Abstract: In a method for generating a data unit for transmission via a communication channel, wherein the data unit conforms to a first communication protocol, a preamble of the data unit is generated. The preamble includes a first field having information that indicates a duration of the data unit, the first field being formatted such that the first field is decodable by a receiver device that conforms to a second communication protocol but does not conform to the first communication protocol to determine the duration of the data unit based on the first field. Additionally, the preamble is formatted such that a portion of the preamble is decodable by a receiver device that conforms to a third communication protocol but does not conform to the first communication protocol. Also, the preamble is formatted such that a receiver device that conforms to the first communication protocol can determine that the data unit conforms to the first communication protocol.

Abstract: A method in a communication network includes obtaining descriptions of a plurality of communication channels each communication channel associated with a different one of a plurality of receivers; and generating a plurality of steering vectors, one for each of the plurality of receivers, using the descriptions of the plurality of communication channels; wherein each steering vector is used to transmit data to a corresponding one of the plurality receivers via a plurality of antennas and over a corresponding one of the communication channels simultaneously and wherein each steering vector is used to communicate data on a different one of the plurality of communication channels, and wherein each steering vector is generated to reduce interference on a corresponding communication channel caused by simultaneous transmission of data on other communication channels.

Abstract: An access point including a medium access control module and an acknowledgment generating module. The medium access control module designates a predetermined time period to communicate with a first set of client stations, and instructs a second set of client stations to transmit data at a time other than the predetermined time period. The acknowledgment generating module generates a plurality of acknowledgements in response to receiving data from the first set of client stations during the predetermined time period. The medium access control module aggregates the plurality of acknowledgements in a single aggregated frame. The single aggregated frame includes a plurality of sub-frames. Each sub-frame of the single aggregated frame includes one of the plurality of acknowledgements. The medium access control module transmit the single aggregated frame to the first set of client stations during the predetermined time period.

Abstract: In one or more aspects data packets are iteratively transmitted to a receiver using predefined spatial mapping matrices, channel estimates are received from the receiver responsive to iteratively transmitted data packets, and one of the predefined spatial mapping matrices is selected for transmitting additional data packets to the receiver based on the received channel estimates.

Abstract: In generating a data unit for transmission via a communication channel, a preamble of the data unit is generated, including i) generating a set of training fields, and ii) mapping each training field in the set of training fields to a plurality of space-time streams. When the set of training fields consist of four training fields, each training field in the set of training fields is mapped to four space-time streams according to a first space-time stream mapping matrix. When the set of training fields consists of six training fields, each training field in the set of training fields is mapped to six space-time streams according to a second space-time stream mapping matrix, wherein the first space-time stream mapping matrix is not a submatrix of the second space-time stream mapping matrix. A data portion of the data unit is generated so that a receiver device can receive the data portion via a corresponding number of space-time streams using channel information derived from the set of training fields.

Abstract: One or more beamsteering matrices are applied to one or more signals to be transmitted via multiple antennas. After the one or more beamsteering matrices are applied to the one or more signals, the plurality of signals is provided to a plurality of power amplifiers coupled to the multiple antennas. Signal energies are determined for the plurality of signals provided to the plurality of power amplifiers, and relative signal energies are determined based on the determined signal energies. Output power levels of the plurality of power amplifiers are adjusted based on the determined relative signal energies.

Abstract: A preamble, first and second portions of a data payload of a single data unit, and a midamble included between the first and second portions are generated. The midamble includes calibration information, and is based on a maximum number of space-time streams of a communication channel. A network interface of a communication device generates the preamble, the first and second portions of the data payload, and the midamble. A preamble, first and second portions of a data payload of a single data unit, and a midamble are received. The midamble includes calibration information, and is based on a maximum number of space-time streams. A first and/or a second characteristic is updated based on the midamble. A network interface of a communication device receives the preamble, the first and second portions of the data payload, and the midamble; and updates the first or the second characteristic based on the midamble.

Abstract: In a wireless communication system wherein communication devices exchange information utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code, a physical layer (PHY) data unit that conforms to a second format and is for transmitting PHY control information is generated. Generating the PHY data unit includes generating a first portion of the PHY data unit to indicate the PHY data unit conforms to the second format, wherein the first portion of the PHY data unit includes an STF spread with a second spread code different than the first spread code. A second portion of the PHY data unit is generated according to the second format, wherein the second portion of the PHY data unit omits header fields specified by the first format.

Abstract: One or more beamsteering matrices are applied to one or more signals to be transmitted via multiple antennas. After the one or more beamsteering matrices are applied to the one or more signals, the plurality of signals is provided to a plurality of power amplifiers coupled to the multiple antennas. Signal energies are determined for the plurality of signals provided to the plurality of power amplifiers, and relative signal energies are determined based on the determined signal energies. Output power levels of the plurality of power amplifiers are adjusted based on the determined relative signal energies.

Abstract: In a method for determining a transmit steering matrix for use in transmission of an information signal from a first communication device to at least one second communication device, a subset of antennas of the at least one second communication device is selected from a plurality of different subsets of the antennas of the at least one second communication device, wherein selecting the subset of antennas is for developing the steering matrix for transmit beamforming from the first communication device to the least one second communication device. The steering matrix is developed i) based on training signals received via the selected subset of the antennas of the at least one second communication device, and ii) assuming that only the selected subset of the antennas of the at least one second communication device will be utilized by the at least one second communication device when receiving the information signal.

Abstract: A modulation coding scheme (MCS) is selected i) from a first set of MCSs when the PHY data unit is to be transmitted using a first channel bandwidth, and ii) from a second set of MCSs when the PHY data unit is to be transmitted using a second channel bandwidth. The first set of MCSs corresponds to i) a number of spatial streams, and ii) the first channel bandwidth, the second set of MCSs corresponds to i) the number of spatial streams, and ii) the second channel bandwidth. The second set of MCSs excludes one or more MCSs in the first set of MCSs that will result in a padding-related constraint not being met when the second channel bandwidth is to be used. Information bits are encoded according to the selected MCS, and modulated according to the selected MCS.

Abstract: An access point including a first transmitter and a second transmitter. The first transmitter is configured to (i) during a first window, transmit a first data stream to a first client station, and (ii) during a second window, transmit a second data stream to a second client station. The second transmitter is configured to: during the first window and while the first transmitter transmits the first data stream to the first client station, transmit a third data stream to a third client station; during a first portion of the second window and while the first transmitter is transmitting the second data stream to the second client station, refrain from transmitting a fourth data stream to a fourth client station; and subsequent to the first transmitter completing the transmission of the second data stream and during a second portion of the second window, transmit the fourth data stream to the fourth client station.

Abstract: A bi-directionally calibrated beamforming technique for use in a MIMO wireless communication system includes a transmitter communicating a calibration initiation signal to a receiver requesting the receiver send a non-sounding packet containing an estimated description of the forward channel. The receiver also sends a sounding packet to the transmitter. The transmitter determining a partial or full estimated description of a reverse channel based on the received non-sounding packet and/or the receiving sounding packet. The transmitter further determines one or more transmitter correction matrices from receiving estimated description of the forward channel and the partial or full estimated description of the reverse channel. The transmitter sending the partial or full estimated description of the reverse channel to the receiver, which determines one or more receiver correction matrices.

Abstract: A first communication device receives a non-sounding data unit from a second communication device that does not support beamforming training procedures. The first communication device develops an estimate of a reverse channel via which the non-sounding data unit traveled based on the non-sounding data unit. The first communication device develops a transmit beamforming matrix based on the estimate of the reverse channel, the transmit beamforming matrix for the first communication device to utilize when transmitting via a forward channel.

Abstract: Methods and apparatus are provided for adaptively selecting a communications mode in high frequency systems. A first dual-mode device having capabilities of using two or more high frequency communications modes, such as OFDM and SC modulation, may transmit a signal to a second dual-mode device with the same capabilities. The second dual-mode device may compute a channel characteristic associated with a high frequency communications channel and select an optimal high frequency communications mode. The second dual-mode device may transmit information indicative of the channel characteristic or the selected communications mode to the first dual-mode device. The first dual-mode device may select and operate using the optimal high frequency communications mode based on the information received from the second dual-mode device. The first and second dual-mode devices may communicate using the selected high frequency communications mode.

Abstract: In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, information bits to be included in the PHY data unit are encoded using a forward error correction (FEC) encoder. Also, the information bits are encoded according to a block coding scheme, where m copies of each bit are included in the information bits, and one or more bits in the m copies of each bit are flipped. The information bits are mapped to a plurality of constellation symbols, and a plurality of orthogonal frequency division multiplexing (OFDM) symbols are generated to include the plurality of constellation symbols. The PHY data unit is generated to include the plurality of OFDM symbols.

Abstract: A modulation coding scheme (MCS) is selected from i) a first set of MCSs when the selected channel bandwidth is a first channel bandwidth, or ii) a second set of MCSs when the selected channel bandwidth is a second channel bandwidth, wherein the first set of MCSs is different than the second set of MCSs, and the second set of MCSs excludes MCSs from the first set of MCSs that will result in a padding-related constraint not being met when the second channel bandwidth is to be used. Information bits are interleaved, which includes applying a frequency rotation. The information bits are modulated according to the selected MCS. A plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols are generated using the modulated information bits.

Abstract: Systems and methods for removing DC offset from a signal are provided. A radio frequency signal is received at a receiver. The radio frequency signal is converted into a digital signal including a periodic component with a period. A carrier frequency offset is removed from the digital signal to generate a frequency-shifted digital signal. The frequency-shifted digital signal is filtered to remove a DC offset in the digital signal. The filtering includes applying a moving average filter matched to the period to remove the periodic component from the frequency-shifted digital signal. The moving average filter generates a set of average values based on the frequency-shifted digital signal. The filtering also includes taking a difference between consecutive values of the set of average values to determine the DC offset, where the DC offset is introduced at the receiver.

Abstract: In a method for beamforming in a multiple input multiple output (MIMO) communication system, a data unit is received from a communication device via a MIMO communication channel, and it is determined whether the data unit satisfies one or more selection criteria. Further, when it is determined that the data unit satisfies the one or more selection criteria, the data unit is selected to be used in developing a steering matrix for transmitting data units to the communication device.

Abstract: A system and method of extracting data from data packets transmitted over a wireless network includes receiving a data packet having a preamble portion and a payload portion. The preamble portion is cross correlated with a first known spreading sequence to generate a first timing signal and the preamble portion is cross correlated with a second known spreading signal to generate a frame timing signal. An impulse is detected in the first timing signal and a first timing parameter is set based upon the detected impulse in the first timing signal. An impulse is detected in the frame timing signal and a frame timing parameter is set based upon the detected impulse in the frame timing signal. Data is extracted from the received payload portion according to the first timing parameter and the frame timing parameter.