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Joint Transportation Research Program JTRP FHWA/IN/JTRP-98/3 FinalReport BormanExpresswayPoint-to-PointWirelessModem JamesV.Krogmeier MichaelP.Fitz June2000 Indiana Department of Transportation Purdue University FinalReport FHWA/IN/JTRP-98/03 Borman Expressway Point-to-Point Modem Wireless By J. V. Krogmeier SchoolofElectricalandComputerEngineering PurdueUniversity JointTransportationResearchProgram ProjectNo.C-36-75H FileNo. 8-9-8 SPR-2036 InCooperationwiththe IndianaDepartmentofTransportation andthe U.S. DepartmentofTransportation FederalHighwayAdministration The contents ofthis reportreflectthe views ofthe authors who are responsible forthe facts and the accuracy ofthe data represented herein. The contents do not necessarily reflect the official views or policies of the Federal Highway Administration and the Indiana Department of Transportation.Thereportdoesnotconstituteastandard,specificationorregulation. PurdueUniversity WestLafayette,Indiana47907 June2000 Digitized by the Internet Archive in 2011 with funding from LYRASIS members and Sloan Foundation; Indiana Department of Transportation http://www.archive.org/details/bormanexpressway9803krog TECHNICALREPORTSTANDARDTITLEPAGE 1. ReportNo. 2.GovernmentAccessionNo. 3.Recipient'sCatalogNo. FHWAyLN/JTRP-98/13 4.TitleandSubtitle 5. ReportDate June2000 BormanExpresswayPoint-to-PointWirelessModem 6. PerformingOrganizationCode 7.Authors) 8. PerformingOrganization ReportNo. JamesV.KrogmeierandMichaelP.Fitz FHWA/IN/JTRP-98/3 9.PerformingOrganizationNameandAddress 10.WorkUnitNo. JointTransportationResearchProgram 1284CivilEngineeringBuilding PurdueUniversity WestLafavette.Indiana 47907-1284 11. ContractorGrantNo. SPR-2036 12.SponsoringAgencyNameandAddress 13.TypeofReportandPeriodCovered IndianaDepartmentofTransportation StateOfficeBuilding FinalReport 100NorthSenateAvenue Indianapolis,IN46204 14.SponsoringAgencyCode 15.SupplementaryNotes PreparedincooperationwiththeIndianaDepartmentofTransportationandFederalHighwayAdministration. 16.Abstract TheFederalHighwayAdministrationhasanationwideallocationoffivefrequencypairsinthe220-222MHzNarrowbandRadioServices bandwhichareintendedforapplicationinIntelligentTransportationSystems.ThesefrequenciesareavailableforusebystateDOTs (subjecttoFHWAapproval)andprovideanattractivesolutionforcertainlowtomediumbitratedatacommunicationsapplications. However,giventhelimitedbandwidthavailableinthesechannels,veryefficientmodemswillberequiredtomakemaximumbeneficial useofthisresource. Thegoalofthisprojectwastodesign,fieldtest,anddeployadigitalradiowhichusesthe220-222MHzspectralallocationandissuitable forstationarypoint-to-pointdatacommunicationsapplications.Thetargetapplicationforthisprojectwasthecontrol(pan,tilt,andzoom) ofavideocameralocatedattheinterchangeof1-65andtheBormanExpressway.Thewirelesslinkextendsfromthecameralocationto thetrafficoperationscenter(approximately 1.5miles).Therewerethreemaintasksneededtoproduceadeployablemodem: 1)interface circuitrywasrequiredbetweenthe220MHzmodemandthecameracontrolkeypadandthecamerapan/tilt/zoomreceiver,2)the fabricationofacompactandruggedtransmitterwasrequired,and3)thefabricationofacompactandruggedreceiverwasrequired.The receiversizeconstraintsweremoreexactingthanthoseofthetransmitterasthereceiverisdeployedinaroadsidecabinet,whilethe transmitterisdeployedinthetrafficmanagementcenter.Theworkplanwasdividedintoasetoftwelvetasks. The220MHzmodemcanserveINDOTasageneralpurposelinkforlowtomediumratedatacommunicationsinawidevarietyof applications.Themostsignificantissueoutstandingwithregardtowidespreadimplementationofthetechnologyisthemassproduction costandtheavailabilityofareliablesourceofproductionversionsofthedevice.EffortsarecontinuingatbothPurdueandOhioState towardfurthersimplificationsaimedatcomplexityreductioninthereceiver.Astopicsforfurtherstudy,thefollowingshouldbe considered: 1)adetailedcost/benefitanalysisshouldbemadecomparingthe220MHztechnologytootheralternativetechnologies,and 2)apreliminarydesignstudyofinteroperabilityissuesshouldbeperformedforthe220MHztechnologyintransportationapplications. 17.KeyWords 18.DistributionStatement wciarmeelreasscocnotmrmoul,nitcealteimoentrsy,dJaTtSa2tr2a0nsMmHiszsiaolnl.ocation,surveillance NNaotiroensatrlicTteicohnsn.icTahliIsndfoorcmuamteinotniSseravviaciel,ablSeprtiongtfhieelpdu,blVicAt2hr2o1u6g1hthe 19.SecurityClassif.(ofthisreport) 20.SecurityClassif.(ofthispage) 21.No.ofPages 22.Price Unclassified Unclassified 22 FormDOTF1700.7(8-69) 1 Table ofContents Abstract 5 1 Introduction 6 2 ProblemStatement 6 3 ObjectivesorPurpose 7 4 WorkPlan 7 5 AnalysisofData 9 5.1 DesignoftheInterfaceCircuitry 9 5.2 DesignofthePoint-to-PointModem 9 53 FieldTestingofthePoint-to-PointModem 1 5.4 IntegratedCircuitDevelopment 12 5.5 DeploymentandTestoftheBormanPoint-to-PointModem 13 6 Conclusions 75 7 Recommendations 16 8 ImplementationSuggestions 16 9 References 17 10 Appendices 19 AppendixA: TheDesignofthePoint-to-PointModem 19 A.l TrellisCodedModulation 19 A.1.1 Encoding 19 A.1.2 Decoding 21 A.1.3 ClosingtheTrellis 22 A.2 CarrierRecovery 22 A.2.1 TheDPLLoftheModem 23 A.2.2 TheLoopFilter 25 AppendixB: RealTimeImplementationofaSymbolTimingRecovery 27 B.l Introduction 27 B.2 TheSymbolTimingArchitecture 28 B.2.1 ThePrefilter 29 B.2.2 TheNonlinearity 29 B.2.3 ThePostfilter 29 B.2.4 TheSampler 30 B.3 ComplexityConsiderationsinDSPImplementation 30 B.3.1 HardwareDesign 30 B.3.2 ComplexityEstimation 31 B.3.3 ComplexityReduction 32 B.4 IllustrationofComplexity/PerformanceTradeoffs 33 AppendixC: Borman WirelessMODEMOperator'sManual 34 C.l Introduction 34 C.2 OverviewoftheModemSystem 35 C.2.1 InterfaceandProtocol 35 C.2.2 TransmitterUnit 35 C.2.3 ReceiverUnit 36 C.2.4 Accessories 36 C.3 EquipmentSetup 37 C.3.1 RadioTransmitter 37 C.3.2 RadioReceiver 38 C.4 Troubleshooting 38 C.4.1 NormalModeofOperation 38 C.4.2 TroubleshootingTips 39 C.5 Addenda 40 C.5.1 WiredTestModefortheKeypadandCameraController 40 List ofFigures Figure1: Thevicinityof1-65andtheBormanExpresswayinterchange. Whitestarsindicatethelocationsofthe TMCandthecamera. Thepoint-to-pointlinkofthisprojectislineofsightbetweenthetwostars 7 Figure2: Illustrationofmodemandcameracontrolinterface 9 Figure3: 220MHzModemBlockDiagrams, (a)Transmitter, (b)Receiver 10 Figure4: Receivedsignalconstellationsfromfieldtesting,(a)Receiverlocatedapproximately1.75milesfrom transmitter,(b)Receiverlocatedapproximately2.5milesfromtransmitter 12 Figure5: AblockdiagramoftheITSmodemreceiverandtheproposedblockstobeincorporatedintheIC development 12 Figure6: Basicfiniteimpulseresponsefilterarchitectureusedinsymboltimingrecoveryintegratedcircuit design. Theinputsamplerateis15kHzandthefilteroperatesona645kHzclocktocomputeone outputin43cycles, (a)Multiplyaccumulateblock, (b)Threestatefinitestatemachinecontroller 13 Figure7: LaboratoryviewoftheBormanPoint-to-PointModemHardware, (a)TransmitterbuiltbytheElectro- SciencesLaboratoryoftheOhioStateUniversity. Shownontopofthetransmitterboxisthecamera controloperator'stouchpadandjoystick, (b)ReceiverbuiltbyWelkinSystems. Shownontopofthe receiverboxisthecameracontrolpan/tilt/zoomreceiver 14 Figure8: TheBormanPoint-to-PointModemhardwaredeployedattheMillerUnit, (a)Transmitterantenna,(b) 220MHztransmitter(atleft)andvideo(atright)fromthecontrolledcamera 15 Figure9: TheBormanPoint-to-PointModemhardwaredeployedattheintersectionof1-65andtheBorman Expressway(seeninthebackground) 15 Figure10: ThesensorconcentrationscenarioasmightbeimplementedinafutureClineAvenueontheBorman Expressway 17 Figure11: V.32ConvolutionEncoder 19 Figure12: TrellisDiagram. Thefourgroupsofthreebitsnexttoeachstateinthetrelliscorrespondtothefour branchesleavingthestate 20 Figure13: V.32ConstellationPointMapping 20 Figure14: UncodedandTrellis-CodedBERCurves 21 Figure15: TransmitterFramingScheme 22 Figure16: TheSecond-OrderDPLLUsedintheModem 23 Figure17: TheS-curveforthePhaseDetectorofFigure16withaV.3232-QAMConstellation 24 Figure18: TheS-curveforthePhaseDetectorofFigure16withaV.32 128-QAMConstellation 24 Figure19: AverageAcquisitionTimesoftheDPLL 26 Figure20: Steady-stateBERcurvesofthemodem 27 Figure21: Matchedfilterandrecoveryalgorithm 28