USER DEVICE, GATEWAY DEVICE, WIRELESS BASE STATION, MOBILE COMMUNICATION SYSTEM, AND MOBILE COMMUNICATION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a user device, a gateway device, a wireless base station, a mobile communication system, and a mobile communication method by which it is possible to greatly reduce the number of control signals for small data transmission (SDT).SOLUTION: A UE 100 transitions from an RRC-IDLE state in which a communication bearer of a control plane has not been established and an EMM-IDLE state in which user plane communication is not yet possible to an RRC-CONNECTED state in which the communication bearer of the control plane has been established and the EMM-IDLE state. While the RRC-CONNECTED state and the EMM-IDLE state are in effect, the UE 100 sends user data input thereto through the communication bearer of the control plane. Upon the completion of the sending of the user data, the UE 100 transitions from the RRC-CONNECTED state and EMM-IDLE state to the RRC-IDLE state and EMM-IDLE state.