A method performed by a user equipment, UE, configured to operate in a wireless communication system, the method comprising: determining a candidate resource set that is initialized to a set of all candidate resources; determining a set of resources for a physical sidelink shared channel, PSSCH, transmission based on excluding a candidate resource from the candidate resource set; and performing the PSSCH transmission based on the set of resources, characterized in that: wherein the candidate resource is defined as a set of contiguous sub-channels in a subframe with index Y, a starting sub-channel in the set of contiguous sub-channels being a sub-channel with index X, wherein the candidate resource is excluded from the candidate resource set based on a subframe with index Y+J*RR_INVTX overlapping with a subframe with index M+ P_STEP *I_CANVAL for at least one integer J from 0 to Cresel-1, wherein * represents multiplication, wherein the RR_INVTX is related to a resource reservation interval of the UE, wherein the M is an index of a subframe which the UE has not monitored for transmissions of the UE, wherein the P_STEP is a positive integer, wherein the I_CANVAL related to a value allowed for resource reservation period, and wherein the Cresel is a number of subframes in a set of time and frequency resources for transmission opportunities of PSSCH. determining a candidate resource set that is initialized to a set of all candidate resources; determining a set of resources for a physical sidelink shared channel, PSSCH, transmission based on excluding a candidate resource from the candidate resource set; and performing the PSSCH transmission based on the set of resources, characterized in that: wherein the candidate resource is defined as a set of contiguous sub-channels in a subframe with index Y, a starting sub-channel in the set of contiguous sub-channels being a sub-channel with index X, wherein the candidate resource is excluded from the candidate resource set based on a subframe with index Y+J*RR_INVTX overlapping with a subframe with index M+ P_STEP *I_CANVAL for at least one integer J from 0 to Cresel-1, wherein * represents multiplication, wherein the RR_INVTX is related to a resource reservation interval of the UE, wherein the M is an index of a subframe which the UE has not monitored for transmissions of the UE, wherein the P_STEP is a positive integer, wherein the I_CANVAL related to a value allowed for resource reservation period, and wherein the Cresel is a number of subframes in a set of time and frequency resources for transmission opportunities of PSSCH. wherein the candidate resource is defined as a set of contiguous sub-channels in a subframe with index Y, a starting sub-channel in the set of contiguous sub-channels being a sub-channel with index X, wherein the candidate resource is excluded from the candidate resource set based on a subframe with index Y+J*RR_INVTX overlapping with a subframe with index M+ P_STEP *I_CANVAL for at least one integer J from 0 to Cresel-1, wherein * represents multiplication, wherein the RR_INVTX is related to a resource reservation interval of the UE, wherein the M is an index of a subframe which the UE has not monitored for transmissions of the UE, wherein the P_STEP is a positive integer, wherein the I_CANVAL related to a value allowed for resource reservation period, and wherein the Cresel is a number of subframes in a set of time and frequency resources for transmission opportunities of PSSCH.