-Uu interface, the procedure for which includes putting mechanisms in place to encrypt the traffic and RRC signaling flows, and to control the integrity of the RRC signaling flows; - control of handover: this procedure executes the changing of cell between two eNB entities (intra-system handover) or between an eNB entity and a base station from a second- or third-generation mobile network (inter- system handover); - measurement reporting: the eNB entity can trigger measurements carried out by the mobile, either periodically or on demand, to prepare for handover; - transport of the NAS messages exchanged between the mobile and the MME entity. From the point of view of the eNB entity, the mobile may be in one of two operational states: idle mode (RRC_IDLE) or connected mode (RRC_CONNECTED). In idle mode, the mobile is not known to the eNB entity. It remains in this state until the RRC connection setup procedure is completed. The setup procedure is triggered by the mobile when it wishes to transmit traffic or signaling data, the mobile being used the SRBO bearer. In connected mode, the mobile can transmit and receive signaling and traffic data. The mobile is attributed an identifier which is unique to the cell, the cell radio network temporary identity (C-RNTI). In this state, the mobile uses either the SRB1 bearer for RRC messages with possible associated NAS messages, or the SRB2 bearer for RRC messages transporting solely NAS messages. Table 2.2 summarizes the type of SRB, the mode of radio link control (RLC) protocol and the channels used by the different RRC messages over the radio interface. VoLTE and ViLTE MasterInformationBlock Transport Physical RLC mode Logical channel channel channel Not available SystemInformationBlock RLC mode Transport Physical Logical channel channel channel Not available DL-SCH PDSCH Paging Transport Physical RLC mode Logical channel channel channel Not available PDSCH ConnectionSetup ConnectionReject ConnectionReestablishment ConnectionReestablishmentReject Transport Physical RLC mo