Method for transmitting data, and device therefor

An electronic device comprising:

• at least one wireless communication circuit configured to provide a first radio access technology (RAT) and a second RAT;
• a processor operatively connected to the at least one wireless communication circuit;
• and
• a memory operatively connected to the processor, wherein the memory stores instructions, and the processor is configured to:
• detect a packet data convergence protocol (PDCP) change from a first PDCP to a second PDCP at least by detecting a change in a PDCP version and/or in a PDCP key,
• identify, in response to detected PDCP change, at least one first data packet that is delivered from a PDCP layer to a lower layer and has not been transmitted by the electronic device, and
• when a transmission protocol of the at least one first data packet is a user datagram protocol, UDP, determine to reprocess the at least one first data packet by:
• storing the at least one first data packet in a buffer,
• changing at least a portion of the first data packet to at least one second data packet related to the second PDCP, and
• transmitting the at least one second data packet.