18 results about "Error floor" patented technology

The invention relates to a coding method, a decoding method and a device, in the coding method, first equipment can determine a second bit sequence and a third bit sequence based on a first bit sequence, and the third bit sequence comprises a bit sequence of which the weight is higher than a first threshold in a base graph corresponding to the first bit sequence. That is, the weight corresponding to the second bit sequence is lower than the weight corresponding to the third bit sequence. Furthermore, the first device can perform polar code coding on the second bit sequence, which is equivalent to providing additional protection for the second bit sequence with lower weight in a polar code coding mode, so as to improve the error correction performance. And for the third bit sequence with relatively high weight, LDPC coding can be performed on the third bit sequence and a polarization code coding result (namely, a fourth bit sequence obtained by performing polarization code coding on the second bit sequence). The error floor of LDPC decoding is reduced, and the error correction performance of LDPC codes is improved.

The invention discloses an LDPC code check matrix construction method and device, and the method comprises the steps: constructing an initial basis matrix based on a finite field, determining a girth extension matrix based on a density evolutionary algorithm and an LDPC code construction algorithm, carrying out the multiplication and superposition of the initial basis matrix and the girth extension matrix, and determining a candidate check matrix. By multiplying and superposing the two matrixes, the distribution of non-zero elements in the initial basis matrix can be improved, so that the sparsity of the initial basis matrix is stronger, and the breaking of short rings and the expansion of girth in the initial basis matrix are realized. And finally, for each element in the candidate check matrix, performing matrix hash extension on the element according to the element value of the element, and determining the LDPC code check matrix. The design of high-performance medium-short codes and ultra-long QC-LDPC codes is realized, and the error code flat layer is reduced while the rapid convergence of the waterfall region is ensured.

This application discloses a method, device, medium, and product for constructing a check matrix for QC-LDPC codes, relating to the field of channel coding technology. The method comprises: first, generating an initial check matrix without four loops; second, based on pre-decoding, screening target columns that are prone to decoding oscillation, eliminating the non-zero entries with the largest number of six loops to generate an intermediate check matrix; and finally, optimizing the six-loop distribution of the intermediate matrix column by column to generate a target check matrix with mixed column weights. This application addresses the decoding error floor problem caused by short loops (four loops, six loops) in high-rate, long-codeword QC-LDPC codes. By dynamically optimizing the check matrix structure through a three-step construction method, the method significantly reduces the number of harmful short loops in the check matrix, improving decoding performance, and reducing error floor.

A modified version of the min-sum algorithm (“MSA”) which can lower the error floor performance of quantized LDPC decoders. A threshold attenuated min-sum algorithm (“TAMSA”) and / or threshold offset min-sum algorithm (“TOMSA”), which selectively attenuates or offsets a check node log-likelihood ratio (“LLR”) if the check node receives any variable node LLR with magnitude below a predetermined threshold, while allowing a check node LLR to reach the maximum quantizer level if all the variable node LLRs received by the check node have magnitude greater than the threshold. Embodiments of the present invention can provide desirable results even without knowledge of the location, type, or multiplicity of such objects and can be implemented with only a minor modification to existing decoder hardware.

The invention discloses a code rate adaptive data coordination method suitable for continuous variable quantum key distribution, and belongs to the technical field of continuous variable quantum key distribution. Aiming at the problem that the existing method cannot realize stable and efficient extraction of a key in a key distribution system, high coordination efficiency under a specific code rate is realized by using a protograph LDPC code, and then code rate compatibility is realized through a specific matrix puncturing technology, so that an error floor is effectively reduced, and the key distribution efficiency is improved. And stable and efficient data coordination is realized in a relatively large signal-to-noise ratio range. Through simulation tests, the self-adaptive range of the signal-to-noise ratio is 0.028-0.252, the coordination efficiency can reach more than 95%, the average frame error rate is about 30%, the robustness of the system is effectively improved, and the application of the continuous variable quantum key distribution technology in actual scenes is promoted.

The application provides a joint coding method and device under a relay channel model, a storage medium, and an apparatus. The method adjusts a sending scheme according to the characteristics of a joint coding matrix, increases original bit information, reduces compressed bit information, and reduces the error floor level of the overall system. The decoding and forwarding of the relay node provides the compressed bit information reduced in the sending node, so that the destination node can have more information for decoding, and the performance of the waterfall region of the system is improved. In the case that the total energy of the sending node and the relay node is constant, the optimal adaptive joint coding sending strategy is selected by optimizing different energy allocation conditions. The scheme uses the same joint coding matrix in the sending node, the relay node, and the destination node, does not increase the complexity of coding and decoding, and has the characteristics of low complexity.

The present application provides a coding method and a communication apparatus. A sub-matrix of a core check region of a base graph of LDPC is designed, such that the sub-matrix of the core check region meets certain characteristics, and the minimum cycle length of the base graph corresponding to the core check region can be increased to the maximum value, thereby preventing the problem whereby when a core check sub-matrix of a base graph uses an IRA structure, numerous small-scale trapping sets are present and error floors are likely to occur at a plurality of lifting values. In addition, for the design of a core check sub-matrix, a corresponding coding method is further provided, so as to reduce the coding complexity when the core check sub-matrix provided in the present application is applied to coding.

The invention discloses an engineering machinery communication data encryption method and system based on QC-LDPC (Quasi-Cyclic Low Density Parity Check), and the method comprises the steps: firstly carrying out the encryption processing of obtained communication data of an engineering machinery vehicle through an AES (Advanced Encryption Standard) encryption technology, so as to improve the safety of the data; secondly, encoding the encrypted data through a QC-LDPC encoding technology, and further improving the reliability of the data by utilizing the advantages of low encoding complexity, low storage requirement, friendly hardware implementation, high code length flexibility, low error floor and the like of the QC-LDPC encoding technology; and finally, noise is added on the coded data to ensure that the data transmitted to the receiving end is wrong data under different channels, so that the security of the communication data is further protected.

The present application provides an encoding or decoding method and a communication apparatus. A base matrix applied to LDPC provided in the method is different from a base matrix in an existing solution. Compared with two columns in the base matrix in the existing solution that have a relatively large absolute value of the difference between column weights, in the design of the base matrix provided in the present application, the two columns have more regular column weights. In addition, elements of the two columns in a row region other than a given row region are the same. When the two columns are from a column region of the base matrix that satisfies corresponding characteristics, and the given row region is from a row region of the base matrix that satisfies corresponding characteristics, the base matrix can generally reduce the error floor under the application of different code lengths and code rates in a wireless system, so that the base matrix can be applied to a high-reliability communication scenario.

The application discloses a method for constructing QC-LDPC code with low error floor. The method comprises the following steps: firstly, selecting random number filling matrix elements to generate an index matrix of QC-LDPC code according to an original graph, and performing girth optimization on the index matrix to minimize the number of loops with a specified degree in a Tanner graph corresponding to the matrix; and then, searching for harmful trap sets in the matrix by column through decoding simulation, and eliminating the harmful trap sets by changing the shift value of the matrix elements until all harmful trap sets with a specified size are eliminated. The method has the following advantages: firstly, the method has no special requirements on the parameters of the QC-LDPC code matrix, and supports the design of flexible code rate. Secondly, the method searches for and eliminates the harmful trap sets in the QC-LDPC code, and takes into account the optimization of the minimum girth of the code, so that the constructed QC-LDPC code has good error floor performance. The construction method disclosed by the application can generate QC-LDPC code with uncorrectable error rate lower than 10 ‑15 , and is suitable for occasions with high requirements on error correction performance, such as flash memories.

This disclosure describes techniques regarding improving the decoding performance of a code word, such as an LDPC code word. In an example, the error correction capability of a decoding layer is improved, where the improvement can include lowering the error floor. To this end, high order information is used in the decoding. High order information refers to information used during the decoding of a variable node that has an error, which is not limited to that variable node and the check nodes connected to it, but includes information about variable nodes that also have an error and are connected to the variable node via satisfied check nodes, and about unsatisfied check nodes connected to these variable nodes.

A regular variable node degree fountain coding method first constructs a coding node symbol degree distribution function, accelerates the decoding process by increasing the probability of occurrence of small degree value coding symbols, and generates a degree value according to the degree distribution function; then, based on the information symbol selection probability, selects the original information symbol to participate in this encoding, and splices the degree information field with the coding information field to construct a transmission data packet; secondly, by recording the number of times all original information nodes participate in the encoding, the information node selection probability is updated; finally, the received data is decoded at the destination node using a belief propagation algorithm. The present invention optimizes the coding node degree distribution function, increases the probability of occurrence of small degree value coding symbols, adopts an information node selection strategy based on the number of coding participations, realizes the regularization of symbol variable node degree values, selects information nodes with small degree values during encoding, achieves the purpose of reducing the error platform and saving decoding overhead during the fountain coding process, and reduces the coding complexity at the source node.

This disclosure relates to techniques related to improving error floor performance of a belief flip (BF) decoder. In some examples, the error floor performance is improved by determining a set of unreliable check nodes (CNs) and using information about the set of unreliable CNs to compute flip energies of variable nodes (VNs). In this way, flip energies can be more accurately computed, thereby reducing the error floor. The set of unreliable CNs can be constructed by applying various criteria, such as criteria related to path length to unsatisfied CNs, degree of VNs in paths to unsatisfied CNs, and / or check sum values. Path length and VN degree can be used as selection criteria to determine which CNs qualify to join the set of unreliable CNs. Check sum values can be used as a trigger condition for constructing and / or using the set of unreliable CNs.

The invention provides a coding or decoding method and a communication device. A basis matrix applied to LDPC (Low Density Parity Check) provided in the method is different from a basis matrix in an existing scheme. Compared with two columns with larger absolute values of the difference value of the column weight in the basis matrix of the existing scheme, the column weight of the two columns is more regular in the design of the basis matrix provided by the invention. In addition, the elements of the two columns in other row areas except the given row area are the same. When the two columns are from the column area, meeting the corresponding characteristics, of the basis matrix and the given row area is from the row area, meeting the corresponding characteristics, of the basis matrix, the basis matrix can generally reduce the error floor under the application of different code lengths and code rates of a wireless system, so that the method can be applied to a high-reliability communication scene.

The invention relates to a local decoding method of a coding modulation system adopting a constant weight former, and belongs to the technical field of information theory and coding. The method comprises the following steps: in a low density parity check (LDPC) coding modulation system adopting a constant weight shaper (CCDM), when decoding of an original minimum sum (MS) algorithm fails, performing double expansion on a connection relation of a Tanner graph based on an LDPC code on a check node UCNs which is not satisfied and a CNs connected with a variable node VNs corresponding to an unreliable bit in a CCDM code word; vNs connected with the CNs are selected through double expansion, values of corresponding positions in the original confidence vectors are locally corrected through candidate VNs, and a candidate input information vector list is generated; and re-decoding the vectors in the list one by one to obtain a decoding output result. According to the method disclosed by the invention, the error platform of the LDPC code in the coding modulation system can be reduced without remarkably increasing the calculation complexity, the error diffusion in the inverse forming process of the system is reduced, and the transmission reliability of the LDPC coding modulation system is improved.

The invention provides a joint coding method, device and equipment under a relay channel model and a storage medium, a sending scheme is adjusted at a sending node according to the characteristics of a joint coding matrix, original bit information is increased, compressed bit information is reduced at the same time, and the error leveling level of a whole system is reduced. And meanwhile, reduced compressed bit information is provided at the sending node by utilizing decoding and forwarding of the relay node, so that the destination node can have more information for decoding, and the waterfall zone performance of the system is improved. Under the condition that the total energy of a sending node and a relay node is fixed, the optimal self-adaptive joint coding sending strategy is selected by optimizing different energy distribution conditions. According to the scheme, the same joint coding matrix is used at the sending node, the relay node and the destination node, the coding and decoding complexity is not increased, and the method has the characteristic of low complexity.

Embodiments of the present application provide an encoding method and apparatus and a decoding method and apparatus, which are used for reducing trapping sets in a base matrix, thereby reducing the occurrence of error floors, and facilitating ultra-reliable communication. The encoding method comprises: a first communication apparatus obtains a sequence of bits to be encoded; on the basis of a first base matrix, the first communication apparatus performs LDPC encoding on the sequence of bits to be encoded, and obtains an encoded sequence of bits, wherein the first base matrix comprises a first region, the first region comprises a plurality of columns of sub-matrices, each column of sub-matrices comprises a plurality of sub-matrices, column weights of any two columns of sub-matrices among the plurality of columns of sub-matrices are equal, quantities of any non-zero sub-matrices of each column of sub-matrices among the plurality of columns of sub-matrices that are not a first matrix are the same, and the first matrix is a matrix of which both row weights and column weights are 1; and the first communication apparatus outputs the encoded sequence of bits.

The present application relates to an encoding method and apparatus, and a decoding method and apparatus. In the encoding method, a first device may determine a second bit sequence and a third bit sequence on the basis of a first bit sequence, wherein the third bit sequence comprises a bit sequence, which is in a base graph corresponding to the first bit sequence and has a weight higher than a first threshold, that is, a weight corresponding to the second bit sequence is lower than a weight corresponding to the third bit sequence; further, the first device can perform polar code encoding on the second bit sequence, which is equivalent to providing additional protection for the second bit sequence having a lower weight by means of polar code encoding, so as to improve error correction performance; and the third bit sequence having a higher weight can be subjected to LDPC encoding together with the result (i.e., a fourth bit sequence obtained by performing polar code encoding on the second bit sequence) of polar code encoding. The error floor of LDPC decoding is reduced and the error correction performance of an LDPC code is improved.