Apparatus and method of uplink beamforming in wireless local area network system

An operating method of a first device communicating with a second device in a wireless local area network (WLAN), the operating method comprising:

• receiving, from the second device, a null data packet announcement (NDPA) signal and a null data packet (NDP);
• preparing an uplink beamforming matrix based on the NDP;
• receiving a trigger frame including an uplink beamforming-related sub-field from the second device;
• beamforming an uplink signal according to the uplink beamforming matrix based on a value of the uplink beamforming-related sub-field;
• and
• transmitting the beamformed uplink signal to the second device,
• wherein the uplink beamforming-related sub-field is defined to indicate whether the second device requests uplink beamforming from the first device.

An operating method of a first device communicating with a second device in a wireless local area network (WLAN), the operating method comprising:

• receiving, from the second device, an aggregated-media access control (MAC) protocol data unit (A-MPDU) comprising a first trigger frame corresponding to a first band;
• preparing an uplink beamforming matrix based on a value of an uplink beamforming-related first sub-field included in a preamble corresponding to the first band of the A-MPDU;
• beamforming, according to the uplink beamforming matrix, an A-MPDU;
• and
• transmitting the beamformed A-MPDU to the second device based on a value of an uplink beamforming-related second sub-field included in the first trigger frame,
• wherein the uplink beamforming-related first sub-field is defined to indicate whether the first device has to prepare the uplink beamforming matrix, and
• wherein the uplink beamforming-related second sub-field is defined to indicate whether the second device requests the uplink beamforming from the first device.