 the UE, via RRC signaling, with measurement configuration containing configurations of SSB/CSI resources and resource sets, as well as trigger states for trigger- ing channel and interference measurements and reports. Beam-level mobility is then man- aged at lower layers through physical layer and MAC sublayer control signaling. The RRC sublayer is not required to know about the beam that is used at any given time. The SSB- based beam-level mobility is based on the SSB associated with the initial DL BWP and can only be configured for the initial DL BWPs and for DL BWPs containing the SSB associ- ated with the initial DL BWP. For other DL BWPs the beam-level mobility can only be per- formed based on CSI-RS measurements [8]. 2.5.1.1 Control-Plane Handover Procedures The intra-NR handover includes the preparation and execution phases of the handover pro- cedure performed without 5GC involvement, that is, preparation messages are directly exchanged between the gNBs. The release of the resources at the source gNB during the handover completion phase is triggered by the target gNB. Fig. 2.28 shows the basic Source Target UPF(s) User data User data 0. Mobility control information provided by AMF 1. Measurement control and reports 2. Handover decision 3. Handover request 4. Admission control 5. Handover request acknowledge 6. RAN handover initiation 7. SN status transfer Detach from the source cell and synchronize with the target cell Deliver buffer data and new data from UPF(s) User data Buffer user data from the source 8. RAN handover completion Userldata Userldata 9. Path switch request 10. Path switch in UPF(s) End marker User data 11. Path switch request acknowledge 12. UE context release Figure 2.28 Intra-AMF/UPF handover in NR 8]. 262 Chapter 2 handover procedure where the AMF and the UPF entities do not change. The processing steps of this handover are as follows [8]: 1. The UE context within the source gNB contains information concerning roaming and access restrictions, which were provided either at connection 