METHOD AND DEVICE FOR TRANSMITTING DATA IN CASE OF PDCP VERSION CHANGE IN WIRELESS COMMUNICATION SYSTEM

The present disclosure relates to a communication technique for converging a 5G communication system for supporting a higher data transfer rate beyond a 4G system with an IoT technology, and a system therefor. The present disclosure may be applied to intelligent services (for example, smart home, smart buildings, smart cities, smart cars or connected cars, health care, digital educations, retail business, security and safety-related services, etc.) on the basis of a 5G communication technology and an IoT-related technology. A method for transmitting data by a first communication device in the case of a packet data convergence protocol (PDCP) version change in a wireless communication system according to an embodiment of the present invention comprises the steps of: checking whether the PDCP version of a first PDCP entity for the first communication device is changed from the PDCP version of a second PDCP entity for a second communication device; when the PDCP version of the first PDCP entity is changed, identifying first data transmitted by the second PDCP entity to a radio link control (RLC) entity for the second communication device; and transmitting second data to a third communication device on the basis of the first data and a data transmission mode configured for the first communication device.