55 results about "Amplifier nonlinearity" patented technology

A method and apparatus are provided for automatic data rate control in wireless communication systems, such as wireless LANs. A data rate controller adapts a transmission rate of said data based on a signal quality and a transmit power level. The data rate controller can also adapt the transmission rate based on one or more of amplifier non-linearities, anticipated signal quality for a next frame transmission, regulatory emission limits and data rate advice. The data rate advice will decrease a data rate if a current signal quality is below a minimum required signal quality for a given data rate and increase a data rate if a current signal quality is above a minimum required signal quality for a given data rate. A probation mechanism allows a higher rate to be evaluated before switching to the higher rate permanently. A retry balance mechanism forces a rate fallback when a number of failed transmission exceeds a predefined threshold. A rate fallback feature reduces the transmission rate when a number of failed transmission exceeds a predefined threshold.

The invention discloses a power amplifier linearization correcting circuit and method based on multi-channel feedback, relates to a linearization technology in the technical field of communication, and aims to provide a power amplifier linearization correcting circuit and method capable of self-adaptively regulating a predistortion parameter of a system by tracking the linearization characteristic of a radio frequency power amplifier. The power amplifier linearization correcting method is technically characterized in that a signal output by a power amplifier is subjected to frequency spectrumdivision and is coupled to a feedback system by utilizing a plurality of paths of channels; a data recovery circuit recovers a plurality of paths of feedback information to form a path of signal; a predistortion trainer calculates the predistortion parameter by utilizing a baseband signal and a recovered feedback signal; a predistortion trainer A adds a predistortion signal complementing a nonlinear distorted signal of the power amplifier according to the predistortion parameter; and the predistortion signal in the baseband signal is counteracted in the power amplifier, thereby realizing the linearization correction of the power amplifier. The invention is mainly used for nonlinear predistortion correction of a radio frequency signal emission system.

The invention provides methods and devices for estimating power amplifier nonlinearity using simple correlation techniques. Methods and devices of the invention can monitor a power amplifier that has digitally modulated inputs and an output containing more than one signal stream. A preferred method of the invention creates a test signal by forming the products of several pseudorandom noise sequences from the digitally modulated inputs to the power amplifier. Nonlinear contributions of the power amplifier output are determined by cross-correlating the test signal and the total output signal of the power amplifier. In preferred embodiments, the determined nonlinear contributions of the power amplifier are used to introduce corrective predistortion in the power amplifier.

The invention discloses a self-adaptive digital pre-distortion linear system of a radio frequency power amplifier, comprising a base band processing module, a digital pre-distortion compensation module and a radio frequency power amplifier; the digital pre-distortion compensation module is connected to the middle of the base band processing module and the radio frequency power amplifier and used for bettering the distortion caused by the nonlinearly amplification of the radio frequency power amplifier. The invention provides the complete and optimized self-adaptive digital pre-distortion linear system structure of the radio frequency power amplifier capable of supporting various pre-distortion models; the invention has the advantages of being wide in applicable range, simple in structure and lower in implement cost at the fixed point.

The invention relates to a method for implementing an open-loop digital baseband pre-distorter based on polynomial, which is a method for implementing the digital baseband pre-distorter, particularly relates to a method for implementing the open-loop digital baseband pre-distorter based on the polynomial suitable for various kinds of digital audio-video broadcasting systems such as DAB, DRM and DVB. The method comprises generating the cubic term and the quintic term of a complex coefficient of a primary digital baseband signal by using the universal mathematical model-polynomial model of various kinds of radio frequency power amplifier, and adjusting the amplitude and the phase of the complex coefficient through a man-machine interface to counteract the cubic term and the quintic term produced nonlinearly by the final radio frequency power amplifier. The invention is used for actual measurement for small-power experiment emitting system, and the result shows that the invention can well compensate for the nonlinearity of HPA, inhibit in-band and out-band distortion in a larger degree, and obviate the complex radio frequency feedback loop. The invention has simple implementation, obvious effect, and is suitable for various kinds of digital audio-video broadcasting systems.

A method and system provide the ability to measure a transmission performance characteristic. A signal is received and demodulated. An ideal signal is generated from the demodulated signal. The received signal is coherently averaged to reduce noise. The performance characteristic is the estimated TWTA nonlinearity from a difference between the coherently averaged ideal signal and received signal.

A method and system provide the ability to measure transmission performance characteristics. A signal is received and demodulated (1302). An ideal signal (1320) is generated (1304) from the demodulated signal. The received signal is coherently averaged (1324/1326) to reduce noise. The performance characteristic is the TWTA nonlinearity estimated from the difference between the coherently averaged ideal signal and the received signal.

The invention discloses a hybrid pre-distortion linearizer with wide application range. The hybrid pre-distortion linearizer comprises a power divider and a synthesizer, wherein output ports of the power divider are in one-to-one connection with input ports of the synthesizer through a series transmission type analog pre-distortion circuit or a parallel transmission type analog pre-distortion circuit. The linearizer synthesizes multiple nonlinear signals with different characteristics to obtain the required spectrum and phase pre-distortion signals, overcomes the shortcomings that independent series and parallel transmission type analog pre-distortion circuits can only produce pre-distortion signals suitable for solid-state power amplifiers and most reflection-type pre-distortion circuits can only produce pre-distortion signals suitable for millimeter wave traveling-wave tube power amplifiers, can realize the nonlinear pre-distortion linearization for the millimeter wave traveling-wave tube power amplifiers and the solid-state power amplifiers, has wide application range, and is suitable for being popularized in the technical field of millimeter wave linearization.

The invention is specific to the problem of PAPR (peak to average power ratio) presented by OFDM (orthogonal frequency division multiplexing) modulation of 60 GHz millimeter wave communication system, and provides a method of lowering OFDM signal PAPR by using selectivity mapping combined with LDPC (low density parity check) to generate matrix high density character. By adding a little bit information, PAPR of the millimeter wave OFDM transmission signal is effectively lowered. In a big rate situation, a construction plan of improving an LDPC non-systematic code is provided, which can remarkably lower PAPR and effectively improve the transmission performance in the case of nonlinearity power amplifier distortion of 60 GHz millimeter waves system. Compared with the traditional coding scheme, the invention can remarkably lower PAPR, improve the transmission performance of millimeter wave signal in the presence of device nonlinearity and excels other coding scheme in aspect of anti-power amplifier PA nonlinearity. At the same time, the non-systematic code which is designed and constructed in the method and device can still have a fine performance when the coding rate is big. The arithmetic implementation of the non-systematic code is simple, and parallel computation can be used by the non-systematic code, so that the method and the device of lowering 60 GHz communication system PAPR (peak to average power ratio) based on LDPC (low density parity check) coding mechanism has great practical value in high-speed millimeter waves OFDM system.

A method of dynamically calculating and updating the Volterra kernels used by the Digital Pre Distortion engine based on output power, input signal bandwidth, multicarrier configuration, frequency response and power amplifier temperature. A dominant Volterra kernels searching DSP engine based on innovation bases with minimum RMS error selection is implemented to continuously update the Volterra kernels set used in DPD to model the power amplifier non linear behaviours.

A nonlinear distortion compensating circuit for compensating for a nonlinear distortion caused by a power amplifier for amplifying an input signal has a power calculator for calculating a power value of the input signal, an operating point setting unit for calculating an apparent power value from temperature information, supplied from an external source, representative of the measured temperature of the power amplifier and the power value calculated by the power calculator, based on a relationship, given beforehand to the operating point setting unit, between input vs. output characteristics of the power amplifier and the temperature of the power amplifier, an inverse characteristics calculator for calculating an inversion of the nonlinear distortion from inverse characteristics data, given beforehand to the inverse characteristics calculator, and a complex multiplier for adding the inversion calculated by the inverse characteristics calculator to the input signal.

The invention relates to a nonlinear function generator, a function transformer and a general nonlinear corrector, belonging to the technical fields of signal transformation and automatic control and measurement. The nonlinear function generator has the following types: an easy type and a synthetic type, inverted and inphase broken line types, inverted and inphase triangular wave synthesis types and a sine-wave synthesis type, and the like. The function transformer comprises the nonlinear function generator and an input and output gain controller which adopts a bipolar adjustable-gain amplifier, the nonlinear corrector has three types, i.e. a direct feed type, a feedback type and a combined type and comprises a weighted combiner, the function transformer and an output synthesizer, the general nonlinear corrector comprises a zero-bit adjustment circuit and the nonlinear corrector, and a (general) nonlinear corrector of a high impedance type adopts the (general) nonlinear corrector of a pre-voltage follower.

The present invention discloses an MIMO system transmitting end digital pre-distortion optimization method based on an input sequence. The method comprises a step of using a memory polynomial model to characterize the power amplifier of a transmitting end, a step of inputting a predetermined input sequence to the model of the power amplifier such that the input signals between different antennas have association, simplifying the memory polynomial models of multiple antennas as similar with the memory polynomial model of a single antenna, and estimating a corresponding coefficient, and a step of separating a crosstalk coefficient and the coefficient of the power amplifier according to the coefficient estimated by the input sequence, and compensating the crosstalk influence and the nonlinear influence of the power amplifier. Through optimized design of the input sequence, a nonlinear model is simplified, and the computational complexity is reduced.

The invention discloses a variable vector hybrid superimposed predistortion linearization method suitable for improving the linearity of a microwave millimeter wave solid-state power amplifier. According to the variable vector hybrid superimposed predistortion linearization method, on the basis of the working mechanism of the traditional diode reflected predistortion linearization, an effect of phase compression generated by gain expansion with the increase of the input power is realized by using the variable vector hybrid superimposing principle, good port standing wave is realized, and the purpose compensating the nonlinear distortion of the solid-state power amplifier within the microwave millimeter wave broad band is realized. By adoption of the variable vector hybrid superimposed predistortion linearization method, the defect that the traditional reflected simulated predistortion technology can only generate phase expansion with the increase of the input power and is only applicable to linear traveling wave tube power amplifiers, breaks through the limitation of the reflected predistortion circuit bandwidth; and the variable vector hybrid superimposed predistortion linearization method has the advantages of novel structure, simple and compact structure, easy processing and assembly, and is suitable for popularization and application in the technical field of microwave millimeter wave predistortion linearization.

Various embodiments provide for systems and methods for increased linear output power of a transmitter. An exemplary wireless communications system for transmitting an input signal comprises a predistorter module, a GaN power amplifier, a coupler, and an antenna. The predistorter module is configured to detect existing distortion by comparing the input signal to a feedback signal and generate a correction signal. The predistorter may adaptively adjust its operation to minimize the existing distortion due to GaN power amplifier nonlinear characteristics. The result is that the GaN power amplifier may send a power signal of improved linearity to the antenna. The coupler is configured to sample the amplified signal from the GaN power amplifier to generate the feedback signal. The antenna is configured to transmit the amplified signal.

Methods and apparatus for facilitating wireless communication using digital Quadrature Amplitude Modulation are disclosed. A mapping module electronic component of a wireless communication device utilizes a signal constellation for quadrature modulating a signal for transmission or quadrature demodulating a received signal. The signal constellation includes multiple constellation symbols and associated bit sequences. Specific signal constellations are disclosed. The signal constellations may be obtained through an optimization procedure which accounts for both phase noise and power amplifier nonlinearity.

The invention provides a self-adaptive cancellation method based on a deep neural network, wherein the method comprises the steps: 1), defining a signal model received by a receiving antenna, wherein the signal model comprises transmitting signal power Pf, a nonlinear distortion function G[.] of a power amplifier and carrier center frequency fc; 2) defining a model of a nonlinear power amplifier; 3) performing nonlinear modeling on a target signal, and training a DNN network by using a large amount of data; 4) taking a signal generated after an original reference signal passes through a trained network as a new reference signal and inputting the new reference signal into a self-adaptive filter; and 5) comparing the signals before and after cancellation of the self- adaptive filter. According to the method, a large amount of training prior information is used for simulating the nonlinear characteristic of a radar jammer power amplifier, the interference problem is solved, the amplitude of the signal is directly estimated, and algorithm steps are reduced through a large amount of data.

The invention relates to an array antenna second harmonic interference field modeling and calculating method which includes steps of feeding for each array element of an array antenna through a voltage source; setting excitation amplitude and phase of each array element; calculating the excitation amplitude and the phase of each array element during transmission of the array antenna second harmonic according to non-linear response of amplifiers; splitting the surface of each array element triangularly and splitting a feeder linearly so as to acquire geometrical information of the surface of each array element and the feeder; and calculating induction current of the surface of each array element and the feeder according to the excitation amplitude and the phase of each array element during transmission of the array antenna second harmonic and the geometrical information of the surface of each array element and the feeder. By the array antenna second harmonic interference field modeling and calculating method, an interference field at interfered equipment during transmission of the array antenna second harmonic is acquired accurately, and then coupling level of a receiving end of the interfered equipment is acquired, so that support for suppressing and analyzing harmonic interference and improving interference resistance performance of sensitive equipment is offered.