Method for handling of a RRC connection request message of a remote UE by a relay UE in wireless communication system and a device therefor

A relay User Equipment (UE) configured to operate in a wireless communication system, the relay UE comprising:

• a Radio Frequency (RF) module;
• and
• a processor operably coupled with the RF module and configured to:
• receive a first Radio Resource Control (RRC) connection request message for establishing RRC connection of a remote UE from the remote UE which is configured to connect to the relay UE via sidelink,
• wherein the first RRC connection request message includes a service request message, an identity of the remote UE, a cause value, a call type, and Non Access Stratum (NAS) information,
• wherein the cause value and the call type are provided by a first RRC layer of the remote UE, and the cause value and the call type are included in a header of the first RRC connection request message by a first adaptation layer of the remote UE,
• wherein based on the relay UE being in RRC idle state, a second adaptation layer of the relay UE is configured to forward the NAS information, the cause value and the call type to a NAS layer of the relay UE, only when an indication indicates that the NAS information is included in the first RRC connection request message, wherein the NAS information, the cause value and the call type are de-capsulated by a second RRC layer of the relay UE,
• wherein the indication is included in the first RRC connection request message by the first adaptation layer,
• wherein the NAS layer of the relay UE is configured to trigger service request for the remote UE by transmitting the NAS information, the cause value and the call type to the second adaptation layer;
• transmit a second RRC connection request message with the identity of the remote UE to an eNB,
• transmit a first RRC connection setup message for the remote UE to the remote UE, after receiving a second RRC connection setup message for the relay UE from the eNB, and
• transmit a RRC connection setup complete message with the NAS information to the eNB.