NG-PON2 Explains Verizon's New Trunking and Access Architecture

Not since its decision to deploy fiber to the home for consumers, replacing its twisted-pair copper access media, has any single decision made by Verizon Communications likely been as consequential as its decision to deploy NG-PON2 networks using time and wavelength division multiplexing.

Bandwidth, by itself, is not the consequential implication, although NG-PON2 supports as much as 10 Gbps per account or location, and 40 Gbps per wavelength.

The big implication is the ability to logically separate wavelengths on a single optical fiber, and then dedicate wavelengths to end user accounts. Also, separate wavelengths can be used to deliver different services to different users (or support different applications) at a single location.

In principle, wavelengths also could be assigned to wholesale customers and can reuse existing optical fiber running GPON, which Verizon does, for the most part.

“Technologies such as NG-PON2 present exciting new opportunities for vendors, such as delivering residential and business services on multiple wavelengths over the same fiber,” said Vincent O’Byrne, Verizon director of technology.

In essence, NG-PON2 logically separates delivered bandwidth from physical media, to an extent. NG-PON2 also physically separates discrete wavelengths from each other, allowing discrete wavelengths to carry different services, with varying degrees of symmetry (upstream/downstream) and capacity.

In essence, what Verizon hopes to do is create a single physical trunking network that can support services for virtually any application or use case by using discrete wavelengths, and reusing much of the existing PON infrastructure.

What clearly is different now is a new set of applications beyond the fiber to home apps GPON was designed to support. The new use cases include fiber to the building for multiple-dwelling units, enterprise networking, mobile backhaul and fronthaul, as well as cloud-based radio access networks.

Supporters also believe operating costs will be as much as 30 percent lower than other alternatives, in part because expansion can be done incrementally, reusing passive investments to a large degree, and featuring relatively-modest upgrades of active components.

Those NG-PON2 features are behind Verizon’s new thinking on optical fiber deployment to support small cells, enterprise and consumer bandwidth requirements. One way of noting the change is to say Verizon hopes it no longer will build separate trunking networks for enterprise, mobile networks and residential and small business customers.

Instead, it hopes to deploy a single physical infrastructure, and then use separate wavelengths to deliver services (mobile backhaul, enterprise, small or medium business, consumer use cases).

NG-PON2 capabilities also are the reason Altice has decided to scrap the hybrid fiber coax access platform, alone among U.S. cable operators.

Researchers at CIR say $2 billion a year will be spend on 5G trunking infrastructure through 2022, with half the annual total spent in the United States.

Chinese service providers will spend more than $130 million on 5G backhaul in 2022. China will end up being the fastest-growing market for backhaul, CIR calculated, followed by South Korea.

“The technology that will dominate 5G backhaul will be NG-PON2,” CIR analysts predict. “By 2022, more than $890 million will be spent on this technology for 5G backhaul."

source: Nokia

The time and wave division multiplexing allows for higher bandwidth (up to 10 Gbps for any user with a total of 40 Gbps, going to 80 Gbps later) and optimal flexibility relative to bandwidth per user, fiber management, service convergence and resource sharing.

But capital expense also is expected to be 30 percent lower, with less operational complexity than dense wave division multiplexing, as well.

TWDM-PON offers up to four wavelength pairs (eight in the future) that can each be configured at different bitrates (10G/10G, 10G/2.5G, 2.5G/2.5G) to best address the specific requirements of residential, business, or backhaul services. Providing up to 10-Gbps symmetrical speeds on each wavelength.

The bottom line is that Verizon, and likely Altice, will be making the most-important change in distribution and access network design in decades.