Abstract: Systems and techniques relating to wireless communications are described. A described system includes circuitry configured to generate, in accordance with a clock signal, a first baseband signal for transmission over a wireless channel, one or more first preamble symbols of the first baseband signal are based on a pre-determined preamble sequence when a first clock frequency is used in the clock signal. The described system includes circuitry configured to generate, in accordance with the clock signal, a second baseband signal for transmission over the wireless channel, one or more second preamble symbols of the second baseband signal are based on the pre-determined preamble sequence, the one or more second preamble symbols have a longer duration than the one or more first preamble symbols when a second clock frequency is used in the clock signal. The second clock frequency is lower than the first clock frequency and is used to extend a wireless communication range of the wireless channel.

Abstract: A first wireless device including a receiver and a transmitter. The receiver includes a channel estimation module configured to receive, from a second wireless device over a communication channel, a training packet and estimate a quality of the communication channel based on the training packet, and a modulation and coding scheme (MCS) determination module configured to determine an MCS based on one or more of the training packet and the estimated quality of the communication channel. The transmitter is configured to transmit, to the second wireless device over the communication channel, an indication of the MCS determined by the MCS determination module.

Abstract: Example apparatus and methods provide multiple power modes for an 802.11N radio. In one embodiment, an apparatus includes a radio frequency (RF) unit including a transmit circuit configured to transmit RF signals to an antenna, and a receive circuit configured to receive RF signals from the antenna. The apparatus may also include a baseband unit configured to analyze RF signals received by the RF unit. The baseband unit may also be configured to provide signal strength information concerning the RF signals received by the RF unit and/or channel quality information concerning a channel associated with the RF signals received by the RF unit. The apparatus may also include a MAC logic configured to control the RF unit to operate in either a power save mode or in a high power mode based on the signal strength information or the channel quality information provided by the baseband unit.

Abstract: Systems and methods for detecting data in a received multiple-input-multiple-output signal are provided. First, second, and third signals are received and form a vector y. The received signals are associated with first, second, and third data values that form a vector x. A channel matrix (H) is received, and a QR decomposition of the channel matrix is performed, such that H=QR. The vector y is transformed into a vector z according to z=QHy. A distance value between the rector z and the vector x is determined for each possible third data value. A nearest constellation point is calculated based on a first of the possible third data values. The calculating step is repeated for each of the possible third data values to generate a set of constellation point triplets. The distance values are determined using the set of constellation point triplets.

Abstract: Systems and methods are provided for processing a payload portion of a received signal in a single carrier mode or a multiple carrier mode based on a portion of the received signal. A single carrier signaling portion is received at a first rate, and whether the payload portion of the signal is a single carrier signal or a multiple carrier signal is detected from the received single carrier signaling portion. The payload portion of the received signal is received at the first rate and demodulated in a single carrier mode if the detecting determines that the payload portion of the received signal is a single carrier signal, and the payload portion of the received signal is demodulated in a multiple carrier mode if the detecting determines that the payload portion of the received signal is a multiple carrier signal.

Abstract: A method in a wireless communication system having a forward channel corresponding to transmissions from a first device to a second device, and a reverse channel corresponding to transmissions from the second device to the first device, includes initiating, at the first device, a first update of a steering matrix. The steering matrix is used to beamform transmissions on the forward channel. The method also includes monitoring, at the first device, a plurality of reverse channel estimates corresponding to the reverse channel, determining, at the first device, a metric indicative of a rate of change in the reverse channel based on the plurality of reverse channel estimates, and initiating, at the first device, a second update of the steering matrix based on a comparison between (i) the metric indicative of the rate of change in the reverse channel and (ii) a threshold.

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 one or more embodiments, in a communications terminal an estimated channel matrix is constructed based on a codebook. A modified estimated channel matrix is calculated based on both the estimated channel matrix and a protection matrix, and a channel submatrix is selected from the modified estimated channel matrix. A selection matrix is calculated from the channel submatrix, and fed back to be used in generating a steering matrix.

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: In a beamforming method, one or more compensation factor sets are applied to antennas of a first communication device. A modulation and coding scheme (MCS) for communicating with a second communication device is selected while applying a first compensation factor set to the antennas of the first communication device. For each of the one or more compensation factor sets, (i) a steering matrix is developed based on a data unit received at the first communication device from the second communication device, (ii) one or more data units are transmitted from the first communication device to the second communication device while applying the steering matrix and the compensation factor set to the first plurality of antennas, and (iii) a channel performance indicator is determined based on the one or more data units. A compensation factor set to be used in subsequent beamforming operations is selected based on the channel performance indicator.

Abstract: In a method for reducing interference in a first wireless communication network and a second wireless communication network, a first access point (AP) device of the first wireless communication network coordinates with a second AP device of the second wireless communication network with respect to utilizing transmit beamforming at the first AP device and transmit beamforming at the second AP device for the purpose of reducing interference in the first wireless communication network and the second wireless communication network. Based on coordinating with the second AP device, the first AP device uses a beamforming matrix to transmit, via a multiple input, multiple output (MIMO) communication channel, to one or more first stations in the first wireless communication network for mitigating interference between the first wireless communication network and the second wireless communication network.

Abstract: A method for processing a preamble of a data packet, received via a communication channel, using a pair of complementary sequences, wherein a sum of out-of-phase aperiodic autocorrelation coefficients of the pair of complementary sequences is zero, and wherein the preamble includes a first field that provides synchronization information and a second field that provides channel estimation information, includes at least one of (i) correlating a received signal corresponding to the preamble with at least one sequence of the pair of complementary sequences to generate a plurality of respective correlation signals, or (ii) autocorrelating the received signal to generate an autocorrelation signal. The method also includes determining a cover code in the preamble using at least one of (i) the plurality of respective correlation signals, or (ii) the autocorrelation signal. The method also includes using the cover code to decode the preamble.

Abstract: A first preamble for a first data unit includes a first long training field and a first signal field modulated according to a first technique. The first data unit is generated according to a first data unit format and includes the first preamble. A second preamble, generated for a second data unit, includes a second signal field and a second long training field. Information in the second signal field is repeated and/or the second long training field is generated so that a duration of the second long training field is longer than a duration of the first long training field. A portion of the second signal field is modulated according to a second technique or a portion of the second long training field is modulated according to the second technique to signal to a receiver that the second data unit is formatted according to a second data unit format.

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: Systems, methods, and other embodiments associated with a hybrid beamforming architecture are described. According to one embodiment, an apparatus includes a beamforming mode detection logic configured to select a beamforming mode based, at least in part, on a packet received from a wireless device. The apparatus also includes a beamformee unit and a beamformer unit. The beamformee unit is configured to derive steering information from channel related information in the packet. The beamformer unit is configured to provide weights from a steering matrix to a transmitter performing transmit beamforming on a subsequent packet being transmitted to the wireless device. The beamforming mode detection logic routes at least part of the packet to one or both of the beamformee unit and the beamformer unit based, at least in part, on the selected beamforming mode.

Abstract: Systems and methods are provided for computing soft information for digital information based on a received signal, where the received signal suffers from noise and interference. A receiver that decodes the received signal may estimate channel information, such as the channel gain, associated with the interfering source. The receiver may also obtain modulation information through a backbone network or by decoding control information transmitted by the interfering source. Using the modulation information and the channel information, the receiver may estimate the effect that interference has on the received signal, and may compute soft information (e.g., a log-likelihood ratio) for the digital information.

Abstract: A method for determining a phase of each of a plurality of transmitting antennas in a multiple input and multiple output (MIMO) communication system includes: calculating, for first and second ones of the plurality of transmitting antennas, a value based on first and second groups of channel gains, the first group including channel gains between the first transmitting antenna and each of a plurality of receiving antennas, the second group including channel gains between the second transmitting antenna and each of the plurality of receiving antennas; and determining the phase of each of the plurality of transmitting antennas based on at least the value.

Abstract: In a method for generating a physical layer (PHY) data unit for transmission via a communication channel, a first preamble portion and a data portion of the data unit is generated. The first preamble portion includes one or more long training fields. The first preamble portion and the data portion are modulated using a plurality of orthogonal frequency division multiplexing (OFDM) symbols. Symbol duration of each OFDM symbol is at least 8 ?s. The data unit is generated to include the plurality of OFDM symbols.

Abstract: A beamforming training (BFT) data unit for transmission via a communication channel in a wireless personal area network is generated, and in particular, is for transmitting beamforming training information. A physical layer header and first BFT data are encoded using block encoding to generate a first block. Second BFT data are encoded using block encoding to generate a second block. The BFT data unit is generated with a fixed-length payload, such that the BFT data unit includes only i) a preamble, ii) the first block, and iii) the second block.

Abstract: In a method for reducing interference in wireless communications, a beamforming matrix is determined at a first communication device based on an estimate of a multiple input, multiple output (MIMO) communication channel between the first communication device and a second communication device. Both the first communication device and the second communication device belong to a first wireless network. Alternatively, the beamforming matrix may be generated based on the estimate of the MIMO communication channel and received at the first communication device. The beamforming matrix is used at the first communication device for the purpose of reducing interference to a second wireless network. where the interference is caused by the first communication device transmitting to the second communication device via the MIMO communication channel.