Using a hybrid environment with SyncE and 1588v2 to provide a

better platform for mobile backhaul

Hans Sjöstrand – Product Manager, Transmode Systems AB

Chris Farrow – Technical Services Manager, Chronos Technology Ltd

Trends in mobile networks impact mobile backhaul

• Strong need to enhance and improve existing mobile backhaul

• To fulfill capacity requirements, new technologies are required

• More stringent accuracy requirements needed to support new functionality, like LTE coordinated multipoint (CoMP) and enhanced inter-cell interference coordination (eICIC)

– Synchronization becoming one of the most important criteria

– Phase and time synchronization is required for LTE-Advanced

• SLA assurance and end-to-end performanceis important

• Support for multiple radio access architectures (RAA)

LTE synchronization requirementsApplication Frequency

Network / Air

Phase Note

LTE – FDD 16 ppb / 50 ppb N/A

LTE – TDD 16 ppb / 50 ppb ± 1.5 μs

± 5 μs

≤3 km cell radius

>3km cell radius

LTE MBMS (LTE-FDD & LTE-TDD)

16 ppb / 50 ppb ± 10 μs inter-cell time difference

LTE- Advanced 16 ppb / 50 ppb ± 1.5 to 5 μs Details in table

LTE-Advanced Type of Coordination Phase

eICIC enhanced Inter-cell Interference Coordination ± 1.5 to 5 μs

CoMP

Moderate to tight

UL coordinated schedulingDL coordinated scheduling

± 5 μs

± 5 μs

CoMP

Very tight

DL coordinated beamformingDL non-coherent joint transmission

± 1.5 μs

± 5 μs

UL joint processing

UL selection combining

UL joint reception

± 1.5 μs

± 1.5 μs

± 1.5 μs

Frequency requirements for earlier generations are same as above. GSM, UMTS, W-CDMA do not have a phase requirement. CDMA2000 phase requirement is ±3 to 10 μs.

LTE-A covers multiple techniques rather than a single technology.

Not all features will be deployed everywhere, leading to differences in real world requirements.

Figures are still in discussion by members of the 3GPP. Down to ± 0.5 μs accuracy.

Solve the nanosecond challenge

SyncEIP MPLS Network

ROADM

λ

ROADM

λ

ROADM

λ

ROADM

λ

PRC / GM

Hybrid Mode SC

T-TC

T-TC

T-TC

T-TC

T-TC T-TC

T-TC

T-BC T-BC

T-TC

Solutions Tools

1Make the network completely transparent

from clock perspective

Transparent Clock

2 Bring a PRC clock to the cell site SyncE Hybrid mode

Transparent Clock

Output buffer

Output buffer

Corr: + 1231.662356

Corr: + 861.452344

Not a clock at all.

TC Compensates for delays

in NEs for PTP packets

Advantages:

• No configuration required

• Immediate setup times

• No interoperability problems

• Handles asymmetry

Packet Delay Variation

10 Hop network PDV with 20% load Same network PDV with T-TC onpath support.

0.2 us16 us

T-SC

Each hop contributing

with traffic generating PDV

in each output

GbE GbEGbE GbE GbE GbE GbE GbE GbE GbE

10G 10G 10G 10G 10G 10G 10G 10G 10G

GM

Achieve ±40 ns in worst Traffic Case

G.8265.1 TC13. varying traffic load, forward (80% to 20%) and reverse (10% to 50%).

Max Phase error ~50 us

Max Phase error ~80 ns

No onpath support With Network Transparency

Synchronous Ethernet

Advantages:

• Close to the metal

• Scales without problem

• Local repair

• Stability

SyncE provides outstanding Network Synchronization

Old TDM

SyncE

G.823

PRC

Customer statement after live field trial

- now providing a far better sync feed than <mobile operator> have ever achieved using E1or ATM transport …..

SyncE Hybrid Mode

SyncE

SyncE assisted

1588 Slave Clock

SyncE Frequency1588 PTP time

PRC / GM

The long term stable

PRC quality stabilized

clock makes PTP Slave

servo job easier.

Chronos - Test Setup

Paragon 1

EX

MP

1G

1G

Paragon 2

EX

MP

1G

1G

PTPv2 GMSyncE Master

PTPv2 + SyncE @ 1GOptical Single Mode LX

PTPv2 + SyncE Slave

G.8262 - TC15G.8262 - TC13

PTPv2 Slave NID

NID1G

PTPv2 + SyncE @ 100MElectrical RJ45

PTPv2 @ 100MElectrical RJ45

PTPv2 @ 1GOptical Single Mode LX

G.8271.1 requirements

G.8261 TC15

(PTP) vs. (SyncE + PTP) - TIE

(PTP) vs. (SyncE + PTP) - MTIE

Microwave profile - TIE

Microwave profile - MTIE

IEEE 1588 PTP Hybrid mode assisted by SyncE

Measurements of actual Phase error in G.8271.1

Traffic Matrix with a commercial Slave clock

Red line shows 1588 Slave clock phase error. Blue line shows EMXPII SyncE assisted 1588 Slave clock phase error

1588 Slave clock phase error:Phase ~2.9 μs

SyncE assisted 1588 Slave clock phase error:Phase ~300 ns

Test Results Summary

EndEquipment Environment SyncEBenefit

VendorA G.8265.1TC13 Clearlyvisible

VendorB G.8265.1TC13 Orderofmagnitudeimprovement

VendorB G.8265.1TC15 Clearlyvisible

VendorB RealMicrowaveNetwork

Largeimprovementinlong-termaccuracy

To effectively manage large scale sync networks you need two things:

Independent

Measurement and Monitoring

Comprehensive network

awareness and end to end path

management

Ability to cost effectively

manage large scale Phase

sync. network

All sync events available to the NMS/OSS layer

NMSX

1P

PS

2 M

Hz

SNMP

Syn

cE

2 M

Hz

X

SNMP

SyncMonitor

OSS

GPS

GPS

Sync probe

Transport vendor & independent sync monitoring combined

OSS PlatformHPOV, NetCool etc. etc.

Sync ProbesTransport

SyncSSU/GM Wireless

Wrap up

• SyncE delivers a PRC-traceable clock to the edge

– Used as a stable timebase for packet time-stamping & delay measurement

– Increasing the performance over PTP only

• TC15 open to differing interpretation

• Better QoSync improves network function