AT&T recently announced a $14 billion dollar deal with Ericsson to start upgrading its cellular networks to Open RAN (ORAN). I suspect most of the readers of this blog know a lot more about fiber technology than cellular technology. They’ve probably been seeing headlines for years talking about various flavors of RAN technology and probably wondered what it means. The bottom line is that the AT&T announcement is a big deal and means a big shift in the cellular vendor industry.

RAN stands for Radio Access Network, which is an acronym for the radios and antennas at a cell site. Open RAN represents a migration to a software-driven network where any brand of radio can be used at a cell site. This is a big deal in an industry where three major companies – Huawei, Ericsson, and Nokia – have made the gear for cellular networks. This means that most cellular networks rely entirely on the proprietary gear of a single vendor. A shift to Open Ran is akin to the migration a few years ago when data centers migrated to lower-cost white box routers and switches instead of having to buy proprietary gear from large vendors like Cisco.

However, the migration of the cellular network to generic hardware is a lot more complicated than making switches operate in a data center. This is mostly due to the complicated nature of operating a cell site in an environment where factors like temperature, precipitation, and customer traffic volume change the overall performance and operating characteristics of a cell site during the day. I always think of the old saying that operating a fiber network is science while operating a wireless network is art. The only solution for dealing with the complexities found at cell sites has been to pick an integrated suite of products from one vendor.

AT&T is the largest cellular carrier to announce it is moving towards ORAN. A few years ago, the newly formed DISH cellular effort announced it would use ORAN, but the technology was not ready, which drastically hindered the company’s initial launch of the network. The UK announced in 2021 that it has a goal to migrate its cellular networks to 35% Open RAN by 2030. The AT&T announcement doesn’t mean the company will be able to freely integrate any brand of radios into its networks but is a big first step towards true Open RAN.

The original view of Open RAN was that a cellular company could put any radio anywhere, connect it to the backhaul, and it would work. The software in the cloud would automatically handle the integration with the overall network and the surrounding cell sites, and the new site would work out of the box.

We’re still a long way from that ideal and may never fully get there. Cellular carriers have relied on the major vendors because they made sure that a cell site would work. I think back to all of the other launches of wireless technology where vendors released beta equipment and the first generation of customers were, unfortunately, the guinea pigs. I painfully recall watching ISPs try to launch wireless broadband networks using LMDS and MMDS spectrum and failing when the radios didn’t operate as promised.

Part of the reason that the migration to Open Ran has been slow is that vendors and carriers have also been pursuing other network options to cut costs. Historically, all of the electronics were fully integrated at a cell site. The RAN radio units were installed on a tower, and the BaseBand unit (BBU) with all of the brains was installed in a hut at the base of each tower. Technicians had to go through the time-consuming process of fine-tuning the electronics at each tower to meet the specific local circumstances.

In recent years, there have been efforts to consolidate some of the BaseBand Unit functions.

• DRAN (Distributed RAN) was the first attempt to separate the base electronics from the radios. That was a lot harder than it might seem because a cellular tower relies on precise timing and fiddling with the type or length of wiring between the radios and the base caused all sort of problems.
• CRAN (concentrated RAN) moved the base units into regional data centers (BBU hotels) and opened up the concept of DAS – Distributed Antenna Systems that would work from these centralized sites.
• C-RAN (Cloud RAN), not to be confused with CRAN, has been a movement to move the entire brains of a cell site into data centers.

Open RAN takes something from each of these various evolutions and takes the final step of breaking the equipment monopoly of the big vendors. This isn’t going to be easy and has the danger of moving back to a time when we test new radios by foisting them on the public. But the savings from ORAN are potentially gigantic, and if we’ve seen anything in the wireless industry, it’s that the lowest-cost option is going to get the most attention.