Abstract: The present invention relates to a method for transmitting and receiving a frame performed by an AP in a wireless communication system. The method includes the steps of: transmitting a PST message providing instructions to transmit a frame to at least one STA; and receiving frames from a first STA and a second STA. The PST message includes first subband information indicating a first subband in which a first frame is transmitted from the first STA and second subband information indicating a second subband in which a second frame is transmitted from the second STA.

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: 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 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: Provided are a method and device for processing an uplink (UL) signal in a WLAN system. An access point (AP) receives a request to send (RTS) frame from one station (STA) among a plurality of STAs, transmits a group identifier (ID) of a group to which STAs for performing UL multi user multiple-input multiple-output (MU-MIMO) transmission together with the one STA, among group IDs of a group to which the one STA belongs, and receives UL signals from the STAs which perform the UL MU-MIMO transmission such that the received UL signals are processed.

Abstract: Disclosed are a method and device for transmitting a frame. The method for transmitting a frame includes a step of generating A-MPDU (aggregate MAC protocol data unit) and a step of transmitting A-MPDU. The A-MPDU includes a first AMPDU subframe and a second A-MPDU subframe, wherein the first A-MPDU subframe includes a data block, and the second AMPDU subframe includes an FEC (Forward Error Correction) coding block which is additionally used in the decoding of the data block. Thus, the STA is capable of preventing unnecessary power consumption of STA by selectively determining whether FEC information is received according to whether an error occurred in the decoded data.

Abstract: A method for reporting channel information in a wireless local area network system is provided. The method includes receiving a data block for requesting a modulation and coding scheme (MCS) feedback from a requesting station, the data block including a data field and a stream indicator indicating a number of at least one spatial stream in the data field; determining, the MCS feedback based on the data block; and, transmitting the MCS feedback to the requesting station, the MCS feedback including a recommended MCS and a recommended stream indicator indicating a number of at least one recommended spatial stream. The number of the at least one recommended spatial stream in the MCS feedback is equal or less than the number of the at least one spatial stream in the data block.

Abstract: The present invention relates to a method for transmitting a frame, which is performed by a transmission station in a wireless LAN system that supports frame transmission and reception on the basis of a first physical layer and a second physical layer. The method comprises the steps of: transmitting a request-to-send (RTS) to a reception station through the first physical layer of the transmission station; receiving, by the reception station, a first clear-to-send (CTS) frame transmitted through the first physical layer of the reception station in response to the RTS frame; and transmitting a second CTS frame through the second physical layer of the transmission station, then transmitting a data frame through the first physical layer of the transmission station.

Abstract: The present invention relates to a method and device for channel measurement in a wireless LAN system. A station (STA) receives a plurality of sounding frames from an access point (AP), estimates the plurality of sounding frames in order to generate long-term channel state information (LCSI), provides the generated LCSI to the AP as feedback, and receives from the AP a group identifier (ID) management frame comprising information on a group ID determined on the basis of the LCSI.

Abstract: A layered channel access method of a Group Representative-station (GR-STA) in a Wireless Local Area Network (WLAN) system is provided. The method includes receiving a management, including setting information indicative of a first phase and a second phase frame, from an Access Point (AP), receiving a first radio frame from the AP or accessing a channel and sending a second radio frame to the AP during the first phase indicated by the setting information, and receiving a third radio frame from an affiliated STA of a group to which the GR-STA belongs or accessing a channel and sending a fourth radio frame to at least one STA of the group to which the GR-STA belongs during the second phase indicated by the setting information.

Abstract: A method of communication based on a receive chain control, performed by a receiver, in a wireless local area network is provided. The method includes: receiving a frame from a transmitter, the frame indicating a multi receive chain operation, activating at least one receive chain, each receive chain processing a received signal transmitted through each spatial stream, and receiving at least one data field from the transmitter through the at least one activated receive chain.

Abstract: The present invention relates to a method of determining a Modulation and Coding Scheme (MCS) feedback in a Wireless Local Area Network (WLAN) system, including an MCS FeedBack (MFB) responder receiving a first frame, including a request message requesting to send the MFB, from an MFB requester and the MFB responder sending the MFB, including a recommended MCS value, to the MFB requester. The recommended MCS value is derived with reference to at least one of unsolicit type information indicative of a type of the MFB, transmit type information indicative of a transmission type of data, coding type information indicative of a coding scheme applied to the data, a group ID indicative of a group of target stations (STAs) to which the data will be transmitted, and MFB bandwidth information indicative of a bandwidth of a channel.

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 multiple-input multiple-output (MIMO) communication method and apparatus are provided. A MIMO communication apparatus includes a selected beamforming vector determining unit to determine a selected beamforming vector corresponding to a selected user, a performance information generating unit to generate performance information corresponding to where a non-selected beamforming vector is allocated to a non-selected user, and an additional beamforming vector selecting unit to select an additional beamforming vector corresponding to the non-selected user based on the performance information.

Abstract: In a multi-user multiple input multiple output (MIMO) communication system using the same radio resource, a unitary matrix may be generated to remove interference signals and enhance a transmission capacity. The unitary matrix may be used for precoding. Vectors included in the unitary matrix may have a most similar direction to precoding vectors of target terminal devices and may be orthogonal to each other.

Abstract: A base station apparatus and method of transmission of dynamic feedback channel information in a MIMO system. The base station apparatus includes a first channel state information receiving unit to receive a first channel state information; a receiving terminal selection unit to select at least one receiving terminal to receive data from among a plurality of terminals; a quantization length determination unit to independently determine a second quantization length of the selected receiving terminal; a quantization length transmission unit to transmit the second quantization length to the selected e receiving terminal; a second channel state information receiving unit to receive second channel state information from the selected receiving terminal; and a data transmission unit to transmit data to the selected receiving terminal using a plurality of transmission antennas of a base station based on the second channel state information.

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 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 for reporting channel information in a wireless local area network system is provided. The method includes receiving a data block for requesting a modulation and coding scheme (MCS) feedback from a requesting station, the data block including a data field and a stream indicator indicating a number of at least one spatial stream in the data field; determining, the MCS feedback based on the data block; and, transmitting the MCS feedback to the requesting station, the MCS feedback including a recommended MCS and a recommended stream indicator indicating a number of at least one recommended spatial stream. The number of the at least one recommended spatial stream in the MCS feedback is equal or less than the number of the at least one spatial stream in the data block.

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.