V2X communication method of terminal in wireless communication system, and terminal using method
Provided are a V2X communication method of a terminal in a wireless communication system and a terminal using the method. The method is characterized by: receiving at least one DCI of a first DCI based on a first TTI and a second DCI based on a second TTI, from a base station through a PDCCH; and, based on the at least one DCI, performing V2X communication by using one of the methods of transmission based on the first TTI and transmission based on the second TTI, wherein the first TTI is shorter than the second TTI, a first RNTI configured for the first DCI is different from a second RNTI configured for the second DCI, and which one between the first TTI-based transmission and the second TTI-based transmission is accepted is determined based on one of the first RNTI and the second RNTI.
1. A method for a sidelink of a user equipment (UE) in a wireless communication system, the method comprising:
establishing a radio resource control (RRC) connection with a base station,
wherein, after establishing the RRC connection, the UE is in an RRC connected state;
receiving, from the base station, information for a resource pool of the sidelink;
performing 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;
receiving 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
performing 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.
2. The method of claim 1 , wherein each of the first DCI and the second DCI is DCI for dynamic scheduling or semi-persistent scheduling.
3. The method of claim 1 , wherein a size of the first DCI is the same as a size of the second DCI.
4. The method of claim 1 , wherein the first DCI comprises a flag for distinguishing the first DCI and the second DCI.
5. The method of claim 1 , wherein when the first DCI is received, determination of a time to perform an initial transmission or a sidelink index field are interpreted on the basis of the second TTI.
6. The method of claim 1 , wherein, when performing the operation of the sidelink, scheduling for the operation of the sidelink based on the first TTI is performed by each subchannel group, and the subchannel group is a set of a predefined number of subchannels comprised in a V2X resource pool.
7. The method of claim 6 , wherein the scheduling is performed when a field configuration of a physical sidelink control channel (PSCCH) based on the first TTI and a number of resource blocks comprised in the PSCCH based on the first TTI are set to be the same those of a PSCCH based on the second TTI.
8. The method of claim 1 , wherein, when both the transmission based on the first TTI and the transmission based on the second TTI are allowed in a V2X resource pool, a physical sidelink shared channel (PSSCH) based on the first TTI comprises a field indicating the transmission based on the first TTI.
9. The method of claim 8 , wherein, when performing the operation of the sidelink, a field indicating a time interval between initial transmission and retransmission of the PSCCH is interpreted on the basis of the second TTI.
10. The method of claim 1 , wherein, when only the transmission based on the first TTI is allowed in a V2X resource pool, when performing the operation of the sidelink, a field indicating a time interval between initial transmission and retransmission of a PSCCH is interpreted on the basis of the first TTI.
11. The method of claim 1 , wherein the first DCI comprises a field indicating a transmission period allowed in a V2X pool and a number of aggregated first TTIs capable of the transmission based on the first TTI.
12. The method of claim 11 , wherein when performing the operation of the sidelink, resource exclusion is performed on the basis of the field indicating the transmission period allowed in the V2X pool and the number of aggregated first TTIs capable of the transmission based on the first TTI.
13. The method of claim 1 , wherein, when a size of the PSCCH based on the first TTI is greater than a size of the PSSCH based on the first TTI, a PSCCH based on the first TTI comprises an indicator indicating an index of a first TTI used for transmitting the PSSCH among a plurality of first TTIs corresponding to a PSCCH transmission interval.
14. 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.