Agenda

MSc SS Thesis Presentation

• Monday, 6 September 2021
• 14:30-15:15

Time Synchronization for Anchorless Satellite Networks

In this thesis, we propose a new class of pairwise frequency and multi-domain time synchronization and ranging algorithms and in a case study address network and mission level aspects of time synchronization on the example of the Orbiting Low Frequency Array for Radio astronomy (OLFAR), a proposed distributed radio interferometer.

The new class of frequency and multi-domain time synchronization and ranging algorithms proposed is applicable to anchorless mobile networks of asynchronous nodes. In a first step, the Frequency Pairwise Least Squares (FPLS) that estimates clock skew and relative velocity in a pairwise setup using only frequency measurements is formulated. In a second step, we extend this method to a motion model with constant acceleration. As frequency domain methods do not estimate clock offset and pairwise range, relying purely on frequency domain estimates is not feasible for most applications.

To harness the potential of frequency domain synchronization and ranging, the Combined Pairwise Least Squares (CPLS) has been developed. The combined method reduces the number of minimum required messages from 4 to 3 compared to current methods and decreases the computational complexity. Using a generic simulation with nodes in pairwise non-linear motion, we show that frequency domain methods can outperform time domain methods in clock skew and relative velocity estimation and that the proposed multi-domain method delivers better clock offset and pairwise range estimation in low to medium SNR conditions.

In the second part of our work, we apply the novel methods to OLFAR –— a spaceborne large aperture radio interferometric array platform. We address network level and mission level aspects, proposing network path planning for pairwise synchronization algorithms and determining the required resynchronization period. i

Overview of MSc SS Thesis Presentation