Channel in a wireless communication system, the sounding method and apparatus therefor

In the sounding method of STA (Station) for transmitting the feedback information relating to: (Downink DL) channel state, NDP (Null data packet) downlink from, WLAN (Wireless LAN) system according to an embodiment of the present invention receiving a NDPA (NDP announcement) frame indicating the transmission of the frame; Receiving the NDP frame; Receiving a trigger frame including the resource allocation information assigned to the STA; Generating channel state information based on the training field included in the NDP frame; Sending: Multiple user (Multi-User MU): and a UL (Uplink UL) by using the frequency resources for the feedback frame including the channel state information indicates that the resource allocation information It may contain.