G.Fast over Coax

There is yet another new technology available to carriers – G.Fast over coaxial cable. Early trials of the technology show it works better than G.Fast over telephone copper.

Calix recently did a test of the new coaxial technology and was able to deliver 500+ Mbps for up to 2,000 feet. This is far better than current G.Fast technology over copper which can handle similar data speeds up to about 800 feet. But telephone G.Fast is improving and Calix just demonstrated a telephone copper G.Fast that can deliver 1 Gbps for about 750 feet.

But achieving the kinds of speeds demonstrated by Calix requires a high-quality telephone copper network. We all know that the existing telephone and coaxial networks in existing buildings are usually anything but pristine. Many existing coaxial cables in places like apartment buildings have been cut and re-spliced numerous times over the years, which will significantly degrade G.Fast performance.

This new technology is definitely going to work best in niche applications – and there may be situations where it’s the clearly best technology for the price. There are a surprising number of coaxial networks in place in homes, apartment buildings, schools, factories and older office buildings that might be good candidates for the technology.

A number of telcos like CenturyLink and AT&T are starting to use G.Fast over telephone copper to distribute broadband to apartment buildings. Since as the incumbent telephone company they can make sure that these networks are available to them. But there might be many apartment buildings where the existing coaxial network could be used instead. The ability to go up to 2,000 feet could make a big difference in larger apartment buildings.

Another potential use would be in schools. However, with the expanding demand for broadband in classrooms one has to wonder if 500 Mbps is enough bandwidth to serve and share among a typical string of classrooms – each with their own heavy broadband demand.

There are also a lot of places that have coaxial networks that you might not think about. For example, coaxial wiring was the historic wiring of choice for the early versions of video surveillance cameras in factories and other large businesses. It would not be hard to add WiFi modems to this kind of network. There are tons of older hotels with end-to-end coaxial networks. Any older office buildings is likely to have coaxial wiring throughout.

But there is one drawback for the technology in that the coaxial network can’t be carrying a cable TV signal at the same time. The coaxial G.Fast operates at the same frequencies as a significant chunk of a traditional DOCSIS cable network. To use the technology in a place like an apartment would mean that the coaxial wiring can no longer be used for cable TV delivery. Or it means converting the cable TV signal to IPTV to travel over the G.Fast. (but that wouldn’t leave much bandwidth for broadband.) But still, there are probably many unused coaxial wiring networks and the technology could use them with very little required rewiring.

It’s more likely that the coaxial G.Fast could coexist with existing applications in places like factories. Those networks typically use MoCA to feed the video cameras, at frequencies that are higher than DOCSIS cable networks.

But my guess is that the interference issue will be a big one for many potential applications. Most apartments and schools are going to still be using their networks to deliver traditional video. And many other coaxial networks will have been so chopped up and re-spliced over time to present a real challenge for the technology.

But this is one more technology to put into the toolbox, particularly for companies that bring broadband to a lot of older buildings. There are probably many cases where this could be the most cost effective solution.