Cable FTTP Goes Standard

Vendors that make Radio Frequency Over Glass (RFoG) gear may not be setting any sales records yet, but at least they now have a technical standard on which to lean.

After more than two years of discussion, with a series of occasionally testy technical debates thrown in along the way, the Society of Cable Telecommunications Engineers (SCTE) confirms that it approved the RFoG standard, now labeled SCTE 174, in late December. It's now in the hands of American National Standards Institute (ANSI) , which could apply its stamp in mid-March, according to SCTE VP of Standards Stephen Oksala. (See SCTE Moves on RFOG, Who Makes What: RFoG Systems, RFoG Gets the Squeeze and RFOG Comes Rolling In .)

Cable MSOs now have a standard way to deploy fiber-to-the-premises (FTTP) networks and deliver their services using their existing headends, back-office systems, set-tops and Docsis cable modems and embedded multimedia terminal adapters (E-MTAs, or voice models). Targeted primarily to greenfield deployments, rural plant extensions and business service links, RFoG eliminates powered amplifiers and gives cable operators a much "cleaner" plant. What it doesn't do is give cable much of an immediate capacity boost, though the architecture does allow for PON overlays.

Filling a niche
So far, RFoG has been a niche play for MSOs and vendors. "The new housing market is still in the tank, so RFoG hasn't really taken off yet," says Heavy Reading Senior Analyst Alan Breznick. "But it could lay the groundwork for future deployments of PON." (See Costs Could Keep RFoG a Niche Player .)

Vendors don't think the standard will serve as a catalyst for massive RFoG adoption anytime soon. "It wasn't the standard that was holding [RFoG] back," says John Dahlquist, vice president of marketing of Aurora Networks Inc. , which makes RFoG equipment. "I don't think the SCTE adopting a standard will change the housing industry." About 90 percent of Aurora's RFoG sales activity is tied to rural plant extensions, he adds

Still, the technology is seeing some opportunities with operators that want to bridge to PON. IOCs, for example, are starting to use RFoG in conjunction with PON and relying on an RF overlay for video, says Shane Eleniak, VP of advanced broadband solutions for CommScope Inc. , another RFoG supplier.

Regardless of the near-term market opportunities for RFoG, a standard does erase important product discrepancies between suppliers, and may set the stage for the deployments that were put on ice until the SCTE completed its work.

Among the issues that got ironed out during the standards process was the approval of the 1310nm and 1610nm wavelengths for the RFoG return path. The acceptance of 1310nm gives operators access to low-cost lasers, while 1610nm gives MSOs the option to layer on PON.

The standard also accepts FM or AM modulation in the return path. That's good news for Cisco Systems Inc. (Nasdaq: CSCO), one of few RFoG vendors that developed an FM version. Just about everyone else in a group that includes Aurora, Arris Group Inc. (Nasdaq: ARRS), CommScope, Pacific Broadband Networks (PBN) , Motorola Mobility LLC and Communications Test Design Inc. (CTDI) , among others, went with AM.

Elements such as device turn-on and turn-off times and device power levels, which were all over the board, are now standardized, and the standard complies with Docsis 3.0 and its use of bonded carriers.

"We now have a common answer and a common set of expectations for all of those things," Eleniak says, noting that CommScope did most of its major tweaking last year to make sure its RFoG products were up to snuff when the standard was completed. "I think we're there," he said.

Next steps
Oksala says the SCTE is already starting work on standard enhancements. In January, the Society's Engineering Committee approved a follow-on project to consider latch-ons such as Multimedia over Coax Alliance (MoCA) interoperability and remote monitoring and management for RFoG ONUs.

Meanwhile, the International Electrotechnical Commission (IEC) committee for audio, video and multimedia systems and equipment is contemplating incorporating RFoG into the IEC 60728 international cable standard. That's expected to come up at its mid-May meeting in Germany.

"We hope things will work out that this [RFoG standard] gets to the next, international level," Oksala says.

— Jeff Baumgartner, Site Editor, Light Reading Cable

comtech3 12/5/2012 | 5:11:02 PM
re: Cable FTTP Goes Standard

As far as the incumbent MSOs such as Comcast , TWC, et al, RFoG deployment may never happen in our life time. Firstly, the cost involved,which is not much more than their present HFC backbone,but nonetheless , is an added expenditure. Secondly,HFC still have some flexibilities left in it in terms of bandwidth management. These includes 256 QAM and channel bonding in the downstream spectrum, 16 or 32 QAM and channel bonding in the upstream spectrum,and DOCIS 3.0. There is also talk of  switched video,which is another way have preserving BW.

The thing that kills the current HFC architecture, is the constant outages whenever there's a storm, or an amplifier blows a fuse. Preventative maintenance is another sore point which entails bringing down the plant to replace a node or line extender. There was once a concern about the noisy upstream spectrum in the 5-45 MHz regions,but not anymore.Comcast, especially, had launched an aggressive noise mitigation program a while back, which allowed them to deploy 16 QAM in the upstream.


Jeff Baumgartner 12/5/2012 | 5:11:01 PM
re: Cable FTTP Goes Standard

True. Most RFoG deployments, particularly from the tier 1s, will be spotty and opportunistic. Well, count tier 2/3 in there, too, unless they are rehabbing ancient plant.  Generally speaking, HFC's still got a lot of legs left. JB

comtech3 12/5/2012 | 5:11:00 PM
re: Cable FTTP Goes Standard

RFoG is sort of a misnomer because it's architecture is the same as that of Verizon's FIOS FTTH. The only exception is the head-end equipment. RFoG uses the ONU  at the customer's premises as does FIOS. But according to Aurora Network Technologies, there are limitations with the type LASERs used in the return path for RFoG. However, there solution is to at lease have one active node in the plant that receives the signals from the micro-nodes in the home onwards to the head-end.

As mentioned before, the likelihood of major MSO migrating to RFoG anytime soon are remote. Mark you, it would cost them less than what it cost Verizon and other Telco to run fiber because of their FTTN HFC architecture will only require removing all actives after the node and extend the fiber deeper. However, to do so, the labor cost associated with running aerial spans and trenching is the inhibiting factor.  Installing micro-nodes in these home,only to have customers cancel their service is not a nice experience at all,and Verizon,especially, is losing money because they leave the device there and have not gone back for it.

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