Method and device for requesting feedback of portion of band for sta operating only in 20/80/160 mhz in wireless lan system

A receiving station (STA) in a wireless local area network (WLAN) system, the receiving STA comprising:

• a memory;
• a transceiver;
• and
• a processor being operatively connected to the memory and the transceiver,
• wherein the processor is configured to:
• receive a Null Data Packet Announcement (NDPA) frame from a transmitting STA;
• receive an NDP frame from the transmitting STA;
• and
• transmit a feedback frame to the transmitting STA based on the NDPA frame and the NDP frame through a preset bandwidth,
• wherein the NDPA frame includes information on a partial band,
• wherein the information on the partial band includes a bitmap composed of first to ninth bits,
• wherein the first bit includes information on a channel unit requesting feedback information,
• wherein when the first bit is set to 0, the second to ninth bits are bits that requests feedback information for the lowest frequency 20 MHz channel to the highest frequency 20 MHz channel in the preset bandwidth,
• wherein when the receiving STA is an STA that operates only at 20 MHz and the first bit is set to 1, the second bit is a bit that requests feedback information for 242 Resource Unit (RU) in the lowest frequency 40 MHz channel in the preset bandwidth, the third bit is a bit that requests feedback information for 242RU in the second lowest frequency 40 MHz channel in the preset bandwidth, the fourth bit is a bit that requests feedback information for 242RU in the third lowest frequency 40 MHz channel in the preset bandwidth, the fifth bit is a bit that requests feedback information for 242RU in the fourth lowest frequency 40 MHz channel in the preset bandwidth, the sixth bit is a bit that requests feedback information for 242RU in the fifth lowest frequency 40 MHz channel in the preset bandwidth, the seventh bit is a bit that requests feedback information for 242RU in the sixth lowest frequency 40 MHz channel in the preset bandwidth, the eighth bit is a bit that requests feedback information for 242RU in the seventh lowest frequency 40 MHz channel in the preset bandwidth, and the ninth bit is a bit that requests feedback information for 242RU in the highest frequency 40 MHz channel in the preset bandwidth, and
• wherein the 242RU is a resource unit composed of 242 tones.

A method in a wireless local area network (WLAN) system, the method comprising:

• transmitting, by a transmitting station (STA), a null data packet announcement (NDPA) frame to a receiving STA;
• transmitting, by the transmitting STA, an NDP frame to the receiving STA;
• and
• receiving, by the transmitting STA, a feedback frame based on the NDPA frame and the NDP frame from the receiving STA through a preset bandwidth,
• wherein the NDPA frame includes information on a partial band,
• wherein the information on the partial band includes a bitmap composed of first to ninth bits,
• wherein the first bit includes information on a channel unit requesting feedback information,
• wherein when the first bit is set to 0, the second to ninth bits are bits that requests feedback information for the lowest frequency 20 MHz channel to the highest frequency 20 MHz channel in the preset bandwidth,
• wherein when the receiving STA is an STA that operates only at 20 MHz and the first bit is set to 1, the second bit is a bit that requests feedback information for 242 Resource Unit (RU) in the lowest frequency 40 MHz channel in the preset bandwidth, the third bit is a bit that requests feedback information for 242RU in the second lowest frequency 40 MHz channel in the preset bandwidth, the fourth bit is a bit that requests feedback information for 242RU in the third lowest frequency 40 MHz channel in the preset bandwidth, the fifth bit is a bit that requests feedback information for 242RU in the fourth lowest frequency 40 MHz channel in the preset bandwidth, the sixth bit is a bit that requests feedback information for 242RU in the fifth lowest frequency 40 MHz channel in the preset bandwidth, the seventh bit is a bit that requests feedback information for 242RU in the sixth lowest frequency 40 MHz channel in the preset bandwidth, the eighth bit is a bit that requests feedback information for 242RU in the seventh lowest frequency 40 MHz channel in the preset bandwidth, and the ninth bit is a bit that requests feedback information for 242RU in the highest frequency 40 MHz channel in the preset bandwidth, and
• wherein the 242RU is a resource unit composed of 242 tones.