The present invention relates to a wireless communication system, and more specifically, disclosed are a method and an apparatus for transmitting or receiving a downlink signal by considering an antenna port relationship. A method for user equipment receiving a physical downlink shared channel (PDSCH) signal in the wireless communication system, according to one embodiment of the present invention, comprises the steps of: determining a start symbol index of the PDSCH from the downlink subframe; and receiving the PDSCH signal based on the start symbol index. When the DCI is comprised according to DCI format 1A, and the downlink subframe is a multicast broadcast single frequency network (MBSFN) subframe, the start symbol index can be determined depending on a PDSCH start symbol value which is included in a PDSCH resource element mapping and Quasi co-location indicator (PQI) that is established by an upper layer.