简介:Thispaperanalyzesaqueuemode]ofthepollingsystemwithlimitedservice(K=1)indiscretetime.BytheimbeddedMarkovchaintheoryandtheprobabilitygeneratingfunctionmethod,themeanvaluesofqueuelengthandmessagewaitingtimeareexplicitlyobtained.Also,wegivethesimulationresults.TheresultsobtainedbyH.Tagai(1985)arerevised.
简介:Bydeducingthedistributionofthenormalizedchannelcovariancematrix,anovellimitedfeedbackschemeisproposedundermultipleusers(MU)multiple-inputmultiple-output(MIMO)broadcastchannel(BC)system.Theproposedschemehasadvantagesinthreeaspects.First,ithasnoconstraintsonthenumberofusersorantennas.Second,eachuser'sfeedbackbitsareindependentofthenumberofreceivingantennas.Third,theproposedschemeavoidsthestorageoflarge-sizecodebookonthetransceivers.Simulationresultsshowthattheperformanceoftheproposedschemeisclosetotheperfectchannelstateinformation(CSI)caseanditjustneedsasmallnumberoffeedbackbits.
简介:Multi-cellmulti-usermultiple-inputmultiple-output(MC-MU-MIMO)isapromisingtechniquetoeliminateinter-userinterferenceandinter-cellcochannelinterferenceinwirelesstelecommunicationsystems.AsthelargenumberofusersinthesystemandthelimitednumberofsimultaneouslysupportableuserswithMC-MU-MIMO,itisnecessarytoselectasubsetofuserstomaximizethetotalthroughput.However,thefullycentralizeduserselectionalgorithmsusedinsinglecellsystem,whichwillincurhighcomplexityandbackhaulloadinmulti-cellcooperativeprocessing(MCP)systems,arenotsuitabletoMC-MU-MIMOsystems.ThisarticlepresentsatwocascadeduserselectionmethodforMCPsystemswithmulti-cellblockdiagonalization.Inthispaper,alocaloptimalsubsetofusers,whichcanmaximizethelocalsumcapacity,isfirstchosenbythegreedymethodineverycooperativebasestationinparallel.Then,allthecooperativebasestationsreporttheirlocaloptimaluserstothecentralunit(CU).Finally,theglobaloptimalusers,whichcanmaximizetheglobalsumcapacityofMCPsystems,areselectedfromtheaggregatedlocaloptimalusersattheCU.Thesimulationresultsshowthattheproposedmethodperformscloselytotheoptimalandcentralizedalgorithm.Meanwhile,thecomplexityandbackhaulloadarereduceddramatically.