Fiber Optics: Choosing a Direction
Keeping up with skyrocketing bandwidth demands, as well as increased pressure from the competition, means cable operators are constantly sifting through the various fiber-optic strategies that are available in the market today, which include short-term and long-term options.
Whether it’s “Fiber Deep,” RF over glass (RFoG) or RFPON, full-blown fiber-to-the-premises, or passive optical network architectures, cable operators know they need to add more fiber to their networks. But there’s not a one-size-fits-all fiber solution as vendors and cable operators are looking at different strategies for different scenarios, such as greenfield, brownfield, multi-dwelling units and business services applications.
“We definitely have different strategies for different situations,” said John Civiletto, Cox Communications’ executive director of core video systems. “Our general strategy today is still HFC-based, without a doubt, although even our coax strategy has some pretty significant fiber components to it. We definitely see the value of fiber, and I would argue that everyone should be thinking about it.
“When we’re looking at our network today, we’re really not talking about the needs or capacity for the next couple of years,” Civiletto continued. “We tend to look at a 10-year window forward. We’re trying to understand what needs to happen in the network and work toward those goals. If you’re just thinking about the next few years in the future, you’re always going to be behind.”
Here’s a rundown of what some cable operators and vendors are doing with fiber-optic technologies.
SHAW TRIALS 1-GIG SERVICE
While Google’s announcement in February about a 100-gigabit fiber-to-the-home trial kicked up a lot of dust, Shaw Communications has a 100-gig trial that is slated to start this month. Shaw’s Gigabit Internet service will feature speeds that are 10 times faster than its High-Speed Nitro service, which currently tops out at 100 Mbps.
Shaw’s Dennis Steiger, vice president of engineering, said his company has been working on designing a PON that will allow it to overlay RFoG in the short term, with existing CPE equipment, and then down the road deploy Gigabit Ethernet services.
“DOCSIS 3.0 has been rolled out by Shaw for some time, and we’re getting some pretty good traction around our 100 Mbps service, but we’re thinking about what happens next?” Steiger asked. “As you’ve probably read, Google has talked about 1-gig fiber-to-the-home builds and things like that. We’ve been giving that quite a bit of thought, too, and we’re looking more at what fiber brings in that realm, as well.”
Steiger said the 100-gigabit trial is to an MDU for a “fiber-to-the-suite” service, with an undisclosed community getting its own fiber-to-the-home trial later this year.
“The future of high-speed data isn’t going to be about DOCSIS, or DOCSIS 4 or DOCSIS 5,” Steiger said. “It’s really going to be about an Ethernet Gig service to the home, and the passive optical networks that we build will allow us to do that. They allow us to bring both RFoG and high-speed data in the gigabit range into the home, so we’re also building for the future, as well. I don’t think gigabit per second is all that far down the road.”
In addition to the gigabit trial, Shaw is in “deep design” on RFoG, with trials in greenfield, MDU and brownfield environments also starting either this month or soon after.
“Fiber really changes what’s possible for us and for all cable operators,” Steiger said. “Coax has always been a very intensive technology to upgrade in terms of increased bandwidth. With fiber, it’s more of an act of replacing the electronics because the network itself is a passive optical network, so we don’t have to go in and work on the actual plant as much. It’s just a matter of upgrading electronics. That allows us to piggyback on things like high-speed Internet services today up to a gigabit a second, and in the future even more.
“And, of course, it’s backwards compatible with all of our RF technologies like DOCSIS and set-tops through RFoG, and eventually it will give us the ability to deploy IP-based set-top boxes.”
ONWARD THROUGH THE RFoG
RF over glass was developed by the Society of Cable Telecommunications Engineers in order to help cable operators run fiber closer to homes without swapping out customer premises equipment (CPE) or making any changes to headends and provisioning systems.
“RFoG is taking fiber all the way to the home, except you can use the same set-top boxes and E-MTAs that you would use in a traditional HFC plant,” said Aurora Networks vice president of marketing John Dahlquist. “The only difference is you put a mini node, or micro node, on the side of the house.”
The micro node converts the signal back to RF for distribution around the house. Once the network is converted to FTTH, the micro node is changed out for a different device. Another plus for RFoG is that it doesn’t entail trenching up subscribers’ yards during installation.
“If it was greenfield, today I’d go with RFoG, but it depends on the density,” Dahlquist said. “If the density is really high, RFoG becomes cost-prohibitive because you would have to have so many new receivers, but if it was a new build with 40 to 50 homes, RFoG is a very good solution for that, and it’s as future-proof as you can get.”
A recent study by Aurora Networks found that while RFoG is a good “future-proof” option, it doesn’t necessarily increase bandwidth that much unless it’s overlaid with a PON, and it’s more costly than Fiber Deep.
Civiletto said Cox has had an RFoG trial underway for about a year now in a business environment, but he wasn’t convinced it was ready for large-scale deployments just yet.
“I think the jury is still out on the cost of deploying RFoG on a large scale,” he said. “There have been a number of trials with different MSOs, but we think RFoG still has to break over some cost-competitive points right now that it hasn’t quite achieved. One of the areas that vendors claim RFoG can be more efficient in is low-density residential, but that remains to be proven in scale. We’re definitely of the opinion that it’s more for commercial offerings.”
But while RFoG looks like a short-term, niche player, it does play a role as a transitional technology for other fiber strategies. Shaw’s Steiger said it would be about five years before his company starts using IP-based set-top boxes, and that RFoG could have a shelf life of up to 10 more years in order to support DOCSIS-based applications such as tru-2way and EBIF.
BendBroadband first deployed a hybrid RF-PON with vendor Alloptic in a greenfield residential environment in 2006, followed by a greenfield business deployment a year later. Like Shaw, BendBroadband deployed RF-PON as a bridge to another fiber technology down the road.
“RF-PON, in a greenfield, provided a foundation for future technologies, specifically toward GEPON,” said BendBroadband CTO Frank Miller. “GEPON overlaid on top of an RF-PON build provides an opportunity to sell optical Ethernet transport and advanced services with a lower activation cost than traditional optical Ethernet. Properly engineered, RF-PON and GEPON can exist on the same PON investment supporting the current video, data and voice product portfolio.
“We are reviewing ‘cable-centric’ GEPON technology opportunities for 2010 deployment. GEPON solutions must support both the current triple-play ecosystem and support cable back office provisioning architectures.”
|Aurora's analysis assumes a 65
percent service penetration in
A = Aerial plant
U = Underground plant
Source: Aurora Networks
|HD (high density) refers to plant with 200+ homes passed per mile
MD (mid density) includes densities of about 80 homes per mile
LD (low density) is typically 25 to 30 homes passed per mile
FIBER DEEP STILL THRIVING
Compared with the other fiber technologies, Fiber Deep is a grizzled veteran. Suddenlink Communications first deployed a Fiber Deep solution in Malvern, Ark., nine years ago. Since then, Suddenlink has rolled Fiber Deep into some of its largest markets as part of its $350 million capital investment plan that is slated to be finished by 2012.
Aurora Networks has been successful in deploying Fiber Deep, and Dahlquist said it’s especially good for brownfield deployments.
“With Fiber Deep, you get a tremendous amount of operating benefits,” he said. “You cut your power bills by 50 percent. You have no seasonal sweep and balance because you have no amplifiers. The number of active devices in your system is now typically 25 percent to 35 percent less than what it used to be, so the reliability of the network goes up, as well.”
Dahlquist said DOCSIS 3.0 upstream channel bonding would also lead to more Fiber Deep deployments this year, as well as an overall increase in the demand for bandwidth.
Over the past three years, Cox has been laying dark fiber in new builds in order to “future-proof” its design. The dark fiber could be used for greenfield deployments or commercial services today, but the main point is that Cox is pushing fiber deeper into the neighborhoods it serves.
“What we call Fiber Deep is we overlay dark fiber with the coax deeper toward the premises, so even though fiber stops today and turns into coax at the edge of the neighborhood, we build dark fiber into the neighborhood for future use,” Civiletto said.
In a similar vein, Shaw is adding extra conduit on its new builds in order to pull fiber through down the road.
“It’s obviously not reasonable to retrofit with fiber where we have direct, buried coax, but we’ve been planning this for some time,” Steiger said. “The pricing has gotten to the point where it makes sense to go with fiber. It’s exciting for our cable plant guys because we think this fiscal year is the last one where Shaw will be building all new plant with coax. It’s really a transitional year for us.”