數(shù)據(jù)采集與傳輸系統(tǒng)軟件設(shè)計(jì)

#ORG1200HMOVD_OUT,#93HLCALLSEND1LCALLRECEIMOVMOVD_OUT,#93HLCALLSEND1LCALLRECEIMOVA,DA_INMOVJIANZ,AJIANC:SUBBA,#03JCJIA02CPLBTWEIJBBTWEI,QUFANMOVTH2,#0FFHMOVTL2,#0E9HMOVRCAP2H,#0FFHMOVRCAP2L,#0E9HSJMPJIENDQUFAN:MOVTH2,#0FFHMOVTL2,#0EBHMOVRCAP2H,#0FFHMOVRCAP2L,#0EBHSJMPJIENDJIA02:MOVA,JIANZSUBBA,#02JCJIA01DECTODAOSJMPJIENDJIA01:MOVA,JIANZSUBBA,#01JCJIA00INCTODAOSJMPJIENDKEYZH:PUSHAJIA00:CPLZHWEIJIEND:POPA讀鍵值鎖存器指令（地址讀出鍵值保存鍵值健值處理程序,判斷波特率變換位裝入16KBPS初始值裝入18KBPS初始值取鍵值通道號減1取鍵值通道號加1循環(huán)/單路顯示變換13H)RETIEND接收端應(yīng)用程序：TOC\o"1-5"\h\z波特率變換控制位:01H串口接收緩沖區(qū)：61H-6FH（共十五個）顯示通道號字節(jié)地址:71H數(shù)據(jù)緩沖區(qū):72H,73H,74H,75H（高位在前）顯示發(fā)送計(jì)數(shù)器:76H鍵盤值暫存:77H串口接收計(jì)數(shù)器:78H從7281A接收暫存:21H向7281A發(fā)送暫存:22H

BTWEIBIT01HTODAODATD071HQIANWDATA072HBAIWEDATA073HSHIWEDATA074HGEWEIDATA075HBITCTDATA076HCHUJIDATA078HDA_INDATA021HD_OUTDATA022HCLKBITP1.1;7281A通訊口DATBITP1.0CLRA;數(shù)據(jù)區(qū)清零MOVR0,#61HMOVR2,#01FHMOV@R0,ADJNZR2,XUNHUMOVSP,#2FH;設(shè)置堆棧SETBEA;CPU開放中斷SETBEX0;允許外部中斷0中斷SETBIT0;設(shè)置外部中斷0為邊緣觸發(fā)SETBESMOVIP,#10H;設(shè)串行口中斷優(yōu)先級最高M(jìn)OVSCON,#70H;串行口工作于方式1接收MOVT2CON,#34H;啟動定時計(jì)數(shù)器2，發(fā)送波MOVTH2,#0FFH;裝入初始值MOVTL2,#0E9HMOVRCAP2H,#0FFHMOVRCAP2L,#0E9H;以上為系統(tǒng)初始化MOVCHUJI,#15;串口接收數(shù)據(jù)計(jì)數(shù)器置初值MOVD_OUT,#12H;BC7281初始化波特率變換控制位置0，16kbpsXUNHU:ORG0000HLJMPSTARTORG0003HLJMPORG0000HLJMPSTARTORG0003HLJMPKEYZH;鍵盤中斷ORG0023HLJMPCHUAN;串口中斷ORG100HBTWEISTART:CLRLCALLMOVLCALLXIANS:MOVLCALLSEND1D_OUT,#80HSEND1D_OUT,#14HSEND1設(shè)定為164模式，不反相發(fā)送BCD譯碼指令MOVA,TODAO;發(fā)送通道號ORLA,#00H;在第0位顯示ORG200HORG200HSEND1:CLRCLKSETBCLKWAIT1:JBDAT,SEND1CLRCLKSETBCLKWAIT2:JNBDAT,WAIT2MOVBITCT,#8SLOOP:MOVC,D_OUT.7MOVDAT,CCLRCLKSETBCLKMOVA,D_OUTRLAMOVD_OUT,ANOPNOPNOPDJNZBITCT,SLOOPSETBDATMOVD_OUT,ALCALLSEND1MOVD_OUT,#14H;發(fā)送BCD譯碼指令LCALLSEND1MOVA,QIANW;發(fā)送千位數(shù)值ORLA,#10H;在第1位顯示MOVD_OUT,ALCALLSEND1MOVD_OUT,#14H;發(fā)送BCD譯碼指令LCALLSEND1MOVA,BAIWE;發(fā)送百位數(shù)值ORLA,#20H;在第2位顯示MOVD_OUT,ALCALLSEND1MOVD_OUT,#14H;發(fā)送BCD譯碼指令LCALLSEND1MOVA,SHIWE;發(fā)送十位數(shù)值ORLA,#30H;在第3位顯示MOVD_OUT,ALCALLSEND1MOVD_OUT,#14H;發(fā)送BCD譯碼指令LCALLSEND1MOVA,GEWEI;發(fā)送個位數(shù)值ORLA,#40H;在第4位顯示MOVD_OUT,ALCALLSEND1SJMPXIANS;向7281發(fā)送一個字節(jié)子程序;輸出CLK脈沖;檢測DAT如為高繼續(xù)輸出脈沖;15US之內(nèi)再輸出一CLK脈沖;等待DAT恢復(fù)高電平（輸入狀態(tài)）;輸出BIT7;輸出一CLK脈沖;D_OUT左移一位;短暫延時;恢復(fù)DAT為高電平

NOPNOPNOPNOPRETORG250HRECEI:CLRCLKSETBCLKWAIT3:JBDAT,WAIT3CLRCLKSETBCLKMOVBITCT,#8RLOOP:NOPNOPNOPNOPNOPNOPNOPNOPNOPMOVA,DA_INMOVC,DATRLCAMOVDA_IN,ACLRCLKSETBCLKDJNZBITCT,RLOOPCLRCLKSETBCLKNOPNOPNOPNOPRETORG300HKEYZH:PUSHAMOVD_OUT,#93HLCALLSEND1LCALLRECEICPLBTWEIJBBTWEI,QUFANMOVTH2,#0FFHMOVTL2,#0E9HMOVRCAP2H,#0FFH指令間設(shè)置一微小延時從7281接收一個字節(jié)子程序發(fā)出一單一CLK指令間設(shè)置一微小延時從7281接收一個字節(jié)子程序發(fā)出一單一CLK脈沖等待DAT低電平響應(yīng)信號再發(fā)出一CLK脈沖，準(zhǔn)備接收數(shù)據(jù)短暫延時讀入一位發(fā)出CLK脈沖發(fā)出CLK脈沖指令間增加一微小延時讀鍵值鎖存器指令（地址13H）讀出鍵值波特率變換位裝入16KBPS初始值SJMPJIEND裝入18KBPS裝入18KBPS初始值串口接收數(shù)據(jù)中斷程序判斷接收的數(shù)據(jù)序號數(shù)調(diào)接收子程序MOVTL2,#0EBHMOVRCAP2H,#0FFHMOVRCAP2L,#0EBHJIEND:POPARETIORG400HCHUAN:PUSHAMOVA,CHUJISUBBA,#15JCCHU14LCALLRXSUBMOV61H,ADECCHUJIAJMPRXENDCHU14:MOVA,CHUJISUBBA,#14JCCHU13LCALLRXSUBMOV62H,ADECCHUJIAJMPRXENDCHU13:MOVA,CHUJISUBBA,#13JCCHU12LCALLRXSUBMOV63H,ADECCHUJIAJMPRXENDCHU12:MOVA,CHUJISUBBA,#12JCCHU11LCALLRXSUBMOV64H,ADECCHUJIAJMPRXENDCHU11:MOVA,CHUJISUBBA,#11JCCHU10LCALLRXSUBMOV65H,ADECCHUJIAJMPRXENDCHU10:MOVA,CHUJISUBBA,#10JCCHU09LCALLRXSUBMOV66H,ADECCHUJIAJMPRXENDCHU09:MOVA,CHUJISUBBA,#09JCCHU08LCALLRXSUBMOV67H,ADECCHUJIAJMPRXENDCHU08:MOVA,CHUJISUBBA,#08JCCHU07LCALLRXSUBMOV68H,ADECCHUJIAJMPRXENDCHU07:MOVA,CHUJISUBBA,#07JCCHU06LCALLRXSUBMOV69H,ADECCHUJIAJMPRXENDCHU06:MOVA,CHUJISUBBA,#06JCCHU05LCALLRXSUBMOV6AH,ADECCHUJIAJMPRXENDCHU05:MOVA,CHUJISUBBA,#05JCCHU04LCALLRXSUBMOV6BH,ADECCHUJIAJMPRXENDCHU04:MOVA,CHUJISUBBA,#04JCCHU03LCALLRXSUBMOV6CH,ADECCHUJIAJMPRXENDCHU03:MOVA,CHUJISUBBA,#03JCCHU02LCALLRXSUBMOV6DH,ADECCHUJIAJMPRXENDCHU02:MOVA,CHUJISUBBA,#02JCCHU01LCALLRXSUBMOV6EH,ADECCHUJIAJMPRXENDCHU01:LCALLRXSUBMOV6FH,AMOVCHUJI,#15RXEND:MOVR3,61HMOVR4,62HMOVR5,63HLCALLRXCHUMOVTODAO,AMOVR3,64HMOVR4,65HMOVR5,66HLCALLRXCHUMOVQIANW,AMOVR3,67HMOVR4,68HMOVR5,69HLCALLRXCHUMOVBAIWE,AMOVR3,6AHMOVR4,6BHMOVR5,6CHLCALLRXCHUMOVSHIWE,AMOVR3,6DHMOVR4,6EHMOVR5,6FHLCALLRXCHUMOVGEWEI,APOPARETI調(diào)接收數(shù)據(jù)處理程序通道號調(diào)接收數(shù)據(jù)處理程序千位數(shù)調(diào)接收數(shù)據(jù)處理程序百位數(shù)調(diào)接收數(shù)據(jù)處理程序十位數(shù)調(diào)接收數(shù)據(jù)處理程序個位數(shù)RXSUB:CLRRIMOVA,SBUF;接收數(shù)據(jù)JBPSW.0ERERR;奇偶出錯判斷MOVC,ACC.7ORG500HORG520HORG520HRXCHU:MOVA,R3JBACC.7,RX002SUBBA,R4JNZRX001MOVA,R3SJMPENDRXRX001:MOVA,R3SUBBA,R5JNZRX002MOVA,R3SJMPENDRXRX002:MOVA,R4JBACC.7,RX003SUBBA,R5JNZRX003MOVA,R4SJMPENDRXRX003:MOVA,#0AHENDRX:RETENDJNCRXCUNCPLACC.7SJMPRXCUNERERR:MOVA,#80HRXCUN:RET出錯，置A為80接收數(shù)據(jù)處理程序兩數(shù)相等，有效兩數(shù)相等，有效兩數(shù)相等，有效兩兩不等，無效外文資料翻譯原文:TheCDMARevolution原文:ThegreatattractionofCDMAtechnologyfromthebeginninghasbeenthepromiseofextraordinarycapacityincreaseovernarrowbandmultipleaccesswirelesstechnologies.Simplemodelssuggestthatthecapacityimprovementmaybemorethan20timesthatoftheexistingnarrowbandcellularstandards,suchasAMPSinNorthAmerica,NMTinScandinavia,TACSintheUnitedKingdom.Historically,thecapacitywascalculatedusingsimplearguments.Reality,ofcourse,ismuchmorecomplicatedthantheidealizedmodels.Realcellcoverageareasarehighlyirregular,nottheneathexagonsfoundintextbookmodels.Offeredloadisnotspatiallyuniform,changesdramaticallywithtime-of-day,andisoftensubjecttootheruncontrollableinfluences.BackgroundAnidealizedmultipleaccessmobileradiosystemconsistsofafamilyofbasestations,or"cells,"geographicallydistributedovertheservicearea,andmobilestations.Weusetheterm"mobile"genericallytomeananysubscriberstation,whetheritmovesornot.Themajorityofnewcellularsalesarenowinfacthandheldportableunits,andthemarketoutlookisforthattrendtocontinuefortheforeseeablefuture.Non-traditionaluses,suchaswirelessdatamodemsinlaptops,arealsoexpectedtogrowdramaticallyinthenearfuture.Spectrumformobilewirelessisnormallyallocatedinfrequencydivisionduplex(FDD)pairedbands.Cellularsystemsareseparatedby45MHz,PCSbandsby80MHz.Althoughtherehavebeensomeproposalsfortheuseoftimedivisionduplex(TDD),suchoperationinherentlylimitsthecoveragearea,andhavenotachievedwidespreadacceptance.Communicationbetweenbasestationsandmobilestationsisestablishedbyanegotiationuponcallorigination.Oncecommunicationisestablishedbetweenbaseandmobile,movementofthemobileisdetectedandtheserviceishandedoverfromonebasestationtoanother.Onecellatatimeserviceseachmobileinthenarrowbandservices.Theconceptofhandoffisextendedtoamulti-waysimultaneous"soft"handoffintheCDMAstandards.WhencellularradiowasfirstproposedbyBellTelephoneLaboratories,cellsubdivisionwascitedasthemethodbywhichthesystemwouldgrowintrafficcapacity.Howeverthemarketplacesuccessofcellularhasoutstrippedpredictionsbysuchalargemarginthatsubdivisionofcellstoincreasecapacity,asapracticalmatter,islosingeffectiveness.AMPSmobileshaveaverylimitedabilitytoreducetransmitterpower.Highdensity,smallcellsalsoincreasethehandoverrate,therebyincreasingtheprobabilitythatanyparticularcallwillbedropped.Theoverheadcostsassociatedwithlargenumbersofcells,suchasrealestate,backhauls,andmaintenance,becomeaneverlargerfractionofcapitalandoperatingcosts.Zoningboardsincreasinglyresistapplicationsfornewantennatowersthatmaketheirjurisdictionsresembleoildrillingfields.Analternativemethodofcapacityenhancementwasneeded.TraditionalMultipleAccessCommunicationTraditionallyradiocommunicationsystemshaveseparatedusersbyeitherfrequencychannels,timeslots,orboth.Theseconceptsdatefromtheearliestdaysofradio.Evensparktransmittersusedresonantcircuitstonarrowthespectrumoftheirradiation.Schedulednetoperationwasprobablythefirstmanifestationoftimeslotting.ModerncellularsystemsbeganwiththeuseofchannelizedanalogFM.MorerecentlyseveralhybridFDM-TDMdigitalsystemshavebeendeveloped,ostensiblytoenhanceservicequalityandcapacity.Inallthesesystems,eachuserisassignedaparticulartime-frequencyslot.Inlargesystemstheassignmentstothetime-frequencyslotscannotbeunique.Slotsmustbereusedinmultiplecellsinordertocoverlargeserviceareas.Satisfactoryperformanceinthesesystemsdependscriticallyoncontrolofthemutualinterferencearisingfromthereuse.Thereuseconceptisfamiliarevenintelevisionbroadcasting,wherechannelsarenotreusedinadjacentcities.NorthAmericancellularallocatesapproximatelyAMPS416channelstoeachoperator(30kHzspacing,withatotalallocationof12.5MHzineachdirection-seetheFrequencyPlan).Anidealizedsystemgeometryshowninthefigure.Thesamefrequencyobviouslycannotbereusedinanyadjacentpairofcellsbecauseauserontheboundarybetweenthosecellswouldreceivebothsignalswithequalamplitude,leadingtoanunacceptablyhighinterferencelevel.Aplanecanbetiledwithhexagonalcells,labeledinaccordancewiththeseven-waypatternshowninthefigure.Thus,ifauniquesetofchannelsisassignedtoeachofthesevencells,thenthepatterncanberepeatedwithoutviolatingtheadjacencyrequirement.Althoughthisidealizedpatternisnotstrictlyapplicableinallrealsystems,theseven-wayreusepatternisapproximatelycorrect.Thecapacityofsystemsbuiltinthiswayisdeterminedbythebandwidthperchannelandtheseven-wayreusepattern.InanAMPSsystem,therefore,themaximumcapacitypercellisapproximately416/7=59.Forthree-waysectoredcells,thesameK=7reuseappliesoverallthreesectors,thatis,onlyabout19channelsareavailableineachsector.Inanidealgeometrythereusepatternlookslikethis,representingchannelsetsbydistinctcolorsInthisconnection,itshouldbenotedthatachievementoftheK=7reuse,ratherthananevenlargernumber,dependsonthefactthattheeffectivepropagationdecaylawisfasterthanfreespace.Thatis,inavacuumelectromagneticradiationdecaysinintensitylikeR-2.Howevermeasurementshaveconsistentlyshownthattheeffectivepropagationlawexponentistypicallybetween-3.5and-5inthegroundmobileenvironment.Interestingly,itiseasytoshowthatifthepropagationlawwerethatoffreespace,alargecellularsystemwouldnotbeviableatall.Thelarger-than-free-spacepropagationexponentmeansthatonlythefirsttierofneighborcellsissignificantintheidealizedmodel.The"Magic"ofCDMACDMAoffersananswertothecapacityproblem.Thekeytoitshighcapacityistheuseofnoise-likecarrierwaves,aswasfirstsuggesteddecadesagobyClaudeShannon.Insteadofpartitioningeitherspectrumortimeintodisjoint"slots"eachuserisassignedadifferentinstanceofthenoisecarrier.Whilethosewaveformsarenotrigorouslyorthogonal,theyarenearlyso.Practicalapplicationofthisprinciplehasalwaysuseddigitallygeneratedpseudo-noise,ratherthantruethermalnoise.Thebasicbenefitsarepreserved,andthetransmittersandreceiversaresimplifiedbecauselargeportionscanbeimplementedusinghighdensitydigitaldevices.Themajorbenefitofnoise-likecarriersisthatthesystemsensitivitytointerferenceisfundamentallyaltered.Traditionaltimeorfrequencyslottedsystemsmustbedesignedwithareuseratiothatsatisfiestheworst-caseinterferencescenario,butonlyasmallfractionoftheusersactuallyexperiencethatworst-case.Useofnoise-likecarriers,withallusersoccupyingthesamespectrum,makestheeffectivenoisethesumofallother-usersignals.Thereceivercorrelatesitsinputwiththedesirednoisecarrier,enhancingthesignaltonoiseratioatthedetector.TheenhancementovercomesthesummednoiseenoughtoprovideanadequateSNRatthedetector.Becausetheinterferenceissummed,thesystemisnolongersensitivetoworst-caseinterference,butrathertoaverageinterference.Frequencyreuseisuniversal,thatis,multipleusersutilizeeachCDMAcarrierfrequency...Thereusepatternisnow

Therainbowcellsindicatethattheentire1.25MHzpassbandisusedbyeachuser,andthatsamepassbandisreusedineachcell.CapacityisdeterminedbythebalancebetweentherequiredSNRforeachuser,andthespreadspectrumprocessinggain.Thefigureofmeritofawell-designeddigitalreceiveristhedimensionlesssignal-to-noiseratio(SNR)EnergyperbitPowerspec杼威densityofnaise+(])The"noise"partoftheSNR,inaspreadspectrumsystemisactuallythesumofthermalnoiseandtheother-userinterference.TheSNRneededtoachieveaparticularerrorratedependsonseveralfactors,suchastheforwarderrorcorrectioncodingused,andthemultipathandfadingenvironment.ForthereceiverstypicallyusedincommercialCDMAitrangestypicallyfromabout3dBto9dB.Energyperbitisrelatedtosignalpoweranddatarate:爲(wèi)=緜⑵Thenoise+interferencetermispowerspectraldensity.Ifthespectrumofthesignalsisroughlyrectangular,withabandwidthofW,thenthenoise+interferencepowerspectraldensityis%=FNkBT.+曠工§0攪百尸卍朕磐(3)wherethefirsttermrepresentsthethermalnoiselevelofthereceiver(FN=receivernoisefigure).RewritingtheSNRequationintermsofthedatarateandthespread-spectrumbandwidthshowswherethemagiclies:Theinterferenceinthisequationisthesumofthesignalsfromallusersotherthantheoneofinterest.ThisequationisthekeytounderstandingwhyCDMAwasnotexploredforuseinterrestrialmultipleaccesssystems.ItisalsothekeytotheinnovationthatledtocommercialCDMA.VoiceCodingBecausetheinterferenceisaveraged,anythingthatcanbedonetoreducetheaveragetransmittedpowerenhancescapacity.Anobvioustargetforsuchpoweroptimizationisthespeechcoding.Humanspeechisanintermittentinformationsource.MeasurementsatBellLaboratoriesmanyyearsagosuggestedthattheactivityfactorinnaturalhumanconversationisintherangeof35-40%.Ifthatactivityfactorcanbetranslatedintopowergating,thenafurtherincreaseincapacityofperhapstwotimesormoreispossible.Thisisinfactaccomplishedbyfeaturesinboththeairinterfacestandardsandthevoicecoderserviceoptionstandards.wherevisthevoiceactivityfactor,approximately0.5.Thereductionachievedinpracticeislessthanthemeasuredactivityfactorbecausethetransmissionrateintheairinterfaceisnotreducedtozeroduringidleperiods.ThegainoverAMPScapacity,bythesameassumptionsasabove,isnowabout26times-perhapsoptimisticgiventhecrudenatureofthemodel,butsuggestiveofthesubstantialimprovementspossiblebyconvertingtoCDMA.Variableratedataisaccommodatedintheairinterfacebyprovidingabasictrafficdataratethatcanbereducedbybinaryratios(1,1/2,1/4,and1/8).Transmissionisneverreducedtozerobecausethiswouldpresentproblemsrelatedtochannelsupervision.Tworatefamiliesarecurrentlysupported:thefirstbasedon9600bps,thesecondon14,400bps.These,ofcourse,havedifferentcapacitycharacteristics.ThevoicecodingusedinCDMAisstandardizedseparatelyfromtheairinterfaceasaserviceoption.ThefirstcoderstandardizedwasIS-96;othersareinwidespreadused,andwillalsosoonbestandardized.TheIS-96standardoperatesinthenominal9600bpsrateset,andachievesanaverageeffectiverateofsomethingjustover4kbps,orabout50%oftheactualairinterfacepayloaddatarateof8550bps.CoverageversusCapacityThereissomebadnewsarisingfromtheCDMAcapacityequation.Namely,thefactthatthepowerthatthemobilesarerequiredtotransmitgoestoinfinityasthecapacitypoleisapproached.Astherequiredpowerincreases,mobilesatthefringeofcoveragewillbegintorunoutoftransmitterpower.Thatis,theywillbeaskedtotransmitmorethantheircapabilityallows.Thepracticalconsequenceofthisisthatthesystemloadshouldreallybecontrolledsothattheplannedserviceareaneverexperiencescoveragefailuresbecauseofthisphenomenon.Therearesomeinterestingmathematicalmodelsofthis,thatwetalkaboutinourCoverage-Capacitypages.Itisnotreallysomuchaproblemasitisasystemdesignconsideration.Youcannotsimultaneouslyachievemaximumcapacityandmaximumcoverage.Itisatradeoff.譯文：CDMA革命CDMA技術(shù)的巨大吸引力從一開始是承諾的非凡的容量增量窄頻帶接入無線技術(shù)

的能力，簡單的模型表明，提高能力可超過現(xiàn)有的窄帶蜂窩標(biāo)準(zhǔn)20倍，例如AMPS在北美,NMT在Scandinavia,TACS在英國。歷史上,容量計(jì)算采用簡單的論據(jù)?，F(xiàn)實(shí)中,當(dāng)然比理想化的模型復(fù)雜得多。真正的信元覆蓋區(qū)域是高度不規(guī)則的，不是勻整的合乎教科書規(guī)范的六角形。負(fù)載不是均勻空間，每時每刻都在急劇變化，而且常常受其他不可控因素影響。背景理想化的無線接入系統(tǒng)由多個家庭基站或"信元"，按地理分布的服務(wù)領(lǐng)域和流動站組成。我們所使用的"移動"一般用來指任何用戶站，無論移動與否。大多數(shù)新信元的銷售額其實(shí)是手提單位而且市場前景繼續(xù)看好，非傳統(tǒng)的用途，如無線數(shù)據(jù)調(diào)制解調(diào)器的膝上型電腦，也可望在不久的將來急劇增長。頻譜移動無線通常會分配在頻分雙工（FDD）1610階。蜂窩系統(tǒng)被分離45兆赫，電腦波段為80兆赫，盡管有過一些建議，使用時分雙工（TDD）這種運(yùn)作在限制的范圍，但并沒有被廣泛接受。溝通基站和移動站建立了一個協(xié)議后呼吁起源。一旦基地和移動單元之間建立通信，運(yùn)動中的移動單元檢測和發(fā)送數(shù)據(jù)從一個基站到另一個。一個信元通過窄頻服務(wù)同時發(fā)送給每一個移動單元。在CDMA標(biāo)準(zhǔn)中，切換的概念擴(kuò)展到多路同步的"軟〃切換。當(dāng)蜂窩移動通信最早由貝爾電話實(shí)驗(yàn)室提出時，分割信元被作為增加系統(tǒng)交通容量的方法。然而市場上的成功蜂窩已超過預(yù)測的幅度，細(xì)分信元提高系統(tǒng)能力，作為一個實(shí)際問題，正在失去效力。AMPSmobiles降低發(fā)射機(jī)功率的能力十分有限。高密度，小細(xì)胞也能增加移交率，從而增加某個電話被漏掉的幾率。間接相關(guān)的費(fèi)用與大量的信元，如房地產(chǎn)、回程運(yùn)費(fèi)、維修、成為資本和經(jīng)營成本有史以來較大的比例。分區(qū)制委員會也越來越抵抗他們的類似石油鉆井的新天線塔的申請。另一種可供選擇的提高容量的方法是需要的。傳統(tǒng)多址通信傳統(tǒng)無線電通信系統(tǒng)已經(jīng)分離，用戶無論頻道、時段，或兩者兼而有之。這些觀

念，從最早日期的無線電至今，甚至閃爍發(fā)報(bào)機(jī)采用諧振電路窄譜的輻射。預(yù)定網(wǎng)運(yùn)行恐怕是第一次表現(xiàn)。現(xiàn)代移動電話系統(tǒng)開始使用調(diào)頻模擬信號。最近幾混合差分-時分復(fù)用數(shù)字系統(tǒng)得到發(fā)展，表面上提高了服務(wù)質(zhì)量和能力。在所有這些系統(tǒng)，每個用戶指派特定時間頻率槽。但在大型系統(tǒng)的任務(wù)時頻時段不能獨(dú)一無二的特殊。讀卡器必須再用多信元為了覆蓋大的服務(wù)領(lǐng)域，在這些系統(tǒng)上令人滿意表現(xiàn)取決于控制系統(tǒng)間的相互干擾。重用的概念是常見的，甚至在電視廣播中，毗鄰城市的頻道也不是全新的。北美蜂窩撥出大約416名省級渠道經(jīng)營（30千赫間隔，總共分配12.5兆赫，在每個方向看到的頻率計(jì)劃）。理想化的幾何體系的數(shù)字顯示。同樣的頻率顯然不能再用任何一雙相鄰的信元，因?yàn)橛脩糁g的邊界這些干細(xì)胞可以同時接收信號，提供平等的振幅,從而導(dǎo)致了極高干擾。同一平面可以用六角細(xì)胞標(biāo)記，按照七程數(shù)字顯示模式。因此,如果是一個獨(dú)特的渠道，是分配給每個七個信元，然后可以重復(fù)布局不違反規(guī)定鄰接。雖然這只是是理想化模式并不真正嚴(yán)格適用于所有系統(tǒng)，但是七個程回格局大體正確?該系統(tǒng)建成這樣是決定于帶寬和seven-way使用模范。在一個省級系統(tǒng)，因此，每單元的最大容量大約416/7=59。三路扇區(qū)細(xì)胞，K=7再用同樣適用所有三個部門,也就是大約只有19個頻道,可在各個部門。在一個理想的幾何模式重用模式，使用不同的顏色代表頻道在這