on setup [1,8]. In RRC_IDLE state there is no UE context, that is, the parameters necessary for communica- tion between the device and the network, in the radio access network, and the device is not registered to a specific cell. From the CN perspective, the device is in the CM-IDLE state where no data transfer may be performed since the device is in a sleep mode to conserve the battery. The idle mode UEs periodically wake up to receive paging messages, if any, from the network. In this mode, the mobility is managed by the device through cell reselection. The uplink synchronization is not maintained in the idle mode, and thus the UE is required to per- form a random-access procedure in order to transition to the connected mode. As part of tran- sitioning to the RRC_CONNECTED state, the UE context is established in the device and the 244 Chapter 2 network. From the CN perspective the device is in the CM-CONNECTED state and registered with the network. The cell to which the device belongs is known and a temporary identity for the device, that is, C-RNTI is used to identify the UE in NG-RAN while in the connected mode. The connected mode is intended for data transfer to/from the device; however, a DRX cycle can be configured during inactive times to reduce the UE power consumption. Since there is an already-established UE context in the gNB in the connected mode, transition from DRX mode and starting data transfer is relatively fast, requiring no connection setup. In this mode, the mobility is managed by the network. The device provides neighbor cell measure- ments to the network, and the network would instruct the device to perform a handover when necessary. The UE may lose uplink synchronization and may need to perform random-access procedure to be synchronized. The LTE system only supports idle and connected modes. In practice, the idle mode serves as the primary means to reduce the device power consumption during operation in the net- work. However, intermittent transmission of small packets by some delay-sensit