Method and device for transmitting data in wireless communication system

A method for transmitting data in a wireless communication system by a control plane (CP) of an access network, the method comprising:

• receiving a first multicast session start request message from a core network;
• determining whether to use a unicast bearer or a multicast bearer to transmit multicast data;
• and
• notifying the core network and a distribution unit (DU) of the access network of a result of the determination,
• wherein the first multicast session start request message includes an identification of a packet data unit (PDU) session corresponding to a multicast service.

An apparatus of a control plane (CP) for transmitting data in a wireless communication system, the apparatus comprising:

• a transceiver;
• and
• a processor configured to:
• receive, through the transceiver, a first multicast session start request message including an identification of a packet data unit (PDU) session corresponding to a multicast service and information on a multicast group from a core network,
• transmit, through the transceiver, a second multicast session start request message including the information on the multicast group to a distribution unit (DU) of the access network,
• receive, through the transceiver, a second multicast session start response message in response to the second multicast session start request message from the DU of the access network, and
• transmit, through the transceiver, a first multicast session start response message to the core network in response to the first multicast session start request message.

An apparatus of a control plane (CP) for transmitting data in a wireless communication system, the apparatus comprising:

• a transceiver;
• and
• a processor configured to:
• receive, through the transceiver, a first multicast session start request message from a core network,
• determine whether to use a unicast bearer or a multicast bearer to transmit multicast data, and
• notify the core network and a distribution unit (DU) of the access network of a result of the determination,
• wherein the first multicast session start request message includes an identification of a packet data unit (PDU) session corresponding to a multicast service.