In a wireless local area network (LAN) system, a transmitting station (STA) may transmit a peer-to-peer (P2P) transmission request frame to an access point (AP). The transmitting STA may receive a P2P transmission response frame from the AP. The transmitting STA may receive a trigger frame from the AP. The trigger frame may include information related to whether same is for an uplink, P2P transmission or both an uplink and P2P transmission. The transmitting STA may transmit data to a receiving STA. The transmitting STA and the receiving STA may be non-AP STAs. The transmitting STA may transmit a null data packet announcement (NDPA) frame and a null data packet (NDP) frame to the receiving STA. The transmitting STA may receive, from the receiving STA, a feedback frame including state information for the channel between the transmitting STA and the receiving STA.