中继网络中的负载均衡研究

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1、中国科学技术大学硕士学位论文中继网络中的负载均衡研究姓名：余林洪申请学位级别：硕士专业：通信与信息系统指导教师：周武肠2011-05AbstractABSTRACTTherelaynetworkeffectivelymitigatestheproblemthattraditionalcellularnetworkscannolongermeetthepeople'srequirementofhigherdatatransmissionrate.Relaynodesinthenetworksdividealongertransmissionpa

2、thintosomeshorterpathswithbettertransmissionqualityanditcanincreasethesystemcapacity.Placingarelaynodeinthelocationwhereabasestationcan'tbesetconvenientlycanextendthecoverageareaofthesystem.Althoughrelaynetworkshavehighersystemcapacityandlargercoveragearea,duetotheuncertain

3、tyofpeople'smovement,therearestillsomehotcellsbeingoverloadedandmanynewcallsareblocked.Butinthesurroundingcells,theremaybemuchunusedresourcebecauseoflackingusers.Theproblemofloadimbalanceisstillseriousinrelaynetworks.Howtoutilizeloadbalancingstrategiestosolvethisproblemhasb

4、eenahotpointofresearch・Wealsoresearchtheloadbalancingstrategyinrelaynetworks.Wefirstlystudyloadbalancinginrelaynetworkswithmultipletraffictypesinthispaper・Wegiveamodelofloadbalancing,andformulateitasanoptimizationproblemwiththegoalofmaximizingthepercentageofsuccessfullyacce

5、ssedusers.Wegiveafive-steploadbalancingstrategytosolveit.Becausethedatarateofnon-real-timetrafficisvariable,wealsodynamicallycontroltherelationshipsofusers,relaysandbasestationstotransfertrafficfromhotcellstocooleronesanddecreasetheallocatedsub-channelsofuserswithnon-real-t

6、imetraffictoallowmoreuserstoaccessthenetwork.Itreducestheblockingprobabilityofusers.Inordertoensuretheperformanceofreal-timeusers,wegiveprioritytothem..Wealsostudyloadbalancingthatconsiderstheperformanceofusersmovingfromcelltocell.Indealingwithusers9callrequests,wefullycons

7、iderthedifferenceofnewcallsandhandovercalls,andgivealoadbalancingstrategythathandovercallshavehigherpriority.Inthisstrategy,wesetdifferentaccessthresholdfornewcallsandhandovercalls,andthenewcallshavehigherthreshold.Itmeansthatwesetsomeguardchannelsforhandovercalls,anditensu

8、reshandovercallshavemoreavailablechannels.Atthesametime,thedirectandindirectloadba