in‐vehicle networking: a survey and look forward

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Slides of a talk given at the Workshop on Specialized Networks held in Conjunction with ETFA 2009.The use of networks for communications between the Electronic Control Units (ECU) of a vehicle in production cars dates from the beginning of the 90s. The specific requirements of the different car domains have led to the development of a large number of automotive networks such as LIN, J1850, CAN, FlexRay, MOST, etc.. This talk first introduces the context of in-vehicle embedded systems and, in particular, the requirements imposed on the communication systems. Then, we highlight future trends in the development of automotive communication systems.


  • InVehicleNetworking:a SurveyandLookForward NicolasNavet Workshop on Specialized Networks, ETFA09, Palma, Spain - 25/09/2009 ComplexityMastered
  • Outline 1. ArchitectureofAutomotiveEmbeddedSystems Whattheylooklike exampleofBMW Constraintsintheirdesign caseatVolvo Needforoptimizingresourceusage(ECU,networks) 2. TheAutosar CommunicationStack 3. AutomotiveNetworks TimeTriggeredversusEventTriggered ControllerAreaNetworkathighloads FlexRay conceptsandperformances 2009 INRIA / RealTime-at-Work - 2
  • ArchitectureofAutomotiveElectricaland Electronics(E/E)Systems 2009 INRIA / RealTime-at-Work - 3
  • Electronicsisthedriving forceofinnovation 90% of new functions use software Electronics: 40% of total costs Huge complexity: 70 ECUs, 2500 signals, 6 networks, multi-layered run-time environment (AUTOSAR), multi-source software, multi-core CPUs, etc Strongcosts,safety,reliability,timetomarket, reusability,legalconstraints! 2009 INRIA / RealTime-at-Work - 4
  • BMW7Series networking architecture[10] ZGW=central gateway 3CANbuses 1FlexRay Bus 1MOSTbus SeveralLINBuses (notshownhere) Ethernetisused foruploading code/parameters (EndofLine) Picture from [10] 2009 INRIA / RealTime-at-Work - 5
  • BMW7Series architecture wiring harness [10] 27Millions variants Each wiring harness is Body,audio, tailored to doors,battery, the wiringharnesses options Picture from [10] 2009 INRIA / RealTime-at-Work - 6
  • Therearemanynontechnicalissuesinthe designofE/Earchitecture The case at Volvo in [2] : Influence of E/E architecture wrt to business value? Architecturaldecisionsoften: lacks long term strategy lackwellacceptedprocess Lack of background in E/E at management level aremadeonexperience/ often mechanical background gutfeeling(poortool Lack of clear strategy between in-house and support) externalized developments Technical parameters are regarded as less important than cost for supplier / components selection Vehicle Family Management : How to share architecture and sub-systems between several brands/models with different constraints/objectives? Sub-optimal solutions for each component / function Legal / regulatory constraints 2009 INRIA / RealTime-at-Work - 7
  • ProliferationofECUs raisesproblems! 50 Number of ECUs (CAN/MOST/LIN) 45 40 35 30 25 20 15 Mercedes-Benz BMW 10 Audi 5 VW 0 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year Pictures from [3] LexusLS430hasmorethan100ECUs [wardsauto] 2009 INRIA / RealTime-at-Work - 8
  • Optimizingtheuseofnetworksisbecomingan industrialrequirementtoo Good reasons for optimizing : Complexity of the architectures (protocols, wiring, ECUs, gateways, etc ) Hardware cost, weight, room, fuel consumption, etc Need for incremental design Industrial risk and time to master new technologies (e.g. FlexRay) Performances (sometimes): a 60% loaded CAN network may be more efficient that two 30% networks interconnected by a gateway Some signals must be transmitted on several networks 2009 INRIA / RealTime-at-Work - 9 from [3]
  • Likelyupcomingarchitectures Fewer ECUs but more powerful Multi-core -controller Multi-source software Autosar OS strong protection mechanisms Virtualization ? ISO2626-2 dependability standard Backbone: FlexRay HighspeedCAN:500Kbit/s asbackbone FlexRay :10Mbit/s atBWMina Ethernet? fewyears[8] Picture from [8] 2009 INRIA / RealTime-at-Work - 10
  • AUTOSARCommunicationStack 2009 INRIA / RealTime-at-Work - 11
  • AUTOSARataglance AutomotiveOpenSystem Architecture Picture from [5] Industryinitiativethatis becomingadefactostandard Standardize:architecture(basic softwaremodulesinc. communication),methodology andexchangeformat, applicationinterfaces Benefits cost savings for legacy features Cooperateonstandards, quality through reuse and market competition competeonimplementation focus on real innovation versus basic enablers ability to re-allocate a function helps to master complexity Caveat:greatcomplexityandstillevolvingspecifications 2009 INRIA / RealTime-at-Work - 12
  • AUTOSARlayeredarchitecture: theglobalpicture Picture from [5] Supportednetworksare: CAN:ControllerArea Network LIN:LocalInterconnect Network MOST:MediaOriented SystemsTransport Ethernetintheupcoming releasefordiag./upload Vehicle Flashing Times [8]: 4th-generation BMW 7 series via CAN:


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