with 5GC Similarly, the QoS aspects for MR-DC with 5GC follow the same principles that are applied in NG-RAN, which are described in Section 3.4 and defined in 3GPP TS 38.300. It is always up to the MN to decide whether a QoS flow for a given PDU session is handled by the MN or the SN. As a result, QoS flows belonging to the same PDU session may be handled by different nodes. This means that it may happen that, at the network side, a given PDU session may use two different SDAP entities: one at the MN and another at the SN, which is referred to as a split PDU session. For split PDU sessions, the MN requests the 5GC to establish two NG-U tunnel termina- tions at the NG-RAN side: one is to exchange user-plane traffic for a subset of the QoS flows of the PDU session handled by the SDAP entity at the MN and the other is to exchange user-plane traffic for the rest of the QoS flows of the PDU session handled by the SDAP entity at the SN. For QoS flows assigned to the SDAP entity in the SN, if the SN realizes that it cannot host a given QoS flow any longer, the SN can request the MN to remove the QoS flow from its SDAP entity. Also, if the MN realizes that it can host a given QoS flow previously assigned to the SDAP entity in the SN, the MN may inform the SN and remove the QoS flow from the SN's SDAP entity. Once a QoS flow is assigned to a SDAP entity, the node hosting SDAP entity can then decide how to map the QoS flow to an actual radio bearer, as well as its bearer type (MCG bearer, SCG bearer, or split bearer). In particular, if the SDAP entity for a given QoS flow is hosted by the MN and the MN decides that an SCG or a split bearer should be configured (in other words, SCG resources should be configured), the MN provides the relevant informa- tion to the SN: the DRB-level QoS parameters, the QoS flow to DRB mapping information, 4.3 Multi-Radio Dual Connectivity and the respective per-QoS flow information, based on which the SN configures appropriate SCG resources. On the other hand, if the MN decides the SDAP enti