31 results about "DFT matrix" patented technology

Provided is a radio communication device which can reduce ISI caused by destruction of an orthogonal DFT matrix even when an SC-FDMA signal is divided into a plurality of clusters and the clusters are respectively mapped to discontinuous frequency bands. The radio communication device includes a DFT unit (110), a division unit (111), and a mapping unit (112). The DFT unit (110) uses the DFT matrix to execute a DFT process on a symbol sequence in a time region to generate a signal (SC-FDMA signal) of the frequency region. The division unit (111) generates a plurality of clusters by dividing the SC-FDMA signal with a partially orthogonal bandwidth corresponding to the vector length of some of the column vectors constituting the DFT matrix used in the DFT unit (110) and orthogonally intersecting at least partially. The mapping unit (112) maps the clusters to discontinuous frequency bands.

The invention discloses a light DFT-S-OFDM secure transmission system based on a digital chaos. The system comprises three encryption steps all together, i.e., insertion of an OFDM synchronous training sequence, DFT matrix signal preprocessing and subcarrier mapping, wherein an OFDM synchronous training sequence and a subcarrier mapping mode are both generated by a chaotic system, DFT matrix element parameters m and n are generated by the chaotic system, by use of initial value sensitivity and pseudo randomness of the digital chaos, encryption processing is performed on DFT-S-OFDM signals, and thus secret transmission is realized. On one hand, since a security system secret key space is huge, the security of high-speed information transmission can be effectively enhanced, and at the same time, since a DFT matrix can substantially reduce a peak average power ratio (PAPR) of OFDM signals, the performance of the transmission system is also improved; and on the other hand, since multiple iteration optimization and multiple discrete Fourier transformation operation are unnecessary in a DFT matrix signal processing system, the whole system has the following advantages: the system architecture is simple, the calculation amount is small, the transceiver cost is low, and transmission of sideband information is unnecessary.

A rate adaptive transmission scheme for MIMO systems, which can transmit a variable number of data symbol streams, provide transmit diversity for each data symbol stream, and fully utilize the total transmit power of the system and the full power of each antenna. In one method, at least one data symbol stream is received for transmission from a plurality of antennas. Each data symbol stream is scaled with a respective weight corresponding to the amount of transmit power allocated to that stream. The scaled data symbol stream(s) are multiplied with a transmit basis matrix to provide a plurality of transmit symbol streams for the plurality of antennas. The transmit basis matrix (e.g., a Walsh-Hadamard matrix or a DFT matrix) is defined such that each data symbol stream is transmitted from all antennas and each transmit symbol stream is transmitted at (or near) the full power for the associated antenna.

The invention relates to a method for recovering signals and frequencies in phase-sensitive OTDR sensing by random monopulse sampling, which is used for signal reconstruction and frequency recovery inphase-sensitive OTDR and comprises the following steps of: (1) determining an observation matrix corresponding to sine signals required in an experiment; (2) determining an observation vector y corresponding to the observation matrix; (3) obtaining a sparse matrix of the signal by using the discrete Fourier transform matrix; (4) carrying out signal reconstruction and frequency recovery on the signal by using an orthogonal matching pursuit algorithm OMP; and (5) transforming the time domain of the signal into the frequency domain through Fourier transform, thereby obtaining the signal and thefrequency. According to the invention, the high-frequency signal can be recovered at a relatively low sampling frequency, so that the sampling and calculating cost of the adopted sensor is greatly reduced.

In an apparatus and method for generating a SC-FDMA signal having a sequence of symbols, a signal is generated by spreading blocks of symbols using a spreading code, then applying an inverse discrete Fourier transform (IDFT) to the symbols, followed by rotating the phase of each symbol, and applying a guard interval in the form of a cyclic prefix (CP), such that the spreading code is selected from sequences having a DFT matrix and Hadamard-Walsh sequence, and whereby the difference between the amounts for rotating the phase of adjacent symbols is constant. The spreading may be changed so as to change the data rate for each transmitter.

A rate adaptive transmission scheme for MIMO systems, which can transmit a variable number of data symbol streams, provide transmit diversity for each data symbol stream, and fully utilize the total transmit power of the system and the full power of each antenna. In one method, at least one data symbol stream is received for transmission from a plurality of antennas. Each data symbol stream is scaled with a respective weight corresponding to the amount of transmit power allocated to that stream. The scaled data symbol stream(s) are multiplied with a transmit basis matrix to provide a plurality of transmit symbol streams for the plurality of antennas. The transmit basis matrix (e.g., a Walsh-Hadamard matrix or a DFT matrix) is defined such that each data symbol stream is transmitted from all antennas and each transmit symbol stream is transmitted at (or near) the full power for the associated antenna.

A method for a user equipment to precode and transmit an uplink signal efficiently in a 2 -antenna system and a method for a base station to receive the transmitted signal efficiently are disclosed. A 2 -antenna codebook includes 4 DFT matrixes and 2 antenna selection matrixes for a rank 1 and one identity matrix for a rank 2 as precoding matrixes. For efficient uplink signal transmission/reception, the present invention provides signal transceiving technology between user equipment and base station using the 2 -antenna codebook.

Techniques are provided that are able to use a substantially smaller number of complex multiplication operations to obtain the same channel estimate than the brute force approach to obtaining the channel estimate. In one approach, an intermediate vector B is first derived (418) based on K subvectors of vector H for channel frequency response estimation and at least two DFT submatrices of DFT matrix W, where K>1. An intermediate matrix A of the DFT matrix is ​​also obtained (420). A least squares channel impulse response estimate is then derived based on intermediate vector B and intermediate matrix A (422). In one implementation, the intermediate vector B is first computed based on the DFT of the matrix HTxL formed by the vector H to provide the matrix GLxL. The inner product between the columns of the basic DFT submatrix W1 and the rows of the matrix GL×L is then computed to obtain the terms of the intermediate vector B.

The invention discloses a direction finding estimation method based on four-order cumulant vectorization DFT. The method comprises the steps that a four-order cumulant matrix is obtained through received signals of a nested matrix and vectorization processing is carried out on the four-order cumulant matrix to obtain a vector z; the z is sorted, redundancy is deleted, and a received signal z1 of acontinuous virtual array element is obtained; a DFT matrix F is constructed, a vector y = Fz1 is calculated, the positions of K maximum peak values of the vector y is obtained, a phase rotation matrix is constructed, an offset phase is obtained through spectral peak search in a small range, and a parameter estimation result is obtained. According to the method, the complexity and the angle estimation performance can be fully balanced, and the limitation that in a traditional sparse array angle estimation method, the angle estimation performance is good but the complexity is high or the calculation complexity is low but the angle estimation performance is low is broken through.

The invention provides a pilot frequency information symbol sending method, a channel estimation method and communication equipment. The method comprises the steps: determining a pilot frequency information symbol corresponding to each antenna on each pilot frequency resource according to a discrete Fourier transform (DFT) matrix and a perception matrix; for each antenna, sending a corresponding pilot frequency information symbol on each pilot frequency resource, wherein the sensing matrix is determined through training of channel information. According to the embodiment of the invention, the problem of channel estimation of a large-scale MIMO communication network is solved.

The invention discloses an RF (Radio Frequency) fingerprint database establishment method. The method comprises following steps of discretizing a to-be-positioned region into N detection points; generating an N-order discrete Fourier transform matrix F relative to the N detection points; extracting M lines from the matrix FH according to a preset sampling quantity M, thus forming an M-line N-column observing matrix B with a minimum correlation coefficient; generating an M-dimensional signal feature vector y->arrow according to signal features obtained by measuring the M detection points corresponding to the line mark numbers of the extracted lines; restoring according to the observing matrix B and the M-dimensional signal feature vector y->arrow, thus obtaining the N-dimensional signal feature vector r->arrow of all N detection points in the to-be-positioned region; and establishing an RF fingerprint database according to the signal feature vector r->arrow, wherein the database is used for search and comparison when RF fingerprints are positioned. The invention also discloses an RF fingerprint database establishment device. The workload for establishing and updating the RF fingerprint database can be saved; and moreover, the reliability and accuracy of the restoration results are ensured.

The invention provides a communication method, device and system. The method comprises the following steps: the terminal equipment determines at least one column vector in a first basis matrix as a space domain basis vector; cSI is sent to a network device, the CSI comprises a spatial-domain basis vector index indication corresponding to the spatial-domain basis vector, the first basis matrix is determined according to at least one of a second basis matrix and a first matrix, the second basis matrix is obtained according to N1-K1 rows of a first DFT matrix, and the first matrix is obtained according to the second matrix and/or a third matrix, each column vector of the second matrix includes one or more sets of phase compensation values, and each column vector of the third matrix includes one or more sets of amplitude compensation values. Based on the scheme, the orthogonal DFT basis matrix is corrected, so that the orthogonal DFT basis matrix is suitable for airspace compression of irregular antenna arrays with array irregularity, amplitude offset phenomenon and phase jump phenomenon, and correct communication between terminal equipment and network equipment is guaranteed.

The invention belongs to the technical field of satellite safety communication, and discloses a wireless communication data-carrying AN auxiliary safety transmission method and application, and the method comprises the steps: disturbing a column vector in an original discrete Fourier transform (DFT) matrix by adopting a chaotic pseudo-random sequence, and changing the inherent period of WFRFT, wherein the columns of the chaotic scrambling code WFRFT matrix and the rows of the inverse transformation matrix have orthogonality, different signals are processed by using different columns of the chaotic scrambling code WFRFT matrix, and the processed signals are transmitted as a data carrying AN; and meanwhile, a group of extra ANs are processed by using the column of the chaotic scrambling codeWFRFT and then are sent together. According to the method, the original DFT multiplier is adjusted by utilizing the pseudo-random sequence generated by the chaotic system, so that the hopping of thesubcarrier frequency is realized, and external interference or interception of other parties is effectively resisted; a constellation diagram of the constructed chaotic scrambling code WFRFT combinedsignal generates random splitting, rotation and diffusion, and interception based on a spectral feature recognition means is avoided; detection based on energy and a matched filtering method is avoided.

An apparatus for wireless communication includes a receiver configured to receive control information associated with a non-coherent transmission to a base station. The apparatus further includes a transmitter configured to perform the non-coherent transmission based on the control information. The non-coherent transmission includes transmission of a codepoint to the base station, and the codepoint is determined based a diagonalized base sequence parameter matrix, a first discrete Fourier transform (DFT) matrix of a first size, and a second DFT matrix of a second size.

Methods, systems, and apparatus for wireless communication are described. As part of a two-step random access procedure, a user equipment (UE) may transmit a random access preamble to a base station. The UE may generate a preamble by identifying a discrete Fourier transform (DFT) matrix and generating a set of sequences based on the DFT matrix. Each sequence in the set of sequences may be generated by selecting a column of the DFT matrix and performing deterministic sampling on respective entries from the selected column according to a sampling function. The UE may then select a sequence from the set of sequences based on generating the set of sequences. The UE may transmit the selected sequence to a wireless device (e.g., a base station).

The invention provides a PDP estimation method and system in NR based on a TRS, and relates to the technical field of power delay spectrum estimation, and the method comprises the steps: 1, obtaining a frequency domain channel estimation value according to a system instruction; 2, after the frequency domain channel estimation value is obtained, obtaining an observation matrix pi; 3, taking the N-dimensional DFT matrix as a sparse matrix, and obtaining a specific multipath position and multipath power through a compressed sensing algorithm, thereby obtaining accurate PDP estimation; 4, after the observation matrix II is selected in the step 2, the observation matrix II can be obtained by the rest pilot frequencies through the random generation method again, repeating the step 2 and the step 3 again, obtaining PDP estimation, two estimation results being averaged, and obtaining a better estimation result; finally, an observation matrix II is selected in the fourth step, and the PDP estimation frequency is determined according to performance requirements. According to the method, the accuracy of PDP estimation can be improved, the robustness is higher, and the complexity is reduced.