V2X communication method of terminal in wireless communication system, and terminal using method

A user equipment (UE) comprising:

• a transceiver configured to transmit and receive a radio signal;
• and
• a processor configured to be connected with the transceiver and to operate,
• wherein the processor is configured to:
• establish a radio resource control (RRC) connection with a base station,
• wherein, after establishing the RRC connection, the UE is in an RRC connected state;
• receive, from the base station, information for a resource pool of a sidelink;
• perform a measurement of a channel busy ratio (CBR) on the resource pool,
• wherein the CBR is defined as a portion of sub-channels in the resource pool whose sidelink received signal strength indicator (SL RSSI) measured by the UE exceed a threshold sensed over a CBR measurement window,
• wherein the CBR is applicable for at least one of a RRC idle intra frequency, a RRC idle inter frequency, a RRC connected intra frequency, or a RRC connected inter frequency, and
• wherein the SL RSSI is applicable for at least one of the RRC idle intra frequency, the RRC idle inter frequency, the RRC connected intra frequency, or the RRC connected inter frequency;
• receive at least one piece of downlink control information (DCI) of first DCI based on a first transmission time interval (TTI) and second DCI based on a second TTI from a base station through a physical downlink control channel (PDCCH);
• and
• perform an operation of the sidelink using one method of transmission based on the first TTI and transmission based on the second TTI on the basis of the at least one piece of DCI,
• wherein the first TTI is shorter than the second TTI, a first radio network temporary identifier (RNTI) set for the first DCI is different from a second RNTI set for the second DCI, and it is determined which of the transmission based on the first TTI and the transmission based on the second TTI is allowed on the basis of one of the first RNTI and the second RNTI,
• wherein an allowable range of the transmission based on the first TTI is set differently for each CBR, and
• wherein user equipment assistance information for the transmission based on the first TTI is independently reported from user equipment assistance information for the transmission based on the second TTI.