Sync Training 101 for 2024

Elevate Your Timing Knowledge – Empowering Network Engineers for Success in 2024

Technology evolution and new services provided through a network is the primary driver for modernization in the transport and wireless technologies. This is what triggers a set of new requirements needed to be met for the modern technologies to work, including Time and Synchronization. You will find below a few basic concepts and provide an overview of what is on the horizon for sync network modernization.

Imagine you are conducting a symphony orchestra where each musician represents a different signal or system. Frequency synchronization ensures all musicians are playing at the same tempo, so the music flows smoothly without anyone playing too fast or too slow. See Figure 1 below and you can assume that A and B are different musicians where the tempo makes the length of segments TA and TB the same. This type of synchronization is commonly found in TDM, SONET, Switches and legacy base stations. The most common strategies used over the years for frequency delivery are E1/T1 circuits, GPS/GNSS, Synchronous Ethernet, and PTP.

Using the same analogy with the symphony orchestra, the Time synchronization is like making sure all musicians start playing at the exact same moment, following a shared beat. This ensures harmony and prevents any confusion or dissonance in the music. See Figure 2 below and note that each segment, both TA and TB are starting and ending each segment at the exact same time. This is most common found in Base Station, Network management or computer systems. The typical strategy for delivering this may be GPS with UTC traceability.

Phase synchronization is akin to ensuring that all musicians are in sync with each other, playing their notes at the right moment within each beat. This coordination ensures that the music sounds cohesive and well-coordinated, without any instruments falling out of rhythm. See Figure 3 and note that the alignment in this case would be in Time and Phase. The most common scenarios where we are required to use this type of synchronization is for LTE Advance, CDMA, LET TDD, 5G and the most common strategy to deliver it is via PTP (IEEE 1588).

IEEE 1588 was developed initially for industrial applications, one of the motivations for this was to replace IRIG-B dedicated cooper connection when they had availability of a LAN network. This standard is also known as PTP or Precision Time Protocol. Within the same protocol we work with different industries that may work with different profiles, power industries, video, Telecom. In the last one, we have Telecom 2008, which was the first profile, follow by G.8265.1 that are layer 3 unicast and used for frequency reconstruction. Then we have G8275.1 and G.8275.2 which can be used for frequency reconstruction but are mainly used for time/phase transfer profiles.

Where are Headed?

As technology evolves and new services are provided through the network, we also need to make changes to the transport and wireless technologies. We come from a TDM/SONET network that still has some services that will need to stay in place for the near future. Therefore, we need to make sure that this is considered when modernizing the Synchronization Network.

One of the challenges that we have from legacy architectures is that GPS is the most common source of timing as it was typically found remarkably close at the end applications. So, as the network grows and evolves, we are facing high costs in maintenance and management, but even more important, we start seeing how the vulnerabilities also grow. Networks depending on GPS everywhere without a backup source of timing or firewall systems are exposed to factors like jamming or spoofing that can impact severely the services at all levels, and sometimes without nobody noticing.

The world changes, and so does the technology that supports it, so for every step forward that we take, we must take the time to plan, evaluate the current solution, leverage what we have or can, but also adjust what we need in order to fit successfully into the high-speed world that we are today delivering the best class services.