Section: 4.3.2.1 Common MR-DC principles
Content: There are different U-plane connectivity options of the MN and SN involved in MR-DC for a certain UE, as shown in Figure 4.3.2.1-1. The U-plane connectivity depends on the bearer option configured: - For MN terminated bearers, the user plane connection to the CN entity is terminated in the MN; - For SN terminated bearers, the user plane connection to the CN entity is terminated in the SN; - The transport of user plane data over the Uu either involves MCG or SCG radio resources or both: - For MCG bearers, only MCG radio resources are involved; - For SCG bearers, only SCG radio resources are involved; - For split bearers, both MCG and SCG radio resources are involved. - For split bearers, MN terminated SCG bearers and SN terminated MCG bearers, PDCP data is transferred between the MN and the SN via the MN-SN user plane interface. Figure 4.3.2.1-1: U-Plane connectivity for EN-DC (left) and MR-DC with 5GC (right).