Abstract: Methods and devices for transmitting or receiving data in a wireless local area network are provided. The method in one embodiment includes transmitting, by a transmitter, a first long training field (LTF) to a receiver; transmitting, by the transmitter, a very high throughput (VHT)-SIG-A field to the receiver; transmitting, by a transmitter, a second LTF for multiple input multiple output (MIMO) channel estimation to the receiver; transmitting, by the transmitter, a VHT-SIG-B field to the receiver; and transmitting, by the transmitter, a data field to the receiver, wherein the first LTF, the VHT-SIG-A field, the second LTF, the VHT-SIG-B field and the data field are sequentially transmitted, and wherein the second LTF and the data field are mapped to at least one spatial stream based on a mapping matrix but the first LTF and the VHT SIG-A field are not mapped to the at least one spatial stream.

Abstract: A method for transmitting and receiving uplink signals using an optimized rank 3 codebook is disclosed. The optimized rank 3 codebook includes 6 precoding matrix groups, each of which has 1 variable having an amplitude of 1. Preferably, the optimized 4Tx rank 3 codebook has 12 precoding matrix, two precoding matrixes are selected from each the above 6 precoding matrix groups considering chordal distance and the number of precoding matrix.

Abstract: A method and terminal apparatus are described for allocating resources for transmitting a signal in a multiple-input multiple-output (MIMO) wireless communication system. An uplink signal is transmitted using L layers at a terminal in a multiple-input multiple-output (MIMO) wireless communication system. Modulation symbols are generated by modulating output bit sequences of an interleaver matrix by a unit of log2 Q bits. Q is a modulation order, and each of the output bit sequences has a size of L·log2 Q bits. The modulation symbols are mapped to the L layers and transmitted by using the L layers. The output bit sequences are generated by reading out entries of the interleaver matrix, column by column.

Abstract: The present description relates to a wireless communication system, and more particularly, to a method and apparatus for uplink multiple input multiple output (MIMO) transmission. A method for performing an uplink MIMO transmission according to one embodiment of the present invention comprises the following steps: transmitting, from a first subframe, a first data block and a second data block through a first HARQ process and a second HARQ process, respectively; receiving, at a second subframe, uplink scheduling control information on the first data block and control information which indicates inactivation of the second data block; setting HARQ feedback information on the second data block to an ACK state; and performing retransmission of the first data block from a third subframe on the basis of the uplink scheduling control information on the first data block. Retransmission of the second data block may not be performed until uplink scheduling control information on the second data block is received.

Abstract: A method and apparatus for allowing a UE to transmit uplink signals using a MIMO scheme are disclosed. In order to maintain good Peak power to Average Power Ratio (PAPR) or Cubic Metric (CM) properties when the UE transmits uplink signals using the MIMO scheme, the UE uses a precoding scheme based on a precoding matrix established in a manner that one layer is transmitted to each antenna in specific rank transmission.

Abstract: A method of transmitting a Physical Layer Convergence Procedure (PLCP) frame in a Very High Throughput (VHT) Wireless Local Area Network (WLAN) system includes generating a MAC Protocol Data Unit (MPDU) to be transmitted to a destination station (STA), generating a PLCP Protocol Data Unit (PPDU) by adding a PLCP header, including an L-SIG field containing control information for a legacy STA and a VHT-SIG field containing control information for a VHT STA, to the MPDU, and transmitting the PPDU to the destination STA. A constellation applied to some of Orthogonal Frequency Division Multiplex (OFDM) symbols of the VHT-SIG field is obtained by rotating a constellation applied to an OFDM symbol of the L-SIG field.

Abstract: A method for transmitting, by a base station, configuration information for a reference signal for channel measurement. The method according to one embodiment includes transmitting, to a user equipment, first resource information for indicating a first pattern, first subframe information for indicating a first subframe, second resource information for indicating a second pattern, and second subframe information for indicating a second subframe. The first subframe information includes information indicating a first periodic interval, and the second subframe information indicates information indicating a second periodic interval. Each of the first and second subframes is comprised of two slots—slot 0 and slot 1, and each of the first and second reference signal time-frequency resources is within two OFDM symbols other than OFDM symbols 0, 1, 2, and 3 of the slot 0 and other than OFDM symbols 0, 1, and 3 of the slot 1.

Abstract: A method and a station are described for transmitting a data frame in a wireless local area network (WLAN). The station obtains a transmission opportunity (TXOP) and transmits, during the TXOP, a preceding data unit of a plurality of data units comprising a control field indicating a selected bandwidth for the preceding data unit. The station selects a transmit bandwidth parameter of a non-initial data unit of the plurality of data units from available bandwidth parameters. The available bandwidth parameters include a first available bandwidth parameter which is same as a transmit bandwidth parameter of the preceding data unit of the plurality of data units and a second available bandwidth parameter which is narrower than a transmit bandwidth parameter of the preceding data unit. The station transmits, during the TXOP, the non-initial data unit, which comprises a control field indicating a selected bandwidth for the non-initial data unit.

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 power saving in a wireless local area network, and a wireless apparatus therefore are discussed. The method according to one embodiment includes acquiring a transmission opportunity (TXOP), receiving a signal field, the signal field including a group identifier, a number indicator and a power saving indicator, the group identifier indicating a group of recipients, the number indicator indicating a number of spatial streams, the power saving indicator indicating that the transmitting device allows the wireless device to enter a doze state. The method according to the embodiment further includes entering the doze state until the end of the TXOP if the power saving indicator indicates an allowance of entering the doze state during the TXOP, the wireless device is a member of the group of recipients, and the number of spatial streams to be received by the wireless device is equal to zero.

Abstract: A method and apparatus are described for transmitting data. The method includes generating, by an access point (AP), a Physical Layer Protocol Data Unit (PPDU) including a signal field and a data field, and transmitting, by the AP, the PPDU to a station. The signal field includes a reception target indicator and an identifier field. The reception target indicator indicates whether a target of the PPDU is the AP or the station. The identifier field includes a local AP identifier identifying the AP when the reception target indicator indicates that the target of the PPDU is the station.

Abstract: A method of transmitting modulation and coding scheme (MCS) feedback (MFB) in a wireless local area network system is provided. The method is performed by a first station and includes receiving, from a second station, a physical layer convergence procedure (PLCP) protocol data unit (PPDU), estimating a MFB based on the PPDU and transmitting, to the second station, feedback information including a MFB field and a MFB type field. The MFB field includes the MFB and the MFB type field indicates whether or not the MFB is in response to a MFB request (MRQ) of the second station.

Abstract: The present application discloses a method in which a base station transmits a reference signal sequence in a wireless communication system. In detail, the method comprises the steps of: generating a pseudo-random sequence using a first m-sequence and a second m-sequence; generating the reference signal sequence using the pseudo-random sequence; and transmitting the reference signal to a mobile station via antenna ports different from one another. The second m-sequence has an initial value containing parameters for discriminating reference signal sequences among users.

Abstract: A method for transmitting and receiving uplink signals using an optimized rank 3 codebook is disclosed. The optimized rank 3 codebook includes 6 precoding matrix groups, each of which has 1 variable having an amplitude of 1. Preferably, the optimized 4Tx rank 3 codebook has 12 preceding matrix, two precoding matrixes are selected from each the above 6 precoding matrix groups considering chordal distance and the number of precoding matrix.

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: A method for retransmitting data in synchronous Hybrid Automatic Repeat reQuest (HARQ) to support Multiple Input Multiple Output (MIMO) is disclosed. The method includes transmitting a plurality of unit data blocks to a receiver, receiving from the receiver a control channel signal including first feedback information indicating whether the transmission of the plurality of unit data blocks is successful, and retransmitting at least one of the plurality of unit data blocks according to a predetermined order, each unit data block in one Transmission Time Interval (TTI), if a rank is 1 and the first feedback information indicates that the transmission of the plurality of unit data blocks is failed.

Abstract: A method of transmitting PMI (precoding matrix indicator) information in an uplink MIMO system is disclosed.

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 power saving in a wireless local area network. The method according to one embodiment includes acquiring, by a wireless device, a transmission opportunity (TXOP); and receiving a signal field from the transmitting device. A group identifier indicates recipients, a number indicator indicates spatial streams, and a power saving indicator indicates that the transmitting device is allowed to enter a doze state during the TXOP. The method according to the embodiment further includes determining, by the wireless device, whether a first condition or a second condition is satisfied. The first condition is satisfied if the power saving indicator indicates an allowance, the wireless device is a recipient indicated by the group identifier, and the number of spatial streams is equal to zero. The second condition is satisfied if the power saving indicator indicates an allowance, and the wireless device is not a recipient indicated by the group identifier.

Abstract: The present application discloses a method in which a base station transmits a reference signal sequence in a wireless communication system. In detail, the method comprises the steps of: generating a pseudo-random sequence using a first m-sequence and a second m-sequence; generating the reference signal sequence using the pseudo-random sequence; and transmitting the reference signal to a mobile station via antenna ports different from one another. The second m-sequence has an initial value containing parameters for discriminating reference signal sequences among users.