From the start, cable engineers took potshots at Verizon's fiber-to-the-home FiOS plan. HFC could do just a well, they maintained. It was too expensive to run that much fiber, they said. Verizon just has deep pockets but even the deepest pockets would hit bottom, they concluded.
Turns out they were right about the money but they were either wrong or wrongheaded about FTTH. With more applications grabbing more bandwidth and creating more stress on traditional cable networks, the industry is being forced to re-examine the H and C portions of HFC and concentrate on the F, as in fiber.
The biggest problem is that cable's been around more than half a century and it's being doing things the same way almost all that time. If telcos were stuck with reams of twisted pair copper, cable is jammed between coax and RF technology that doesn't lend itself to a complete change out to more streamlined fiber and IP.
The choice is to either tear everything up, or, as some rural systems are already discovering, follow a migratory route with something like RF over Glass (RFoG-pronounced 'ARE Fog'), a deep fiber design where the coax portion is replaced by a single-fiber, passive optical architecture (PON) similar to the one Verizon uses with FiOS but the RF electronics remain in place. The secret sauce, as someone has to say at least once in every PowerPoint presentation, is to use different wavelengths to share the same fiber so that the infrastructure can support both RFoG and PON depending on where the signal's going.
"RFoG doesn't disrupt anything else you're doing in your networks: your set-top box is the same, your cable modems, your IP telephony. It doesn't change any of your back office operations but you've now upgraded maybe 1,000 homes (in a node) to a fiber-to-the-home system," said John Dahlquist, vice president of marketing for Aurora Networks, a company that's been pushing RFoG since about 2006.
Dahlquist cut his teeth designing amplifiers for the old General Instrument but now believes that "amplifiers are dead;" remnants of the old coaxial way of doing things that introduce nothing but noise and cost and power consumption to a cable system.
"When you build fiber deep and compare it to HFC we have 50 percent of the power and only about 25 percent of the devices left," he said. "Once you get rid of all the RF amplifiers, you now have coax and taps and splitters between the node and the home."
RFoG is seen as a fiber shot in the arm for rural systems covering scattered homes but it's also a good way for cable operators everywhere to approach symmetrical signal transport for increasingly heavier data loads. Eliminating analog channels allows operators to move more spectrum for the return--leaving breathing room for upstream data transport.
While Dahlquist didn't say it, the implication is that cable operators could cherry pick the best subscribers to target with new applications delivered over a fiber rich transport while maintaining the RF plant for later migration. It's a plan that will probably gain more traction now that FiOS has shown what fiber can do.
"You can't argue with the basic principle of fiber-to-the-home," Dahlquist said. "It's just a matter of cost. Everybody will tell you that eventually if there's a wireline to the home, it's going to be fiber."
It's just not going to happen today, as Verizon has clearly demonstrated. -Jim