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82 results about "Circular convolution" patented technology

The circular convolution, also known as cyclic convolution, of two aperiodic functions (i.e. Schwartz functions) occurs when one of them is convolved in the normal way with a periodic summation of the other function. That situation arises in the context of the circular convolution theorem. The identical operation can also be expressed in terms of the periodic summations of both functions, if the infinite integration interval is reduced to just one period. That situation arises in the context of the discrete-time Fourier transform (DTFT) and is also called periodic convolution. In particular, the DTFT of the product of two discrete sequences is the periodic convolution of the DTFTs of the individual sequences.

Primary synchronization signal detection method in LTE system

The primary synchronization signal detection method in an LTE system. The method comprises the following steps: converting cross-correlation process to linear convolution, converting the linear convolution into circular convolution in a zero filling mode, and performing Fourier transform FFT operation to obtain a primary synchronization signal PSS sequence dmf(n) in a local frequency domain; performing the Fourier transform FFT operation on a received signal sequence, and performing point-to-point multiplication on the received signal sequence and the local primary synchronization signal PSS sequence to obtain a cross-correlation power sequence, judging whether the primary synchronization signal PSS is successfully retrieved by judging the peak to average ratio of the cross-correlation power sequence, and if so, calculating a PSS signal position according to the peak position, and calculating a call intra-group identifier; and otherwise, indicating that the retrieval is failed. The primary synchronization signal detection method has the beneficial effects of reducing the complexity of the cross-correlation operation while keeping the wide adaptability of the cross-correlation operation in PSS synchronization, improving the operation accuracy while reducing the single-step operation data size and improving the operation efficiency and accuracy.
Owner:重庆华沐网络科技有限公司

Method and device for decoding iterated internal code and evaluating channel for orthogonal frequency division multiplexing system

ActiveCN101605120ACircular Convolution AccurateCircular convolution is accurateMulti-frequency code systemsOrthogonal multiplexTime domainCoding decoding
The invention discloses a method and a device for decoding an iterated internal code and evaluating a channel for an orthogonal frequency division multiplexing system. The iterating method comprises the following steps: at a transmitting end, carrying out internal code encoding and intraframe interleaving by a code with a long short code; at a receiving end, calculating circular convolution of an OFDM time domain data block and an evaluation value of channel time domain impulse response based on an initial evaluation value of the channel time domain impulse response; completing constellation de-mapping according to the channel evaluation and the result of circular convolution to acquire bit soft information; carrying out intraframe de-interleaving and internal code decoding on the bit soft information to acquire decoded bit soft information, carrying out intraframe interleaving on the decoded bit soft information, and remapping the constellation; and updating the evaluation value of the channel time domain impulse response according to the remapped result, and carrying out channel evaluation post-treatment. The method and the device can improve channel evaluation precision, and reduce system error rate, thereby improving system performance, in particular mobile performance, and ensuring complexity and controllable time delay of the system.
Owner:TSINGHUA UNIV

Low-complexity peak-to-average ratio (PAPR) inhibition method of FRFT-OFDM (fractional Fourier transform-orthogonal frequency division multiplexing) system

The invention relates to a low-complexity peak-to-average ratio (PAPR) inhibition method of an FRFT-OFDM (fractional Fourier transform-orthogonal frequency division multiplexing) system, belongs to the technical field of broadband wireless digital communication, and can be used for reducing the PAPR of the FRFT-OFDM system. The method is based on the Fractional order random phase sequence and the Fractional order circular convolution theorem, and the operation complexity is effectively reduced. The method provided by the invention has the advantages that the system realization is simple, and the calculation complexity is low. According to the method, the reliability of the system is maintained, meanwhile, the PAPR of the system can be effectively reduced, and when the alternative signal numbers are identical, the method has the same PAPR inhibition performance as an SLM (selection mapping) method and has the better PAPR inhibition performance than a PTS (partial transmission sequence) method. In addition, compared with that of the SLM method and the PAPR method, the calculation complexity of the low-complexity PAPR inhibition method is greatly reduced.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

Offshore oil-gas platform detection method based on structural recurrent neural network

The invention discloses an offshore oil-gas platform detection method based on a structural recurrent neural network. The method comprises: according to serialization structure characteristics of a space-time image, a structural recurrent neural network model of a seaborne target is established; parameter optimization adjustment is carried out on the established structural recurrent neural networkmodel and then a high-order space-time characteristic model of the seaborne target is established; on the basis of the high-order space-time characteristic model of the seaborne target, a high-orderspace-time characteristic of the seaborne target is obtained; a bi-directional circular convolution layer is constructed based on the high-order space-time characteristic of the seaborne target and abi-directional circular convolutional neural network with fusion of front and rear time phase features is established; and on the basis of parallel optimization adjustment of the bi-directional circular convolution layer, accurate detection of the seaborne moving target under the single time phase is realized. With the deep learning, the capability of obtaining the target feature is enhanced; andwith full utilization of the time-space features of the target, the target in the complex background interference can be detected. Moreover, the universality of the algorithm is enhanced.
Owner:中国科学院电子学研究所苏州研究院

A channel estimation method for transmit diversity system

The invention discloses a signal channel estimation method of a transmission diversity system and belongs to the technical field of digital information transmission. The method comprises the following steps: a space time code designed according to the matrix orthogonality is taken as a diversity training sequence; a sender fills the diversity training sequence in a data frame and sends the data frame out; a receiver extracts the training sequence filled in the data frame and the linear convolutions of channel impulse response from the corresponding sender to the receiver; the sum of the linear convolutions is reconstructed for acquiring a circular convolution; the frequency domain form of the circular convolution is computed; the frequency domain estimation of the channel impulse response is computed according to the frequency domain form; the channel estimation from the sender to the receiver is computed according to the frequency domain estimation of the channel impulse response. The invention uses the designed space time code as the diversity training sequences, and selects the diversity training sequences with constant modulus in the frequency domains or the sum of frequency domains, thus effectively eliminating interference among the diversity training sequences and simplifying the channel estimation of the transmission diversity system.
Owner:TSINGHUA UNIV

Circular convolution hexagonal multicarrier transmission method

The invention provides a circular convolution hexagonal multicarrier transmission method. The method comprises the following steps: determining the number of sub symbols contained in a sent data block; determining the number of to-be-sent data symbols according to the number of the sub symbols and the number of subcarriers; carrying out shift and zero fill on each to-be-sent data symbol according to the position of a belonging sub symbol on the time to obtain a corresponding sending vector; separately carrying out circular convolution operation on each sending vector and a Gauss pulse shaping function, and carrying out frequency modulation on a circular convolution result according to the sub symbols and the subcarriers belonging to the sending vector to obtain a pulse signal carrying the data symbol information; accumulating the pulse signals to obtain a multicarrier signal; and adding a cyclic prefix for the multicarrier signal according to the maximum delay extension of a channel to form a to-be-send baseband signal. The circular convolution hexagonal multicarrier transmission method provided by the embodiment of the invention has very strong double-selection channel resistance, realizes higher spectrum effectiveness of the to-be-send signal, and meanwhile reduces the peak-to-average power ratio.
Owner:DALIAN MARITIME UNIVERSITY

Deep learning super-resolution method based on enhanced upsampling and discrimination fusion mechanism

The invention provides a deep learning super-resolution method based on an enhanced upsampling and discrimination fusion mechanism, which comprises the following steps of: directly extracting original features of a low-resolution input image by using a single layer based on a deep learning convolutional layer in a residual error branch; using 6 cascaded multi-layer feature fusion-based circular convolution units to extract deep features, and enabling the deep features output by each circular convolution unit to be subjected to up-sampling through 6 deconvolution layers; fusing the up-sampled high-resolution features by applying a feature fusion mode with a discrimination mechanism, and performing dimensionality reduction on the up-sampled features by using a single-layer convolutional layer to obtain a residual error of the high-resolution image; carrying out up-sampling on the low-resolution image by using a bicubic interpolation method in a mapping branch; and adding the mapping and the residual of the high-resolution image pixel by pixel to obtain a final high-resolution image. According to the invention, an up-sampling opportunity is provided for low-resolution characteristics of each stage, and higher reconstruction accuracy is obtained.
Owner:GUANGZHOU TUWEI NETWORK TECH

Correlated peak position information-based time synchronization method for underwater acoustic spread spectrum communication

ActiveCN103701489ASolve problems with high computing power requirementsReduce computing power for issues with higher requirementsTransmissionPeak valueComputer science
The invention discloses a correlated peak position information-based time synchronization method for underwater acoustic spread spectrum communication. The method comprises the following steps: 1, initializing parameters of a receiving terminal; 2, acquiring a signal by using the receiving terminal; 3, performing correlation operation on a second processed signal block variable and a local synchronization reference signal; 4, calculating the peak position of a correlation operation result of the second processed signal block variable and the local synchronization reference signal; 5, judging whether a difference value between pos_1 and pos_2 is less than a certain permissible deviation range or not; 6, extracting a section of the signal s1(k) from the first processed signal block variable; 7, performing circular convolution calculation on the s1(k) and an inverted sequence sflip1r(k) of a local demodulation reference signal; 8, judging whether the deviation of the peak position from the starting or ending position of the signal is within a certain permissible deviation range or not. According to the method, the addition of a signal head is avoided, the easiness in networking is ensured, the requirements on the calculation capability of a platform are low, the method is convenient to operate, and the pseudo triggering or triggering omission rate is reduced.
Owner:中国船舶重工集团公司第七二六研究所
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