简介：Heterogeneouscellularnetworksimprovethespectrumefficiencyandcoverageofwirelesscommunicationnetworksbydeployinglowpowerbasestation(BS)overlappingtheconventionalmacrocell.ButduetothedisparitybetweenthetransmitpowersofthemacroBSandthelowpowerBS,cellassociationstrategydevelopedfortheconventionalhomogeneousnetworksmayleadtoahighlyunbalancedtrafficloadingwithmostofthetrafficconcentratedonthemacroBS.Inthispaper,weproposeaload-balancecellassociationschemeforheterogeneouscellularnetworkaimingtomaximizethenetworkcapacity.Byrelaxingtheassociationconstraints,wecangettheupperboundofoptimalsolutionandconverttheprimalproblemintoaconvexoptimizationproblem.FurthermoreweproposeaLagrangemultipliersbaseddistributedalgorithmbyusingLagrangedualtheorytosolvetheconvexoptimization,whichconvergestoanoptimalsolutionwithatheoreticalperformanceguarantee.Withtheproposedalgorithm,mobileterminals(MTs)needtojointlyconsidertheirtraffictype,receivedsignal-to-interference-noise-ratios(SINRs)fromBSs,andtheloadofBSswhentheychooseserverBS.SimulationresultsshowthattheloadbalancebetweenmacroandpicoBSisachievedandnetworkcapacityisimprovedsignificantlybyourproposedcellassociationalgorithm.

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简介：1.IntroductionThearticlebyFinkandHouston1inthisspecialissueofJournalofSportandHealthScienceprovidesanexcellentexampleofimplementinganevidence-basedfallpreventionprograminrealcommunitieswithdiverseculturesofelderlypopulations.Althoughpreliminary,theprojectrevealedanumberofinterconnectedbarriersandfacilitatorsthatshedlightonpracticalimplications("lessonslearned")forpolicymakersandprogramprovidersregardingimplementationofanyevidence-basedintervention.WhileapplaudingFinkandHouston'seffort,inthiscommentaryweshareourexperienceswithTaiJiQuan:MovingforBetterBalance(TJQMBB)2inthestateofMaryland,withadiscussionofourownsetoflessonslearnedintermsofsuccessesandchallenges.

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