4_SynCan2013 Sync Distribution Architectures for LTE

8/10/2019 4_SynCan2013 Sync Distribution Architectures for LTE

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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


TheLTESynchronizationSolution

Onesolutiondoesnotfiteveryscenario.

SelectionofLTEtechnology(LTEFDD,LTETDD,LTEAdvanced)

drivesdifferentsynchronizationrequirements

Cellsitelocationsandmobilenetworkequipmentselectiondefine

whatcanandcannotbedone(particularlyforsmallcells)

Backhaulnetworktechnologies,topologyandperformancedrive

decisionsforsyncequipmentselectionanddeploymentlocations

NewEdgeMasterClocks,deployednearthenetworkedge,

enableavarietyofsynchronizationdistributionarchitectures

foravarietyofnetworkscenarios


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Synchronization,StandardsandRequirements


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!


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&LTETDD)

16ppb / 50ppb 10s intercelltimedifference

LTEAdvanced 16ppb / 50ppb 1.5sto 5s Indiscussionbymembers

ofthe3GPP

New 1.5sto 5sphasetimingrequirementsrequirenewsynchronizationdistributionarchitectures

New 1.5sto 5sphasetimingrequirementsrequirenewsynchronizationdistributionarchitectures


SynchronizationDistributionArchitectures

forLTENetworks


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3Guidelines

2.Protectyoursyncforserviceassurance

GNSS,PTP&Stablefrequencysource

Highperformanceholdover

3.DeployPTPGrandmasterwherethenetworkneedsitforaccuracy

Backhaulsupportsaccuracy:allowsdeploymentclosertothecore

Noisy,highPDVnetwork:requiresdeploymentatorneartheedge

1.Useanindependentsourceforsync

Bestinclasssolutions

Efficientoperationinamultivendornetwork


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



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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G.8265.1EdgeArchitecture

Uncertainperformance,noisybackhaulMultipletechnologies,manyhops/paths,highpacketdelay

variation,3rd partyaccessvendors,etc.

SetfrequencywithPTPorGNSS

HoldfrequencywithPTPorGNSS


MacroeNodeB

SmallCellAgg.

MetroSmallCells

PTPGM

PTPGM

PON

ONU

Microwave

DSLmodemDSLAM

HighPDV/3rd Party

EdgeGM

EdgeGM

G.8265.1profile



G.8265.1

Edge

Architecture




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


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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G.8275.1FullOnPathSupport




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


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


MacroeNodeB

SmallCellAgg.

MetroSmallCells

PTPGM

PTPGM

Microwave

HighPDV/3rd Party


G.8275.2PartialOnPathSupportorEdgeGM

EdgeMasterClock

EdgeBC

G.8275.2:anewprofileforphaseG.8275.2:anewprofileforphase



G.8275.2Partial

On

Path

Support

or

Edge

GM




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


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


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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Core:highcapacity, carriergradeNTPserver(orPTPgrandmaster);

redundantequip.configurationandnetworkprotected

Highqualityembeddedclientsinthesmallcell;withorwithoutGPSassist

ResidentialandEnterpriseIndoorSmallCells

WirelinenetworkbackhaulDSL,PON,Cable,MetroEthernet

WIRELINEACCESSNETWORKINTEROFFICEFACILITIES

PONONU

NTPServer

PTPGM

NTPServer

PTPGM

DSLmodemDSLAM

CablemodemCMTS


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

[email protected]

5126565371


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)


LTESynchronizationRequirements

ApplicationFrequency

Network / AirPhase Note

LTE FDD 16ppb / 50ppb NA sameas2Gand 3G

LTE TDD 16ppb / 50ppb 1.5s 3kmcellradius

5s >3kmcellradius

LTEMBMS(LTEFDD&LTETDD)

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


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

Documents

4_SynCan2013 Sync Distribution Architectures for LTE