Resilient Timing for Critical National Infrastructure

Critical infrastructure requires precise timing to operate. This reliance makes the infrastructure vulnerable to disruptions in timing that can be either intentional or unintentional. Intentional disruptions can be caused by GNSS jamming or spoofing or network attacks.. Unintentional disruptions are usually caused by equipment failures or acts of nature.

Back in April 2022, Alliance for Telecommunications Industry Solutions (ATIS) hosted a webinar on this topic, a precursor to the Annual Workshop on Synchronization and Timing Systems (WSTS). The webinar featured top industry experts delivering insight into the latest techniques for adding resilience and robustness to timing infrastructure. It covered the most critical topics in timing resilience, including:

• Redundancy
• Holdover
• Management
• Monitoring
• Alternative reference time sources

Examples address networks used for critical industry applications such as:

• Power grids
• Telecommunications
• Finance systems
• Broadcast/media

The video of the webinar as follows:

Experts participating in the webinar and their presentations are as follows:

• Introduction – Marc Weiss, PhD
• Redundancy and Monitoring – Doug Arnold, Principal Technologist, Meinberg
• Solutions for Backup Resiliency – David Chandler, Product Line Manager, Microchip
• Diversity of Sources (Beyond GNSS) – Anand Ram, Vice President, Business Development, Calnex
• An Example of Resilience and Assurance – Nino De Falcis, Senior Director of Business Development, Oscilloquartz

Please feel free to share other useful resources on this topic in comments.

Related Posts: 

• Telecoms Infrastructure Blog: Synchronization for 5G - Requirements, Solutions & Architecture
• The 3G4G Blog - CWHeritage Talk: The History of Synchronization in Digital Cellular Networks
• The 3G4G Blog: 5G Synchronisation Requirements 

5G Synchronisation Requirements

5G will probably introduce tighter synchronization requirements than LTE. A recent presentation from Ericsson provides more details.

A nice presentation by Ericsson from #WSTS2018: Sync in 5G: What is really needed? - https://t.co/X3XIokELpe pic.twitter.com/6du5ezFfqE

— 3G4G (@3g4gUK) July 17, 2018

In frequencies below 6GHz (referred to as frequency range 1 or FR1 in standards), there is a probability to use both FDD and TDD bands, especially in case of re-farming of existing bands. In frequencies above 6GHz (referred to as frequency range 2 or FR2 in standards, even though FR2 starts from 24.25 GHz), it is expected that all bands would be TDD.

Interesting to see that the cell phase synchronization accuracy measured at BS antenna connectors is specified to be better than 3 μs in 3GPP TS 38 133. This translates into a network-wide requirements of +/-1.5 microseconds and is applicable to both FR1 and FR2, regardless of the cell size.

Frequency Error for NR specified in 3GPP TS 38.104 states that the base station (BS) shall be accurate to within the following accuracy range observed over 1 ms:
Wide Area BS → ±0.05 ppm
Medium Range BS → ±0.1 ppm
Local Area BS → ±0.1 ppm

The presentation specifies that based on request by some operators, studies in ITU-T on the feasibility of solutions targeting end-to-end time synchronization requirements on the order of +/-100 ns to +/-300 ns

There is also a challenge of how the sync information is transported within the network. The conclusion is that while the current LTE sync requirements would work in the short term, new solutions would be required in the longer term.

If this is an area of interest, you will also enjoy watching CW Heritage SIG talk by Prof. Andy Sutton, "The history of synchronisation in digital cellular networks". Its available here.

#CWHeritage Talk: The History of Synchronization in Digital Cellular Networks

CW (a.k.a. Cambridge Wireless) held a very interesting event titled 'Time for Telecoms' at the Science Museum in London. I managed to record this one talk by Prof. Andy Sutton, who has also kindly shared slides and some other papers that he mentions in his presentation. You can also see the tweets from the event on Twitter.

The video playlist and the presentation is embedded below.

The history of synchronisation in digital cellular networks from 3G4G

The papers referred to in the presentation/video available as follows:

• Martin Kingston: The need for Synchronisation in Telecommunications
• Charles Curry: Time from the Sky
• Sébastien Jobert & Kenneth Hann: Synchronisation and Time Distribution in Modern Telecommunications Networks
• Tommy Cook & Tim Frost: Stepping up to the Challenge on Tighter Time Accuracy.
• Andy Sutton: The history of synchronisation in digital cellular networks

Mobile standards & synchronization - Interesting presentation from Ericsson

Mobile standards & synchronization: 3GPP, etc.

View more presentations from Zahid Ghadialy