The present specification discloses a method by which a station (STA) operating in a wireless LAN system transmits a signal. Here, the method comprises the steps of: receiving a first frame including resource allocation information from an AP station; and transmitting a second frame to the AP station on the basis of the resource allocation information, wherein the first frame includes an allocation type part and a trigger frame body part, and the second frame can be set to an NDP frame and the trigger frame body part can include allocation information on the NDP frame when the allocation type part is set to a first value.