econfiguration message including the reconfigwithSync. The main differences between LTE and NR regarding mobility come from the beam-based measurement configurations. NR allows the reference signal to be SSB for the IDLE state, and SSB and/or CSI-RS for the CONNECTED state. The UE measures multiple beams of a cell and derives the cell quality from multiple beams. Measurement reports may contain beam results (beam identifier and optionally its measurement result) in addition to cell quantities. 3.4.5.2.4 Radio Link Failure Recovery Reestablishment procedures similar to LTE are reused in NR for recovery after radio link failure (RLF). Unlike LTE, the RRC Reestablishment message itself does not contain any configuration information other than security parameters. This reestablishes security between the UE and the network. A subsequent RRC Reconfiguration message is then sent with security to provide all the configuration information. Another difference compared with LTE is that if the target cannot continue with the reestablishment, for example if it does not have the UE context, then it can use a fallback procedure and convert the reestablishment to a new RRC connection set up procedure without the UE having to initiate a RACH attempt again. Figure 3.4.11 shows the successful RRC connection reestablishment and Figure 3.4.12 illustrates the fallback message flow. Figure 3.4.11 Successful RRC connection Network reestablishment. (Source: Reproduced by permission of © 3GPP). RRCReestablishmentRequest RRCReestablishment RRCReestablishmentComplete 3 5G System Overview Network Figure 3.4.12 RRC connection reestablishment with fallback. (Source: Reproduced by permission of © 3GPP). RRCReestablishmentRequest RRCSetup RRCSetupComplete 3.4.5.2.5 UE AS Capability Retrieval The UE capability enquiry procedure is used to retrieve and store the UE AS capability in the core network as part of the UE connection establishment procedure. This procedure is normally only run once per UE registration. For subsequent connection establish