Vodafone trials sovereign fibre-based alternative to GPS timing

• VodafoneThree is work with the National Physical Laboratory (NPL) on the deployment of a telco terrestrial timing solution
• Most telcos rely on US-owned GPS for timing signals
• Vodafone will look to expand terrestrial timing solutions to other European operations

VodafoneThree, the UK operation of the Vodafone Group, has partnered with the National Physical Laboratory (NPL) to trial a new terrestrial, fibre-based alternative to Global Navigation Satellite System (GNSS) timing.

Many in the telco community use satellites for accurate timing signals. The default for UK operators is the US-owned Global Positioning System (GPS), one of the major GNSS constellations, which leverages a network of satellites to transmit signals decoded by receivers to provide positioning, navigating and timing services (PNT). The European Union’s Galileo constellation is also a major GNSS.  

As part of a trial looking to diversify its timing signal sources, VodafoneThree worked with the NPL to develop one of the industry’s first network time sources to be provided by a terrestrial national metrology institute (NMI) as an alternative to GNSS timing.

Vodafone said it is actively reducing its reliance on GNSS for time synchronisation across the VodafoneThree network in the UK, and will expand this out to other Vodafone markets around Europe by partnering with the European Metrology Institutes.

Andrea Donà, chief network officer at VodafoneThree, said: “Our work with the National Physical Laboratory marks a significant step in reducing over reliance on GPS-based timing and strengthening the foundations of our future-ready 5G standalone network. By testing a terrestrial timing solution, we’re helping to ensure that our £11bn investment delivers a network that is not only faster and more reliable but also more secure and resilient for our customers.”

PNT is seen as vital to the functioning of critical national infrastructure, but the UK is almost entirely reliant on the US-owned GPS. This trial comes as politicians and telcos hone in on the importance of network sovereignty, especially as satellite systems are regarded as increasingly prone to interference.

NPL has provided the UK’s national time scale, UTC (coordinated universal time), for over 30 years. For the past eight years, it has developed what it calls NPLTime, which is an end-to-end fibre-based timing service, used by the finance sector for regulatory compliance.

The partnership with Vodafone will see the NPL develop a telecom version of its NPLTime service that aligns with ITU standards for signal accuracy, stability, resilience and traceability, while maintaining accuracy within 40 nanoseconds.

Dr Peter Thompson, NPL’s CEO, said: “Accurate and resilient timing is fundamental to the UK’s digital infrastructure. This partnership with Vodafone showcases how UK innovation can deliver secure and resilient timing solutions. By leveraging NPL’s expertise in time dissemination we are helping the telecoms sector to strengthen the foundations for future technologies.”

Vodafone is not the only operator looking at this, with concerns about both sovereignty and resilience key factors, according to Roberto Kompany, principal analyst for mobile infrastructure at Omdia.

Kompany told TelecomTV that the war in Ukraine has led to incidents of GPS jamming in places like Lithuania, Norway, Poland and Sweden, prompting governments, regulators and operators to consider how to replace GNSS with network timings.

In a recent report, Kompany looked at the requirements of CSPs for 5G synchronisation, the complexities in delivering a networked-based synchronisation, and a look at the regulatory environment and vendor landscape (the full report is available here).

“As you are moving to standalone 5G architecture and deploying more stringent, low latency use cases, the clocks for radios need to be even more precise,” Kompany explained. “GPS is low power but it can be quite easy to jam, which is why operators are looking at more network-based options.

“Atomic clocks and other network solutions are used in other verticals, and there is also political involvement,” he added

For example, in the US a 2020 Executive Order directed federal departments to ensure that critical infrastructure (power grid, communications, transportation) can withstand disruption or manipulation of PNT services. India and China have also been working on this, added Kompany.

“Resilience is really important here – there is a whole value chain of devices that could stop working if you interrupt the timing synchronisation, and this will become even more important as we look at 6G, which will bring even lower latencies,” he noted.

- James Pearce, Editor, TelecomTV