Verizon “Sets Stage” with Pre-standard XG-PON

Last week’s news of Verizon’s field test of 10 Gbps passive optical networking (PON) positions the company as a leader in a pre-standard technology that could be several years behind an alternative approach.

What the company tested was an implementation of XG-PON, a technology previously known as XG-PON1, which enables 10 Gbps downstream (DS) and 2.5 Gbps upstream (US). Originated in the Full Service Access Network (FSAN) group, XG-PON is now part of an ITU-Telecommunications Standardization Section (T) GPON project, with ratification expected in mid-to-late 2010.

According to Verizon, up until now this technology has been “tried only in demonstrations and lab trials.”

The trial involved a new optical line terminal (OLT) in a Verizon central office and a “test cart” in a customer’s house in Southern Massachusetts with optical network terminal (ONT) devices that could receive XG-PON and existing GPON signals. The results proved that Verizon could deliver these signals “on the same fiber at the two speeds, without any degradation in service.”

Verizon’s technology partner in this field demo—more trials with other vendors are “expected in the coming months”—was Huawei Technologies.
   
In its press release, the telecom giant twice referred to how this test “sets the stage” for meeting emerging consumer demand and offering increased speeds over its fiber-based network.

Trial, standards and apps

Physical layer coexistence was a primary theme of the trial.

“The test was mainly to see if (XG-PON) could coexist with current GPON technology, with the hopes and expectations that somewhere down the line, that bandwidth may be needed,” said Steve Nozik, principal analyst, broadband access, for the Dell’Oro Group.

Verizon began deploying FiOS in 2004 with Broadband (B) PON technology (622 Mbps DS/155 Mbps US) and introduced GPON (2.5 Gbps DS/1.2 Gbps US) several years later.

This trial was “proof of concept, and not to belittle that,” said Paul Runcy, director of the Americas and Europe for silicon developer Teknovus. “Verizon needs to be sure that this next-gen technology is going to work over the same plant that they’re already using.”

Teknovus manufactures components that implement the 10-G EPON standard (P802.3av), which the IEEE ratified in September 2009. Apart from the timing of the standard, 10-G EPON is distinct from XG-PON in several other respects.

The IEEE standard itself appears more extensive than its emerging ITU-T counterpart. Runcy said that 10-G EPON enables multiple DS and US speeds, not only over the same fiber and wavelength but also within the same PON domain. “GPON decided not to go that route,” he said.

Being ahead on standards has benefitted 10G-EPON operationally, as well.

“China Telecom has already done very extensive interoperability testing on both 10G symmetric and asymmetric,” Runcy said. “GPON is not at the point where a component company can make an ASIC or laser.”

Compared with 10-G EPON, Runcy said that in terms of a commercially viable interoperable specification, XG-PON was “two to three years behind.”

Verizon’s partner for this trial, Huawei, already has standing in this arena as a supplier to what Dell’Oro’s Nozik said was the world’s second largest (after Verizon) GPON deployment, that of Etisalat in the United Arab Emirates (UAE).

As for what applications might drive demand for a 10 Gbps residential service, the Verizon statement referred to “unicast HD video streaming, ultra-high-definition video, 3D video, user-generated content distribution, video conferencing and new high-speed data services for medium and large-business customers.”

For a related discussion of drivers addressed at last October’s FTTH Conference, click here.

For more from Dell’Oro on GPON and EPON market growth, click here.

—Jonathan Tombes