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Cable Tech

DAA's benefits outweigh the challenges – panel

CABLE NEXT-GEN EUROPE DIGITAL SYMPOSIUM – With a pandemic-fueled capacity crunch now largely under control, cable operators are starting to rekindle next-gen projects, particularly around the distributed access architecture (DAA).

DAA, a requisite for future DOCSIS 4.0 networks, distributes key electronics toward the edges of the network that typically are contained in legacy, centralized Converged Cable Access Platform (CCAP) chassis.

The move, which could involve the distribution of the PHY layer of the network as well as the MAC layer, pulls fiber closer to the customer, digitizes the hybrid fiber/coax (HFC) network and beefs up overall performance.

But a primary advantage of DAA is the economics that underpin a new fiber-rich infrastructure, Kjeld Balmer, head of network technology at Danish network service provider Norlys/Stofa, an early champion of DAA, said last week here at an all-digital panel focused on the topic.

If the HFC plant is in decent condition with fiber connected relatively deep at the node, it's a pretty straightforward decision to pursue DAA rather than a more costly fiber-to-the-premises (FTTP) upgrade. "It's all about the economics" he said.

Those cost benefits extend to a significant reduction in headend sizes as well as the number of hubs required to serve certain geographies.

Headend and hub reductions derived from DAA can be "massive," said Anders Bloom, senior systems architect, broadband techops/broadband HFC, at Sweden's Tele2. Legacy CCAPs and cable modem termination systems "were great, but they were huge," he added.

Peter Wolff, VP of solutions architecture at with Casa Systems, a supplier of cable access network and DAA gear and software, said one of the vendor's cable operator customers was able to reduce the number of its hub sites from 32 to 13 with DAA, while another is in the process of shrinking 26 hub sites down to just two.

Colin Howlett, chief technology officer at Vecima Networks, said his company is seeing similar numbers, depending on the geography and population density of the given markets. "There is a significant reduction possible," he said.

And though a move to DAA can cut headend costs in the range of 30% or 40%, Balmer was quick to point out that some of those costs don't completely disappear from the map. For instance, a portion of the costs related to power consumption remain – they just tend to get pushed further out into the access network with DAA.

But shifting the network and the operations of the network to a DAA environment isn't without its challenges. Operators will need to adapt the video technology ecosystem to the DAA environment. They'll also need to prepared to handle a new mix of network maintenance issues that were not as prevalent as they were before DAA entered the picture.

Early on with DAA, it could take ten to 15 minutes for a remote PHY node to come back up during an outage, compared to a "matter of seconds" with a legacy node, Balmer said.

Vecima's Howlett noted that most field techs are used to plug-in nodes that recover quickly and, with DAA, are faced with getting a better fix on how the new configurations are done. But, once experience is gained and those challenges are overcome, operators are in position to take advantage of the agility and new capabilities that DAA allows through remote configurations.

But the monitoring of the video signal in a DAA environment "is quite challenging" even in the years following Stofa's initial deployments of DAA, Balmer said. "There are some issues we're facing, but in general it has been quite a smooth transition."

Bloom also acknowledged that relying on remote PHY devices to serve as the producer of the video signal presents "the big challenge" with the new architecture.

Though DAA is a requirement for future DOCSIS 4.0 networks, panelists agreed that DOCSIS 4.0 is not required to enjoy the full benefits of DAA.

"4.0 is more like the icing on the cake, so to speak," Bloom said.

And it appears that operators are all over the map on where they might want to head down the road. Some are interested in teaming DAA with DOCSIS 3.1, while others are asking for a specific upgrade path to DAA and DOCSIS 4.0, Wolff said.

DAA is also expected to help pave a path toward fixed wireless convergence thanks in part to the use of common digital transport for those services. "There's a big play for DAA in that journey," said Jeroen Putzeys, a VP of network sales at CommScope.

For more coverage of last week's all-digital event, hosted by Light Reading, please check out the following stories:

— Jeff Baumgartner, Senior Editor, Light Reading

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