White Rabbit Precision Time Protocol on Long-Distance Fiber Links.

Area of Science:

• Networking and Telecommunications
• Precision Time Transfer
• Optical Fiber Systems

Background:

• White Rabbit Precision Time Protocol (WR-PTP) is designed for synchronizing equipment in synchronous Ethernet networks, typically within 10 km.
• Existing communication fiber networks offer potential infrastructure for extending WR-PTP capabilities.

Purpose of the Study:

• Investigate the application and limitations of WR-PTP in long-distance optical fiber links.
• Evaluate WR-PTP performance in real-world communication networks beyond its original intended range.

Main Methods:

• Implemented WR-PTP over a 950-km unidirectional fiber link (Espoo-Kajaani, Finland) and compared it with GPS Precise Point Positioning (PPP).
• Implemented WR-PTP over two cascaded 137-km bidirectional fiber links (Delft-Amsterdam, Netherlands).
• Analyzed time transfer accuracy and identified sources of uncertainty, such as chromatic dispersion.

Main Results:

• The 950-km WR-PTP link showed agreement within [Formula: see text] compared to GPS PPP over three months.
• The 274-km cascaded link achieved a time offset within 5 ns with 8 ns uncertainty.
• Chromatic dispersion was identified as a primary factor contributing to delay asymmetry and uncertainty in bidirectional links.

Conclusions:

• WR-PTP can be successfully applied to long-distance optical fiber links, significantly extending its operational range.
• The protocol demonstrates high accuracy and stability for time transfer over extended fiber networks.
• Further research is needed to mitigate dispersion effects for enhanced performance in bidirectional fiber links.