According to John Baker, senior vice president of business development at Mavenir, there is still considerable ambiguity surrounding the definition of Open RAN. In an effort to clarify the situation, he attended the 2022 Open RAN Global Forum, where he spoke about the three essential RAN transformations that are emerging: open fronthaul, disaggregated Open vRAN, and Open Ran in the cloud.
“Open RAN is only about the interfaces between the elements; it is not about the interfaces within the products … The ecosystem at this point has not gotten into defining the open interfaces within the product,” he elaborated, explaining that the deployment of Open RAN in different environments and the placement of the Distributed Unit (DU) and Centralized Unit (CU) in different locations within the network will introduce new and distinct use cases.
1. Open fronthaul
In an open fronthaul model, a virtual baseband unit (vBBU) and non-Open RAN hardware are connected to a 3GPP-specified backhaul. Baker does not believe that this will be the predominant model in the future. “You can implement Open RAN in hardware [or] software, but the ecosystem is certainly moving towards a software implementation of the RAN going forward,” he said.
2. Disaggregated Open vRAN
In the disaggregated Open vRAN model, base stations are divided into various functional units, thereby facilitating the interfaces between disaggregated hardware and software. “In this architecture, you have open fronthaul … the virtual DU … then the virtual CU, which can be centralized in data center-type applications hundreds of kilometers away,” Baker stated.
3. Open RAN in the cloud
According to Baker, the final architecture is Open RAN in the cloud, where the DU does not need to be at the cell site, and this is where true network cost optimization can be realized. “The site real estate … tends to be expensive,” he said, adding that installing DUs at every cell site is an expensive architectural strategy. Nevertheless, he continued, in the Open RAN in the cloud model, a provider can “pool” multiple cell sites on a single DU located between the sites at the data center.
“As soon as you can start pooling to a single DU, that’s really where the … effects of running multi-versions of software on a single compute function actually begins. This is where you start the true cost benefits of Open RAN in terms of the architecture.”
In this model, midhaul can also be used to locate CUs in data centers, thereby increasing the flexibility of network architecture. “We have already seen this with Dish announcement where the CUs are actually hosted in the Amazon cloud,” said Baker.
In addition to network flexibility, the cloud-based approach enables operators to choose the best vendors, rapidly deploy service when and where it is required, adds network resilience, and creates new revenue-generation opportunities.
Baker stated that Open RAN in the cloud is the model most likely to expedite the development of the 5G ecosystem. This is due to the fact that when the RAN is “running on the back of a huge network and system” — such as the AWS cloud — sites can be “deployed at almost the press of a button,” allowing operators to construct 5G networks at a much faster rate. In addition, with the CU and DU in the cloud, these elements can be easily tested for continuous innovation and enhancement.
“You can put out almost like experimental parameter variations on certain pieces of functionality of that RAN — multiple releases a day, continually upgrading and improving the network as you find that you need to make changes in it.”John Baker
Source: RCR Wireless