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UniversityofTwenteFacultyofElectricalEngineeringChairSignalsandSystemsDevelopmentofatest-bedforsmartantennas,usingdigitalbeamformingByTacoKluwerM.Sc.ThesisReportno:S&S-015.01December2000-August2001Supervisors:Prof.Dr.Ir.C.H.SlumpIr.R.SchiphorstIr.F.W.HoeksemaSUMMARYThisreportdescribesthedevelopmentofasmartantennatest-bed.Thetest-bedisconfiguredasareceiverandcanprocessthesignalsofamaximumoffourantennas.Thereceiverstructureisbasedontheheterodynereceiverconcept.Theheterodynereceiverischaracterizedbytwostages.Thefirststageconvertsthereceivedsignaltoanintermediatefrequency,andthesecondstageconvertsthissignaltothebaseband.Asetupisconfiguredtosimulatethefirststagebyusingprogrammablefunctiongenerators.Thesecondstageofthefront-endisperformeddigitally.Forthisaquadanalog-to-digitalconverterisusedincombinationwithadigitalsignalprocessor.Theanalog-to-digitalconverterandthedigitalsignalprocessorareeditionsofTexasInstrumentsforevaluationpurposes.Thedigitaldownconversionandthebeamformingtasksaredefinedbysoftware.Twoalgorithmsareconsideredtobeimplemented;theLeastMeanSquarealgorithmandtheConstantModulusalgorithm.TheConstantModulusAlgorithmissimplertoimplementasitisablindalgorithmanditdoesnotrequiresynchronization.Thesoftwareplatformisformedbyareal-timeoperatingsystem,whichiscalledDSP/BIOS.Thesoftwareobjectsthataredesigned,functionasreal-timetasks.Thetest-bedisdesignedforcontinuousoperation.Adriverfortheanalog-to-digitalconverterisimplemented.Thedigitaldownconverterisimplementedandtestedfortwochannels.Extensiontofourchannelscanbedoneeasily.Thesoftware-defineddigitalbeamformerisimplementedfor2channels.ThesystemhasbeentestedforMSKsignalsfortheinterferingsignalasthedesiredsignal.Thesystemdemonstratedsuccessfulsuppressionoftheinterferingsignal.PrefaceWirelesstelecomhasalwaysbeenoneofmymajorinterests.Nowadaysthetelecomsectorisgrowingfastanditsbehaviorisdynamic,hazardousandturbulent.Atthestartofa3rdgenerationnetworkformobilecommunications,newtechnologies,demandsandrestrictionsarise.TechnologiesasGSM,DECT,IS95willevolvetonewstandardssuchasUMTS.BesidesthesetechnologiesBluetooth,wirelessLANandHomeRFcameup,showingmanycompletelynewinsightsandapplications.Thisenormousamountoftechnologyanditspotential,askforcreativeandsmartsolutions.Oneofthedevelopmentsinwirelesstelecomthatinterestsmeisthesmartantenna.Smartantennatechnologycanhavegreateffectonmanyimportantparametersinthewirelesscommunication.Benefitstobegainedareamongothersintheareaofbandwidth,bitrates,interferencerejection,powereconomy,andreliability.Highpotentialindeed,andthereforesmartantennatechnologyisatthismomentahottopicforthewirelessindustry.Thebasicideabehindsmartantennasisthatmultipleantennasprocessedsimultaneouslyallowstaticordynamicalspatialprocessingwithfixedantennatopology.Thepatternoftheantennainitstotalityisnowdependingpartlyonitsgeometrybutevenmoreontheprocessingofthesignalsoftheantennasindividually.Smartantennasenablebeamformingtoaimattargetsorpatternmodificationtoformthebestsolutionforsignaltonoiseperformanceorenergyeconomy.FormyMaster’sthesisIchosesmartantennasasanareatofocuson.IapproachedthechairSignalsandSystemsformythesisasitsresearchinterestsshareacommonfieldwithmyinterests.Duringmythesisanassignmentwasformedandcarriedout.Thefinalresultofthethesisisthisdocumentcontainingmyexperiencesandachievements.Iwouldliketothankmysupervisors,KeesSlump,RoelSchiphorstandFokkeHoeksema,fortheirsupportandadviceduringtheThesis.FurthermoreIwouldliketothankHennyKuipersandGeert-JanLaanstrafortheirsupportonthepracticalwork.TacoKluwerTableofContents1Introduction.................................................................................................................11.1Definingtheassignment..............................................................................................21.2Overview.....................................................................................................................22Smartantennasfundamentals.....................................................................................52.1Differentapproaches...................................................................................................52.2Smartantennabasics..................................................................................................72.3Adaptivebeamforming...............................................................................................92.4TheLMSalgorithm..................................................................................................102.5ConstantModulusAlgorithm...................................................................................133Radiofrequencyfront-end.........................................................................................153.1RadioFrequencyTransceiver..................................................................................153.2ReceiverFundamentals.............................................................................................173.3Receiverbuildingblocks.....................