We’re empowering service providers to offer GPS/GNSS-backup-as-a-service (GBaaS) as part of their SLAs. Based on our aPNT+™ platform and leveraging a suite of technologies - including multi-band GNSS receivers and AI- and ML-based management software - GBaaS enables end users to address the vulnerabilities of satellite-based and in-network timing. Now there's a simple and flexible way to achieve the highest levels of synchronization resilience and assurance and meet new guidelines and standards for redundant PNT architectures.

1. Introducing GNSS/GPS backup as a service (GBaaS)
A whole new way for service providers to deliver critical timing services with integrated GNSS backup
June 2022

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2
Why synchronization is needed in data centers
• Motivation: Improve data consistency management across distributed data centers
• Tight time synchronization reduces the probability of record inconsistency and reduces
the need to roll back unresolved records
• Common time across distributed data centers is achieved by using GNSS as common
reference + NTP/PTP within the data center
Data center - New York
GNSS
TC/BC
GM
Data center - San Francisco
TC/BC
GM

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3
GNSS vulnerabilities and threats
GNSS for
timing
Jamming and
spoofing
Obstruction
Interference with
transmitters at
adjacent bands
Ionospheric
disturbance, solar
activity
• Feb 2016: GPS error caused satellites to
provide incorrect time information,
impacting operations of several
companies
• Nov 2018: during NATO military
exercises, airspace in Finland was
disturbed by GNSS jamming
• June 2019: Jamming caused
disturbances of operations at Israeli
airport, source unknown
• July 2019: “Ground infrastructure failure”
caused unavailability of Galileo for
several days
• March 2022: GNSS attacks on timing of
Ukrainian critical network infrastructure
Reported GNSS disturbances

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4
Driven by US federal government’s Executive Order 13905 of Feb 2020
• Protect critical government and industry infrastructure against PNT
disruptions from GPS/GNSS jamming/spoofing and other cyberattacks
• Define critical infrastructure under national security threats
• Power grid
• Finance
• Transportation
• Communications (5G, broadcast, defense, etc.)
• Data centers
• Use published resilient PNT guidelines and standard in progress
• DHS Resilient PNT Conformance Framework
• NIST Cybersecurity Framework for PNT Profile
• IEEE P1952 Resilient PNT UE Standard working group
What is the resilient PNT mandate/standard?

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Typical ePRTC implementation
ePRTC G.8272.1 :
Time error +/-30nsec vs UTC (locked)
Time error +/-100nsec vs UTC in 14
days of holdover (30->100ns)
GNSS Cs clock
Combiner
function of ePRTC
ePRC-A G.811.1
Cesium atomic clock
PTP packet master clock
ePRTC combiner + PTP grandmaster

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ePRTC lock and holdover results
Full 65 days run
ePRTC
full lock
3 day
learning
Start
holdover
34 days
holdover
22 days
normal ePRTC operation
GNSS
reconnect
6 days
(normal op’)
TE within +/-20nsec in locked mode
50nsec of phase drift in 34 days of holdover

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ePRTC site resiliency
GNSS
Receiver
Clock
Combiner PPS/PPS+ToD
GNSS antennas
Core redundant grandmaster
10 Mhz
BITS
SyncE
PTP
NTP
Clock
combiner
GNSS
receiver
Carrier-grade
fully redundant
hardware
Multi-band, multi-
constellation
GNSS
PTP+SyncE
Backup from
peer site
Peer core
site
ePRTC with
cesium
backups
Smart antenna
Sync and GNSS
assurance
Advanced
jamming and
spoofing
detection
ePRTC
ePRC cesium
clock
ePRC cesium
clock

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Option 1: Self-provided ePRTC in the data center
Cesium atomic clock
ePRTC combiner + PTP GM
With HW redundancy
TC/BC TC/BC
TC/BC
TC/BC
PTP/NTP
PTP/NTP
PTP/NTP
+/-30nsec
+/-100nsec

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Option 2: GNSS backup as a service (GBaaS)
Core time base network
Single-digit number of
locations, large operator
ePRTC enabled, TE ≤ ±30ns
Aggregation network
Hundreds of locations for large
network
PRTC enabled, TE ≤ ±100ns
Feeders to end application
Thousands of locations for large
network
TE ≤ ± 1100ns
Optical timing
channel (OTC) Optical timing channel
with PTP BC class D
70ns budget
ePRTC
30ns budget
OTC + BC
Data centers
Provider of
GBaaS
- CSP
- Metrology
GBaaS user
- Data center
- Energy
- Finance
- Others

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Aggregation network: time distribution: 9x BC Class D
Test setup: 9x Class D BCs and 370km of fiber (single fiber)
Each BC class D (G.8273.2) adds up to 5nsec of max|TEL|
Single fiber
50 km
Tx: 1615
Rx: 1605
Rx: 1615
Tx: 1605
652.D
Rx: 1615
Tx: 1605
Rx: 1615
Tx: 1605
Rx: 1615
Tx: 1605
Tx: 1615
Rx: 1605
Tx: 1615
Rx: 1605
Tx: 1615
Rx: 1605
A3 A3 A4 A3 A4 A3 A4
50 km
652.D
45 km
652.D
50 km
652.D
45 km
652.D
50 km
652.D
40 km
652.D
40 km
652.D
N1 N2
N2
N1
N2 N1
A2 N1
A4
GNSS
antenna
2 m
Tx: 1615
Rx: 1605
Tx: 1615
Rx: 1605
Rx: 1615
Tx: 1605
Tx: 1615
Rx: 1605
Tx: 1615
Rx: 1605
Rx: 1615
Tx: 1605
Rx: 1615
Tx: 1605
Rx: 1615
Tx: 1605
G8275.1 + SyncE
A3
A1
P2 slave
2 m
P1 master
2 m
SFP/GRAY
SFP/GRAY
SFP/GRAY
High accuracy
Tester
SFP/GRAY
BC_1 BC_2 BC_3 BC_4
BC_5
BC_6
BC_7
BC_8
BC_9

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Aggregation network: time distribution: 9x BC class D
Test results: 9x Class D BCs and 370km of fiber meets ITU-T G.8272 requirements for PRTC-A clock
TE +/-20nsec
MTIE TDEV

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OTC
Aggregation network: timing over ...
Timing over ...
Optimization
methods
Time
error
Layer 3
(Routed)
Small packet size
High
(ms/µs)
Layer 2
(Switched)
VLAN with high
priority
Middle
(µs)
Layer 1
(OTN)
OTN buffer policing
or in-band
transmission
Low
(µs/ns)
Layer 1
(Transparent
WDM)
Single fiber working
Lowest
(ns)
Asymmetry
High
Low

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Optical
line
system
Intermediate
site
Aggregation network: node without OTC
Terminal west Terminal east
Payload traffic
Line terminal
The extract length of each of
the fibers is unknown
The different between length of fibers can be tens of
meters over long-distance connections -> creating
significant asymmetry (~2.5nsec/m)
The in-line amplifiers are
directional and add unknow
delay, which varies between
generations of amplifiers,
types and suppliers

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Optical
line
system
Intermediate
site
Node with OTC
Terminal west Terminal east
PTP over optical timing channel
Payload traffic
Timing device featuring
High-accuracy PTP
boundary clock type D
BiDi transceivers
OTC provides optical budget:
Up to 30dB between two BiDi transceivers
Line terminal

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50KM_a
OSC OSC
OSC OSC OSC
Paragon Neo
OSA BC 5WCA
OTC
Patch-through
Master port Slave port
OSC
OTC accuracy measurment
3GU/1605L
GBE/1615V 3GU/1605L
SFP/GBE/1605V
GBE/1615V GBE/1615V
MALPB-OSC-C MTP-OSC-C MTPB-OSC-C MTPB-OSC-C MTP-OSC-C MTPB-OSC-C
50KM_b 65KM_a 65KM_b
OSA BC
GBE/1310
GBE/1310
210 cm
𝑐𝑇𝐸 ≈
100𝑘𝑚
2
∗ −10𝑛𝑚
18𝑝𝑠
𝑛𝑚 𝑘𝑚
= − 9000𝑝𝑠 = − 9𝑛𝑠 𝑐𝑇𝐸 ≈
130𝑘𝑚
2
∗ −10𝑛𝑚
18𝑝𝑠
𝑛𝑚 𝑘𝑚
= 11700𝑝𝑠 = −11.7𝑛𝑠
|TE| within 15nsec. |cTE| within 5nsec.
Known (fixed)
asymmetry is
configured
on the BC
port

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Summary
• Data centers require stringent phase and time
synchronization
• Accurate synchronization reduce the probability of records
inconsistency and reduces the need to roll back unresolved
records
• “GNSS everywhere” is subject to GNSS vulnerabilities
(jamming, spoofing, etc)
• ePRTC’s can be used to mitigate these risks
• Sub-100nsec accuracy can be delivered from core ePRTC
sites to data center sites using optical timing channel
combined with BC class D
• Now service providers can offer GBaaS, enabling
organizations with strong PNT dependency to access ADVA’s
aPNT+™ protection as a subscription-based service
ePRTC and GBaaS enable robust synchronization in data centers

17. Thank you
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18
GNSS vulnerabilities and threats
GNSS for
timing
Jamming and
spoofing
Obstruction
Interference with
transmitters at
adjacent bands
Ionospheric
disturbance, solar
activity
GNSS segment errors