Abstract: A method of link adaptation performed by an access point supporting multi user(MU) multiple input multiple output(MIMO) in wireless local area network system is provided. The method includes transmitting, to a first station, a physical layer convergence procedure (PLCP) protocol data unit (PPDU) containing a modulation and coding scheme(MCS) request(MRQ) and receiving, from the first station, a MCS feedback(MFB) in response to the MRQ, wherein the first station is one of destination stations of MU-MIMO transmission performed by the access point, and the MFB includes a recommended MCS value computed, by the first station, on the assumption that the first station, as a member of the destination stations, receives data transmitted over at least one spatial stream allocated to the first station in MU-MIMO transmission.

Abstract: A method for a channel sounding in a wireless local area network. A station receives a 20 MHz null data packet announcement (NDPA) frame and at least one duplicate 20 MHz NDPA frame. The at least one duplicate 20 MHz NDPA frame is a duplicate of the 20 MHz NDPA frame. The station also receives a null data packet (NDP) following the 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame. The bandwidth over which the 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame are transmitted is the same as a bandwidth over which the NDP is transmitted. The station transmits a report frame for the channel sounding. The 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame comprise bandwidth information indicating the bandwidth over which the frames are transmitted.

Abstract: In an aspect, a method of receiving a data unit, performed by an Access Point (AP), in a Wireless LAN (WLAN) system is provided. The method includes transmitting a signal protection frame, the signal protection frame comprising a group ID field indicating a Multiple Input Multiple Output (MIMO) transmission STA group including a first station (STA) and a second STA; and, a spatial stream field indicating a number of spatial streams allocated to each of member STAs included in the MIMO transmission STA group; receiving a first preamble for a first data unit from the first STA; receiving a second preamble for a second data unit from the second STA; and simultaneously receiving the first data unit from the first STA and the second data unit from the second STA.

Abstract: A method and a device for reporting a modulation and coding scheme (MCS) feedback in a wireless local area network are provided. A responding station receives, from a requesting station, a requesting Physical layer Protocol Data Unit (PPDU) for requesting a MCS feedback via a plurality of spatial streams. A recommended MCS is estimated under an assumption that the requesting station will transmit at least one first spatial stream among the plurality of spatial streams used for the requesting PPDU, The responding station transmits, to the requesting station, the MCS feedback including a recommended MCS field indicating the recommended MCS and a recommended stream field indicating a number of at least one recommended spatial stream. A number of the at least one first spatial stream used for estimating the recommended MCS is equal to the number of the at least one recommended spatial stream.

Abstract: Disclosed are a method and an apparatus for feed back of channel state information. The method for transmitting channel state information comprises the steps of: receiving a null data packet (NDP) frame; calculating signal to noise ratio (SNR) information based on subcarrier information of at least one spatial stream via which the NDP frame is transmitted; and calculating a compressed beamforming feedback matrix including channel state information based on the information on the subcarrier used in transmitting the spatial stream. Thus, accurate feedback information is calculated from a frequency selective channel and utilized to enable the efficient utilization of frequency resources.

Abstract: A method for a wireless local area network performed by an access point (AP) configured to communicate over a primary subchannel and a secondary subchannel. The AP transmits a frame including a quiet channel element to a receiving station. The quiet channel element indicates that the secondary subchannel is to be quieted during a quiet interval in which the AP tests the secondary subchannel for a presence of radar transmissions and the receiving station does not send any frame to the AP. The quiet channel element includes an AP quiet mode field indicating whether a communication to the AP is allowed within the primary subchannel during the quiet interval. The primary subchannel and the secondary subchannel are quieted during the quiet interval if the AP quiet mode field indicates the communication to the AP is not allowed with the primary subchannel during the quiet interval.

Abstract: The present invention relates to a method and apparatus for transmitting a frame in a wireless LAN system. An access point (AP) receives a single orthogonal frequency division multiplexing (OFDM) symbol from each of a plurality of stations (STA) and a single-tone request to send (sRTS) frame through a single subcarrier, selects STAs for performing uplink (UL) multiuser (MU)-multiple input multiple output (MIMO) transmission, and transmits to the plurality of STAs a single-tone clear to send (sCTS) frame allocated to the same subcarrier as a subcarrier to which the sRTS frames received from the selected STAs are allocated.

Abstract: A method of transmitting channel management information by an access point (AP) in a wireless local area network and configured to communicate via a primary subchannel and a secondary subchannel is provided. The method includes: transmitting a frame including a quiet channel element, the quiet channel element including a quiet mode field indicating whether a communication to the AP is allowed via part or all of the primary subchannel during a quiet interval, the quiet interval being an interval during which no transmission occurs in the secondary channel; and performing communications using the part or all of the primary subchannel, if the quiet mode field is set to a value that indicates the communication to the AP is allowed to communicate via the part or all of the primary subchannel during the quiet interval.

Abstract: A method, performed by a transceiver, is described. The transceiver receives a null data packet announcement (NDPA) frame to initiate channel sounding and a null data packet (NDP), the NDP following the NDPA frame. A first report field including beamforming information and a second report field including signal to noise ratio (SNR) information is configured. First feedback data including the first report field and a second report field is split into a plurality of segments. The plurality of segments is transmitted in a single aggregated medium access control protocol data unit (A-MPDU) including MPDUs. A retransmission request including a segment retransmission bitmap field indicating at least one segment of the plurality of segments for retransmission is received. In response to the retransmission request, second feedback data including the at least one segment indicated by the segment retransmission bitmap field is transmitted.

Abstract: A method of dynamic frequency selection by an access point (AP) in a basic service set (BSS) in a wireless local area network is provided. The access point configured to communicate over a primary subchannel and a secondary subchannel. The method includes: transmitting a frame including a quiet element and a quiet channel element; and performing channel measurements in the quiet interval. The quiet element defines an quiet interval during which no transmission occurs, the quiet channel element indicates that the secondary subchannel is to be quieted during the quiet interval, and the quiet channel element indicates a condition under which the primary subchannel may be used during the quiet interval.

Abstract: A method and device for link adaptation in a wireless local area network system, are discussed. The method may include receiving, by a responding station, from a requesting station, a requesting Physical layer Protocol Data Unit (PPDU) for requesting a modulation and coding scheme (MCS) feedback via a plurality of spatial streams, the requesting PPDU including an MCS request (MRQ) field that is set to one to request the responding station to provide the MCS feedback; and transmitting, by the responding station, to the requesting station, the MCS feedback including a recommended MCS field and a recommended stream field. The recommended MCS field indicates a recommended MCS, the recommended stream field indicates a number of at least one recommended spatial stream, and the number of the at least one recommended spatial stream is less than a number of the plurality of spatial streams used for the requesting PPDU.

Abstract: A method of receiving a multi-user packet by a receiver in a wireless local area network system. The method includes: receiving a first group identifier (ID) management request message from a transmitter, wherein the group ID management request message includes information about at least one group ID which is intended to be allocated to the receiver for multi user-multiple input multiple output (MU-MIMO) transmission, and the information about the at least one group ID indicates each group ID and a spatial stream set position for the each group ID; transmitting a first group ID management response message to the transmitter, wherein the group ID management response message indicates admission or adjustment for allocation of the at least one group ID; and receiving at least one multi-user packet from the transmitter, wherein the multi-user packet is transmitted using MU-MIMO transmission.

Abstract: In an aspect, a method of receiving a data unit, performed by an Access Point (AP), in a Wireless LAN (WLAN) system is provided. The method includes transmitting a signal protection frame, the signal protection frame comprising a group ID field indicating a Multiple Input Multiple Output (MIMO) transmission STA group including a first station (STA) and a second STA; and, a spatial stream field indicating a number of spatial streams allocated to each of member STAs included in the MIMO transmission STA group; receiving a first preamble for a first data unit from the first STA; receiving a second preamble for a second data unit from the second STA; and simultaneously receiving the first data unit from the first STA and the second data unit from the second STA.

Abstract: A method for a channel sounding in a wireless local area network. A station receives a 20 MHz null data packet announcement (NDPA) frame and at least one duplicate 20 MHz NDPA frame. The at least one duplicate 20 MHz NDPA frame is a duplicate of the 20 MHz NDPA frame. The station also receives a null data packet (NDP) following the 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame. The bandwidth over which the 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame are transmitted is the same as a bandwidth over which the NDP is transmitted. The station transmits a report frame for the channel sounding. The 20 MHz NDPA frame and the at least one duplicate 20 MHz NDPA frame comprise bandwidth information indicating the bandwidth over which the frames are transmitted.

Abstract: A method for a channel sounding in a wireless local area network is provided. The method includes transmitting a null data packet announcement (NDPA) frame, to a plurality of receivers, the NDPA frame requesting a channel statement information feedback and announcing that a null data packet (NDP) frame is to be transmitted; transmitting the NDP frame being a basis of channel estimation for the plurality of receivers; receiving a first feedback frame from a first receiver among the plurality of receivers, transmitting a feedback poll frame to a second receiver; and, receiving a second feedback frame from the second receiver, the second feedback frame including second channel state information estimated by the second receiver. If the first receiver fails to perform the channel estimation, the first feedback frame is a null feedback frame. The null feedback frame is a feedback frame not including channel state information.

Abstract: A channel sounding method in a wireless local area network (WLAN) system is provided. The method, performed by a transmitter, includes transmitting a null data packet announcement (NDPA) frame to a receiver to initiate channel sounding, and transmitting a null data packet (NDP) to the receiver and receiving a feedback frame. The feedback frame includes a plurality of segment frames and a channel feedback report. The channel feedback report is split into a plurality of feedback segments. Each of the plurality of feedback segments is respectively included in each of the plurality of segment frames. Each of the plurality of segment frames includes a first-segment subfield indicating whether the each of the plurality of feedback segments included is a first segment and a remaining-segment subfield indicating the number of remaining feedback segments.

Abstract: Method and apparatus of network traffic offloading is disclosed. Network traffic offloading method may include receiving a first network traffic offloading frame from a base station in a cellular network, the first network traffic offloading frame comprising a frame type instructing a scanning start by broadcasting an advertising frame, traffic information indicating traffic expected to be offloaded by the base station and a transmission configuration indicating a period and a duration to transmit the advertising frame, broadcasting the advertising frame based on the transmission configuration to scan at least one access point (AP), receiving at least one invitation frame from the at least one AP and transmitting a probe request frame to an AP selected among the at least one AP to associate with the selected AP.

Abstract: A channel sounding method in a wireless local area network (WLAN) system is provided. The method, performed by a transmitter, includes transmitting a null data packet announcement (NDPA) frame to a receiver to initiate a channel sounding procedure; transmitting a null data packet (NDP) to the receiver and receiving a feedback frame. The feedback frame includes a plurality of segment frames and a channel feedback report. The channel feedback report is split into a plurality of feedback segments. Each of the plurality of feedback segments is respectively included in each of the plurality of segment frames. The each of the plurality of segment frames includes a first-segment subfield indicating whether the each of the plurality of feedback segment included is a first segment and a remaining-segment subfield indicating the number of remaining feedback segments.

Abstract: Method and apparatus of transmitting PLCP header for sub 1 GHz communication is disclosed. A method of transmitting a physical layer convergence protocol (PLCP) header may comprise generating a short training field (STF) sequence over 1 orthogonal frequency division multiplexing (OFDM) symbol, transforming the STF sequence to repeated waveform patterns in time domain and transmitting the PLCP header comprising the STF sequence, wherein the STF sequence may be a sequence transformed to repeated waveform patterns in time domain by inverse discrete Fourier transform (IDFT).

Abstract: A method and wireless apparatus are described, whereby a transceiver receives a null data packet announcement (NDPA) frame from a transmitter to initiate channel sounding, and receives a null data packet (NDP) from the transmitter, the NDP following the NDPA frame. A first report field is configured to include beamforming information, and a second report field is configured to include signal to noise ratio (SNR) information. A determination is made as to whether feedback data including the first report field and the second report field is transmitted in a single feedback frame or a plurality of feedback frames. If the feedback data is determined to be transmitted in the plurality of feedback frames, the feedback data is split into a plurality of segments, which is transmitted in a single aggregated medium access control protocol data unit (A-MPDU) including a plurality of MPDUs.