One disclosure of the present specification provides a method in which a terminal receives a sidelink synchronization signal (SLSS) from a neighboring terminal. The method includes: determining by the terminal a period and the number of times of transmitting the SLSSs; and transmitting by the terminal the SLSS during a first time duration defined on the basis of the period and the number of times. The transmitting of the SLSS may include detecting by the terminal an SLSS transmitted by the neighboring terminal in a second time duration within the first time duration. The terminal may discard transmission of an SLSS corresponding to the second time duration within the first time duration. The second time duration may be included in the first time duration, and the second time duration is less than or equal to 40% of the first time duration.