Ofdm transmission method and device in wireless lan system

An OFDM transmission method and device in a wireless LAN system are disclosed. An OFDM transmission device ini a wireless LAN system according to one embodiment of the present invention comprises: a signal repetition unit for repeating an encoded signal in block units and outputting both the encoded signal and a repeated signal; an interleaver for outputting an interleaved signal by interleaving the encoded signal and the repeated signal; a modulation unit for outputting modulated symbols by modulating the interleaved signal; and a phase rotation unit for shifting the phases of the modulated symbols.