DENVER – Looking towards the future, two cable industry standards groups have adopted two different sets of technical specifications aimed at spurring the industry’s deployment of all-fibre networks.
In late December, the Society of Cable Telecommunications Engineers (SCTE) finally approved its Radio Frequency over Glass (RFoG) standard after more than two years of discussion and sometimes testy technical debates. The new RFoG specs enable cable operators to extend fibre lines all the way to homes and businesses without needing to switch out their existing headends, back-office systems, set-top boxes, cable modems, or other equipment. As a result, MSOs now have a standard way to deploy fibre-to-the-premises (FTTP) networks and deliver their services to subscribers.
Following SCTE’s lead, CableLabs then approved its DOCSIS Provisioning over EPON (DPoE) specs late last month after a much shorter deliberation process. This new set of eight specs provides a common way for cable operators to use DOCSIS provisioning and back-office systems for EPON support. With DPoE now in place, MSOs will be able to deploy Ethernet Passive Optical Network (EPON) technology over fibre lines, just like telcos.
Taken together, these twin moves should make it easier for North American cable operators to deliver multimedia services to their subscribers over FTTP networks. Such a fibre-driven strategy seems critical as MSOs increasingly compete with ambitious fibre builds by such leading telcos as Verizon Communications and AT&T in the U.S. and Bell Canada, Telus, Bell Aliant, and others here in Canada.
Although U.S. and Canadian cable providers have built a few fibre extensions in smaller markets and limited settings over the past couple of years, they have generally shied away from deploying full-fledged FTTP networks. But that’s now beginning to change as major MSOs like Shaw Communications begin to experiment with building FTTP networks in new markets and new sections of existing markets. (Some smaller operators, like Source Cable, are also going fibre builds to new markets.)
The RFoG standard, now labeled SCTE 174, eliminates electrical amplifiers, thereby cutting power costs significantly and giving cable operators a much "cleaner" plant. But it doesn’t provide MSOs with much of an immediate capacity boost, even though the architecture does allow for passive optical network (PON) overlays.
As a result, cable operators and equipment vendors view the standard as more of a niche play for the industry right now. With the new-housing construction industry still deeply depressed, they see MSOs mainly using RFoG for greenfield deployments, rural plant extensions, and business service connections, not the new housing developments that were originally contemplated.
Nevertheless, vendors say, RFoG is starting to curry favor with cable operators seeking to bridge to PON technology. For instance, they say, independent operators are beginning to use RFoG in conjunction with PON while relying on an RF overlay for video services.
With the standard now heading to the American National Standards Institute (ANSI) for further approvals, the International Electrotechnical Commission (IEC) committee for audio, video and multimedia systems and equipment is contemplating incorporating RFoG into its IEC 60728 international cable standard. The committee is expected to consider that action at its mid-May meeting in Germany.
Plus, SCTE is already starting work on a second generation of RFoG. In January, the group’s engineering committee approved a follow-up project to consider such enhancements to the standard as Multimedia over Coax Alliance (MoCA) interoperability and remote monitoring and management for RFoG optical network units (ONUs).
Turning to the new CableLabs standard, DPoE is designed mainly to help cable operators deliver commercial-class IP and Ethernet services to business customers over fibre networks. But, industry analysts say, DPoE could also be used to spur the delivery of residential cable services over fibre lines someday.
Speaking at a Light Reading conference on cable next-gen broadband strategies in Denver late last month, Curtis Knittle, director of digital video services for CableLabs, said the industry R&D group successfully staged its first equipment interoperability testing for the new specs in late January. About 10 vendors participated in the week-long testing event, including such major gear suppliers as Broadcom, Cisco Systems, Hitachi, Huawei, and ZTE.
Knittle said CableLabs plans to hold three other interop testing events this year, with the next one slated for mid-April. In addition, CableLabs has already started working on a second-generation version of the specs, which it hopes to complete next fall.
Alan Breznick is a Toronto-based senior analyst at Heavy Reading, part of the Light Reading Communications Network.
