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... replaced by a switch-beam antenna system. The SBS
operates by sniffer scanning the beamformer outputs to detect the best two beams which are then
c
1999 by CRC Press LLC
Note that S(k) by definition ... higher
order statistics,
IEEE Trans. on Acoustics, Speech, and Signal Processing,
37(3), 360–377,
March 1989.
c
1999 by CRC Press LLC
ArrayProcessingforMobile
Communications
A.Paulraj
StanfordUniversity
C.B.Papadias
StanfordUniversity
68.1IntroductionandMotivation
68.2VectorChannelModel
PropagationLossandFading
ã
MultipathEffects
ã
Typical
Channels
ã
SignalModel
ã
Co-ChannelInterference
ã
Signal-
Plus-InterferenceModel
ã
BlockSignalModel
ã
Spatialand
TemporalStructure
68.3AlgorithmsforSTP
Single-UserST-MLandST-MMSE
ã
Multi-UserAlgorithms
ã
SimulationExample
68.4ApplicationsofSpatialProcessing
SwitchedBeamSystems
ã
Space-TimeFiltering
ã
Channel
ReuseWithinCell
68.5Summary
68.6References
68.1 ... IntroductionandMotivation
Thischapterreviewstheapplicationsofantennaarraysignalprocessingtomobilenetworks.Cellular
networksarerapidlygrowingaroundtheworldandanumberofemergingtechnologiesareseentobe
criticaltotheirimprovedeconomicsandperformance.Amongtheseistheuseofmultipleantennas
andspatialsignalprocessingatthebasestation.ThistechnologyisreferredtoasSmartAntennasor,
moreaccurately,asSpace-TimeProcessing(STP).STPreferstoprocessingtheantennaoutputsin
bothspaceandtimetomaximizesignalquality.
Acellulararchitectureisusedinanumberofmobile/portablecommunicationsapplications.Cell
sizesmayrangefromlargemacrocells,whichservehighspeedmobiles,tosmallermicrocellsorvery
smallpicocells,whicharedesignedforoutdoorandindoorapplications.Eachoftheseoffersdifferent
channelcharacteristicsand,therefore,posesdifferentchallengesforSTP.Likewise,differentservice
deliverygoalssuchasgradeofserviceandtypeofservice:voice,data,orvideo,alsoneedspecic
STPsolutions.STPprovidesthreeprocessingleverages.Therstisarraygain.Multipleantennas
capturemoresignalenergy,whichcanbecombinedtoimprovethesignal-to-noiseratio(SNR).Next
isspatialdiversitytocombatspace-selectivefading.Finally,STPcanreduceco-channel,adjacent
channel,andinter-symbolinterference.
Theorganizationofthischapterisasfollows.InSection68.2,wedescribethevectorchannelmodel
forabasestationantennaarray.InSection68.3wediscussthealgorithmsforSTP.Section68.4outlines
theapplicationsofSTPincellularnetworks.Finally,weconcludewithasummaryinSection68.5.
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1999byCRCPressLLC
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