A communication device is configured to correlate a first signal with a second signal at a designated interval, the second signal corresponding to the first signal and being received by the communication device where the other communication device transmits a signal including a pulse as the first signal, convert a correlation computation result that is a result of correlating the first signal with the second signal at the designated interval into a format including a matrix product of an expanded modal matrix and an expanded signal vector, the expanded modal matrix including a plurality of elements indicating the correlation computation result obtained when assuming that the signals are received at respective set times, the expanded signal vector being a vector including a plurality of elements, each of which indicates whether or not there is a signal received at each of the set times and amplitude and phase of the signal.

Provided are a multipath separation method and device, and a storage medium. The multipath separation method includes: extracting frequency domain response characteristics of received reference signals in at least two different frequency bands; for each of the at least two different frequency bands, constructing a Toeplitz matrix; combining Toeplitz matrixes corresponding to the at least two different frequency bands; performing singular value decomposition on the synthesized Toeplitz matrix; determining a signal space matrix and a noise space matrix according to the decomposed matrix; constructing a plurality of frequency domain response vectors according to frequency domain response characteristics of local signals having different delays and are the same as the received reference signals; and comparing a first preset threshold with inner products between each of the plurality of frequency domain response vectors and the noise space matrix respectively, and determining a delay corresponding to each of a plurality of frequency domain response vectors in which inner products satisfy the first preset threshold to be a delay of one path in the multipath.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

A modified orthogonal frequency-division multiplexing (OFDM) communication system based on virtual decomposition of the channel is proposed. The system is fully compatible with standard OFDM transmitters and maintains several blocks of standard OFDM receivers. The proposed approach achieves also incoherent reception of multicarrier signals even with a simple autocovariance DPSK detector. This novel system substantially surpasses the performance of current approaches while requiring low computational complexity. Two preferred embodiments are described; one with coherent reception using pilot signals, and the second with incoherent receiver of differentially encoded signals.

Embodiments of this application disclose a channel estimation method and apparatus, and relate to the field of communications technologies. The method may include: generating and sending indication information, where the indication information is used to indicate L space-frequency basis vectors for constructing an M×N-dimensional space-frequency vector; the space-frequency vector includes M N-dimensional precoding vectors, each precoding vector is used in one of M frequency bands, and the space-frequency vector is generated by performing a weighted combination on L space-frequency component vectors; each of the L space-frequency component vectors is a vector including M×N elements that are in one of the L space-frequency basis vectors, and each of the L space-frequency basis vectors is an N.sub.f×N-dimensional vector; the space-frequency basis vector is a three-dimensional oversampled (DFT) vector; and L≥2, N.sub.f≥M≥1, N≥2, and L, M, N, and N.sub.f are all integers.

The disclosure provides a subspace-based blind identification algorithm of an ocean underwater acoustic channel for multi-channel fir filter, which adopts a technical solution that a channel impulse response coefficient is calculated by quadratic minimization. The disclosure has beneficial effects that estimation precision can be met when using a proper number of samples, and especially when a few noise vectors are used for estimating channel parameters, so that calculation amount is greatly reduced.

A MIMO-OFDM system for increasing reliability includes a transmission terminal that includes N.sub.t transmission antennas and transmits a MIMO signal through relay terminals, and a reception terminal that receives the MIMO signal from the relay terminal through N.sub.r reception antennas, and the transmission terminal extracts a composite channel coefficient from a composite channel generated by matching a channel between the transmission terminal and the reception terminal with a channel between each of a plurality of the relay terminals and the reception terminal, selects the relay terminal corresponding to the composite channel coefficient having a maximized channel capacity from among the plurality of relay terminals by using the extracted composite channel coefficient, and transmits a MIMO signal to the reception terminal through the selected relay terminal.

Methods, systems, and devices for wireless communication are described. A wireless device may determine that a channel is reciprocal and perform an implicit sounding process. During the implicit sounding process, the wireless device may estimate the uplink channel by measuring a first uplink multi-user multiple input multiple output (MU-MIMO) transmission. The wireless devices may then update the uplink channel estimation based by measuring a second MU-MIMO transmission that is received after a downlink transmission from the wireless device. Based on the updated uplink channel estimation, the wireless device may send a beamformed MU-MIMO transmission to a number of other wireless devices.

Technology for a user equipment (UE) operable to assist a Next Generation NodeB (gNB) for beamforming is disclosed. The UE can determine a covariance matrix for a channel between the UE and the gNB. The UE can quantize the covariance matrix to obtain a quantized covariance matrix. The quantized covariance matrix can include M best diagonal entries that are selected from the covariance matrix, wherein M is an integer. The UE can encode the quantized covariance matrix as feedback for transmission to the gNB.