AT&T and its Open radio access network (RAN) partners Ericsson and Fujitsu’s 1Finity division hit an important connection milestone that further paves the carrier’s multi-year and multibillion-dollar network upgrade program.

The trio connected a call using third-party radios at AT&T Labs. That call ran over Ericsson’s 6672 baseband RAN processor and 1Finity radios.

The test builds on AT&T’s ambitious Open RAN push announced in late 2023. That announcement called for the carrier to spend around $14 billion over a five-year period to deploy Open RAN equipment with the goal of having 70 percent of its wireless network traffic flowing through its Open RAN platform by the end of 2026.

That initial announcement included a somewhat controversial decision to rely on Ericsson for the basis of the deployment, as the vendor had at that time not been viewed as a proponent of Open RAN technology. However, the vendor has since bolstered its Open RAN work and has a long history of working within AT&T’s network architecture.

Ericsson is providing its Intelligent Automation Platform (EIAP), which is the vendor’s service management and orchestration (SMO) platform. The EIAP will span across multiple domains, including the service level where it can control the cloud RAN and traditional RAN functions, the radios, and the hardware.

Fujitsu was also named as the initial Open RAN vendor to the program, with a focus on deploying its Open RAN equipment running on top of the Ericsson platform. Fujitsu has gained considerable Open RAN opportunities from its ongoing work with operators like NTT DoCoMo, KDDI, and Boost Mobile in the U.S., and it has an optical networking legacy with AT&T.

Fujitsu recently formed its 1Finity operating company to oversee network-related operations. This includes the legacy Fujitsu Telecom Networks, Fujitsu Network Service Engineering, Mobile Techno, and Fujitsu Network Communications.

AT&T late last year provided more color on the depth of that collaboration by noting the Fujitsu radios were designed with a lower profile that can be attached to existing utility and light poles in dense, urban environments.

Radio specifics include the supply of open C-band (3.7 GHz-4.2 GHz) radios supporting time-division duplex (TDD) with four-transmit and four-receive antennas (4T4R), and dual-band radios supporting band 25 (1.9 GHz-2 GHz) and band 66 (1.7 GHz-2.1 GHz) with frequency division duplex (FDD) 4T4R antennas. FDD spectrum is typically fixed in splitting its channel capacity evenly between the uplink and downlink, while TDD technology allows operators to adjust the uplink and downlink capacity of a spectrum channel based on need.

Open RAN multivendor challenge

The multivendor success is an increasingly important challenge for Open RAN deployments.

Verizon last year announced it had successfully launched a multivendor Open RAN distributed antenna system (DAS) at the University of Texas in Austin and the Austin Convention Center using equipment from Samsung and CommScope running on top of the carrier’s Edge-focused virtualized cloud architecture.

“Not just having one vendor with both the baseband and the radio being O-RAN compliant, but mixing and matching those and having a vendor for the baseband and a vendor for the radio, and they’re two separate vendors, that is really the most challenging aspect of O-RAN but it’s one that yields the most long-term benefit,” Adam Koeppe, SVP of technology planning at Verizon, explained to SDxCentral at that time.

That notion was backed by Boost Mobile CTO Eben Albertyn, who, during a recent trade show, touted open RAN interoperability progress. This was on the back of the carrier’s unique open-architecture based 5G network that it’s using in an attempt to be a No. 4 player in the competitive US market.

“The perception that I pick up sometimes when I speak to the industry is that open RAN is not mature,” Albertyn said. “As I've explained, the other three have been optimizing that network for about 30 years now. We've been at it for about a year and a half, and we've beaten them on quality in the biggest city in the world, in New York City. So Open RAN is real, and it's not as technical as people think. It's a very mature technology.”

Albertyn did admit that Boost Mobile struggled through the initial deployment, hindered by it being one of the first in the world to push a greenfield cloud-native deployment. But the move has allowed the carrier to be more aggressive in vendor management.

“I think Open RAN and the technologies that we’ve used goes far and beyond just that of the radio; it changes the entire way of interacting with your supply chain and your landscape, and there is a lot more control that allows you to manipulate cost and quality in a way that suits your situation,” Albertyn said. “We didn’t want to go through all of these pains. We didn’t want to go through these changes, but we were, I think, extremely grateful that we had the opportunity to change at will when you’re in the situation changed.”

Despite the progress, not all are fully ready to sign off on open RAN.

Analysys Mason, in a recent operator survey, found ongoing concerns over deeper levels of Open RAN complexity. Specifically, the analyst firm found one-third of operators think Open RAN will make security management harder, though it should also be noted that another one-third of respondents expressed the opposite opinion.

“Such contradicting opinions about open RAN security are common,” James Kirby, senior analyst at Analysys Mason, wrote. “For example, some pundits claim that the increased number of open interfaces will pose a considerable security challenge, while others argue that proprietary interfaces are not necessarily more secure and that the greater visibility into Open RAN architectures makes vulnerabilities and threats easier to spot. Given that security failings can lead to hefty fines and reputational damage for operators, this uncertainty is contributing to slowed Open RAN adoption.”

Kirby added that it’s imperative for the industry to work on better Open RAN security standardization in order to alleviate concerns.

“To drive progress toward widespread, at-scale commercial adoption of multi-vendor open RAN (and support ecosystem diversity), it is imperative that progress is made to build confidence in its security and reduce its related operational burden,” Kirby states. “Critically, the industry must advance standardization with a goal to reach recognized security certifications that can create consistency in the ecosystem and de-risk and reduce the burden of multi-vendor security for operators.”