, as defined in [4]. For non-default association, the network may configure each PO to start on any allowed slot (e.g. not UL slot, should be part of the paging search space). Alternatively, POs are situated on consecutive PDCCH monitoring occasions. 7.7.4 Overview of Idle and Inactive Mode Mobility Public Land Mobile Network (PLMN) selection is a part of the NAS procedures, and AS helps NAS to perform the procedure by searching available PLMNs if requested to do SO by NAS - the PLMN is available if the measured RSRP value of the cell is greater than -110 dBm. A priority value can be assigned to PLMNs by the home PLMN operator. The UE shall search for higher-priority PLMNs at regular time intervals and search for a suitable cell if another PLMN has been selected. For example, the operator may have configured pre- ferred roaming operators for the USIM (Universal Subscriber Identity Module) card. When the UE is roaming and not camped to the preferred operators, it tries to periodi- cally find the preferred operator. If the UE is unable to find a suitable cell to camp on or if the location registration failed, it attempts to camp on a cell irrespective of the PLMN identity and enters a "limited service" state in which only emergency calls can be made. A USIM must be inserted in the UE in order to perform the registration. As in LTE, NR uses only USIM as it can provide stronger protection against identity theft compared to SIM (Figure 7.19). Once NAS has selected a PLMN, AS tries to select a cell of the selected PLMN based on the radio measurements and starts receiving the BCHs of that cell and find out if the cell is suitable for camping, which requires that the cell not be barred and adequate radio quality . After this procedure, called cell selection, the UE must register itself to the network, thus promoting the selected PLMN to the registered PLMN with corre- sponding NAS procedures. If the UE is able to find a cell that is deemed as a better 7 5G Radio Protocols Location registration response Location PLMN sele