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TELE9754CodingandInformationTheoryResearchWorkshopReportProjectIDProjectTopic-ABriefReviewOnMIMOTechnologyAuthorNameStudentIDE-mailLikaiMaz3326280malikai0409@yeah.netAbstract—Mobilewirelesscommunicationhasbecomeoneofthemostimportantaspectsofourdailylife.Thecontinuouslyincreasingusagehasimposedgreatpressureupontelecommunicationsystemwheretheavailabilityofchannelcapacityandspectralresourcesarelimited.MultipleInputMultipleOutput(MIMO)isconsideredasoneofthepossiblesolutionstotheaboveproblemandhasattractedconsiderableattentionamongresearchersandengineersinthefieldofmobilecommunicationduetothegreatadvantagesitexhibits.Inrecentyears,MIMOtechnologyhasbeendevelopedintomoresophisticatedformsandutilizedinsomecommoncommunicationdevicesaroundus.ThisreportisintendedtoprovidereaderswithabriefreviewofthehistoricalandtechnologicaldevelopmentsofMIMO,anditsapplications.I.INTRODUCTIONOurwirelesscommunicationsystemshaveundergoneremarkabledevelopmentsandprogressesinthepast20years,from1Gto4Gandtheupcoming5G.Suchsystemshaveprovidedourlifewithsignificantconvenienceswhichwereotherwiseimpossibleandunachievablebeforethe1980s.However,undertheconditionoflimitedbandwidthresourcesandchannelcapacity,thedevelopingcommunicationschemeisunabletomeetthefastgrowingdemandfromusersofmobiledevices.Inotherwords,ourcommunicationsystemhassomewhatattaineditsbottleneckandneedssomenewtechnologytoenhanceitsperformance.Ontheotherhand,MIMOequippedwithmodernefficientsignalprocessingtechniquesandprocessinghardwaredemonstratesprominentcharacteristicsthatcouldbetakentomitigatetheaboveproblems.MIMOcanbedefined,insimpleterms,asasystemwhichconsistsofmultipleantennasatboththetransmitterandreceiversides[6].AsystematicdiagramofMIMOisillustratedbyFigure1.Figure1.SystematicdiagramofaMIMOsystemTheunderlyingfactwhichenablesMIMOtoattractintenseattentionisthatitcouldexploittheadvantagesofbeamforminggain,spatialdiversityandspatialmultiplexingtoenhancetheperformanceofacommunicationsystemwithoutextraconsumptionofspectralresources.Thecontentofthisreportisorganizedinsixseparatesections.SectionIIoffersreadersasetofabbreviationsusedthroughoutthereport.SectionIIIillustratesthehistoricaldevelopmentsandmilestonesofMIMOfromtheorytoimplementations.SectionIVintroduces,ingeneralsense,howMIMOfunctionsandachievestheaforementionedadvantages.SectionVcategorizesMIMOintovariousclassesbasedonthepropertiesitcomposesandsomecomparisonsamongthemwouldbemade.SectionVIprovidessomeexamplesofapplicationofMIMOinmoderncommunicationscheme.Finally,abriefconclusionwillbedrawninSectionVI.AdditionalinformationcanbefoundbyreferringtotheAppendixsection.II.TABLEOFABBREVIATIONSThefollowingtable(Table1)listsasetofcommonlyABRIEFREVIEWONMIMOTECHNOLOGYANDITSAPPLICATIONSLikaiMaz3326280usedabbreviationstowhichwillbereferredinthefollowingsectionsofthisreport.Table1.TableofabbreviationsIII.HISTORICALDEVELOPMENTOFMIMO[1]ThehistoryofMIMOcanbedatedbackseveraldecadesago.AlthoughtheideaofMIMOwasnotproposeduntilthe1970s,antennaarrays,alsoknownassmartantennas(illustratedinFigure2)hadbeendevelopedtotaketheadvantageofdiversityandenhancewirelesstransmissionandreceptioninanaloguecommunications.CLASSIFICATIONOFMIMOFigure2.Anexampleofantennaarray.TheideaofMIMOwasfirstconceivedinthe1970sinBellLaboratory,whichwasinspiredbythedesiretoovercometheproblemofbandwidthlimitationandinterferenceintransmissioncables.Suchideawastoodifficulttoberealizedandhadremainedintheformoftheoryforalongperiodoftime,duetothelimitationthattheprocessinghardwareandsignalprocessingalgorithmsavailableatthatstagewasunabletosupportMIMOsignalprocessing.Nevertheless,thetheoryofMIMOhadcontinuedtobeenrichedbysomeoftheearlyresearchers’,includingA.RKaye,D.AGeorge,Branderburg,WynerandW.Van.Etten.Inthelate1980s,MIMOtheoryhadfurtherbeendevelopedbyJackSalzandJackWinterswhoseworkcentralizedaroundtheideaofbeamforming.TheconceptofSMwasproposedin1993byArogyaswamiPaulrajandThomas.In1996,GregRaleighandGerardJ.FoschinifurtherdevelopedtheapproachestowardsMIMOusingco-locatedantennasatthetransmitter.SignificantbreakthroughinpracticalapplicationofMIMOdidnottakeplaceuntilthelate1990s.In1998,SMwasfirstdemonstratedintheformFigure2.TimelineofdevelopmentofMIMO.ofprototypeinBellLab.Sincethen,thedevelopmentofMIMOhadbeenacceleratedandsomeproductswithsuchtechnologyintegratedstartedtobeavailablecommercially.In2002,IospanWirelessInc.launchthefirstcommercialproductwithMIMOembedded,whichwasamilestoneintherealapplicationofthistechnology.Later,in2005,thefirststandardofWLAN(IEEE802.11n),alsocommonlyknownasWi-Fi,withMIMO-OFDMwasproducedbyAirgoNetworksandhasbecomemoreandmorepopularsincethen.ThemoredetailedhistoricaldevelopmentofMIMOisdepictedasatimelineandcanbefoundinFigure2.IV.HOWDOESMIMOWORKTheunderlyingprincipleofMIMOisthatsignalstransmittedandreceivedatboththetransmitterandreceiversidescombinetogethersothateitherparalleldatasub-streamsareformedorSNRisimproved[3].ThebenefitsthatMIMOexploitsareknownasbeamforming,spatialdiversityandspatialmultiplexing.Figure3.SmithchartshowingthetechniqueofbeamformingBea