 state machine and state transitions between NR/5GC, LTE/EPC, and LTE/5GC [1]. handled by the device through cell reselection, while in the connected state, the mobility is managed by the network based on measurements. Fig. 2.24 illustrates an overview of UE RRC state machine and state transitions in NR. A UE has only one RRC state in NR at a given time. The UE is either in RRC_CONNECTED state or in RRC_INACTIVE state when an RRC connection has been established; otherwise, if no RRC connection is established, the UE is in RRC_IDLE state. The RRC states can fur- ther be characterized as follows (see the summary in Table 2.2): RRC_IDLE: In this state, a UE-specific DRX may be configured by upper layers. A UE-controlled mobility based on network configuration will be used. The UE monitors short messages transmitted with P-RNTI over downlink control channel. It also moni- tors the PCH for CN paging using 5G-S-TMSI and performs neighboring cell measure- ments and cell (re) selection. It further acquires SI and can send SI request (if configured). RRC_INACTIVE: In this state, a UE-specific DRX may be configured by upper layers or by RRC layer. A UE-controlled mobility based on network configuration is used. The UE stores the inactive AS context and an RNA is configured by the RRC sublayer. The UE monitors short messages transmitted with P-RNTI over downlink control chan- nel. It monitors the PCH for CN paging using 5G-S-TMSI and RAN paging using full I-RNTI and performs neighboring cell measurements and cell (re) )selection. The UE fur- ther periodically performs RNA updates (RNAUs) when moving outside the configured RNA. It also acquires SI and can send SI request (if configured). RRC_CONNECTED: In this state, the UE stores the AS context. The network transfers unicast data to/from the UE. At the lower layers, the UE may be configured with a UE-specific DRX. For carrier-aggregation-capable UEs, the network may use one or 246 Chapter 2 more SCells, aggregated with the SpCell to increase operation bandwidth. For the UEs