White Rabbit–Enabled Deterministic Triggering for Bi-Static ISAC in 6G
Year: 2026
Type: conference-paper
Abstract: Distributed beyond-5G/6G integrated sensing and communication (ISAC) platforms require sub-nanosecond synchronization of time, frequency, and phase across spatially separated nodes to preserve beamforming gain and sensing fidelity. Conventional coaxial clock and trigger fan-outs achieve excellent stability but are limited to rack-scale distances, typically on the order of meters, motivating fiber-based transfer when nodes must be placed further apart.We present a lightweight trigger layer that uses White Rabbit (WR)—combining PTP hardware timestamping, SyncE frequency transfer, and digital dual-mixer time difference (DDMTD) phase metrology—to provide a shared reference over fiber. Each FPGA endpoint schedules and emits triggers locally based on a master-announced timestamp referenced to International Atomic Time (TAI), decoupling fidelity from fiber length while allowing timing and payload data to coexist on the same link.In a two-node fiber setup, 3774 trigger pairs were recorded. After conservative gross-outlier rejection using |z| < 2.7, 3758 pairs remained and yielded a median inter-node skew of 7.681 ns, 12.21 ps RMS jitter, and 66.04 ps peak-to-peak spread. Compared to coax fan-outs, which achieve approximately 2.09 ps stability, our approach trades short-term precision for longer-range synchronization, enabling coherent ISAC operation across spatially separated nodes.
Language: English
Subfield: Computer Networks and Communications
Field: Computer Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7224887291