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Performance of Assisted Partial
Timing Support (APTS)
Dominik Schneuwly, Laurent Gallet
5th November, 2015
© 2015 ADVA Optical Networking. All rights reserved.2
Introduction
Objectives of the tests:
• Study performance potential ...
© 2015 ADVA Optical Networking. All rights reserved.3
Test setup
Network PDV
Emulator
APTS
PTP/
GE
OSA 5548C
TCC-PTP v2
OS...
© 2015 ADVA Optical Networking. All rights reserved.4
Test sequence
GM
GNSS
ON
OFF
Phase 1 Phase 2 Phase 3
APTS
Locked to:...
© 2015 ADVA Optical Networking. All rights reserved.5
Two APTS mechanisms
1. Normal condition: locked to GNSS
Simultaneous...
© 2015 ADVA Optical Networking. All rights reserved.6
Three PDV impairment cases
1. A static delay asymmetry between forwa...
© 2015 ADVA Optical Networking. All rights reserved.7
Summary of test cases
Test # APTS mode PDV impairment profile
1 Lock...
© 2015 ADVA Optical Networking. All rights reserved.8
Measurements
What is being measured?
• Time Error TE of the outgoing...
© 2015 ADVA Optical Networking. All rights reserved.9
Discussion
• Are the PDV traces emulating G.8261/VI test cases the r...
© 2015 ADVA Optical Networking. All rights reserved.10
Test #1, Time Error
Static asymmetry of 10 µs, APTS = phase lock & ...
© 2015 ADVA Optical Networking. All rights reserved.11
Test #1, Time Error
Static asymmetry of 10 µs, APTS = phase lock & ...
© 2015 ADVA Optical Networking. All rights reserved.12
Test #1, MTIE (dynamic Time Error)
0.1 1 10 100 1,000 10,000
τ [s]
...
© 2015 ADVA Optical Networking. All rights reserved.13
Test #2, Time Error
G.8261/VI test case 12-1, APTS = phase lock & a...
© 2015 ADVA Optical Networking. All rights reserved.14
Test #2, MTIE (dynamic Time Error)
0.10.01 1 10 100 1,000 10,000
τ ...
© 2015 ADVA Optical Networking. All rights reserved.15
Test #3, Time Error
G.8261/VI test case 13-1, APTS = phase lock & a...
© 2015 ADVA Optical Networking. All rights reserved.16
Test #3, MTIE (dynamic Time Error)
0.10.01 1 10 100 1,000 10,000
τ ...
© 2015 ADVA Optical Networking. All rights reserved.17
Test #4, Time Error
Static asymmetry of 10 µs, APTS = frequency loc...
© 2015 ADVA Optical Networking. All rights reserved.18
Test #4, Time Error
Static asymmetry of 10 µs, APTS = frequency loc...
© 2015 ADVA Optical Networking. All rights reserved.19
Test #4, MTIE (dynamic Time Error)
0.1 1 10 100 1,000 10,000
τ [s]
...
© 2015 ADVA Optical Networking. All rights reserved.20
Test #5, Time Error
G.8261/VI test case 12-1, APTS = frequency lock...
© 2015 ADVA Optical Networking. All rights reserved.21
Test #5, MTIE (dynamic Time Error)
G.8261/VI test case 12-1, APTS =...
© 2015 ADVA Optical Networking. All rights reserved.22
Test #6, Time Error
G.8261/VI test case 13-1, APTS = frequency lock...
© 2015 ADVA Optical Networking. All rights reserved.23
Test #6, MTIE (dynamic Time Error)
0.10.01 1 10 100 1,000 10,000
τ ...
© 2015 ADVA Optical Networking. All rights reserved.24
Compared with holdover …
• Holdover (XO & Rb), ideal conditions (te...
© 2015 ADVA Optical Networking. All rights reserved.25
Summary
APTS
GNSS
PRTC
/GM
GNSS
Node B
eNB
356 ns
Test #1
Test #2
T...
© 2015 ADVA Optical Networking. All rights reserved.26
Conclusion
• Tests based on G.8261 test cases (!) show that the max...
Thank You
IMPORTANT NOTICE
The information in this presentation may not be accurate, complete or up to date, and is provid...
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Performance of Assisted Partial Timing Support (APTS)

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Dominik Schneuwly and Laurent Gallet explore performance of assisted partial timing support (APTS) in their ITSF 2015 presentation

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Performance of Assisted Partial Timing Support (APTS)

  1. 1. Performance of Assisted Partial Timing Support (APTS) Dominik Schneuwly, Laurent Gallet 5th November, 2015
  2. 2. © 2015 ADVA Optical Networking. All rights reserved.2 Introduction Objectives of the tests: • Study performance potential of APTS • Compare several ways of locking to the back-up GM • Draw conclusions for the architecture Method • Emulate PDV of the network • Measure TE at output of the APTS Clock before and after protection event (GNSS failure)
  3. 3. © 2015 ADVA Optical Networking. All rights reserved.3 Test setup Network PDV Emulator APTS PTP/ GE OSA 5548C TCC-PTP v2 OSA 5410Paragon GNSS GNSS PTP/ GE PTP/ GEPRTC /GM Measurement instrument Paragon-X Disconnectable Reference, 1PPS 1PPS
  4. 4. © 2015 ADVA Optical Networking. All rights reserved.4 Test sequence GM GNSS ON OFF Phase 1 Phase 2 Phase 3 APTS Locked to: PDV Impairment t
  5. 5. © 2015 ADVA Optical Networking. All rights reserved.5 Two APTS mechanisms 1. Normal condition: locked to GNSS Simultaneously: slave port time-locked to Core GM and measurement of delay asymmetry Failure condition: time-lock to Core GM and delay asymmetry compensation 2. Normal condition: locked to GNSS Simultaneously: slave port frequency-locked to Core GM Failure condition: frequency-lock to Core GM; time clock continues ticking with this frequency Time scale Frequency lock Counter PTP master engine PTP flow Time scale Time scale Time lock Asymm. comp. PTP flow PTP master engine PTP flow
  6. 6. © 2015 ADVA Optical Networking. All rights reserved.6 Three PDV impairment cases 1. A static delay asymmetry between forward and reverse directions of 10 µs 2. G.8261/VI test case 12, traffic model 11: 80% traffic load in forward direction over 10 nodes 20% traffic load in reverse direction over 10 nodes 3. G.8261/VI test case 13, traffic model 11: Sudden load changes Black: forward direction (10 nodes) Red: reverse direction (10 nodes) Note 1: using Calnex reference PDV traces
  7. 7. © 2015 ADVA Optical Networking. All rights reserved.7 Summary of test cases Test # APTS mode PDV impairment profile 1 Lock time via PTP transfer, asymmetry compensation 10 µs static delay asymmetry 2 Idem G.8261/VI test case 12, traffic model 11 3 Idem G.8261/VI test case 13, traffic model 11 5 Hold time via PTP frequency transfer 10 µs static delay asymmetry 6 Idem G.8261/VI test case 12, traffic model 11 7 Idem G.8261/VI test case 13, traffic model 11
  8. 8. © 2015 ADVA Optical Networking. All rights reserved.8 Measurements What is being measured? • Time Error TE of the outgoing two-way PTP stream, i.e. avg(TET1, TET4) What is being calculated? • max │TE│, MTIE What are the results compared against? • Network Limits @ reference point C, G.8271.1, Amd1, § 7.3
  9. 9. © 2015 ADVA Optical Networking. All rights reserved.9 Discussion • Are the PDV traces emulating G.8261/VI test cases the right ones for evaluating APTS? • Questionable, because G.8261/VI is for a network without timing support from the network; consequence: the test is actually too tough on the tested APTS function • Are the Network Limits of G.8271.1 the right ones for evaluating APTS? • No (formally), because G.8271.1 is for the case of full timing support from the network; G.8271.2 will specifiy network limits for the case of partial timing support, both assited and non-assisted; but it is not yet finalized. • Yes, because: why should the network limit at reference point C be any different in the case of assisted partial timing support? Note 1: Calnex bi-directional reference PDV traces
  10. 10. © 2015 ADVA Optical Networking. All rights reserved.10 Test #1, Time Error Static asymmetry of 10 µs, APTS = phase lock & asymmetry compensation max│TE│= 38 ns ≤ 1100 ns
  11. 11. © 2015 ADVA Optical Networking. All rights reserved.11 Test #1, Time Error Static asymmetry of 10 µs, APTS = phase lock & asymmetry compensation max│TE│= 38 ns ≤ 1100 ns
  12. 12. © 2015 ADVA Optical Networking. All rights reserved.12 Test #1, MTIE (dynamic Time Error) 0.1 1 10 100 1,000 10,000 τ [s] MTIE [ns] Network Limit G.8271.1 100 10 1,000 1 Static asymmetry of 10 µs, APTS = phase lock & asymmetry compensation
  13. 13. © 2015 ADVA Optical Networking. All rights reserved.13 Test #2, Time Error G.8261/VI test case 12-1, APTS = phase lock & asymmetry compensation max│TE│=116 ns ≤ 1100 ns
  14. 14. © 2015 ADVA Optical Networking. All rights reserved.14 Test #2, MTIE (dynamic Time Error) 0.10.01 1 10 100 1,000 10,000 τ [s] MTIE [ns] Network Limit G.8271.1 100 10 1,000 1 G.8261/VI test case 12-1, APTS = phase lock & asymmetry compensation
  15. 15. © 2015 ADVA Optical Networking. All rights reserved.15 Test #3, Time Error G.8261/VI test case 13-1, APTS = phase lock & asymmetry compensation max│TE│= 210 ns ≤ 1100 ns
  16. 16. © 2015 ADVA Optical Networking. All rights reserved.16 Test #3, MTIE (dynamic Time Error) 0.10.01 1 10 100 1,000 10,000 τ [s] MTIE [ns] Network Limit G.8271.1 251 158 398 631 G.8261/VI test case 13-1, APTS = phase lock & asymmetry compensation
  17. 17. © 2015 ADVA Optical Networking. All rights reserved.17 Test #4, Time Error Static asymmetry of 10 µs, APTS = frequency lock max│TE│= 36 ns ≤ 1100 ns
  18. 18. © 2015 ADVA Optical Networking. All rights reserved.18 Test #4, Time Error Static asymmetry of 10 µs, APTS = frequency lock max│TE│= 36 ns ≤ 1100 ns
  19. 19. © 2015 ADVA Optical Networking. All rights reserved.19 Test #4, MTIE (dynamic Time Error) 0.1 1 10 100 1,000 10,000 τ [s] MTIE [ns] Network Limit G.8271.1 100 10 1,000 1 Static asymmetry of 10 µs, APTS = frequency lock
  20. 20. © 2015 ADVA Optical Networking. All rights reserved.20 Test #5, Time Error G.8261/VI test case 12-1, APTS = frequency lock max│TE│= 410 ns ≤ 1100 ns
  21. 21. © 2015 ADVA Optical Networking. All rights reserved.21 Test #5, MTIE (dynamic Time Error) G.8261/VI test case 12-1, APTS = frequency lock
  22. 22. © 2015 ADVA Optical Networking. All rights reserved.22 Test #6, Time Error G.8261/VI test case 13-1, APTS = frequency lock max│TE│=356 ns ≤ 1100 ns
  23. 23. © 2015 ADVA Optical Networking. All rights reserved.23 Test #6, MTIE (dynamic Time Error) 0.10.01 1 10 100 1,000 10,000 τ [s] MTIE [ns] Network Limit G.8271.1 100 10 1,000 1 G.8261/VI test case 13-1, APTS = frequency lock
  24. 24. © 2015 ADVA Optical Networking. All rights reserved.24 Compared with holdover … • Holdover (XO & Rb), ideal conditions (temperature, initial offsets):
  25. 25. © 2015 ADVA Optical Networking. All rights reserved.25 Summary APTS GNSS PRTC /GM GNSS Node B eNB 356 ns Test #1 Test #2 Test #3 Test #4 Test #5 Test #6 Frequencylock Phaselock& asymmetry compensation max│TE│
  26. 26. © 2015 ADVA Optical Networking. All rights reserved.26 Conclusion • Tests based on G.8261 test cases (!) show that the max│TE│ at the output of the APTS Clock is well below the 1.1 µs in the GNSS failure case. • The test results suggest that the APTS Clock can be placed in the first aggregation site. • With the PDV emulations used, phase lock with asymmetry compensation fares somewhat better than frequency lock, but this probably depends on the test and network conditions. • The results depend on the algorithms used in the APTS Clock. • APTS is better than quartz-based holdover. APTS GNSS PRTC /GM GNSS Node B eNB Aggregation Network First Aggregation Site Access Network
  27. 27. Thank You IMPORTANT NOTICE 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.

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