Coaxial cable will be around for many years to come. But sometimes, a cable operator simply can’t win an argument with a home builder who insists on being able to advertise that “fiber” has been strung to a spanking-new housing development.
“Home builders are able to get a $5,000 to $10,000 premium on their properties from having fiber to the home,” said Bob Tynan, director of business development in Scientific Atlanta’s transport and access network business unit.
To give cable companies a fighting chance in such bids, several technology vendors have cooked up new kind of fiber-to-the-premises architecture: RF over glass, or “RFoG,” which defines a way to deliver existing radio-frequency signals over fiber-optic links between the cable headend and the customer’s location.
The concept is that cable services, including video and Data Over Cable Service Interface Specification signals, will work exactly as before, using the same provisioning and billing systems, headend equipment, set-top boxes and cable modems.
What’s different is that fiber-optic “micronodes” at a customer’s house convert the lightwaves into electrical signals, rather having than high-level nodes in the hybrid fiber coaxial network perform that function.
“The RF infrastructure stays in place. We’ve just moved the fiber termination to the side of the home,” said Paul Braun, senior product manager in Motorola’s access-networks business.
In some cases, RFoG — also called “cable PON,” referring to passive-optical network systems — may deliver operational cost advantages over HFC. For example, PON equipment needs less power and cooling than the nodes and outside plant used in a typical cable network. Also, fiber delivers a “cleaner” signal, because it’s impervious to the kind of interference that can plague RF over coax.
For the near term, the major selling point of RF over glass is to win business in new housing developments and other “greenfield” locations.
“What we’ve heard from operators is, ‘Get me a solution quickly that will at least on a perception basis let me compete with Verizon,’” Motorola senior product manager Shawn Esser said.
Motorola, which expects to deliver an RFoG solution in 2008, estimated the cost of cable-over-PON would be 15% to 20% higher than a “node plus one” HFC buildout (i.e., one active amplifier per node). A full PON would be around 50% higher than HFC depending on how an operator deployed it, Braun said.
Other vendors promoting RFoG include Alloptic, CommScope, Cisco Systems and Scientific Atlanta, and Arris Group.
Alloptic, an optical networking equipment maker in Livermore, Calif., already sells a device called the MicroNode to the cable industry. The paperbook-size unit, which the company sells for between $125 and $250, supports a single-fiber architecture and delivers two-way RF video, DOCSIS and voice traffic.
Of the 50 new customers Alloptic added in 2007, more than half are deploying the hybrid cable-PON technology, including Armstrong and BendBroadband.
Meanwhile, CommScope said it has successfully deployed its BrightPath RF-over-optical system with three major broadband cable operators (which is wouldn’t name) and has installations in progress with three other cablers. The BrightPath solution uses Aurora Networks’ optical nodes and headend equipment with CommScope’s outside plant products.
Operating an RFoG network is less expensive than HFC, according to Alloptic. For one thing, passive optical network equipment consumes less than 80% the power required by the electronics in an HFC environment. Standard PONs provide a reach of up to 20 kilometers using unpowered components, whereas HFC networks require RF amplifiers every 1,000 feet or so to maintain signal quality.
Even the initial buildout costs of an RF-over-glass network may be cheaper, IDC analyst David Emberley said. “In a greenfield environment, you’re not going to run cable -- it’s going to be fiber,” he said.
Some industry executives, though, maintain that HFC may still be the preferred route even in new builds.
In a high-density neighborhood, for example, HFC nodes and amplifiers may cost less on a per-subscriber basis than PON, said Carl Meyerhoefer, vice president of marketing and business development for CommScope’s broadband division.
On the other hand, in more rural areas, where HFC requires more electronics, “the greater distance of fiber becomes very cost-effective,” he said.
The supposed operational savings of PON are debatable, Scientific Atlanta’s Tynan said, since optical network terminals in an RFoG setup are still active devices that draw power and need servicing. In addition, he noted, an optical-network deployment would require new training for technicians. “We still feel the HFC plant is very robust,” he said.
Another potential drawback is that RFoG isn’t a standardized architecture. The Society of Cable Telecommunications Engineers, which now refers to the concept as “Advanced Fiber Access,” has established a working group to outline standards that should apply to such hybrid cable-optical networks.
All the same, Scientific Atlanta is prepping its own RF-over-glass offering with a lower-cost, purpose-built ONT to be available by the end of next year.
As Tynan acknowledged, “There are good reasons to look at PON for future-proofing… The more copper you can get out of the plant, the better.”