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8/10/2019 4_SynCan2013 Sync Distribution Architectures for LTE
1/18
ConfidentialCopyright2012
JimOlsenApril2013
SynchronizationDistributionArchitecturesforLTENetworks
2ConfidentialCopyright2013
Agenda
Introduction:TheBasicProblem
Synchronization,StandardsandRequirements
SynchronizationDistributionArchitecturesforLTE
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TheBasicProblem
HowshouldIsynchronizemyLTEnetworks?
Theanswerisdrivenbyservicedeliverynetworkfundamentals:
SelectionofLTEtechnology(LTEFDD,LTETDD,LTEAdvanced)
drivesthesynchronizationrequirements
Mobilenetworkequipmentselectionandcellsitelocations
(particularlyforsmallcells)definewhatcanandcannotbedone
Backhaulnetworktechnologies,topologyandperformancedrivedecisionsforsyncequipmentselectionanddeploymentlocations
4ConfidentialCopyright2013
TheLTESynchronizationSolution
Onesolutiondoesnotfiteveryscenario.
SelectionofLTEtechnology(LTEFDD,LTETDD,LTEAdvanced)
drivesdifferentsynchronizationrequirements
Cellsitelocationsandmobilenetworkequipmentselectiondefine
whatcanandcannotbedone(particularlyforsmallcells)
Backhaulnetworktechnologies,topologyandperformancedrive
decisionsforsyncequipmentselectionanddeploymentlocations
NewEdgeMasterClocks,deployednearthenetworkedge,
enableavarietyofsynchronizationdistributionarchitectures
foravarietyofnetworkscenarios
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Synchronization,StandardsandRequirements
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TA=1/fA
TB=1/fB
fA=fB
Frequency Synchronization
A
B t
t
Frequency,PhaseandTimeSynchronization
Leadingedgeofthe
pulsesareatsame
pace,butnotatthe
identicalmoment.
Leadingedgeof
thepulsesareat
identicalmoment.
Leadingedgeof
thepulsesareat
theidentical
momentand
identicaltime.
TA=1/fA
TB=1/fB
Phase Synchroni zation
A
B t
t
fA=fB
TA=1/fA
TB=1/fB
fA=fB
Time Synchronization
A
B
t
t
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WhyisSynchronizationRequired?
ApplicationApplication Why YouNeedto
Comply
Why YouNeedto
Comply
Impactof
Noncompliance
Impactof
Noncompliance
CallInitiation
Timeslotalignment
Proper time alignment
of videosignaldecoding
frommultipleBTSs
Coordinationof signals
to/frommultiple
basestations
Interferencecoordination
CallInterference
Droppedcalls
Packet loss/collisions
Spectralefficiency
Video broadcast
interruption
Poorsignalquality
atedgeofcells,LBS
accuracy
Spectralinefficiency&
Servicedegradation
LTE FDD
LTETDD
LTEAMBSFN
LTEAMIMO/COMP
LTEAeICIC
Needsand
Impactsare
cumulative:
plusallofthe
above
Investmentinsmallcellsand LTEnetworksismadetoincrease
capacityandcoverage.Whensynchronizationfails,both
objectivesarelost.Andtheimpactisfeltbyyourcustomers!
Investmentinsmallcellsand LTEnetworksismadetoincrease
capacityandcoverage.Whensynchronizationfails,both
objectivesarelost.Andtheimpactisfeltbyyourcustomers!
8ConfidentialCopyright2013
FrequencyG.8261: Timing and Synchronization Aspects in Packet
Networks (Frequency)
Time/PhaseG.8271: Time and Phase Synchronization Aspects in
Packet Networks
G.8273: Packet-Based Equipment Clocks for
Time/Phase: Framework
StructureofITUTRecommendations
G.8265.1: Precision Time Protocol Telecom
Profile for Frequency Synchronization
G.8275.1: PTP Profile for Time and Phase
Synchronization (full timing support)
Basic Aspects
Clocks
Methods
Profiles
G.8265.2 PTP Telecom Profile for Frequency #2
G.8261.1: PDV Network Limits Applicable to Packet-
Based Methods (Frequency) G.8271.1: Network Requirements for Time/PhaseNetwork
Requirements
G.8273.1: Telecom Grandmaster (T-GM)
G.8262: Timing Characteristics of a Synchronous
Ethernet Equipment Slave Clock (EEC)
G.8263: Timing Characteristics of Packet-Based
Equipment Clocks (PEC)
G.8264: Distribution of Timing Information through
Packet Networks
G.8271.2: Reserved for future use
Definitions /
Terminology
G.8260: Definitions and Terminology for
Synchronization in Packet Networks
G.8261.2: Reserved for future use
G.8272: PRTC (Primary Reference Time Clock)
Performance
G.8273.2: Telecom Boundary Clock (T-BC)
G.8273.3: Telecom Transparent Clock (T-TC)
G.8273.4: Telecom Time Slave Clock (T-TSC)
G.8274: Reserved for future use
agreed ongoing options
G.8275:Architecture and Requirements for
Packet-Based Time and Phase Delivery
G.8265:Architecture and Requirements for Packet-
Based Frequency Delivery
G.8275.2: PTP Profile for Time and Phase
Synchronization (partial timing support) New!
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LTESynchronizationRequirements
ApplicationFrequency
Network / AirPhase Note
LTE FDD 16ppb / 50ppb NA sameas2Gand 3G
LTE TDD 16ppb / 50ppb 1.5s 3kmcellradius
5s >3kmcellradius
LTEMBMS(LTEFDD<ETDD)
16ppb / 50ppb 10s intercelltimedifference
LTEAdvanced 16ppb / 50ppb 1.5sto 5s Indiscussionbymembers
ofthe3GPP
New 1.5sto 5sphasetimingrequirementsrequirenewsynchronizationdistributionarchitectures
New 1.5sto 5sphasetimingrequirementsrequirenewsynchronizationdistributionarchitectures
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SynchronizationDistributionArchitectures
forLTENetworks
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3Guidelines
2.Protectyoursyncforserviceassurance
GNSS,PTP&Stablefrequencysource
Highperformanceholdover
3.DeployPTPGrandmasterwherethenetworkneedsitforaccuracy
Backhaulsupportsaccuracy:allowsdeploymentclosertothecore
Noisy,highPDVnetwork:requiresdeploymentatorneartheedge
1.Useanindependentsourceforsync
Bestinclasssolutions
Efficientoperationinamultivendornetwork
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4BasicNetworkScenarios
3.LTEphase,retrofittedornewEthernetbackhaul
SyncEandBoundaryClocksineverynetworkelement
2.LTEfrequency,highPDV,noisybackhaul
Diversetransporttechnologies,3rd Parties,manyhops
4.LTEphase,existingbackhaul,possiblyhighPDV,noisy
NoBC,possiblynoSyncE,diversetransport,3rd party
1.LTEfrequency,managedEthernetbackhaul
Consistent,lowPDV,knownbackhaulperformance
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1.FrequencySynchronization:
G.8265.1BasicArchitecture
ManagedEthernetbackhaulconsistent,knownperformance,lowpacketdelayvariation
CentraldeploymentofhighcapacityPTPgrandmaster
Commondeploymentmodeltoday:100sofnetworksworldwide
PDVmitigatedbyQoSforPTPflowandlimitingnumberofhops
CORE ACCESSAGGREGATION
MacroeNodeB
SmallCellAggregation
MetroSmallCells
PTPGM
PTPGM
Rb
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1.FrequencySynchronization:
G.8265.1
Basic
Architecture
SynchronizationDistributionArchitecture
Syncequipmentanddeployment
Macroagg.site:highcapacityPTPgrandmaster,
redundantequip.configurationandnetwork
protected
MacroeNodeB:highqualityPTPclient&high
qualityrubidiumoscillatorforholdover
Metrosmallcell:highqualityPTPclient(softGPS)
PTPdelivery:engineeredQoS/CoS orEVC/VPN,shortestpath
PTPprofile:G.8265.1,layer3,unicast
1or2stepclock
Pros
Fullyprotectedsynchronization
Proveninnetworksworldwide
Fullystandardsbased
ManagedEthernetbackhaul
consistent,knownperformance,lowpacketdelayvariation
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2.FrequencySynchronization:
G.8265.1EdgeArchitecture
Uncertainperformance,noisybackhaulMultipletechnologies,manyhops/paths,highpacketdelay
variation,3rd partyaccessvendors,etc.
SetfrequencywithPTPorGNSS
HoldfrequencywithPTPorGNSS
CORE ACCESSAGGREGATION
MacroeNodeB
SmallCellAgg.
MetroSmallCells
PTPGM
PTPGM
PON
ONU
Microwave
DSLmodemDSLAM
HighPDV/3rd Party
EdgeGM
EdgeGM
G.8265.1profile
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2.FrequencySynchronization:
G.8265.1
Edge
Architecture
SynchronizationDistributionArchitecture
Syncequipmentanddeployment
Macroagg.site:highcapacityPTPgrandmaster,
redundantequip.configurationandnetwork
protected
MacroeNodeBandsmallcellaggregationsites:
edgePTPgrandmasterwithGPS
MetroSmallCell:PTPclient(withpossibleGPSassistenhancement)
PTPdelivery:engineeredQoS/CoS orEVC/VPN,
shortestpath
PTPprofile:G.8265.1,layer3,unicast
1or2stepclock
Pros
Fullyprotectedsynchronization
Mobilenetworksyncisunaffected
bybackhaultechnologyorquality
Proventechnology,fullystandards
based
Uncertainperformance,noisybackhaul
Multipletechnologies,manyhops/paths,highpacketdelay
variation,3rd partyaccessvendors,etc.
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TimetransferisimpactedbyNetworkAsymmetry
Static(Physical)andNetworkLoadingAsymmetry
Keyphaserequirements network
asymmetry
impacts
phase
and
time,
not
frequency
Why:PTPprotocolisassumingthatOWD=RTD/2 neverthecase!
Static(physical)networkasymmetry
Mostnetworkscontainseveralasymmetries(withoutanyload)
- Transmissionspeedasymmetry(PECM@1GBPS, PECS@100MBPS~3sasymmetry)
- CablelengthasymmetrybetweenULandDL(hopbyhop)~1.3ns/ft(mediadependant,seevelocityof
propagationorVOP)
- VOPof differentonafiberfeed(hopbyhop)
- Modulation/bloc/FECencoding (MW,MMW,xDSL)asymmetry(whennotretraining)
- PHYandportasymmetryonaswitch/ SFPSFP+asymmetry 65nsto220nsrange(2perhop)
- TransmissionprotocolasymmetrybetweenPECMandPECS(VLANtagstrippedbyaswitch,oneQin
Qtagstripped,..)
Dynamic,Networkloadingasymmetrythatvarieswithtrafficcanberemovedup
to95%,dependingonqualityofclient
PseudoDynamic,changesoveralongperiodoftime,rerouting,networkfailures
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CORE AGGREGATION
Retrofitexistingequip.orbuildnewnetworkManagedEthernet,synchronousEthernet,boundaryclocks
ACCESS
Rebuildtoincludeboundaryclocksineverynetworkelement
PossiblyreviseMPLSnetworkdesignpractices
3.PhaseSynchronization:
G.8275.1
Full
On
Path
Support
BC
BCBC
BC
SyncE
SyncE
SyncE
SyncE
BCSyncE
MacroeNodeB
RbBCSyncE
BC BC BC
PTPGM
SyncE
PTPGM
SyncE SmallCell
AggregationMetroSmallCells
BC
SyncE
SyncE
SyncE SyncE
BCSyncE
BCSyncE
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3.PhaseSynchronization:
G.8275.1FullOnPathSupport
SynchronizationDistributionArchitecture
Syncequipmentanddeployment
Macroagg.site:highcapacityPTPgrandmaster,
SyncE,redundantequip.configurationand
networkprotected
Everynetworkelement:SyncEandBoundary
Clock
MacroeNodeB:PTPclient&highqualityrubidium
oscillatorforholdover
MetroSmallCell:highqualityPTPclient(with
possibleGPSassistenhancement)
PTPdelivery:
SyncEandBoundaryClocks
PTPprofile:preG.8275.1,layer2multicast
1stepclock
Cautions
Asymmetrymayrequirehopbyhop,
manualadjustmentstotimeoffset
QualityofPTPclientaffects
performance
NoupgradepathfromG.8265.1
frequencyarchitecture
DesignRules
SyncEthroughentiretransmission
pathforstability
BoundaryClockinalltransmission
networkelements
Retrofitexistingequip.orbuildnewnetworkManagedEthernet,synchronousEthernet,boundaryclocks
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G.8275.1DoesNotFitAllNetworks
BoundaryClockseverywhereisnotalwaysviable
Manynetworksarenotsuitable:diversetransporttechnologies,3rd party
backhaul,manyEthernetpathsandasymmetry,PON,bondedDSLand
VDSL2+,WiFi,weakPTPclients
Majorretrofitorreplacementofexistingnetworks.Notfinanciallyfeasible.
Manualhopbyhoptuningrequiredonsomelinks
eNodeB
PTPGM
PTPSlave
GNSSeverywhereisanalternative,but:
Vulnerable,needsbackup
Notfeasibleformanydeploymentsparticularlysmallcells
BoundaryClockineverynetworkelement
BC
SyncE
BC
SyncE
BC
SyncE
BC
SyncE
BC
SyncE
BC
SyncE
BC
SyncE
BC
SyncE
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Existingbackhaul,diversetechand/ornoisyMultipletechnologies,manyhops/paths,highPDV,3rd party,etc.
Providepartialonpathsupportwithadvancedboundaryclock
DeployPTPgrandmasteratorneartheedge
CORE ACCESSAGGREGATION
MacroeNodeB
SmallCellAgg.
MetroSmallCells
PTPGM
PTPGM
Microwave
HighPDV/3rd Party
4.PhaseSynchronization:
G.8275.2PartialOnPathSupportorEdgeGM
EdgeMasterClock
EdgeBC
G.8275.2:anewprofileforphaseG.8275.2:anewprofileforphase
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4.PhaseSynchronization:
G.8275.2Partial
On
Path
Support
or
Edge
GM
SynchronizationDistributionArchitecture
Syncequipmentanddeployment
Macroagg.site:highcapacityPTPgrandmaster,
redundantequip.configurationandnetworkprotected
Accessnetworksite:PTPmaster/BCwithGPS/GNSS
Smallcellaggregationsites:edgePTPgrandmasterwith
GNSS/GPS
MacroeNodeB:highqualityPTPclient&highquality
rubidiumoscillatorforholdover
MetroSmallCell:highqualityPTPclient(withpossible
GPSassistenhancement)
PTPdelivery:engineeredQoS/CoS orEVC/VPN,
shortestpath
PTPprofile:pre8275.2(G.8265.1profile),layer3
unicast
1or2stepclock
Pros
Savesdeployingmasteratthecell
site
Nonetworkretrofit:mobile
networksyncisunaffectedby
backhaultechnologyorquality
Asymmetrymitigation
Proventechnology,standards
based
Existingbackhaul,diversetechand/ornoisyMultipletechnologies,manyhops/paths,highPDV,3rd party,etc.
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Nochangeinnetworkhardware
OperatedoverexistingMPLS/CEnetwork
Preserves MPLS valueproposition
Nochangetobackofficeengineeringandoperationsprocesses
Mitigatesasymmetryasanissue
SyncnotdependentonembeddedNE
QualityofBCdesignnotanissue
AdvantagesoftheG.8275.2Architecture
LeveragesexistinginvestmentmadeinGPSateNodeBsites
CanleverageexistingPTPGMdeployments
CanleverageexistingGPSateNodeB
Complianttoexistingsyncstandards compatiblewithG.8265.1profile
SimpleandeasytodeployforallLTEarchitectures
PTPGM
EdgeMasterClock
Cost
effective
alternative:
deployaPTPmasteratorneartheedgeCost
effective
alternative:
deployaPTPmasteratorneartheedge
24ConfidentialCopyright2013
AutomaticPathAsymmetry
Correctionalgorithmsupplies
externalcorrectionfactoras
definedinIEEE1588
standard.
Algorithmlearnspath
asymmetriestothenorth
boundmasterevenwhile
systemmayusingGNSSasthe
primaryclocksource.
IntheeventofaGNSSfailure,
thesystemwilloperaterevert
tousingAsymmetrycorrected
PTP.
Featureavailablewiththe
TimeProvider2700PTPInput
SWLicense.
Path Re-arrangement (Ring Topology
AutomaticPathAsymmetryCorrection
RED:PPS
performancewith
asymmetry
correction.
Customernetworktestenvironment
BLUE:PPS
performance
withoutasymmetry
correction.
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ThisarchitecturehasbeenproposedtotheATIS/ITU
standardsbodies:
anewprofiletosupporttimeandphasedistributionover
existingdeployednetworkscompatiblewiththePTPprofile
forfrequencydistributiondefinedinG.8265.1
Contributionsubmittedby:Symmetricom,AT&T,Verizon,
SprintNextel,andTMobileUSA
G.8275.2ProfileforTimeandPhase
26ConfidentialCopyright2013
QualityofthePTPClientAffectsPerformance
Symmetricomclients,G.8261
testcases
Frequencyperformance:
MTIEbeneaththemask
(G.8261SECmask)
Phaseperformancetests:
consistentlyunder500ns
Consistencyoftheclients
Differencesinvendor
implementationsyielddifferent
results
Advancedalgorithms,highquality
oscillator,designimplementation
Advancedalgorithms,highquality
oscillator,designimplementation
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SynchronizationDistributionArchitecture
Syncequipmentanddeployment
Core:highcapacity, carriergradeNTPserver(orPTPgrandmaster);
redundantequip.configurationandnetworkprotected
Highqualityembeddedclientsinthesmallcell;withorwithoutGPSassist
ResidentialandEnterpriseIndoorSmallCells
WirelinenetworkbackhaulDSL,PON,Cable,MetroEthernet
WIRELINEACCESSNETWORKINTEROFFICEFACILITIES
PONONU
NTPServer
PTPGM
NTPServer
PTPGM
DSLmodemDSLAM
CablemodemCMTS
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Summary
LTEtechnologiesdrivenewrequirementsforsynchronization
Time/Phase
Backhaulnetworktechnologies,topologyandperformance
drivesynchronizationequipmentanddeploymentdecisions
Emergingboundaryclockbasedsolutionswillworkforsome
scenariosbutnotall
GNSS(GPS)requiresbackupandisnotfeasibleforsome
deploymentscenarios,especiallysmallcells
AnalternativearchitecturethatplacesaPTPmasterator
neartheedgeisthesolutionformanyofthesesituations
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Symmetricom,Inc.
2300OrchardParkway
SanJose,CA951311017
Tel:+14084287907
Fax:+14084286960
www.symmetricom.com
ThankYou.
SynchronizationDistributionArchitecturesforLTENetworks
JimOlsen
Jolsen@symmetricom.com
5126565371
30ConfidentialCopyright2013
AdditionalSlideMaterial
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LTEBaseStations
MetroSmallCells250mWto5W
(cumulativeunits)
500,000
1,000,000
1,500,000
2,000,000
2,500,000
2011A 2012E 2013E 2014E 2015E
TDDLTE
FDDLTE
LTEMacroStations(cumulativeunits)
Source:EJL
Source:HeavyReadingSource:EJL
200,000
400,000
600,000
800,000
1,000,000
1,200,000
2011A 2012E 2013E 2014E 2015E
TDDLTE
FDDLTE
MetroSmallCells
5Wto10W
(cumulativeunits)
32ConfidentialCopyright2013
LTESynchronizationRequirements
ApplicationFrequency
Network / AirPhase Note
LTE FDD 16ppb / 50ppb NA sameas2Gand 3G
LTE TDD 16ppb / 50ppb 1.5s 3kmcellradius
5s >3kmcellradius
LTEMBMS(LTEFDD<ETDD)
16ppb / 50ppb 10s intercelltimedifference
LTEAdvanced 16ppb / 50ppb 1.5to 5s see tablebelowfordetail
Note:Intercellcoordinationtimesarerequirementfordistributedtimeaccuracy.
LTEAcoversmultiple
techniquesratherthana
singletechnology.
Notallfeatureswill
deployedeverywhere,
leadingtodifferencesinreal
worldrequirements.
Figuresarestillindiscussion
bymembersofthe3GPP.
Frequencyrequirementsforearliergenerationsaresameasabove.GSM,UMTS,WCDMAdonothaveaphaserequirement.
CDMA2000phaserequirementis 3to10s.TDSCDMAphaserequirementis1.5s.
Smallcell/femtocells (UMTS,LTEFDD)requirefrequencyperformanceof100250ppbfortheairinterface.
LTEAdvanced TypeofCoordination Phase
eICIC enhancedIntercellInterferenceCoordination 1.5to 5sCoMP
Moderatetotight
ULcoordinatedscheduling 5s
DLcoordinatedscheduling 5s
CoMP
Verytight
DLcoordinatedbeamforming 1.5s
DLnoncoherentjointtransmission 5s
ULjointprocessing 1.5s
ULselectioncombining 1.5s
ULjointreception 1.5s
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InterCellInterferenceCoordination
R8 ICIC definesa limitedone
dimensionalfrequencybased
interferencemanagementfor
macronodes
R10 eICICintroducescontrolin
theHetNetonthethree
dimensionsofpower,phase,and
frequency
LTEAcanalsousemodifiedX2
adaptiveresourcepartitioningin
aTDDenvironmentalso(requiresprecisetime&phase
synchronization)
Blank subframes
Macro
DL
Pico
DL
Subframes reserved for macro
Subframes reserved for Pico
Time Domain Resources
Adaptive subframes
For Macro or Pico
Macro
DL
Pico
DL
Subframes reserved for macro
Subframes reserved for Pico
Time Domain Resources
eICIC = enhanced Inter-cell Interference Coordination
34ConfidentialCopyright2013
SettingandHolding
Twoaspectsofsynchronization
FrequencyFrequency PhasePhase
Deliverandset
frequency
Deliverandset
frequencyHold
frequency
Hold
frequency
Deliverandset
phase
Deliverandset
phase
Hold
phase
Hold
phase
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TypicalAttributesofHetNet Cells
Maxumberofusers
Deployment
Examplescenarios
Home
SmallCell
Home
SmallCell
Home,
Apartment
Indoor
16
Typicalcoverage
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