53 results about "Amplifier nonlinearity" patented technology

The invention discloses a power adaptive digital pre-distortion method, system and device based on sparse GRU and a medium. The method comprises the steps that input and output signals under different powers are collected, a composite feature vector is constructed through amplitude normalization and phase alignment, and a pre-distortion training target is generated in combination with indirect learning; constructing a sparse GRU neural network, introducing L1 regularization constraint, and obtaining a sparse pre-distortion model through joint optimization of mean square error and sparse constraint; partial weight updating is realized based on power grading, and weight fusion output is carried out during power interval switching so as to complete power adaptive optimization; pruning and compressing the sparse GRU model and then deploying the sparse GRU model in a pre-distortion module to compensate the nonlinearity of the power amplifier; according to the method, the model complexity is reduced through rarefaction, the dynamic working condition stability is improved through a power adaptive mechanism, pruning compression adapts to low-power-consumption hardware, high precision, low complexity and adaptive capacity are considered, and the method is suitable for the low-power-consumption and high-performance requirements of a broadband wireless communication system.

The present invention provides a new pilot pattern and channel estimation method involving such pilot for mmWave OTFS systems in high mobility scenarios with non-ideal power amplifier, which is applicable in the fifth generation (5G) and beyond networks. The pilot pattern for communication signal in wireless communications involving mmWave systems with non-ideal power amplifier comprises signal including a pilot signal element, information-bearing symbol and zero as guard, wherein, position of pilot and guard are arranged to combat the effect of inter symbol interference (ISI) from nonlinear impairment of the power amplifier for accurate channel estimation.

Methods and systems for NN-based digital pre-distortion for digital envelope tracking power amplifiers. A computer-implemented method includes receiving a measure of a digital envelope at a digital pre-distortion module having a neural network (NN)-based digital pre-distortion structure for digital envelope tracking (DET), receiving a transmit signal at the digital pre-distortion module, inputting the measure of the digital envelope and the transmit signal into the NN-based digital pre-distortion structure to produce a pre-distorted transmit signal, adjusting nonlinearity compensation of a power amplifier based on the measure of the digital envelope, and using the adjusted nonlinearity compensation of the power amplifier to produce an output signal.

The invention provides an OTFS (Orthogonal Time Frequency Space) channel estimation method based on a bidirectional gating loop unit (BiGRU) and a multi-head attention mechanism, and belongs to the technical field of channel estimation. The method comprises the following steps: determining time delay-Doppler domain parameters according to a channel scene, and constructing a TDL (Tap Delay Line) channel model; designing a time-frequency domain pilot frequency structure; carrying out time-frequency domain modulation on a sending signal and adding high-power amplifier (HPA) nonlinear distortion; obtaining an initial channel state by using LS estimation; a BiGRU network and multi-head attention mechanism joint model is constructed, and channel state prediction is realized through bidirectional time sequence feature extraction and multi-dimensional attention weight distribution; and time delay-Doppler domain channel response reconstruction is completed by using the optimized model. Bidirectional dependency of channel time-varying features is captured through BiGRU, and a multi-head attention mechanism is combined to enhance the key path feature extraction capability, so that the channel estimation precision in a high-mobility scene is remarkably improved, and the influence of HPA nonlinear distortion on the system performance is effectively inhibited.

The invention discloses a pre-distortion calibration method and system based on a single chip microcomputer, a medium and a product, and relates to the field of radio frequency front ends. The method comprises the following steps: extracting an instantaneous amplitude value of an input signal sequence to obtain a first envelope to represent instantaneous nonlinearity; the periodic average power of the input signal is calculated and filtered through timer interruption, and a second envelope representing the heat effect is obtained. According to the method, the first envelope and the second envelope serve as double indexes, the preset two-dimensional lookup table is inquired, so that the pre-distortion calibration coefficient capable of being matched with the instantaneous nonlinearity and the thermal memory effect of the power amplifier at the same time is determined, and the input signal is calibrated. In addition, a feedback signal output by the power amplifier is obtained to calculate a distortion calibration error, and the two-dimensional lookup table is adaptively updated according to the error. According to the scheme, a composite calibration model is constructed on a low-cost single-chip microcomputer platform, and the accuracy and stability of nonlinear pre-distortion calibration of the power amplifier are guaranteed.

The invention discloses a precoding matrix optimization method based on a multi-user MIMO system, and the method comprises the steps: obtaining a channel matrix through a base station channel estimation module, and defining a non-convex optimization problem of multi-user precoding; converting a non-convex optimization problem into a quantum annealing solvable secondary unconstrained binary optimization model, and dynamically reflecting a channel interference relationship through quantum bit coupling strength; designing a post-processing algorithm, compensating quantum hardware noise by using gradient descent and a nonlinear function of a power amplifier, and optimizing an output pre-coding matrix; the method overcomes the limitation that a traditional method is prone to falling into local optimum in non-convex optimization, can adapt to complex interference scenes in real time, and is suitable for a current 5G environment and a future wireless communication system.

A communication device comprises: a digital predistortion (DPD) circuit; a digital-to-analog converter (DAC) configured to convert output signals of the DPD circuit into analog signals; a power amplifier configured to amplify the analog signals; and an antenna configured to transmit the amplified analog signals, wherein the DPD circuit may be configured to: generate first predistortion signals by performing a convolution operation on digital signals of a reference time unit over a time interval including a first set of time units before the reference time unit and a second set of time units after the reference time unit; generate second predistortion signals by performing predistortion on the digital signals; and generate the output signals of the DPD circuit on the basis of the first predistortion signals and the second predistortion signals.

The present invention relates to a method for minimizing energy consumption of a RIS-assisted communication system, which belongs to the field of B5G cellular communications. Taking into account user communication rate constraints and RIS discrete phase shift constraints, and with minimizing total system power consumption as the optimization goal, a system model is established for a RIS-assisted multi-user multi-input single-output communication system with hardware damage; the original problem is transformed into an equivalent convex optimization problem using the S process and the successive convex approximation method; and the convex optimization problem is solved based on a semidefinite relaxation method and an alternating optimization algorithm. The present invention can ensure good robustness and reduce base station transmission power. The deployment of RIS effectively alleviates the impact of channel uncertainty and non-ideal hardware, and is suitable for actual communication scenarios where the transceiver has hardware damage such as I / Q imbalance and amplifier nonlinearity.

The invention discloses a system for generating 532nm green light through frequency doubling of 1-micron narrow-linewidth nanosecond laser, which effectively inhibits the nonlinear threshold of an optical fiber amplifier, realizes high-power output of 1-micron narrow-linewidth nanosecond laser while ensuring high light beam quality, and realizes high-efficiency frequency conversion of a pumping nonlinear crystal. The all-fiber polarization-maintaining cascade amplifier comprises a fiber laser seed source system, a fiber pre-amplification device and a fiber main amplifier. The fiber laser seed source system adopts a direct modulation semiconductor laser, the main amplifier adopts a polarization-maintaining conical fiber as a gain medium, the all-fiber polarization-maintaining cascade amplifier outputs narrow linewidth nanosecond laser, and each part adopts an all-fiber welding mode; according to the solid cavity external frequency doubling device, narrow linewidth nanosecond laser is collimated and focused through a lens system, the polarization extinction ratio is improved through combination of a half slide and a polarization slice, meanwhile, the power of injection pump light is adjusted, finally, the laser is coupled into an LBO crystal, and the size of a light spot and the temperature of the crystal are controlled to achieve high-efficiency frequency doubling green light output.

The invention discloses a multi-satellite large-scale MIMO (Multiple Input Multiple Output) downlink precoding method and a multi-satellite large-scale MIMO downlink precoding system considering power amplifier nonlinearity. According to the method, different time delays and Doppler frequency shifts of different satellite signals arriving at a user terminal are considered, and pre-compensation is carried out on each satellite sending signal; the input and output characteristics of the satellite side nonlinear power amplifier are modeled by using the polynomial model; establishing an optimization problem to jointly design a precoding vector and a receiving vector; the signal interference noise distortion ratio in the optimization problem considers interference and distortion from other satellites, interference and distortion in the satellite and a noise item; and converting a sum rate maximization problem into a weighted mean square error minimization problem for solving. And a traditional iteration updating step is further mapped into a learnable network layer structure through a deep expansion algorithm, so that the calculation complexity is reduced. Compared with the traditional method, the method provided by the invention is more in line with the actual transmission condition, can improve the system performance and reduce the online calculation overhead, and is suitable for the precoding design in a multi-satellite communication scene.

This invention discloses a pre-equalization compensation method for a terminal in a TDD-OFDM direct conversion system with known transmitter IQI and nonlinear parameters. The method includes: the base station cyclically sending P different training sequences to the terminal; the terminal using a sliding window least squares-based channel state information tracking algorithm to track and estimate the channel state information, where δ is a threshold representing the correlation of the channel within adjacent symbol periods; and pre-equalization compensation performed directly at the terminal. Using the pre-equalization compensation algorithm, a modified data sequence can be obtained and sent to the base station. This invention considers three factors in wireless communication systems: I-path and Q-path imbalance caused by the non-ideal nature of analog components in RF transceivers, power amplifier nonlinearity, and multipath channels. It enables distributed processing within the cell, effectively reducing the demodulation burden on the base station and has wider applicability than traditional compensation methods.

A method for wireless communication by a user equipment (UE) includes transmitting, to a network node, a first message indicating a capability of the UE to transmit a multiplexed low peak-to-average power ratio (PAPR) demodulation reference signal (DM-RS) and a high PAPR reference signal (RS) within a single slot. The method also includes multiplexing, associated with the capability, the low PAPR DM-RS with the high PAPR RS within the single slot. The method further includes transmitting, to the network node, the multiplexed low PAPR DM-RS and high PAPR RS within the single slot.

A signal processing apparatus and related transceiver circuit are disclosed. The signal processing apparatus includes a power amplifier circuit and a transceiver circuit. The transceiver circuit is configured to generate multiple composite signals each having a respective one of multiple inverted intermodulation product terms. The power amplifier circuit includes multiple power amplifiers each configured to amplify a respective one of the composite signals. By including the inverted intermodulation product terms in the composite signals prior to amplifying the composite signals, it is possible to offset intermodulation product terms inherently caused by nonlinear responses of the power amplifiers, thus helping to reduce spectrum degradation in the signal processing apparatus.

This invention belongs to the field of wireless communication and signal processing technology, and relates to a digital predistortion method, system, and application for power amplifiers in shortwave communication systems. This invention can cover the wide dynamic range of the power amplifier's operating range in shortwave communication systems, maintaining excellent linearization compensation across the entire power range. It effectively improves modulation signal distortion, spectral broadening, and adjacent channel interference, significantly reducing the system bit error rate and improving the quality of the transmitted signal, thus meeting the requirements for spectral and linearity specifications. This invention eliminates the need for multiple predistortion models and complex switching logic, greatly reducing system implementation complexity and storage resource overhead. When power levels switch or the signal envelope changes rapidly, it avoids additional distortion introduced by abrupt changes in predistortion parameters, ensuring continuous and stable linearization. Furthermore, this invention supports online adaptive updates, enabling real-time adaptation to changes in the nonlinear characteristics of the power amplifier, improving system robustness and environmental adaptability.

The application discloses a gradient field nonlinearity compensation method and system in a low-field magnetic resonance imaging system, and belongs to the technical field of magnetic resonance imaging. The application aims at the gradient field distortion problem caused by the nonlinearity of a gradient power amplifier and the thermal memory effect in a low-field magnetic resonance system, and provides a real-time dynamic compensation scheme integrating feedforward calibration and thermal effect modeling. The application calibrates the nonlinearity error of a gradient current through a pre-scan sequence, generates an initial feedforward lookup table, establishes a thermal model representing the thermal dynamic behavior of the gradient power amplifier, dynamically corrects the feedforward table according to the influence factor of the thermal memory effect estimated in real time according to historical workloads, and iteratively corrects the feedforward table and the thermal model through adaptive filtering technology. The application greatly reduces the computing power requirement of the compensation algorithm, can track the dynamic thermal drift of the gradient field in real time, solves the gradient field nonlinearity problem from the signal source, and significantly improves the geometric fidelity of a low-field magnetic resonance image.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a network entity, a reference signal. The UE may transmit, to the network entity and via a feedback channel, digital pre-distortion (DPD) information that is based at least in part on the reference signal, wherein the DPD information indicates an estimate of non-linearities of a power amplifier at the network entity based at least in part on the reference signal. Numerous other aspects are described.

The application discloses an anti-power amplifier nonlinearity original AI communication system, which comprises a transmitting end, a channel and a receiving end, wherein the transmitting end comprises a trained learnable back-off mapper LBOM, which maps an input coded bit stream into a power back-off symbol stream; the LBOM performs joint optimization on constellation distribution and input power back-off parameters through training; the channel transmits the sending symbol distorted by the power amplifier nonlinearity; when the computing power of the receiving end is limited, the receiving end adopts a neural network demapper ND to demap the symbol and signal-to-noise ratio information output by the channel into a log likelihood ratio, and information bits are obtained through BP decoding; when the computing power of the receiving end is sufficient, the receiving end adopts an IDD module to receive the symbol and signal-to-noise ratio information output by the channel, and joint iterative decoding is realized through mutual transmission of extrinsic information between submodules to obtain information bits; the IDD module comprises a neural network demapper iDemapper submodule and a BP decoder iDecoder submodule.

The invention discloses a D-type power amplifier nonlinear behavior modeling method and system based on an RRU network, belongs to the technical field of wireless communication, and solves the problems that in the prior art, a traditional model is difficult to accurately represent nonlinear characteristics of a D-type power amplifier and the like. The method comprises the following steps: firstly, carrying out dynamic feature extraction on an input complex signal by adopting a filter with an adjustable weight, then integrating the dynamic feature and the current input, carrying out processing by utilizing an internal reference standardization factor, inputting the standardization feature into an improved RRU (Radio Remote Unit) network, and carrying out cyclic state alignment and residual error type updating on the network through a cyclic state alignment and residual error type updating mechanism. Carrying out deep learning on the nonlinear time sequence dynamic state of the signal; and finally, accurately predicting the output behavior of the D-type power amplifier through an output layer and a reference reduction step. According to the method, the advantages of adaptive filtering, internal reference standardization and the RRU network are combined, the accuracy and robustness of the nonlinear model of the D-type power amplifier are remarkably improved, and a foundation is laid for applications such as efficient digital pre-distortion.

Disclosed is a method and system for forward synthesis of a digital predistortion nonlinear model derived from a circuit description, used for nonlinear modeling of a power amplifier. The method includes establishing a frequency band-continuous time-domain expression, transforming the frequency band expression to a baseband expression, and transforming the baseband-continuous time-domain expression to a baseband-discrete time-domain expression. The present disclosure can obtain the DPD nonlinear model by forward synthesis, provide an accurate model structure and initial parameter values for establishing the RF power amplifier model in the power amplifier nonlinear predistortion technology, make full use of the prior knowledge of the RF power amplifier system to obtain the nonlinear model structure that best conforms to the physical essence, and directly obtain the minimum memory depth and nonlinear order, and can be integrated into an RF power amplifier circuit simulation software.

This application discloses a digital predistortion (DPD) implementation method, system, device, and storage medium, relating to the field of radio frequency communication technology. The method includes: when the soft core receives a calibration start command, it first sends a sinusoidal calibration signal to the FPGA platform, triggering its initial calibration of the transmission link; after receiving a calibration confirmation signal from the FPGA, the soft core reads the pre-stored initial training modulation signal from its internal memory and sends it to the FPGA platform as transmission data; subsequently, it reads the feedback data after nonlinear distortion by the power amplifier from the FPGA via a high-speed bus; based on this feedback data and the initial training signal, the soft core iteratively updates the digital predistortion compensation parameters and updates the transmission data; the FPGA performs stable compensation on the power amplifier (PA) based on the updated transmission data. This method, through the collaboration of the FPGA and the soft core, tightly couples calibration, acquisition, caching, and updating, utilizes on-chip high-speed storage to avoid external memory access, and combines pipelined processing to significantly improve DPD accuracy, iteration efficiency, and resource utilization.

Apparatuses and methods for negotiation and signaling for cooperative control of power amplifier nonlinearity are disclosed. At least some example embodiments may allow signaling to support the design and deployment of cooperative control of power amplifier nonlinearity for digital pre-distortion (DPD) applications in user equipment and digital post-distortion (DPoD) applications in network nodes, where digital pre-distortion may be used to control out-of-band transmissions (e.g., adjacent channel leakage ratio (ACLR)), and digital post-distortion (DPoD) applications in network nodes. And digital post-distortion may be used to control in-band transmission (e.g., error vector magnitude (EVM)).

This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for non-linearity estimation techniques for digital post distortion (DPoD) in a wireless system. In some aspects, a first wireless device may estimate a power amplifier (PA) non-linearity associated with a second wireless device using select signaling from the second wireless device. For example, the first wireless device may use a received signal to estimate the PA non-linearity if a dynamic power range associated with the signal triggers the estimation of the PA non-linearity (such as if the dynamic power range associated with the signal satisfies, or is expected to satisfy, a threshold dynamic power range). If the dynamic power range of the signal triggers the estimation of the PA non-linearity, the first wireless device may introduce DPoD to signaling received from the second wireless device in accordance with the estimation of the PA non-linearity.

Aiming at the problem of signal nonlinear distortion caused by nonlinear characteristics of a power amplifier in satellite communication, the invention provides a generalized linear dual-mode switching blind equalization algorithm based on a third-order truncated Volterra structure, and the technical scheme and the application effect are expanded according to the following steps S1 to S3: S1: initializing parameters of a generalized linear blind equalizer based on the third-order Volterra structure; s2, taking a modified constant modulus algorithm and a decision-oriented least mean square algorithm in the linear blind equalization field as theoretical basis, combining signal processing characteristics of a third-order truncated Volterra nonlinear model, deriving to obtain two generalized linear equalizer tap updating formulas suitable for the nonlinear model, and providing algorithm support for a dual-mode equalization mechanism; s3, adopting a staged adaptive equalization strategy to construct a switching mechanism: in an equalization initial stage, using a generalized linear correction constant modulus algorithm of a nonlinear channel, and utilizing a rapid convergence characteristic of the algorithm to realize rapid reduction of a mean square error; and when the equalization process reaches a preset judgment condition, automatically switching to a generalized linear judgment guide algorithm of a nonlinear channel, further reducing the steady-state error through judgment feedback, and considering both the convergence speed and the equalization precision.

The application discloses a kind of based on two-stage attention neural network's down-sampling DPD method and device, method includes: using memory polynomial method determines rough estimate DPD parameter;Based on a plurality of input sample signals and each input sample signal corresponding rough estimate DPD signal constructs sample set;Wherein, each input sample signal corresponding rough estimate DPD signal is determined based on the input sample signal and rough estimate DPD parameter;Utilize sample set training DPD neural network model, and according to the model after training realizes down-sampling DPD signal estimation;Utilize sample set training model includes: input input sample signal into model, to make model output the input sample signal corresponding output DPD signal;According to the difference between the output DPD signal and rough estimate DPD signal corresponding to input sample signal, incremental training is carried out to DPD neural network model, reduce the calculation cost, improve the power amplifier nonlinear correction efficiency.

The invention discloses a power amplifier nonlinear compensation method and device combining amplitude-phase grouping modulation and data driving. At a transmitter side, bit information is borne by adopting a packet modulation technology with amplitude-phase constraints, and a frame structure sequence is constructed by using nonlinear compensation pilot symbols and data symbols. At a receiver side, a distorted data symbol is reconstructed through amplitude-phase constraint to obtain a preliminarily compensated signal sequence, and a power amplifier nonlinear distortion inverse model is trained offline to obtain a coarse estimation parameter. And carrying out parameter initialization on an online power amplifier nonlinear distortion inverse model by using the parameter through a transfer learning technology, carrying out online training by using a known nonlinear compensation pilot frequency sequence to obtain a fine estimation parameter of the inverse model, compensating a nonlinear distortion data signal through the inverse model, and demodulating to obtain emission information. According to the invention, more accurate power amplifier nonlinear compensation is realized, the resource overhead of the transmitting and receiving end is reduced, and the power efficiency and the information transmission performance of a wireless communication system are remarkably improved.

The application discloses a kind of amplitude-phase grouping modulation-oriented received signal reconstruction methods, it is applicable to communication system receiving end, the amplitude-phase grouping modulation signal of distortion caused by power amplifier nonlinear amplification is reconstructed.The method is first to the frequency domain equalization of received signal, and eliminate the influence of power amplifier linear amplification;Then, the phase of received signal is adjusted, and demodulates additional phase;Subsequently, the amplitude of received signal is revised;Then, based on least square criterion, signal reconstruction optimization problem model is constructed, and least square optimization reconstruction is executed.Afterwards, additional phase demodulation, amplitude adjustment and least square optimization reconstruction are iteratively executed until the preset iteration number is reached, so as to obtain high-quality reconstructed signal.The application can effectively deal with nonlinear distortion at the receiving end of the communication system, realize high-quality signal reconstruction, thereby significantly improving the overall performance and power efficiency of the communication system.

The disclosed signal nonlinear distortion compensation method, model, and communication system relate to the wireless communication technology field. In this disclosure, a preset nonlinear compensation fusion model is used to perform DPD processing, CFR processing, and error compensation processing on an initial OFDM signal to obtain a nonlinear distortion-compensated initial OFDM signal. In this nonlinear compensation fusion model, the BL-DPD module, BL-CFR module, and error compensation module are arranged in parallel, avoiding the technical drawbacks of the prior art, where the DPD module is applied after the CFR module, which increases the requirements for the ADC / DAC sampling rate and the requirements for hardware and algorithm convergence speed, thereby increasing the difficulty and cost of system implementation. This not only reduces the requirements for the ADC / DAC sampling rate, but also improves the DPD compensation ability for power amplifier nonlinearities, thereby improving the communication and sensing performance of the OFDM system.

According to an aspect, an apparatus may comprise a digital pre-distorter, DPD, circuitry including at least one first-order infinite impulse response, IIR, filter and at least one second-order IIR filter. The apparatus may further comprise a power amplifier, at least one processor and at least one memory comprising instructions which, when executed by the at least one processor, cause the apparatus at least to compensate for non-linearities in the power amplifier by using the at least one first-order IIR filter and the at least one second-order IIR filter.

Method for identifying individual radiation sources under digital predistortion of power amplifiers. The present invention relates to a method for identifying individual radiation sources. The purpose of the present invention is to solve the problem that existing power amplifier linearization technologies weaken the nonlinear effect of power amplifiers while improving signal quality, resulting in a decline in the performance of individual radiation source identification. The process is as follows: First, obtain a trained digital predistortion trainer; Second, extract multi-domain features from the radiation source signals output by the labeled digital predistortion trainer. The process is as follows: 2.1 Extract contour integral bispectrum features; 2.2 Extract horizontal visibility graph features; 2.3 Extract individual features based on intrinsic time-scale decomposition; Third, obtain a trained SincNet network; Fourth, extract multi-domain features from the radiation source signals to be measured output by the digital predistortion trainer; Fifth, identify the category of the individual signal of the radiation source to be measured after predistortion. The present invention is used in the field of individual radiation source identification.