White rabbit: a PTP application for robust sub-nanosecond synchronization

Abstract

This article describes time distribution in a White Rabbit Network. We start by presenting a short overview of the White Rabbit project explaining its requirements to highlight the importance of the timing aspects of the system. We then introduce the technologies used to achieve high clock accuracy, stability and resilience in all the components of the network. In particular, the choice of the IEEE 1588-2008 (PTP) and Synchronous Ethernet standards are explained. In order to accommodate hardwaresupported mechanisms to increase PTP synchronization accuracy, we introduce the White Rabbit extension to PTP (WRPTP). The hardware used to support WRPTP is presented. Measured results of WRPTP performance demonstrate sub-nanosecond accuracy over a 5km fiber optic link with a precision below 10ps and a reduced PTP-message exchange rate. Tests of the implementation show full compatibility with existing PTP gear.

Time-fluctuation error influence on downlink CoMP performance in mobile fronthaul

“…In actual communication, time fluctuation, frequency error, and MIMO channel variation occur at the same time, and so the requirements for the wireless total characteristics can be divided into the above three factors. These results show that the existing layer 2 network (L2NW) time synchronization technologies such as PTP and White Rabbit [7], which achieve integrated jitter below 2.5 ps, can be applied and seem to suggest that the CoMP coherent JT sufficiently works even in a MFH with a L2NW.…”

A Survey of Clock Synchronization Over Packet-Switched Networks

“…White Rabbit (WR) is a synchronization technology combining the PTP and SyncE standards in order to meet subnanosecond accuracy requirements for particle accelerators and cosmic particle detectors [73]- [75]. These applications require deterministic and reliable data delivery as well as subnanosecond synchronization accuracy.…”

High‐Speed Deterministic‐Latency Serial IO

“…The timing offset between the clocks grows linearly with the delay difference. Minimizing this difference, also by achieving deterministic-latency transmission at each system reset, allows the system to improve the accuracy of the synchronization [3].…”