Radwin 2000 - GSU Redundancy; Figure 14-3 Phase Shifted

RADWIN2000UserManual Release2.8.30 14‐3
CascadedSitesusingShiftedPhaseTransmission
CascadedSitesusingShiftedPhaseTransmission
Thesolutionofferedhereisnota“universalcure”.Thefollowingconditionsarenecessary,
butinanyspecificcasemaynotbesufficient:
• TheGSUsites(marked1,and3above)aresufficientlyfarapartastoensurethatthereis
nomutualinterferencebetweencommunicatingsites(1‐2and2‐3above)
• Thereshouldbenointerferencebetweennon‐communicatingsites(1and3above).
Toseehowitworks,weuseFigure14‐2.TheGSUtowersarenumberedandmarkedfor
cascading,1‐2and2‐3.Thereshouldnotbealinkbetween1and3.
TheGSUcansynchronizetheTDDtimingofseveralsitesenablingthecascadingof
consecutivelinkswithoutmutualinterference.
Tousecascading,theTDDtimingoftheeven‐orderedlinks(GSU2above)mustbe“shifted”
(ShiftedPhase)andodd‐orderedlinks(GSU1andGSU3above)mustbe“unshifted”(Normal
Phase).ThephaseshiftishalfoftheRadioFrameDuration(RFD)fromthechosenRFP.The
schemeisshowninFigure14‐3.
SincetheGSUisalwa ysHSSmaster(HSM),ateachGSUlocation,theGSUcan“force”the
synchronizationofitscollocatedradios.ByhalfRFDshifting,alt ernatecollocatedsitescantalk
toeachother.
Figure14‐3:Phaseshiftedtransmission‐phaseshiftis1/2theRFD
ChoiceofnormalorshiftedphaseisconfigurableperGSUusingtheRADWINManager.
GSURedundancy
TheGSUisdesignedtosupportredundancy,improvingtherobustnessofaGSUbased
topology.
Inredundancymode,twoGSUsareinstalledatthesameHSSsite.Oneofthemself‐
configurestogenerateHSSsyncsignals.WewillcallitthePrimaryunit.Theotherone,the
SecondaryunitremainsdormantmerelypollingthefirstGSU.IfthePrimaryGSUfails,then
theSecondaryGSUbecomesactiveimmediately.IfthePrimaryunitbecomesactiveagain,it
remainsdormant,reversingtheoriginalroles.ThechoiceofthePrimaryGSUisrandomand
ofnosignificance.