Comcast's multi-gig network upgrade to cost less than $200 per home passed

Comcast is finally starting to reveal some of the costs required to fuel its ambitious plan to bring symmetrical, multi-gigabit speeds to tens of millions of homes attached to its widely deployed hybrid fiber/coax (HFC) network. And it's increasingly clear that those costs will come in well below a full-fiber upgrade.

Upgrading Comcast's HFC network with an upstream-enhancing "mid-split" that enables symmetrical, multi-gigabit speeds will cost "less than $200 per home passed," Elad Nafshi, Comcast Cable's EVP and chief network officer, revealed Tuesday at the RBC Capital Markets Global Technology, Internet, Media and Telecommunications Conference.

Figure 1: (Source: Comcast)

"That's not all incremental, because in many ways we would need to make that investment for capacity augmentations, anyway," Nafshi added. "That's why we believe that we have a much more cost-effective way of delivering multiple gigabit symmetrical speeds in great scale and do that faster, more reliably and without the customer disruption that a full-fiber overbuild would require."

Under a mid-split, Comcast will expand the amount of capacity dedicated to the upstream – from a legacy range of 5MHz-45MHz to a broader range of 5MHz-85MHz. Using a DOCSIS network built to 1.2GHz with the mid-split and the use of Full Duplex DOCSIS (FDX) will put Comcast in position to roll out symmetrical, multi-gigabit speeds.

Multi-gig service rollouts to start in 2023

Nafshi's cost revelation arrives about two months after Comcast announced it would start to introduce multi-gig speeds in 2023, and to bring that capability to more than 50 million homes and businesses before the end of 2025.

Though the network upgrade costs cited by Nafshi are not all incremental, back-of-the-napkin calculations suggest the upgrade (which does not factor in the expense of any new customer premises equipment) will cost in the neighborhood of $10 billion for Comcast to reach that 50 million home target. That could rise to $12.22 billion based on Comcast's full footprint of 61.14 million homes and businesses passed at the end of Q3 2022. Based on a cost of $1,000 per home passed, a full fiber upgrade across Comcast's full footprint would cost about $61.14 billion.

Nafshi said the mid-split effectively lays the foundation for a future move to DOCSIS 4.0 using the Full Duplex DOCSIS (FDX) option. FDX envisions an HFC network built to 1.2GHz with an FDX band that allows upstream and downstream to be stacked in the same block of spectrum. The Extended Spectrum DOCSIS (ESD) version of D4.0 envisions a network built to 1.8GHz with upstream and downstream traffic continuing to operate in separate, dedicated spectrum.

It was not entirely immediately clear if the approximate $200 cost per home passed involves a full upgrade to DOCSIS 4.0, but today's revelation should give analysts some fresh data to use when calculating network upgrade costs for Comcast and other cable operators.

But Nafshi did note that the "number we shared today is an all-in number."

Update: Light Reading has asked Comcast to clarify if the cost figure cited by Nafshi covers merely the mid-split piece of the network upgrade, or if that number includes an eventual, full network upgrade to DOCSIS 4.0 under the Full Duplex DOCSIS (FDX) option.

Comcast confirmed that the $200 per home passed covers everything – from the mid-split, to network virtualization and the eventual move to DOCSIS 4.0

Heading to today's talk at the RBC conference, analysts and industry experts have been trying to estimate costs for mid-split or high-split upgrades and future transitions to DOCSIS 4.0. In May, Broadband Success Partners estimated that it would take an incremental $150 to $300 per home passed for D4.0 upgrades, and an additional $100 per home passed for the mid-split or high-split. More recently, Credit Suisse speculated that D4.0 network upgrade costs would be just $180 per home passed, though some industry experts warned that such an estimate is likely low. But Credit Suisse's estimate appears to be very close in line with Comcast's anticipated costs for the full DOCSIS 4.0 upgrade.

A fully-fledged DOCSIS 4.0 network will put cable operators in position to deliver speeds of about 10 Gbit/s downstream and 6 Gbit/s upstream. At a tech demo at CableLabs held in April, Comcast showed off measured speeds of 8.5 Gbit/s downstream and 5 Gbit/s upstream.

FDX Amp 'missing piece' to widescale deployment

Nafshi did not go into great detail about how Comcast was able to get those costs so low. However, the cost figure does surface not long after Comcast started to tout tests centered on a new FDX Amplifier that enables the operator to deploy the D4.0/FDX option with as many as six amplifiers present between the home and the node.

The original approach with FDX required a somewhat expensive "node+0" architecture that pulls fiber deeper into the network while also eliminating all amplifiers between the home and the node.

"That [the FDX Amplifier] was really the missing piece to be able to deliver multiple gigabit symmetrical services throughout the entire network without needing to do any type of special construction," Nafshi said.

No need for a full-fiber overbuild

Nafshi said he's confident that Comcast's approach ensures the operator can stay competitive with broadband without having to resort to a full-fiber upgrade.

"The reason why we don't feel that we need to overbuild ourselves with fiber is because we believe we're able to deliver the same services – meaning multiple gigabit symmetrical services with highly reliable service – and do that everywhere, [to] each and every one of our 60-plus million homes without needing to dig up streets and without needing to dig up your front lawn," he said. "That's why we believe that the DOCSIS evolution is the right one for us."

Cable operators are pursuing multi-gig, symmetrical capabilities in part to keep up with the speed performance of fiber competition. But it's clear that most customers don't really need symmetrical speeds.

Nafshi said today's data consumption remains highly asymmetric, with a downstream/upstream ratio today of about 15:1. Even during the height of the pandemic, when millions were working and schooling from home, that ratio was about 12.5:1, he said.

Nafshi also defended Comcast's decision to pursue DOCSIS 4.0 with FDX over ESD. Instead of having to change out splitters and other devices to pass a 1.8GHz signal on HFC, FDX is a simpler approach, he argued.

"All you need is a software download to a virtualize architecture, a new generation of DOCSIS 4.0 FDX electronics in our nodes and amplifiers, and we're ready to go," Nafshi said. "Either way will work, but we believe this is the right way for Comcast."

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— Jeff Baumgartner, Senior Editor, Light Reading