A method of compensating for IQ mismatch (IQMM) in a transceiver may include sending first and second signals from a transmit path through a loopback path, using a phase shifter to introduce a phase shift in at least one of the first and second signals, to obtain first and second signals received by a receive path, using the first and second signals received by the receive path to obtain joint estimates of transmit and receive IQMM, at least in part, by estimating the phase shift, and compensating for IQMM using the estimates of IQMM. Using the first and second signals received by the receive path to obtain estimates of the IQMM may include processing the first and second signals received by the receive path as a function of one or more frequency-dependent IQMM parameters.

A signal detection method for a MIMO-OFDM wireless communication system includes obtaining a channel matrix of each subcarrier through channel estimation for each MIMO-OFDM data packet in a plurality of MIMO-OFDM data packets; receiving a reception vector of each subcarrier; performing channel matrix preprocessing for the channel matrix of each subcarrier to generate a global dynamic K-value table, in which the global dynamic K-value table includes a global dynamic K-value corresponding to each search layer of each subcarrier; performing MIMO detection for each OFDM symbol in the MIMO-OFDM data packet, in which the MIMO detection includes performing the following steps for each subcarrier of a current OFDM symbol: reading channel matrix preprocessing results and reception vector of the current subcarrier; transforming the reception vector of the current subcarrier into an LR search domain; and performing K-best search for the current subcarrier to obtain an LR domain candidate transmission vector of the current subcarrier, in which a K-value applied to each search layer of the current subcarrier during the K-best search is a global dynamic K-value in the global dynamic K-value table corresponding to the search layer.

The application provides a short training sequence design method and apparatus. The method includes: determining a short training sequence, where the short training sequence may be obtained based on an existing sequence, and the short training sequence with comparatively good performance may be obtained through simulation calculation, for example, by adjusting a parameter; and sending a short training field on a target channel, where the short training field is obtained by performing inverse fast Fourier transformation IFFT on the short training sequence, and a bandwidth of the target channel is greater than 160 MHz.

Various embodiments of the present disclosure relate to transmitter systems, methods, and instructions for signal predistortion. The transmitter system includes an intermodulation distortion (IMD) filter module configured to filter a detected feedback signal (Y.sub.in) to generate a targeted filtered signal (Y.sub.out), a digital pre-distortion (DPD) coefficient estimation module configured to update signal generation coefficients based on comparing an input signal (S.sub.in) with the targeted filtered signal (Y.sub.out), and a distortion compensation processing module configured to generate a pre-distorted signal (U.sub.out) based on the input signal (S.sub.in) using the updated signal generation coefficients.

The application provides a short training sequence design method and apparatus. The method includes: determining a short training sequence, where the short training sequence may be obtained based on an existing sequence, and the short training sequence with comparatively good performance may be obtained through simulation calculation, for example, by adjusting a parameter, and sending a short training field on a target channel, where the short training field is obtained by performing inverse fast Fourier transformation IFFT on the short training sequence, and a bandwidth of the target channel is greater than 160 MHz.

Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter applies a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.

Systems and methods for enabling pre-compensation of timing offsets in OFDM receivers without invalidating channel estimates are described. Timing offset estimations may be sent along with the received OFDM symbols for FFT computation and generating a de-rotated signal output. The timing offset estimation may provide a reference point for dynamic tracking of timing for an OFDM signal and estimated based on an integral value associated with the OFDM signal.

The data recovery from gradients (DRG) of sub-carriers of a received OFDM signal affected by deterministic and random distortions introduced by a transmission link, contributes a method and a system for utilizing gradients characterizing shapes of OFDM sub-carriers comprised in such OFDM signal for recovering data symbols transmitted originally.

Disclosed by the present invention is a sub-band selection activation-based multi-band hyperbolic frequency modulation spread spectrum underwater acoustic communication method. The present invention discloses: dividing the available bandwidth of an underwater acoustic system into a plurality of sub-bands, performing hyperbolic frequency modulation on each of the sub-bands respectively, and performing spread spectrum modulation on the plurality of sub-bands within the same frequency modulation period, thus implementing multi-band parallel transmission. Hence, within each frequency modulation period, the divided plurality of sub-bands is grouped, and each sub-band group activates different sub-bands for transmission according to different options for transmitting data. Compared to other underwater acoustic hyperbolic frequency modulation communication solutions, the present invention further improves the frequency band utilization of the system, and the energy efficiency is also improved.

An apparatus for correcting a deviation between a plurality of transmission channels includes a first transmission channel and a second transmission channel. The apparatus also includes a phase offset unit configured to set a phase offset between the first transmission channel and the second transmission channel such that a phase deviation between the first transmission channel and the second transmission channel deviates from zero, a power detection unit configured to detect signal powers of the first transmission channel and the second transmission channel under the phase offset, a processing unit configured to determine, based on the detected signal powers, a deviation correction value between the first transmission channel and the second transmission channel, where the deviation correction value includes a phase correction value, and a phase correction unit configured to set the phase correction value between the first transmission channel and the second transmission channel.