One disclosure of the present specification provides a method by which user equipment (UE) performs a measurement. The method comprises the steps of: receiving, from a serving cell, a synchronization signal (SS)/physical broadcast channel (PBCH) block (SSB), wherein the SSB is used for radio link monitoring (RLM); and performing an RLM measurement on the basis of an RLM-reference signal (RLM-RS) included in the SSB, wherein, if the SSB is quasi-co-located (QCL) with respect to a channel-state information (CSI) reference signal (CSI-RS) resource, the RLM measurement is performed during a first evaluation period on the basis of a first value and, if the SSB is not QCL with respect to the CSI-RS resource, the RLM measurement is performed during a second evaluation period on the basis of a second value, and the first evaluation period is smaller than the second evaluation period.