Vehicle Networks
Broadcast Systems
Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Outline Transport Protocol ExpertsGroup(TPEG) (RDS) Radio DataSystem interconnections Introduction: Wireless DGPS viaRDS RDS-TMC Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Networking types Wireless Interconnections Individuality – Delay – + Range + Scalability Broadcast Relevance o Individuality o Delay o Range o Scalability Cellular + Individuality + Delay Range – Scalability – Ad-hoc Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Broadcast Wireless Interconnections Disadvantages of broadcast: Disadvantages of Broadcast is superiortoothertechnologies to distributeinformationthat Why broadcast? Less appropriate todistribute individualized information Long delays Unidirectional (can becomplemented by cellular communication) data comprises large amountof is invariantfor a longertimeperiod, users, is relevantfora largenumberof Good scalability:usablewithmillions ofreceivers Long range:severalhundreds ofkilometerspossible Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Radio Data System (RDS) Radio Data Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Introduction toRDS per second added to an FM transmitted radiosignal an FM (87.5 MHz–108MHz) per secondadded to Structured datastream of673payload bit/s divided in11.4datagroups German “AutofahrerRundfunk Information(ARI)”system Hierarchical radio: low-bitrate digitaldataserviceforFM Standardized as CENELEC EN50067andIEC62106 First RDSreceiverspresented atIFA’87inBerlin RDS hasbeendeveloped inthe80’s asEuropean successor ofthe air introduced by Bosch/Blaupunkt in 1974 Bosch/Blaupunkt in air introducedby Requirements for RDSincluded backward-compatibility to ARI ARI: AM-signal at 57kHzsubcarrier toindicateannouncement on Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 RDS Applications Five mostimportantapplications („basic RDSfeatures“): mobile reception mode with car r with car mobile reception mode volume adjustments etc. announcements from time to frequencies (as channel numbers)oftransmitters thesameprogr particular programme regional code, andnumberpermittingidentificationofbroadcaster and All 5are implementedeverywhere and intendedprimarily tobeused in Traffic Announcement (TA) flag Traffic Programme (TP)flag lists: Oneormorelists,eachofup to25 Alternative Frequency(AF) name Programme Service(PS) Programme Identification(PI) : Setifprogramme provides traffic : 16-bit codecontainingcountrysymbol, :
: Set during announcement to enable during announcementto Set : : 8 alphanumeric case-sensitivechars : 8
adios with automatedtuning functions features serving as „tuning aids“ „tuning as serving features Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 RDS Applications(Cont‘d) disasters and hazardous chemical spills. disasters and emergency warningservices suchas national data for amount of by starttimeand datetoenable automatic on/off switchingofreceivers pop musicetc.) news, sport, current programmetype(e.g. mono, stereo) for thereceiver(e.g. Emergency Warning System (EWS) Emergency Warning System Radio Paging(RP) (RT) Radio Text Number (PIN) Programme Item (PTY) Programme Type Music Speech(MS)flag:Indicationwhethermusicor speech issent Decoder Information(DI) : 32or64characters oftextfordisplaybyreceivers : Paging function knownfrombeepersvia RDS : : Oneof31differentidentifiers to specifythe : Indicates one of a number ofoperatingmodes Indicates oneof : : Codeidentifying aparticularprogramme : Afeature using a very small Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 PLANAT, Bundesamt für Umwelt, Schweiz Image: Excurse: DisasterManagement Cycle Disaster Pre- RDS-EWS Disaster Post- Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 RDS Applications(Cont‘d) TA, PTYandPINoftheseservices for quickretuning,aswellTP, and AF broadcast servicesincludingPI transmit Traffic and Travel Information (TTI) messages and TravelInformation (TTI) transmit Traffic variable messagesigns DGPS messagesorcontrol of groups, e.g. available data still designed and implementedin be new applications to to receiversand associatedperipherals(e.g. printer) Traffic Message Channel (TMC): Popular adoption of theODA to Open DataApplication (ODA) Channel (TDC) Transparent Data Data channelforuseonlybybroadcaster In-House (IH): information (EON) Networks Enhanced Other Clock Time anddate(CT) : Reference time : Universal genericservicewhichpermits : : Providesfora continuousdatastream : cross-referencetoother Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 0.03 Multiplex-Spectrum of BasebandSignal 7kz±2.5kHz ± 57 kHz RDS sub-carrier D. Kopitz and B. Marks. D. Kopitz andB. Source: RDS: The RadioData System RDS: , Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Baseband Coding Structure Artech House, ISBN 0-89006-744-9, 1999. Artech House, ISBN Source: RDS: The RadioData System RDS: , D. Kopitz and B. Marks. Kopitz andB. , D. Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Error Protectionand Correction generator polynomial The codeisable tocorrectanysingleburstof aspanof5orlessbits The resultingcodehasthefollowing error-checkingcapabilities: Each transmitted26-bitblock does containa10bitCRCderivedwiththe spanning 11 bits,and about99,9%ofanylongerbursts Detects 100% error burstsspanning Detects allsingle anddoublebiterrorsinblock G(x) =x 10 + x 8 + x 7 + x 5 + x 4 ≤ + x 10 bits,99,8% of bursts 3 + 1 Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Flywheel Synchronization Mechanism synchronisation system inthe receiver/decoder („flywheel sync“) according to: an error-protectingcharacteristic preserving,blockspecificoffset the groupsorblocks. The purposeof adding the offsetwordistoprovide a groupandblock Before transmission,theCRC checksumissubjecttoaddition (mod 2)of Data transmissionisfullysynchronous, andtherearenogapsbetween D groups B for type C, for type C, Agroups B A Block 1101 010000 0110 1101 00 0110 0110 00 00 1111 0011 10-bit Offset Words added to CRC to 10-bit OffsetWordsadded 0101 1010 00 Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Artech House, ISBN 0-89006-744-9, 1999. Artech House, ISBN Source: Message Format PI code RDS: The RadioData System RDS: , D. Kopitz and B. Marks. Kopitz andB. , D. 0 i group 104 bit 87.6 ms ≈ 87.6 contains PI code contains PI group positions within a fixed occupy same always in group 2 always in First blockalways Messages normally PTY and TPflags Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 0A -group Example: Programme Service(PS)Name transmission channel overcome thechallenging this isamajor designcriteria to receiver – Obviously, data isbroadcasted in „chunks“and mustbeaccumulated at A totaloffourtype 0Agroupsarerequiredto transmitentirePSname Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Alternative Frequency (AF)Encoding 205 204 .. 2 1 206..255 0 Number Two listencodingmethods: Purpose: Facilitate theautomatic tuning. Method-B (> 25 alternatives): pairs of main transmitter + alternative 25 alternatives): pairsofmaintransmitter+ Method-B (> Method-A ( 1100 1101 1100 1100 0000 0010 0000 0001 .. 0000 0000 Binary Code ≤ 25alternatives):maintransmitter +alternatives list Not tobeused 107.9 MHz Carrier Frequency Filler Code for uneven # Filler Code for 87.7 MHz 87.6 MHz .. Special MeaningCodes Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Required DataRepetition Rates Any other 14A or14B 2A or2B 1A or1B 0A or0B Group types s hr sapefeiiiyt nelaetevrosknso messages of kinds needs various the the suit interleave to to flexibility ample is is, there xml uti:OFbodat D-M ihu o3groups/s to up RDS-TMC with Austria:ORFbroadcasts Example group;that of types various the of repetition of rhythm fixed no is There PI, PTY, TP, EON Features PI, PTY, TP, RT PI, PTY, TP, PIN Other applications PI, PS,PTY, TP, AF, TA, DI,MS Typicalof proportion 25% 10% 15% 10% transmitted groups ofthistype 40% (i.e. 4x0A/s) [Source: ResearchAndMarkets ] Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Traffic Message Channel (TMC) Traffic Message Coding at broadcaster-side needed Coding at Describing a trafficinformation event by: assist indynamic routeplanning Used to Given thecapacityofRDS,a maximum ofabout300TMCmessages/h! Receivers must beenabled to filteronly relevantmessages Language independentdigitally coded messages Objective: broadcastTrafficand TravelInformation(TTI) Universal event codes(upto 2048,currently ~1400) 16 bit) Local location codes(up toonly65.536 only– diversion Duration & Event (+parameters) parameters) Location (+ Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 TMC /ALERT-Cmessages No arbitrary locations; instead,lookup infixedtable oflocations 8A -group Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Example Message would beencoded usingthefollowingelements: The message Pfaffenhofen exit U31 from the Holledau. Deviationrecommended via traffic between exit Pfaffenhofenandmotorwayinterchange Location Code Event Extend: 2fortwolocations backwardintheloctable Direction of event(+/-) Diversion (D) Duration (DP) Munich-Nuremberg, directionNuremberg,stationary Motorway A9 : 101for stationarytraffic : 1fordeviation being recommended : 0fornospecific duration : 12735 formotorwayinterchange Holledau : 1fornegative Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 tables only? location lookup What doesitalsomean tohave xxxxxxxxx MFG Selbstverständlich stehe ich Ihnen Bitte setzenSiesichmit Ihrem dargestellt werden. nichterfasstenStra Locationkatalog und über werden digitalkodiert TMC vorliegen, wichtigsten TeilStraßennetzes. österreichischen Alle des Autobahnen, alle Schnellstraßen, alleBundesstraßen vorgegeben. ORF dem verkehrsrelevanten Ereignisse ist undEvent Location- einem fixen RDS-TMC basiertauf diese schon? Haben Sie Österreich). (Version 1.0- können, empfangen zu Österreich in Um TMC Ö3 strahltseit16.Oktober Lieber Ö3-Hörer! Answer of Ö3toaquestionfromtheaudience: 2002 TMC über die Ö3-Frequenz ab. Ö3-Frequenz die über 2002 TMC äde nVridn derkannI Händler in Verbindung - für weitere Rückfragen zur Verfügung. e Lne- eik-und Gemeindes ßen (Landes-, Bezirks- brauchen Sie die aktuelle Location Code CD Code aktuelle Location die brauchen Sie versendet. NurVerkehrsbehinderungen auf denvom und eine Auswahl wichtiger Landesstraßen - somit den somit und eine wichtiger Landesstraßen- Auswahl geographischen Punkte und katalog. DieSummeder geographischenPunkte Der österreichische Locationkatalog umfasst alle umfasst österreichische Locationkatalog Der Verkehrsbehinderungen, die hnen dieaktuellsteL-CD besorgen. traßen) können über TMC nicht traßen) könnenüberTMC der ORF-Verkehrsredaktion Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Security in TMC described at using an encryptedversionofthelocationtable quality TMC services(stillintheboundaries of thetechnicalcapabilities) Lack ofsecurity mechanism allows crazythings such astheones Some serviceproviders(e.g. private radiocompanies)sell„better“ TMC services isprovidedfree-of-charge The majorityof http://dev.inversepath.com/rds/cansecwest_2007.pdf Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 There are several satellite navigation systems with global coverage: There areseveralsatellitenavigation systems Excurse: Global Navigation SatelliteSystems(GNSS) COMPASS (intheFuture) GALILEO (inthe future) GLONASS GPS civilian & public regulated civilian & China 5 basicservices: Europe; Russia; military 2 basicservices USA; military 4 nav+1SAR-com Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 The of the3unknowns determination requires thereceptionof thesignals Principle ofGNSS:Ranging of 3navigation satellites navigation signals fromthesatellitetoreceiver SatNav isbasedonthemeasurement ofthepropagationdelay ranges“ betweensatelliteand receiveraredetermined Ranging X R , Y R , Z R based onthemeasured ρ 1 time ρ 2 delays, so-called„pseudo X R , Y Æ R δ , Z t ρ 1 3 , δ R t Æ ρ 2 , i δ ρ = cδ t 1 3 , ρ 2 , t ρ i 3 Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Principle ofGNSS:Ranging Solution Problem: distance (in 1 distance (in to theclocksofsatellites ispracticallyimpossible which satellite’s clocks- Use signals of 4 different satellites to determine 3Dposition 4 differentsatellitesto Use signalsof A timeuncertaintyof1nsmeans 30cmin Hence, the receiver‘sclockisoffset withrespect the be synchronised to Receiver hasto μ s thesignaltravels300m)! ρ 1 ρ 2 ρ 3 ρ 4 Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Sources ofGNSSerrors Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Error MitigationbyAugmentation Wide Area Augmentation System Wide AreaAugmentation Monitoring Network correction Ground based data correction data Local Augmentation System Local Augmentation Monitor Station correction local data regional station DGPS … Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 DGPS as RDS-ODApayload plctosta r iie o±1..5maccuracy applications that arelimitedto± manufacturers and areusedasa guideline for DGPSviaRDS No standardized mapping, split/reconstruct/mapping is proprietary! No standardized mapping, split/reconstruct/mapping is Example: RTCM formatitselfisunsuitable for RDSduetoexcessivebandwidth The lowdataratesofferedby RDSaresuitableonlyforDGPS RTCM SC-104DGPSprotocol formatiswidely used byGPS 333 bits asODA payload, split and independent of other sats. be possible Such message for9satellites (680bits) iscompressed to9x37= Type 1RTCM message (mostfrequentone) is500..700bitslong (recall: one ODAgroup typeA(e.g.11A)cancarry 37payload bits) 5maccuracy, 20-50bpswithinRDS-ODA sufficient To achieve± Compression (and decompression atreceiver)required several centimeters would Confer, ate.g.2.400bpsanaccuracy of Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Literature http://www.amazon.de/Rds-Radio-System-Art ech-Telecommunicati ons/dp/0890067449 Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Group (TPEG) Transport Protocol Experts Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Overview TPEG and Travel Information (TTI) and TravelInformation Services Association (TISA) project led byBMW Supported by TPEG Groupand TMCForumhavemerged to Broadcast transmissionof Standardized by CENandISO Founded in1998by Transport ProtocolExpertsGroup (TPEG) mobile.info European BroadcastingUnion (EBU) language-independent multi-modal in 2008 No. of layer 7 1 2 3 4 5 6 ISO/OSI refmodel Presentation Application Data Link Transport Physical Network Session Traveller Information • • • • Encryption Multiplexing Information encoding Error detection/correction TPEG protocol specification Arbitrary bearer TPEG Traffic Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 TPEG mobile.info: TPEGAutomotive Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Drawbacks of RDS-TMC TPEG No extensibility No encryption, authentication) security mechanisms(e.g. message No pre-defined location table location referencingaccordingto Static time Max. 300messagesata 2 Pre-defined eventdescriptions(max. data rate(~100byte/s) Low single bearer (RDS) a Limited to Public Transport Information Application 11 11 Road Traffic Information Road Traffic Weather Information types of events) types of Bearer RDS-TMC TMC RDS GSM/UMTS Bearer independent Extensible (applicationplugins) Optional message encryption Dynamic locationreferencing Extensible eventtypes High data rates (depend on bearer) Variable number ofmessages DAB TPEG TPEG DMB Internet … Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Applications TPEG … (more will bedefined in thefuture) Parking Information PKI – Compact Event Traffic TEC – Public TransportInformation PTI – Messages Traffic Road RTM – Timetable changes for busses, trains, ferries, planes, etc. ferries, busses, trains, Timetable changes for Dynamic: Parking space availability Dynamic: Parking Static: Parking area information roadworks, accidents) tra road Event-driven messages for ffic information(e.g. congestion, Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Message Management Message format TPEG … Frame TPEG-Message Message Management Event Container (e.g. RTM) Frame TPEG-Message Multiplexed datastream Event Container (e.g. PKI) TPEG-Message Location Container TPEG-Message Location Container … Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 MID Message Management Container TPEG Equal format for all application types for Equal format (severity) parameters General specification of time(start&expiry times)andimportance MGT MET VER STA STO SEV UNV CRI Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Event Container TPEG congestion) container can bebasedondifferentkindsofapplication data: Extendable (additional applications can be defined) Extendable (additional applicationscanbe Events canbe linked withcause-effectrelation (accidentcauses Depending on thetypeofapplication (RTM, PKI, TEC,…)theevent T Road Traffic Messages RTM – lots) Points-of-Interest: e.g.parking (occupancy,numberoffreeparking Availability, delay Public transport: Individual transport: Accidents,congestion, road condition K Parking Information PKI – Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 TPEG Automotive Profile(TAP) TPEG Parking Info (PKI): Parking Info (SPI): Speed Info Traffic Flow and Prediction (TFP): Traffic Weather(WEA): Local Hazard Warning(LHW): Traffic EventCompact(TEC): Profiles definefixedmessagety road, obstacles, “ghost driver”) slippery (e.g. Dangerous situations TMC Similar to roadworks, accidents) traffic information(e.g.congestion, road Event-driven messagesfor Occupancy, number of free parking lots speed restrictions E.g. temporal states of theroadnetwork Current andupcoming traffic Information about weather conditions
pes for specific application fields (e.g. automotive) specific application fields(e.g. for pes
standardization Currently in Currently Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Location Referencing TPEG On-The-Fly Pre-coded by specificcodes Definition: Identification ofparts Æ on demand(On-The-Fly) encoded dynamically Locations are E.g. pre-defined locationtables encoded using Locations are ..ra eto intr {functi roadsectionsignature = e.g. and optional attributes + mandatory WGS-84) inter-linked coordinates(e.g. Locations are encodedby asetof Map actsadynamic locationtable and decoding of locations isdifferent decoding of and problem ifmapdata forencoding Loc333-ext2-3km (e.g. ALERT-C in TMC): (AGORA-C inTPEG): onal road class, form-of-way, road onal roadclass, the roadnetworkandot Schneebauer, Wa Map 1 rtenberg (2007): On-The-Fly Location Referencing her geographic objects descriptor, driving direction} Map 2 … Loc 334 Loc 333 Loc 332 Location Table Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 TMC/ALERT-C TPEG approaches, intersections, servicestations,bridges and tunnels Loc333, ext 2 Loc333, ext road network Æ Linear locations are encoded by their start location and direction (e.g. location and start their encoded by Linear locations are their predecessorandsuccessor onthe Location codesarelinkedto Distances between consecutive codes maybelargerthan10km 2 16 difficult tospecifyexactlocations pre-defined hierarchical-ordered location codes forhighway ) andtheextent oflocationstillthestoplocation (e.g. 3km) Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 AGORA-C TPEG available message or safetyalert the spatial information) ondemand(on-the-fly) for information Can beusedas extensiontoALERT-Cwhen locationcodeisnot 98% hit ratewith35 bytelocation codes isfeasible (“ Small size meta Standardized of referencepoints + location description(i.e.set Flexible, dynamic geo-referencing of trafficandsafety-related C” = compact) – less than60bytes less = compact)– footprint of atraffic Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Location Container TPEG Different types: Coordinates Korean-Node-Link: Korean locationreferencing VICS-Link: Japaneselocation referencing AGORA-C: Onlythickclients TPEG-Loc: Thin(w/omaps,only text)orthick(withmaps)clients ALERT-C: TMClocationreferencing WGS-84 Location Location Type Expansion Radius of Mode Type List Mode Type Height Coordinates Descriptor1 No. Default Language TPEG-Loc Code Management Message Frame Descriptor2 No. Coordinates Event Container TPEG-Loc Location (e.g. RTM) Descriptor3 No. TPEG-Message Add. Location Description TPEG-Loc Container Location Intersection Intersection Descriptor Name Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Encryption TPEG Symmetric encryption (=shared keys)withcascading key hierarchy for: prevent correlation attacks control word, Service data:en/decryption with mess Services: en-/decryption of data with ev included in Individual devices:devicekey service keys ages with temporary session keys ( ages with Unbehaun, Scholz Unbehaun, (2007): Key Design for Efficient ery device, en-/decryption of management ery device, en-/decryption of control word has to be changed frequently to control wordhas to Encoder control word ) Broadcasting of Traffic Broadcasting Services Information Decoder Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 Formats TPEG tpegML TPEG Binary: Multimedia Broadcast (DMB) Multimedia Broadcast For transmission over the Internet or XML encoding For transmissionover Binary encoding : Word Sync Sync Length Field Frame Type Header Header CRC Digital Audio Broadcast (DAB) Digital AudioBroadcast Component ID Component Service Service Service Service ID Encryption ID Length Field Service Component Message TPEG Digital Video Broadcast (DVB) Digital Video Broadcast Frame CRC Message Service Component TPEG Service 256 … Data 4x10 Service Component … or 9 Frame Digital Message TPEG Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 tpegML TPEG
Source: http://www.bbc.co.uk/travel Container
Management
Event Event news/tpeg/en/local/rtm/rtm_tpeg.xml Container Location
Container Message Road Traffic Message Traffic Road Lecture Vehicle Networks, Thomas Strang and Matthias Röckl, WS 2008/2009 XSL Transformation TPEG <…> XSL ….