US mobile operators are generally open to exploring the potential of open RAN, but it's clearly evident that they are also wary of shortcomings that must be addressed before the emerging technology can be deemed ready for prime time. They definitely have toes in these open RAN waters, but aren't quite ready to take the Nestea plunge.

Verizon has said it expects to begin adding open RAN-compliant equipment into its network by the end of this year.

Meantime, T-Mobile's top networking executive has expressed serious reservations about the technology. "It's not ready for prime time for us," T-Mobile's Neville Ray said at an investor event late last year. "Today, I buy a solution from an Ericsson or a Nokia or a Samsung; it's warrantied. I have one neck to choke. If something goes wrong, I know where to go. In an O-RAN environment, you have to do a lot more heavy lifting as the operator."

Last week, in new comments to the FCC, both operators outlined their concerns about a technology that has so far been embraced by new market entrants like Japan's Rakuten and Dish Network in the US.

"While implementation of open RAN may ultimately be feasible in 'greenfield' deployments, deployment of open RAN in existing networks will be challenging," T-Mobile explained in its new FCC filing.

The operator continued: "Open RAN is not ready for full commercial deployment for several reasons. For example, methods must be developed for implementing regulatory mandates, like 911, across a multi-vendor environment."

Security concerns, technical challenges

T-Mobile specifically pointed to open RAN security, a topic that has generated plenty of debate among companies ranging from Ericsson to Dish Network. "In addition to recognizing the potential benefits of open RAN to network security, the commission should recognize that open RAN may, in fact, create security risks," T-Mobile argued. "Open networks are more prone to cyber security threats because they introduce additional interfaces, additional functions, and functional splits, which expand the surface for potential threats. The fact that open RAN relies on open source software increases the number of potential entry points for security breached."

Continued T-Mobile: "Moreover, there is no overall security assessment or requirement – whatever security mechanism exists are distributed and may not effectively flow through a network."

In its own filing, Verizon served up open RAN concerns as well.

"Access to Standards Essential Patents on Fair, Reasonable and Non-Discriminatory (FRAND) terms is another important factor as it will limit the uncertainty around intellectual property right infringement challenges that delay the development of new technologies such as open RAN," Verizon explained.

Verizon also briefly touched on some technological issues facing open RAN.

"Technical challenges generally relate to 5G wireless network-specific constraints that do not exist for traditional virtualized software deployments, such as extremely low latency requirements (potentially requiring workload-specific hardware accelerators), support for 5G-specific communication protocols rather than HTTP, energy efficiency, and security," the operator wrote.

Let open RAN run free of government interference

Despite such concerns, both Verizon and T-Mobile expressed support for broader open RAN principles regarding vendor diversity and open interfaces. "As T-Mobile has observed elsewhere, there can be benefits to open network architectures," the operator wrote. "They can, for instance, create a larger and more diverse product ecosystem, increase competition and reduce the over-reliance on any one vendor – particularly vendors that the US has found pose significant national security risks. They can also promote vendor diversity and potentially create price and feature competition."

Both operators also strongly urged regulators at the FCC to abstain from issuing mandates around the use of open RAN technology. The carriers strongly argued that the wireless market should be left to embrace or reject open RAN without government interference.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano