(百度翻譯)

5G的時間：增強PRTC的重要作用

當今快速發展的行動網路和回程技術使得蜂窩站點同步成為前所未有的挑戰。4.5G和5G應用需要新的頻率和相位精度水平。

在電信之外，計時技術現在同樣重要。從資料中心的互聯性到重要的政府防禦網絡，在所有行業中，非常精確的同步是必不可少的。我們的關鍵國家基礎設施，如能源和水供應、醫療保健和運輸，取決於快速故障定位的精確時機和分散式控制過程的有效執行。金融交易服務依賴於可信和精確的時間戳。對於支援所有領域科學家工作的計量學，也需要高度準確和穩定的網路同步。

挑戰不僅僅是傳遞更高的準確度。非凡的健壯性和可靠性現在也是必不可少的。隨著全球導航衛星系統脆弱性的危險日益增加，由於蓄意欺騙和干擾攻擊或太陽耀斑和空間天氣事件的自然威脅，提供所需的可用性水平是一項艱鉅的任務。依賴於基於GNSS的同步的解決方案不再足以滿足基礎設施關鍵任務的需要。確保備份現在是實現安全同步的必經步驟。

增強時序

由ITU-T G8272.1建議所定義，增強型主參考時鐘(ePRTC)系統將可靠性和準確性提高到下一水平。ePRTC同步源可以滿足下一代行動網路的要求，提供當今工業所需的精確同步，並消除GNSS中斷的脆弱性。使用ePRTC，保持精確的定時至少14天。它也產生了比標準PRTCs更高的精度水平。雖然PRTC的時間輸出應該精確到UTC的100ns以內，但這新一代的定時源將時間交付到僅僅30ns以內。ePRTC規範提供了一個新水平的穩定性、準確性和可靠性。

ePRTC系統的關鍵在於，它們使用高效能銫時鐘結合UTC可跟蹤基準（例如GNSS接收機）來構造自己的時間。這有助於濾除大氣干擾、太陽風暴或電離層變化對從全球導航衛星系統恢復的定時的影響所引起的波動。這種基於GNSS的系統與銫頻率標準的創新組合利用了兩種定時方法的優點，並極大地提高了頻率、相位和時間同步的精度。

保持能力的量子躍進

這就是為什麼我們建立了OSA ePRTC系統——高度精確和自主的定時解決方案，使運營商能夠為其現有基礎設施帶來長期的精度。使用我們的ePRTC升級您的系統，在不增加大量成本和複雜性的情況下，顯著地提高了準確性和保持效能。

另一個挑戰是將ePRTC訊號傳送到網路中；ePRTC與終端應用程式之間的每個網路元素都可能增加時間誤差，並將降低所提供的總時間。因此，重要的是結合EPRTC與時間和頻率分佈介面，如PTP、NTP和SIMC-E。

我們的緊湊解決方案僅包括兩個振盪石英器件：符合G.811.1ePRC的OSA 3230B ePRC銫時鐘，它連線到OSA 5421或OSA 5430時鐘組合器和符合G.8272.1ePRTC的巨集主時鐘。

為了獲得無與倫比的空間效率，我們的OSA 5421建立了一個緊湊的ePRTC系統，該系統以不同格式提供多個扇出訊號，包括PTP、NTP、SyncE和BITS。這消除了對附加輸出訊號分配裝置的需要。

而且，為了獨特的靈活性和冗餘性，我們的OSA 5430建立了具有冗餘硬體的完全保護的ePRTC解決方案，包括GNSS接收機和時鐘組合器。它具有模組化和可伸縮性設計，支援多個10Gbit/s和1Gbit/s介面上的PTP、NTP和SyncE以及硬體時間戳。

此外，嵌入在所有ePRTC中的Syncjack™同步探測和保證技術能夠檢測和報告提供給ePRTC的不同引用之間的不一致性，以及檢測GNSS欺騙。

有了這些ePRTC解決方案，我們提供了重要的準確性和保護，幫助運營商擺脫他們的GNSS依賴，使5G時代可以真正開始。

Time for 5G: The vital role of enhanced PRTC

Posted by Nir Laufer on September 20, 2018

Tags • 5G • ePRTC • GNSS • Oscilloquartz • Synchronization

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Today’s rapidly evolving mobile networks and backhaul technologies make cell site synchronization a greater challenge than ever before. 4.5G and 5G applications demand new levels of frequency and phase accuracy.

Outside of telecommunications, timing technologies are now equally important. From data center interconnectivity to vital government defense networks, phenomenally precise synchronization is essential across all industries. Our critical national infrastructures, such as energy and water supplies, healthcare and transportation, depend on precise timing for rapid failure localization and effective operation of distributed control processes. Transactional services in finance rely on trustworthy and precise timestamping. Highly accurate and stable network synchronization is also needed for the metrology that underpins the work of scientists in all fields.

And the challenge isn’t only about delivering greater levels of accuracy. Phenomenal robustness and reliability is now just as essential. With the growing danger of GNSS vulnerabilities, due to deliberate spoofing and jamming attacks or the natural threat of solar flares and space weather events, providing the required levels of availability is a difficult task. Solutions relying on GNSS-based synchronization alone are no longer sufficient for the needs of mission-critical infrastructure. Ensuring backup is now a mandatory step towards secure synchronization.

Enhanced timing

Defined by the ITU-T G8272.1 recommendation, enhanced primary reference time clock (ePRTC) systems take reliability and accuracy to the next level. An ePRTC synchronization source can meet the requirements of next-generation mobile networks, offering the precise synchronization needed by today’s industries and removing vulnerability to GNSS outages. With an ePRTC, accurate timing is maintained for at least 14 days. It also produces much higher levels of precision than standard PRTCs. While the time output of PRTCs should be accurate to within 100ns of UTC, this new generation of timing source delivers time to within just 30ns. ePRTC specifications provide a new level of stability, accuracy and reliability.

The key to ePRTC systems is that they construct their own time with a high-performance cesium clock combined with UTC traceable reference such as a GNSS receiver. This helps filter out fluctuations caused by the impact of atmospheric interference, solar storms or ionospheric variation on timing recovered from GNSS. This innovative combination a GNSS-based system with a cesium frequency standard leverages the advantages of both timing methods and hugely improves the accuracy of frequency, phase and time synchronization.

A quantum leap in holdover capabilities

That’s why we’ve created our OSA ePRTC systems – highly precise and autonomous timing solutions that enable operators to bring long-term precision to their existing infrastructure. Upgrading your system with our ePRTC significantly improves accuracy and holdover performance without adding lots of cost and complexity.

An additional challenge is to deliver the ePRTC signal into the network; each network element between the ePRTC and the end application can add time error and will degrade the overall time provided. It’s therefore important to combine the ePRTC with time and frequency distribution interfaces such as PTP, NTP and Sync-E.

Our compact solutions comprise just two Oscilloquartz devices: an OSA 3230B ePRC cesium clock compliant to G.811.1 ePRC, which is connected to either an OSA 5421 or OSA 5430 clock combiner and grandmaster clock compliant to G.8272.1 ePRTC.

For unbeatable space-efficiency, our OSA 5421 creates a compact ePRTC system that provides multiple fan-out signals in different formats including PTP, NTP, SyncE and BITS. This eliminates the need for an additional output signal distribution device.

And, for unique flexibility and redundancy, our OSA 5430 creates our fully protected ePRTC solution with redundant hardware, including GNSS receivers and clock combiners. It has a modular and scalable design and supports PTP, NTP and SyncE over multiple 10Gbit/s and 1Gbit/s interfaces with hardware timestamping.

What more, the Syncjack™ sync probing and assurance technology embedded in all of our ePRTCs enables detection and reporting of inconsistencies between the different references provided to the ePRTC as well as detection of the GNSS spoofing.

With these ePRTC solutions, we’re providing vital accuracy and protection, helping operators escape their GNSS dependency so that the era of 5G can truly begin.

https://blog.advaoptical.com/en/time-for-5g-the-vital-role-of-enhanced-prtc

作者簡介

https://blog.advaoptical.com/en/about/nir-laufer

Responsible for the development of synchronization delivery and assurance solutions, Nir Laufer is director of product line management at Oscilloquartz, an ADVA Optical Networking company. Nir also represents ADVA in ITU-T SG15 Q.13 and contributes to standards development.

負責同步傳輸和保證解決方案的開發，尼爾·勞弗是ADVA光網路公司Oscilloquartz的產品線管理主任。Nir還代表了ITU-T SG15 Q.13的ADVA，並有助於標準的發展。