AT&T lays C-RAN foundation in preparation for 5G

AT&T (Wikipedia)
AT&T's small cells use a Centralized RAN, or C-RAN, architecture, which means the "brains" of each small cell or tower exist in one location. Image: Wikipedia

As one might expect, AT&T is deploying its centralized RAN (C-RAN) architecture first in places where it makes sense: where traffic density is the highest.

AT&T revealed earlier this year that it had started deploying small cells using C-RAN architecture in San Francisco. That deployment is being replicated in other cities, enabling the operator to densify its network and lay the groundwork for 5G.

AT&T’s definition of C-RAN is centralized RAN. C-RAN can also stand for Cloud-RAN, which is often used interchangeably with Virtualized RAN, or V-RAN. AT&T plans to get to V-RAN, but first it needs to centralize things.

Gordon Mansfield, vice president, RAN and Device Design at AT&T, explained that how AT&T decides to deploy C-RAN is based on where traffic density is the highest. When there are high amounts of video or other data traffic in the network, that requires densification and as it densifies, it's building those layers in a centralized way.

“The main reason is it helps us to shift the topology to prepare for millimeter wave and 5G capabilities that will follow,” he told FierceWirelessTech. “We’re doing a lot of proof-of-concept work in the virtualized space,” he said. “As we move to 5G, I would expect we’ll begin to virtualize a lot of the components that are at our centralized locations.”

Certainly there are places where implementing C-RAN is difficult, but that just takes more time to overcome; it’s not as if it plans to waive those locations. “You prioritize the places where it’s easier,” he said.

RELATED: For AT&T, more C-RAN is in the clouds

It’s all related to AT&T’s march to virtualize its network, which includes SDN and NFV. The mobile core already has software-defined capabilities as part of the company’s previously announced 34% of functions virtualized last year and the 55% goal for this year. “A lot of the mobile core components have been virtualized already,” he noted.

Last year, AT&T introduced ECOMP, which helped it achieve its virtualization goals. In February, The Linux Foundation announced the merger of ECOMP and The Linux Foundation’s open source networking project called Open-O to form ONAP, bringing two of the largest open source platforms together.

Service providers representing 55% of global wireless subscribers have officially committed to the ONAP platform, and AT&T says there are many more in the pipeline.