Precise Time Distribution and Synchronization for Low Latency Slotted Optical Metro-Access Networks

Future optical metro access networks will connect heterogeneous access technologies like beyond 5G radio access networks and edge computing interconnections. These access networks and their diversified use cases will impose significant challenges on network capacity, wavelength resource and network synchronization. In this paper, we present and investigate a novel time slotted optical metro access network controlled by a multifunctional supervisory channel for precise time distribution, nodes synchronization, and fast wavelength reusing to improve the overall network performance for low and deterministic latency applications. The supervisory channel carries timestamps of different nodes in different time slots, and the labels with the data channels destinations in every time slot. By analyzing the supervisory channel at each node, the timestamps and add/drop information can be precisely and fast exchanged. A network testbed has been implemented for assessing the proposed network operation and precise time synchronization. The results show successful time slotted network operation, 82% of bandwidth usage and 2.5 s latency have been achieved. Below 12 ns time accuracy has been measured for a metro ring and 5G front haul network with a single time reference. To assess the scalability and wavelength saving of the proposed network in a larger network, a simulation model has been developed in OMNeT++ based on the experimental parameters. Numerical results show more than 16 % wavelengths can be saved by our technology compared with Cloud Burst Optical-Slot Switching (CBOSS)[1].