Provided are methods and devices for transmitting/receiving downlink signals in a Wireless communication system. Carrier information is provided to user equipment, the carrier information including cell identifier information which indicates Whether a first cell identifier related to a first carrier operating on one resource block (RB) and a second cell identifier used for a cell-specific reference signal (CRS) on the first carrier are the same or different. If the second cell identifier is the same as the first cell identifier, the user equipment assumes that the number of antenna ports for the CRS on the first carrier is the same as the number of antenna ports for a reference signal defined for NB-IoT (reference signal for NB-IoT, NRS). If the second cell identifier is different from the first cell identifier, the carrier information further includes antenna port number information, and the user equipment assumes that the number of the antenna ports for the CRS is the same as the number of antenna ports based on the antenna port number information.