237 results about "Carrier frequency offset" patented technology

The invention discloses a joint estimation method for timing advance and frequency offset based on a conjugate symmetric ZC sequence, which relates to the technical field of wireless communication and comprises the following steps of: inputting a leader sequence extracted from a demodulated received signal; two ZC sequences in the leader sequence are respectively in cross-correlation with a local ZC sequence, and a peak value of a cross-correlation result amplitude is obtained; iteratively performing fractional frequency offset compensation estimation to obtain a fractional frequency offset estimation value and a compensated leader sequence; performing timing advance estimation and integer frequency offset estimation to obtain a timing advance estimator and an integer frequency offset estimator; obtaining a frequency offset estimation value by combining the decimal multiple and integer multiple frequency offset estimation values; and ending the timing advance and frequency offset estimation, and outputting estimated values of the timing advance and the frequency offset. According to the method, the negative influence of the decimal frequency offset on the ZC sequence is eliminated in a mode of iteratively compensating and estimating the decimal frequency offset, and high-performance timing advance and frequency offset joint estimation with robustness to frequency shift and noise is realized based on the structure of the conjugate symmetric ZC sequence; the method is suitable for a non-ground network communication scene with large Doppler frequency shift and low receiving signal-to-noise ratio.

The invention relates to the technical field of signal processing, in particular to an intelligent blind equalization method and device for large-scale carrier frequency deviation, and the method comprises the steps: carrying out the down-conversion of an original received signal of a preset modulation type, so as to sample an original complex sampling point sequence with large-scale carrier frequency deviation; performing local information exchange, parameter correction and splicing on the original complex sampling point sequence to obtain a compensated complex sampling point sequence; performing pre-extraction and channel amplification on the compensated complex sampling point sequence to obtain pre-extraction features containing implicit channel state information, and further extracting spatial information and time sequence dependence in the pre-extraction features to balance multipath fading of the original complex sampling point sequence and obtain balanced output; and demodulating the original bit information of the original complex sampling point sequence according to the balanced output. Therefore, the problem that a blind equalization method in the related technology cannot effectively adapt to a time-varying multipath channel and a scene with large-scale carrier frequency deviation is solved.

The invention discloses an adaptive equalization method for combined compensation of carrier frequency offset and channel linear damage. The adaptive equalization method specifically comprises the following steps: taking data subjected to matched filtering, clock synchronization, orthogonality and normalization as input signals; for an input signal, using the filter linear damage compensation weight vector and the frequency offset compensation weight coefficient to obtain output data of the filter; obtaining an expected value of filter output data, and calculating to obtain a theoretical error value of adaptive equalization; and obtaining a filter weight vector used for next adaptive equalization according to the theoretical error value. The adaptive equalization method for combined compensation of carrier frequency offset and channel linear impairment is suitable for a coherent optical transmission system, uses an adaptive equalizer to compensate signal frequency offset and channel linear impairment at the same time, does not need an additional frequency offset estimation algorithm, meets the advantages of multiple rates and multiple modulation formats, and is high in convergence speed and high in robustness. And the calculation complexity is low.

The invention discloses a data reading method and system based on an RFID reader-writer, particularly relates to the technical field of radio frequency identification data acquisition, and is used for solving the problem that the communication reliability of an existing RFID system is reduced due to carrier frequency deviation and multipath interference in a high-speed mobile environment. A phase change characteristic and an error rate index are obtained through double-antenna receiving signal analysis, when the error rate exceeds a limit, spatial correlation and error rate distribution difference are jointly analyzed to determine a multipath interference level, and meanwhile, a relative motion state is detected and judged through a phase track curvature characteristic. And dynamically selecting an optimal modulation coding mode to read data again according to the calculated motion speed estimated value and the interference level, thereby realizing the optimal balance between the communication rate and the reliability in the mobile environment.

A method of a wireless communication device, includes compensating for a first phase of a first training symbol and a second phase of a second training symbol following the first training symbol, based on a reference carrier frequency offset (CFO) corresponding to one of a plurality of subcarriers of a received frame in a time domain; calculating residual CFOs respectively for the plurality of subcarriers of the received frame, based on the reference CFO; compensating for phase differences between the first training symbol and the second training symbol for each of the plurality of subcarriers, based on the residual CFOs in a frequency domain; and estimating at least one of noise power and signal-to-noise ratio (SNR) of the received frame, based on the first training symbol and the second training symbol after compensating for the phase differences between the first training symbol and the second training symbol.

The invention discloses an underwater acoustic OFDM impulse noise estimation enhancement method based on distributed compressed sensing, and relates to the technical field of underwater acoustic communication. Carrying out frequency offset correction on the received OFDM signal by adopting a plurality of carrier frequency offset compensation values to obtain a plurality of groups of related signals; constructing an orthogonal projection matrix, projecting a received signal to a specific orthogonal subspace to eliminate channel components, and separating impulse noise; constructing a joint observation matrix by using the time domain sparsity of the impulse noise and the strong correlation under different carrier frequency offset compensation; and carrying out joint sparse reconstruction on the multiple groups of observation signals by adopting a distributed compressed sensing algorithm, and estimating an impulse noise time domain signal. A distributed compressed sensing algorithm is adopted, two characteristics of impulse noise are utilized, impulse noise estimation accuracy is improved, an impulse noise estimation effect is enhanced, and the problem that impulse noise estimation accuracy is limited under the condition of limited pilot frequency quantity is solved.

The invention discloses a logical channel LoRa data packet detection method based on window sliding, a medium and equipment, and belongs to the technical field of network communication. The method comprises the following steps: for a received data packet, extracting peak values from the same symbol by tracking a change mode of a plurality of peak values in a continuous time window, and generating a corresponding peak value sequence by matching the peak values of the symbols to obtain a plurality of peak value sequences; identifying the characteristics of the same data packet in the frequency domain and the time domain, and matching the plurality of peak sequences to obtain a matched peak sequence; extracting LoRa parameters of the data packet by combining the characteristics of the plurality of peak sequences by using the matched peak sequences, the LoRa parameters including a spreading factor and a bandwidth; and aligning the demodulation windows in the frequency domain and the time domain, and evaluating the carrier frequency offset of each data packet. According to the invention, the data packet can be detected more accurately, and high-quality and high-capacity communication is realized.

The present invention discloses a blind estimation method, system and medium for the carrier frequency offset of FSK based on the L&R algorithm. The method includes the following steps: conjugately multiplying each local modulation sequence with the baseband signal of the FSK signal respectively to obtain corresponding first signals, the number of local modulation sequences corresponding to the modulation order of the FSK signal, and the local modulation sequences being different from each other; low-pass filtering and accumulating all the first signals to obtain a second signal with the modulation information eliminated; discretizing the second signal and then calculating the accumulated sum of the second signal, and substituting the accumulated sum of the second signal into the L&R algorithm to obtain the frequency offset estimation value of the FSK signal. The present invention can perform frequency offset estimation without prior information and has strong practicability.

The invention provides a communication radiation source individual identification method based on time domain and time sequence coding constellation diagram feature fusion. The method is used for realizing stable identification of different transmitters under non-ideal conditions of carrier frequency offset, noise interference and the like. The method comprises the following steps: firstly, carrying out normalization and fixed-length interception on a received I / Q signal, and calculating an oversampling multiple according to a symbol rate and a time resolution; then, a time domain and time sequence coding constellation diagram double-branch feature extraction network is constructed, a time domain structure feature is extracted from a time domain branch by adopting a one-dimensional modified ResNet18, and a constellation diagram with time information is generated from a time sequence coding constellation diagram branch through a time sequence coding constellation module and the feature that the phase changes along with time is extracted; and carrying out joint modeling on the two types of features through a trainable weighted fusion mechanism. In the training stage, the performance of the model is improved by adopting cross entropy loss, an Adam optimizer, learning rate scheduling and an early stop strategy. In the reasoning process, input signals are classified by using the model weight with the highest verification accuracy, and a communication radiation source individual identification result is output. Experimental results show that the method can effectively enhance the frequency offset robustness and generalization ability of the model, realizes high-precision identification of the individual communication radiation source, and is suitable for the fields of security access of the Internet of Things, spectrum monitoring, electronic countermeasures and the like.

The invention discloses a radio frequency fingerprint hiding method based on feature compensation. The method comprises the following steps: at a transmitter end, carrying out carrier frequency offset compensation, I / Q imbalance compensation and PA nonlinear distortion compensation on a to-be-transmitted signal in sequence by using a preset joint compensation model to obtain a transmitted signal after radio frequency fingerprint hiding; the joint compensation model is constructed by the following steps: carrying out carrier frequency offset estimation and compensation, I / Q imbalance estimation and compensation and PA nonlinear distortion estimation on a received signal of a receiver in sequence, and constructing the joint compensation model according to a carrier frequency offset estimation result, an I / Q imbalance estimation result and a PA nonlinear distortion estimation result. According to the method, a scientific and reasonable parameter estimation and compensation sequence is designed, an illegal receiver is effectively prevented from extracting radio frequency fingerprints from received signals, the classification precision of the RFFI technology can be effectively reduced, and the privacy protection and recognition resistance of a transmitter are remarkably enhanced.

The invention belongs to the field of unmanned aerial vehicle auxiliary MIMO system physical layer authentication, and discloses a bidirectional privacy protection unmanned aerial vehicle auxiliary MIMO system physical layer authentication method, which comprises the following steps: step 1, considering a frame consisting of a pilot frequency and a data symbol, and establishing a carrier frequency offset statistical model representing the identity of an unmanned aerial vehicle; step 2, establishing a CFO session key negotiation algorithm based on the carrier frequency offset statistical model and the elliptic curve cryptography; 3, designing an unmanned aerial vehicle identity bidirectional authentication framework to complete identity authentication based on a carrier frequency offset statistical model and a CFO session key negotiation algorithm; and 4, based on the carrier-free frequency offset statistical model, performing authentication performance analysis, and quantifying the authentication effect. Compared with the prior art, the method has the advantages that the robustness and the accuracy of attacking identity-based impersonation attacks are better.

The application provides an uplink sensing integrated system signal processing method and device and a storage medium, comprising: performing coarse synchronization on a first signal received by a plurality of antennas to obtain a first time offset, a first carrier frequency offset and a second signal after coarse synchronization; performing preliminary channel estimation according to the second signal to obtain an estimated first channel state information tensor; performing deep learning based on a hybrid neural network according to the first channel state information tensor to obtain an estimated second channel state information tensor, a second time offset and a second carrier frequency offset; performing tensor decomposition according to the second channel state information tensor, and acquiring sensing information according to the first time offset, the first carrier frequency offset, the second time offset and / or the second carrier frequency offset. The application realizes more accurate synchronization error estimation and channel state information denoising, guarantees more reliable communication performance, and realizes high-precision positioning and speed measurement of sensing.

This disclosure provides methods, components, devices and systems for carrier frequency offset compensation between access points for coordinated beamforming sounding and transmission. During a channel sounding phase of a CBF operation, a first AP acting as a frequency reference may transmit a frequency reference frame. A second AP may use the frequency reference frame to estimate a CFO and pre-compensate for the CFO for subsequent transmissions during the channel sounding phase and during a transmission phase of the CBF operation. In some examples, the first AP may own a shared TXOP of the transmission phase. The second AP may receive a frequency reference frame for estimating the CFO. In some other examples, the second AP may own the shared TXOP. The second AP may request the first AP to transmit the frequency reference frame. Alternatively, the second AP may use a CFO value estimated during the channel sounding phase.

The application relates to a time-frequency synchronization method for a high-speed moving platform, which comprises the following steps: at a transmitting end, a preamble sequence is obtained by performing mathematical transformation on a constant envelope zero autocorrelation sequence through a weight factor, conjugate processing and symmetric transformation; at a receiving end, the received signal is processed step by step, (1) the continuously received signal is subjected to mathematical operation with a local weight factor sequence to obtain a timing metric sequence, the maximum value is selected and the corresponding position is recorded to complete symbol timing synchronization; (2) a received pilot sequence is extracted, fractional carrier frequency offset estimation and compensation are carried out, and integer carrier frequency offset estimation and compensation are carried out; (3) the received pilot sequence is extracted, and common phase offset estimation and compensation are carried out by using a local preamble sequence. The application realizes high-accuracy timing acquisition and high-precision frequency offset correction capability under the condition of low signal-to-noise ratio, high dynamic Doppler frequency shift and non-matching of transmitting and receiving end crystal oscillators.

The present invention provides a method, apparatus, and medium for frequency offset estimation in a space-ground integrated network. The method includes: obtaining synchronization information blocks for downlink synchronization in OFDM systems of different sub-networks in the space-ground integrated network; for multiple sub-networks in the space-ground integrated network, respectively obtaining parameter information of each sub-network from the synchronization information blocks; according to the obtained parameter information, establishing a system of equations for linearly estimating the carrier frequency offset; and solving the system of equations by the least squares method to obtain estimation results of each component of the carrier frequency offset. The frequency offset estimation method, apparatus, and medium provided by the present invention can solve the problem of estimating each component of the frequency offset under the conditions of low signal-to-noise ratio, large propagation delay, high Doppler frequency shift, and rapid change of Doppler frequency shift faced by the space-ground integrated network architecture.

This disclosure provides methods, components, devices and systems for interference mitigation (IM) mode signaling designs for a physical layer protocol data unit (PPDU). Some aspects relate to IM mode signaling designs according to which a wireless communication device determines a tone plan in accordance with an ON or OFF state of the IM mode. For example, an ON state of the IM mode may correspond to a first tone plan and an OFF state of the IM mode may correspond to a second tone plan. The first tone plan may define first fixed pilot tone locations, with pilot tones at the first fixed pilot tone locations being usable as IM pilot tones and / or usable as carrier frequency offset (CFO) pilot tones. The second tone plan may define second fixed pilot tone locations, with pilot tones at the second fixed pilot tone locations being exclusively usable as CFO pilot tones.

Aspects discussed herein include a method and associated network device and computer program product. The method includes receiving a network packet and estimating a power profile corresponding to a plurality of subcarriers of a channel using a preamble of the network packet. The method also includes estimating a carrier frequency offset using the power profile and estimating a clock offset using the carrier frequency offset.

The invention provides a time-frequency synchronization method and device and a medium, and relates to the technical field of communication. The method comprises the following steps: a receiving end receives a signal transmitted by a satellite; estimating and compensating the carrier frequency offset (CFO) of the signal so as to compensate the Doppler frequency shift of the central subcarrier of the signal; and estimating and compensating the sampling frequency offset (SFO) of the signal so as to compensate the residual Doppler frequency shift components of other subcarriers of the signal after the Doppler frequency shift of the central subcarrier is compensated. Aiming at the problem that a communication system fused with satellites can generate large Doppler frequency shift, the carrier frequency offset (CFO) and the sampling frequency offset (SFO) are estimated and compensated, so that the influence of the Doppler frequency shift on communication is better reduced.

The present disclosure relates to a device and a communication method for appropriately determining: the timing and the frequency of an R2D signal used for CFO calibration; and the detection of the R2D signal used for the CFO calibration. The device, which has lower complexity than a Narrow Band Internet of Things (NB-IoT) device, comprises: a reception unit that receives a reception signal including control information from a wireless communication device; and a control unit that determines which sequence / pattern / length is to be detected from a signal of a clock acquisition part of the reception signal on the basis of the control information in the reception signal. The control unit determines to use a signal of the sequence / pattern / length detected from the clock acquisition part for timing calibration and calibration of a carrier frequency offset.

The present invention provides a time-frequency synchronization method and apparatus applicable to DRM, belonging to the field of communication technologies. The method includes: determining the robust mode and the symbol coarse timing starting point of the received DRM signal; estimating and compensating the fractional frequency offset at the symbol coarse timing starting point; determining the transmission frame coarse starting point according to the time pilot signal; estimating and compensating the integer frequency offset at the transmission frame coarse starting point by using the time pilot; estimating the precise transmission frame starting point by using the gain pilot; and estimating and compensating the precise fractional frequency offset at the precise transmission frame starting point by using the gain pilot. The present invention is applicable to various robust modes and spectrum occupancy situations of DRM. Its synchronization performance is not affected by the initial frequency offset. By continuously tracking the symbol timing offset and carrier frequency offset to reduce ISI and ICI, it has the advantages of high precision, good robustness, simple process, and being suitable for transplantation to a hardware system.

The invention discloses a carrier frequency offset and I / Q joint compensation method and system for a Bluetooth receiver, and the method comprises the steps: obtaining an initial receiving signal of the Bluetooth receiver, and carrying out the time domain preprocessing and fast Fourier transform, thereby obtaining a frequency spectrum; calculating normalized frequency offset based on the spectral line with the maximum amplitude in the frequency spectrum; according to the normalized frequency offset, adaptively selecting a target interpolation algorithm to obtain a fine carrier frequency offset estimation value; carrying out smoothing processing, and carrying out frequency offset compensation on the initial receiving signal by using a smoothed frequency offset estimation value to obtain a baseband I / Q signal; performing low-pass filtering, down-sampling and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; and estimating a gain imbalance parameter and a phase imbalance parameter based on the zero-mean baseband signal, performing blind compensation, and outputting a compensated orthogonal I / Q signal. According to the method, the carrier frequency offset is estimated with high precision through a dynamic selection interpolation algorithm, I / Q imbalance is compensated cooperatively, and the demodulation performance and robustness of the Bluetooth receiver are improved.

Provided in the embodiments of the present application are a communication method and a related device. In the method, a first device sends a first signal and a second signal, wherein the first signal is used for transmitting data, the second signal is used for being modulated by a second device to obtain a third signal, the third signal is a feedback signal of response data, and the second signal is also used for carrier frequency offset (CFO) calibration of a third device. On the basis of the solution, the second signal sent by the first device to the second device is not only used for signal modulation of the second device, but is also used for CFO calibration of the third device, that is, data transmission of the second device and the CFO calibration of the third device are realized by means of the second signal, so as to meet the communication requirements of both the second device and the third device, thereby improving the communication efficiency.

A low complexity clock drift estimation scheme for UWB-MMS ranging is presented that assumes that a sampling frequency offset (SFO) and a carrier frequency offset (CFO) are driven from the same clock source. The SFO is first estimated with a plurality of CIR segments, and the SFO is used to compensate for the CFO of the CIR segments. A fine CFO estimate is then obtained from the compensated CIR. Combining the coarse SFO and fine CFO estimates to resample and phase rotate the original CIR can significantly improve the performance of the CIR combination, thereby improving the performance of ranging.

This invention discloses a method and system for radio frequency fingerprinting of narrowband IoT transceivers. The method involves a receiver acquiring wireless messages sent by the transceiver to be identified, obtaining in-phase / orthogonal discrete sample sequences, locating and extracting preamble sample segments, performing a short-time Fourier transform on the preamble sample segments to generate a spectrogram energy matrix, and extracting compressed time-frequency features through singular value decomposition. The main component of the carrier frequency offset is obtained based on the cross-correlation peak position shift between rising and falling chirps, and the carrier frequency offset correction component is obtained based on the phase drift of adjacent rising chirps. The compressed time-frequency features and the carrier frequency offset estimation results are concatenated into a fused feature vector, which is then input into a convolutional neural network classification model to output the device category and category confidence. This invention reduces the dependence on channel location features and decreases model input overhead, making it suitable for online identification of narrowband IoT devices.

The present invention provides a synchronization circuit device and a method for generating a synchronization signal. The synchronization circuit device includes: a carrier frequency offset blind estimation circuit, which is configured to receive a multi-bit frequency domain data stream and a synchronization signal fed back from an address synchronization circuit, and output a first carrier frequency offset estimation value; a carrier frequency offset compensation circuit, which is configured to perform carrier frequency offset compensation on the received multi-bit frequency domain data stream according to the first carrier frequency offset estimation value, and output a frequency domain data stream without carrier frequency offset as a single bit; and an address synchronization circuit, which is configured to receive the frequency domain data stream without carrier frequency offset as a single bit, and output a synchronization signal.

The invention belongs to the technical field of wireless communication, discloses a high-precision frequency synchronization method for an OTFS system, and provides a coarse and fine carrier frequency offset hierarchical estimation scheme for solving frequency offset by mainly using a differential phase between adjacent symbols and solving the problem of poor frequency offset estimation precision in the existing frequency synchronization algorithm. Coarse frequency offset estimation compensates carrier frequency offset to a working range of fine frequency offset estimation while ensuring a frequency offset estimation range, then the fine frequency offset estimation is utilized to further improve estimation precision, and the frequency offset estimation method provided by the invention achieves estimation precision close to a theoretical limit with low implementation complexity, and has a wide application prospect. Compared with a traditional single-stage frequency offset estimation method, the method has obvious advantages.

Methods, systems, and apparatus for wireless communication are described. A user equipment (UE) may receive a first indication of a set of reference signal instances within a resource set. The UE may receive a second indication of a resource element format for the reference signal instances in the reference signal instance set, the resource element format including one or more empty resource elements and one or more reference signal resource elements. The UE may further receive a reference signal from a base station for estimating a carrier frequency offset (CFO) based on the first indication of the set of reference signal instances and the second indication of the resource element format for the reference signal instances. The UE may then communicate with the base station based on the received reference signal.

This invention discloses a wireless continuous communication synchronization method and system based on time-frequency joint feedback correction. The method includes: a slave device calculating a carrier frequency offset estimate and a timing estimate L of the received signal using a preamble sequence; calculating a remaining carrier frequency offset estimate and a remaining timing offset estimate using an auxiliary pilot; and the slave device locating the starting point of the data stream based on the timing estimate L. The slave device then feeds back the carrier frequency offset estimate ΔF, the remaining carrier frequency offset estimate, and the remaining timing offset estimate to a global synchronization controller. This invention's wireless continuous communication synchronization method and system utilizes the timing estimate L estimated by the time-domain preamble sequence to locate the data stream. The global synchronization controller then corrects the relationship between the data stream frequency and its location based on the carrier frequency offset estimate, the remaining carrier frequency offset estimate estimated by the frequency-domain auxiliary pilot, and the remaining timing offset estimate.

The invention provides a ZC sequence-based OFDM (Orthogonal Frequency Division Multiplexing) system synchronization method, which comprises the following steps of: firstly constructing two ZC sequences ZC1 and ZC2 with different roots, then valuing and arranging the ZC1 sequence and the ZC2 sequence to obtain a training sequence, carrying out IFFT (Inverse Fast Fourier Transform) on the training sequence, adding a cyclic prefix to a data frame, then sending the training sequence by a sending end and transmitting the training sequence through a channel, and calculating the cross correlation between the receiving end data and the local training sequence, finally selecting a symbol synchronization position according to a cross correlation calculation value, and after the synchronization position is determined, estimating the carrier frequency offset. According to the scheme of the invention, accurate symbol synchronization and frequency offset estimation can be carried out in a large-fading and low-signal-to-noise-ratio wired channel environment, the synchronization reliability is enhanced, and the operand is reduced.

The invention discloses a high-spectral-efficiency and high-speed FTN (Fourier Transform Network) transmission method based on pseudo code auxiliary carrier synchronization, which belongs to the field of high-frequency wireless communication, and comprises the following steps: a transmitting end composites a low-speed pseudo code pilot signal into a high-speed FTN signal by adopting a frequency division multiplexing mode to obtain a composite signal and outputs the composite signal; a receiving end performs down-conversion on the received composite signal, and the composite signal is separated by a filter to obtain a low-speed pseudo code pilot frequency sequence and a high-speed FTN sequence; carrying out carrier frequency offset estimation based on the low-speed pseudo code pilot frequency sequence to obtain a frequency offset estimation value; performing frequency offset compensation on a receiving end carrier by adopting the frequency offset estimation value to obtain a compensated high-speed FTN sequence; and carrying out symbol estimation on the compensated high-speed FTN sequence by adopting a forward backtracking continuous symbol sequence detection algorithm to obtain a received signal. According to the invention, the receiving sensitivity and the system robustness can be ensured while high-spectrum-efficiency transmission is realized.