Abstract: An equalizer to be applied to signals received via at least one multiple input, multiple output (MIMO) channel is computed using a matrix equalizer computational device. The computed equalizer is applied to a received signal to recover an equalized representation of encoded data sent in a transmission. Errors are removed from the equalized representation of the encoded data to generate an error-corrected estimation of the encoded data sent in the transmission, and the equalized representation of the encoded data is compared to the error-corrected estimation of the encoded data. An updated equalizer is then computed to be applied to a subsequent signal based on the comparison.

Abstract: A method is provided for controlling access to a wireless communications medium. The method includes: sampling RF activity on the medium; autocorrelating samples to produce a first value indicative of autocorrelation computed with a first delay substantially matching periodicity of a signal of interest and to produce a second value indicative of autocorrelation computed with a second delay different from the first delay; monitoring the first value to determine whether the first value is possibly indicative of the signal of interest; monitoring the second value to determine whether the second value is indicative of an interferer signal; and preventing transmission of an RF transmit signal on the medium in response to the first value indicating that activity on the medium includes the signal of interest when the second value indicates that activity on the medium does not include an interferer signal.

Abstract: A system includes a signal processing module and a control module. The signal processing module receives a first clear channel assessment (CCA) signal for a first sub-channel of a communication channel, increases a pulse width of the first CCA signal by a predetermined period of time, and generates a second CCA signal. The control module receives the second CCA signal and a third CCA signal for a second sub-channel of the communication channel. The control module transmits data via one of the second sub-channel and the communication channel based on the second and third CCA signals.

Abstract: Methods and apparatus are provided for performing LLR value computations in a pipeline. Portions of a metric used to compute LLR values are computed in one pipeline part. The portions correspond to all permutations of some received signal streams. The portions are combined with one permutation x2 of the received signal stream that was not included in the previous pipeline computation in a subsequent pipeline part to produce M values associated with a particular bit position. At each subsequent clock cycle, a different permutation of x2 is combined with the previously computed portions producing different M values. State values corresponding to different values of bit positions of the received stream are computed by finding the minimum among the M values, in each clock cycle, that affect a particular bit position. The state values are combined to compute the LLR values for the bit position in a final pipeline part.

Abstract: A system and method of selecting a data detector alternately implement different data detection techniques such as maximum likelihood, zero forcing, and minimum mean square error. Selection of a particular technique may depend upon various factors. In some implementations, a decision whether to employ a specific strategy may be based upon a modulation and coding scheme utilized by the multiple-input, multiple-output (MIMO) system.

Abstract: A sub-matrix is selected from an estimated multiple input, multiple output (MIMO) channel matrix, wherein the estimated MIMO channel matrix is constructed based on a codebook. A singular value decomposition (SVD) is calculated based on the sub-matrix. A steering matrix is calculated based on the SVD and the codebook.

Abstract: A system includes a signal processing module and a control module. The signal processing module receives a first clear channel assessment (CCA) signal for a first sub-channel of a communication channel, increases a pulse width of the first CCA signal by a predetermined period of time, and generates a second CCA signal. The control module receives the second CCA signal and a third CCA signal for a second sub-channel of the communication channel. The control module transmits data via one of the second sub-channel and the communication channel based on the second and third CCA signals.

Abstract: A transmitter beamforming technique for use in a MIMO wireless communication system determines a partial description of a reverse channel without determining a full dimensional description of the reverse channel. A correction matrix is developed from the partial description of the reverse channel and a description of the forward channel. The correction matrix is used to process signals to be transmitted via the forward channel, and a steering matrix is used to perform beamforming in the forward channel.

Abstract: The disclosed technology relates to estimating the frequency response of a frequency division multiplexed (FDM) channel. In accordance with one aspect of the invention, a channel estimation circuit of a receiver can compute initial estimates of the frequency response of sub-channels in the FDM channel. A phase adjustment circuit can adjust the phase components of the initial estimates to provide phase-adjusted estimates. A smoothing circuit can apply a smoothing operation to the phase-adjusted estimates to provide smoothed phase-adjusted estimates. When necessary, a reverse phase adjustment circuit can reverse the phase adjustment by adjusting the phase components of the smoothed phase-adjusted estimates to provide final channel estimates.

Abstract: A first packet is transmitted via a forward channel corresponding to a signal direction from a first transceiver device to a second transceiver device, wherein the first packet includes a request to initiate calibration. A partial dimensional description of a reverse channel is determined based on the reception of a second packet received from the second transceiver device, wherein the second packet includes training information of spatial dimensions used for the transmission of the second packet but does not include training information for all available spatial dimensions of a reverse channel. A correction matrix is developed from the partial dimensional description of the reverse channel and a description of the forward channel, and the correction matrix and a steering matrix is used to process signals to be transmitted via the forward channel.

Abstract: A synchronization module for an orthogonal frequency-division multiplexing (OFDM) receiver system including a signal combination module that generates N combination signals that correspond to N received signals by performing at least one of weighted combining and selection and equal-gain-combining (EGC) on the N signals. A weighted signal generator module generates N weighted signals based on the N combination signals. N is an integer greater than one.

Abstract: The disclosed technology relates to a communication system and method in which multiple versions of a signal are processed to detect the signal. The communication system can include transmitters that communicate different versions of a signal to a receiver. The different versions are weighted versions of the signal and are communicated on different channels. The weight for a weighted signal is based on an inverse of an estimate of the phase shift of the particular channel to which the weighted signal will be communicated. The weights are also based on a unity gain such that each weighted signal has the same magnitude as the original signal. A receiver that receives the weighted signals processes the received signals to detect the original signal.

Abstract: A first packet is transmitted via a forward channel corresponding to a signal direction from a first transceiver device to a second transceiver device, wherein the first packet includes a request to initiate calibration. A partial dimensional description of a reverse channel is determined based on the reception of a second packet received from the second transceiver device, wherein the second packet includes training information of spatial dimensions used for the transmission of the second packet but does not include training information for all available spatial dimensions of a reverse channel. A correction matrix is developed from the partial dimensional description of the reverse channel and a description of the forward channel, and the correction matrix and a steering matrix is used to process signals to be transmitted via the forward channel.

Abstract: A spatial spreading unit is configured to utilize a spatial spreading matrix to distribute two or more encoded spatial data streams to transmission antennas. The spatial spreading matrix has components (i) associated with each row of a row dimension having a number of rows equal to the number of the transmission antennas to be used to transmit the encoded spatial data streams and (ii) associated with each column of a column dimension having a number of columns equal to the number of the encoded spatial data streams to be transmitted.

Abstract: A wireless communication system uses a spatial spreading matrix to simultaneously transmit various different streams of encoded symbol data simultaneously via multiple transmission antennas, wherein the spatial spreading matrix is designed to assure that the different transmission antennas provide equal power output in the presence of both correlated and uncorrelated data within the different encoded symbol streams. The use of this spatial spreading matrix reduces or eliminates the condition in which a particular one of the transmission antennas needs to operate at an output power that is significantly higher than the others of the transmission antennas, which might lead to saturation of, or to the non-linear or abnormal operation of a power amplifier associated with the particular transmission antenna, resulting in improper amplification for that particular transmission antenna.

Abstract: A transmitter beamforming technique for use in a MIMO wireless communication system determines a partial description of a reverse channel without determining a full dimensional description of the reverse channel. A correction matrix is developed from the partial description of the reverse channel and a description of the forward channel. The correction matrix is used to process signals to be transmitted via the forward channel, and a steering matrix is used to perform beamforming in the forward channel.

Abstract: Systems and techniques relating to processing a signal received over a wireless channel. A technique includes adaptively determining a data rate of packetized information transmission based on both a signal quality measure of a received signal and a channel quality measure derived from the received signal, the channel quality measure being indicative of frequency selectivity in the wireless channel. An apparatus includes a channel estimator configured to be responsive to a received OFDM signal corresponding to multiple frequency tones of the channel, and configured to evaluate channel response characteristics of the frequency tones; and a channel state indicator configured to generate a channel quality measure usable along with a signal quality measure in adaptively determining a data rate of packetized information transmission, wherein the channel quality measure is generated from the channel response characteristics of the frequency tones and is indicative of frequency selectivity in the wireless channel.

Abstract: A system configured to linearize a response of a nonlinear amplifier comprises a buffer to store a plurality of samples of an input signal to be amplified by the nonlinear amplifier. A self-receiver generates samples of an output signal of the nonlinear amplifier. A synchronization unit matches each sample of the output signal to a corresponding sample of the input signal stored in the buffer. A predistortion correction circuit generates a distortion correction function to be applied to the input signal to linearize the response of the nonlinear amplifier. The distortion correction function is generated based on a comparison of each matched sample of the output signal and corresponding sample of the input signal.

Abstract: An OFDM (Orthogonal Frequency Division Multiplexing) system may utilize pilot symbol structures including two or more pilot symbols with pilot information on alternate tones. The pilot information in one symbol is transmitted on mirror tones in another of the symbols. The pilot symbol structure may include a copy of one of the pilot symbols to aid in frequency offset estimation.

Abstract: A distortion correction circuit comprises memory that stores N samples of an input signal that occur at N different times, where N is an integer greater than two. A self-receiver samples an output signal that is generated by an RF power amplifier and that is based on said input signal. A synchronization unit selects one of said N samples by comparing said sampled output signal to said N samples. A predistortion unit generates a distortion correction function based on said selected one of said N samples and said output signal.