Status and challenges for practical implementation
of synchronization in a NGN network seen from a
Telecom Operator’s perspective
Sverre Bjønnes, Telenor Norway
Contents
1. Implementation of SyncE in the Telenor Core network in Norway for frequency
synchronisation.
2. Status for implementation of 1588v2 for frequency synchronisation
3. Challenges for an existing operators network when phase-synchronization is
introduced for LTE-A/LTE-TDD
2
Implementation of SyncE in the
Norwegian Core network for frequency
synchronisation.
• NEs used in SDH-Core are
the oldest SDH-NEs and
should be replaced (>15y)
• Old STM-16 SDH-rings
which is carrying sync are
nearly emptied.
4
From sync
distribution in SDH CORE
5
PRC
R11
CC11
R12
R2m
CC12 CC13
R22 R21
CC21
R3o
CC22 CC23 CC2n
R3m R3m R3m SEC (G.813)
SEC (G.813)
SSU (G.812)
PRC (G.811)
Will be removed first
Will be removed later
Cross Connect w/ G.812
SDH ring
SSU (G.812)
SEC (G.813)
• NEs used in SDH-Core are
the oldest SDH-NEs and
should be replaced (>15y)
• Old STM-16 SDH-rings
which is carrying sync are
nearly emptied.
• Traffic are moved to IP over
WDM.
• IP network are chosen as
carrier for synchronisation
6
From sync
distribution in SDH CORE
To SyncE
distribution in Telenor MPLS and IP/VPN CORE
network
Implementation of SyncE in the
Norwegian Core network for frequency
synchronisation.
• Test to be executed with SyncE from PRC in Oslo to IP nodes with GPS
reference in Tromsø (1966 km fibre + 14% delay due to DCMs).
• SASE (G.812 clocks) to be used between SyncE distribution in Core
and sync input via SDXC to the regional SDH network
7
SyncE distribution in Telenor MPLS and IP/VPN CORE network
Sync distribution from IP Core Network to SDH regional network
Mobile network with IEEE-1588v2 sync distribution -
frequency.
• Green: 6 hops minimum + MPLS-core
• Red (Fault situation): 11 hops maximum + MPLS-core
9
MSS
MSS
MSS MSS
MSS
MSS
BNG
BNG
MPLS/IP
Network BNG RSS
IPClk / GM
CSS CSS Node B/OC Node B/OC
Metro-ring (MPLS/IP)
MSS – Metro Site Switch
Supports TC and BC
CSS – Cell Site Switch
BNG - Broadband Network Gateway
Supports SyncE
RSS - RNC Site Switch
(RNC = Radio Network Controller)
10
Challenges for an existing operators network when
phase-synchronization is introduced
for LTE-A / LTE-TDD
Mobil network
with IEEE-
1588v2
Green: 2-fiber WDM system
Red: 1-fiber CWDM system or BiDi SFP
Blue: Micro-wave system (No adaptive modulation used)
11
MSS
MSS
MSS MSS
MSS
MSS
BNG
BNG
MPLS/IP
Network BNG RSS
IPClk / GM
CSS
CSS
Node B Node B
Metro-ring (MPLS/IP)
(up to ~600 km)
x
Node B
Node B
CSS
CSS
CWDM
CWDM
CWDM
MSS
Mobil network
with IEEE-1588v2
for phase-
synchronisation
• Introduction of BC with SyncE support will:
• Reduce the number of clients to be connected towards GM
• Reduce the number of hops from Node B to nearest master
• Crypto between Node B and BNG. PTP packets not available between Node
B and BNG. TC/BC in MSS not available!
• Layer 3 and preferably also multicast have to be activated to use TC/BC in
Metro-ring
12
MSS MSS
MSS MSS
BNG
BNG
MPLS/I
P
SyncE BNG RSS
IPClk / GM
CSS
CSS Node B Node B
Metro-ring (MPLS/IP)
(up to ~600 km)
Node B
Node B
CSS
CSS
BC
BC MSS
Requirements for adjacent clusters using different parts of the transport network
providing timing for LTE-A with or without CoMP (coordinated multipoint)
13
MPLS/IP
SyncE BNG RSS
IPClk / GM
MSS
MSS
MSS MSS
MSS
MSS
BNG
BNG
CSS CSS
Node B Node B
Metro-ring 1 (MPLS/IP)
x
Node B
Node B
CSS
CSS
CWDM
CWDM
CWDM
MSS
MSS
BNG
Metro-ring 2 (MPLS-IP) CWDM
MSS
BNG
MSS
Node B
Node B
CSS
CSS
?
? ? ?
?
BC
BC
BC
BC
Core Network
operator serving
multiple
Mobile Operators
• Mobile operator owns GM and provides timing for his own purpose
• Requirements for the Core Network
• BC at BNG will have support for SyncE
• TC at Metro-Ring is desirable, but will have problems due to Crypto and MPLS 14
MSS
MSS
MSS MSS
MSS
MSS
BNG
BNG
MPLS/IP
SyncE BNG
RSS Operator 1
IPClk / GM
CSS
Node B2
Metro-ring (MPLS/IP)
CSS
RSS Operator 2
Node B1 Node B2 Node B1
BC
BC IPClk / GM
BC
BC
Core Network
operator serving
multiple
Mobile Operators
• Network operator owns GM and provides timing
15
MSS
MSS
MSS MSS
MSS
MSS
BNG
BNG
MPLS/IP
SyncE BNG
RSS Operator 1
IPClk / GM
CSS
Node B2
Metro-ring (MPLS/IP)
CSS
RSS Operator 2
Node B1 Node B2 Node B1
BC
BC
Summary
• This presentation is made in order to point out challenges for an operator to
support phase-synchronization.
• New infrastructure just installed for IP/MPLS Core and IP mobile backhaul.
Short term solutions should be based on existing hardware!
• LTE-A, LTE-TDD and LTE-A CoMP
Which phase-requirements will be relevant for the Network to serve different
sizes of radio sub-networks?
• Implementation of TC and BC in MPLS-networks is a challenge
• CRYPTO when used is a challenge as traffic- and sync-packets use the same
VPN between Node B and a «CRYPTO-Box»
16