An operation method of a first terminal may include: configuring a Uu access link with a base station, and receiving a first message from the base station, the first message including a relay RNTI for identifying the first terminal, a node address of the base station, and a RAP entity ID for identifying a RAP entity configured for the first terminal; configuring a relay link with a second terminal when communication with the base station is disconnected; requesting link switching by transmitting to the base station a second message via the second terminal, the second message including the relay RNTI, node address, and RAP entity ID; and receiving a response to the second message from the base station via the second terminal, and switching a link with the base station from the Uu access link to the relay link.