Device and terminal operation in next generation mobile communication system

Abstract

Disclosed are a communication technique which merges, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of after a 4G system, and a system therefor. The present disclosure can be applied to intelligent services (for example, smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail, security- and safety-related services, and the like) on the basis of 5G communication technology and IoT-related technology. The present disclosure relates to an operation method of a terminal in a wireless communication system and, particularly, to a method and a device for performing same, the method comprising the steps of: generating master cell group (MCG) failure information, transmitting the MCG failure information to a base station of a secondary cell group (SCG), receiving a radio resource control (RRC) reconfiguration message from the base station, and transmitting an RRC reconfiguration completion message on the basis of the RRC reconfiguration message, wherein, if the RRC reconfiguration message is included in a downlink information transfer message so as to be received via signaling radio bearer (SRB) 3 of the SCG, the RRC reconfiguration completion message is transmitted via configured SRB1 on the basis of the RRC reconfiguration message.