79 results about "Tanner graph" patented technology

A method for communicating binary data and a digital communication system are presented. According to one embodiment, the method includes encoding a message word by multiplying the message word with a generator matrix, wherein the generator matrix multiplied by the transpose of a parity check matrix for a low density parity check code yields a null set, and wherein the parity check matrix has a column weight of two. Additionally disclosed is an encoding scheme based on a three-tier Tanner graph having a girth of twelve.

The invention discloses a channel-polarization-based encoder for a staggered structure duplication code, and an encoding method and decoding methods thereof. The encoder consists of a duplication bit buffer with a storage capacity of L bits, a bit position mapper with a length N and a channel polarization device with the length N which are connected in sequence. The encoding method based on the encoder comprises the following steps of: embedding duplicated encoding into a channel polarization process, and introducing a duplicated relationship between parts of the bits of code blocks transmitted in sequence during the channel polarization for encoding. In addition, the invention further provides two decoding methods, which comprise the following steps of: decoding by using a simple and rapid successive cancellation (SC) algorithm, and performing iterative decoding by using a Tanner-graph-based belief propagation algorithm with excellent performance. On the basis of the innovative structure encoder, the encoding and decoding methods provided by the invention are stronger in error correction capability under the condition of not increasing the decoding complexity, and the transmission performance is obviously improved. The encoding and decoding methods are particularly applicable to an actual communication engineering system and have a good popularization and application prospect.

The present invention is intended to provide an LDPC coding scheme which is capable of efficiently implementing a high-performance and high-speed encoder and decoder of an error correcting code suitable for the field of communications such as mobile communications. As to the configuration, a Tanner graph for representing codes with variable nodes and check nodes is used to classify the individual nodes into a plurality of categories. For calculating a probability propagation in iterative decoding, weighting previously determined for each category is performed on a log-likelihood ratio (LLR) subjected to propagation.

An LDPC code encoding apparatus includes: a code matrix generator for generating and transmitting a parity-check matrix comprising a combination of square matrices having a unique value on each row and column thereof; an encoding means encoding block LDPC codes according to the parity-check matrix received from the code matrix generator; and a codeword selector for puncturing the encoded result of the encoding means to generate an LDPC codeword. The code matrix generator divides an information word to be encoded into block matrices having a predetermined length to generate a vector information word. The encoding means encodes the block LDPC codes using the parity-check matrix divided into the block matrices and a Tanner graph divided into smaller graphs in correspondence to the parity-check matrix.

A method for communicating binary data and a digital communication system are presented. According to one embodiment, the method includes encoding a message word by multiplying the message word with a generator matrix, wherein the generator matrix multiplied by the transpose of a parity check matrix for a low density parity check code yields a null set, and wherein the parity check matrix has a column weight of two. Additionally disclosed is an encoding scheme based on a three-tier Tanner graph having a girth of twelve.

The current invention involves a forward error detection system, especially for use with Low Density Parity Check codes. A parallel SISO structure allows the decoder to process multiple parity equations at the same time. There is a new SISO decoder which allows for the updating of the Log-likelihood-ratios in a single operation, as opposed to the two pass traditionally associated with the Tanner Graphs. In the decoder, there is a mapping structure that correctly aligns the stored estimates, the stored differences and the SISOs. There is also the ability to deal with multiple instances of the same data being processed at the same time. This structure manages the updates and the differences in such a manner that all calculations on a single piece of data that are processed in parallel are incorporated correctly in the new updated estimates.

An LDPC code encoding apparatus includes: a code matrix generator for generating and transmitting a parity-check matrix comprising a combination of square matrices having a unique value on each row and column thereof; an encoding means encoding block LDPC codes according to the parity-check matrix received from the code matrix generator; and a codeword selector for puncturing the encoded result of the encoding means to generate an LDPC codeword. The code matrix generator divides an information word to be encoded into block matrices having a predetermined length to generate a vector information word. The encoding means encodes the block LDPC codes using the parity-check matrix divided into the block matrices and a Tanner graph divided into smaller graphs in correspondence to the parity-check matrix.

A decoder for performing soft decision iterative decoding of a cyclic code based on belief propagation, includes an information exchange control unit, an X processor, and a Z processor. The information exchange control unit takes pix-metrics that were calculated by the X processor for nonzero elements in each of n-cyclic shifts of the parity-check polynomial of the code, and distributes the pix-metrics to the Z processor as the piz-metrics for a corresponding check node. The information exchange control unit takes lambdz-metrics that were calculated by the Z processor for nonzero elements in each of n-cyclic shifts in a reverse order of the parity-check polynomial, and distributes them to the X processor as lambdx-metrics for the corresponding code node. The operation of the information exchange control unit can be represented by the Tanner graph associated with an extended parity-check matrix, which is produced by adding k rows to the parity-check matrix of the cyclic code, wherein the X processor functions as the code nodes and the Z processor functions as the check nodes.

The invention relate to the technical field of channel coding of a wireless communication system and a satellite communication system, and provides a method for constructing a code-rate compatibility QC-LDPC code on basis of matrix row deletion. The method includes the steps that firstly, on the basis of a GCDg8 algorithm, QC-LDPC codes with a large girth and a low code rate are constructed to serve as primary codes, then successive row deletion of an exponential matrix is carried out to obtain subcodes with a high code rate and an unchanged information bit length, and the short-length problem of code words with a high code rate is avoided; row deletion means that corresponding edges of Tanner graphs corresponding to the primary codes without the short-length problem are deleted, the short-length problem cannot occur, and the girth may increase; ultimately, the subcodes are processed through a hidden technique, the minimal distance of the code words is increased, and performance of the code words is improved. According to the method, the code-rate compatibility QC-LDPC code with structural design is adopted, and compared with an LDPC code constructed in a PEG algorithm, construction is easier to achieve, hardware achievement complexity is not high, and performance is more excellent.

A method and system for communicating signal data in GNSS system using LDPC convolution codes. The method involves, at transmitting end, formatting signal data into a set of subframes. Each subframe of the signal data can be encoded in accordance with a parity check matrix defining Tanner graph representation of LDPC convolution codes. The encoded signal data can be interleaved and added with a Sync word field to transmit an interleaved block of encoded signal data through a communication channel. At receiving end, the interleaved block of encoded signal data can be de-interleaved after it is received from the communication channel. The Tanner Graph shows the connectivity in time invariant parity check matrix. A message passing technique is used to decode the LDPCCC encoded message. The encoded signal data can be decoded through the message passing technique to obtain the signal data primitively transmitted at the transmitting end. Such method and system are capable of achieving error free performance over the GNSS communication channel for effective navigation data communication, and also provide good BER performance over a wide range of Signal-to-Noise ratios.

The invention discloses a Raptor Codes encoding / decoding method suitable for medium / short code lengths of an additive white Gaussian noise channel. According to the method disclosed by the invention, the degree distribution of the inner codes, i.e. LT (Linear-Time) Codes, of the Raptor Codes which are more suitable for the medium / short code lengths is proposed; and the improved PEG (Progressive Edge-Growth) algorithm is used for encoding the inner codes, i.e. the LT codes, of the Raptor Codes, wherein the encoding manner consists of two PEG encoding manners, i.e. independently carrying out PEG composition on the LT Codes and carrying out the PEG composition on the LT Codes through combining with outer codes, i.e. LDPC (Low Density Parity Check) Codes, thus the problem that excessive shortloops appear in a Tanner graph, caused by randomly selecting information packets in an LT encoding stage, is solved. With the adoption of the method disclosed by the invention, the effectiveness for the transfer of soft information when the BP (Background Processing) iterative decoding is carried out is therefore enhanced, the performance better than that of a random composition manner is obtained, and the more reliable transmission for the rateless codes with the medium / short code lengths is realized.

An operation method of a LPC decoder includes: initializing variable nodes of a Tanner graph representing a parity check matrix; performing a check node update to check nodes of the Tanner graph based on variable node values of the variable nodes; performing a variable node update when there are USC nodes among the updated check nodes as a result of the check node update; and repeating the performing of the check node update and the variable node update when there are USC nodes as the result of the check node update, wherein the performing of the variable node update includes: selecting among the variable nodes a predetermined number of variable nodes having a USC value greater than a threshold; and flipping the variable node values of the selected variable nodes, and wherein the USC value is a number of the USC nodes linked to one of the variable nodes.

A Low Density Parity Check (LDPC) code encoding apparatus for a communication system is provided. The encoding apparatus receives information bits, and generates an LDPC code by encoding the information bits using an interleaving scheme. The interleaving scheme is generated such that when the LDPC code is punctured, there is no short-length cycle in a Tanner graph of the punctured LDPC code.

The invention discloses a Raptor code (with non-regular codes as precoding) optimized coding method; when the Raptor code using non-regular LDPC code as precoding is coded, different probabilities areselected for intermediate codons of different columns for LT coding, and the selection probability of the intermediate codon with the big column is properly lowered, thus relatively uniforming the total number of degrees of the intermediate codons in a Tanner graph of the Raptor code, and improving the decoding success rate.

The present invention provides a polar-LDPC (Low Density Parity Check) cascaded code merging BP (Belief Propagation) decoding algorithm and device. The device comprises an initialization module, an iteration calculation module and a hard decision module. The initialization module comprises a multiplier configured to perform channel observation vector initialization to log likelihood ratio information; the iteration calculation module comprises a multiplier groups relative to variations of a Tanner graph and a factor graph, verification nodes, a basic calculation unit and influencing factors; and the hard decision module comprises a hard decision unit configured to obtain an decoding result. In the condition that the Polar-LDPC cascaded code merging BP decoding algorithm has the same iteration times as a traditional algorithm, the influencing factors are arranged to obtain bit-error performances being obviously better than a traditional method and have no great difference in calculation complexity.

The current invention involves a forward error detection system, especially for use with Low Density Parity Check codes. A parallel SISO structure allows the decoder to process multiple parity equations at the same time. There is a new SISO decoder which allows for the updating of the Log-likelihood-ratio's in a single operation, as opposed to the two pass traditionally associated with the Tanner Graph's. In the decoder, there is a mapping structure that correctly aligns the stored estimates, the stored differences and the SISO's. There is also the ability to deal with multiple instances of the same data being processed at the same time. This structure manages the updates and the differences in such a manner that all calculations on a single piece of data that are processed in parallel are incorporated correctly in the new updated estimates.

A network re-encoding device is intended for re-encoding encoded symbols to be transmitted to at least one communication equipment connected to a network. This network re-encoding device comprises a re-encoding means arranged for re-encoding output nodes, defined by LT code symbols representative of encoded symbols and representative respectively of the results of XOR Boolean operation between input nodes defining decoded symbols whose values have to be discovered and to which they are linked into a Tanner graph, by combining chosen input node and / or output node having known values, in order to produce new LT code symbols defining generated output nodes ready to be transmitted.

The invention relates to a quasi-cyclic low-density parity-check (LDPC) code construction method. A quasi-cyclic LDPC code to be constructed is represented by a tree graph model Tanner graph, and the quasi-cyclic check matrix parameter is that the size of a basis matrix is m * n, the size of a Block matrix is p * p, and basis matrix variable nodal point dimensionality distribution is represented by dv. The method comprises the follow steps: (1) determining check nodal point homogenization dimensionality distribution (dc) according to the basis matrix variable nodal point dimensionality distribution (dv) and adding all the n variable nodal points to the Tanner graph according to the dimensionality distribution (dc); (2) adding m check nodal points to the Tanner graph line by line and selecting pre-selected variable nodal points, determining the variable nodal points reaching a weight preset value according to side boundary weight and serving as an alternative set, and obtaining the variable nodal points with avoiding degree (ADeg) equal to or larger than delay (DLY) in a screening mode from the alternative set; and (3) determining the side boundary weight in the Tanner graph according to the points obtained from the step (2), adding corresponding sides to the Tanner graph, obtaining the quasi-cyclic LDPC code according to the Tanner graph, and achieving the construction of the quasi-cyclic LDPC code.

The present inventions are related to systems and methods for an LDPC decoder with dynamic Tanner graph modification, and in particular, to a non-erasure channel LDPC decoder that implements a probabilistic approach to Tanner graph modification.

Disclosed is a method, a computer program product and an apparatus providing a novel multiple input / multiple output (MIMO) receiver. The method includes receiving a plurality of signals through a plurality of antennas, the plurality of signals being modulated with a space-time lattice code; removing an effect of a channel matrix from the received signals to provide an equalized received signal; and lattice detecting the equalized received signal based on a Tanner graph representation of the lattice. The Tanner graph representation is one where lattice points inside a shaping region of interest are partitioned into a plurality of subgroups, where each subgroup includes a plurality of different lattice points labeled by an Abelian group block codeword, and where lattice detecting operates on the subgroups. The labels of all subgroups form an Abelian block code represented by the Tanner graph, and lattice detecting further includes performing belief propagation on a corresponding non-binary label Tanner graph to yield a total a posterior probability (APP) and extrinsic APPs of the labels and their coordinates, and obtaining APPs of individual lattice points.

Provided is an LDPC encoding method for realizing an error correction code encoder and decoder suitable for the communication field of mobile communication with high performance, high speed, and high efficiency. A Tanner graph for expressing codes using variable nodes and check nodes is used to classify each node into a plurality of categories. In the probability propagation calculation in iterative decoding, for the log-likelihood ratio (LLR) to be propagated, predetermined weighting for each class is performed.

The invention relates to a code method of a channel correcting LDPC code. The existing method only solves the construction method of the LDPC code below the binary system, but not solves the DDPC construction under the multi-system modulation. The method divides the initial LDPC code into q LDPC subcode to realize the decoding result of the LDPC short code by the q-th binary iteration decoding algorithm by means of multiple decoding. The final decoding result of the initial LDPC code is obtained by a simple combination based on the modulation and interweaving mode. The obtained LDPC code doesn't appear four rings in the Tanner graph. The coding mode is multi-coding, thus the decoding is multi-decoding. The decoding in each stage adopts the decoding algorithm below the binary system so as to greatly reduce the complexity of which directly decodes the multi-system code word.

The invention relates to a combined constructing method for quasi cyclic-low density parity check codes. The method comprises the steps that firstly, two integers L1 and L2 which are relatively prime are selected, wherein L1 is a prime number, and L=L1*L2; secondly, the row weight Rho of a given code parameter is larger than or equal to 1 but smaller than or equal to L1, the column weight gamma of the given code parameter is larger than or equal to 1 but smaller than or equal to L1, and a shift matrix S(H1) of the shortened array LDPC code with the girth g larger than or equal to 6 is constructed; thirdly, a matrix S(H2) is constructed, elements in a first line and a first column are selected from the set {0,1,2,...,L2-1} at random, and the rest elements are arranged from top to bottom and from left to right one by one; fourthly, the number of g-rings, corresponding to a sparse matrix H, in a tanner graph is counted every time the S(H2) is set with one element, and the fewest elements of the g-rings serve as the elements in the column and line; fifthly, the elements in the S(H) are replaced by an L*L cyclic permutation matrix so that the sparse matrix H with the smaller number of g-rings can be obtained to serve as a check matrix of the LDPC code, the construction of the code is finished, and the QC-LDPC codes (1573,1146) and (1519,870) are obtained. The combined constructing method can obtain the QC-LDPC codes with good ring distribution and superior correcting performance and is suitable for China digital sound broadcasting.

The present inventions are related to systems and methods for an LDPC decoder with dynamic Tanner graph modification, and in particular, to a non-erasure channel LDPC decoder that implements a probabilistic approach to Tanner graph modification.

The invention discloses a blind authentication method for a frequency selective fading channel based on belief transfer. The method includes transmitting a carrier signal to the frequency selective fading channel having multiple paths, wherein the carrier signal comprises an authentication signal, a pilot signal and an information signal and the authentication signal is superimposed on the pilot signal; receiving the carrier signals, causing the carrier signal in each path to be sequentially subjected to blind known interference cancellation (BKIC) processing to obtain a target signal, causingthe target signal to be subjected to differential signal processing to obtain a target authentication signal, performing the BKIC processing by using a prior probability density function of the target signal and a Tanner graph, and eliminating the pilot signal through a belief transfer technology; obtaining a reference signal based on a key and the pilot signal, performing differential signal processing on the reference signal to obtain a reference authentication signal, calculating the correlation between the target authentication signal and the reference authentication signal, and obtaininga test statistic amount; and comparing the test statistic amount with a prescribed threshold to determine whether the carrier signal can pass the authentication.

The current invention involves a forward error detection system, especially for use with Low Density Parity Check codes. A parallel SISO structure allows the decoder to process multiple parity equations at the same time. There is a new SISO decoder which allows for the updating of the Log-likelihood-ratio's in a single operation, as opposed to the two pass traditionally associated with the Tanner Graph's. In the decoder, there is a mapping structure that correctly aligns the stored estimates, the stored differences and the SISO's. There is also the ability to deal with multiple instances of the same data being processed at the same time. This structure manages the updates and the differences in such a manner that all calculations on a single piece of data that are processed in parallel are incorporated correctly in the new updated estimates.

The invention discloses a fast tree graph decomposition method for decomposing the TANNER graph corresponding to the quasi-cyclic low density parity check code into the tree graph with expected number, wherein the method includes the steps of: decomposing the basic matrix corresponding to the quasi-cyclic LDPC code according to the set mode, then decomposing the matrix into the tree graph with expected number, thereby decomposing the TANNER graph of the quasi-cyclic LDPC code into the tree graph with expected number. The fast tree graph decomposition method of the invention conveniently performs the tree graph decomposition and the serial decoding to the constructed quasi-cyclic LDPC code, and proves that the number of the ZIGZAG tree graph is less through the simulation, the required iteration times are fewer, the convergence speed is higher, in addition, the invention adopts the less tree graph decomposition method which has the convergence speed two times higher than that of the flood information transfer algorithm.

The invention provides an iterative massage passing (IMP) PN code capturing method based on a sum-product algorithm on the condition of a low signal to noise ratio. According to the method, an m sequence is modelized into a special linear block code; a sum-product decoding algorithm is executed on a Tanner graph to obtain maximum posteriori estimation of the m sequence; and an initial state is selected by introducing a posteriori log-likelihood ratio to generate a local m sequence; and at last, serial correlation verification is carried out with reception data and capturing is completed. The greatest advantage of the method provided in the invention is as follows: maximum posteriori estimation of an m sequence is directly decoded by utilization of a sum-product decoding algorithm and a posteriori log-likelihood ratio is introduced to select an initial state. Besides, the method has advantages of rapid capturing speed, low complexity and excellent performance under a low signal to noise ratio. According to the invention, a fundamental principle on IMP PN code capturing is mainly introduced and then an IMP PN code capturing method based on a sum-product algorithm is provided; and an analysis on a selection process of an initial state of an m sequence is emphasized and a detailed flow chart is provided; at last, a capturing performance and a complexity of the method are analyzed though examples.