New-Generation DOCSIS Cable Technology vs. FTTH

Cable operators can relax for the time being about the new DOCSIS 3.1 telecommunications standard coming down the pike. Your fiber networks, which already use various versions of the DOCSIS standard, are going to be competitive physical network structures into the foreseeable future.

DOCSIS 3.1—which includes LDPC encoding, very high modulation orders (e.g., 4096 QAM), more than 1 GHz of usable spectrum and support of QoS and low latencies—is the latest digital communications technology, but it’s not a replacement for  your existing hybrid fiber coax (HFC) architecture that uses coaxial cable to connect to homes. The former is a transport mechanism (protocol); the latter is an architecture that connects multiple locations.

As fiber equipment has gone down in price, more service deployments are utilizing fiber to the home (FTTH), vs. coax (copper) cable. Fiber allows for significantly faster transmission speeds, so has transformed data, video and voice services.

Cable operators with HFC networks now have a viable alternative to FTTH with DOCSIS 3.1, as it enables speeds competitive with fiber speeds on HFC architecture. DOCSIS 3.1 is backward compatible with DOCSIS 3.0 and can be deployed on today’s HFC networks without an upgrade (so, no tearing up the streets).

The availability of high throughput from DOCSIS 3.1 would appear to make an upgrade to FTTH an obsolete idea. But, not so fast …

Upgrades from existing DOCSIS 2.0 or 3.0 equipment to DOCSIS 3.1 equipment are costly. They’re also not that easy: To take full advantage of capabilities requires conversion from analog to digital transmission, and additional fiber deployments to get nodes closer to the subscriber.

So, should operators skip DOCSIS 3.1 and pursue FTTH?

Perhaps that’s the wrong question to ask. In some cases, DOCSIS over a glass architecture would be a viable option for delivering broadband services to homes over fiber. Consequently, it’s not improbable to use DOCSIS and FTTH together. So, the right question for operators is what architecture is needed and which transport technologies work over that architecture. Other transport technologies include EPON, GPON and Ethernet; other architectures include HFC, RFog and PON.

DOCSIS 3.1 could make sense for operators facing bandwidth competition but having limited capital, delivering higher speeds while delaying the more expensive FTTH transition. In the absence of serious bandwidth competition, deploying lower-cost EPON technology in new areas might be the better choice, allowing operators to slowly migrate existing areas to EPON.

Determining the right approach might involve a few challenges, but the good news is that cable operators have many tools at their disposal. Whereas DOCSIS 3.1 enables state-of-the-art speeds to be delivered over HFC networks, DOCSIS Provisioning of EPON (DPoE) allows EPON to be operated with the same back office as a DOCSIS network. Don’t stop your analysis there, however; the list goes on: RFoG enables FTTH with HFC back office and HFC consumer premises equipment, for example.

For cable operators, DOCSIS 3.1 can be a game-changer, maximizing both the upstream and downstream throughput in their networks, without expensive changes to the HFC network infrastructure. But you also have various other options for enhancing HFC networks. You won’t go wrong if you put customer service at the forefront of any technology change.