User's Manual

APPENDIXC
RADIOCONFIGURATION
Revised: 27 Jan 2017 APX C-4 ESTeem Horizon Series
DataRatesandThroughput
TheHorizonseriesradiosaredesignedtodynamicallychangetheir dataratebasedupontheircurrentreceivesignalstrength
andbackgroundnoisetoachievethehig hestthroughput.Itishighl y recommendedtoallowtheHorizontodynamicallyscaleto
thebestdata rategiventheope ra tio nconditions.Thefollowingtablesshowthedatarat
estheHorizonradioswi ll useandthe
receivesignalstrengthrequiredforeachlevel.
Glossary
LegacyIndexThisindexshowsthe dataratestheHorizonradioswillusewhenoperatingatlegacy802.11(802.11g,802.11bor
802.11a)ratesandto communicatewiththeolderESTe emModel195Eseriesradiomodems.
HTMCSIndexHighThroughput(HT)ModulationandCodingScheme(MCS)indexvaluelistgiveseverycombinationof
"numberofspatialstreams+modulationtype+codingrate"thatis possible.InpracticetheachievableMCSvaluewilldepend
onalargenumberofvariablessuchasreceivesignalstrength,availablebandwidth,RFbackgroundnoiseandotherusersona
givenchannel.TheMCSvaluewillonlytellthe 'overtheai
r'datarateofalinkandnotdefinewhattheactualusablethroughput
(seebelow).
DSSSDirectSequenceSpreadSpectrum.Thisisalegacymodulationtypeusedin802.11bwirelessnetworks.
OFDMOrthogonalFrequencyDivisionMultiplexingisthelatestmodulationschemeusedasadigitalmulticarrier modulation
method.Alargenumberofcloselyspacedorthogonalsubcarrier signalsareusedtocarrydataonseveralparalleldatastreams
orchannelstoachievethehigherthroughputsofthe802.11nprotocols.
Modul.(Modulation)‐Themodulationishowthedataistransportedonthecarrierfrequency.Therearemultipletypesof
modulationusedintheHorizonhardwareandtheyareli stedonthefollowingchartsstrictlyforreference.
CodingRate‐Thisisanindicationofhowmuchofthe datastreamisactuallybeingusedtotransmitus a b le data.Thisis
expressedasafractionwiththemostefficientratebeing5/6 or83.3%ofthe datastreambeingused.
GuardIntervalTheGuardInterval(GI )iseffectivelyaveryshortpausebetweenpackettrans missi ontoallowforanyfalse
informationtobeignored.ThelongerGuardIntervalcanimprovereliabilityinmoresaturatedwirelessnetwork s . Theinterval
shownisinnanoseconds(ns)oronebillionthofasecond(x109).
Bandwidth‐Alsoknownaschannelwidth,thisishowmuchofthefrequencyspectrumisbeingusedtotransportdata.The
maximumbandwidthusedbytheHorizonseriesis40MHz.Thetableshowsvaluesforavailablebandwidthbymodelwhich
directlycorrelatetotheradiothroughput.Forexample,a10MHzchannelwillprovidehalftheDataRateofa20MHz.
SignalThisistheamountofreceivesignalstrengthrequiredtoachie
veagivendatarate.Manyfactorssuchasradio
backgroundnoiseandotherusersinafrequencychannelwillgreatlyaffecttheamountofsignalstrengthrequired.Thevalues
providedaretobeusedasareferenceforlineofsight(LOS)pathlosscalculations.
RFRateThisistherateatwhichoneradiotransmitsdatafromonetoan
other.
ThroughputThedisplayedthroughputisanapproximationoftheeffectivedatarateofaradiosystemcomparedtosending
Ethernetdataoverstandardwire.ThisnumbertakesintoaccountfactorslikeRFpacketoverhead,retries,andlatencyofthe
radio.
dBmDecibelsinreferencetoamilliwatt(mW).Thisisastandardunitofreceivesignalstrength.
MbpsMega(million)bitspersecond.Thestandardunitofdatarateusedinhighspeedwirelessdevices.