High accuracy timing and synchronisation for a telecom Infrastructure

Rajagopal, Lakshmi (2025). High accuracy timing and synchronisation for a telecom Infrastructure. University of Birmingham. Ph.D.

Rajagopal2025PhD.pdf
Text - Accepted Version
Available under License All rights reserved.
Download (9MB)

Abstract

The scientific community is performing groundbreaking experiments to develop the best clocks in the world. Recently, strontium-based optical lattice clocks have been reported to provide stability and precision to 10^(-18) levels. In addition to that, the research community has been developing compact transportable optical lattice clocks, with the aim of bringing them out of research labs to real network environments. These clocks might be an alternative solution to satellite technologies in the near future for positioning, navigation and timing services. They are capable of providing timing and synchronisation to sub-nanosecond or picosecond levels in future networks through terrestrial networks. However, there is a lot more to investigate regarding challenges incurred while disseminating the clock output across the fibre networks. These challenges can be the factors affecting frequency and phase stability, network configuration, long-term stability and accuracy and much more.

At present, the telecommunication infrastructure relies on microwave-based atomic clocks and satellite-based technologies for accurate phase, frequency and time of day at the network core. Optical atomic clocks are the next generation of atomic clocks capable of replacing microwave-based atomic clocks and satellite-based technologies at the network core in the coming years. The research work delves into the practical applications of optical lattice clocks in telecommunication networks, particularly in disseminating time and frequency at a national scale. This report outlines the initial steps towards this goal, which includes the development of a time dissemination simulation platform at a national scale with subnanosecond level timing accuracy, with optical atomic clocks at the core nodes of telecom infrastructure. The simulation model investigates various novel architectures to identify the best possible way to connect optical atomic clocks to a telecom infrastructure in future. The research also explores the use of FPGAs to synchronise multiple nodes to picosecond scale precision. The implementation of a time-to-digital converter module on an FPGA along with the novel technique for offset calibration aids to synchronise multiple nodes to picosecond scale precision. The need for high-accuracy clocks and improved transport schemes is crucial to transport high-accuracy timing from the core to the access node in a telecom infrastructure. The PhD work focuses on the intricacies of transporting timing signals within sub-nanosecond or picosecond timescales in telecom infrastructure, highlighting the practical implications of this research.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):