Method and device for performing sidelink communication

A method for performing sidelink (SL) communication by a third apparatus, the method including:

• receiving information on a plurality of resources from a second apparatus;
• determining whether a decoding of a transport block for a PSSCH by a fourth apparatus is successful based on a PSFCH related to the PSSCH transmitted from the second apparatus to the fourth apparatus on a first resource among the plurality of resources;
• determining whether to use resources after the first resource among the plurality of resources as a candidate resource for SL transmission by the third apparatus based on whether the decoding by the fourth apparatus is successful;
• and
• performing SL communication based on the determination related to whether to use the resources after the first resource as the candidate resource for the SL transmission by the third apparatus,
• wherein whether to use the resources after the first resource as the candidate resource is determined based on at least one of a congestion level, SL channel quality, service type or a QoS parameter related to a service.

A first apparatus for performing sidelink (SL) communication, the first apparatus including:

• at least one memory storing instructions;
• at least one transceiver;
• and
• at least one processor connecting the at least one memory and the at least one transceiver,
• wherein the at least one processor is configured to:
• control the at least one transceiver to receive information related to a plurality of resources from a second apparatus,
• control the at least one transceiver to receive a physical sidelink share channel (PSSCH) and a physical sidelink control channel (PSCCH) from the second apparatus on a first resource among the plurality of resources,
• determine resources after the first resource among the plurality of resources as a candidate resource for SL transmission by the first apparatus based on a successful decoding of a transport block received through the PSSCH, and
• perform SL communication based on the candidate resource for the SL transmission by the first apparatus,
• wherein the resources after the first resource determined as the candidate resource are resources after a a processing time required for the first apparatus to transmit hybrid automatic repeat request (HARQ) feedback information through a physical sidelink feedback channel (PSFCH) related to the PSSCH to the second apparatus has elapsed or processing of the HARQ feedback information is completed by the second apparatus after the second apparatus receives the HARQ feedback information.