cellular radio

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CELLULAR RADIO

Identifyingthe cellularradiosystemDescribes the principlesand characteristics ofcellular radioDraw ablockof unit moblile communication'Explainthe functionsof eachblock ofthe mobile communicationsDifferentiatecontrolchannelsandvoicechannelsIdentifyingthe typesand characteristics of theantennaOBJECTIVE :INTRODUCTIONCellularRadioCommunicationsSystemisatwo-wayform of communication.usingradio wavescellularphonecan be connected tothetelephonesystem,where it isconnectedto the world.BellTelephone Company,theAT &Thascreate acellularradiosystemat the endof the 70sand fully implemented in early1980.Known as Advanced Mobile Phone Service(AMPS).CELLULAR RADIO PRINCIPLES Each cellconsists of areceiver andtransmitterwith low powercalled 'RadioBaseStation'(RBS) .enable it toprovide servicestothe userin the coverage ofseveralsquare kilometers.

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MTSO

There aretransmitter and receiverwhere itdividesits services to smaller areas called CELLThe smaller the radius of a cell, the higher the available bandwidth. So, in highly populated urban areas, there are cells with a radius of a few hundred metres, while huge cells of up to thirty kilometres provide coverage in rural areas. Each cellis connectedbytelephone linesormicrowaveto theMainControlCenter, known as Mobile Telephone Switching Office(MTSO).

CHARACTERISTICS OF CELLULARRADIO COMMUNICATION SYSTEM Whenuser moves out ofone celltoanother cell, theyautomaticswitchingsystem to the another RBS. Recipientsineach cellwill monitorthe signal strength ofthemobileunit.Whensignal strengthfallsto a level below theprescribedlevel, orreference, then itwill automatically beswitchedtoa higher levelthroughthe nearestRBS.BASIC COMPONENT OF RADIO CELLULAR COMMUNICATION SYSTEMUnit Mobile : Is a consumer devices that usedto makeandreceive calls.

Radio Base Station (RBS): Isan outside station-guard cells Controller that received instructionsfrom theMTSO.usingthe radio channel thatfound inevery cellincluding the voicechannelsandcontrolchannels Supervisethe callwhich includesmonitoringonspeechqualityand measurementonthe strength ofthe voicesignal. Send and receivevoicesignalsanddata from/to consumers.asan interface betweenusersand systems.

Mobile Telephone Switching Office (MTSO): Amobileswitchingcenter, as the heart ofthe systemPerform theswitchingoperation betweencellular networks and publictelephonenetwork.Receive and processdatareceived from theRBS includethe status ofmobileunits,diagnosticdata, informationfor billing,data textand so on. implementingsupervisorythat determineand updating thelocations ofmobileunitswhen there ismovement fromonecell tocell. Implementingthe flowto determinethe appropriatecells andthe necessaryradiochannelswhen a call isto be made. CELLULAR PHONE UNIT

TransmiterFrequency SynthesizerReceiver Logic UnitControl UnitCellular Phone cellular phone block diagramTRANSMITTER.Low-powerFMtransmitters,frequency range825MHzto 845MHz.Has atransmissionchannel666at a distance of30 kHz each other.Power emissions:Mobileradio=3WMobile phone=500mWFrequency synthesizer. To generate thesignalsfor the use oftransmitter and receiverUsing aPLLcircuit(PhaseLockedLoop),where the hablor oscillatorprovide the frequency needed.

receiver.

It is dual-conversion superhetrodin.Frequency Range= 870.03 MHz to 870.98 MHz.there are666channelreceiverat30kHzfrequencyrangeof each other.For eachchannel,the frequency oftransmissionand receivingdistinguishedat a distance of45 MHz.For example;atafrequencytransmissionchannelis825.03MHzwhile thefrequency ofacceptance forChannel 1is 870.03MHz, thenthedifferencebetween themis 45MHz. Logic unit.

Consist of main control circuit for cellular unitThis part is using a microprosessor (RAM &ROM.)Containsan additionalcircuitwhich is used tointerpret signals from theMTSOor cells,and to generatecontrol signalsfor thetransmitter and receiver. Control Unit .

Consist of speaker, microphone and keypad(touch-tone).Microprocessor used to control the LCD display and indicators in unit mobile.microprocessormemory is capable of storingthefrequently callednumbersand theautomaticdialingsystem.

3.3 RADIO channelControl ChannelVoice Channel Radio Channel

is atwowayradio transmissionpathbetween theRBS(RadioBaseStation)andmobile unitsEach channelusesdifferentfrequenciesfortransmissionfrom theRBSanothertransmission frommobileunittoRBSUsedifferent frequenciesto avoidinterference or overlappingsignal between transmitter and receiverFrequency@the samechannelcan be usedbyother cellsthatare far awayfrom each otherControl Channel

Each cell hasone (1)controlchannelthat is used only for transmission of data(notvoice)Controlchannelcontinuouslycontrol the flow ofdatawhen themobileunitis ONWhen the usermoves fromone cell toanother cell,the terminalswill be adjusted toanew controlchannelautomaticallywithin the operating system.Controlchannelwiththe bestreceptionqualitywill be selectedandset ofmobileterminalswill thenbe adjusted tothischanneluntil thequality ofreceptiondecreases.Voice Channel

Channelwhich broughtconversationsignalandusedduringconversation took placeEach cellusually hasbetween7to 23voicechannelsBesidesbringingthe conversationsignals, this channelalso route to:

*TonegeneratorSAT(SupervisoryAudioTone)*Data Message*Signalingtonedetection*Ringingorder deliveryAt Radio Base Station (RBS), there are TWO(2) types of antenna used:- Omnidirectional Directional

Antennais used as amedium of communicationbetween the receiver andtransmittersignal.Antenna

Antennahasa stability ofsending and receivingsignals.Usedinlesspopulatedareas/rural areasThecoverage arearound in shapeand everycoverage areacircleend would overlapbetween oneanotherUsingonlyone element.Omnidirectional Antenna

Coverage area for omnidirectional antenna

Antennathat have a directionalnature, wheretransmissionisin a certaindirection.Requiresthreeantennasarrangedso that eachantenna nearacorner of120coverageUsedinlarge areassuch asurban, townDirectional Antenna

Directional AntenaOmnidirectionalDirectionalCoverage area = Circle-shapedarea and overlapeach otherCoverage area = Balancedcoverageareaandare arranged ina hexagonalandnon-overlappingantennabeam= 360 each RBSantennabeam= 120 each RBS

RBS = located at the middle of cell.RBS = located at the edge of cellUsed = in rural areas/low population areaUsed = in urban/town areas or high population areaCOMPARISONQUIZ 2What is the basic component of radio cellular communcation system?Cellular radio principles is ____________________________________________________________________________________Differentiate directional and omnidirectional antenna.THANK YOU