Cable Technology Feature Article
EPoC is a Strong Contender for Next-generation Broadband Cable
By Joan Engebretson, Contributing Editor
The DOCSIS 3.0 standard seems to have a lot of life left in it. But that isn’t stopping the cable TV industry from thinking seriously about the next generation of broadband cable technology.
One of the options that the cable industry is eyeing most seriously is Ethernet PON over coax (EPoC), an emerging technology option that would enable cable operators to support Ethernet passive optical network technology over a combination of fiber and coax. EPoC was a hot topic at last week’s plenary session of the IEEE (News - Alert) 802 LAN/MAN standards committee, according to Howard Frazier, who is senior technology director for Broadcom as well as chairman of the IEEE 802.3 EPoC PHY study group.
Frazier gave TMCNet the rundown on EPoC standardization efforts on a phone call from Honolulu, where the plenary session was held.
As he explained, cable operators see EPoC as a great way of meeting their goal of “getting as much money as possible out of every tiny increment of” coaxial spectrum.
“They really like the cost model of Ethernet and EPON,” he said.
The EPoC PHY study group just had its second meeting and as of now Frazier said the group has outlined what it would like to accomplish with EPoC, such as ensuring that EPoC is compatible with other standard uses of cable company coax. The study group phase is expected to be completed by July, with authorization obtained by September, when formal work on creating the standard would begin.
I asked Frazier how EPoC would impact cable network architecture and he gave me an idea of what the group is thinking about—although he emphasized that nothing has been formally determined yet and that any thinking about network architecture is speculative at this time.
With that caveat in mind, Frazier said the EPoC standard is likely to target a speed of at least 1 Gbps to the home, although bandwidth might be lower in certain circumstances, such as when the coaxial cable is impaired or only a limited amount of spectrum is available.
To support high speeds over EPoC, cable operators are expected to bring fiber deeper into the network. “The desire is to serve around 500 homes per fiber drop,” Frazier said.
Because operators could use amplifiers to boost the signal, Frazier said the distance between the home and the fiber drop could be substantial. Some people are talking about support for up to five cascaded amplifiers from the fiber node, he said.
Frazier estimated that cable operators would need about 120 MHz of spectrum or the equivalent of about 20 television channels to meet the 1 Gbps speed target, but also noted that the exact number could vary depending on the type of modulation used. Frazier added that cable operators want the flexibility to put EPoC wherever they want to in the spectrum band.
Whatever final form the EPoC standard takes, it is likely to include both a symmetrical and an asymmetrical version—and service providers likely will want to be able to separately provision the upstream and downstream paths, Frazier said.
Interest in EPoC is particularly strong in China, Frazier said. But he also noted that North American service providers were well represented in last week’s activities and he saw strong interest in the technology from them as well.
Edited by Jennifer Russell