Bit Rate

FiOS Guys Thumb Noses at DOCSIS 3.0

1/30/2009 3:25 PM

But of course. As cable widens the rollout of ultra-fast DOCSIS 3.0-based broadband, Verizon insists its FiOS fiber-to-the-home network is literally beyond compare.”The cable companies are making much of CableLabs’ DOCSIS 3.0 technology that they say will create parity with Verizon FiOS Internet… Not surprisingly, we have a different perspective,” senior vice president of media relations Eric Rabe wrote in a blog post yesterday referring to Charter’s launch of Ultra60, a 60-Mbps downstream service, in St. Louis this week.

On paper, that makes Charter’s top tier faster than Verizon’s, the 50-Mbps downstream FiOS Internet.

Verizon thinks the comparison is somehow invalid. Rabe first quotes Brian Whitton, Verizon’s executive director of technology, who says cable operators need to free up space before they can offer DOCSIS 3.0 channel bonding.

Whitton claims that “many of the cable companies’ existing customers are adversely impacted because the channels seized for DOCSIS come at the expense of video channels that their customers will no longer get unless they upgrade to the more costly digital video product line.”

First of all, that’s a weird argument if you’re trying to make the case for why FTTH is superior to DOCSIS 3.0.

It’s true that many cable systems have been migrating channels from analog to digital, to free up space. The FCC pushed the cable industry to suspend this practice until after the digital TV transition, so customers wouldn’t somehow think they needed to upgrade to a digital cable tier as part of the broadcast transition.

But it’s incorrect to suggest that retiring analog TV channels is the only way to add capacity to an HFC network. For example, an MSO could add capacity for DOCSIS 3.0 by performing node splits; by upgrading the plant to 1 GHz, as Cox Communications is doing; by distributing digital-to-analog adapters, as Comcast is doing; or through switched digital video.

Rabe also comments that DOCSIS 3.0 services are just being deployed and won’t be available to “all customers.” But neither is FiOS: The network passed 40% of the homes in Verizon’s footprint at the end of 2008, and FiOS Internet isn’t even available to all of those yet. And Comcast claims it is able to offer wideband to 10 million premises, and counting.

On technical grounds, the Verizon guys bring up the shared-cable-architecture-leads-to-congestion line of argument, which telcos have trotted out for years. “Too many customers tapping the link for 60 Mbps service at the same time will ultimately impact their lower-speed neighbors’ service as they fight for trunk capacity,” Rabe says.

But FiOS ultimately is a shared-capacity network too, just higher up in the network. And while a DOCSIS 3.0 deployment would require more attention to ensure capacity meets demand for all subscribers served by a node, if it’s managed properly there’s not an issue in terms of the service level a customer receives. (Not that cable providers have always managed this well in the past — many ex-cable broadband customers recall their connections dropping precipitously during “primetime” hours of peak bandwidth consumption.)

Meanwhile, Rabe claims FiOS’s 2.4-Gbps GPON network connection to each subscriber is “15 times the size of cable’s.”

Well, no. That’s if you’re talking about four bonded channels. DOCSIS 3.0 can bond up to eight, 16 or theoretically even more channels. Cisco is getting ready to submit a 300-Mbps-plus, eight-channel DOCSIS 3.0 modem for qualification to CableLabs. (Also note that GPON is not deployed everywhere in the FiOS territory; many areas still run the older 622-Mbps-downstream BPON.)

Rabe is on strongest ground when he points out that cable-modem technology has more limited upstream capacity. “Already today Verizon FiOS delivers up to 20 Mbps upstream compared, for example, to Charter’s reported top speed of 5 Mbps,” he writes.

Here, the FiOS advantage is real but relatively meaningless for now. Very few people today have any use for those kinds of upstream speeds. The utility of mega-fast downstream speeds is also dubious for anything except huge file downloads, e.g., pulling down HD movies from iTunes, but the downstream number is really the main thing that matters in the marketing war over speed.

If and when the market requires more upstream, DOCSIS 3.0 can kick upstream speeds to 120 Mbps or more. (Again, with the caveat that new space on the plant would need to be carved out.)

Don’t get me wrong. Verizon is within its rights to tout the undeniable technical superiority of FTTH (no signal interference, simpler/lower-cost maintenance). Hey, if I’d spent $18 billion building out a network, I’d want to brag about it too.

In a practical sense, though, cable will be able to hold its own against FiOS or other fiber-to-the-home competitors with DOCSIS 3.0 for the next several years at least.

September