99 results about "Long code" patented technology

A method and arrangement are disclosed for processing a compressed media signal, for example, embedding a watermark in an MPEG2 video signal. The watermark, a spatial noise pattern (140), is embedded (123) by selectively discarding the smallest quantized DCT coefficients. The discarded coefficients are subsequently merged in the runs of other run/level pairs. To compensate for a too large reduction of the bit rate, some of the new run/level pairs are not variable-length encoded (124) but represented by longer code words according to further coding rule (125) providing such longer code words, for example, MPEG's "Escape coding".

The invention discloses a source code vulnerability detection method for code graph representation learning based on a graph convolution network. The method comprises the following steps: generating acode attribute graph; adding a function calling relationship and an inter-process dependency relationship into the code attribute graph; obtaining code slices according to the vulnerability key points; deleting nodes in the graph by utilizing slices, and extracting graph structure information related to vulnerabilities; learning vector representation of each node by using a graph convolution network; dividing the sub-graphs according to the types of the edges, and obtaining vector representation of the graphs through a READOUT model based on an attention mechanism; adjusting network parameters according to the vector representation and the label of the graph; and detecting the code vulnerability by using the trained model. According to the method, the structure and attribute information of the vulnerability code can be fully utilized and learned, the problems that code structure information is easy to lose when a traditional deep network learns code representation and long code context information is lost due to the fact that the code needs to be represented as a fixed length sequence are avoided, and false alarm and missing alarm of vulnerability detection are reduced.

System and method for decoding variable-length codes. A variable-length decoder includes an address generator and a local memory unit. The local memory stores a variable-length code look-up table. The local memory can be programmed to include a look-up table supporting substantially any decoding algorithm. In one embodiment, a decoder memory unit and a system memory unit are employed together with the local memory to store a codeword look-up table. The shortest codes are stored in local memory, the next shortest in decoder memory, and the longest codes are stored in system memory. A multistage search algorithm is employed to search for the longest codes. The address generator generates the address of the code table to be searched by adding the value of the bits to be searched to a base address.

The invention discloses an application file verification method and system. The method comprises the steps that a mobile device obtains a first check code and a second check code of an application file, wherein the first check code is obtained according to first authorization file information carried by the application file, and the second check code is obtained according to second authorization file information carried by an authorized edition of the application file; and the mobile device determines that the application file passes the verification when the first check code is consistent with the second check code. Through the method and the system, the security of the application file can be determined at a mobile terminal and relatively long codes do not need to be input.

In a handover from an asynchronous radio network to a synchronous system, long code state information and activation time are transmitted. The method of transmitting long code state information and activation time includes the step of acquiring handover-related information from a neighboring synchronous system by the asynchronous radio network. In the handover, the synchronous system transmit a first message including activation time information and long code state information to the mobile station by the asynchronous radio network and after receiving the activation time information and the long code state information, makes use of the long code state information based on the activation time information by the mobile station.

The invention discloses a DS/FH frequency-hopping spectrum-spreading data transmission signal capturing method based on long code phase assistance, capable of solving the technical problems of relatively high cost and low efficiency of an existing method for keeping system synchronization for a DS/FH frequency-hopping spectrum-spreading hybrid system. Based on a local oscillator, the following steps are implemented: S100, carrying out carrier stripping on a signal at a set frequency hopping frequency point; S200, calculating code phase shift and Doppler shift of the signal at the current frequency hopping frequency point based on the step S100; S300, realizing synchronization of frequency hopping patterns based on the step S200; and S400, calculating Doppler shift of the signal at all frequency hopping points. According to the DS/FH frequency-hopping spectrum-spreading data transmission signal capturing method, the problem that receivers cannot be synchronized due to inconsistent Doppler shift of different frequency hopping points is solved; the DS/FH frequency-hopping spectrum-spreading data transmission signals based on long code phase assistance are captured, and the complexityis low, and implementation is flexible. The DS/FH frequency-hopping spectrum-spreading data transmission signal capturing method can effectively reduce the calculation amount and average capture time,improves the capture speed, can be used for capturing spectrum-spreading signals, and is higher in anti-interference capability.

There is provided an information management apparatus which can make it impossible to read out data recorded on a write-once type recordable optical disk as required and the usefulness thereof is enhanced. When recorded data is destroyed on the write-once type recordable optical disk, data modulated by a modulation system of the same run length restriction as run length restriction of a modulation system used for recording data is overwritten and recorded, data is overwritten and recorded by use of patterns in which the frequency of occurrence of spaces of the longest code is higher than the frequency of occurrence of the modulation system used for recording data, or data is overwritten and recorded by use of successive patterns of the shortest code in the run length restriction of the modulation system used for recording data.

The embodiment of the invention provides an LDPC decoding method and system, an electronic device and a storage medium. The method comprises the following steps of establishing a relation curve graphbetween the peak _ BER and a correction factor alpha and an offset factor beta; determining that alpha and beta are optimal when peak _ BER is maximum, calculating the optimal log-likelihood ratio (LLR) information transmitted to a variable node by a check node according to the optimal alpha and beta, and further calculating the optimal log-likelihood ratio (LLR) information transmitted to the check node by the variable node; and trying to judge a coded parameter in an original code word sequence c, if a formula is satisfied, outputting the coded parameter, otherwise updating the SNR in the current communication environment so as to update alpha and beta until the formula is satisfied, and outputting the coded parameter, wherein H is an extended parity check matrix. According to the embodiment of the invention, the offset factor beta and the normalization factor alpha are adjusted dynamically by combining the parameters, such as the signal-to-noise ratio SNR, a long code block length B, a code rate R, etc. and further the optimal decoding sequence is obtained.

The invention provides a GNSS long code signal capturing method and device assisted by a low earth orbit satellite. The GNSS long code signal capturing method assisted by the low earth orbit satellitecomprises the following steps: acquiring GNSS baseband signals; performing frequency mixing operation; performing segment correlation operation; performing long-time coherent integration; carrying out incoherent integral operation; and performing peak detection and threshold judgment. The method and the device have the advantages that GNSS navigation signal auxiliary information, including roughDoppler information and rough code phase information, is acquired under the assistance of a low-orbit satellite, so that on one hand, the rough code phase information is used for generating sub-codesof local ranging codes and participating in related operation; it is guaranteed that the influence of bit hopping on coherent integration time is eliminated after correlation operation, high-sensitivity capturing of long codes is achieved through long-time coherent integration, and the long code signal capturing performance in the low signal-to-noise ratio environment is improved; and on the otherhand, rough Doppler information and rough code phase information of the GNSS navigation signals are utilized, the searching time of the signals in the frequency dimension and the code dimension is shortened, the capturing efficiency is improved, and rapid capturing of GNSS long code signals is achieved.

The invention discloses a method and a system for capturing an aperiodic long code signal of a satellite navigation receiver. The method comprises the following steps: S1, in a rapid search stage, carrying out segmented correlation accumulation by using relatively short coherent integration time, carrying out rapid Fourier transform, envelope taking and post-accumulation processing on a segmented correlation value, and maximizing a frequency spectrum envelope to obtain a Doppler frequency initial estimation value under a current code phase; s2, a false alarm verification stage: accumulating a plurality of segmented correlation values after phase rotation in the fast search stage to obtain a segmented correlation value with longer coherent integral time, similarly performing fast Fourier transform, envelope taking and post-accumulation processing, performing capture judgment by using a spectrum envelope maximum value, and when the envelope maximum value exceeds a capture threshold, performing false alarm verification, outputting the current code phase and Doppler frequency as a signal capturing result. Under the condition that the Doppler search range is guaranteed, high detection performance can be achieved, and two-stage detection is achieved under the condition that correlator resources are not increased.

The present invention discloses a method for controlling a toe-end sliding sleeve in a horizontal well based on efficient decoding communication. The method comprises the following steps: forming a pressure wave signal by adjusting and controlling a pressure value in a wellbore according to a first preset encoding manner; acquiring a pressure value change signal in the wellbore, determining a reference time by using an STA/LTA method, and predicting pressure value to acquire a predicted pressure value signal curve; identifying a toe-end sliding sleeve control command in the acquired pressure wave signal by using a first preset decoding manner based on the fitness between the acquired pressure value signal curve and the predicted pressure value signal curve; and driving the toe-end sliding sleeve to perform actions according to the toe-end sliding sleeve control command. The method disclosed by the present invention is simple to operate, low in communication error rate, and aimed to solve the technical problems of complicated system of wellbore pressure test and sliding sleeve joint operation, high operation complexity, high bit error rate of pressure pulse communication, and long code element transmission time in the existing solutions in the prior art.

The invention belongs to the technical field of signal processing, and particularly relates to an aperiodic long-code direct sequence spread spectrum signal time delay estimation method and system based on norm fitting, and the method comprises the steps: carrying out the carrier synchronization and timing synchronization of a received signal, and obtaining an aperiodic long-code direct sequence spread spectrum CDMA baseband waveform; modeling the long code direct sequence spread spectrum signal into a short code direct sequence spread spectrum signal containing missing observation, rearranging the baseband waveform into a missing data matrix according to the code element width of the information code, and obtaining an F norm curve of the missing data matrix; setting an equivalent period,representing the missing data matrix as cyclic repeat representation of a cellular matrix, and obtaining a user signal F norm curve square template according to the cellular matrix and the screening matrix; and modeling the multi-user signal F norm curve as cyclic convolution of a template curve, and solving the model by using a least square method to obtain an out-of-step time parameter of each user. According to the method, the time delay estimation of the high-capacity asynchronous NPLCDSSSCDMA system under the non-cooperative receiving condition can be realized, and the operation complexity of the system is effectively reduced while the good estimation precision is ensured.

The invention discloses a polar code adaptive decoding method and system, and belongs to the field of wireless communication. The method comprises the following steps: firstly constructing and training a neural network, and inputting to-be-decoded path information into the neural network to obtain the maximum path number of each layer; and inputting the maximum path number of each layer into a decoder, and decoding the path information to be decoded by using the decoder to obtain a decoding result. The system comprises a neural network unit and a decoding unit, wherein the neural network unitis electrically connected with the decoding unit; the decoding unit comprises a path expansion unit and a sorting unit, the path expansion unit is electrically connected with the sorting unit, and thepath expansion unit is electrically connected with the neural network unit. The invention aims to overcome the defects that in the prior art, a decoding algorithm based on deep learning is high in training complexity and not suitable for long code application, the decoding complexity can be reduced, and different channel environments and configuration requirements of a communication system can bemet.

Disclosed is a method for generating a public long code mask (PLCM) so that a mobile station can receive a Broadcast/Multicast Service (BCMCS), in a mobile communication system including a base station and at least one mobile station located in a cell occupied by the base station, the BCMCS being provided from the base station to the mobile station. The PLCM is created by a combining a BCMCS flow identifier (BCMC FLOW ID) and a BCMC service reference identifier (BSR ID) matched thereto from a BCMCS service parameter message (BSPM) including information related to the BCMC FLOW IDs indicating individual flow IDs for identifying flows from respective broadcasting stations and BSR IDs matched to the BCMC FLOW IDs, the BSPM being transmitted from the base station to the mobile station over at least one channel.

Systems and methods for retrieving similar multivariate time series segments are provided. The systems and methods include extracting a long feature vector and a short feature vector from a time series segment, converting the long feature vector into a long binary code, and converting the short feature vector into a short binary code. The systems and methods further include obtaining a subset of long binary codes from a binary dictionary storing dictionary long codes based on the short binary codes, and calculating similarity measure for each pair of the long feature vector with each dictionary long code. The systems and methods further include identifying a predetermined number of dictionary long codes having the similarity measures indicting a closest relationship between the long binary codes and dictionary long codes, and retrieving a predetermined number of time series segments associated with the predetermined number of dictionary long codes.

In an asynchronous CDMA communication system using long codes, multiple access interference can be reduced. In one aspect, Parallel Interference Cancellation (PIC) performs decoupled estimation, preferably non-linear and applied to chip spacing. According to another aspect, interference is canceled using a technique that estimates bits in a symbol by interpolating a user's signature waveform into a common sampling grid of received data. According to another aspect, multi-stage, hybrid multi-stage and reconfigurable recursive multi-stage multi-user detection structures and corresponding processing may be provided.

The embodiment of the invention provides a hybrid spread spectrum communication method and device based on long and short codes, and the method comprises the steps: splicing link synchronization dataand frame synchronization data into synchronization segment data, and carrying out the spread spectrum processing of the synchronization segment data through a short code sequence; splicing the frameheader data, the data domain data and the frame tail data into information segment data, and performing spread spectrum processing on the information segment data by using a long code sequence; and splicing the spread-spectrum synchronous segment data and the spread-spectrum information segment data, and sending the spliced synchronous segment data and spread-spectrum information segment data. Byapplying the method of the invention, the system user capacity is effectively improved.

The invention discloses a convolutional code decoding method and a convolutional code coding and decoding method based on bidirectional LSTM, belongs to the technical field of electronic communication, and solves the problems that the time complexity and the space complexity of traditional coding and decoding are exponentially increased along with the increase of the code length and the constraint degree, a long code codebook is difficult to select, coding information is easy to intercept and crack, and the decoding efficiency is low. And the safety is low. The method comprises the following steps: constructing a bidirectional LSTM neural network decoder, wherein the neural network decoder adopts a bidirectional LSTM neural network to decode; establishing a receiving sequence data set, and constructing a training codebook according to the receiving sequence data set and the bidirectional LSTM neural network; selecting a training signal-to-noise ratio, wherein the training signal-to-noise ratio is the signal-to-noise ratio of the receiving sequence; simulation parameters are set, and the bidirectional LSTM neural network decoder is trained by using the training codebook and the training signal-to-noise ratio; and decoding by using the trained bidirectional LSTM neural network decoder. The end-to-end convolutional code coding and decoding method is suitable for end-to-end convolutional code coding and decoding.