CU-CP and CU-UP separation

Splitting Control from Data

The Central Unit itself splits into two logical entities following the Control and User Plane Separation principle found throughout 5G. The CU-CP hosts RRC for signaling and the control-plane portion of PDCP, making it the brain that manages connections, mobility, and bearer setup. The CU-UP hosts SDAP for QoS flow mapping and the user-plane portion of PDCP, functioning as the data forwarding engine between the DU and the UPF. The E1 interface connects these two entities, carrying bearer context management messages that let the CU-CP instruct the CU-UP to create, modify, or release data…