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Smooth Evolution Path from Legacy to NGN Synchronization
Dominik Schneuwly
November 6th, 2014
© 2014 ADVA Optical Networking. All rights reserved.2
Outline
• Drivers of the evolution
• Dimensions of the evolution
• Evolution starting points
• Evolution phases and end points
• Evolution path examples
• Conclusions
© 2014 ADVA Optical Networking. All rights reserved.3
Driver of the evolution
• Network technology evolution from TDM to packet-switchednetworks, and from fixed to fixed & mobile end sytems
• Synchronization in the past:• Driver: TDM switching (telephony) and transmission (SDH)
• Reasons: limit under- and overflowing of frame buffers,
allow crossconnecting (SDH)
• Requirements: frequency, accuracy 1·10-11 (relative freq. acc.)
• Synchronization at present and in the future:• Driver: mobile base stations, e.g. 2G BTS, 3G Node B, 4G eNB
• Reasons: successful call handover
efficient use of sparse spectrum & channel capacity
etc.
• Requirements: frequency (1.6E-8) and phase (1.5 μs ⇾ hundreds ns)
© 2014 ADVA Optical Networking. All rights reserved.4
Dimensions of the evolution
• Change in synchronization needs• Old: frequency for the entire network (1E-11)
• New: frequency (1.6E-8) and phase (1.5 μs ⇾ hundreds ns) for the network edge
• Change in network technology• Old: TDM networks (PDH, SDH)
• New: packet-switched networks
• Ethernet, Synchronous Ethernet (SyncE)
• IP, IP/MPLS
• Etc.
• Change in synchronization technology• Old: SDH/SONET, E1/T1 over PDH
• New: SyncE, PTP (IEEE 1588 v2)
Synchronizationtechnology
Synchronizationneeds
Networkcontext
© 2014 ADVA Optical Networking. All rights reserved.5
Once more: frequency, phase and time-of-day
t
t
Clock signal of system A
Clock signal of system B ! !!
t
t
Time signal of system A
Time signal of system B
14/01/0008:34:56
14/01/0008:34:57
14/01/0008:34:55
14/01/0008:34:55
14/01/0008:34:56
14/01/0008:34:57
System A System B
t
t
Clock signal of system A
Clock signal of system B
TA = 1 / fA
TB = 1 / fB
fA = fB• Frequency synchronization
• Phase synchronization
• Time-of-Day synchronization
© 2014 ADVA Optical Networking. All rights reserved.6
Application Radio Interface Backhaul
Frequency Phase Frequency Phase
CDMA 2000 ±50ppb ±3 to 10µs GPS GPS
GSM ±50ppb n/a ±16ppb n/a
WCDMA ±50ppb n/a ±16ppb n/a
LTE (FDD) ±50ppb n/a ±16ppb n/a
LTE (TDD) ±50ppb ±1.5µs ±16ppb ±1.1µs
LTE-A MBMS ±50ppb ±1 to 5µs ±16ppb±1µs
(G.8271)
LTE-A CoMPLTE-A CoMP JT
±50ppb±1 to 5µs± 0.5µs
±16ppb±1.1µs
< 0.5µs (?)
LTE-A eICIC ±50ppb ±1 to 3µs ±16ppb ±1.1µs
Frequency and phase synch. requirements
MBMS: Multimedia Broadcast Multicast Services CoMP: Coordinated MultipointeICIC: enhanced Inter-Cell Interference Coordination JT: Joint Transmission
© 2014 ADVA Optical Networking. All rights reserved.7
Starting point 1: central PRC
PRC
SDH
SSUSSU
SSUSSU
SSU
• Frequency synchronizationwith accuracy = 1E-11
• Generation: central PRC, typically atomic Cesiumclock
• Distribution: SDH, physicallayer; sometimes E1/T1 in «last mile»
© 2014 ADVA Optical Networking. All rights reserved.8
Starting point 2: distributed PRCs
SDHSubnetwork
PRC
SDHSubnetwork
PRC
SDHSubnetwork
PRC
• Frequency synchronization with accuracy = 1E-11
• Generation: distributed PRCs, typically GNSS receivers
• Distribution: SDH, physical layer; sometimes E1/T1 in «last mile»
© 2014 ADVA Optical Networking. All rights reserved.9
Transition phases
• Main transition phases:
• A: Frequency over TDM network• SDH/SONET
• B: Frequency over packet network• SyncE
• PTP / No Timing Support (G.8265.1)
• C: Phase over packet network• PTP / Full Timing Support (G.8275.1) with SyncE
• PTP / Full Timing Support (G.8275.1) without SyncE (ITU-T: «ffs»)
• PTP / Assisted Partial Timing Support (G.8275.2)
A B C
(less common)
© 2014 ADVA Optical Networking. All rights reserved.10
Transition A → B
B / A SDH & PDH
SyncE X
G.8265.1 X
Transition B → C
C / B SyncE G.8265.1
G.8275.1 X X
G.8275.2 X X
Many evolution scenarios
Transitions A → B → C:
SDH & PDH → SyncE → G.8275.1
SDH & PDH → SyncE → G.8275.2
SDH & PDH → G.8265.1 → G.8275.1
SDH & PDH → G.8265.1 → G.8275.2
© 2014 ADVA Optical Networking. All rights reserved.11
There are more evolution scenarios than that!
• Already mentioned: Starting point (SDH & PDH) can be withcentralized or with decentralized PRCs
• There are multiple mobile systems (2G, 3G, 4G); evolutionscenarios may be different for each of them
• Multiple network ownerships (mobile operator, transport provider, etc.)
• Networks with equiment from multiple vendors: differentequipment roadmaps
• Some operators use CES/PWE for their 2G BTS (PDH over packetnetwork)
• And we haven’t mentioned WDM systems in conjunction withphase synchronization …
• Etc., etc.
© 2014 ADVA Optical Networking. All rights reserved.12
Evolution example 1a: SDH & PDH → SyncE → G.8275.1
Leverage existing PRC and SSUs
SSU
PRC
SDHor
SyncE
SyncE
SSU
PRC
SDH
SDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toSyncE
© 2014 ADVA Optical Networking. All rights reserved.13
Evolution example 1a: SDH & PDH → SyncE → G.8275.1
Leverage existing PRC and SSUs, just add cards to SSUs for phase
SSU
PRC
SDH
SyncE
SSU
PRC
SDH
SDH & PDH
SSU
SyncE
GNSScard
T-GMcard
GNSS
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
G.8275.1
DeployBoundary Clocks
Add cards
Upgrade toPTP Slave
Upgrade toSyncE
Core
© 2014 ADVA Optical Networking. All rights reserved.14
Evolution example 1b: keep PRC for phase holdover
Leverage existing PRC and SSUs, just add cards to SSUs for phase
SSU
PRC
SDHor
SyncE
SyncE
SSU
PRC
SDH
SDH & PDH
SSU
SyncE
GNSScard
T-GMcard
GNSS
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
G.8275.1
DeployBoundary Clocks
Add cards
Upgrade toPTP Slave
Upgrade toSyncE
PRC
SDHor
SyncEFor Holdover:frequency holds phase & time
© 2014 ADVA Optical Networking. All rights reserved.15
Evolution example 1c: starting with decentralized PRCs
Leverage existing GNSS/SSUs, just add T-GM card to SSUs for phase
SyncESDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toSyncE
GNSScard
GNSS
SSUGNSScard
GNSS
SSU
Local PRC Local PRC
© 2014 ADVA Optical Networking. All rights reserved.16
Evolution example 1c: starting with decentralized PRCs
Leverage existing GNSS/SSUs, just add T-GM card to SSUs for phase
SyncESDH & PDH
SSU
SyncE
GNSScard
T-GMcard
GNSS
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
G.8275.1
DeployBoundary Clocks
Add card
Upgrade toPTP Slave
Upgrade toSyncE
GNSScard
GNSS
SSUGNSScard
GNSS
SSU
Local PRC Local PRC Local PRTC
© 2014 ADVA Optical Networking. All rights reserved.17
Evolution example 2a: SDH & PDH → SyncE → G.8275.2
Add cards to SSUs and add small APTS units for phase
SSU
PRC
SDHor
SyncE
SyncE
SSU
PRC
SDH
SDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toSyncE
© 2014 ADVA Optical Networking. All rights reserved.18
Evolution example 2a: SDH & PDH → SyncE → G.8275.2
Add cards to SSUs and add small APTS units for phase
SSU
PRC
SDHor
SyncE
SyncE
SSU
PRC
SDH
SDH & PDH
SSU
SyncE
GNSScard
T-GMcard
GNSS
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
) G.8275.2
Add cards
Upgrade toPTP Slave
Upgrade toSyncE
APTS
GNSS
G.8275.2
Add APTS unit
First Aggregation
node
© 2014 ADVA Optical Networking. All rights reserved.19
Evolution example 3a: SDH & PDH → G.8265.1 → G.8275.1
Leverage existing PRC and SSUs, just add cards to SSUs for phase
PRC
SDHor
SyncE
Carrier Ethernet
SSU
PRC
SDH
SDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toPTP Slave
G.8265.1
T-GMcard
Add card
SSU
© 2014 ADVA Optical Networking. All rights reserved.20
Evolution example 3a: SDH & PDH → G.8265.1 → G.8275.1
Leverage existing PRC and SSUs, just add cards to SSUs for phase
PRC
SDHor
SyncE
Carrier Ethernet
SSU
PRC
SDH
SDH & PDH
SSU
CarrierEthernet
GNSScard
T-GMcard
GNSS
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
DeployBoundary Clocks
Add card
UpgradePTP Slave
Upgrade toPTP Slave
Core
G.8265.1
T-GMcard
Add card
SSU
G.8275.1
© 2014 ADVA Optical Networking. All rights reserved.21
Evolution example 4a: SDH & PDH → G.8265.1 → G.8275.2
Add cards to SSUs and add small APTS units for phase
PRC
SDHor
SyncE
Carrier Ethernet
SSU
PRC
SDH
SDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toPTP Slave
T-GMcard
SSU
G.8265.1
Add card
© 2014 ADVA Optical Networking. All rights reserved.22
Evolution example 4a: SDH & PDH → G.8265.1 → G.8275.2
Add cards to SSUs and add small APTS units for phase
PRC
SDHor
SyncE
Carrier Ethernet
SSU
PRC
SDH
SDH & PDH
Phy
sica
l lay
er b
ased
Pac
ket b
ased
(P
TP
)
Upgrade toPTP Slave
T-GMcard
SSU
SSU
CarrierEthernet
GNSScard
T-GMcard
GNSS
G.8275.2
Add card
UpgradePTP Slave
APTS
GNSS
G.8275.2
Add APTS unit
First Aggregation
nodeG.8265.1
Add card
© 2014 ADVA Optical Networking. All rights reserved.23
Conclusions
• Evolution is driven by changes in synchronization needs, network context and synchronization technologies
• There are many possible evolution scenarios
• Leveraging existing SSUs and PRCs is possible with many evolutionscenarios
• Within these scenarios, evolution requires addition on T-GM cardsin SSUs, and possibly addition of small APTS units
• Chosen evolution path has important impact on CAPEX
• Optimal planning of the evolution path is a must
info@advaoptical.com
IMPORTANT NOTICE
ADVA Optical Networking is the exclusive owner or licensee of the content, material, and information in this presentation. Any reproduction, publication or reprint, in whole or in part, is strictly prohibited.
The information in this presentation may not be accurate, complete or up to date, and is provided without warranties or representations of any kind, either express or implied. ADVA Optical Networking shall not be responsible for and disclaims any liability for any loss or damages, including without limitation, direct, indirect, incidental, consequential and special damages, alleged to have been caused by or in connection with using and/or relying on the information contained in this presentation.
Copyright © for the entire content of this presentation: ADVA Optical Networking.
Thank you
schneuwly@oscilloquartz.com
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