D-Link DWL-3600AP - Page 61

ModifyingRadioSettings
D-Link UnifiedAccessPointAdministrator’sGuide
November2011 Page61
UnifiedAccessPointAdministrator’sGuide
Channel SelecttheChannel.
Therangeofavailablechannelsisdeterminedbythemodeoftheradiointerfaceandthe
countrycodesetting.IfyouselectAutoforthechannelsetting,theAPscansavailable
channelsandselectsachannelwherenotrafficisdetected.
Thechanneldefinestheportionof
theradiospectrumtheradiousesfortransmittingand
receiving.Eachmodeoffersanumberofchannels,dependingonhowthespectrumis
licensedbynationalandtransnational authoritiessuchastheFederalCommunications
Commission(FCC)ortheInternationalTelecommunicationUnion(ITU‐R).
Whenautomaticchannelassignmentisenabledonthe
ChannelManagementpagefor
Clustering,thechannelpolicyfortheradioisautomaticallysettostaticmode,andthe
AutooptionisnotavailablefortheChannelfield.Thisallowstheautomaticchannel
featuretosetthechannelsfortheradiosinthecluster.
ChannelBandwidth
(802.11nmodes
only)
The802.11nspecification
allowsa40‐MHz‐widechannelinadditiontothelegacy20‐
MHzchannelavailablewith othermodes.The40‐MHzchannelenableshigherdatarates
butleavesfewerchannelsavailableforusebyother2.4GHzand5GHzdevices.
Setthefieldto20‐MHztorestrictthe
useofthechannelbandwidthtoa20‐MHz
channel.
PrimaryChannel
(802.11nmodes
only)
Thissettingcanbechangedonlywhenthechannelbandwidthissetto40MHz.A40‐
MHzchannelcanbeconsideredtoconsistoftwo20‐MHzchannelsthatarecontiguous
inthefrequencydomain.These
two20‐MHzchannelsareoftenreferredtoasthe
PrimaryandSecondarychannels. ThePrimaryChannelisusedfor802.11nclientsthat
supportonlya20‐MHzchannelbandwidthandforlegacyclients.
Selectoneofthefollowingoptions:
• Upper—SetthePrimaryChannelastheupper20‐MHz
channelinthe40‐MHzband.
•Lower—SetthePrimaryChannelasthelower20‐MHzchannelinthe40‐MHzband.
ShortGuard
IntervalSupported
Thisfieldisavailableonlyiftheselectedradiomodeincludes802.11n.
Theguardintervalisthedeadtime,innanoseconds,betweenOFDMsymbols.The
guard
intervalpreventsInter‐SymbolandInter‐CarrierInterference(ISI,ICI).The802.11nmode
allowsforareductioninthisguardintervalfromtheaandgdefinitionof800
nanosecondsto400nanoseconds.Reducingtheguardintervalcanyielda10%
improvementindatathroughput.
Selectoneofthefollowing
options:
•Yes—TheAPtransmitsdatausinga400nsguardIntervalwhencommunicatingwith
clientsthatalsosupporttheshortguardinterval.
•No—TheAPtransmitsdatausingan800nsguardinterval.
STBCMode Thisfieldisavailableonlyiftheselectedradiomodeincludes802.11n.
SpaceTime
BlockCoding(STBC)isan802.11ntechniqueintendedtoimprovethe
reliabilityofdatatransmissions.Thedatastreamistransmittedonmultipleantennasso
thereceivingsystemhasabetterchanceofdetectingatleastoneofthedatastreams.
Selectoneofthefollowingoptions:
•On—TheAPtransmits
thesamedatastreamonmultipleantennasatthesametime.
•Off—TheAPdoesnottransmitsthesamedataonmultipleantennas.
Table19:RadioSettings(Cont.)
Field Description