338 results about "Constellation diagram" patented technology

The invention discloses a three-dimensional signal secure transmission method and device based on index modulation. The method comprises the following steps: generating four-dimensional chaotic sequences X, Y, Z and U from a key initial value through a chaotic model; performing XOR operation on the original data by using an encrypted sequence generated by X and U in the four-dimensional chaotic sequence to obtain encrypted data; performing binary conversion on the key initial value to obtain a binary key initial value consisting of N four bits; dividing the encrypted data into N groups, each group having 15 subcarriers, determining a to-be-inserted silent position of each group of subcarriers according to a binary key initial value, performing three-dimensional mapping after the silent subcarriers are inserted, and setting the silent subcarriers at an original point position to obtain a three-dimensional constellation diagram; performing constellation masking on the three-dimensional constellation diagram by using Y and Z in the four-dimensional chaos sequence; carrying out IFFT (Inverse Fast Fourier Transform) on the three-dimensional constellation diagram after constellation masking, adding a suffix, and carrying out parallel-serial conversion to obtain transmission data; and transmitting the transmission data to a receiving end through an optical fiber channel.

The invention discloses a signal transmission method and device based on joint index modulation, and belongs to the technical field of communication. Through the joint index modulation rule, accompanying transmission of the secret key of the multi-layer encrypted chaotic system is achieved, the rule has a certain constellation forming effect on a constellation diagram, and by optimizing the dual-mode index rule and the subcarrier index rule, optimized distribution of internal constellation points is achieved, and the transmission performance of signals is improved; in addition, only a legal receiving end can extract a correct key through a joint index rule for decryption and demodulation, and an illegal receiving end cannot realize correct demodulation due to the effect of multi-layer encryption and the loss of the key, so that high-safety and high-performance transmission of the key and the signal is ensured.

The invention discloses a coding method and device based on power domain chaotic distribution matching. The method comprises the following steps: acquiring a key initial value and to-be-sent original data; performing chaotic encryption on the key initial value through a Chua's chaotic system to generate a chaotic sequence; carrying out system conversion on the key initial value, and carrying out mapping processing according to a rule to obtain a key stream formed by a QPSK constellation diagram; performing encryption and serial-to-parallel conversion on original data in a binary form by using the chaos sequence, and then performing quadrature phase shift keying (QPSK) mapping to obtain an information stream formed by uniformly distributed QPSK constellation diagrams; respectively carrying out power distribution on the key stream and the information stream, and carrying out constellation diagram superposition on the key stream and the information stream after power distribution to form an encrypted stream of a non-uniformly distributed 16 QAM constellation diagram; and performing translation rotation on each region of the partitioned constellation diagram of the encrypted stream according to a rule, and finally realizing probabilistic shaping to obtain the PS-16QAM constellation diagram encrypted stream. The method can improve the quality of signal transmission.

The invention discloses a secure magnetic communication method and system based on a key index. The method comprises the following steps: generating four columns of chaotic sequences according to a set key initial value by using a four-dimensional hyper-chaotic model; inserting the two columns of chaos sequences into original transmission data, performing convolution encryption to obtain an encrypted bit stream, performing serial-parallel conversion on the encrypted bit stream to obtain a data matrix H, and performing subcarrier scrambling and symbol scrambling on the data matrix H in sequence according to the other two columns of chaos sequences to obtain a data matrix P; taking the key matrix as an index, performing QPSK mapping on elements in the data matrix P through a constellation codebook to obtain constellation points, and forming a constellation diagram by the constellation points; transmitting the constellation diagram to a receiver through a transmitter; in response to the constellation diagram received by the receiver, decrypting the constellation diagram to obtain original transmission data; according to the invention, the problem that the magnetic induction signal is easy to steal is solved, and the security of the communication system is improved.

The invention provides a code modulation method and device, electronic equipment, a storage medium and a program product. The method comprises the following steps: probability constellation shaping coding is carried out on a payload bit data stream to be sent to obtain a bit data stream after shaping coding, and the bit data stream after shaping coding comprises non-equal-probability amplitude bits corresponding to orthogonal amplitude modulation constellation points and a part of equal-probability symbol bits; the bit data stream after shaping coding is recombined and adapted to be in a frame format corresponding to error correction coding, forward error correction coding is carried out, an error correction code bit data stream is obtained, and the error correction code bit data stream comprises non-equal-probability amplitude bits corresponding to orthogonal amplitude modulation constellation points and equal-probability symbol bits; and recombining and adapting the error correction code bit data stream into a frame format corresponding to quadrature amplitude modulation, and mapping into a plurality of modulation constellation points according to a quadrature amplitude modulation constellation diagram. The signal-to-noise ratio is improved, and the communication performance and the transmission stability are improved.

The invention discloses an optical fiber terahertz communication system optimization method based on artificial intelligence, and belongs to the technical field of communication. According to the method, four-dimensional constellation shaping is constructed by utilizing additional dimensions provided by two independent sidebands, and an end-to-end optimization framework is divided into a training stage and a deployment stage; in the training stage, firstly, an equalizer based on a pruning neural network and an equalized channel model based on a mixed density network are trained in sequence through receiving and transmitting of a random training sequence; then connecting a constellation shaper at a transmitting end with a demapper at a receiving end through an equalized channel model with fixed parameters, thereby considering full-link residual distortion and noise after equalization, and carrying out back propagation gradient to learn a globally optimal four-dimensional joint geometric probability constellation diagram to further approach the Shannon limit; and in the deployment stage, transmission of the bit stream is realized through coordination of the four-dimensional geometric shaping constellation table and the probability distribution obtained in the training stage and an equalizer at the receiving end and a demapper.

The embodiment of the invention provides a power control method and a communication device. The method comprises the following steps: generating a data signal subjected to amplitude limiting processing; determining a power offset, the power offset being used for determining a transmission power ratio between the data signal and a first channel, the first channel being a channel bearing the data signal; and determining the target sending power of the first channel according to the power offset. Thus, the sending power ratio between the data signal and the first channel is determined according to the power offset, and then the target sending power of the first channel can be determined, so that the offset, generated on a constellation diagram, of a modulation symbol borne by the data signal due to amplitude limiting processing of the data signal can be compensated; therefore, the misjudgment probability when the receiving end demodulates the data signal can be reduced.

A small sample modulation identification method based on combination of multi-domain contrast learning and reinforcement learning comprises the following steps: 1) obtaining a data set, dividing the data set into a base set, a support set and a verification set, converting the data set into a time domain, a frequency domain and a constellation diagram form, and obtaining a corresponding encoder and a common projection head; 2) inputting the base set data into an encoder for feature extraction, inputting the obtained features and accuracy as a state and an award into a decision body for reinforcement learning training to obtain a data enhancement action, inputting the original data and the enhancement data into the encoder and a projection head, and performing comparative learning training in a high-dimensional space to obtain a data enhancement action; the reinforcement learning training is repeated until the rewards are not increased any more; 3) loading and freezing encoder parameters, and training an attention module and a linear classifier by using a support set; and 4) loading and freezing all module parameters, and verifying the performance by using the verification set. According to the method, the signal model can have good performance in a small sample scene.

The invention discloses a simple receiving multiple access method based on joint allocation of symbols and bit streams. The method comprises the following steps: firstly, allocating the symbol streams and the bit streams of all users by a transmitter based on a layered orthogonal amplitude modulation constellation diagram; different interference management schemes are adopted for inter-user interference in different beams and inter-user interference in the same beam, so that the influence of the inter-user interference on the system performance is suppressed; and performing channel equalization processing on signals received by each user receiver, calculating the log-likelihood ratio of each bit stream allocated to each user by each user according to a bit stream allocation result, and sending a calculation result to a channel decoder to obtain original bit data. According to the method, each user symbol and bit stream allocation scheme and constellation diagram design are jointly optimized, and efficient user access in a large-scale access scene can be realized under the condition of meeting the signal processing complexity constraint condition of a receiver.

The invention discloses an electromagnetic target recognition method based on interpretable multi-task learning, a storage medium and equipment, and the method comprises the steps: firstly constructing a multi-task learning network facing modulation recognition and individual recognition, inputting an original signal, setting a hyper-parameter, and carrying out the training of the multi-task learning network; constructing a generator for outputting a disturbance signal, segmenting an original signal and generating an original mask, generating a disturbance mask through an inversion element, and further generating the disturbance signal; inputting the disturbance signals into the trained multi-task learning network to obtain probability distribution of classification results under different tasks; taking a prediction probability of a multi-task model to a disturbance signal as a supervision label, training a local linear model on an original mask and a disturbance mask, and taking a model weight Wg as a contribution degree of each subsequence to explanation through optimization; and performing normalization processing on the Wg, mapping the weight back to the original signal length, and visually marking a time-frequency domain signal region which plays a key role in model decision based on a constellation diagram.

The invention provides a coding modulation method and a related device, and the method comprises the steps: carrying out the coding of N input bit sequences through employing code rates corresponding to the N input bit sequences, and obtaining N coded bit sequences corresponding to the N input bit sequences; the length of each input bit sequence is determined according to at least one of a code rate, a modulation order or the number of resource elements (RE) used for data transmission corresponding to the input bit sequence; the N coded bit sequences are mapped to the same constellation diagram, the constellation diagram comprises M constellation points, each constellation point comprises N segmented bits, and the N segmented bits correspond to the N coded bit sequences respectively. According to the process, the transmission efficiency is guaranteed, the coding complexity of the sending end is reduced, in addition, the protocol modification degree is also reduced, and the coding implementation cost is further reduced.

The invention discloses a three-dimensional 16QAM constellation diagram based on geometric shaping and a digital communication method, and relates to the field of communication, in a three-dimensional space, 16 constellation points are distributed on the surface of a three-dimensional sphere with the radius of 2.5, and 8 constellation points are distributed on each of the upper hemispherical surface and the lower hemispherical surface; a regular pentagon parallel to the XOY plane is formed by five constellation points in the upper hemispherical surface, the center of the regular pentagon coincides with the projection of the sphere center on the XOY plane, and one edge of the regular pentagon is parallel to the XOZ plane; the other three constellation points form an equilateral triangle parallel to the XOY plane, the center of the equilateral triangle coincides with the projection of the sphere center on the XOY plane, and the vertical bisector of one edge of the equilateral triangle is parallel to the YOZ plane; and rotating the eight constellation points of the upper semi-spherical surface by 180 degrees along the center of the sphere in the direction parallel to the YOZ plane to obtain the distribution of the constellation points of the lower semi-spherical surface. According to the method, the channel noise tolerance and the overall transmission performance of the system are improved, the bit error rate is reduced, and the method has an important application prospect in a high-tolerance and high-performance transmission system.

The invention relates to an APSK (Amplitude Phase Shift Keying) demodulation method based on K-Means clustering, and the method comprises the steps that a transmitting end transmits an APSK modulation signal, and a constellation diagram corresponding to the signal is known; a receiving end receives the signal, estimates and eliminates a static direct current component of the received signal, and obtains a processed signal; calculating each constellation point of the processed signal according to a constellation diagram corresponding to the sent APSK modulation signal and the processed signal; according to the constellation points obtained through calculation, clustering is carried out through a K-Means clustering algorithm, and residual direct current components of the processed signals are eliminated; and taking the clustering convergence center after clustering as a constellation point theoretical value of an MAP algorithm, performing soft demodulation by adopting the MAP algorithm, and solving to obtain accurate log-likelihood ratio information. According to the invention, the direct current component in the received signal can be eliminated, and the bit error rate of the APSK demodulation signal at the receiving end is obviously reduced.

The embodiment of the invention provides a communication method and device, relates to the field of communication, and solves the problem that the communication performance of a wireless optical communication system is affected by signal related noise in the wireless optical communication system. The specific scheme is as follows: a network device acquires a current channel state between the network device and a terminal device; the network equipment sends a first constellation diagram to the terminal equipment, the positions of constellation points in the first constellation diagram are determined according to the current channel state, the position distribution of the constellation points is non-uniform, the positions of the constellation points are used for indicating amplitudes of symbols mapped to the constellation points, and the symbols are symbols used for communication between the network equipment and the terminal equipment. The embodiment of the invention is used for the communication process between the network equipment and the terminal equipment.

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 hollow-core optical fiber communication method and system for reducing complexity, and the method comprises the steps: obtaining original bit data, and mapping the original bit data to an initial constellation diagram through a quadrature amplitude modulation mapping algorithm; rotating the initial constellation diagram according to a preset rotation angle to obtain a first constellation optimization diagram, adjusting the first constellation optimization diagram by using a sparrow search algorithm to obtain a second constellation optimization diagram, converting the second constellation optimization diagram into a transmission signal, and transmitting the transmission signal to the receiving end through a hollow-core optical fiber; performing data preprocessing on the received transmission signal to obtain a de-noised signal, performing phase recovery on the de-noised signal based on a quadratic algorithm to obtain a second constellation optimization graph, and performing de-mapping on the second constellation optimization graph to re-convert the second constellation optimization graph into original bit data; according to the invention, the complexity of digital signal processing is reduced, and the accuracy and efficiency of phase recovery are obviously improved, so that the performance of a coherent optical communication system based on the hollow-core optical fiber is comprehensively improved.

The invention relates to a task-oriented semantic communication-oriented adaptive source channel coding system, which belongs to the field of wireless communication, and comprises a sending end for extracting a semantic feature map for evaluation from input data through a feature extractor initialized based on a pre-training large model, executing nested quantization and arithmetic coding based on a calculated importance score, and sending the semantic feature map to a task-oriented semantic communication-oriented adaptive source channel coding system; generating a scalable semantic bit stream with importance levels; the physical layer is used for carrying out reordering and grouping according to importance levels of bit streams, a channel encoder is combined with an interleaver to realize unequal error protection of semantic matching, and encoded bits are mapped to sign bits with different fault-tolerant capabilities in a constellation diagram through division modulation; and a receiving end: recovering the semantic feature map through arithmetic decoding and nested inverse quantization. According to the invention, on the premise of keeping compatibility with a digital communication protocol stack, through distortion-driven joint rate self-adaption, the transmission effectiveness for machine tasks and human vision is obviously improved under a limited bandwidth.

The invention discloses an encryption communication method and system based on biological genetic coding chaos driving, and the method comprises the steps: receiving an original bit stream and an initial secret key, and generating a chaos sequence group according to the initial secret key through two hyperchaos models; performing DNA coding encryption on the original bit stream by using the chaos sequence to obtain a gene transmission sequence, and performing DNA decoding on the gene transmission sequence to obtain a transmission bit stream; performing constellation mapping on the transmission bit stream to obtain a constellation diagram, and performing subcarrier scrambling, symbol scrambling and constellation rotation on the constellation diagram according to the chaos sequence; performing OCDM modulation on the constellation diagram through an inverse discrete Fresnel transformation matrix to obtain a transmission signal; hiding the initial key in a frame header of a transmission signal, and sending the transmission signal to a receiver through a transmitter; according to the invention, multi-layer encryption of the OCDM signal and dynamic secret key follow-up transmission are realized.

The present invention discloses a signal modulation recognition method based on feature fusion, comprising: obtaining a data set of modulated signal samples; preprocessing the modulated signal samples, including extracting a spectrum and constellation diagram of the modulated signal samples; normalizing the spectrum and constellation diagram, and concatenating the normalized spectrum and constellation diagrams to obtain a corresponding fused feature diagram, and dividing the fused feature diagram into a training set and a test set; establishing a deep neural network model, the deep neural network model including a CNN network, an LSTM network, an attention mechanism module, and a classifier connected in sequence; inputting the fused feature diagram in the training set into the deep neural network model for training to obtain a trained deep neural network model; inputting the fused feature diagram of the actual received signal into the trained deep neural network model for recognition to obtain a modulation recognition result. This method enhances feature diversity and has high recognition accuracy and generalization capability.

The invention discloses a hollow-core optical fiber Kerr effect nonlinear coefficient characterization method, device and equipment and a storage medium, and relates to the technical field of optical communication, and the method comprises the steps: receiving a high-order modulation signal transmitted by a to-be-tested hollow-core optical fiber in a transmitting end, and carrying out the demodulation of the high-order modulation signal, and obtaining a high-order demodulation signal; mapping the high-order demodulation signal into a constellation diagram, and determining the nonlinear phase shift of the high-order demodulation signal in the constellation diagram; based on the nonlinear phase shift of the high-order demodulation signal in the constellation diagram and a pre-constructed Kerr effect nonlinear mathematical model, determining a Kerr effect nonlinear refractive index coefficient of the to-be-tested hollow-core optical fiber; and based on the Kerr effect nonlinear refractive index coefficient of the to-be-tested hollow-core optical fiber, optimizing the communication performance of the to-be-tested hollow-core optical fiber. Through the mode, the mapping points in the demodulated signal constellation diagram are analyzed to determine the nonlinear phase shift, so that the nonlinear refractive index coefficient of the Kerr effect is accurately calculated by utilizing the nonlinear mathematical model and the nonlinear phase shift.

The invention discloses an orthogonal frequency division multiplexing transmission method and system based on probability shaping. The method comprises the following steps: grouping constellation points according to transmitting power to obtain a symbol mode; constructing a mapping relation between index bits and modulation strategies according to a set mapping probability to obtain the mode distribution table; the method comprises the following steps: dividing an input original bit into an index bit sequence and a data bit sequence, querying a preset mode allocation table according to the index bit sequence to obtain a modulation strategy, and performing constellation mapping on the data bit according to the modulation strategy to generate a constellation point; mapping the constellation points to a subcarrier to generate an orthogonal frequency division multiplexing symbol block; converting the orthogonal frequency division multiplexing symbol block into a transmission signal; in response to the received transmission signal, the transmission signal is recovered to obtain the original bit, probability shaping is performed on the constellation points in the constellation diagram, so that a high-power symbol is allocated with fewer subcarriers, and the bit error rate in the communication transmission process is improved.

The invention provides a high-dimensional index modulation OTFS implementation method and system based on wavelet transform, and relates to the field of wireless communication, and the method comprises the steps: completing single-mode index modulation mapping or dual-mode index modulation mapping through employing a high-dimensional signal constellation diagram, and constructing a time delay-Doppler domain OTFS signal; a Mallat wavelet transform technology is adopted to complete modulation of the time delay-Doppler domain OTFS signal, and a two-dimensional time domain OTFS signal is obtained; and vectorizing the two-dimensional time-domain OTFS signal, adding a cyclic prefix, and sending the vectorized two-dimensional time-domain OTFS signal into a time-varying channel for transmission, thereby realizing a high-dimensional OTFS system based on wavelet transform. According to the method, the traditional Fourier transform is replaced by the wavelet transform, so that the reliability of the system is improved, and the complexity of the system is reduced. Index modulation is introduced to improve the spectrum efficiency, future communication requirements are better met, and the technical problem that the reliability of the system is improved by a high-dimensional constellation diagram but the spectrum efficiency is lost is solved.

The present invention proposes a method for data enhancement and individual identification of small-sample radiation sources based on equipotential constellation diagrams, comprising the following steps: preprocessing the collected I / Q signals emitted by the radiation source, and mapping the one-dimensional I / Q signal sequence data onto a two-dimensional equipotential constellation diagram image. An improved generative adversarial network is used to perform data enhancement on the two-dimensional equipotential constellation diagram of the I / Q signal sample, and a structural similarity measurement method is used to screen the generated equipotential constellation diagram to optimize the quality of the generated samples. A residual neural network recognition model is constructed, and the generated sample data set is merged with the original data set for model training. Finally, the obtained radiation source recognition model identifies the radiation source device in the small-sample scenario. By comprehensively applying technologies such as mapping the I / Q signal sequence data to images, data enhancement and screening, the model provides an effective solution for individual identification of radiation sources in small-sample scenarios.

The invention specifically relates to an MIMO signal modulation mode identification method and system in a strong interference environment. The method comprises the following steps: introducing a tensor analysis theory to construct a high-order cumulative tensor model of an MIMO signal in the strong interference environment; designing a least square method in combination with an enhanced linear search algorithm, and performing regular tensor decomposition on the high-order cumulative tensor model to reconstruct an MIMO signal; carrying out constellation diagram mapping on the reconstructed MIMO signal to generate a constellation diagram, and extracting the characteristics of the constellation diagram by using a fractional order wavelet scattering network; constructing a feature collaborative representation classifier based on Grassmann manifold, and obtaining the probability of MIMO signal modulation categories; and constructing an objective function by using the maximum joint probability, converting an optimization problem into a process of searching an optimal linear combination coefficient through weight design, and determining a modulation mode of the MIMO signal. The MIMO signal modulation mode identification method is good in effect, and MIMO signal modulation mode identification in Gaussian noise and strong interference environments can be effectively realized.

The invention discloses a wireless communication transmitter and method based on a transmission-type space-time joint coding metasurface, and belongs to the technical field of high-frequency-band wireless communication. The transmitter comprises a 10 * 10 transmission type intelligent metasurface array, a four-way space-time joint encoder and a control system, 0-degree, 90-degree, 180-degree and 270-degree four-phase compensation of + 1-order harmonic waves is generated by applying four-way control signals with different time delays (0, 0.25 T, 0.5 T and 0.75 T), baseband signal modulation is completed by combining QPSK mapping, and dynamic beam forming is achieved through spatial domain phase gradient compensation. The time delay configuration of the difference 90-degree phase of the four paths of signals enables each column unit of the metasurface to synchronously complete information modulation and beam pointing control under time domain and space domain joint coding. According to the invention,-30-30-degree beam scanning is realized in the 6.6 GHz frequency band, the main lobe gain reaches 17.8 dBi, the orientation error is less than 2 degrees, and the constellation diagram EVM is superior to 8%. The method has the advantages of low loss, high orientation precision and confidentiality, and is suitable for a 6G communication system and a dynamic reconfigurable network.

The invention relates to the technical field of signal identification, in particular to a signal identification method and device, identification equipment and a storage medium. The method comprises the following steps: preprocessing a collected signal to be identified to obtain an oscillogram, a power diagram and an effective bandwidth of the signal to be identified, determining the actual length of each special sequence through the oscillogram and the power diagram, and estimating the length of each OFDM symbol through the actual length of each special sequence; taking the length and the effective bandwidth of each OFDM symbol as basic parameters, performing estimation based on the basic parameters to obtain at least one group of estimation parameters, mapping a to-be-identified signal into a constellation diagram based on each estimation parameter, determining a modulation type corresponding to each constellation diagram, determining a target parameter from each estimation parameter based on the modulation type corresponding to each constellation diagram, and determining a to-be-identified signal according to the target parameter. And determining a complete parameter of the to-be-identified signal based on the target parameter to obtain an identification result. According to the method provided by the invention, the identification efficiency of the unknown OFDM signal can be improved.

The invention provides a communication method and a communication device, which are applied to the technical field of communication. In the technical scheme provided by the invention, the bit sequence is modulated by using the constellation diagram which is linearly combined with the plurality of constellation diagrams to meet the preset relational expression, so that the complex value modulation symbol is obtained. According to the technical scheme of the invention, the transmission requirements of information with different transmission performances can be met.

The invention provides a signal-to-noise ratio estimation method and device suitable for PSK (Phase Shift Keying) modulation. The method comprises the following steps: calculating the average power of an input signal sequence; estimating the average power of the pilot frequency sequence; and calculating a signal-to-noise ratio. According to the method, the influence degree of noise on the distance between the PSK modulation signal and the original point in the constellation diagram is estimated, a traditional method for calculating the signal-to-noise ratio by estimating the deviation degree of the actual signal from the ideal signal due to the influence of noise is replaced, high accuracy can still be kept when the signal is influenced by Doppler frequency deviation and sampling deviation, the method is more suitable for an actual communication system, and compared with the prior art, the method has the advantages of simple operation and low cost. In an actual communication system, signal-to-noise ratio estimation is usually carried out after signal timing synchronization and carrier synchronization processing, however, the signal-to-noise ratio calculation method provided by the invention can be used for estimating the signal-to-noise ratio after synchronization before synchronization according to PSK modulation characteristics, and has certain application advantages in scenes such as switching modulation waveforms according to the signal-to-noise ratio.

The present application provides a communication method and a communication apparatus, applicable to a simultaneous wireless information and power transfer scenario. A constellation diagram for an energy transmission frequency domain resource unit is designed, so that modulation symbols on the energy transmission frequency domain resource unit and a data frequency domain resource unit correspond to different constellation diagrams, that is, the data frequency domain resource unit and the energy transmission frequency domain resource unit are modulated by means of different modulation modes, enabling a receiving end device to correctly identify the position of the energy transmission frequency domain resource unit, thereby demodulating correct data.

The embodiment of the invention discloses a transform domain covert communication method based on an intelligent reflecting surface, and relates to the technical field of safety communication. According to the method, the legal channel and the eavesdropping channel of the multi-participation weight fractional Fourier are reconstructed by optimizing the phase of the intelligent reflecting surface, so that the secrecy rate is maximized. Moreover, by taking a constellation diagram fuzzy error and a rotation error detected by an eavesdropping end as optimization targets, the error between a multi-participation weight score Fourier camouflaged constellation diagram reaching the eavesdropping end and an existing signal constellation diagram in the environment is minimum through alternate optimization of multi-participation weight score Fourier and intelligent reflecting surface control parameters, so that the accuracy of the constellation diagram is improved. Therefore, the camouflage effect is improved. Compared with the condition that the intelligent reflecting surface is not used, the secrecy rate of the communication system can be remarkably improved; and meanwhile, the bit error rate performance of a legal receiving end is improved, and the bit error rate performance of a malicious eavesdropping end is deteriorated. Therefore, the effects that the legal link performance can be guaranteed and the eavesdropping end is interfered are achieved.