A method of transmitting data in a wireless local area network is provided. The method includes the steps of: generating a data unit including a MAC (Medium Access Control) header and MSDU (MAC Service Data Unit), generating an encoded data unit by encoding the data unit, generating one or more spatial blocks by dividing the encoded data unit, dividing each of the one or more spatial block into a first block and a second block, generating a first interleaved block and a second interleaved block by interleaving the first block and the second block respectively, generating a first mapped sequence by mapping the first interleaved block into signal constellation, generating a second mapped sequence by mapping the second interleaved block into signal constellation, generating the transmission signal by performing IDFT (Inverse Discrete Fourier Transform) to the first mapped sequence and the second mapped sequence; and transmitting the transmission signal.