Transcript Power Matters. TM

Power Matters.TM
Achieving Phase Accuracy
for LTE-A Synchronization
Field Measurement Results
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
1
Agenda
 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
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
2
Frequency, Time and Phase Synchronization
E1/T1, SyncE, PTP, GNSS, NTP, 10Mhz,
1PPS
Frequency Synchronization
TA=1/fA
A
t
TB=1/fB
B
t
fA=fB
Phase Synchronization
PTP, GNSS, NTP, 1PPS
TA=1/fA
A
t
TB=1/fB
B
t
fA=fB
Time Synchronization
01:00:00
PTP, GNSS, NTP
01:00:10
TA=1/fA
A
t
TB=1/fB
B
fA=fB
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
t
01:00:00
01:00:10
Power Matters.TM
3
Mobile Wireless Synchronization
Requirements
Mobile Technology
Frequency Input
into Base Station
Inter Cell Phase
Alignment
FDD
16 ppb
N/A
LTE-TDD
± 1.5µs
eICIC
± 1.5µs
CoMP
± 0.5 to ± 1.5µs
LTE-A
MBSFN
± 1.5µs
MBMS
± 1 to ± 32µs
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
4
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
Power Profile
Defined by IEEE PSRC (C37.238)
Substation LAN Applications
Telecom Profile
Defined by ITU-T (G.8265.1, G.8275)
Telecom WAN Applications
Default Profile
Defined in Annex J. of 1588 specification
LAN/Industrial Automation Application (v1)
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
5
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:
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
Fixed rate, example 16Hz
Multicast (1:group)
Unicast (1:1)
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
7
How Time Offsets are Corrected
in Time Transfer
Client
Server
1. Originate Time Stamp
2. Receive Time Stamp
3. Transmit Time Stamp
4. Client Time Received
1. Originate Time Stamp
2. Receive Time Stamp
3. Transmit Time Stamp
Client
Time = (Receive Time – Originate Time) + (Transmit Time – Client Time Received)
Offset
2
Assumes symmetric path latency (delay) for outbound and return paths
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
10
Automatic Path Asymmetry Correction
• 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.
Customer network test environment
Path Re-arrangement (Ring Topology
• 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
BLUE: PPS
performance
without asymmetry
correction.
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
RED: PPS
performance with
asymmetry
correction.
Power Matters.TM
11
Structure of ITU-T Sync Requirements
G.8260: Definitions and Terminology for
Synchronization in Packet Networks
Definitions / Terminology
Basic Aspects
Network
Requirements
Clocks
Frequency
Time/Phase
G.8261: Timing and Synchronization Aspects in Packet
Networks (Frequency)
G.8271: Time and Phase Synchronization Aspects in
Packet Networks
G.8271.1: Network Requirements for Time/Phase
Full on Path Support
G.8261.1: PDV Network Limits Applicable to PacketBased Methods (Frequency)
G.8261.2: Reserved for future use
G.8271.2: Network Requirements for Time/Phase
Partial On Path Support
G.8262: Timing Characteristics of a Synchronous
Ethernet Equipment Slave Clock (EEC)
G.8272: PRTC (Primary Reference Time Clock)
Performance
G.8263: Timing Characteristics of Packet-Based
Equipment Clocks (PEC)
G.8273: Packet-Based Equipment Clocks for
Time/Phase: Framework
G.8273.1: Telecom Grandmaster (T-GM)
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)
Methods
Profiles
G.8264: Distribution of Timing Information through
Packet Networks
G.8274: Reserved for future use
G.8265: Architecture and Requirements for PacketBased Frequency Delivery
G.8275: Architecture and Requirements for PacketBased Time and Phase Delivery
G.8275.1: PTP Telecom Profile for
Time/Phase Synchronization, Full OPS
G.8265.1: Precision Time Protocol Telecom
Profile for Frequency Synchronization
G.8275.2: PTP Telecom Profile for
Time/Phase Synchronization, Partial OPS
G.8265.2 PTP Telecom Profile for Frequency #2
agreed
ongoing
options
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
12
LTE FDD Frequency, Managed Ethernet
Backhaul G.8265.1 Architecture
Managed Ethernet Backhaul
consistent, known performance
CORE
AGGREGATION
ACCESS
PTP GM
Macro eNodeB
PTP slave/client device
CES/PWE IWF
PTP GM
GPON
Base Station
• Set frequency with PTP (GNSS/GPS primary source)
• 10 hops with QoS on PTP flow
• No on path support (BC/TC) required
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Media Gateway
Power Matters.TM
13
LTE-A, TDD Phase, Retrofitted or New
Ethernet Backhaul - G.8275.1 Architecture
Retrofit Existing Backhaul or New Build
Managed Ethernet, Synchronous Ethernet, Boundary Clocks
CORE
ACCESS
AGGREGATION
PTP GM
SyncE
BC
BC
SyncE
BC
SyncE
SyncE
BC
BC
SyncE
SyncE
PTP GM
SyncE
BC
SyncE
BC
SyncE
Rb
Macro eNodeB
BC
SyncE
BC
BC
SyncE
SyncE
BC
BC
BC
BC
SyncE
Small Cell
Agg.
Metro
Small Cells
• Set time/phase with PTP (GNSS at primary source)
• SyncE and Boundary Clock in every node for asymmetry
mitigation
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
14
LTE-A, TDD Phase, Overlay Existing
Backhaul G.8275.2 Architecture
Existing Backhaul
Edgemaster Overlay with Asymmetry Correction
CORE
AGGREGATION
ACCESS
Ethernet
PTP GM
PTP GM
Macro eNodeB
Microwave
Macro eNodeB
PON
OLT
ONU
Small Cell
Aggregation
DSL
PTP GM
modem
DSLAM
• 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
PTP GM
Metro
Small Cells
• Once time/phase is set
asymmetry is not an issue
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
15
Achieving Phase Accuracy
in the Field
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
16
Field Test – Overview
 Objective:
Confirm that PTP can be used to synchronize eNodeBs
• Test Case 1:
• Test Case 2:
Partial On-Path Support without GNSS support
Partial On-Path Support
with GNSS reference on the Edge
(as per ITU G.8275.2)
• Test Case 3:
• Test Case 4:
Partial On-Path Support
with loss of GPS at the Edge
(with Asymmetry Correction).
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
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
17
Path PDV Characteristics
Direction
PD Min
PD Max
PD Range
PD Mean
Forward
647us
14,500us
13,900us
709us
Reverse
629us
989us
360us
663us
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
19
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
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
20
Path PDV Characteristics ( FW floor Zoom)
Mean FPP ( 200sec window) :
10us – 5.88%
100us – 81.94%
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
21
Path PDV Characteristics ( RV floor Zoom)
Mean FPP ( 200sec window) :
10us – 2.53%
100us – 99.86%
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
22
Phase Performance Comparison
TC 1: Partial On-Path
TP2700 with PTP input only (BC)
TC 2: Partial On-Path
TP2700 with GNSS input
TC 3: Partial On-Path (Loss of GPS)
TP2700 with Asymmetry compensation
TC 4: Partial On-Path
Embedded in 3rd party CSR
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
23
Test Case 1: Partial On-Path Support
without GNSS support
eNB Site
MSO
GPS
TP-5000
PDV Probe
1PPS & 10MHz Reference
GPS
CSR
PTP Slave
TP-5000 GM
1PPS Out
1PPS
Ref
10MHz
Counter
Ref
Ethernet Backhaul Network
TP-2700 w/o GPS
PTP – Forward direction
PTP – Reverse direction
Counter
TimeMonitor
Data collection
and analysis
Router or Switch
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
24
TC1 Phase Performance
7.86usp-p
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
25
Test Case 2: Partial On-Path Support
As per ITU G.8275.2
eNB Site
MSO
GPS
TP-5000
PDV Probe
1PPS & 10MHz Reference
GPS
CSR
PTP Slave
TP-5000 GM
1PPS Out
Wireless Ethernet Backhaul Network
TP-2700 w/ GPS
PTP – Forward direction
PTP – Reverse direction
1PPS
Ref
10MHz
Counter
Ref
Counter
TimeMonitor
Data collection
and analysis
Router or Switch
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
26
TC2 Phase Performance
567nsp-p
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
27
Test Case 3: Partial On-Path Support
Loss of GPS at the Edge (Asymmetry Compensation)
eNB Site
MSO
GPS
TP-5000
PDV Probe
1PPS & 10MHz Reference
GPS
CSR
eNB with
PTP Slave
TP-5000 GM
1PPS Out
Wireless Ethernet Backhaul Network
1PPS
Ref
10MHz
Counter
Ref
X
TP-2700 w/ GPS
PTP – Forward direction
PTP – Reverse direction
Counter
TimeMonitor
Data collection
and analysis
Router or Switch
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
28
TC2 to TC3 – GNSS to PTP fallback
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
29
TC3 Phase Performance
1.74usp-p
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
30
Test Case 4: Partial On-Path Support
3rd party embedded PTP in CSR
eNB Site
MSO
GPS
TP-5000
PDV Probe
1PPS & 10MHz Reference
GPS
CSR
eNB with
PTP Slave
TP-5000 GM
1PPS Out
1PPS
Ref
10MHz
Counter
Ref
Wireless Ethernet Backhaul Network
Counter
PTP – Forward direction
PTP – Reverse direction
TimeMonitor
Data collection
and analysis
Router or Switch
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
31
TC4 Phase Performance
1.25usp-p
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
32
Field Test – Summary
 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!
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
33
Thank You
Eran Gilat
EMEA, System Sales Engineer
[email protected]
+972.52.342.4718
© 2014 Microsemi Corporation. COMPANY PROPRIETARY
Power Matters.TM
35