Method and device for base station to report lbt failure information in next-generation mobile communication system operating in unlicensed frequency band

A terminal in a wireless communication system, the terminal comprising:

• a transceiver;
• and
• a controller connected to the transceiver, wherein the controller is configured to:
• perform listen-before-talk (LBT) for uplink transmission;
• detect an LBT failure while performing the LBT;
• and
• determine a radio link failure (RLF) in case that the number of detected LBT failures is equal to or more than a preconfigured number.

A method performed by a base station in a wireless communication system, the method comprising:

• receiving, from a terminal, a first radio resource control (RRC) message including an indicator indicating radio link failure (RLF)-related information;
• transmitting, to the terminal, a message for requesting an RLF report;
• and
• receiving, from the terminal, the RLF report comprising information indicating that a cause of the RLF is a listen-before-talk (LBT) failure,
• wherein the RLF due to the LBT failure is determined in case that the number of detected LBT failures is equal to or more than a preconfigured number.

A base station in a wireless communication system, the base station comprising:

• a transceiver;
• and
• a controller connected to the transceiver, wherein the controller is configured to:
• receive, from a terminal, a first radio resource control (RRC) message including an indicator indicating radio link failure (RLF)-related information;
• transmit, to the terminal, a message for requesting an RLF report;
• and
• receive, from the terminal, the RLF report comprising information indicating that a cause of the RLF is a listen-before-talk (LBT) failure,
• wherein the RLF due to the LBT failure is determined in case that the number of detected LBT failures is equal to or more than a preconfigured number.