In many networks, the RAN represents the last stronghold of proprietary hardware and software. While the mobile core is progressing to a virtualized, cloud-based architecture, the RAN remains rooted in vendor-based appliances such as the radio unit (RU) and baseband unit (BBU). In between these appliances, communications take place over proprietary protocols and interfaces based on vendor specifications rather than open industry standards. So, if you want to upgrade your RAN or increase its capacity, you need to return to the original vendor to add RUs and BBUs.
Open RAN disaggregates the BBU into distinct network functions — the centralized unit (CU) and distributed unit (DU) — that can be virtualized and deployed on standard COTS hardware. In addition, the CUs and DUs can be deployed locally or centrally, based on control- and user-plane traffic requirements, allowing mobile operators to scale intelligently as the number of devices and the amount of traffic scales independently. At the same time, Open RAN virtualizes the RU function for similar scaling and cost efficiency.