Explaining Open RAN

If you read more than an article or two about 5G and cellular technology you’re likely to run across the term Open RAN. You’re likely to get a sense that this is a good thing, but unless you understand cellular networks the term probably means little else. Open RAN is a movement within the cellular industry to design cellular networks using generic equipment modules so that networks can be divorced from proprietary technologies and can be controlled by software. This is akin to what has happened in big data centers where software now controls generic servers.

The first step in creating Open RAN has been to break the network down into specific functions to allow for the development of generic hardware. Today’s cellular networks have two major components – the core network and the radio access network (RAN). The easiest analog of the core network is to think of it the same as a tandem switching center. Cellular carriers have regional hubs where a set of electronics and switching process the traffic from large numbers of cell sites. The RAN is all of the cell sites where the cellular company maintains a tower and radios to communicate with customers.

Open RAN has broken the cell network into three generic modules. The radio unit (RU) is located near to or is incorporated into the antenna and is the electronics that transmits and receives signals from customers. The distributed unit (DU) is the brains at cell sites. The centralized unit (CU) is a more generic set of core hardware that communicates between the core and the distributed units.

The next step in developing Open RAN has been to ‘open’ the protocols and interfaces between the components of the cellular network. The industry has created the O-RAN Alliance that has developed open-source software that controls all aspects of the cellular network. The software has been developed in eleven generic modules that handle the major functions of the cellular network, For example, there is a software model for controlling the front-haul function between the radio unit and the distributed unit, a module for the mid-haul function between the distributed unit and the centralized unit, etc.

While the industry has created generic open-source software, each large carrier will create their own flavor of the software to configure features the way they want them. Today it’s hard to tell the difference between using AT&T versus T-Mobile, but that is likely to change over time as each carrier develops its own flavor of features.

There are some huge benefits to an Open RAN network. The first is savings on hardware. It’s far less expensive to buy generic radios rather than proprietary radio systems from one of the major vendors. In data centers, we’ve seen the cost of generic switches and servers drop hardware costs by as much as 80%.

But the biggest benefit of Open RAN is the ability to control cell sites with a single software system. Today, the task of updating cell sites to a new feature is a mind-boggling task if the upgrade requires any hardware. That requires a technician to visit every cell site in a nationwide network. Even software upgrades are a challenge and often have to be done today on site since there are numerous configurations of cell sites in a network. With Open RAN, features would be fully software-driven and could all be updated at the same time.

The cellular carriers love the concept because Open RAN frees them to develop unique solutions for customers that are software-driven and not limited by proprietary hardware and software. The industry has always talked about developing specialized features for industries like agriculture or hospitals and Open RAN provides the platform to finally do that. Even better, each major hospital chain could have unique features it desires. This leads to an exciting future where customers can help design their own features rather than accept from a menu of industry features.

Interestingly, the Open RAN concept will also carry over into cellphones, where the best cellphones will have generic chips that can be updated to develop new features without having to upgrade phones every few years.

Converting to Open RAN won’t be cheap or easy because it will ultimately mean scrapping most of the electronics and software being used today at every cell site. We’re likely to first see the big carriers breaking in Open RAN by segments, such as using the solution for small cell sites before converting the big tower sites.

One cellular carrier is likely to take the lead in this movement. Dish Networks is in the process of building a nationwide cellular network from scratch and the company has fully embraced Open RAN. This will put pressure on the other carriers to catch up if Dish’s nimble network starts capturing large nationwide customers.

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