 UE registration update. In order to track its movement within the network, the device searches for and measures SSBs similar to the initial cell search procedure. Once the device detects an SSB with a received power that exceeds the received power of its current SSB by a certain threshold, it detects the SIB1 of the new cell in order to acquire information about the tracking and RAN areas. 2.5.4 Measurements The UE in RRC_CONNECTED state conducts measurements on multiple beams (at least one) of a cell and averages the measurement results mainly in the form of power values, in order to derive the cell quality. Therefore, the UE is configured to consider a sub- set of the detected beams. Filtering is applied at two different levels namely at the physical New Radio Access Layer 2/3 Aspects and System Operation 271 RRC configures RRC configures RRC configures parameters parameters parameters UE implementation specific gNB beam 1 Layer 1 filtering Evaluation of gNB beam 2 Layer 1 filtering Layer 3 filtering consolidation/ reporting selection Cell quality for cell quality criteria gNB beam K Layer 1 filtering Nbest-beams K beams K beams Beams L3 beam filtering L3 beam filtering Beam selection for reporting L3 beam filtering RRC configures RRC configures parameters parameters Figure 2.30 NR RRM measurement model [8]. layer to derive beam quality and then at RRC level to derive cell quality from multiple beams. The cell quality from beam measurements is derived in the same way for the serving cell(s) and for the non-serving cell(s). The measurement reports may contain the measure- ment results of the Nbest-beams best beams, if the UE is configured by the gNB. The K beams correspond to the measurements on SSB or CSI-RS resources configured for layer 3 mobil- ity by gNB and detected by UE at layer 1. The corresponding high-level measurement model is illustrated in Fig. 2.30 where the para- meters can be described as follows [8]: A: The measurements (beam-specific samples) internal to the physical layer. Layer 1 filtering: