DENVER – With cable operators under mounting pressure to boost the capacity of their beleaguered networks and offer faster broadband speeds without overloading their headends and hubs with more costly equipment, the industry is now adopting a distributed access architecture (DAA) approach that will spread out the gear throughout their networks.
In particular, cable technologists are embracing a promising DAA option known as Remote PHY. Under this scheme, the physical layer (or PHY) of a traditional, dense cable headend CMTS or CCAP chassis is shifted to the fiber-optic nodes in the access network, allowing the data processing functions to occur there instead. Proponents say this approach will increase cable network capacity while also reducing power, cooling and headend and hub space requirements, lowering overall operating costs.
At the recent SCTE/ISBE Cable-Tec Expo show at the Colorado Convention Center here, nearly all the major cable equipment vendors showcased Remote PHY products for cable operators to try out and deploy. Arris, Casa Systems, Cisco Systems, Harmonic, Nokia and other manufacturers all promoted their Remote PHY nodes and related devices, which are upgraded, smarter versions of the current optical nodes that connect the fiber and coaxial cable segments of the networks and switch cable signals from light to electrical energy.
Meanwhile, CableLabs spelled out plans at the Cable-Tec Expo show to start testing the new breed of Remote PHY products to make sure they will all work in harmony with each other. Under this qualification program, which formally began October 1st, the cable industry's R&D alliance will certify that the Remote PHY (RPD) nodes and other devices from various vendors meet the same interoperability standards. Specifically, engineers will conduct the testing on two types of new network devices – the Remote PHY Node and the Remote PHY Shelf.
“We are open for business,” declared Jon Schmoor, distinguished technologist at CableLabs, during a special half-day seminar devoted to Remote PHY that drew an overflow crowd of more than 400 the day before the main conference began. Calling Remote PHY a “first step” for cable's next-gen access networks, Schmoor said Kyrio, a for-profit spinoff of CableLabs in Silicon Valley, is now accepting product submissions from vendors. He expects the new RPDs to start showing up for qualification testing by the end of the year.
"I don't know what we'll need the capacity for… I just know we'll need 50% more capacity next year." – Jorge Salinger, Comcast
In preparation for that official qualification testing phase, CableLabs has been staging Remote PHY "interop events" with equipment vendors and chipmakers. The R & D group has conducted nine such interop events with more than a dozen vendors so far, with a 10th event planned for later this month, according to Schmoor. Several major North American and European MSOs with a large Denver engineering presence, including Comcast, Cox Communications, Shaw Communications and Liberty Global, are assisting with this effort.
Also speaking at the Remote PHY seminar, Jorge Salinger, VP of Access Architecture for Comcast, emphasized that product interoperability between vendors will be critical for his company as it presses forward with lab and field trials and, shortly thereafter, commercial deployments of RPDs. If all goes well, Comcast plans to begin field trials later this year and move into commercial deployments sometime next year.
"I don't know what we'll need the capacity for," said Salinger, noting that Comcast is now scrambling to deploy DOCSIS 3.1 and offer gigabit speeds throughout the U.S. "I just know we'll need 50% more capacity next year."
Several other MSO executives outlined similar plans to start testing and deploying Remote PHY devices in their cable systems because of its potential cost and scale benefits. "We don't want to keep expanding sites," said Phil Oakley, Director of Access Platform Engineering at Liberty Global. He also cited the "fundamental flexibility" of the technology, which cable operators can roll out incrementally on a neighborhood-by-neighborhood basis if need be.
In an informal show of hands at the pre-conference workshop, about 10 other MSO officials indicated that they intend to roll out Remote PHY in 2018 as well. So Comcast and Liberty Global clearly won't be alone.
At the same time, CableLabs is racing to complete the remaining technical specifications needed for its new Remote PHY standard. Schnoor noted that there are now eight different specs for Remote PHY, including seven that are specific to it, along with an annex to a spec for the Downstream RF Interface (DRFI).
“We are desperately trying to finish the specifications,” he said. “But we want to make sure that we’re doing it right…The idea of remote PHY is simple, but the implementation and the design of it are very complex.”
