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CCAP’s Remote Possibilities

Now that cable has moved forward with deployments of centralized, fully-integrated Converged Cable Access Platforms (CCAPs) that pack the cable-modem termination system and the edge QAM into one chassis, it’s only natural that some vendors are starting to unleash products that take a decentralized route and push those functions to the far edges of the cable network.

The latest vendor to join the mix is Harmonic, which has introduced the NSG Exo, a distributed form of a CCAP that complements its NSG Pro, a chassis-based CCAP designed to be installed at the operator’s hub or headend.

Harmonic is taking a different tack with each product. The NSG Exo is starting off as a CMTS that will add edge QAM functionality through a future software upgrade, while the NSG Pro is doing just the opposite — starting life as a super-dense edge QAM, with CMTS and upstream components to be tacked on later.

“We support CMTS out of the chute, and while the hardware supports the eQAM functionality, the software will be available in the future,” Asaf Matatyaou, Harmonic’s director of cable edge solutions, said.


The compact NSG Exo, due out in the third quarter of 2014, will be Harmonic’s first commercially available CMTS. The first iteration will be tailored for indoor deployments, with an outdoor unit slated for launch sometime later this year. Harmonic has multiple trials underway with operators “across regions,” Matatyaou said.

Harmonic believes this dual-product approach with CCAP will address a broader range of access architectures, allowing for deployments that require highly-centralized CCAPs that serve individual homes and subscribers, as well as more distributed forms that are well-suited for businesses, hotels, college campuses and apartment buildings, Matatyaou said.

Boiled down, Harmonic is billing the NSG Exo as a lowpower yet dense device that shifts the radio-frequency components from the headend or hub to the edges of the operator’s network. It takes digital fiber in and outputs DOCSIS, MPEG-based video and other RF-based services.

An NSG Exo can support in the range of 250 to 500 customers, Matatyaou said, noting that the distributed architecture of the product has the potential to serve not just traditional cable operators, but also telcos that terminate fiber to multiple dwelling units but still need to run services on in-building coax-based networks.

With the NSG Exo, Harmonic is the latest vendor to bring forth a distributed form of a CCAP-based product, though different schools of thought are emerging. Cisco Systems, for example, is pursuing a similar idea that deploys physical layer (PHY) elements remotely, but keeps DOCSIS processing in the hub.

Gainspeed, a startup, is developing a software- controlled “virtual” CCAP with Juniper Networks and other technology partners that aims to distribute both the media access controller (MAC) and PHY, with some processing for DOCSIS and MPEG still occurring in the hub. Arris has also revealed that it has a virtual CCAP on its roadmap. Aurora Networks, now part of U.K.-based set-top giant Pace, has developed a distributed device called the Node QAM.


“There’s tremendous momentum around remote, distributed solutions,” Jeff Heynen, principal analyst for broadband access and pay TV at Infonetics Research, said, noting that this emerging architecture, which keeps signals in digital form deeper into the network, can put cable operators in better position to support the higher modulations envisioned for DOCSIS 3.1, a CableLabs spec that will pave the way for speeds up to 10 Gigabits per second downstream and at least 1 Gbps in the upstream.

“That part of the transition is clear,” he said, but he doesn’t foresee distributed CCAPs completely cannibalizing the market for today’s integrated CCAPs.

Still, he thinks distributed CCAPs will also come in handy in just about all markets, including China, Europe and South America, where operators are looking to push broadband services to apartments and other high-density environments that are tailor-made for fiber-to-thebuilding architectures.

And it’s not just the usual suspects that are getting involved. In addition to the traditional cable suppliers, “dozens” of vendors in China, including Huawei and ZTE, have developed products that fit the distributed CCAP profile, Heynen said.