One disclosure of the present specification provides a method for performing a proximity service (ProSe). The method may be performed by a user equipment (UE) and comprise: performing, by the UE configured with a primary cell (Pcell) and a secondary cell (Scell), a switching between the ProSe and a cellular service with at least one of the Pcell and the Scell; transceiving a ProSe discovery signal with at least one or more adjacent UEs after performing a switching from the cellular service to the ProSe service; and transceiving a signal with the at least one of the Pcell and the Scell after performing a switching from the ProSe service to the cellular service. Here, the UE is allowed an interruption of up to one subframe that is N subframes before and after an uplink (UL) subframe configured for transmitting the ProSe discovery signal.