Wireless communication method using txop and wireless communication terminal using same

A wireless communication terminal that wirelessly communicates, the wireless communication terminal comprising:

• a transceiver for transmitting and receiving a wireless signal;
• and
• a processor for processing the wireless signal,
• wherein the processor is configured to:
• perform a transmission based on a transmission opportunity (TXOP) limit which is a maximum value of a TXOP, which is a time interval in which a wireless communication terminal has a right to initiate a frame exchange sequence in a wireless medium,
• transmit a Null Data Packet Announcement (NDPA) frame informing that a sounding protocol sequence is initiated,
• transmit a Null Data Packet (NDP) frame after a predetermined time from when the NDPA is transmitted,
• transmit a Beamforming Report Poll (BRP) trigger frame to other wireless communication terminals after the predetermined time from when the NDP frame is transmitted, wherein the BRP trigger frame triggers simultaneous transmission of feedback frames from the other wireless communication terminals using a plurality of user info fields, and
• when the wireless communication terminal transmits the NDPA frame, the NDP frame, and the BRP trigger frame within the TXOP limit, receive at least one of the feedback frames from the other wireless communication terminals, wherein the receiving at least one of the feedback frames is completed after the TXOP limit is exceeded, wherein the at least one of the feedback frames is transmitted after the predetermined time from when the BRP trigger frame is received, wherein the at least one of the feedback frames is transmitted by using trigger-based physical layer protocol data unit (PPDU),
• wherein each of the feedback frames indicates a state of a channel measured using the NDP frame by a transmitter of the each of the feedback frames, wherein the state of the channel is to be used for a Multi Input Multi Output (MIMO) transmission to the transmitter of the each of the feedback frames or is to be used for a beamforming transmission to the transmitter of the each of the feedback frames.

A method of operating a wireless communication terminal that wirelessly communicates, the method comprising:

• performing a transmission within a transmission opportunity (TXOP) limit which is a maximum value of a TXOP, which is a time interval in which a wireless communication terminal has a right to initiate a frame exchange sequence in a wireless medium,
• transmitting a Null Data Packet Announcement (NDPA) frame informing that a sounding protocol sequence is initiated,
• transmitting a Null Data Packet (NDP) frame after a predetermined time from when the NDPA is transmitted,
• transmitting, to other wireless communication terminals, a Beamforming Report Poll (BRP) trigger frame after the predetermined time from when the NDP frame is transmitted, wherein the BRP trigger frame triggers simultaneous transmission of feedback frames from the other wireless communication terminals using a plurality of user info fields, and
• when the wireless communication terminal transmits the NDPA frame, the NDP frame, and the BRP trigger frame within the TXOP limit, receiving the at least one of the feedback frames from the other wireless communication terminals, wherein the receiving at least one of the feedback frames is completed after the TXOP limit is exceeded, wherein the at least one of the feedback frames is transmitted after the predetermined time from when the BRP trigger frame is received, wherein the at least one of the feedback frames is transmitted by using trigger-based physical layer protocol data unit (PPDU),
• wherein each of the feedback frames indicates a state of a channel measured using the NDP frame by a transmitter of the each of the feedback frames, wherein the state of the channel is to be used for a Multi Input Multi Output (MIMO) transmission to the transmitter of the each of the feedback frames or is to be used for a beamforming transmission to the transmitter of the each of the feedback frames.