(百度翻译)
5G的时间：增强PRTC的重要作用
当今快速发展的移动网络和回程技术使得蜂窝站点同步成为前所未有的挑战。4.5G和5G应用需要新的频率和相位精度水平。
在电信之外，计时技术现在同样重要。从数据中心的互联性到重要的政府防御网络，在所有行业中，非常精确的同步是必不可少的。我们的关键国家基础设施，如能源和水供应、医疗保健和运输，取决于快速故障定位的精确时机和分布式控制过程的有效运行。金融交易服务依赖于可信和精确的时间戳。对于支持所有领域科学家工作的计量学，也需要高度准确和稳定的网络同步。
挑战不仅仅是传递更高的准确度。非凡的健壮性和可靠性现在也是必不可少的。随着全球导航卫星系统脆弱性的危险日益增加，由于蓄意欺骗和干扰攻击或太阳耀斑和空间天气事件的自然威胁，提供所需的可用性水平是一项艰巨的任务。依赖于基于GNSS的同步的解决方案不再足以满足基础设施关键任务的需要。确保备份现在是实现安全同步的必经步骤。
增强时序
由ITU-T G8272.1建议所定义，增强型主参考时钟(ePRTC)系统将可靠性和准确性提高到下一水平。ePRTC同步源可以满足下一代移动网络的要求，提供当今工业所需的精确同步，并消除GNSS中断的脆弱性。使用ePRTC，保持精确的定时至少14天。它也产生了比标准PRTCs更高的精度水平。虽然PRTC的时间输出应该精确到UTC的100ns以内，但这新一代的定时源将时间交付到仅仅30ns以内。ePRTC规范提供了一个新水平的稳定性、准确性和可靠性。
ePRTC系统的关键在于，它们使用高性能铯时钟结合UTC可跟踪基准（例如GNSS接收机）来构造自己的时间。这有助于滤除大气干扰、太阳风暴或电离层变化对从全球导航卫星系统恢复的定时的影响所引起的波动。这种基于GNSS的系统与铯频率标准的创新组合利用了两种定时方法的优点，并极大地提高了频率、相位和时间同步的精度。
保持能力的量子跃进
这就是为什么我们创建了OSA ePRTC系统——高度精确和自主的定时解决方案，使运营商能够为其现有基础设施带来长期的精度。使用我们的ePRTC升级您的系统，在不增加大量成本和复杂性的情况下，显著地提高了准确性和保持性能。
另一个挑战是将ePRTC信号传送到网络中；ePRTC与终端应用程序之间的每个网络元素都可能增加时间误差，并将降低所提供的总时间。因此，重要的是结合EPRTC与时间和频率分布接口，如PTP、NTP和SIMC-E。
我们的紧凑解决方案仅包括两个振荡石英器件：符合G.811.1ePRC的OSA 3230B ePRC铯时钟，它连接到OSA 5421或OSA 5430时钟组合器和符合G.8272.1ePRTC的宏主时钟。
为了获得无与伦比的空间效率，我们的OSA 5421创建了一个紧凑的ePRTC系统，该系统以不同格式提供多个扇出信号，包括PTP、NTP、SyncE和BITS。这消除了对附加输出信号分配装置的需要。
而且，为了独特的灵活性和冗余性，我们的OSA 5430创建了具有冗余硬件的完全保护的ePRTC解决方案，包括GNSS接收机和时钟组合器。它具有模块化和可伸缩性设计，支持多个10Gbit/s和1Gbit/s接口上的PTP、NTP和SyncE以及硬件时间戳。
此外，嵌入在所有ePRTC中的Syncjack™同步探测和保证技术能够检测和报告提供给ePRTC的不同引用之间的不一致性，以及检测GNSS欺骗。
有了这些ePRTC解决方案，我们提供了重要的准确性和保护，帮助运营商摆脱他们的GNSS依赖，使5G时代可以真正开始。
Time for 5G: The vital role of enhanced PRTC
Posted by Nir Laufer on September 20, 2018
Tags • 5G • ePRTC • GNSS • Oscilloquartz • Synchronization
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
作者简介
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.
负责同步传输和保证解决方案的开发，尼尔·劳弗是ADVA光网络公司Oscilloquartz的产品线管理主任。Nir还代表了ITU-T SG15 Q.13的ADVA，并有助于标准的发展。