AirLink Communications Raven X HSDPA Uživatelská příručka Strana 14

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Introduction to the Raven XE
Rev 2.0 Jul.09 7
fromNodeB(knownasHARQHybridAutomaticRepeat
Request)todelivertheimproveddownlinkperformancevs.
UMTSandEDGE.
HSPDA(andHSUPA)fallsbacktoUMTS,EDGEorGPRS (in
orderofprecedence).Thisfeatureallowsyoutohaveseamless
connectivitynomatterwhereyourRavenXEis.
UMTS
UMTS(UniversalMobileTelecommunicationsSystem)
supportsupto1920kbit/sdatatransferrates,althoughmost
userscanexpectperformanceupto384kbit/s.AUMTS
networkusesapairof5MHzchannels,oneinthe1900MHz
rangeforuplinkandoneinthe2100MHzrangefordownlink.
EDGE
EDGE(EnhancedDataratesforGSMEvolution)providesend
toendpacketdataserviceswithanenhancedconnectivity
buildingonGPRStechnologyandusingtheestablishedGSM
networks.EDGEprovideshighertransmissionratesandbetter
transmissionqualityfordatathanGPRS.EDGEcancarrydata
atspeedstypicallyupto 384
kbit/sinpacketmode.
WhenEDGEisnotavailable,yourRavenXEwillfallbackto
GPRSfortheconnectiontoyourcellularprovidedtoprovide
continuedconnectivity.
GPRS
GeneralPacketRadioService(GPRS)ispacketswitchedwith
manyuserssharingthesametransmissionchannel,butonly
transmittingwhentheyhavedatatosend.Thismeansthatthe
totalavailablebandwidthcanbeimmediatelydedicatedto
thoseuserswhoareactuallysendingatanygivenmoment,
providinghigherutilizationwhere
usersonlysendorreceive
dataintermittently.GPRSprovidesspeedsof30–70kbpswith
burstsupto170 kbps.
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