دانلود رایگان مقاله انگلیسی زمان انتقال فیبر نوری برای همگام سازی ردیابی UTC برای شبکه های مخابراتی - IEEE 2017

Abstract

A robust and reliable synchronization network, able to distribute signals traceable to a recognized standard, is crucial for the operation of future 5G telecommunication networks. In this article we present the results of time transfer using optical fibers. The main goal is to test the long-term capability of ELSTAB technology (developed by AGH) to deliver time and frequency signals traceable at the sub-nanosecond level to UTC in a real telecommunication environment. In an ongoing cooperation between Deutsche Telekom (DTAG), the Physikalisch-Technische Bundesanstalt (PTB) and AGH University of Science and Technology, we deliver UTC — as realized by PTB in Braunschweig — to a test center of DTAG located in Bremen. For this purpose, a fiber optic link has been operated since July 2015. The results obtained show that the operator of a telecom network may use such a stabilized fiber optic link as a reliable source for synchronization signals with a precision and accuracy superior to those obtained using a state-of-the-art GNSS time receiver. Moreover, a fiber optic link delivering UTC traceable signals increases the robustness and reliability of the network’s synchronization chain by making it less dependent on GNSS.

Summary

In this article we present an idea of extending the synchronization network of future 5G mobile telecom systems by implementing OTT links to obtain traceability to a UTC(k) timescale operated by NMIs and allow real-time monitoring of parameters of PRTC functions in key locations at the network core level. Such an additional supervision level will increase the robustness and reliability of the network’s synchronization chain, making it less dependent on ubiquitous GNSS systems. In some cases it can be considered as an alternative source of synchronization signals of a quality superior to GNSS.

The PoC experiment was performed by sending UTC(PTB) traceable signals via the OTT link from PTB in Braunschweig to the DTAG test center in Bremen using the AGH-developed ELSTAB system. Its results clearly show that the OTT technology fulfills the needs of the telecom operator concerning quality of delivered signals, long-term reliability, scalability, and operation on typical single-mode fibers. Currently, the ITU-T Study Group 15 Question 13 is investigating inclusion of OTT in future ITU-T standards as a means of having the time error under control in a live network.

The operation of the OTT link between PTB and DTAG continues, and the future plans are to change its status from experimental to operational. It is also under consideration to use the same technology to link PTB with the other DTAG timing centers in Germany, in particular with the facility in Frankfurt/Main, where the company’s main timing center is located and UTC(DTAG) is realized today.