28 results about "Qam modulation" patented technology

This invention relates to the field of unmanned aerial vehicle (UAV) communication technology, and in particular to a communication method for a dual-channel UAV line-of-sight (LAS) communication system. The method includes: acquiring communication quality, acquiring the optimal transmission frequency, acquiring the UAV's mission priority, transmitting video stream data, and performing multipath fading compensation steps. The method sets up high-frequency and low-frequency channels, calculates frequency quality indicators using signal-to-noise ratio (SNR), signal rate, and bit error rate (BER), and dynamically selects the optimal transmission frequency. Communication resources are allocated based on mission priority to ensure priority transmission of critical commands. Innovatively, differential geometry theory is used for multipath fading compensation, mapping the communication signal to a Riemannian manifold space, extracting fading features, and optimizing the processing. High- and low-frequency channel collaborative compensation is achieved, with mutual enhancement through received spectrum analysis and training sequence correction. Adaptive QAM modulation is supported, dynamically adjusting modulation parameters according to manifold curvature to construct a star-shaped multi-node communication network.

The application discloses a kind of adaptive QAM and OFDM bimodulus intracorporeal ultrasonic communication system and method based on channel estimation, belong to intracorporeal ultrasonic communication technical field, the transmitting end is configured with single carrier QAM modulation mode and multicarrier OFDM modulation mode, real-time evaluation intracorporeal ultrasonic channel quality in receiving end, according to the optimal modulation mode of evaluation result, according to the optimal modulation mode generation mode switching instruction, the mode switching instruction is sent to transmitting end, transmitting end according to the mode switching instruction seamlessly switches between single carrier QAM modulation mode and multicarrier OFDM modulation mode, so that transmitting end works in optimal modulation mode, the system and method can dynamically select optimal modulation mode according to intracorporeal channel real-time quality parameter, while ensuring that mode switching is reliably synchronized.

The application discloses a fast detection method based on regular hexagon modulation, which is suitable for regular hexagon QAM modulation in a communication system. The method comprises the following steps: constructing a communication system based on HQAM modulation, and configuring an additive white Gaussian noise (AWGN) channel; extracting HQAM modulation constellation point information and storing the information in a matrix form with axial coordinates as the matrix index; converting the signal through the AWGN channel into axial coordinates; searching in the information matrix by using the value of the axial coordinates; if the corresponding element exists in the matrix, symbol decision is performed; if the corresponding element does not exist in the matrix, it is judged whether the matrix indexes corresponding to the adjacent six hexagons exist in the information matrix; if the corresponding element still does not exist in the adjacent six hexagons, linear detection is used for symbol decision. The application provides a fast detection method based on regular hexagon modulation, so that symbol decision based on regular hexagon modulation can be more quickly and accurately detected.

The embodiments of the present application disclose a data transmission method, and an apparatus and a system thereof, which are compatible with the existing DSP framing schemes 400ZR+, 800ZR, and 800ZR+, are more conducive to hardware implementation, and can further be applied to future transmission scenarios using multi-wave or multi-subcarrier transmission, for example, 800 Gbps multi-subcarrier transmission using QPSK modulation, 1.2 Tbps multi-subcarrier transmission using 16-QAM modulation, 1.6 Tbps multi-subcarrier transmission using 16-QAM modulation, or even higher rate transmission scenarios such as 2.4 T / 3.2 T. The method comprises: sending W data frames, the number of symbols comprised in any one data frame in a polarization direction being 87552, each data frame comprising 12 subframes, and the number of symbols comprised in each subframe being 7296, where W is an even number.

The present invention provides a QAM modulation wireless communication method and system based on IM3. The wireless communication system includes a transmitting end and a receiving end. The transmitting end includes a transmitting signal source and a transmitting antenna connected in sequence. The receiving end includes a receiving antenna, a diode rectifier module, an IM3 modulator, a DC filter and a load. The IM3 modulator includes two branches connected in parallel between the signal transmission path and the ground line; an adjustable capacitor is provided on the first branch. An adjustable resistor is provided on the second branch. The present invention uses IM3 signals for communication, realizes zero energy consumption of wireless energy collaborative information transmission, reduces energy loss and prolongs system life, and is suitable for a variety of application environments. The present invention adopts a rectifier circuit with a single diode structure, and the IM3 signal used for transmission is generated by the diode itself, and does not require an additional oscillation circuit to generate it.

The invention relates to a semi-blind phase search method based on target planning in a probabilistic shaping CO-OFDM system. According to the method, a convergence area is set by taking an original constellation point after probability shaping as a center, and a hierarchical target planning strategy is adopted: a first layer takes maximization of signal points in the convergence area as a target, and a second layer takes minimization of a difference degree of probability distribution of a compensated signal and the original constellation point as a target. Meanwhile, test phases are selected by combining a staged test phase estimation strategy in the two-stage blind phase search algorithm, and the common phase noise is compensated by comparing the test phases. Simulation experiments show that compared with a traditional algorithm, the method can effectively suppress common phase noise of various constellation diagrams in different shapes under 16-QAM and 64-QAM modulation, the bit error rate performance is improved under the same signal-to-noise ratio, and meanwhile the spectrum utilization rate is remarkably improved.

The present disclosure proposes a transmitter and receiver for medical applications, wherein the transmitter comprises: an analog front end for receiving an analog signal of a neural electrode; a digital baseband processing module for digitizing and channel coding the analog signal to obtain a coded signal; a modulator for 16-QAM modulation of the coded signal to obtain a modulated signal; 16-QAM modulation is used to improve the scalable data rate; a plurality of target frequency signals are generated by a phase-locked frequency divider, and the target frequency signals are divided into a plurality of target sub-frequency signals; the phase of the modulated signal is adjusted based on the plurality of target sub-frequency signals to obtain a phase-adjusted signal, realizing multi-band data transmission within the transmitter; and finally a power amplifier amplifies the phase-adjusted signal, and the amplified phase-adjusted signal is transmitted to a transmitting unit so that the transmitting unit transmits a signal, realizing high-speed and low-power signal transmission.

The application is an improved selective mapping scheme (N-SLM) for an orthogonal frequency division multiplexing non-orthogonal multiple access passive optical network (OFDM-NOMA PON), and relates to the technical fields of optical communication and digital signal processing. In order to solve the problem of high peak-to-average power ratio (PAPR) of downlink signals in a non-orthogonal multiple access system using OFDM modulation, aiming at the shortcomings of high computational complexity of a traditional selective mapping (C-SLM) scheme and high error rate of explicit side information (SI) requiring additional bandwidth resources, the N-SLM scheme is proposed according to the characteristics of superimposed transmission of power domain NOMA multi-user data on subcarriers. Compared with the C-SLM scheme, the scheme has low computational complexity and does not need to send explicit SI. The application mainly includes the generation of alternative OFDM-NOMA signals at the sending end and the demodulation process at the receiving end. The sending end adopts information bit cyclic shift and inserts a few repeated coded check bits in the preamble part to generate multiple alternative bit information, thereby avoiding the explicit transmission of SI. All alternative bit information is sequentially subjected to QAM modulation, power allocation and OFDM modulation to generate multiple groups of OFDM signals with different power levels, which are arranged and combined to linearly superimpose multiple alternative OFDM-NOMA signals. The PAPR values of all alternative OFDM-NOMA signals are calculated, and the alternative OFDM-NOMA signal with the minimum PAPR is selected for subsequent signal processing. The receiving end respectively performs soft demodulation and hard demodulation on the QAM symbols corresponding to the repeated coded check bits and information bits, and performs corresponding reverse cyclic shift on the received information bits according to the check bits output by the repeated decoding. After the low-power-level data is subjected to successive interference cancellation (SIC) to obtain the corresponding information, the same processing process is performed.

The application provides a joint time-frequency domain equalization method under PSK and QAM modulation, which comprises the following steps: receiving an initial signal, sampling, obtaining an initial head scattered pilot, processing the initial head scattered pilot, realizing time domain cross-correlation and autocorrelation, respectively performing fast Fourier transform on a first processed signal and a second processed signal to obtain a third processed signal and a fourth processed signal, taking the third processed signal as a numerator and the fourth processed signal as a denominator to obtain a channel estimation frequency response, estimating a signal-to-noise ratio of the second processed signal to obtain a signal-to-noise ratio curve, calculating a signal-to-noise ratio estimation value according to a peak value in the signal-to-noise ratio curve and data variance calculated according to other data, combining the channel estimation frequency response to obtain a frequency domain equalization coefficient, processing second data and a tail scattered pilot in the initial signal to obtain a fifth processed signal, and combining the frequency domain equalization coefficient to obtain a time domain signal.

The invention relates to the technical field of digital transmitters, in particular to a digital millimeter wave transmitter which comprises a coupler, an orthogonal digital modulator and a digital-analog mixed mode Doherty power amplifier. Wherein the coupler is used for generating a broadband orthogonal signal and inputting the broadband orthogonal signal into the orthogonal digital modulator so as to realize QAM (Quadrature Amplitude Modulation) of the broadband orthogonal signal, and the orthogonal digital modulator inputs the modulated broadband orthogonal signal into the digital-analog mixed mode Doherty power amplifier so as to carry out power amplification on the modulated signal. According to the digital millimeter wave transmitter, through collaborative design of digital modulation and the mixed mode Doherty power amplifier, high system efficiency is achieved under the conditions of high peak-to-average ratio and high-power output, energy consumption is remarkably reduced, a quadrature amplitude modulation (QAM) modulation precision and signal linearity are improved by adopting the quadrature digital modulator and a precise amplitude / phase control mechanism, and the digital millimeter wave transmitter has the advantages of being simple in structure, low in cost and high in reliability. And high-speed data transmission is supported, and the requirement of a 5G system for high-capacity communication is met.

The invention relates to a signal phase keeping method and system in optical fiber communication, when coherent detection of received signals is carried out, the received signals are balanced in combination with frequency offset estimation (FOE), carrier phase recovery (CPR) and a plurality of neural networks, the carrier phase recovery is realized based on a Viterbi-Viterbi algorithm, and meanwhile, the plurality of neural networks provided by the invention can be used for carrying out coherent detection on the received signals. An input value, a neural node and an output value are complex numbers, and in a wireless channel equalization network, a CReLU activation function is used for complex value calculation for the first time. Compared with the prior art, the method is suitable for a complex signal generated by a QAM modulation format or coherent detection, the bit error rate performance more reliable than that of a real number neural network is achieved, and the method has the advantages of being low in complexity, reliable in bit error rate performance, high in sensitivity and the like.

Embodiments of the present application relate to the technical field of channel blind equalization, and particularly to a high-order QAM blind equalization method based on a cognitive communication system, comprising: constructing a system model of the cognitive communication system, the cognitive communication system using high-order QAM modulation; constructing a cost function for the first phase of the cognitive communication system under a high-order QAM modulation channel and an iterative formula for blind equalization in the first phase, optimizing the blind equalizer to optimize and minimize the cost function of the first phase; determining a switching threshold, and switching to the second phase when the function value of the cost function of the first phase is less than or equal to the switching threshold; constructing a cost function for the second phase of the cognitive communication system under a high-order QAM modulation channel and an iterative formula for blind equalization in the second phase, optimizing the blind equalizer to optimize and minimize the cost function of the second phase. This method effectively improves the convergence stability, convergence speed, and equalization quality of high-order QAM blind equalization.

The application discloses a kind of non-orthogonal multiple access system transmission methods based on dual-frequency index modulation.The method is first in the signal processing end of base station to the input multi-user bit stream signal respectively carries out specific M-QAM modulation and dual-frequency index modulation, then generates OFDM-DFIM (Dual Frequency Index Modulation) modulation signal using orthogonal frequency division multiplexing technology, finally compares the channel conditions of each user, and allocates power for each user, and is superimposed after being sent to time domain.Thus, the signal of multiple users is transmitted simultaneously in the same frequency domain in the power domain.In the signal receiving end, signal separation is carried out using serial interference cancellation technology, and then the bit stream signal of each user is demodulated and restored in turn by maximum likelihood estimation.The method improves the proportion of index information in the total information, thereby improving the spectral efficiency and reducing the bit error rate, thereby further improving the system performance.

The invention relates to the technical field of unmanned aerial vehicle communication, in particular to a communication method of a dual-channel unmanned aerial vehicle line-of-sight communication system, which comprises the steps of acquiring communication quality, acquiring an optimal transmission frequency point, acquiring task priority of an unmanned aerial vehicle, transmitting video stream data and executing multipath fading compensation. Calculating a frequency point quality index through a signal-to-noise ratio, a signal rate and an error rate, and dynamically selecting an optimal transmission frequency point; allocating communication resources based on task priorities to ensure that key instructions are transmitted preferentially; a differential geometry theory is innovatively adopted to carry out multipath fading compensation, communication signals are mapped to a Riemannian manifold space, and fading features are extracted and optimized; cooperative compensation of high and low frequency channels is realized, and mutual enhancement is realized through receiving spectrum analysis and training sequence correction; and adaptive QAM modulation is supported, modulation parameters are dynamically adjusted according to manifold curvature, and a star-shaped multi-node communication network is constructed.

The application discloses a communication method and device based on QAM-OFDM, relates to the technical field of ultrasonic communication, and comprises the following steps: using convolution code on an original signal to obtain an initial signal, using QAM modulation technology on the initial signal to convert the initial signal into a modulated signal, and using OFDM modulation technology to convert the modulated signal into an analog signal; using spread spectrum technology on the analog signal, and using a power amplifier and a band-pass filter to process the analog signal; receiving the analog signal processed by a steel rail channel; using an analog-digital converter to convert the received signal, using OFDM demodulation technology to demodulate the converted signal, and using QAM demodulation technology to restore the original signal from the demodulated signal. The application can enhance the anti-interference capability of the signal while maintaining efficient signal transmission.

The application discloses a kind of LDPC decoding method based on bidirectional circulation network, belong to communication technical field, including: the 1024QAM signal after transmission by coherent optical system is collected;Discrete channel quantizer suitable for high-order modulation signal is constructed;All bit information is calculated and the uniformity of bit information is completed;Bidirectional information bottleneck decoder is constructed based on bidirectional circulation structure, the check node design of bidirectional information bottleneck decoder;Variable node design of bidirectional information bottleneck decoder.The method utilizes multivariate parameter to construct information bottleneck framework, for all M-QAM modulation format, only need to construct two LUTs extra, can solve the problem that memory requirement increases with modulation order in IB decoding method.In addition, we use bidirectional circulation network and the symmetry of quantized information to realize the multiplexing of table, give full play to the role of intermediate information, make the relationship between the number of LUT search and node degree in IB decoding algorithm from square magnitude to linear magnitude.

The invention provides a wireless communication link high-fidelity simulation method for a high-dynamic Internet of Vehicles, which comprises the following steps of: performing channel modeling by using a channel simulation platform according to an input network layout, a terminal track, a propagation scene and an antenna mode to generate a time-varying channel coefficient; accurate modeling is carried out on key physical phenomena such as multipath propagation, Doppler frequency shift, path gain and propagation time delay in the Internet of Vehicles, and high-fidelity simulation of channel dynamic change characteristics in a high-mobility scene is realized; a transmitter class object, a receiver class object and a channel class object are constructed based on an object-oriented thought, a plurality of processing modules such as QAM modulation, multi-carrier modulation, pilot frequency design, channel estimation and equalization, frequency offset correction and the like are supported, and good transportability and expansibility are achieved. According to the invention, high-fidelity Internet of Vehicles communication system simulation is realized, a communication transceiver signal processing flow is included, and an efficient fidelity verification platform is provided for design and test of an Internet of Vehicles communication protocol and algorithm.

The invention discloses a calibration method of a power amplifier for high-order QAM (Quadrature Amplitude Modulation) modulation signal input. Calibration data is generated for a power amplifier using an input signal of a low-order or medium-order modulation scheme. When the power amplifier is calibrated, whether an input signal of the power amplifier is a modulation signal in a high-order QAM modulation mode or not is judged. And if not, the switching point of every two adjacent gain modes is kept unchanged by the rate amplifier. And if yes, the power amplifier adjusts the switching point of every two adjacent gain modes downwards. According to the invention, the EVM (Error Vector Magnitude) of the power amplifier near the switching point of the adjacent gain modes is reduced, and meanwhile, the power consumption of the power amplifier is not obviously increased.

The invention discloses an orthogonal time-frequency-space transceiver suitable for a satellite-ground scene, and relates to the technical field of satellite communication, in particular to the orthogonal time-frequency-space transceiver suitable for the satellite-ground scene. The invention aims to solve the problem that the bit error rate is too high. The method comprises the following steps of: 1, enabling transmission data to sequentially pass through a convolutional coding module, an interleaving module, a scrambling module, a QAM (Quadrature Amplitude Modulation) module, an OTFS (Over the Top File System) module and a CP (Content Program) adding module, and inserting DMRS (Demodulation Reference Signal) into output data of the 2, framing a data symbol, an information symbol and a leader sequence; 3, the framed data sequentially pass through a DAC and an antenna to enter a time-frequency double-selection channel, an antenna on the other FPGA receives a signal, then the signal passes through an ADC to reach a frame synchronization module, output data are sequentially input into CFO frequency offset estimation and correction, symbol synchronization, CP removal, FFT, channel estimation and equalization, inverse two-dimensional Fourier transform, information symbol solution, QAM demodulation, descrambling, de-interleaving and de-convolution coding modules, and then the output data are sent to a frame synchronization module. And the received 01 sequence is obtained.

The application discloses a device for realizing unidirectional multicast function based on G.hn technology, which comprises a G.hn pusher placed in a front-end machine room, a plurality of G.hn receivers placed in a home as user terminals, coaxial cable connections between the G.hn receivers and the G.hn pusher, each G.hn receiver being capable of joining a multicast group with the G.hn pusher as a multicast source, the G.hn pusher sending multicast data to the multicast group for each G.hn receiver in the multicast group to receive, and the multicast data being cable television service data. All G.hn receivers under the coaxial cable can receive, and the number of the G.hn receivers is unlimited. The application breaks the limitation of traditional technology, redefines the G.hn pusher end and the receiver end, adopts OFDM modulation mode to achieve 4096 QAM modulation, realizes transmission of 8K ultra-high-definition video and VR high-quality service, and provides strong technical support for digital transformation of the cable television industry and future network reconstruction.

The present application relates to an adaptive symbol reconstruction method and system for HPLC channel transient interference, first, the received signal in the HPLC channel is acquired and the transient interference feature is extracted, then the manifold dimension is determined according to the QAM modulation order, the tangent space base vector is generated by calculating the partial derivative of the received sample in each dimension, the metric tensor parameter matrix is calculated based on the inner product of the base vector, the interference mapping relationship is established, then the manifold perception generator of the multi-layer LSTM network and the manifold preserving discriminator of the convolutional neural network are constructed, the discriminator and the generator are alternately trained to realize the antagonistic balance, finally, the received signal is reconstructed into the original symbol based on the trained generator, the present application can effectively resist the arc noise interference with the amplitude of 3 times the signal strength.

The application provides a pre-equalization-based ultra-high-order QAM modulation transmission system and method, which comprises a transmitting end algorithm module, a data transmitting module, a data receiving module and a receiving end algorithm module.The transmitting end algorithm module comprises a pre-equalization processing layer, which processes a to-be-sent data matrix based on a weight matrix; the weight matrix is updated based on the number of 0 taps in the weight matrix after processing the to-be-sent data matrix each time; the data transmitting module comprises an arbitrary wave generator and an IQ modulator, and outputs data through the arbitrary wave generator and the IQ modulator; the data receiving module comprises a coherent receiver and an oscilloscope, the coherent receiver is connected with the IQ modulator through a transmission optical fiber, and incoming data is sequentially processed through the coherent receiver and the oscilloscope; the receiving end algorithm module comprises a decoding layer, receives data transmitted by the oscilloscope, and obtains a received data matrix through the decoding layer.

The invention relates to the technical field of microwave communication, and discloses a microwave communication automatic optimization modulation method based on deep learning, which comprises the following steps of: firstly, transmitting a signal to receiving end equipment by a microwave equipment transmitting end, taking microwave data received by a receiving end as input data, performing initial QAM (Quadrature Amplitude Modulation) grading on the input historical operation data, and then performing data processing on the input historical operation data; the input historical operation data specifically comprises time sequence information of maintenance time, success records and change times; performing data processing and calculation, specifically including classification feature coding, time sequence feature extraction and feature splicing; performing initial probability distribution prediction on the data features; carrying out QAM level selection and feedback updating; and taking the updated historical data and the new operation state as input, repeating the processes of feature engineering, probability prediction, probability adjustment and grade selection, and realizing dynamic adaptive optimization of the QAM modulation grade. According to the method, intelligent switching of modulation levels is realized by automatically and dynamically adjusting the selection probability of a QAM (Quadrature Amplitude Modulation) mode.

The invention relates to an adaptive symbol reconstruction method and system for HPLC channel transient interference, and the method comprises the steps: firstly obtaining a receiving signal in an HPLC channel, extracting transient interference features, then determining manifold dimensions according to a QAM modulation order, generating tangent space basis vectors through calculating the partial derivatives of a receiving sample in each dimension, and carrying out the adaptive symbol reconstruction of the transient interference features. A measurement tensor parameter matrix is obtained based on base vector inner product calculation, an interference mapping relation is established, then a manifold perception generator of a multilayer LSTM network and a manifold maintenance discriminator of a convolutional neural network are constructed, and adversarial balance is realized by alternately training the discriminator and the generator. And finally, reconstructing the received signal into an original symbol based on the trained generator. The method can effectively resist arc noise interference of which the amplitude reaches three times of the signal strength.

The present invention discloses a low-cost terahertz high-order QAM signal direct modulation transmitter and method. In the final stage of the transmitter, a frequency tripler is used to shift the spectrum of two QPSK modulated signals to the terahertz band. The two QPSK (quadrature phase-shift keying) signals are then vector-synthesized to achieve 16-QAM modulation. The use of the frequency tripler eliminates the need for the power amplifier to operate in the terahertz band, thereby lowering the transistor cutoff frequency requirement and processing costs. Furthermore, because the power amplifier operates at a lower frequency, it offers higher efficiency. Furthermore, the high-order QAM modulation is performed directly in the RF domain, significantly reducing the power consumption of the DAC.

The application discloses a kind of SP-2048-QAM modulation methods based on stage truncation shaping, specifically: pre-processing is carried out to signal at transmitting end, from the angle of gradually intercepting signal point, pseudo-random bit sequence is shaped by stage truncation, to realize the step-by-step adjustment of signal point modulus and distribution;Subsequently, shaping is combined with four-dimensional modulation, forming a series of intermediate modulation formats;At receiving end, optical signal is detected after being amplified again, the analog signal detected is converted into digital signal by analog-digital converter, and finally corresponding signal equalization, compensation, demapping decision operation is carried out by digital processing algorithm module, and the original data is recovered.The application improves the transmission performance of system, reduces the bit error rate, enhances the adaptive ability of system, so that it can be adjusted signal entropy value flexibly according to the changing channel condition and noise environment, to ensure the stability and reliability of communication.

The application discloses a high-order QAM massive MIMO signal detection method based on a nested variational chain, and comprises the following steps: receiving a signal to be detected; and performing signal detection on the signal to be detected by using a GTA-EC algorithm to obtain a signal detection result; wherein the GTA-EC algorithm is an improved EP algorithm, in which the GTA algorithm and the EP algorithm are fused based on a nested variational chain to obtain an approximate distribution of a maximum a posteriori probability based on the fused KL divergence; and the maximum a posteriori probability is a probability of obtaining an original estimated signal under the condition that the received signal and the channel gain are known. The application can achieve a low bit error rate and low computational complexity under the conditions of a large number of transceiving antennas and high-order QAM modulation.

The present application relates to the field of shortwave communication technology. To address the issues of low combining gain and limited anti-fading performance resulting from direct hard combining in traditional DRM reception combining methods, which fail to consider the impact of channel quality and signal-to-noise ratio, a reliable shortwave DRM reception method, system, computer-readable storage medium, and electronic device based on time-frequency retransmission are disclosed. The method comprises obtaining the QAM modulation order of each signal copy based on quick access channel information; obtaining the signal-to-noise ratio of each signal copy using a channel estimation algorithm; if the QAM modulation order of each signal copy is the same, weighted combining of each signal copy based on the signal-to-noise ratio on a QAM constellation diagram; and if the QAM modulation order of each signal copy is different, weighted combining of each signal copy based on the signal-to-noise ratio on a bit stream to obtain an enhanced DRM information bit stream. This method can increase combining gain and improve the anti-fading performance of the receiving end.