Method and device for performing sensing in wireless LAN system

A first station (STA) configured to operate in a wireless local area network (WLAN) system, the first STA comprising:

• a transceiver transmitting and receiving a radio signal;
• and
• a processor connected to the transceiver, wherein the processor is adapted to:
• transmit a first sensing frame,
• wherein the first sensing frame includes information related to a second STA operating as a sensing responder,
• wherein the first sensing frame further includes bit information indicating whether the first sensing frame is used as a null data physical protocol data unit announcement (NDPA) frame or a sensing initiation frame,
• wherein the NDPA frame is followed by a null data physical protocol data unit (NDP frame transmitted by the first STA;
• based on the bit information indicating the first sensing frame used as the sensing initiation frame, receive, from the second STA, a second sensing frame,
• wherein an interframe space (IFS) between the first sensing frame and the second sensing frame is defined as a short IFS (SIFS),
• wherein the second sensing frame is followed by a sensing measurement signal transmitted by the second STA,
• wherein an IFS between the second sensing frame and the sensing measurement signal is defined as an SIFS,
• wherein the second sensing frame includes strength information related to the sensing measurement signal, information related to a number of spatial streams for the sensing measurement signal, and information related to a number of transmissions for the sensing measurement signal;
• and
• receive, from the second STA, the sensing measurement signal.