© 2014 Microsemi Corporation. COMPANY PROPRIETARY 1 Power Matters. TM Achieving Phase Accuracy for...

© 2014 Microsemi Corporation. COMPANY PROPRIETARY 1

Power Matters.TM

Achieving Phase Accuracyfor LTE-A SynchronizationField Measurement Results

Power Matters.TM 2© 2014 Microsemi Corporation. COMPANY PROPRIETARY

Overview• Frequency, Time, and Phase Synchronization• IEEE 1588 Precision Time Protocol Profiles• ITU Standards and Deployment Models

Achieving Phase Accuracy in the Field• Field Testing Overview• Specific test cases• Field Test Results

Conclusions

Agenda


TA=1/fA

TB=1/fB

fA=fB

Frequency Synchronization

A

B t

t

Frequency, Time and Phase Synchronization

TA=1/fA

TB=1/fB

fA=fB

Phase Synchronization

A

B t

t

01:00:00TA=1/fA

TB=1/fB

fA=fB

Time Synchronization01:00:10

01:00:00 01:00:10

A

B

t

t

E1/T1, SyncE, PTP, GNSS, NTP, 10Mhz, 1PPS

PTP, GNSS, NTP, 1PPS

PTP, GNSS, NTP


Mobile Wireless Synchronization Requirements

Mobile Technology Frequency Input into Base Station

Inter Cell Phase Alignment

N/A

± 1.5µs

± 1.5µs

± 0.5 to ± 1.5µs

± 1.5µs

± 1 to ± 32µs

16 ppbFDD

LTE-TDD

eICIC

CoMP

MBSFN

MBMS

LTE-A


IEEE 1588-2008 Profiles

IEEE 1588-2008 …• -2008 defined for all applications …

barrier to interoperability• profiles define application related

features from the full specification, enabling interoperability

Default ProfileDefined in Annex J. of 1588 specificationLAN/Industrial Automation Application (v1)

Power ProfileDefined by IEEE PSRC (C37.238)Substation LAN Applications

Telecom ProfileDefined by ITU-T (G.8265.1, G.8275)Telecom WAN Applications


PTP (IEEE 1588) Routing Options

Multicast Grandmaster broadcasts PTP packets

to a Multicast IP address Switches/Routers…

• With IGMP snooping, forwards multicast packets to subscribers

• Else traffic broadcast to all ports Multicast Sync Interval:

Fixed rate, example 16Hz

Unicast Grandmaster sends PTP packets

directly to PTP slaves Switches/Routers forward PTP packets

directly to slaves Unicast Sync Interval; Telecom Profile:

• User defined Sync interval up to 128Hz

• Many subscribers supported

Multicast (1:group) Unicast (1:1)


1. Originate Time Stamp

How Time Offsets are Corrected in Time Transfer

Client

1. Originate Time Stamp2. Receive Time Stamp1. Originate Time Stamp2. Receive Time Stamp3. Transmit Time Stamp

1. Originate Time Stamp 2. Receive Time Stamp3. Transmit Time Stamp4. Client Time Received

ClientTime = (Receive Time – Originate Time) + (Transmit Time – Client Time Received)Offset 2

Assumes symmetric path latency (delay) for outbound and return paths

Server


• Automatic Path Asymmetry Correction algorithm supplies external correction factor as defined in IEEE 1588 standard.

• Algorithm learns path asymmetries to the north-bound master … even while system may using GNSS as the primary clock source.

• In the event of a GNSS failure, the system will operate revert to using Asymmetry corrected PTP.

• Feature available with the TimeProvider 2700

• Will be added to G.8273.4 APTS

Path Re-arrangement (Ring Topology

Automatic Path Asymmetry Correction

RED: PPS performance with asymmetry correction.

Customer network test environment

BLUE: PPS performance without asymmetry correction.


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

Structure of ITU-T Sync Requirements

G.8265.1: Precision Time Protocol Telecom Profile for Frequency Synchronization

G.8275.1: PTP Telecom Profile for Time/Phase Synchronization, Full OPS

Basic Aspects

Clocks

Methods

ProfilesG.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/Phase Full on Path SupportNetwork

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.8275.2: PTP Telecom Profile for Time/Phase Synchronization, Partial OPS

G.8271.2: Network Requirements for Time/Phase Partial On Path Support

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.8273.4: 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.8273.3: Telecom Transparent Clock (T-TC)


LTE FDD Frequency, Managed Ethernet Backhaul G.8265.1 Architecture

Managed Ethernet Backhaulconsistent, known performance

CORE ACCESSAGGREGATION

PTP slave/client device

Macro eNodeB

• Set frequency with PTP (GNSS/GPS primary source)• 10 hops with QoS on PTP flow• No on path support (BC/TC) required

PTP GM

PTP GM

CES/PWE IWF

GPON

Base Station

Media Gateway


Retrofit Existing Backhaul or New Build

Managed Ethernet, Synchronous Ethernet, Boundary Clocks

CORE ACCESSAGGREGATION

• Set time/phase with PTP (GNSS at primary source)• SyncE and Boundary Clock in every node for asymmetry

mitigation

LTE-A, TDD Phase, Retrofitted or New Ethernet Backhaul - G.8275.1 Architecture

BC

BC BC BC

BCBCBC

BC

BC

PTP GMSyncE

SyncE

SyncE

SyncE SyncE

SyncE

SyncE

SyncE

SyncE

SyncE

Macro eNodeB

RbBCSyncE

PTP GMSyncE

BC BC BC

Small CellAgg.

MetroSmall Cells

BCSyncE


LTE-A, TDD Phase, Overlay Existing Backhaul G.8275.2 Architecture

AGGREGATION

• Set time/phase in macro/small cells with GMC at edge (asymmetry not an issue)

• Hold time/phase with GMC from MSC using asymmetry compensation

Macro eNodeB

CORE

PTP GM

PTP GM

Existing Backhaul

Edgemaster Overlay with Asymmetry Correction

PTP GM

• Once time/phase is set asymmetry is not an issue

ACCESS

PONONUOLT

Microwave

Ethernet

PTP GM

Small CellAggregation

MetroSmall Cells

DSLmodem DSLAM

Macro eNodeB


Achieving Phase Accuracyin the Field


Objective: Confirm that PTP can be used to synchronize eNodeBs • Test Case 1: Partial On-Path Support without GNSS support• Test Case 2: Partial On-Path Support

with GNSS reference on the Edge (as per ITU G.8275.2)

• Test Case 3: Partial On-Path Support with loss of GPS at the Edge (with Asymmetry Correction).

• Test Case 4: Partial On-Path Support 3rd party embedded PTP in CSR

Satisfy LTE-A Phase Requirements ±1.5µs (3µs total) Measure PTP Phase Performance to the eNodeB. Measure Packet Delay Variation (PDV) Backhaul Path

Field Test – Overview


Path PDV Characteristics

Direction PD Min PD Max PD Range PD Mean

Forward 647us 14,500us 13,900us 709us

Reverse 629us 989us 360us 663us


Path PDV Characteristics (Zoom)

Direction PD Min PD Max PD Range PD Mean

Forward 647us 14,500us 13,900us 709us

Reverse 629us 989us 360us 663us


Path PDV Characteristics ( FW floor Zoom)

Mean FPP ( 200sec window) : 10us – 5.88%

100us – 81.94%


Path PDV Characteristics ( RV floor Zoom)

Mean FPP ( 200sec window) : 10us – 2.53%

100us – 99.86%


Phase Performance Comparison

TC 2: Partial On-PathTP2700 with GNSS input

TC 3: Partial On-Path (Loss of GPS)TP2700 with Asymmetry compensation

TC 1: Partial On-PathTP2700 with PTP input only (BC)

TC 4: Partial On-Path Embedded in 3rd party CSR


Test Case 1: Partial On-Path Support without GNSS support

TP-5000PDV Probe1PPS & 10MHz Reference

PTP Slave

1PPS Ref

10MHz Counter Ref

TimeMonitorData collectionand analysis

GPS

Ethernet Backhaul Network

MSOeNB Site

Counter

1PPS Out

TP-2700 w/o GPS

PTP – Reverse direction

Router or Switch

PTP – Forward direction

CSR

TP-5000 GM

GPS


TC1 Phase Performance

7.86usp-p


Test Case 2: Partial On-Path Support As per ITU G.8275.2

Wireless Ethernet Backhaul Network

MSO


Router or Switch


TP-5000 GM

GPS


PTP Slave

1PPS Ref

10MHz Counter Ref


GPS

eNB Site

Counter

1PPS Out

TP-2700 w/ GPS

CSR



567nsp-p


Test Case 3: Partial On-Path Support Loss of GPS at the Edge (Asymmetry Compensation)


MSO


Router or Switch


TP-5000 GM

GPS


eNB withPTP Slave

1PPS Ref

10MHz Counter Ref


GPS

eNB Site

Counter

1PPS Out

TP-2700 w/ GPS

CSR

X


TC2 to TC3 – GNSS to PTP fallback



1.74usp-p


Test Case 4: Partial On-Path Support 3rd party embedded PTP in CSR


MSO


Router or Switch


TP-5000 GM

GPS


eNB withPTP Slave

1PPS Ref

10MHz Counter Ref


GPS

eNB Site

Counter

1PPS Out

CSR



1.25usp-p


All TP2700 Test Cases met and exceeded ±1.5µs (3µs total) for LTE-A phase performance.

Combining GNSS and PTP with Asymmetry correction give fastest reference switchover and good performance.

Many embedded PTP clients fail to compensate the network asymmetry. Phase accuracy isn’t the only important parameter!

Field Test – Summary


Eran GilatEMEA, System Sales [email protected]+972.52.342.4718

Thank You

mailto:[email protected]

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