User's Manual

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41
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Chapter4 | WirelessSettings 
RadioSettings 
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◆ WMM—SetstheWMMoperationalmodeontheaccesspoint.Whenenabled, 
theparametersforeachAccessCategory(AC)queuewillbeemployedonthe 
accesspoin tandQoScapabilitiesadvertisedtoWMM‐enabledclients.  (Default:
Enabled)
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Whenenabled,WMMmustbesupportedonanydevicetryingtoassociated  with
theaccesspoint.Devicesthatdonotsupportthisfeaturewillnotbe
 allowedto
associatewiththeaccesspoint.
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Wirelessnetworksofferanequalopportunityforalldevicestotransmitdata 
fromanytypeofapplication.Althoughthisisacceptableformostapplications, 
multimediaapplications(withaudioandvideodata)areparticularlysensitive
tothedelayandt hroughputvariationsthatresultfromthis“equalopportunity”
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wirelessaccessmethod.Formultimediaapplicationstorun welloverawireless 
network,aQualityofService(QoS)mechanismisrequiredtoprioritizetraffic
typesandprovidean“enhance dopportunity”wirelessaccessmethod.
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TheaccesspointimplementsQoSusingtheWi‐FiMultimedia(WMM)standard. 
UsingWMM,theaccesspointisabletoprioritizetraff ic andoptimize 
performancewhenmultipleapplicationscompeteforwirelessnetwork
bandwidthatthesametime.WMMemploystechniquesthatareasubsetofthe
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IEEE802.11eQoSstandardanditenablestheaccesspointtointer‐operatewith 
bothWMM‐enabledclientsandotherdevicesthatmaylackanyWMM 
functionality.
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AccessCategories—WMMdefinesfouraccesscategories(ACs):voice,video, 
besteffort,andbackground.Thesecategoriescorrespondtotrafficpriority 
levelsandaremappedtoIEEE802.1Dprioritytags(seeFigure2,“WMMAccess 
Categories",onpage41).ThedirectmappingofthefourACsto802.1D
prioritiesisspecificallyintendedtofacilitateinteroperabilitywithotherwired
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networkQoSpolicies.WhilethefourACsarespecifiedforspe cifictypesof
traffic,WMMallowstheprioritylevelstobeconfiguredtomatchanynetwork‐
wideQoSpolicy.WMMalsospecifiesaprotocolthataccesspointscanuseto
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communicatetheconfiguredtrafficprioritylevelstoQoS‐enabledwireless 
clients.
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Table2:WMMAccessCategories 
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AC_VO (AC3) Voice Highest priority, minimum delay.Time‐sensitive
datasuchasVoIP(VoiceoverIP)calls.
AC_VI(AC2) Video Highpriority,minimumdelay.Time‐sen sitive data
suchasstreamingvideo.
7,6
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5,4
AC_BE (AC0) BestEffort Normal priority, medium delay andthroughput.
Dataonlyaffectedbylongdelay s.Datafrom
applicationsordevicesthatlackQoScapabilities.
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AC_BK(AC1) Background Lowestpriority.Datawithnodelayorthroughput 
requirements,suchasbulkdatatransfers.
0,3
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2,1
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Access 
Category 
WMM Description
Designation
802.1D
Tags