Method and apparatus for performing sidelink communication by UE in NR V2X

1. A method for performing sidelink communication by a first apparatus, the method comprising:

transmitting, to a second apparatus, a direct communication request message to establish unicast link, which includes an identifier of the first apparatus and information regarding at least one service type,

wherein the direct communication request message further includes information regarding a security capability of the first apparatus, and

wherein based on that an identifier of the second apparatus is provided, the direct communication request message further includes information regarding the identifier of the second apparatus;

transmitting, to the second apparatus, quality of service (QoS) information related to the at least one service type;

receiving, from the second apparatus, a direct communication accept message including an identifier of the second apparatus and the QoS information related to the at least one service type; and

performing the sidelink communication based on the unicast link between the first apparatus and the second apparatus.

2. The method of claim 1 , wherein the unicast link between the first apparatus and the second apparatus is established for the at least one service type based on the direct communication request message and the direct communication accept message.

3. The method of claim 1 , wherein the identifier of the first apparatus is an upper layer identifier of the first apparatus, and the identifier of the second apparatus is an upper layer identifier of the second apparatus.

4. The method of claim 1 , wherein the direct communication request message includes security information for an establishment of security between the first apparatus and the second apparatus.

5. The method of claim 1 , wherein the QoS information includes at least one QoS indicator value representing guaranteed bit rate (GBR) or non-GBR.

6. The method of claim 1 , wherein the QoS information includes at least one QoS indicator value representing priority and packet delay budget.

7. The method of claim 1 , wherein the direct communication request message includes restriction information related to the sidelink communication between the first apparatus and the second apparatus.

8. The method of claim 7 , wherein the restriction information includes information on transmission resources or reception resources of the first apparatus.

9. The method of claim 8 , wherein, based on the information on transmission resources or reception resources included in the restriction information, transmission resources for the sidelink communication is selected by the second apparatus.

10. The method of claim 9 , wherein the transmission resources selected by the second apparatus is different from the transmission resources or the reception resources of the first apparatus.

11. The method of claim 1 , wherein the direct communication request message includes hybrid automatic repeat request (HARQ) capability of the first apparatus.

12. The method of claim 11 , wherein the HARQ capability of the first apparatus includes at least one of whether the first apparatus supports sidelink HARQ feedback, whether the first apparatus supports HARQ combining, or maximum number of the sidelink HARQ process supported by the first apparatus.

13. The method of claim 12 , wherein, based on the HARQ capability included in the direct communication request message, transmission resources or retransmission resources for the sidelink communication is determined by the second apparatus.

14. A first apparatus performing sidelink communication, the first apparatus comprising:

one or more memories storing instructions;

one or more transceivers; and

one or more processors operably connected to the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions to:

transmit, to a second apparatus, a direct communication request message to establish unicast link, which includes an identifier of the first apparatus and information regarding at least one service type,

wherein the direct communication request message further includes information regarding a security capability of the first apparatus, and

wherein based on that an identifier of the second apparatus is provided, the direct communication request message further includes information regarding the identifier of the second apparatus;

transmit, to the second apparatus, quality of service (QoS) information related to the at least one service type;

receive, from the second apparatus, a direct communication accept message including an identifier of the second apparatus and the QoS information related to the at least one service type; and

perform the sidelink communication based on the unicast link between the first apparatus and the second apparatus.

15. An apparatus configured to control a first user equipment (UE) to perform sidelink communication, the apparatus comprising:

one or more processors; and

one or more memories operably connected to the one or more processors and storing instructions, wherein the one or more processors execute the instructions to:

transmit, to a second apparatus, a direct communication request message to establish unicast link, which includes an identifier of the first apparatus and information related to at least one service type,

wherein the direct communication request message further includes information regarding a security capability of the first apparatus, and

wherein based on that an identifier of the second apparatus is provided, the direct communication request message further includes information regarding the identifier of the second apparatus;

transmit, to the second apparatus, quality of service (QoS) information related to the at least one service type;

receive, from the second apparatus, a direct communication accept message including an identifier of the second apparatus and the QoS information related to the at least one service type; and

perform the sidelink communication based on the unicast link between the first apparatus and the second apparatus.