A method of transmitting a signal by a first user equipment, UE, between UEs of a wireless communication system, the method comprising: performing resource sensing in a resource discovery duration including a plurality of resource units; selecting a specific resource unit for transmitting the signal based on a result of the resource sensing; and transmitting the signal via the specific resource unit, at a first transmission time point or a second transmission time point, wherein, when transmitting the signal at the first transmission time point, the specific resource unit is occupied by a second UE and has a smallest reception power among the plurality of resource units, wherein the second transmission time point is a delayed transmission time point after the first transmission time point, wherein whether the signal is transmitted at the first transmission time point or the second transmission time point is based on whether a time delay requirement for the signal is satisfied at the second transmission time point, wherein when the time delay requirement is satisfied, the signal is transmitted at the second transmission time point, wherein when the time delay requirement is not satisfied: the signal is transmitted at the first transmission time point based on a first reference signal sequence in the specific resource unit, the first reference signal sequence is determined based on a second reference signal sequence of the second UE, a cyclic shift value of the first reference signal sequence has a least correlation relation with a cyclic shift value of the second reference signal sequence. performing resource sensing in a resource discovery duration including a plurality of resource units; selecting a specific resource unit for transmitting the signal based on a result of the resource sensing; and transmitting the signal via the specific resource unit, at a first transmission time point or a second transmission time point, wherein, when transmitting the signal at the first transmission time point, the specific resource unit is occupied by a second UE and has a smallest reception power among the plurality of resource units, wherein the second transmission time point is a delayed transmission time point after the first transmission time point, wherein whether the signal is transmitted at the first transmission time point or the second transmission time point is based on whether a time delay requirement for the signal is satisfied at the second transmission time point, wherein when the time delay requirement is satisfied, the signal is transmitted at the second transmission time point, wherein when the time delay requirement is not satisfied: the signal is transmitted at the first transmission time point based on a first reference signal sequence in the specific resource unit, the first reference signal sequence is determined based on a second reference signal sequence of the second UE, a cyclic shift value of the first reference signal sequence has a least correlation relation with a cyclic shift value of the second reference signal sequence. the signal is transmitted at the first transmission time point based on a first reference signal sequence in the specific resource unit, the first reference signal sequence is determined based on a second reference signal sequence of the second UE, a cyclic shift value of the first reference signal sequence has a least correlation relation with a cyclic shift value of the second reference signal sequence.