Method and device for performing sounding procedure in wireless LAN system

A first station (STA) comprising:

• at least one transceiver;
• and
• at least one processor coupled with the at least one transceiver,
• wherein the at least one processor is configured to:
• receive a null data PPDU (NDP) announcement frame from a second STA in a first frequency unit for a first type physical layer protocol data unit (PPDU) format related to a first type STA and a second frequency unit for a second type PPDU format related to a second type STA;
• and
• transmit a feedback frame related to one or more of the first frequency unit or the second frequency unit to the second STA,
• wherein the NDP announcement frame is defined as a single type NDP announcement frame format for the first frequency unit and the second frequency unit and includes a STA Info field set to a specific association identifier (AID) value, and
• wherein the STA Info field is located within the NDP announcement frame based on at least one of a location of a first type STA Info field for the first type STA or a location of a second type STA Info field for the second type STA.

A second station (STA) comprising:

• at least one transceiver;
• and
• at least one processor coupled with the at least one transceiver,
• wherein the at least one processor is configured to:
• transmit a null data PPDU (NDP) announcement frame to a first STA in a first frequency unit for a first type physical layer protocol data unit (PPDU) format related to a first type STA and a second frequency unit for a second type PPDU format related to a second type STA;
• and
• receive a feedback frame related to one or more of the first frequency unit or the second frequency unit from the first STA,
• wherein the NDP announcement frame is defined as a single type NDP announcement frame format for the first frequency unit and the second frequency unit and includes a STA Info field set to a specific association identifier (AID) value, and
• wherein the STA Info field is located within the NDP announcement frame based on at least one of a location of a first type STA Info field for the first type STA or a location of a second type STA Info field for the second type STA.