1. A method for receiving a downlink signal, the method performed by a user equipment (UE) and comprising:receiving downlink control information (DCI) including modulation and coding scheme (MCS) information and including resource allocation information indicating one or more physical resource blocks (PRBs) allocated to the UE;
receiving downlink data through a physical downlink shared channel (PDSCH) mapped to the one or more PRBs allocated to the UE based on the DCI; and
determining a transport block size of the downlink data among a plurality of predefined transport block sizes, based on the MCS information and a number, NPRB?, of the PRBs allocated to the UE,
wherein, if the density of downlink reference signals is greater than a reference value, the transport block size is determined based on a number, NPRB, of reduced PRBs rather than on NPRB?,
wherein NPRB is determined based on a value obtained by multiplying a positive real number less than 1, ? by the NPRB?, and
wherein ? is determined based on a ratio, NRE?/NRE, of a number, NRE?, of resource elements excluding resource elements used to receive the downlink reference signals from NRE to a number, NRE, of resource elements excluding resource elements included in orthogonal frequency division multiplexing (OFDM) symbols used to transmit a physical downlink control channel (PDCCH) from resource elements in a resource block.