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A. a.(1)(a) i) a)S#$%($0 ($0 0 (($0 0 0   A_ekqwDocumentDocument StyleI.1.A.a.(1)(a)i)a)x?t2PleadingHeader for Numbered Pleading Paper (  )(  XX66*'*d666*'*d6\l)1\l)2\l)3\l)4\l)5\l)6\l)7\l)8\l)9)10)11)12)13)14)15)16)17)18)19)20)21)22)23)24)25)26)27)28  .+(2t$ 5!  p4Heading 2Underlined Heading Flush LeftV4Heading 1Centered Heading@..  b* 8Bullet ListIndented Bullet List0..0` ..`   K85$  1    3\3\3\0` S"Table3.BitErrorProbabilitiesforBinaryOrthogonalSignaling,SlowNonselectivefading,and X NoncoherentDemodulator,"ReferenceDataforRadioEngineersSeventhEdition,H.W.SamsCo.,pg2423(showsBERforRayleigh,Ricianandnonfadedchannelsfor420(Eb/No)dB)(2t$ 5!  (2t$ 5!  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Ts8RCR,,XRq t7[C[fX[#?u9N,,YwK1C,,XYwTn5bCbXbT b%ChXI5+ c#CX?I d*qCqXq%ke1`C`YX`au f;lClXlSTg2YCY,,XYh/^C^,,/X^\i/PCP,,XP  ?j/TCT,,_XT[T k/PCP,,XPl7WCW,,XWm6RCR,,2XR{%$0C,,oX]?"^dxdd0dHHlllDDlH@ddH000HHHd00ddddddl``d,HdddȄH?ThQTUVWXYZ[\]^_`abcdefghijknJAZ"Arial Regular 5!  X % 4  XRS, % 1  @<5pm pm pmIEEE802.11  X @5Q (5802LANAccessMethodforWirelessPhysicalMedium>6*' xd> ( pXm X pm DATE: ` January29,1994 } % >6*' _ xd> O   AUTHOR: ` ChandosA.Rypinski, L   `  ` ChiefTechnicalOfficer` LACE,Inc.&]5Tel:+014153896659   ` 655RedwoodHighway#340{]5Fax:+014153896746   ` MillValley,CA94954USAk^Z5Em:rypinski@netcom.com   >6*' xd> ^   TITLE: 0` RECOMMENDATION:The2.4GHzPHYCan'tBeFrequency [  HoppingButCanBeDirectSequence ` !` ! >6*' {xd> k    SUMMARYLX\ X XpXm  h ThemainreasonswhytheFHPHYshouldnotbean802.11recognizedPHYare:607The1/1.4Mbpsgrosstransferrateisinadequateforcompetent802LANservices % requiringalowerrorratePHY.Theshortfallisfurtherincreasedbylossesfromexcessdeferral,unavoidedcontentionandinterferencefromlackofanareacoverageplan. !! 607TheFHPHYisinherentlyanarrowbandmodulation,whichinaRayleighfading _ environment,willhaveabiterrorratefloorthatmakesmandatorystrongforwarderrorcorrectionusingabout50%oftheavailablecapacity. !! 607ThereisnopossiblesatisfactoryPHYlevelchannelassessment(CA)function.Only A" energydetectionwithtimeweightingispotentiallyfastenough."Busylockout"orpureAlohaoperationfromhighdetectionthreshholdsarethepredictableconsequences. !! 607Theadvantageofasecondtryonanewfrequencyafterafailureonafirsttryissmall "{& ornonexistentbecauseoftheinherentlargetimedelaybeforethesecondtrycanbemadeandcompleted. !! 607ThechannelizationfeatureoftheFHPHYisrequiredforparallelcapacityincreaseand  & * forisolationofcontiguouscoverages.However,simultaneouslyusedchannelsatdifferentfrequenciesinthesamebandwillbe mixedineachtransmitterpower '", amplifier creatingspurioussignalsatmultiplesofthedifferencefrequenciesremoved (~#- fromthetransmittercarrierfrequency(fortransmitterswithoutaunilateralizationdeviceintheantennaport).Withnumbersofsimultaneouslyusedtransmittersinasmallarea,manyfalseindicationsofactivitywillresultfromtheseintermodulationproducts. !! (continued)  ,'2 607ThefrequencinghoppingPHYlayernowdefinedcannoteffectivelybeintegratedwith X aMAClayer,andevenassumingthatitcouldbe,willnotrenderafunctionallyresponsiveintegrationofpacketandconnectiontypeservicesoracommerciallyadequatepacketservicealone. !! 607Radiocost,batterydrainandsizearelessforasinglechannelPHY.{ #!! 607OnlyasinglechannelPHYwillenableextensionofthetraditional802philosophyof   maximizingpeaktransferratewithintheavailableradiospectrum. !! AmotiontoeliminatethisPHYfromfurtherconsiderationwillbeintroducedbythisCommitteeMemberatthecurrent802.11meeting.Theargumentsrelevanttothisquestionaregiveninbriefforminthebodyofthiscontribution. ff@=D:5RECOMMENDATION:  The2.4GHzPHYCan'tBeFrequencyHoppingButCanBeDirectSequence  k   TableofContentsf5Page  B  ARGUMENTS@;i. 1 > $  $0` 0 ` ` ` ` '  Given:!@;i. | %  !1$݌ , Ќ  802PLENARYISSUES@;i.)1 r $  $0` 0 ` ` ` ` '  PROFH:!@;i.M ] &  !1$݌  Ќ  $  $0` 0 ` ` ` ` '  RebuttalPROFH!@;i..  !1$݌ V Ќ  $  $\0` 0 ` ` ` ` '  CONFH!@;i.h &  !1$\݌ D Ќ  $  $00` 0 ` ` ` ` '  PRODSPHY!@;i.=*  !2$0݌  Ќ  JOINT802.11MAC/PHYISSUES@;i.22 (  $  $S0` 0 ` ` ` ` '  PROFH!@;i.G l &  !2$S݌ n! Ќ  $  $'0` 0 ` ` ` ` '  RebuttalPROFH:!@;i.&K/  !2$'݌ "\ Ќ  $  $0` 0 ` ` ` ` '  CONFH!@;i.h &  !3$݌ # Ќ  $  $0` 0 ` ` ` ` '  PRODS!@;i.G { &  !4$݌ @% Ќ  802.11PHYGROUPISSUES@;i..4 &.!  $  $0` 0 ` ` ` ` '  PROFH!@;i.G l &  !4$݌ 't"! Ќ  $  $0` 0 ` ` ` ` '  RebuttalPROFH:!@;i.&K/  !4$݌ )#" Ќ  $  $0` 0 ` ` ` ` '  CONFH!@;i. '  !5$݌ X*%# Ќ  $  $y0` 0 ` ` ` ` '  PRODS!@;i. ? %  !6$y݌ +F&$ Ќ  RECOMMENDATION@;i.%6  ,'%  R ff/  @F:5 Recommendation: X @{5The2.4GHzPHYCan'tBeFrequencyHoppingButCanBeDirectSequence ff@=5  ARGUMENTS Ԉ  Given:    d TheFHandtheDSPHYarebothdefinedacceptablebytheFCCin15.247foruseinthe2.4GHzISMband.ThepresentDSPHYwillprovidea1or1.4Mbpstransferratefromanoccupiedbandwidthof7580MHzoneMHZatatime,andtheproposedDSPHYwillusea22Mcpschippingratefora2Mbpstransferrate.ItisassumedthattheDSPHYcanbescaledtohigherratesandoccupiedbandwidthifusefulornecessary.Theofferedargumentsaresortedintogroups:1)802.11plenaryissues,2)jointMACPHYissues,and3)purePHYissues.@T<85  802PLENARYISSUES q"  b    PROFH "  Q 01.U  Theachievabletransferrateof1or1.4MbpsissufficientforusefulLANandvoice  services. !!   RebuttalPROFH% 0 #   1r.0Theminimumtransferrateforaduplexsinglestationwithintegratedserviceswas f arguedin802.9duringitsfirstyear.MajorCompaniesthoughtduplex2.048and2.56Mbpsweresufficient.AftertwoyearsofdiscussionandtheformationofahighratePHYsubgroup,therateschosenwere4.096and20.540Mbps.Ratesof1or1.4Mbps ! aresimplyunserviceableformixedLANandconnectiontypeservices. !! 0LANat1Mbpswasrecognizedin802.3as1Base5(AT&T"StarLAN),andithasdisappearedasaproduct.Similarly,PCNetat2.0Mbps(IBMandSytek)wasofferedwithoutmuchacceptanceafewyearsagowhenthethreshholdofusefulnesswasmuchlowerthannow. !! 0Thistransferrateistoolowforreasonablesupportofthetrueconnectiontypeservicesassociatedwithmultimediaandtelecomextendedapplications. !! 0Conclusion: "A1or1.4MbpsmediumtransferrateisnonresponsivetoIEEE802.11 }%%  FunctionalRequirementsforintegratedservices,andiscommerciallyinadequateforLANonlyproducts.ThisconclusionistrueforanerrorfreemediumbeforeconsideringtheuncertaintiesofradioandtheFHNBmodulationwhichgreatlyincreasetransferraterequirementsforagiventhroughput. !!   CONFH )  g*%% 2.0UTheFHPHYiscountertotraditionalLANvalueswhichemphasizeasinglehighrate +V&& mediumwithlowaverage/highpeaktrafficcapability.FHinherentlydividesan80MHzbandwidthintoanumberofparallel1MHz(lowrate)channelsused -((( simultaneously.Thepeakcapacityofeachchannelisfarbelowthepotentialofthe80MHzbandwidththesystemwilloccupy. !! 3.UTheFHPHYiscountertoclosedissuesand802.11FunctionalRequirements / Ѐa)0 ThechannelizationinthisPHYisinadequateforprovidingallsupportedservicesover u 100%ofacoveragearea. !! Ѐb)0ThechannelizationfunctioninthisPHYisuniqueallowableonlyinthetwohigherUSA   ISMbands.Itcannotbeusedinanyofthenarrower,new1.9GHzfrequencybands.ThisPHYwillprecludeacommonMACforotheravailableradiofrequencies. !!   PRODSPHY .   4.0UThesinglechannelPHYingeneral,andtheDSPHYinparticularareconsistentwith [  traditional802valueswhichemphasizemaximizationofpeaktransferrateandminimizationofaccessdelayandoccupancytime.Eachuserhasaccesstothetransferrateoftheentirebandwidthallocationratherthanafractionofit. !! 5.0URadiocost,batterydrainandsizearelessforasinglechannelPHY.\ !!  @ d 45  JOINT802.11MAC/PHYISSUES `0     PROFH 0 /  5.0UTheinterferenceresistancepropertiesofthisPHYaresuperiorbecauseifthereis v interferenceononeparticularfrequency,themessagemaybesuccessfullytransferredonanother. !! 6.0UByusingvariousrandompatternsforthehoppingsequence,differenthoppingsequences 6 maybeusedbydifferentgroupswithonlyoccasionalcollisions.Thedifferentsequencescanbeconsideredasvirtualchannelsusableforcontinuousareacoverage. !!   RebuttalPROFH 3 N  5r.0Given,thatiftheuseofafirstusedfrequencyisunsuccessful,thesecondusedfrequency  isthensuccessful;thenominaltimedelaybetweenopportunitieswillbeonehopdurationplusonechannelswitchingtime.Withpresentlychosenparameters,thisintervalisatleasta"superframe"durationof25millisecondsandmaybeahundredmillisecondsormore.Recoveryfromthesecondtransmission,ifitissuccessful,is #9 outsideofthetargettransferdelaylimits.z$"!! 0Theprobabilitythatthenextselectedchannelisfreeofinterferencedependsonthesumofthenumberofotherhoppingpatternsthatcoexistinthecoverageplusthedegreeofunrelatednarrowbanduseoftheband.Therewillbefrequentcasesofpotentialcollisiononretry,whichmustthenberesolvedbytheMACfunction. !! 0Ifitisassumedthattheactivepatternsareactuallyinuseasmallfractionofthetime,itispossibletoarguethatpatterncontentionisimprobable.However,thispossibilityshouldbeevaluatedwiththesystemoperatednearitsmaximumratedcapacity. Otherwisebreakdownmayoccuronlyattimesofpeaktraffic.y,!'%!! 0Withcurrentproposalsforhoppingpatterns,andwithoutcoordinationofdifferent hoppingpatterns,theprobabilityofchannelcontentionisquitehighwithallchannelsinuse. !! 0Thisiswithoutconsideringwhatmaybehappeningfromfurtherunrelatedinterferers.Usingconventionalnarrowbandmodulations,thesignaltointerferencerationecessaryforcapturebythestrongersignalconsideringfadingwillbeintherangeof1218dB.Thislargerequiredmarginreducestheprobabilitythatthestrongersignalwillbesuccessfulwhenthereisacollision. !! 0Conclusion: "Therecoverymechanismofusingretransmissionafteroneormore Z  frequencyhopsaddsunacceptabletimedelay,andeventhenisdecreasinglyusefulaschanneluseincreases.ThisformoferrorrecoveryisuniquetothisPHY.* !! 6r.0TheassumptionmightbethatthechannelizationcapabilitywithFHcanbeusedasa m  methodoffrequencyreuse.Theexistenceofachannelizedmediumisnotafrequencyreuseplan.Unorganizeduseofmultiplechannelsdoesnotassurethatallofanygivenbuildingareahascoverageandaccess.(ThisreasonalonemakestheFHPHYandDFWMACnonresponsiveto802.11FunctionalRequirements). !! 0Overlappingcoveragecanberesolvedbycapacitysharing,whetherorganizedorrandom.Unorganizedsystemscanalwaysoperateifunboundedtransferdelaysandreducedmediumutilizationareaccepted.Ifaworstcaseaccessdelayisadesignparameter,thereisconsiderableartinmaximizingcapacityforchannelizedsystems. !! 0Incellularterms,thereusefactorislikelytorequire36to200channelstocoveranareaswithoutagap.Anorganizedplangreatlyreducesthisnumber.IfunorganizedFHcanproduce25virtualchannels,theperformancewouldbequitepoorwithallofthemrunninginacommonarealikeonefloorofalargebuilding. !!   CONFH @  Y 7.0UAddingtheCAfunction(CarrierpresenceAssessment)toeitherthePHYorthe H associatedMACwillnotresultinanadequatesolution. !! 0Thefirsterroristhatchannelenergyobservedatastationreceiverisanunreliableindicatorofreceivingconditionsatadestinationstation.Theadvantageofenergydetectionisthatitisquicktoreachaconclusion.Addingrefinements,suchasadaptivereferencelevel,requirestimeweightedjudgementsand/ordependenceonmessagecontent. !! 0SomeproposalsrequiretheMACtoconsiderthecontentofreceivedmessagestoclassifythesourceorreceivedsignalsandappraisethefuturetimeuseofthechannel.Thisisanintractableproblem,whichwillcausetheMACtobeuniquetothisPHY.If '3"" thestationMACisrequiredtousemessagecontentasamodificationofthechannelidlefunctionforCSMA,thetimedelayintroducedwillbeunacceptable.IfthisfunctionisuniquetoFH,thechoiceofthePHYwillcausetheMACtobenonresponsivetoan802.11FunctionalRequirementthattheMACbeusablewithmultiplePHYs.)+%&!! 8.0USincesinglechannelPHYsareinevitable,theMACwillreallybetwoormoreMACs l,'' tocoverbothFHandsinglechannel.ThispartitioningisinadditiontotheMAC U-'( partitioningtohandlecontentionandreservationservices.Thedifficultyinobtainingafaultfreeprotocolcouldbeseriouslyunderestimated. !! 9.0UAddingthechannelpatternselectiontoaMAC,willassociatetheMACwithaparticular / methodoffrequencyreusemanagementnotparticularlyunderstoodorplannedintheDFWMAC.Properly,theMACshouldnotknowanythingaboutchannelpatternselectionexceptdistinguishingthataparticularreceivedsequenceis/is_notpartofthedefinedgroup.PlacingchannelselectioninthePHY,meansthatcoordinationwithotherchannelpatternstoprovideaDAMAfunctionisimpossible. !!   PRODS I  Z  10.0DSisasinglechannelPHY.AllsuchPHYsareinterchangeablewithacommonMAC. I  TheneedforchannelpatternandselectionintheMACisavoided. !! 11.0Ifused,theenergyformoftheCAfunctionwithDSislessvulnerabletofalse x  indicationsthanwithFHsinceitmaydetectenergyinboththeradioandinformationbandwidthandsincethesignaltointerferenceratiorequiredislower.. !! 12.0TheDSPHYcanbemultipliedtohighertransferratesbysimplescalinguntilthe  availablebandwidthisusedandfurtherbyincreasedsymbolcoding.ThepresentandpotentialpeaktransferrateisoctavesabovethatoftheFHPHY. !!  @d=65  802.11PHYGROUPISSUES 2MԈ  PROFH iM  6 13.0ThealternativeDSPHYhasbeentriedandfoundunsatisfactorybysomesuppliers, } thoughitisoneofthetwocurrentlyacceptedcandidatePHYsfor802.11. !! 14.0Thenecessarycomponentsforfrequencysynthesis,narrowbandmodulation,  amplificationanddemodulationalreadyexistusingwellknownand"safe"technology. !!   RebuttalPROFH ^O  3 13r.0 TheunacceptableDSPHYshavegenerallyusedmethodswherethereceiveroutputis z " logiclevelatthechiprate,andwithcorrelatorsimplementedasbinarylogic.Thenthe c!  threshholdnoisebandwidthandinterferencesusceptibilityisthebandwidthofthechippingrate.Theprocessinggainisnotobtainedagainstinterferencestrongenough 3# todegradetheradiochiprateoutput. !! 0Thesedisadvantagesarenotpresentifthecorrelatorislinearandanalogoperatedatalevelof3050dbabovethatreceivedfromtheantennaand60dBbelowlogiclevel.Forthisdefinition,thenoisebandwidthoftheinformationisobtainedatcorrelation,anditismaintainedforinterferencestrongerthanthesignalwhichdoesnotdrivethecorrelatoroutofitslinearrange. !! 0Withlinearcorrelationatminimallevelabovethenoisethreshold,thenoisebandwidth L*$# ofthereceiversystemwillbethatofthetransferredinformation.Thisratioistrueforcomparisonswhenequalchannelmodulationsareusedfornarrowbandandforchipping.-'&!! 14r.0 Experiencesuggeststhatanewvolumemarketwilldevelopitsowncomponentsusing X knowledge,butnotthepieces,ofthepriorart.TheconstraintsofpriorartbuiltintoStandardsmaypreventeconomicalsolutions.Theimportanceofexistingpartsisgreatforthosewhowanttogotomarketimmediately,butbuildingaStandardaroundthesepartscanbeveryunfortunateforthefunctionalvalueoftheresultingequipment. !!   CONFH rV  B  15.0ThenarrowbandmodulationsproposedforFHwillhaveanexcessiveerrorratefrom  1 timedispersionatsignallevelsfarabovethreshhold.. N%  1      ׀Generally,forwarderror r  correctingcodesandahigherorderofreceiverspacediversityisrequiredtoobtainsatisfactoryerrorrates. !! 0Anarrowbandmodulation,particularlyoneusingquadraturephase,willrequireconsiderableoverheadinchannelcoding,O N%  2      ׀protocol,bufferingofdelayedtransmissions s  andanalogradiocostrelativetoDSwithappropriatepropertiesyieldinggreaterfaderesistance. !! 0ThesamenarrowbandmodulationisequallywellappliedtothechippingrateoftheDSsystemforthesameincentives.TheuseofDSwillenablegreatlyreducedpreamblelengthbydeletingpatterndiscoveryconsiderationsandbyenablingmuchfasterbitand ] framedelimitingacquisition.F!! 16.0Intermodulationinsimultaneouslyusedtransmittersisamajorcauseofspuroussignals 4 whenmanytransmittersaredenselypacked.Thepotentialforcrowdingofdifferenthoppingpatternsinacommoncoverageareaisoverestimated,particularlywhentheCAfunctionusesenergydetection.Eachactivetransmitterconnectedtoanantennageneratesspurioussignalsatmultiplesofthedifferencesbetweenthetransmittercarrierandreceivedsignals.UnlessacirculatorisinterposedbetweentheantennaandaclassCpoweramplifier,thatamplifieractslikealowlossmixerusingthetransmittedsignalasalocaloscillatorforcombiningwithstrongreceivedsignals.TheremodulatedandreradiatedsignalswillfurtherconfusebothenergyandcontentdecodingCAfunctions. !! 17.0Thetimelosttooverheadforpatternandbitclockacquisitioninadversecontextandfor   delayinchannelchangingisasignificantdegradationofthechannelpotential. !!   PRODS _  I" 18.0DirectsequencespreadingisasinglechannelPHY.Thespreadingreducestheeffects #8 offadingincludingtheratioofdesired/undesiredsignallevelforcorrectdemodulationofcochannelsignals.Withlineardecorrelationatthereceiver,thenoisebandwidthwill closertothatoftheinformationthanwiththesimplernarrowbandradios.K& !!! 0Providedthataninterferingsignalisnotstrongenoughtoexceedthelinearrangeofthe correlatoranditsenergycontentislessthan3dBabovethedesiredsignal,itisunlikelytocausematerialimpairment.Certainclevercircuitsmayincreasethisdiscriminationforsignalsofunlikespectrum. !! 19.0BitclockacquisitionwithDSmaybeaccuratelyperformedinafewbitsratherthana Y  muchlongerpartofthe100bitsprovidedforthepreambleinFH. !! 20.0RadiocostisprobablylowerthanforFHPHY.Muchofradiocostisduetoprecision  0 offiltersandfrequencycontrolelements,afunctionoffractionalbandwidth.Aradiowithachannelbandwidthof25MHzmaybe25timeslessprecisethanonewithabandwidthof1MHz.Thehighbandwidthradiowillhave14dBlessoverallgainwhichshowsindiminishedshieldingandbypassingfunction. !! 21.0Aradiothatmustoperateatthesametimeinthesamespaceasmanyotherliketype r  radiosmusthavemuchmoredynamicrangeandhigheroverloadpointsthanthealternativesinglechannelradio.Theradiosinonespaceoperatesequentiallyatamuchhigherrateandlowerchanneltimeoccupancy.Forasinglechannelradio,theoverloadconsiderationsarebasednotonotheruserswithinthesamegroupbutonmoredistantunrelatedusers. !! 22.0Channelizedsystemscannotgobothways.Thecapacityadvantageshowninprevious E comparisonsresultsfromusingmostofthechannelsatthesametime.Ifitisarguedthatthesimultaneoususeisimprobable,orifitistechnicallyunfeasible,thepapercapacity  advantageofFHshrinkstoadisadvantage.!! @_i:5  RECOMMENDATION i  1 0Aradiowithoutchannelizationisthesimpler,moreeconomicalandthehighestcapacity x andfunctionality.Withasinglechannelradio,thetimesharingcanbebettermanagedwhetherdonewithlogicorwithanalogenergymeasurements. !! 0TheFHPHYrequiresaMACthatisspecifictothisPHYandmuchmorecomplexthan  necessary,andwhichwouldnotbeusedinanyothercircumstance. !! 0ThePHYmustbesinglechanneltohaveanygenerality,anditshouldbedesignedfor " thehighestpossibletransferrate.AminimumbeingascalingofthepresentproposedDSPHYto4Mbps. !! PassageofamotionterminatingfurthereffortoftheFHPHYandexpandingeffortontheDSPHYinthecontextofthe2.4GHzbandwouldbring802.11closertosomethingwhichwillmeettheneedsofbothusersandmostsuppliers.ChandosA.Rypinski,votingmember