Comcast shows off a 3 gigabit broadband connection. That’s fast!

In an attempt to show that cable technologies can stay competitive with the fiber-broadband, Comcast (s CMCSA) chief executive Brian Roberts today demonstrated a 3 gigabits per second (Gbps) connection. He also talked about the next generation in video delivery during his keynote speech at the Cable Show in Washington DC.

Roberts used the 3 Gbps connection which he used to open an email and download a 4K video file. I’m sure the email didn’t tax the connection. However the 4K video download would certainly tax Comcast’s existing broadband cap of 300 GB per month (it is trialing other versions of the cap) given that a single 4K movie download weighs in at about 100 GB per movie. Yet, 4K is the next generation video delivery standard after HD and companies such as Netflix are already starting to deliver content in 4K.

On the broadband side, Comcast knows that to keep up with the demand for faster broadband networks, it will have to push the envelope on gigabit speeds. Google is building out gigabit networks in three cities, while AT&T has threatened to build on in Austin, Texas. Meanwhile private companies and municipalities are pushing their own gigabit projects.

So while Comcast currently delivers a top speed of 305 Mbps in some markets, showing off a multi-gigabit connection is important to show that cable technology can keep up with the fiber to the home build outs. The 3 Gbps connection was delivered over a DOCSIS hybrid fiber coax (HFC) network. But in the real world such speeds might be impossible without an upgrade to the next generation DOCSIS 3.1 technology.

As impressive as this demo is, the reality of deploying 3 gigabits per second may require a new technology (the coming DOCSIS 3.1 standard) as well as some hard thinking on how Comcast wants to use the spectrum available inside its cables.

The DOCSIS standard boosts broadband speeds by allocating more channels comprised of 6MHz of spectrum together to deliver broadband. So more channels, equal more speeds. But, those 6MHz chunks of spectrum also deliver between 2-4 television channels as well, so at a certain point Comcast has to decide if it wants to boost broadband at the expense of adding or delivering television channels.