5G

This is the first in a 3-part blog series.

Timing & Synchronization

If someone played a word association game on the topic of mobile telecommunications technology, the first things to come to mind would likely be cell towers, satellites, antennas, and of course smart phones. Most people, even in the industry, would never think of the timing and synchronization of those networks, which are fundamental to the entire system.

Why are timing and sync so out-of-mind despite their importance? They’re invisible, for one. In addition, you don’t read about timing and sync issues because the industry has largely solved the problem of keeping the network signals synchronized from tower-to-tower. The technique to achieve that coordination is called “frequency synchronization.” Frequency information used to be delivered by the wireline TDM circuits connecting the towers, a.k.a. backhaul. When Ethernet became a more effective transport technology for the backhaul function, the timing source was lost. Now carriers rely on satellite (GNSS) signals as the timing source, and it’s been working great for the current version of network technology, so no one’s give network timing a second thought for years.

How 5G Changes Timing & Sync

With 5G, timing and sync can no longer be ignored. As mobile networks evolve to deliver more bandwidth and services to the end-user, timing and sync will take center stage — whether we like it or not. This applies to both the backhaul and fronthaul portions of the network (eCPRI and C-RAN architectures). Network timing is also critical outside of mobile networks where applications dependent on timing ride on a packet-switched network.  For example, cable operators are replacing hybrid-fiber coax (HFC) with Ethernet in Remote-PHY architectures. But in doing so, they lose the timing information formerly carried by the HFC. Likewise, when power utility companies migrate from legacy SCADA networks to Ethernet, they gain the cost and scalability advantages of Ethernet but lose timing, which they need.

For mobility, consider how much faster 5G will be. With 3G, (which has largely been retired but is still in use in some pockets of the world) it would take 26 hours to download the two-hour long “Justice League” with all its sound and CGI effects. With 5G, it will only take mind-blowing 3.6 seconds to download. That’s just theoretical, of course, but the point is that 5G promises to deliver a lot of data very quickly, which will require the network to be much more tightly synchronized than it is now. The current method just won’t suffice.

For a more in-depth study of this topic, please download this white paper, “Timing and Synchronization Standards in Wireless Networks” by Dr. Reza Vaez-Ghaemi. 

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