The embodiments herein use a factorization based technique for determining filter coefficients for a subset of the subcarriers in a wireless frequency band. Once the filter coefficients for the subset of the subcarriers are calculated, the network device uses these filter coefficients to identify the filter coefficients in a neighboring subcarrier. To do so, the network device uses pseudo-inverse iteration to convert the already calculated filter coefficients into filter coefficients for a neighboring subcarrier. The network device can repeat this process for the next set of neighboring subcarriers until all the filter coefficients have been calculated.

An apparatus includes a first communication device with multiple antennas, operably coupled to a processor and configured to access a codebook of transformation matrices. The processor generates a set of symbols based on an incoming data, and applies a permutation to each of the symbols to produce a set of permuted symbols. The processor transforms each of the permuted symbols based on at least one primitive transformation matrix, to produce a set of transformed symbols. The processor applies, to each of the transformed symbols, a precode matrix selected from the codebook of transformation matrices to produce a set of precoded symbols. The codebook of transformation matrices is accessible to a second communication device. The processor sends a signal to cause transmission, to the second communication device, of multiple signals, each representing a precoded symbol from the set of precoded symbols, each of the signals transmitted using a unique antenna from the plurality of antennas.

An apparatus includes a first communication device with multiple antennas, operably coupled to a processor and configured to access a codebook of transformation matrices. The processor generates a set of symbols based on an incoming data, and applies a permutation to each of the symbols to produce a set of permuted symbols. The processor transforms each of the permuted symbols based on at least one primitive transformation matrix, to produce a set of transformed symbols. The processor applies, to each of the transformed symbols, a precode matrix selected from the codebook of transformation matrices to produce a set of precoded symbols. The codebook of transformation matrices is accessible to a second communication device. The processor sends a signal to cause transmission, to the second communication device, of multiple signals, each representing a precoded symbol from the set of precoded symbols, each of the signals transmitted using a unique antenna from the plurality of antennas.

Embodiments of this application disclose a channel estimation method and apparatus, and relate to the field of communications technologies, to help reduce indication overheads. The method may include: generating and sending indication information, where the indication information is used to indicate M N-dimensional precoding vectors, each precoding vector is applied to one of M frequency bands, the M N-dimensional precoding vectors form a space-frequency matrix, and the space-frequency matrix is generated by performing weighted combination on a plurality of space-frequency component matrices, where the space-frequency matrix is an MN-dimensional space-frequency vector or an XY space-frequency matrix, X and Y are one and the other of M and N, M1, N2, and both M and N are integers.

A millimeter wave channel estimation method comprises sending signals through a millimeter wave channel according to a first beamforming matrix, performing a channel estimation on the millimeter wave to generate a first measured matrix, and estimating and obtaining at least one angle of departure of the millimeter wave channel according to the first measured matrix and an angle compressive sensing matrix. The first beamforming matrix comprises a plurality of first beamforming vectors, and the first beamforming vectors respectively corresponds to a plurality of first beamforming patterns. The first measured matrix comprises a plurality of first measured parameters respectively corresponding to the first beamforming vectors.

A millimeter wave channel estimation method comprises sending signals through a millimeter wave channel according to a first beamforming matrix, performing a channel estimation on the millimeter wave to generate a first measured matrix, and estimating and obtaining at least one angle of departure of the millimeter wave channel according to the first measured matrix and an angle compressive sensing matrix. The first beamforming matrix comprises a plurality of first beamforming vectors, and the first beamforming vectors respectively corresponds to a plurality of first beamforming patterns. The first measured matrix comprises a plurality of first measured parameters respectively corresponding to the first beamforming vectors.

This disclosure describes a receiver having equalization with noise de-whitening mitigation for wireless communication. An input port receives, via an antenna, a signal communicated over a wireless communication link, the signal comprising a noise component. Control circuitry performs zero forcing equalization of the received signal to generate a zero forcing equalization result signal. The zero forcing equalization causes de-whitening of the noise component by increasing a correlation among elements of the noise component. The control circuitry mitigates the de-whitening of the noise component by: determining a noise variance value based on channel properties of the wireless communication link, and modifying the zero forcing equalization result signal based on the noise variance value. The modified zero forcing equalization result signal is communicated, via an output port, to log-likelihood ratio (LLR) generation circuitry for LLR computation.

Methods and apparatus for sub-block based architecture of Cholesky decomposition and channel whitening. In an exemplary embodiment, an apparatus is provided that parallel processes sub-block matrices (R.sub.00, R.sub.10, and R.sub.11) of a covariance matrix (R) to determine a whitening coefficient matrix (W). The apparatus includes a first LDL coefficient calculator that calculates a first whitening matrix W.sub.00, lower triangle matrix L.sub.00, and diagonal matrix D.sub.00 from the sub-block matrix R.sub.00, a first matrix calculator that calculates a lower triangle matrix L.sub.10 from the sub-block matrix R.sub.10 and the matrices L.sub.00 and D.sub.00, and a second matrix calculator that calculates a matrix X from the matrices D.sub.00 and L.sub.10. The apparatus also includes a matrix subtractor that calculates a matrix Z from the matrix X and the sub-block matrix R.sub.11, a second LDL coefficient calculator that calculates a third whitening matrix W.sub.11, lower triangle matrix L.sub.11, and a diagonal matrix D.sub.11 from the matrix Z, and a third matrix calculator that calculates a second whitening matrix W.sub.10 from the matrices L.sub.00, L.sub.10, L.sub.11, and D.sub.11.

Provided are a QR decomposition-based detection method and apparatus based on overlapped multiplexing. The QR decomposition-based detection method includes: step S1: obtaining a receive sequence, where the receive sequence is a sequence obtained by encoding and modulating an input signal based on a multiplexing waveform matrix and transmitting the signal through a Gaussian channel; and step S2: detecting the receive sequence by using a QR decomposition algorithm, where step S2 includes: decomposing a foreknown multiplexing waveform matrix into a unitary matrix and an upper triangular matrix; performing matrix multiplication processing on the receive sequence based on the unitary matrix, to obtain a data sequence; and performing layer-by-layer detection on the data sequence based on the data sequence, the upper triangular matrix, and a quantized decision factor.

There are disclosed techniques (e.g., apparatus, methods) for estimating an impulse response of a linear system. An apparatus is configured to generate a transmit signal on the basis of a first sequence. The apparatus is configured to obtain a receive signal and to multiply the receive signal with a second sequence, to obtain a modified receive signal, wherein the second sequence is different from the first sequence. The apparatus is configured to analog-to-digital, ADC, convert an integration result in order to obtain a sample value, the integration result being based on an integration of the modified receive signal over a period of time. The apparatus is configured to obtain an estimate of the impulse response on the basis of a plurality of sample values.