A method for generating a downlink signal in a downlink MIMO (Multiple Input Multiple Output) comprises the steps of: mapping at least one transport block to at least one codeword; mapping at least one layer to each codeword; classifying at least one layer mapped to each codeword into a certain number of layer groups and performing layer permutation by the layer groups; and generating an OFDM (Orthogonal Frequency-Division Multiplexing) symbol using a signal which is permutated by the layer groups. A CRC (Cyclic Redundancy Check) is attached by the layer groups.