SIST EN 301 391 V1.1.1:2003
(Main)ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM); Data communications using short range devices; Access protocol, occupation rules and corresponding technical characteristics for the transmission of data
General Information
- Abstract
This EN covers both the basic radio parameters and the protocols to be used with low power devices sending short packets of data, e.g. consumer electronic equipment.
- Status
- Published
- Publication Date
- 30-Nov-2003
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Dec-2003
- Due Date
- 01-Dec-2003
- Completion Date
- 01-Dec-2003
Overview
SIST EN 301 391 V1.1.1:2003 is a European standard developed by the Slovenski inštitut za standardizacijo (SIST) in alignment with ETSI requirements. This standard focuses on ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM), providing essential guidelines for data communications using short range devices (SRDs). The document details the access protocol, channel occupation rules, and the associated technical characteristics necessary for the reliable transmission of small data packets over radio frequencies.
This standard is specifically designed for low-power equipment, such as consumer electronics, that send short bursts of data. By establishing uniform protocols and measurement methods, it aims to ensure device interoperability, minimize interference, and optimize use of the radio spectrum.
Key Topics
- Electromagnetic Compatibility (EMC): Ensures that short range devices can operate without causing or suffering from unacceptable electromagnetic disturbance.
- Access Protocol: Defines how devices determine if a radio channel is available and the process to initiate data transmission safely and efficiently.
- Channel Occupation Rules: Limits the duration and frequency of channel use, preventing single devices from monopolizing the radio spectrum.
- Technical Characteristics: Covers vital device specifications, including duty cycle limitations, carrier sense thresholds, and methods to avoid data collision.
- Measurement Methods: Outlines procedures and parameters for testing device compliance, including channel access duration, carrier sense delay, and antiblocking measures.
- Conformity Requirements: Manufacturers must provide declarations and submit products for testing to accredited laboratories to ensure compliance.
Applications
The standard is highly relevant in a variety of practical scenarios, particularly where short range, low power, packet-based wireless communication is required:
- Consumer Electronics: Devices such as remote controls, smart home sensors, wireless key fobs, and gaming peripherals benefit from standardized access protocols for reliable performance.
- Industrial Automation: Wireless controllers and monitoring equipment in industrial environments use the specified protocols to prevent interference in crowded RF environments.
- Building Automation: Systems such as security sensors, lighting control, and HVAC management use short-range wireless data exchange.
- Health and Medical Devices: Wearable devices and patient monitoring sensors utilize the standard’s guidelines for safe and effective data transmission.
- General SRD Communication: Applies to all applications that require infrequent, small data packet transfers - emphasizing control and limited data transfer rather than continuous data streams.
Related Standards
SIST EN 301 391 V1.1.1:2003 references several other important standards and recommendations, which provide deeper guidelines for specific frequency bands, device types, and compliance methods:
- EN 300 220-1: Technical characteristics and test methods for radio equipment in the 25 MHz to 1000 MHz range.
- EN 300 330: Characteristics and test methods for SRDs operating from 9 kHz to 25 MHz.
- I-ETS 300 440: Technical characteristics for SRDs in the 1 GHz to 25 GHz range.
- CEPT/ERC Recommendation 70-03: General recommendations for the use of short range devices across Europe.
- ETR 273-series: Detailed measurement methods and evaluation of uncertainties for radiated tests, including various test site arrangements.
Practical Value
Adherence to SIST EN 301 391 V1.1.1:2003 enables manufacturers to:
- Meet regulatory and market requirements for electromagnetic compatibility.
- Facilitate coexistence of multiple wireless devices by reducing interference.
- Accelerate product certification and market entry by aligning with harmonized testing protocols.
- Enhance user experience through reliable, interference-free device operation.
- Ensure interoperability with other certified devices, supporting a more robust and scalable ecosystem for short range wireless communication.
This document is an essential reference for engineers, compliance managers, and manufacturers developing wireless solutions using short range communication in consumer and industrial domains.
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Frequently Asked Questions
SIST EN 301 391 V1.1.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM); Data communications using short range devices; Access protocol, occupation rules and corresponding technical characteristics for the transmission of data". This standard covers: This EN covers both the basic radio parameters and the protocols to be used with low power devices sending short packets of data, e.g. consumer electronic equipment.
This EN covers both the basic radio parameters and the protocols to be used with low power devices sending short packets of data, e.g. consumer electronic equipment.
SIST EN 301 391 V1.1.1:2003 is classified under the following ICS (International Classification for Standards) categories: 33.060.99 - Other equipment for radiocommunications; 33.100.01 - Electromagnetic compatibility in general. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 301 391 V1.1.1:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM); Data communications using short range devices; Access protocol, occupation rules and corresponding technical characteristics for the transmission of data33.100.01Elektromagnetna združljivost na splošnoElectromagnetic compatibility in general33.060.99Druga oprema za radijske komunikacijeOther equipment for radiocommunicationsICS:Ta slovenski standard je istoveten z:EN 301 391 Version 1.1.1SIST EN 301 391 V1.1.1:2003en01-december-2003SIST EN 301 391 V1.1.1:2003SLOVENSKI
STANDARD
ETSIEN301391V1.1.1(2000-01)EuropeanStandard(Telecommunicationsseries)ElectromagneticcompatibilityandRadiospectrumMatters(ERM);Datacommunicationsusingshortrangedevices;Accessprotocol,occupationrulesandcorrespondingtechnicalcharacteristicsforthetransmissionofdataSIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)2ReferenceDEN/ERM-RP02-034Keywordsaccess,data,mobile,protocol,radioETSIPostaladdressF-06921SophiaAntipolisCedex-FRANCEOfficeaddress650RoutedesLucioles-SophiaAntipolisValbonne-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88Internetsecretariat@etsi.frIndividualcopiesofthisETSIdeliverablecanbedownloadedfromhttp://www.etsi.orgIfyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frImportantnoticeThisETSIdeliverablemaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.CopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)3ContentsIntellectualPropertyRights.5Foreword.5Introduction.51Scope.62References.63Definitions,symbolsandabbreviations.73.1Definitions.73.2Symbols.73.3Abbreviations.84General.84.1Applicationsusingthisprotocol.84.2Conformitytothepresentdocument.84.2.1Declarationofconformity.84.2.2Measurementstobeperformed.94.2.3Interpretationofthemeasurementresults.95Technicalcharacteristicsoftheequipment.96Descriptionoftheaccessprotocol.96.1Channelaccessduration.96.2Principles.106.3Procedure.106.4Carriersensing.106.5Observationtime.116.6Messageprioritydelay.116.7DutyCycle.116.8Antiblocking.117Methodsofmeasurementandlimits.127.1Channelaccessduration.127.1.1Definition.127.1.2Methodofmeasurement.127.1.2.1Asingletransmitteraccessingthechannel.127.1.2.2Morethanonetransmitteraccessingthechannel.137.1.3Limit.137.2Replycarrierdelay.137.2.1Definition.137.2.2Methodofmeasurement.137.2.3Limit.137.3Antiblocking.137.3.1Definition.137.3.2Methodofmeasurement.147.3.3Limit.147.4Carriersensethreshold.147.4.1Definition.147.4.2Methodofmeasurement.147.4.3Limit.157.5Carriersensedelay.157.5.1Definition.157.5.2Methodofmeasurement.167.5.3Limit.167.6Observationtime.167.6.1Definition.16SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)47.6.2Methodofmeasurement.167.6.3Limit.177.7Channelaccessingcarrierattacktime.177.7.1Definition.177.7.2Methodofmeasurement.187.7.3Limit.188Examplesofchannelaccesstiming.199Measurementuncertainty.20AnnexA(normative):Radiatedmeasurement.21A.1Testsitesandgeneralarrangementsformeasurementsinvolvingtheuseofradiatedfields.21A.1.1Anechoicchamber.21A.1.2Anechoicchamberwithaconductivegroundplane.22A.1.3OATS.23A.1.4Testantenna.24A.1.5Substitutionantenna.25A.1.6Measuringantenna.25A.2Guidanceontheuseofradiationtestsites.25A.2.1Verificationofthetestsite.25A.2.2PreparationoftheEUT.25A.2.3PowersuppliestotheEUT.25A.2.4Volumecontrolsettingforanaloguespeechtests.26A.2.5Rangelength.26A.2.6Sitepreparation.26A.3Couplingofsignals.27A.3.1General.27A.3.2DataSignals.27A.3.3Speechandanaloguesignals.27A.3.3.1Acousticcouplerdescription.28A.3.3.2Calibration.28Bibliography.29History.30SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)5IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinSR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinSR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeElectromagneticcompatibilityandRadiospectrumMatters(ERM).AnnexAisnormativeandprovidesadditionalinformationconcerningmeasurements.NationaltranspositiondatesDateofadoptionofthisEN:31December1999DateoflatestannouncementofthisEN(doa):31March2000DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):30September2000DateofwithdrawalofanyconflictingNationalStandard(dow):30September2000IntroductionThepresentdocumentspecifiesanaccessprotocolintendedtobeusedinequipmentemployingshortrange(radio)devicesforthecordlesstransferofsmalldatapackets.Itisintendedthattheimplementationofthisprotocolissufficientlysimpletosuitthelowcostsnecessaryforsomeproducts.Thepresentdocumentreliesonallequipmentonasharedchannelusingthisprotocol.Theprotocolallowsefficientchannelsharinginhighdatatrafficsituations,andhasbeendevisedtoprovideanequitablesharebetweenallusersofthechannel.Thepresentdocumentonlyappliestoapplicationsthatrequireinfrequentburstsofsmalldatapacketsforthepurposeofcontrolandlimiteddatatransferi.e.notcontinuousunbrokendatatransmission.Thisprotocolreliesontherebeingalimitedradiatedpowerandthereforealimitedrange,thusrestrictingtheoverlapoflocalusers(cellsize)toalevelwheretheprotocolcancopebytimesharingbetweenthem.Datacollisionisminimizedinthisprotocolbyusingcarriersensemultipleaccess(CSMA)whichrequiresthattheradiochannelissilentbeforestartinganytransmission.Arbitrationbetweencompetingusersisachievedbyusingapseudorandomlengthdelayperiodbeforetransmitting.Amechanismforprioritizingmessages,basedonmessagelength,isalsoprovidedaspartofthearbitrationprocess.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)61ScopeThepresentdocumentcoversaradiochannelaccessprotocolandprovidesalltheparametersthatareessentialforitsuse.ThepresentdocumenthasbeendesignedtobeusedwithShortRangeDevicessharingacommon,singlefrequency,radiochannelandtransmittingsmall(shortduration)datapackets.StandardsEN300220-1[1],EN300330[2]andI-ETS300440[3]providetechnicalcharacteristicsforshortrangedeviceequipment.Theseproductswillbeco-existingonthesameradiospectrum.Thepresentdocumentspecifiestheaccessprotocolandtheoccupationrulesfordatacommunicationsonaradiochannelsharedbydifferentusers.Thepresentdocumentdoesnotspecifyorimposeanyrestrictiononthebitrate,dataformatormodulationscheme.Thisaccessprotocolisnotintendedforapplicationsrequiringcontinuous(unbroken)datatransmission.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.•Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.•Foraspecificreference,subsequentrevisionsdonotapply.•Foranon-specificreference,thelatestversionapplies.•Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.[1]EN300220-1(V1.2):"ElectromagneticcompatibilityandRadiospectrumMatters(ERM);Shortrangedevices;Technicalcharacteristicsandtestmethodsforradioequipmenttobeusedinthe25MHzto1000MHzfrequencyrangewithpowerlevelsrangingupto500mW;Part1:Parametersintendedforregulatorypurposes".[2]EN300330:"ElectromagneticcompatibilityandRadiospectrumMatters(ERM);ShortRangeDevices(SRD);Technicalcharacteristicsandtestmethodsforradioequipmentinthefrequencyrange9kHzto25MHzandinductiveloopsystemsinthefrequencyrange9kHzto30MHz".[3]I-ETS300440:"RadioEquipmentandSystems(RES);ShortRangeDevices(SRDs);Technicalcharacteristicsandtestmethodsforradioequipmenttobeusedinthe1GHzto25GHzfrequencyrange".[4]ETS300113:"RadioEquipmentandSystems(RES);Landmobileservice;Technicalcharacteristicsandtestconditionsforradioequipmentintendedforthetransmissionofdata(andspeech)andhavinganantennaconnector".[5]ETR273-2:"ElectromagneticcompatibilityandRadiospectrumMatters(ERM);Improvementofradiatedmethodsofmeasurement(usingtestsites)andevaluationofthecorrespondingmeasurementuncertainties;Part2:Anechoicchamber".[6]ETR273-3:"ElectromagneticcompatibilityandRadiospectrumMatters(ERM);Improvementofradiatedmethodsofmeasurement(usingtestsites)andevaluationofthecorrespondingmeasurementuncertainties;Part3:Anechoicchamberwithagroundplane".[7]ETR273-4:"ElectromagneticcompatibilityandRadiospectrumMatters(ERM);Improvementofradiatedmethodsofmeasurement(usingtestsites)andevaluationofthecorrespondingmeasurementuncertainties;Part4:Openareatestsite".SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)7[8]CEPT/ERCRecommendation70-03:"RelatingtotheuseofShortRangeDevices(SRD)".IncludingAppendicesandAnnexes.[9]IECPublication60489-3:"Methodsofmeasurementforradioequipmentusedinthemobileservices.Part3:ReceiversforA3EorF3Eemissions".3Definitions,symbolsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply:attacktime:timetakenbetweenestablishingthatthechannelcanbeaccessedtotheactualinstantofaccess.Thedetaileddefinitionisgiveninsubclause7.7observationtime:definitionisgiveninsubclause6.5bit:binarydigitdatapacket:smallestquantityofdatasentovertheradiochannelinoneaccessperiod.Anumberofusefulbitsarealwayssenttogetherwithcorrespondingredundancybitsinanygivenpacket.Anacknowledgereply,ifused,isalsoincludedinthepacketmessage:userdatatobetransferredinoneormorepacketsinasessionmessagelength:timetakentotransmitamessage;thesumofthecarrierontimeofallthedatapacketsusedandthecarrieroff(silence)timesofallthedatapacketsusedreply:transmissionbyadeviceinanswertothe"initiatingtransmitter".Thisreplycanbeanacknowledge("ACK")oranegativeacknowledge("NACK")and/oralongerpacketofuseful/requestedinformationreplycarrierdelay:timeperiodbetweenendofatransmissionandstartofanacknowledge/replysilence:conditionofnodetectedcarrierenergyintheradiochannelinquestiontransmission(physical):onepackettransmittedbetweencarrieronandfinalcarrieroffofaparticulartransmitter3.2SymbolsForthepurposesofthepresentdocument,thefollowingsymbolsapply:dBdecibeldBmdBrelativeto1mWdBµVdBrelativeto1µVTxtransmitter(radio)SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)83.3AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:ACKACKnowledgeASKAmplitudeShiftKeyingCSMACarrierSenseMultipleAccessEUTEquipmentUnderTestfccarrierfrequency(bandcentre)FSKFrequencyShiftKeyingNACKNegativeACKnowledgeOATSOpenAreaTestSitePcSteadystatetransmitpowerPmeanMeanleveloftransmitpowerPoffcarrieroffpowerlevelPraccminimumreceiversensitivityneededtocheckthatachannelisfreePrcheckreceivedcarrierpowerlevel,generatedbyacheckingtransmitterPSKPhaseShiftKeyingQAMQuadratureAmplitudeModulationRFRadioFrequencytcreplycarrierdelaytimetffixedpartofobservationtimetoobservationtimetpprioritypartofobservationtimetrpseudorandompartofobservationtime4General4.1ApplicationsusingthisprotocolThisaccessprotocolappliestoawidevarietyofapplicationsoperatingatvariousdataratesinbothdomesticandindustrialfields.Toaccommodatethissituation,fourprioritylevelsareincludedwhichcorrespondtodifferentdatapacketlengths.This,forexample,improvesthechanceofaccessforasimplecontrolfunction(requiringafastresponsetime)infavourofafunctiontransferringalargeamountofdata(lesscriticalofresponsetime).Theprotocolmaybeusedwiththefollowingtypesofcommunication:-point-to-point(sourcetodestination);-point-to-multi-point(sourcetogroup);-multi-point-to-point(polling).4.2ConformitytothepresentdocumentConformitytotherequirementsofthepresentdocumentisbaseduponbothdeclarationsandmeasurements.4.2.1DeclarationofconformityThoseparameterscoveredbymanufacturersdeclarationaregiveninclause6ofthepresentdocument.Asigneddeclarationshallbeprovidedasconfirmationthattheequipmentmeetstherequirementsofthisaccessprotocol.Thisdeclarationmaybesubmittedbythemanufacturer,orhisrepresentative,togetherwiththeapplicationformfortests.Inthecasewherethecontrollingsoftwarefortheequipment(ormodulesthereof)hasnotbeendesignedbythemanufactureroftheradioequipment,theresponsiblepartyforengineeringsuchsoftwareshallalsoprovideasigneddeclarationofconformity.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)94.2.2MeasurementstobeperformedThesemeasurementsshallbeperformedforallpartsoftheequipmentincludedinthesystem,designedtousethisprotocol.Clause7ofthepresentdocumentgivesthemethodsofmeasurementsandlimitsfortheseparameters.Themanufacturershallprovideanynecessarytestpointsand/ortestfixtures,dedicatedtestequipment(ifneeded)and/ortestmodesforthepurposeoftestingandmakingmeasurements.Thefollowingmeasurementsandtestsshallbeperformed,inanaccreditedtestlaboratory:-channelaccessduration;-replycarrierdelay;-antiblocking;-carriersensethreshold;-carriersensedelay;-observationtime;-channelaccessingcarrierattacktime.4.2.3InterpretationofthemeasurementresultsTheinterpretationofthemeasurementresultsrecordedinatestreportforthemeasurementsdescribedinthepresentdocumentshallbeasfollows:a)themeasuredvaluerelatedtothecorrespondinglimitshallbeusedtodecidewhethertheequipmentundertestmeetstherequirementsofthepresentdocumentornot;b)theactualmeasurementuncertaintyofthetestlaboratorycarryingoutthemeasurement,foreachparticularmeasurement,shallbeincludedinthetestreport;c)thevaluesoftheactualmeasurementuncertaintyshallbe,foreachmeasurement,equaltoorlowerthanthefiguresgiveninclause9,absolutemeasurementuncertainties.5TechnicalcharacteristicsoftheequipmentThisprotocolisintendedtobeusedbyshortrangedevicesfulfillingtherequirementsofEN300220-1[1],EN300330[2]andI-ETS300440[3]asapplicable.Theuseofshortrangedevices(SRD)isalsocoveredinCEPT/ERCRecommendation70-03[8].Itisrecommendedthatthespreadoftheminimumreceptionsensitivitybetweenallmanufactureddevicesinasystembekeptassmallaspossible.Thisisintheinterestsofminimizingdataclashesbetweencompetingsystems.6DescriptionoftheaccessprotocolAlldevicesfulfillingthepresentstandardshallusethisprotocoleachtimetheyaccesstheRFchannelandtheRFchannelistobeusedonlybysuchdevices.6.1ChannelaccessdurationThetotaltimeduringwhichthechannelmaybeoccupiedforeachaccess(channelaccessduration)shallnotexceedthedurationgiveninsubclause7.1.3.Thisincludesthedurationofanyacknowledgementorreplyfromarespondingdevice.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)10Providedthatboththemaximumdurationofchanneloccupation(channelaccessduration)andthereplycarrierdelaylimitsarefulfilled,thechannelmaybeoccupiedbyasequenceofanynumberoftransmissions(involving,possibly,repliesfromoneormoretransmitters).If,therefore,areplyingdevice,ordevicesarerequiredtoreturndata(e.g.forhandshakepurposes),thenthetimetakentodothisshallbeincludedinthechannelaccessduration.Transferoflargequantitiesofdatashallbeachievedbydividingitupintosuitablysmallpacketstosatisfythisprotocol.6.2PrinciplesForthepurposeofchannelaccess,theequipmentdetermineswhetherornotthechannelisfreeandhasbeenfreefortheobservationtimetobymeansofcarriersensinginthechannel.Theobservationtime(seesubclause6.5)consistsofafixedpart,aprioritypartandapseudo-randomadditionalpart.Whenthechannelappearstohavebeencontinuouslyfreebytheendoftheobservationtime,thetransmittermaybeinitiatedandshallbepoweredupwithinthespecifiedtime(theaccessingcarrierattacktimedelay,seesubclause7.7).Thepriorityparthasbeenincludedintheobservationtimeforthepurposeofgivingprioritytoshortermessagesinordertoimprovetheirresponsetimechances.ThetotaldurationoftheRFcarrieremission(accesstime)islimited(seesubclauses6.1and7.1).Theoveralldutycyclelimitationisgiveninsubclause6.7.Thenumberoftransmissionretries(intendedtoovercometransmissioncollisionsandcorruption)shouldbelimitedtoamaximumof5.6.3ProcedureInordertogainaccesstotheradiochanneltheequipmentshalldeterminewhetherornotthechannelis,andhasbeen,freeduringtheobservationtimet0,bymeansofcarriersensing(seesubclause6.4).Ifthechannelappearstobefreethroughouttheobservationtimeandthereisinformationtobesent,thetransmissionshallthenbeinitiatedandRFcarrierradiationcommencedwithinthespecifiedtime(carrierattacktime;seesubclause7.7.1fordefinition).Oncethechannelhasbeenseizeditmaybeoccupiedforuptothemaximumtimeallowedforasinglechanneloccupancy(seesubclauses6.1and7.1).Attheendofatransmission,anotherobservationtimemaystartimmediately,unlessthedutycyclelimithasbeenreached(subclause6.7).Ifare-transmissionisrequired(due,forexample,toa"collision"),thissameprocessshallberepeatedand,onceagain,thechannelshallbedetectedasbeingfreeduringtheobservationtimepriortorepeatingtheattempttotransmit.Toensurethatnootherusercanaccessthechannelduringahalfduplexaccess,amaximumReplycarrierdelaytchasbeendefined(seesubclause7.2).6.4CarriersensingCarriersensing,ormoreappropriatelychannelenergysensing,isthedetectionofwhethertheRFlevelinthereceivechannelexceedsagiventhresholdornot.ThecarriersenseshallbeabletodetectRFsignalswithdifferenttypesofmodulation(e.g.FSK,ASK,PSK,QAMetc.).Thechannelshallberegardedasinuseduringtheobservationtime(seesubclause6.5)iftheleveloftheRFsignalonthechannelexceedsthethresholdgiveninsubclause7.4.3.Carriersensingshalltakeplacethroughouttheobservationtimeeithercontinuouslyoratregularintervalsnotexceeding250µµµµsandthecarriersensedelayshallnotexceedthelimitgiveninsubclause7.5.3.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)116.5ObservationtimeTheobservationtimet0isthesumofthefixedparttf,thepriorityparttpandthepseudorandomparttr.t0=tf+tp+tr.Thefixedpart,tfoftheObservationtimeshallbenotlessthan5ms.Theprioritypart,tpoftheobservationtimeshallbenotlessthanthatgiveninthetableinsubclause6.6(0msto8ms).ThepseudorandomparttrshallconsistofarangeofNdifferentvaluesti.ThenumberNofthesedifferentvalues(ti)shallnotbelessthan11.Thedifferentvalues(ti)shallnotbelessthan1msofeachother.ThemeanofalltheseNvaluesshallnotbelessthan5ms.Thesmallestofthesedifferentvalues(ti)maybe0ms.AlloftheseNdifferentvalues(ti)shallbeusedinNsuccessivetransmissiontransactions.6.6MessageprioritydelayAprioritydelaytpshallbeincludedineachobservationtime.Thevalueusedfortpwillbeaccordingtothemessagelengthandisgivenintable1.Table1:MessageprioritydelaycategoriesCategoryDataPacketlengthPrioritydelaytpVeryshortnotgreaterthan12ms≥0msShortnotgreaterthan25ms≥2msNormalnotgreaterthan50ms≥5msLongnotgreaterthan100ms≥8ms6.7DutyCycleThedutycycleofdevicestransmittingmessagesshallbelimitedasgivenforcategory3indutycyclecategories,CEPT/ERCRecommendation70-03[8].DutycyclelimitationsareonlyprovidedinordertoavoidthatadeviceunabletoreceivecorrectlymayblockthechannelwithanunacceptableDutycycle.6.8AntiblockingInthecaseofinterference,thechannelmayappeartobeinconstantuse.Inaccordancewiththeprotocoldefinedsofar,allthedevicesshouldremainintheobservationstatusandthechannelwouldthenbe"blocked".Inordertoavoidtherealblockingofallthedevices,amechanismisprovidedtoallowalsoforchannelaccessinsuchconditions(seesubclause7.3).Thismechanismisoptional,however,thismechanismrequiresaminimumwaittimebeforechannelaccessisallowed.Underallcircumstances,thedutycyclelimitationgiveninsubclause6.7applies.SIST EN 301 391 V1.1.1:2003
ETSIETSIEN301391V1.1.1(2000-01)127MethodsofmeasurementandlimitsAspecialtestmodemaybeusedprovidedthatthenormaloperatingcharacteristicsarenotaffected.7.1Channelaccessduration7.1.1DefinitionThechannelaccessdurationisthetimeelapsedbetweentheinitialaccesscarrierreachingalevelofPmean–20dBandthepointatwhichthepowerfallstothesamelevelattheendofthetransmissionortheendofthereplyinthecaseofamultitransmittercommunication.Figure1:ChannelaccessdurationDeviceswhichareabletoinitiateatransmissionandaretransmittingwithoutresponsetoanypreviousinitialtransmissionfromotherdevicesshallalsobeconsideredforthismeasurement(seesubclause7.1.2.1).Amultitransmitterchannelaccessisoneinwhichseveraltransmittingdevicesaccessthechannelaspartofthesamemessagetransfer.Itconsistsofaninitiatingtransmissionfollowedbyoneorseveralsequentialreplyingtransmissions(seesubclause7.1.2.2).7.1.2MethodofmeasurementTwodifferentmeasurementsarerequiredtobeperformed.Themaximumchannelaccessdurationofadevicethatisabletoinitiateadatapackettransmission(singletransmitter,seesubclause7.1.2.1)shallbemeasured.Themaximumchannelaccessdurationforaninitiatingtransmissionfollowedbyalldevicescapableofreplyingwiththeirtransmissions(seesubclause7.1.2.2)shallalsobemeasured.7.1.2.1AsingletransmitteraccessingthechannelAmeasurementshallbemadeofthetimeelapsedbetweentheinstantwhenthecarrierreachesalevelofPmean-20dBandtheinstantwhenthecarrierfallstothesamelevelattheendofthetransmission.Seefigure1.ThedutycycleisrequiredtobemeasuredinconformancewithEN300220-1[1];EN300330[2]andI-ETS300440[3]asapplicable.PmeanPmean-20dB
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