AT&T fiber field trial pumps out 20-Gig symmetrical speeds

Demonstrating that 25GS-PON technology has taken another step toward commercial reality, AT&T said it has successfully delivered symmetrical speeds of 20 Gbit/s on its production network.

The trial, helmed by Austin, Texas-based AT&T Labs, was conducted in nearby Pflugerville, and it was run over about five miles of fiber extending from the central office (CO). The CO element tapped into tech from Nokia powered by the vendor's Quillion chipset in tandem with customer premises equipment (CPE) outfitted with field-programmable gate arrays (FPGAs), according to Eddy Barker, AT&T's assistant VP of mobility and access architecture.

Future CPE for 25GS-PON will run on SoCs (systems-on-a-chip), a move that will support much broader scale and lower costs, he explained.

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(Source: Roman Tiraspolsky/Alamy Stock Photo)

Barker noted that thousands of customers are served off the CO location used for the trial, and a subset of them, including select stores and work center locations, were involved in the trial itself.

The test, run on a shared point-to-multipoint architecture, was conducted with customers that were already getting "hyper-Gig" speeds from AT&T, including the telco's recently launched 2-Gig and 5-Gig fiber-based services. AT&T used "FiberWise," the company's name for wavelength division multiplexing (WDM), to overlay the speedy test wavelengths on existing fiber.

That approach allows AT&T to put multiple technologies on the same piece of glass. Barker said the trial demonstrates that AT&T can put XGS-PON (the tech it's using today to deliver multi-gig speeds on fiber) and 25-Gig PON on the same exact fiber and also pursue a future path to possibly do the same with 50-Gig and 100-Gig PON.

According to Barker, commercial readiness for 25-Gig PON isn't far away, as he expects early adopters to go to market with it around late 2023 and into 2024. He also expects business services to be among the initial use cases for 25-Gig capacities as bandwidth-intensive apps – such as extended realities, the so-called metaverse and new telemedicine offerings – continue to take shape.

"I think you'll gradually see the app developers come on board with applications and resolutions and real-time capabilities that can exploit these higher speeds," Barker said.

What's next?

On the supplier end, Nokia is expected to be joined by others with respect to the CO side of the network, with more CPE chipset development to follow.

"I think that's the last piece to finalize the maturity of the ecosystem," Barker said of the CPE component for 25GS-PON. "Hopefully, we'll see that later this year, and we get more diversity in that area in 2023. At that point, it becomes pretty solid as an ecosystem perspective in order to be able to develop it and deploy it."

On the CO end, AT&T is already using XGS-PON gear based on Nokia's Quillion chip.

"That same exact card with this silicon in it can support this technology ... The fiber is all exactly the same," Barker said.

This latest test follows one conducted earlier this year in which AT&T tested symmetrical 10-Gig speeds in its labs. AT&T's recent battery of fiber-fueled speed tests push its cable rivals to accelerate plans for DOCSIS 4.0 for their widely deployed hybrid fiber/coax (HFC) networks or to pursue fiber-to-the-premises (FTTP) upgrades more heavily.

All of AT&T's trial activity is coming together as the company continues to push ahead with a fiber buildout plan targeting 30 million households and businesses by 2025.

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— Jeff Baumgartner, Senior Editor, Light Reading