit ist das Gemeinschaftskomitee GK 717 Straenverkehrstelematik“
5、 im Normenausschuss Kraftfahrzeuge (FAKRA) zustndig. Das Prsidium des DIN hat mit Prsidialbeschluss 13/1983 festgelegt, dass Deutsche Normen, deren Inhalt sich auf internationale Arbeitsergebnisse der Informationsverarbeitung grndet, in Ausnahmefllen und unter bestimmten Bedingungen allein in englis
6、cher Sprache verffentlicht werden drfen. Diese Bedingungen sind fr diese Norm erfllt. EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 12795March 2003ICS 35.100.20; 35.240.60 Supersedes ENV 12795:1997English versionRoad transport and traffic telematics - Dedicated Short RangeCommunication (DSRC) -
7、DSRC data link layer: medium accessand logical link controlTlmatique de la circulation et du Transport routier -Communication courte porte - Couche de liaison decontrle daccs au mdia et de contrle logique de liaisonThis European Standard was approved by CEN on 4 December 2002.CEN members are bound t
8、o comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Managem
9、ent Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the offic
10、ialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR S
11、TANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2003 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12795:2003 ETlmatique de la circulation et du trans
12、port routier - Communication courte porte - Couche liaison de contrle daccs au mdia et de contrle logique de liaisonEN 12795:2003 (E)2ContentspageForeword31 Scope 52 Normative references73 Terms and definitions .74 Abbreviations and variables.85 Frame format106 Address establishment .137 Medium Acce
13、ss Control (MAC) sublayer 158 Logical Link Control sublayer26Annex A (normative) Data link layer parameters .38Annex B (informative) Data link layer overhead.39Annex C (informative) Evolution of the MAC sequence bit.40Annex D (informative) Address establishment.42Annex E (informative) A-deviations.4
14、7EN 12795:2003 (E)3ForewordThis document (EN 12795:2003) has been prepared by Technical Committee CEN TC 278 “Road Transport andTraffic Telematics”, the secretariat of which is held by NEN.This European Standard shall be given the status of a national standard, either by publication of an identical
15、text orby endorsement, at the latest by September 2003, and conflicting national standards shall be withdrawn at thelatest by September 2003.This document supersedes ENV 12795:1997.The development of this standard was carried out under European Commission Mandate M/018.This European Standard forms p
16、art of a series of European Standards defining the framework of a Dedicated ShortRange Communication (DSRC) link in the Road Transport and Traffic Telematics (RTTT) environment.The communication requirements of many RTTT applications can be fulfilled by DSRC. The DSRC standardsenable compliant commu
17、nication systems to serve multiple RTTT applications in parallel.The small service areas and severe real-time constraints require a specific protocol architecture leading to thereduced protocol stack shown in Figure A, consisting of the Application Layer, the Data Link Layer, and thePhysical Layer.
18、Such architecture is very common for real-time environments.This European Standard gives the architecture and services offered by the DSRC Data Link Layer.Figure A DSRC protocol stackThe following set of European Standards for the DSRC link is issued by CEN: EN 12253 “DSRC Physical Layer using Micro
19、wave at 5.8 GHz”; EN 12795 “DSRC Data Link Layer: MAC and LLC” (this European Standard); EN 12834 “DSRC Application Layer“ ; EN 13372 “DSRC Profiles for RTTT Applications“.Annex A is normative. Annexes B, C, D and E are informative.EN 12795:2003 (E)4According to the CEN/CENELEC Internal Regulations,
20、 the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,Slovakia, Spain, Sweden, Switz
21、erland and the United Kingdom.EN 12795:2003 (E)51 ScopeThis European Standard: defines the Data Link Layer of DSRC; is positioned with respect to other related standards by the layers defined in OSI Basic Reference ModelEN ISO/IEC 7498-1 as adopted for DSRC; supports broadcast and half-duplex transm
22、ission modes; supports a variety of fixed equipment configurations. It supports configurations where one fixed equipmentcommunicates with one mobile equipment unit, as well as configurations where one fixed equipment cancommunicate with several mobile equipment units; takes into account that the mob
23、ile equipment communicates with the fixed equipment while passing through alimited communication zone; defines neither any specific configuration nor the layout of the communication zone; does not define to what extent different instances of fixed equipment, operating in the vicinity of each other,n
24、eed to be synchronised with each other; defines parameters to be used in negotiation procedures taking place between fixed equipment and mobileequipment.By defining two distinct sublayers, namely the medium access control sublayer and the logical link control sublayer,this standard defines:a) medium
25、 access control procedures for the shared physical medium;b) addressing rules and conventions;c) data flow control procedures;d) acknowledgement procedures;e) error control procedures;f) services provided to application layer.The MAC sublayer is specific to the DSRC. The LLC services offered are una
26、cknowledged and acknowledgedconnectionless services based on ISO/IEC 8802-2.EN 12795:2003 (E)6Figure 1 Architecture and data flow of the DSRC stackFigure 1 illustrates the global data flow between the elements of the DSRC stack, (Physical, Data Link andApplication Layers) and the application.NOTE Fo
27、r definitions of the terms used in Figure 1 see EN ISO/IEC 7498-1.EN 12795:2003 (E)72 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publicat
28、ions are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendmen
29、ts).EN ISO/IEC 7498-1:1995, Information technology Open Systems Interconnection Basic ReferenceModel: The Basic Model (ISO/IEC 7498-1:1994).ISO/IEC 8802-2, Information technology Telecommunications and information exchange between systems Local and metropolitan area networks Specific requirements Pa
30、rt 2: Logical link control.ISO/IEC 3309, Information technology Telecommunications and information exchange between systems High-level data link control (HDLC) procedures Frame structure.3 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply.3.1b
31、eacon service tabledata structure transmitted by the fixed equipment indicating available services3.2downlinkcommunication channel on which the fixed equipment transmits its information3.3fixed equipmentfixed communication facility with one or more downlink channels and, optionally, one or more upli
32、nk channelsNOTE Normally the fixed equipment is installed at a fixed location, but it may be installed on a mobile platform.3.4link identifierunique address used for addressing the mobile equipment3.5mobile equipmentmobile communication facility capable of receiving information from the fixed equipm
33、ent on the downlink and,optionally, also capable of transmitting information to the fixed equipment on the uplinkNOTE The mobile equipment normally corresponds to the vehicles communication unit.3.6profileunique set of parameter values controlling the behaviour of the DSRCEN 12795:2003 (E)83.7servic
34、e access pointinterface point between data link layer and application layer, that has a unique Link Identifier and that allows layersto communicateEN ISO/IEC 7498-1:19953.8uplinkcommunication channel on which mobile equipment transmits its information3.9windowperiod of time during which the physical
35、 medium is allocated either to the fixed equipment or to the mobileequipment4 Abbreviations and variablesFor the purposes of this European Standard, the following abbreviations and variables apply.4.1 Abbreviations4.1.1ACKACKnowledge4.1.2CanACKnowledged command / response4.1.3BSTBeacon Service Table
36、4.1.4C/RCommand/Response4.1.5FFinal4.1.6FCSFrame Check Sequence4.1.7FEFixed Equipment4.1.8HDLCHigh-level Data Link Control4.1.9LIDLink IdentifierEN 12795:2003 (E)94.1.10LPDULink layer Protocol Data Unit4.1.11LLCLogic Link Control4.1.12LSBLeast Significant Bit4.1.13LSDULink layer Service Data Unit4.1
37、.14L1Layer 1 of DSRC (Physical Layer)4.1.15L2Layer 2 of DSRC (Data Link Layer)4.1.16L7Application Layer Core of DSRC4.1.17MModifier function bit4.1.18MACMedium Access Control4.1.19MEMobile Equipment4.1.20MSBMost Significant Bit4.1.21OBUOn-Board Unit, an alternative descriptor to Mobile Equipment4.1.
38、22OSIOpen Systems Interconnection4.1.23PPoll4.1.24PDUProtocol Data UnitEN 12795:2003 (E)104.1.25P/FPoll/Final4.1.26RResponse4.1.27RRResponse Request4.1.28RSURoad Side Unit, an alternative descriptor to Fixed Equipment4.1.29SAPService Access Point4.1.30UIUnnumbered Information4.2 Variables4.2.1V(RI)r
39、eceive state variable (LLC)4.2.2V(SI)transmit state variable (LLC)5 Frame formatAll DSRC transmissions are in frames, and each frame conforms to the structure shown in Figure 2.Flag Link AddressFieldMAC ControlFieldLPDU Frame CheckSequenceFlagFigure 2 Frame structureFrames containing no LPDU form a
40、special case, see Figure 3.Flag Link AddressFieldMAC ControlFieldFrame CheckSequenceFlagFigure 3 Frame structure, no LPDUEN 12795:2003 (E)11NOTE The physical bit stream can also comprise a preamble and / or a trailing bits, see Figure 4.Preamble Layer 2 frame (including flags and zero bit insertion
41、between flags) Optional trailingbitsFigure 4 Physical layer bit stream5.1 FlagsAll frames shall start and end with a flag. A flag is a zero bit followed by six one bits followed by a zero bit (01111110). When in receiving state, all stations shall continuously check on a bit-by-bit basis for this se
42、quence. Atransmitter shall send only complete eight bit flags.The flag which ends a frame shall not be used as the start flag for the next frame.In order to achieve transparency the flag is prevented from accidentally occurring in the link address field, MACcontrol field, LPDU and frame check sequen
43、ce via a zero bit insertion procedure described in 5.7.5.2 Link address fieldThe link address field carries the Link Identifier (LID). The link address field shall contain either a private LID(contained in 4 octets), a multicast LID (contained in one octet) or a broadcast LID (contained in one octet
44、). TheLSB of each octet in the link address field is an extension bit.5.2.1 Private LIDThe private LID is a number in the range of 0 to 268435455. Thus the private LID consists of 28 bits. The privateLID is encoded into the link address field as shown in Figure 5.XXXXXXX0XXXXXXX0XXXXXXX0XXXXXXX17654
45、3210MSB LSBFigure 5 Private link address field formatThe LSB of the first three octets are set to 0 indicating that a further octet of the link address field follows. The LSBof the fourth octet is set to 1 indicating that this is the last octet of the link address field.5.2.2 Broadcast LIDThe broadc
46、ast LID equals 127. Thus the broadcast LID consists of 7 bits. The broadcast LID is encoded into thelink address field as in Figure 6.EN 12795:2003 (E)121111111176543210MSB LSBFigure 6 Broadcast link address field formatThe LSB of the link address field in Figure 6 is set to 1 indicating that it con
47、sists of one octet only.5.2.3 Multicast LIDThe multicast LID is a number in the range of 0 to 126. Thus the multicast LID consists of 7 bits. The multicast LID0 is reserved for test purposes and multicast LID in the range 120 to 126 are reserved for private use. The multicastLID is encoded into the
48、link address field as in Figure 7.XXXXXXX176543210MSB LSBX - other than all 1sFigure 7 Multicast link address field formatThe LSB of the link address field in Figure 7 is set to 1 indicating that it consists of one octet only.5.3 MAC Control control fieldThe MAC control field shall have the encoding
49、 as described in 7.3.2.5.4 LPDU formatThe LPDU shall have the encoding as described in 8.3.5.5 Frame Check SequenceAll frames shall include a 16-bit Frame Check Sequence (FCS) just prior to the end flag for error detectionpurposes. The contents of the link address field, MAC control field and LPDU shall be included in the calculation ofthe FCS.The FCS shall be compliant with 16-bit frame checking sequence as defined in ISO/IEC 3309 (3.6.2). Thegenerator polynomial shall be X16+ X12+
