Open RAN involves the interoperability of open hardware, software and interfaces introducing advanced features and capabilities beyond the current standard centralized approaches to the RAN through leveraging a programmable open-software development approach.
Open RAN interfaces can allow for a “disaggregated” RAN into functional components such as a Radio Unit (RU), Distributed Unit (DU), Centralized Unit (CU) to facilitate an open user plane, control plane, synchronization plane as well as management plane.
Open RAN disaggregates the RAN into main 3 components as below:
-Central Unit (CU) which is logical node that includes a portion of the eNB/gNB functions as defined by split option 2. It includes RRC, SDAP and PDCP.
-Distributed Unit (DU) which is Logical node that includes a portion of the eNB/gNB functions as defined by split option 7-2x. O-DU controls the operation of a number of O-RUs and includes RLC, MAC and high Physical Layer.
-O-RAN Radio Unit (RU) which is Physical node that includes a portion of the eNB/gNB functions as defined by split option 7-2x. It is controlled by the O-DU and contains Low physical layer and RF.