Abstract: Techniques are provided for computing downlink beamforming weights based on the received data at a base station from a mobile station in a MIMO communication system. An uplink transmission is received at a plurality of antennas at a first communication device from a second communication device, where the uplink transmission comprises a plurality of uplink subbands. The uplink spatial signature is estimated for each of the plurality of uplink subbands. The uplink spatial signature is decomposed into a plurality of direction of arrival (DOA) components for each uplink subband using a transform. Data representing multiple propagation paths between the first communication device and the second communication device is computed for each DOA component. A plurality of direction of departure (DOD) components for each of a plurality of downlink subbands is computed based on the data representing the multiple propagation paths.

Abstract: Techniques are provided to enable computation of beamforming weights for beamforming MIMO wireless communication between first and second wireless communication devices. At the first device comprising a first plurality of antennas, signals are received that are wirelessly transmitted from a different one of a second plurality of antennas of the second device during a corresponding one of a plurality of time slots. The first device computes beamforming weights from the received signals. When signals are to be transmitted from the first device to the second device, the first device applies the beamforming weights to signals to be transmitted from the first plurality of antennas of the first device to the second plurality of antennas of the second device.

Abstract: Techniques are provided herein to adaptively and independently disable use of subchannels in transmission sent from a first wireless communication device to a second wireless communication device. The first wireless communication device receives transmission sent to it by the second wireless communication device. The transmissions occupy some or all of a plurality of subchannels within a frequency band that are available for use in the transmission. The transmissions received at the first wireless communication device are evaluated in each subchannel for an over-the-air wireless link between the first wireless communication device and the second wireless communication device. Based on the evaluation, zero or more of the plurality of subchannels are independently disabled in transmissions that are sent by the first wireless communication device to the second wireless communication device.

Abstract: Techniques are provided herein to segment subcarriers for broadcast transmission to one or more mobile stations. A broadcast message to be transmitted from a first device is generated. The broadcast message comprises a plurality of symbols and each symbol is to be transmitted at a different one of a plurality of frequency subcarriers. The plurality of subcarriers is divided into groups and each group of subcarriers is assigned to a corresponding one of a plurality of antennas of the first device. The groups of subcarriers are transmitted from corresponding ones of the plurality of antennas.

Abstract: Techniques are provided herein to generate beamforming weight vectors for transmissions to be made from a first wireless communication device, e.g., a base station, to a second wireless communication device, e.g., a client device. The first device has a plurality of antennas and receives uplink transmissions from the second device, each uplink transmission comprising a group of frequency subcarriers. The first device computes channel information from the received uplink transmission and computes one or more trigonometric waveforms determined to approximate the channel information. One or more downlink beamforming weight vectors are computed at any given frequency subcarrier (thus in any frequency subband) by interpolation using the one or more trigonometric waveforms.

Abstract: Signal sequence detection techniques are provided to enable a wireless communication device to detect presence of a sequence, such as a preamble sequence, in the presence of other transmission that would otherwise interference with the ability of the device to detect the sequence. At the wireless communication device, energy in a frequency band is received and a receive signal is generated from the received energy. The receive signal is divided into windows of a predetermined time duration. A running auto-correlation of the receive signal is computed to produce an auto-correlation sequence for a sequence to be detected in the receive signal. Data representing a mask is generated for a window based on the receive signal. The mask is applied to the auto-correlation sequence to filter out portions of the auto-correlation sequence that are outside of the mask. A position of sequence, e.g.

Abstract: Techniques are provided to compute the physical carrier to interference-plus-noise ratio (PCINR) in a wireless communication system. In one embodiment, the PCINR is computed from received signals in active subcarriers in a preamble of a wireless transmission frame. In another embodiment, the PCINR is computed from a block of contiguous subcarriers in a symbol of received wireless transmission. The PCINR may be used to adjust a system parameter associated with wireless communication between wireless communication devices.

Abstract: At a wireless device operating in an unlicensed frequency band, energy received at a plurality of antennas is analyzed to detect interference on a channel in the unlicensed frequency band. The type of interference detected in the received energy is determined. Parameters are then generated for a nulling filter based on the type of interference detected in the received energy. The nulling filter is applied to the received energy at the plurality of antennas to produce a spatially filtered output. The spatially filtered output is evaluated to determine whether to send a transmission on the channel in the unlicensed frequency band.

Abstract: Link adaptive retransmission techniques are provided for use in connection with wireless communications between a first wireless communication device and a second wireless communication device. The first wireless communication device generates M packet error information values for the transmit session of a packet based on whether an acknowledgment message or a non-acknowledgment message is received from the second wireless communication device for a transmission and for previously sent transmissions even if less than M transmissions are sent by the first wireless communication device to the second wireless communication device upon completion of the transmit session. The first wireless communication device computes a retransmission fading margin based on the M packet error information values, from which an effective carrier-to-interference-plus-noise ratio is derived for selection of a modulation scheme.

Abstract: Techniques are provided to allow for implicit determination of the full spatial signature of a wireless channel between first and second wireless devices for multiple-input multiple-output (MIMO) wireless communication between the first and second wireless devices. The first wireless device receives uplink signals at a plurality of antennas of the first wireless device that are transmitted via a plurality of antennas of a second wireless device. Values at a plurality of subcarriers of the received signals across the plurality of antennas of the first wireless device are derived. Using a sliding window for groups of adjacent subcarriers, downlink beamforming weights are computed for each group of subcarriers using channel information of one or more proximate groups of subcarriers. The downlink beamforming weights for the respective groups of subcarriers are applied to a number of spatial streams in a downlink transmission to be transmitted to the second wireless device.

Abstract: Techniques are provided herein to compute beamforming weight vectors for pre-coding broadcast signals. First, system parameters for a device configured to wirelessly transmit one or more broadcast signals via a plurality of antennas are determined. Based on the system parameters a plurality of beamforming weight vectors are computed. The beamforming weight vectors are computed such that they have omni-directional like characteristics and such that correlation between beamforming weight vectors is relatively low. The plurality of beamforming weight vectors are applied to each of the one or more broadcast signals for transmission by the device to produce beamformed transmit signals for transmission via the plurality of antennas.

Abstract: Link adaptive retransmission techniques are provided for use in connection with wireless communications between a first wireless communication device and a second wireless communication device. The first wireless communication device generates M packet error information values for the transmit session of a packet based on whether an acknowledgment message or a non-acknowledgment message is received from the second wireless communication device for a transmission and for previously sent transmissions even if less than M transmissions are sent by the first wireless communication device to the second wireless communication device upon completion of the transmit session. The first wireless communication device computes a retransmission fading margin based on the M packet error information values, from which an effective carrier-to-interference-plus-noise ratio is derived for selection of a modulation scheme.

Abstract: A wireless base station apparatus is provided that is configured to automatically optimize the radiation pattern it uses when installed for operation in a wireless network in order to serve wireless client devices within a coverage area. The wireless base station is configured to determine its geographical location and to evaluate its geographical location based on stored geographical map data that indicates the physical geographical environment surrounding its geographical location. Based on the physical geographical environment surrounding the geographical location, the base station determines a radiation pattern best suited to serve wireless client devices within a coverage area.

Abstract: Techniques are provided to improve wireless beamformed communication between first and second wireless communication devices. At a plurality of antennas of the first wireless communication device (e.g., a base station) uplink transmissions sent from the second wireless communication device (e.g., a client or mobile device or station) are received. The first wireless communication device generates a downlink beamforming weight vector from received uplink transmissions, and computes a covariance matrix for received uplink transmissions. The first wireless communication device stores history information based on the covariance matrices for received uplink transmissions. The first wireless communication device computes first and second beamforming-space time code weight vectors based on the covariance matrix for an uplink transmission received in a current frame and the history information.

Abstract: Interference in an unlicensed frequency band is spatially filtered out from received signals at a wireless device operating in the unlicensed frequency band. Energy received at a plurality of antennas of the wireless is device is analyzed to detect interference in the unlicensed frequency band. The detected interference is classified by type. Parameters for a nulling filter are generated or selected based on the type of interference detected in the received energy. During a time interval when it is expected to receive desired signals, the nulling filter is applied using the parameters to signals obtained from energy received at the plurality of antennas during the time interval.

Abstract: A distributed antenna system and related methods are provided to reduce interference among wireless mobile devices in a distributed antenna system. A combiner is provided that is configured to be coupled to a plurality of remote transceiver stations deployed in a coverage area and which wirelessly transmit downlink signals to and receive uplink signals from wireless mobile devices. A plurality of input streams that carry uplink signals transmitted by wireless mobile devices are received on individually assigned signal paths from each of the remote transceiver stations. At least one parameter of an input stream received from the one or more of the remote transceiver stations is monitored. A mapping function is determined based on the monitoring. The plurality of input streams are combined based on the mapping function to produce the two or more output streams and the two or more output streams are sent to corresponding receivers in a base station.

Abstract: Techniques are provided for improving performance of a multiple-input multiple-output (MIMO) wireless communication system. At a first wireless communication device (e.g., a base station) having a plurality of antennas, uplink transmissions are received from a second wireless communication device (e.g., a client device). The base station determines a measure of multipath conditions between it and the second wireless communication device based on the received uplink transmissions. The base station applies downlink beamforming weight vectors together with power balance and phase adjustment factors depending on the measure of multipath conditions to transmit multiple downlink data streams across the plurality of antennas simultaneously to the second wireless communication device.

Abstract: A system and method are provided for improving the performance of a beamforming antenna array in a wireless communications system. By observing a predetermined times of channel spatial signatures, one or more test spatial signatures are generated based on statistical analysis of the observed spatial signatures for predicting channel characteristics. A beamforming weight is derived based on the generated test spatial signatures for beamforming by an antenna subsystem of the wireless communication system.

Abstract: Techniques are provided to improve receive beamforming at a wireless communication device that receives energy in a frequency band at M plurality of antennas, where the received energy includes desired signals and interference signals. The wireless communication device has no knowledge of the spatial signatures of the desired signals and interference signals. A weighted sum signal vector is computed from the received signals and a covariance matrix is computed from the receive signals. Eigenvalue decomposition of the covariance matrix is computed to obtain M eigenvalues of corresponding M eigenvectors of the covariance matrix. A correlation rate is computed between the M eigenvectors and the weighted sum signal vector. A combined receive beamforming and nulling weight vector is computed from the M eigenvectors and the weighted sum signal vector and based further on the correlation rate.

Abstract: A dynamically adaptive channel estimation process is provided for use in a wireless communication device. At a first device, a wireless transmission is received from a second device. The transmission comprises a plurality of successive symbols each of which comprises a plurality of subcarriers. The first device is configured to compute channel characterizing information for a wireless channel between the first device and the second device based on the received values at subcarriers of the successive symbols. The first device is configured to select one of a plurality of channel estimation schemes based on the channel characterizing information, and to compute an estimate of channel information for the wireless channel using the selected one of the plurality of channel estimation schemes.