# Method for decoding cyclic interference-resistant code

FIELD: communications engineering, possible use in data transmission systems, for remote measurement, remote control, in radio-transmitting equipment of small spacecrafts and for deep space telemetry.

SUBSTANCE: in accordance to the invention, at transmitting side code words are generated by encoding information symbols using cyclic code without usage of synchronizing patterns, parameters of cyclic code are changed depending on level of interference, transferred information is accumulated at receiving side, thus creating a selection, then for phasing by code words limits of code word are determined, supposed length of code word is set, and in set window "sliding" symbol-wise discrete Fourier transformation is performed in Galois field for whole volume of selection being analyzed, while at each step of "sliding" discrete Fourier transformation in Galois field, selection of zero spectral components is performed as well as determining of quantity thereof together with building a function of number of zero spectral components at each step of "sliding" discrete Fourier transformation in Galois field, then decimation of given function is performed with step, equal to supposed length of code word, with building of a function estimate of mathematical expectation of number of zero spectral components, phasing moments reach maximum of mathematical expectation estimation function of number of zero spectral components, with consideration of resulting maximum, code words are selected, and then estimate of mathematical expectation of code word spectrums is performed and parameters of cyclic code are evaluated on basis of resulting code words, and then cyclotomic classes are determined, the generative polynomial of cyclic code is restored and code words are decoded.

EFFECT: increased interference resistance of cyclic code receipt, automatic adaptation of characteristics of transferred signal to interference intensity, increased speed of information transfer and accelerated phasing process during transfer of code words without synchronizing patterns.

4 dwg

The proposed method relates to the field of communication technology and can be used in data transmission systems, and in systems of telemetry, remote control, radio transmitting equipment small satellites and telemetry deep space without the use of synchronously and additional control channel.

There is a method of decoding a cyclic error correcting code (Losev CENTURIES, Brody E.B., cookie monster VI Search and decoding of complex discrete signals, Ed. Vigorita. - M.: Radio and communication, 1988, str), wherein at the receiving side calculates the syndrome of the error correcting code. Upon detection of an undistorted error-correcting code that is determined by a zero syndrome, decide on the admission of error-correcting code and then allocate the information part of the error correcting code.

This method has low immunity due to the low probability of correct synchronization and the fact that the decoding of error-correcting code performs only error detection without correction.

There is also known a method of decoding a cyclic error correcting code (Bolkhovitin L.M., Gurkin S. p., Kvashennikov CENTURIES, Sosin P.A. transfer of the formalized messages self-synchronizing code with variable parameters. Technology communications, vol. TPS, VIP, 1990,p.39), where on the transmission side to form the output sequence representing the sum modulo two of cyclic error-correcting code and a synchronization sequence at the receiving side, the sequence is multiplied by the check polynomial error-correcting code and calculate the synchronization sequence. Upon detection of a certain combination of synchronizing sequence take the decision on whether frame synchronization and then allocate the information part of the error correcting code.

However, this method has low immunity due to the fact that decoding of error-correcting code performs only error detection without correction.

There is also known a method of decoding a cyclic error correcting code (Beck, GV, Bogdanovich V.N., Kireev OP Method of synchronization messages. Sat.: Construction and analysis of communication systems. M.: Nauka, 1980, p.84), namely, that on the transmission side to form the output sequence representing the sum modulo two of cyclic error-correcting code and the synchronizing sequence. At the receiving side adopted the first sequence is multiplied by the check polynomial error-correcting code and calculate the clock on sledovatelnot. Next, carry out the detection of a particular combination synchronizing sequence with accounting errors imposed on the accepted sequence in the communication channel. Upon detection of the synchronization sequence shall take the decision on whether frame synchronization and produce error-correcting code. Then determine the combination of errors and perform error correction in the error correcting code.

The disadvantage of this method is also low immunity, because the message is only possible if the code word errors, the multiplicity of which is not above correcting ability of the code.

Known methods of decoding of cyclic codes (RF patents №№2231216 C2, 2109407 C1, 2024053 C1).

Known methods closest to the present invention is a Method of decoding a cyclic error correcting code (patent RF №2231216 C2), which is selected as a prototype. This method provides increased robustness of reception due to the fact that on the transmission side output sequence recurrently continue using test ratio of cyclic error-correcting code on the receiving side additionally carry out decoding of cyclic extensions of the received sequence. While decoding implementation of tlaut in the sliding receive window and outside sliding window, permit the occurrence of any number of errors in the received sequence, including exceeding the correction capability of error-correcting code, but does not lead to the transformation of the code.

However, using this method requires the presence of the synchronization symbols and the parameters of the correction code remain constant regardless of the jamming environment, which reduces the transmission speed and increase the power transmitting apparatus. Reducing energy consumption is an important task when using small satellites and spacecraft deep space.

An object of the invention is to increase the speed of data transfer by simultaneously reducing the energy consumption of radio transmitting equipment in the communication channels with interference.

The problem is solved according to the method of decoding of cyclic error-correcting code, namely, that on the transmission side to form the output sequence representing the sum modulo two of cyclic error-correcting code and a synchronization sequence, recurrently continue using test ratio of cyclic error-correcting code at the receiving side additionally carry out decoding of cyclic extensions of the received sequence, different those who, that on the transmission side to form code words by encoding the information symbols using a cyclic code without using synchronously, change the parameters of the cyclic code depending on the level of interference at the receiving side perform the accumulation of the transferred information, forming thereby a sample, then for phasing the code words define the boundaries of the code word are expected length of the code word and the given window have a "moving" character of the discrete Fourier transform in the Galois field throughout the volume of the analyzed sample, at each step of the "moving" of the discrete Fourier transform in the Galois field perform allocations zero spectral component and the determination of their the number of building function of the number zero spectral component at each step of the "moving" of the discrete Fourier transform in the Galois field, then perform decimate this function increments the expected length of the code words, with the construction of the evaluation function the mathematical expectation of the number zero spectral component, moments phasing reach the maximum evaluation function the mathematical expectation of the number zero spectral component, based on the obtained maximum allocate a code word, then determine the grade for Mathematica is anyone out items spectra of code words and estimate the parameters of the cyclic code according to the received code words, next, define the cyclotomic classes, restore the generating polynomial of the cyclic code and perform the decoding code words.

Consider the implementation of the proposed method of decoding cyclic error-correcting code.

On the transmission side form the output sequence. To do this, the original message volume k symbols of the first code cyclic error-correcting code. A coding information get the word cyclic code C(n,k)=x_{0}x_{1}, ..., x_{n-1}where k is the number of information symbols, n is the length of the codeword of a cyclic code. Since the code is cyclic, there is a recurrence relation, which receive all control characters code x_{k+i}=f(x_{i}x_{1+i}, ..., x_{k-1+i}) where i=0...n-k-1. In this case before the data are assessing the jamming environment and accordingly determine the parameters of error-correcting code. Received code words are transmitted in the communication channel.

At the receiving side perform the accumulation of the transferred information, forming thereby a sampling of L. For phasing the code words, i.e. the definition of the boundaries and the length of the code word are expected length of the code word n and the given window have a "moving" character DPPG on which this volume of the analyzed sample:

At each step of the "moving" DPFG perform allocations zero spectral component and determine their numberwhere N_{0}(s) is the value function of the number of zero elements in s-m-step. The graph of a function of N_{0}(s) when "sliding" DPFG for cyclic code (63,57) is depicted in figure 1 (further graphical material is presented for cyclic code (63,57)).

Next, analyze the functions of N_{0}the number of null elements of the spectrum. Set the size of the analyzed window, equal to the expected length of the code word is n or greater. Assess the mathematical expectation of the number of null elements of this function, using the expressionwhere N- the number of analyzed samples (length of the "window" of the alleged code words).

When adequate synchronization functionevaluation of the mathematical expectation of the number zero spectral elements will be presented on figure 2.

In moments the correct phasing will be highs. If the analysis of a function of N_{0}the number of null elements of the spectrum was taken, the window size is equal to the expected length of the code words is,
n, then the graph of the functionevaluation of the mathematical expectation of the number zero spectral elements will have one maximum. If the maximum of this function is not observed, it is necessary to change the length of the estimated code word and to carry out the construction of a function of N_{0}and then.

If the analyzed digital stream spoziroval, i.e. starts with a code word, then the graph of the functionwill be presented on figure 2. If the stream is not spoziroval, then the graph of the functionwill be presented on figure 3.

If the analysis of N_{0}the number of null elements of the spectrum was taken as the window size, two or more times the length of the code word is n, then the graph of the functionevaluation of the mathematical expectation of the number zero spectral elements will be correspondingly two or more maxima of the function, and the period of repetition is equal to the length of the code word n.

If thewill have a maximum, greater or equal to the threshold value, deciding that the detected encoded signal is a cyclic code. The threshold value is determined by the length of the analyzed is th at a discrete Fourier transform in the Galois field of the window. Thus, the phasing method of successive shifts, based on the difference of the synchronous state of the receiver from asynchronous, where the synchronous refers to a state in which only accepts code words (excluding the effect of errors in the line).

After the detection of the encoding, and hence, determine the length of the code word and phasing occurs, the task of determining the structure and parameters of the encoder. For this above code words carry DPFG.

Determine the estimate of the mathematical expectationelements of the spectrum of F(x)

The distribution schedule of the evaluation of the expectationelements of the spectrum presented in figure 4.

As can be seen from the graphs, if the signal is accepted without interference estimate the mathematical expectationelements of the spectrum characterizing the generating polynomials of encoders is equal to 0. In the case of interference in the communication channel values of the spectral components, characterizing the roots of the generating polynomial, which must be equal to 0 will be non-0. The analysis showed that the use of statistical estimates of the expectation values of the spectral components allows to provide ve is aatest identification 0,99 error in the communication channel to 10^{
-3}. Then carry out the determination of the cyclotomic classeswith the subsequent recovery of the generating polynomial encoderwhere α^{i}is a primitive element of GF^{(n)}(q) of degree i, where. Set To equal to the Union of cyclotomic classes.

Depending on the settings of the encoder code word will be showing the structure of the encoder cyclotomic class modulo n=p^{m}-1 zero spectral components.

Thus, the proposed method is compared with the prototype not only provides increased robustness of receiving the codeword of a cyclic code, but also allows you to speed up the process of phasing in the transmission of code words without the use of synchronization symbols. Used the sign for phasing of code words is the same for different classes of codes. Due to the fact that there is no need in characters synchronously, you can increase the speed of information transmission. Thus, you can dynamically modify the characteristics and parameters of the encoder of the transmitting apparatus of the ICA and the SPACECRAFT deep space without using a separate control channel by increasing the speed and reducing energy satr the t for the transmission of information.

The method of decoding of cyclic error-correcting code, namely, that on the transmission side to form the output sequence representing the sum modulo two of cyclic error-correcting code and a synchronization sequence, recurrently continue using test ratio of cyclic error-correcting code at the receiving side additionally carry out decoding of cyclic extensions of the received sequence, characterized in that on the transmission side to form code words by encoding the information symbols using a cyclic code without using synchronously, change the parameters of the cyclic code depending on the level of interference at the receiving side perform the accumulation of the transferred information, forming thereby a sample, then for phasing the code words define the boundaries of the code word are expected length of the code word and the given window have a "moving" character of the discrete Fourier transform in the Galois field throughout the volume of the analyzed sample, at each step of the "moving" of the discrete Fourier transform in the Galois field perform allocations zero spectral component and the determination of their quantity, the building features a number of the STV zero spectral component at each step of the "moving" of the discrete Fourier transform in the Galois field, then perform decimate this function increments the expected length of the code words, with the construction of the evaluation function the mathematical expectation of the number zero spectral component, in moments of phasing reach the maximum evaluation function the mathematical expectation of the number zero spectral component, based on the obtained maximum allocate a code word, then determine the estimate of the mathematical expectation of items spectra of code words and estimate the parameters of the cyclic code according to the received code words, then define the cyclotomic classes, restore the generating polynomial of the cyclic code and perform the decoding code words.

**Same patents:**

FIELD: communications engineering, in particular, engineering of data transfer systems for decoding cyclic interference-resistant codes without preliminary phasing.

SUBSTANCE: during decoding of cyclic interference-resistant code, range of presumed lengths of code combinations [n_{min}-n_{max}] is determined, and assumed phase of beginning of code combination f is set, from phase f in received code series several presumed code combinations S_{i} are selected and pairs are formed from selected combinations in accordance to condition S_{i}≠S_{k}, N of greatest common divisors, represented by polynomials, is calculated, and from calculated polynomials a polynomial of least order is selected, which is considered equal to original polynomial g(x) of cyclic interference-resistant code, if N of greatest common divisors is equal to "1", then length of proposed code combination n is increased by one, phase of proposed beginning of code combination is altered for one, if greatest common divisor, different from "1", is not found for all n∈[n_{min}-n_{max}], combinations of errors are determined in code word and selected code combinations are decoded.

EFFECT: development of method for decoding cyclic interference-resistant code under conditions of adaptation of interference-resistant code to quality of information transfer channel.

3 cl

FIELD: communications engineering; data transfer, telemetering, and telecontrol systems.

SUBSTANCE: proposed codec has on sending end code-word data part shaper whose output and that of code-word synchronizing part shaper are connected to modulo two adder input; on receiving end it has binary filter whose code-word data part shaper output is connected to accumulator connected to synchronizing sequence decoder and to error connection unit whose outputs are connected to respective inverting inputs of code-word data part shaper; output of the latter functions as data output of device; output of binary-filter code-word synchronizing part is connected through switching unit to input of code-word data part shaping unit; synchronizing sequence decoder output is connected to control input of switching unit and to error correction unit input; on receiving end accumulator outputs are connected to inputs of code-word data part shift decoder whose output is connected to input of delay circuit whose output functions as second control input of switching unit and as synchronizing output of device.

EFFECT: enhanced noise immunity.

1 cl, 1 dwg

FIELD: communications engineering; network remote measuring and control systems.

SUBSTANCE: proposed noise-immune cyclic code codec designed for data transfer without pre-phasing has on sending end code-word information section shaper incorporating shift-register memory elements, units for computing verifying parts of noise-immune code of code-word information section, and modulo two adder of code-word information section shaper; code-word synchronizing section shaper and modulo two adder of code-word synchronizing section; on receiving end it has binary filter incorporating binary-filter shift register memory elements, computing units for verifying parts of binary-filter noise-immune code, and binary-filter modulo two adder; shift register of code word information section; decoder; accumulator; error correction unit; unit for shaping synchronizing section of code word; and modulo two adder units.

EFFECT: enhanced speed of device.

1 cl, 1 dwg

FIELD: data encoding methods.

SUBSTANCE: proposed method for encoding sparse parity control code formed from information-section matrix and from parity-section matrix includes steps of information-section matrix conversion into array code structure and assignment of exponent sequences to each column of sub-matrix; extension of two-diagonal matrix corresponding to parity-section matrix so that amount of displacement between diagonals were of random value; enhancement of normalized two-diagonal matrix; evaluation of degree of displacement for cyclic shift of columns in each sub-matrix of higher normalized two-diagonal matrix; and definition of parity symbol corresponding to column in parity control matrix.

EFFECT: enhanced encoding efficiency.

9 cl, 25 dwg, 5 tbl

FIELD: electrical communications; digital data transfer systems for decoding noise-immune variable-length concatenated code.

SUBSTANCE: proposed decoding device for noise-immune variable-length concatenated code has buffer memory and frame synchronization unit; their inputs are integrated to function as information input of device; outputs of buffer memory and frame synchronization unit are connected to internal-code decoder whose output is connected to external-code decoder; output of the latter functions as information output of device; newly introduced in device are time interval shaper, code word counter, and analysis unit; synchronization input of device is connected to input of time interval shaper whose control input is connected to output of frame synchronization unit; output of time interval shaper is coupled with inputs of code word counter and analysis unit whose other input is connected to output of code word counter whose synchronization input is coupled with internal-code decoder; output of analysis unit is connected to external-code decoder.

EFFECT: enhanced noise immunity of decoding device.

1 cl, 1 dwg

FIELD: mobile communication systems for burst data transfer including transfer of control data for hybrid automatic retransmission request.

SUBSTANCE: absolute six-bit grant pointing to admissible maximal data transfer speed is generated for transmitting burst data of ascending communication line and sixteen-bit control of cyclic redundancy code referred to user equipment identifier is conducted by combining cyclic redundancy code control with user equipment identifier. Cyclic redundancy code referred to user equipment identifier and eight tail bits are added to six-bit absolute grant and summed-up bits are encoded at code speed of 1/3. Nineteen resultant encoded bits are coordinated with respect to speed in compliance with predetermined combination for coordinating speed of (1, 2, 5, 6, 7, 11, 12, 14, 15, 17, 23, 24, 31, 37, 44, 47, 61, 63, 64, 71, 72, 75, 7780, 83, 8485, 87, 88, 90) and transferred to user equipment.

EFFECT: enhanced reliability of control information transfer.

16 cl, 5 dwg

FIELD: the invention refers to the field of radio liaison particularly to arrangements and modes for definition of logarithmic likelihood ratio for turbo codes and the metrics of embranchment for convolutional codes at using preliminary coding.

SUBSTANCE: the technical result is reduction of the effect of multiplication of errors achieved because multitude of signal elements is received. At that the signal element contains the totality of modulation symbols out of the totality of coded bits, the first subset of signal elements for which the bit has the first meaning and the second subset of signal elements for which the bit has the second meaning are defined. At that the first and the second subsets are signal elements out of an extended signal group. The probability that the bit equals the first meaning or the second meaning depending from the received signal element is defined, then the symbol of flexible decision of possibility that the bit equals the first meaning or the second meaning is defined. At that the symbols of flexible decision may be represented by the logarithmical likelihood ratios.

EFFECT: reduces effect of multiplication of errors.

38 cl, 7 dwg

FIELD: radio engineering; transferring voice information in digital radio communication systems.

SUBSTANCE: in order to convert information word into code characters of various concatenated cascades, data bursts are formed on sending end, each burst incorporating information character sequence; information character sequence is supplemented in each data burst with sum of cyclic redundancy check CRC; intermediate code sequence is formed for which purpose information sequence of each data burst supplemented with CRC sum is encoded by recursive convolution code incorporating time-dependent rational transfer function without introducing redundancy, and lattice diagram of non-recursive rational transfer function code is formed; assigned code characters are added to intermediate code sequence formed earlier and encoded by recursive convolution code so as to ensure that the only final node were known at desired depth.

EFFECT: enhanced radio communication quality.

2 cl, 12 dwg

FIELD: module for generating decoding integration circuits for use in particular in turbo-devices and for generation of folding coding circuits.

SUBSTANCE: module is parametric and, due to that, makes it possible to generate decoding circuits, having various working characteristic, which may be used in turbo-devices, using various decoding modes and various architectures. Also, module ensures generation of decoding circuits, which are special because of capacity for selective control over a set of generator polynomials and, therefore, may be used in asymmetric turbo-devices.

EFFECT: ensured generation of decoding circuits with various working characteristics with usage of various decoding modes and various technologies.

2 cl, 7 dwg, 1 tbl

FIELD: computer engineering, possible use in combination devices, and also devices for storing and transferring information.

SUBSTANCE: device contains original circuit, four groups of AND elements, group of OR elements, encoding device, folding circuit, register, error syndrome circuit, checks circuit, three decoders, corrector.

EFFECT: decreased number of controlling discharges.

1 dwg, 1 app

FIELD: computer engineering, possible use in combination devices, and also in devices for storing and transferring information.

SUBSTANCE: device contains memorizing device, four groups of AND elements, AND element, group of OR elements, seven OR elements, encoding device, register, error syndrome circuit, NOT element, decoder, inversion block, even parity check circuit, corrector.

EFFECT: increased trustworthiness of device operation.

1 dwg, 1 app

FIELD: computer engineering, possible use in combination devices, and also in devices for storing and transferring information.

SUBSTANCE: device contains memorizing device, four groups of AND elements, AND element, group of OR elements, seven OR elements, encoding device, register, error syndrome circuit, NOT element, inversion block, decoder, even parity check circuit, corrector.

EFFECT: increased trustworthiness of device operation.

1 dwg, 1 app

FIELD: computer engineering, possible use in combination devices, and also in devices for storing and transferring information.

SUBSTANCE: device contains original circuit, four groups of AND elements, AND element, group of OR elements, seven OR elements, encoding device, register, error syndrome circuit, NOT element, decoder, corrector.

EFFECT: increased trustworthiness of device operation.

1 dwg, 1 app

FIELD: Witterby algorithm applications.

SUBSTANCE: system has first memory element for storing metrics of basic states, multiplexer, capable of selection between first and second operating routes on basis of even and odd time step, adding/comparing/selecting mechanism, which calculates metrics of end states for each state metric. Second memory element, connected to adding/comparing/selecting mechanism and multiplexer is used for temporary storage of end states metrics. Multiplexer selects first operating route during even time steps and provides basic states metrics, extracted from first memory element, to said mechanism to form end state metrics. During odd cycles multiplexer picks second operating route for access to second memory element and use of previously calculated end state metrics as metrics of intermediate source states.

EFFECT: higher efficiency.

2 cl, 9 dwg

**FIELD: communications engineering.**

**SUBSTANCE: proposed device and method for mobile code-division multiple access communication system including device for transferring channel of backward-link transmission speed indicator afford generation of optimal code words ensuring optimal coding for all types of coding procedures from optimal type (24.1) up to optimal coding procedure 24.7 and supporting all optimal-coding devices.**

**EFFECT: optimized capacity.**

**74 cl, 21 dwg, 44 tbl**

FIELD: communications engineering; network remote measuring and control systems.

SUBSTANCE: proposed noise-immune cyclic code codec designed for data transfer without pre-phasing has on sending end code-word information section shaper incorporating shift-register memory elements, units for computing verifying parts of noise-immune code of code-word information section, and modulo two adder of code-word information section shaper; code-word synchronizing section shaper and modulo two adder of code-word synchronizing section; on receiving end it has binary filter incorporating binary-filter shift register memory elements, computing units for verifying parts of binary-filter noise-immune code, and binary-filter modulo two adder; shift register of code word information section; decoder; accumulator; error correction unit; unit for shaping synchronizing section of code word; and modulo two adder units.

EFFECT: enhanced speed of device.

1 cl, 1 dwg

FIELD: communications engineering; network remote measuring and control systems.

SUBSTANCE: proposed noise-immune cyclic code codec designed for data transfer without pre-phasing has on sending end code-word information section shaper incorporating shift-register memory elements, units for computing verifying parts of noise-immune code of code-word information section, and modulo two adder of code-word information section shaper; code-word synchronizing section shaper and modulo two adder of code-word synchronizing section; on receiving end it has binary filter incorporating binary-filter shift register memory elements, computing units for verifying parts of binary-filter noise-immune code, and binary-filter modulo two adder; shift register of code word information section; decoder; accumulator; error correction unit; unit for shaping synchronizing section of code word; and modulo two adder units.

EFFECT: enhanced speed of device.

1 cl, 1 dwg

FIELD: communication systems.

SUBSTANCE: method includes generating sets of sub-codes of quasi-additional turbo-codes with given encoding speeds, and given sub-codes are reorganized as a set of sub-codes with another encoding speed for use in next transfer of sub-code with given encoding speed.

EFFECT: higher efficiency.

9 cl, 13 dwg

FIELD: data transfer technologies.

SUBSTANCE: method includes segmentation of length N of quasi-complementary turbo-codes on preset amount of sections, determining identifiers of sub-code packets appropriate for segmented portions, setting of said packets separated for initial transfer of sub-code, calculation of number of remaining symbols in form N-Fs, where N - length of quasi-complementary turbo-codes, and Fs - position of start symbol of sub-code of quasi-complementary turbo-codes, determining position of symbol of remaining symbols in amount equal to sub-codes amount, which have to be sent and serial transfer of sub-code symbols from position of starting symbol Fs to position of last symbol Ls.

EFFECT: higher efficiency.

5 cl, 17 dwg