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Improving time accuracy at the network edge


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At WSTS 2018, Ken Hann discussed the latest synchronization technology enabling PRTC timing accuracy indoors and in deep urban canyons.

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Improving time accuracy at the network edge

  1. 1. WSTS 2018 Kenneth Hann WSTS 2018 UTC Improving time accuracy at the network edge
  2. 2. © 2018 ADVA Optical Networking22 Motivation and background New technologies require high levels of time accuracy • eICIC, TDD, 5G, small-cell, ... Synchronization over network is challenging … • Legacy networks • Diversity of standards • Multi-vendor/operator networks High accuracy; GNSS based solution; low in network • Accuracy • Verification • Results
  3. 3. © 2018 ADVA Optical Networking33 IoT PRTC - Solution overview High accuracy; GNSS-based solution; low in network IoT PRTC requirements • Simple installation • Indoor or outdoor • No calibration/compensation • “UTC out-of-the-box” • Protection via network UTC
  4. 4. © 2018 ADVA Optical Networking44 GNSS satellites Direct signal Reflected signal OVP + (line amp) PRTC PTP network • Antenna delay • RF line amplifier delay • RF cable(s) delay • RF splitter delay • Multi-path effects Fixed delays Compensate fixed delays for high time accuracy PRTC time error with traditional system
  5. 5. © 2018 ADVA Optical Networking55 Time variation + offset (or ACDC) UTC LeadingUTCTE(ns) Major sources of time offset: 1) Cable delays 2) Multipath 14ns (Variation) 62ns (Offset)
  6. 6. © 2018 ADVA Optical Networking66 Accurate compensation of RF delays is difficult PRTC accuracy = sum of many ”system” parts OVP + (line amp) PRTC Typical delay (type) Exact delay (unit) Antenna 30ns 34ns Line amplifier 10ns 12ns Cables 210m (840ns) 215m (887ns) Splitter 15ns 5ns Total 895ns 938ns 34ns 12ns 918ns 5ns
  7. 7. © 2018 ADVA Optical Networking77 Sources of time error with IoT PRTC GNSS satellites Antenna delay RF Line Amplifier delay RF cable(s) delay RF splitter delay Multi-path effects Direct signal Reflected signal PRTC PTP network IoT PRTC removes cable delay etc. Algorithms reduce multi-path delays Fixed Delays
  8. 8. © 2018 ADVA Optical Networking88 OVP + (line amp) PRTC PRTC Outdoors Indoors UTC Evolution of PRTC to IoT PRTC
  9. 9. © 2018 ADVA Optical Networking99 IoT PRTC = Ease of installation + low cost • Integrated GNSS antenna with PTP grandmaster • Standard Ethernet/IP connectivity • Installation - indoor or simple outdoor locations • No delay compensation required • Copper or fiber connection (reach + lightning immunity) Outdoor Indoor
  10. 10. © 2018 ADVA Optical Networking1010 Mounting options for urban canyons Location choice Indoor - window Outdoor - pole/wall/roof
  11. 11. © 2018 ADVA Optical Networking1111 Indoor Small Cell Sync Requirements • GM with integrated GNSS antenna • optional external antenna • PTP capacity for building (~64) • Cost-effective and compact design • Window installation • Ethernet cabling: • Copper/POE • Fiber • Multiple protection options: • Sync-E • PTP • APTS • Supports multiple profiles
  12. 12. © 2018 ADVA Optical Networking1212 Outdoor small cell sync requirement • Features as indoor plus … • Options to be installed on: • External walls, • Pole / lamp post, • Roof • Rugged device • -40C to +65C • IP66 waterproof GNSS/PRTC/PTP GM Pole mount Street cabinet top External wall mount
  13. 13. © 2018 ADVA Optical Networking1313 From VTT Finnish timekeeper Measurement results
  14. 14. © 2018 ADVA Optical Networking1414 Time from Finnish timekeeper VTT MIKES Testing UTC – needs good UTC reference • VTT provides UTC MIKES • Distance 876m • Fibre connection • PTP White Rabbit • Accuracy UTC ~5ns
  15. 15. © 2018 ADVA Optical Networking1515 Antenna/GM testing locations at VTT #1 Indoor (glass bricks); #2 Outdoor (wall) #1 Indoor #2 Outdoor
  16. 16. © 2018 ADVA Optical Networking1616 VTT Test results (~1 week) 5405 OutdoorTimeerror(ns)toUTCMikes TIE 35nsec Offset 10nsec (lagging UTC) Modified Julian Day
  17. 17. © 2018 ADVA Optical Networking1717 VTT Test results (~1 week) 5405 IndoorTimeError(ns)toUTCMIKES TIE 40ns Offset 15ns (ahead of UTC) Modified Julian Day
  18. 18. © 2018 ADVA Optical Networking1818 VTT Test results – MTIE/TDEV
  19. 19. © 2018 ADVA Optical Networking1919 IoT PRTC – suitable for ultra-high accuracy (Per-unit compensation is possible) Typical (type) Exact (unit) Time offset 0ns 4ns Time variation* +/-3ns +/-3ns 4ns +/- 3ns PRTC Extremely low fixed time offset Time offset stable across e.g. link flaps “Precise UTC out-of-box” * Depends on installation location and GNSS constallations used
  20. 20. © 2018 ADVA Optical Networking2020 “Precise UTC out-of-box” IoT PRTC – suitable for For ultra high accuracy (Per-unit compensation is possible) Typical (type) Exact (unit) Time offset 0ns 4ns Time variation* +/-3ns +/-3ns 4ns +/- 3ns PRTC * Depends on installation location and GNSS constallations used Extremely low fixed time offset Time offset stable across link flaps; resets; etc.
  21. 21. © 2018 ADVA Optical Networking2121 Conclusions - IoT PRTC Easier-to-install and lower-cost solution PRTC accuracy indoors and in deep urban canyons (multi-path delay reduction) Also platform for high accuracy UTC
  22. 22. © 2018 ADVA Optical Networking2222 Thank You
  23. 23. Thank you IMPORTANT NOTICE The content of this presentation is strictly confidential. 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.