bile UE from the old serving node. In the case where the request fails, the NG-RAN node triggers a new RRC connection. 1.3.2.3. Mobility in the RRC_Connected state When the mobile is in the RRC_CONNECTED state and CM_CONNECTED state, its mobility is controlled by the NG-RAN node via the handover mechanism between a source radio node and a target radio node, or between two beams of the same radio node. In the case of a handover, the NG-RAN node exchanges RRC signaling with the mobile. There are several types of handover: - on the Xn interface between two neighboring connected nodes; - on the NG interface with the UPF. In the case of beam-based coverage, the beam selection is carried out at the MAC (Medium Access Control) layer of the mobile from mobile measurements. No RRC signaling occurs when the beam is changing since the mobile was configured at the beginning of the radio connection in terms of the measurements to be carried out (Measurement Objects). The mobile makes radio measurements on one or more beams of a cell and determines: - the radio quality of the beam by filtering the measurements on the L1 layer; - the quality of the radio link of the cell by averaging the measurement of the different beams at the level of the L3-RRC layer. The mobile also carries out measurements on the quality of the SSB block (Synchronization Signal and Broadcast) of the beams under the coverage of the cell, and also the quality of the neighboring intra- and inter-band cells. Each SSB measurement is seen by the mobile as a different cell. Table 1.1 summarizes the different cases. NG-RAN Network - Functional Architecture RRC_IDLE RRC_INACTIVE RRC_CONNECTED Cell selection is controlled by the UE in the function of radio UE mobility is known by the access network parameters (AS: Access Stratum). core network. The UE listens to broadcast signal. The core network knows the identity of the radio node Paging notifications are Paging notifications are with which the terminal is initiated by the core network. initiated by the NG-RAN co