78results about How to "Good autocorrelation" patented technology

The method is applicable to long-term evolution system. The idea of the invention is that combination of time division multiplex (TDM) and frequency division multiplex (FDM) is adopted in RACH design, and combinations of multiple code words are adopted for RACH precursor. Relative to individual FDM, TDM, and CDM (code division multiplexing), technical scheme of the invention can obtain larger number of access users, and reduce interference between multiple users, and multiple sectors, use less number of correlator, and lowers complexity of sequence design.

The invention discloses a 5G waveform system synchronization method based on index modulation. The method comprises the following steps: dividing sending end parallel data of a filter orthogonal frequency division multiplexing system based on index modulation into index bit data and constellation modulation data, performing sub-band matching filtering processing, cyclic prefix removal and Fouriertransform at a receiving end, detecting the position of an activated sub-carrier, estimating an index bit, and demodulating constellation symbol information; establishing a training sequence based ona pseudo-random sequence and a Zadoff-Chu sequence, and performing timing and frequency offset estimation based on a pilot frequency data aided method; and completing timing estimation, performing fractional frequency offset estimation, performing integer frequency offset estimation by using the power difference between the activated subcarrier and the silent subcarrier, determining a receiving end Fourier transform starting window according to timing estimation information, determining a receiving end demodulation carrier frequency according to an estimated frequency offset value, and completing system synchronization. According to the invention, on the premise of not reducing the transmission efficiency, the influence of frequency offset on the system performance is effectively reduced.

This invention discloses a spread spectrum communication system and a centerless wireless network applying different phase sequences of a single spread spectrum code to realize CDMA. Said system includes a satellite receive clock pick-up unit, a clock synchronous unit, a control time-slot generation unit, a match unit a related multipath selection unit, a demodulation unit, a control process unit, a PN code set generator, a code multipath selection unit, a spread spectrum modulation unit and a duplexer, among which, the clock receive unit receives wireless signals for the system, and picks up clocks for the system, the clock synchronous unit generates code slice clock pulses synchronized to the data clock, the match receive unit receives wireless signals to generate multipath matched signals, the related multipath selection unit selects related values in an assigned time slot to be output to the demodulation unit, which finishes the demodulation of the information carried by related peaks, the control unit fetches the related data values in the assigned time slots to deal with data in a period and judge the pulse levels of related peaks and selects suitable phase sequences as the spread spectrum codes for emit signals based on the channel used situation or selects phase sequence as the local spread spectrum code used in the reception.

The invention relates to an OFDM (Orthogonal Frequency-Division Multiplexing) training sequence construction method and synchronization method, comprising the following steps: a PN (pseudo-noise) sequence is utilized to construct a sequence with a front and back repetition conjugate symmetric structure; weighting treatment is performed on the sequence, and a training sequence with a transmitting terminal used for synchronization is obtained; a receiving terminal defines a timing metric function, and symbol timing synchronization is finished by searching the maximum of the timing metric function; an estimation of fraction frequency offset is obtained by computing a phase difference of two front and back repetition parts of the received training sequence; an estimation of integer frequency offset is finished by utilizing the influence of integer frequency offset on correlated characteristics of a training sequence frequency domain. The OFDM training sequence construction method and synchronization method eliminates the influences of side peaks and peak platforms on synchronization, which are caused by symmetrical structure sequences and cyclic prefixes in a traditional synchronization method, so that the timing synchronization accuracy rate is higher, the estimation of synchronization frequency offset has a smaller error of mean square, and the OFDM training sequence construction method and synchronization method can be effectively used for time and frequency synchronization of an OFDM system in a multipath fading channel.

The method for simulation generation of wind power times series based on an improved Markov chain comprises: dividing historical wind power time series into different data slots according to different months and time frames, and calculating the state-transition matrix of each data slot; fitting the probability distribution of the historical wind power fluctuation quantity, and generating a set of random numbers satisfying the distribution; taking a historical wind power average value as a zero moment value prior to the beginning of simulation of the wind power series, in the calculated state-transition matrixes of the improved Markov chain model, according to the months and time frames of the previous time of the simulation of the wind power, determining corresponding state-transition matrixes, generating accumulative state-transition matrixes, and obtaining the state of the wind power at the current moment, namely an interval where the wind power is located; and extracting the fluctuation quantity, overlapping the fluctuation quantity on the wind power value of the previous time as the wind power value of the current moment, and generating the wind power value at the next moment in a similar way until generating the wind power time series requiring the number of data.

Provided is a method for synchronizing a multiple carrier receiver to receive a transmitted signal. The method includes determining a location of one or more scattered pilot carriers in a received symbol sequence and modulating the scattered pilot carriers in accordance with a single pseudorandom binary sequence. The method also includes performing phase error correction via the modulated scattered pilot carriers.

The invention discloses a network coding feedback method for a coordinated multi-point transmission system, which belongs to the technical field of communication. Information such as pre-coding matrix indicator (PMI) information required to be fed back and own information such as reference signal (RS) information periodically to be transmitted are subjected to network coding and then transmitted. A network coding concept is introduced to simultaneously transmit feedback information under the condition of keeping constant conventional uplink transmission overhead. A transmitted information sequence subjected to the network coding still has relatively higher cross correlation and autocorrelativity, so a receiver obtains the PMI information by a correlation detection and minimum Euclidean distance searching method, and own information required to be fed back is hidden in a sounding RS (SRS) sequence subjected to the network coding in a network coding way by taking SRS information required to be transmitted by the system as a carrier to improve the transmission effectiveness and effectively improve the throughput of the system by reducing even eliminating feedback overhead.

Aiming at the shortage of the current tidal current velocity research, the invention provides a tidal velocity prediction method based on a fractal theory and an improved least square support vector machine, which has the characteristics that the intermittency and uncontrollability of tidal energy are the main characteristic causing randomness of generator output power, the tidal velocity time series is a nonlinear system with fractal characteristics, by taking historical data as a research object, based on the fractal theory, the Hurst exponent and V statistic of time series are calculated byadopting an R/S analysis method, and the stability and autocorrelation of tidal current are evaluated. A tidal current prediction model is established based on the parameters of the improved least square support vector machine optimized by a dragonfly algorithm for predicting the tidal current. The prediction method can effectively judge the autocorrelation of the tidal velocity, provides the theoretical basis for the prediction of the tidal velocity, and effectively improves the prediction accuracy and the operation efficiency through the improved prediction model.

The invention discloses a symbol timing synchronization method of an OFDM system. With the method, problems that no single sharp timing offset estimation function peak value is provided in the prior art and too much time is spent in determining an ideal timing position can be solved. The method comprises the following steps: 1, generating a training sequence and inserting the training sequence in front of a load data packet; 2, calculating a timing offset estimation function value at an initial position time of a sliding window at a receiving terminal; 3, taking an average of timing offset estimation functions of M times before the time at any time; 4, determining a weighting coefficient of the timing offset estimation function average value; 5, calculating a dynamic threshold according to the obtained timing offset estimation function average value and weighting coefficient; and 6, comparing the timing offset estimation functions and the dynamic threshold until detecting an ideal timing position of the current load data packet; and carrying out the operation continuously according to the mechanism to obtain an ideal timing position of each subsequent data packet. Therefore, timing can be realized accurately in a low-signal-to-noise-ratio environment and the real-time performance is good.

A pulse sequence is produced by repeatedly selecting individual pulse trains at random from a set thereof, each pulse train meeting predetermined autocorrelation constraints and the pulse trains collectively meeting predetermined cross-correlation constraints. The pulse trains are preferably separated by gaps of random length. At least some pulse trains may be time-reverse replicas of others. The resulting sequences are particularly suitable for obstacle detection in multiuser environments.

The invention discloses a method for generating leading signals of power line carrier communication systems on the basis of OFDM (orthogonal frequency division multiplexing) modulation. The method includes steps of S1, setting characteristic parameters of OFDM symbols; S2, designing a group of long binary pseudo random sequences PN (pseudo noise) <L> with the lengths of NL according to IFFT (inverse fast Fourier transformation) point numbers N; S3, primarily mapping BPSK (binary phase shift keying) symbols of the pseudo random sequences PN<L> to obtain BPSK modulation signals and filling corresponding effective sub-carriers with the BPSK modulation signals; S4, carrying out discrete fast Fourier inverse transformation on the BPSK modulation signals to obtain OFDM basic signals; S5, designing a group of binary short sequences PN<S> with the code lengths of NS; S6, carrying out BPSK modulation on the short sequences PN<S> to obtain short sequence symbols; S7, jointly modulating the OFDM basic signals by the aid of the short sequence symbols to obtain joint modulation signals of NS sections; S8, determining the leading signals according to the joint modulation signals of the NS sections. The characteristic parameters include the IFFT point numbers. The method has the advantage that the method is applicable to complicated multi-path channel environments of power lines.

The invention relates to a linear frequency modulation anchor rod detection receiving and sending integral sensor, which comprises a sensor casing, an acceleration signal receiver and a plurality of piezoelectric ceramic emitting arrays, wherein the piezoelectric ceramic emitting arrays are uniformly arranged on the bottom surface of the sensor casing in the circumferential direction; the acceleration signal receiver is arranged in the axis center of the bottom surface of the sensor casing; the sensor casing is used for being installed on the excitation surface of the exposed end part of the tested anchor rod; the signal input ends of the plurality of piezoelectric ceramic emitting arrays are used for accessing chirp signals; the signal output end of the acceleration signal receiver is thesignal output end of the linear frequency modulation anchor rod detection receiving and sending integral sensor. The linear frequency modulation anchor rod detection receiving and sending integral sensor has the advantages that the emitting frequency band is wide; the energy is great; the penetration power is high; the attenuation is small; the self relevance is good; the action distance is great; the detection is easy; the size is small and the control is easy.

The invention discloses an improved binary coded symbol (BCS) modulation method based on a minimum shift keying (MSK) pulse. On the basis of BCSs, spread spectrum symbols are split into n units, a symbol pulse waveform of MSK is adopted in each unit to replace a binary value waveform, and an optimized BCS sequence is finally obtained for modulation. According to the method, by optimizing the BCS sequence with good self-correlation performance, the BCSs can be good in self-correlation characteristic, good in anti-interference performance, good in anti-multipath performance and high in compatibility, and the characteristics of constant envelope, improved power amplification efficiency, high side lobe attenuation and the like of MSK modulation can be achieved.

The invention discloses a transform domain underwater acoustic communication method based on chaotic spread spectrum, and the method comprises the following steps: S1, carrying out sampling of an environment channel at a transmitting end and a receiving end, obtaining an environment noise signal, and carrying out the FrFT processing of the environment noise signal, and obtaining an environment spectrum vector; S2, obtaining a double-chaotic sequence through an improved Logistic mapping structure, processing the double-chaotic sequence, and obtaining a pseudo-random phase through FrFT; S3, after the environment spectrum vector is matched with the pseudo-random phase, carrying out amplitude adjustment to obtain an FrFT domain basis function, and carrying out IFrFT on the FrFT domain basis function to obtain a time domain basis function; S4, performing baseband mapping on the time domain basis function of the transmitting end at the transmitting end to obtain a spread spectrum signal, and sending the spread spectrum signal to a receiving end; and S5, performing related demodulation on the spread spectrum signal at a receiving end through a time domain conjugate basis function of thereceiving end to obtain an information signal. The method has better concealment, anti-interference capability, anti-multipath capability and the like, and can realize reliable communication under a very low signal-to-noise ratio.

The invention provides a method and a system for determining the state parameters of a measured object. The method includes the following steps: at an acoustic transmitter, generating an acoustic signal, multiplying the acoustic signal by a spread spectrum pseudo-random code to obtain an acoustic ranging signal, sending out the acoustic ranging signal, and extracting the acoustic characteristic parameters of the acoustic transmitter; at an acoustic receiver, capturing the acoustic ranging signal, and extracting the acoustic characteristic parameters of the acoustic receiver; and detecting thestate parameters of a measured object based on the acoustic characteristic parameters of the acoustic transmitter and the acoustic characteristic parameters of the acoustic receiver. The spread spectrum technology is applied to acoustic measurement, and therefore, the state parameters of the measured object can be measured more accurately.

The invention discloses an OFDM-PON physical layer encryption method based on three-dimensional Arnold transformation of conservative digital chaos, and the method comprises the steps: S1, generatinga chaos sequence at a transmitting end through employing an initial value of a conservative digital chaos system, adding disturbance to the generated chaos sequence, expanding the chaos sequence intoa plurality of groups of chaos sequences, and carrying out the PCA processing of the chaos sequences, selecting a chaotic sequence of the first principal component; S2, controlling parameters of three-dimensional Arnold transformation by using the chaotic sequence of the selected first principal component, and performing first-layer encryption on the OFDM signal; S3, randomly extracting and generating a chaotic Frank matrix through a Frank sequence, performing second-layer encryption on the OFDM signal, converting the signal subjected to secondary encryption into an optical signal through an electro-optical modulator, and transmitting the optical signal to a receiving end through an optical fiber channel; and S4, converting the optical signal into an electric signal through a photoelectricdetector at a receiving end, decrypting the encrypted electric signal by utilizing the secret key, and outputting original data.

The invention discloses a timing synchronization method and device. Th method includes: performing sliding cross-correlation on the received time domain data and a pre-stored main synchronization sequence; obtaining a correlation value sequence corresponding to each pre-stored main synchronization sequence; directly mapping the pre-stored main synchronization sequence into a time domain sequence from a ZC sequence, wherein the main synchronization sequence generated in this way has better autocorrelation and cross-correlation characteristics in the time domain; secondly, dividing the correlation value sequence into a plurality of segmented sequences, calculating a segmented peak-to-average ratio of each segmented sequence, and finally determining a synchronous index position as a timing synchronous position according to the segmented peak-to-average ratio, namely, the synchronous index position is an index position of a maximum correlation value in the synchronous segmented sequence, and the synchronous segmented sequence is the segmented sequence with the maximum segmented peak-to-average ratio. According to the timing synchronization method provided by the invention, the correlation value sequence is solved, and the interference signal is filtered out by combining the calculation of the peak-to-average ratio, so that the timing synchronization position is determined, the error synchronization caused by overlarge interference is avoided, and the reliability of the timing synchronization is improved.