A method by which a first wireless device tracks a channel in a wireless AV system, according to one embodiment of the present invention, comprises the steps of: receiving a radio signal including a first part related to a preamble and a second part related to a data block and a GI; estimating an initial channel on the basis of the preamble; estimating a residual channel on the basis of the GI, wherein a reconstruction sequence reconstructed on the basis of a Golay sequence having a predetermined length is applied to the GI; and updating a channel on the basis of first information acquired on the basis of the initial channel estimation and second information acquired on the basis of the residual channel estimation.