Sidelink discovery-related operation method in wireless communication system

1. An operation method of a user equipment (UE) related to sidelink discovery in a wireless communication system, the method comprising:

obtaining, by the UE, a sidelink discovery message; and

transmitting, by the UE, the sidelink discovery message;

wherein the sidelink discovery message is delivered to a MAC (Medium Access Control) layer using a logical channel (LCH) for sidelink discovery,

wherein the LCH for sidelink discovery has a fixed LCID (Logical Channel Identity) and a fixed priority, and

wherein the sidelink discovery message is transmitted based on the fixed LCID and the fixed priority.

2. The method of claim 1 , wherein the fixed priority has a constant value regardless of whether the UE is a relay UE or a remote UE, a change in a service type, a change in a congestion level, and a change in a zone.

3. The method of claim 1 , wherein the sidelink discovery message is not multiplexed with data for a different service or a different channel, except for data related to a radio resource control (RRC) connection.

4. The method of claim 1 , wherein a pre-emption priority threshold of the sidelink discovery message has a unique value.

5. The method of claim 1 , wherein the UE is configured to request a remote UE to exclude a resource region related to reception of the sidelink discovery message from candidate transmission resources.

6. The method of claim 5 , wherein the sidelink discovery message is a response to a solicitation discovery message received from a remote UE.

7. The method of claim 1 , wherein sidelink control information (SCI) transmitted by the UE includes a sidelink discovery message indicator indicating that a MAC protocol data unit (PDU) is related to the sidelink discovery message.

8. The method of claim 7 , wherein the sidelink discovery message indicator includes information indicating that the message is to discover a relay UE.

9. The method of claim 8 , wherein the information is 2-bit information indicating that the sidelink discovery message indicator is any one of a Model A discovery message, a Model B solicitation message, and a Model B discovery message.

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

at least one processor; and

at least one computer memory operatively connected to the at least one processor and configured to store instructions for causing the at least one processor to perform operations when being executed,

wherein the operations include:

obtaining, by the UE, a sidelink discovery message; and

transmitting, by the UE, the sidelink discovery message;

wherein the sidelink discovery message is delivered to a MAC (Medium Access Control) layer using a logical channel (LCH),

wherein the LCH for sidelink discovery has a fixed LCID (Logical Channel Identity) and a fixed priority, and

wherein the sidelink discovery message is transmitted based on the fixed LCID and the fixed priority.

11. The UE of claim 10 , wherein the UE is configured to communicate with at least one of another UE, a UE related to an autonomous vehicle, a base station, or a network.

12. A processing device configured to control a user equipment (UE) to operate in a wireless communication system, the processing device comprising:

at least one processor; and

at least one memory operatively connected to the at least one processor and storing at least one instructions that, when executed by the at least one processor, causes the at least one processor to perform operations comprising:

obtaining, by the UE, a sidelink discovery message; and

transmitting, by the UE, the sidelink discovery message;

wherein the sidelink discovery message is delivered to a MAC (Medium Access Control) layer using a logical channel (LCH),

wherein the LCH for sidelink discovery has a fixed LCID (Logical Channel Identity) and a fixed priority, and

wherein the sidelink discovery message is transmitted based on the fixed LCID and the fixed priority.

13. A non-volatile computer-readable storage medium for storing at least one computer program including an instruction for causing at least one processor to perform operations for a user equipment (UE) when being executed by the at least one processor, the operations comprising:

obtaining, by the UE, a sidelink discovery message; and

transmitting, by the UE, the sidelink discovery message;

wherein the sidelink discovery message is delivered to a MAC (Medium Access Control) layer using a logical channel (LCH),

wherein the LCH for sidelink discovery has a fixed LCID (Logical Channel Identity) and a fixed priority, and

wherein the sidelink discovery message is transmitted based on the fixed LCID and the fixed priority.