Synchronization system with symmetric optical fiber links

In most synchronization schemes based on fiber, the compensation on fiber link asymmetry significantly affects the synchronization accuracy, thus complicated calibration may be needed to achieve high performance synchronization. Moreover, as the fiber temperature varies, fiber link asymmetry is not fixed, leading to synchronization deterioration, especially in long distance applications. This paper proposes a new synchronization scheme named LBSYNC, which achieves complete symmetry fiber link with new loopback structure. LBSYNC is based on White Rabbit system, a high performance synchronization technology with sub-nanosecond accuracy and tens of picoseconds precision, but adopts customized protocol. Theoretical analysis and experiments show that LBSYNC can achieve better synchronization performance than White Rabbit system in the fiber interconnection situation or the fiber temperature fluctuation situation, which is expected to have wider applicability in actual deployment environment.