RU2700398C1 - Method of transmitting data in a digital radio communication system based on codes with low density of parity checks and a method of interleaving code symbols - Google Patents

Abstract

FIELD: data processing and transmission.

SUBSTANCE: invention relates to means for transmitting data in a digital radio communication system based on codes with low density of parity checks. At the transmitting side, data packets are formed, each of which contains an ordered sequence of information symbols. Each information symbol is repeated a certain number of times, depending on its number in order in a sequence of symbols, forming a sequence of repeated information symbols. Number of repetitions is determined in advance. Interleaving in the sequence of repeated information symbols is performed to obtain diversity of consecutive repeating information symbols and forming a sequence of interleaved repeated information symbols. Interleaved repeated information symbols are divided into groups so that the first verification symbol is obtained by summation over the given module of the initial value of the variable summation with all interleaved repeated information symbols from the first group.

EFFECT: technical result consists in improved efficiency of coding.

6 cl, 8 dwg

Description

The invention relates to the field of coding theory, and in particular to systems for combined coding with error correction and detection in order to increase the efficiency of spectrum use when transmitting data in a digital radio communication system.

The urgent task is not only the correction of errors in channel coding, but also the detection of uncorrected errors and the organization of an automatic repeat request (AZP) in order to correct such errors due to the additional transmission of the minimum possible number of code symbols.

The parallel convolutional turbo code is widely known [Berrou C. Near Shannon limit error - correcting coding and decoding / C. Berrou, A. Glaviex, P. Thitimajshina // IEEE International Communications Conference: Proc. 1993. - Geneva (Switzerland), 1993. - P. 1064-1070], which allowed approaching the potentially achievable characteristics of noise-resistant coding. The method is characterized by the following. An information sequence is fed to the input of the first encoder, the same sequence is fed to the input of the second, but after the interleaver. Thus, statistical independence is achieved, especially with large code block sizes. The iterative approach is that the results of one decoding with a soft output can be used with another decoding, as a priori information. However, the turbo code is not more efficient than the convolutional code decoded by the Viterbi algorithm with a frame size of less than 200 bits.

An analogue of the proposed method is a product of the company Trellis Ware code F-LDPC [Halford, Thomas & Bayram, Metin & Kose, Cenk & M. Chugg, Keith & Polydoros, Andreas. (2008). The F-LDPC Family: High-Performance Flexible Modern Codes for Flexible Radio. 376 - 380. 10.1109 / ISSSTA.2008.75.]. The advantage of this solution is the deep integration of the automatic retransmission request protocol (ADR) with the error-correcting coding algorithm. It is argued that the solution has the most flexible capabilities, a single encoder / decoder core supports 40 code rates (1 / 2–32 / 33) while the permissible frame sizes are 128, 256, 512, ..., 16384 bits. However, for example, for voice data, the frame sizes produced by the vocoder can be 16, 40, 80, 172 bits, so the inability to work with blocks of 20 bits or more is a drawback of the F-LDPC code.

The classic ARQ (ARQ), which in case of erroneous decoding of the frame involves erasing the received data, a complete retransmission of the frame and independent decoding of the newly received frame is not effective, because leads to too much redundant data transfer. Hybrid retransmission is becoming increasingly common [Error Control Coding: Fundamentals and Applications / S. Lin, D. J. Costello, Jr. - NJ: Englewood Cliffs. - 1983. - 603 p.]. The essence of the method is that such a strategy is more effective that provides for error decoding to save the frame data, obtain some additional information from the transmitter, and re-decode the frame using this additional information. If the amount of additional information is less than the volume of the whole frame, then the efficiency of using the communication channel is significantly increased. This approach was investigated by Hagenauer [J. Hagenauer. Rate Compatible Punctured Convolutional Codes (RCPC Codes) and their Applications. // IEEE Trans. Commun. - Vol. 36. - Apr. 1988. - P. 389-400.] And Chase [D. Chase. Code Combining A Maximum Likelihood Decoding Approach for Combining an Arbitrary Number of Noisy Packets. // IEEE Trans. Comm. - Vol. 33. - May 1985. - P. 385393] from different positions.

Consider the classification of the considered schemes AZP (ARQ):

• Hybrid AZP Type 1 (HARQ-1 - Chase summation). This retransmission strategy is characterized in that the same frame is retransmitted.

• Hybrid AZP Type 2 (HARQ-2 - increasing redundancy). This retransmission strategy is characterized in that the number of bits for retransmission is less than in the original frame. A copy for retransmission cannot be decoded on its own.

• Hybrid AZP Type 3 (HARQ-3). A copy for retransmission can be decoded independently. However, the frame for retransmission may differ from the originally transmitted frame, that is, it may be encoded with a different code.

This classification can be summarized as follows:

• Automatic transfer station (ARQ) with full transmission (Type 1 and Type 3 belong to it).

• Automatic transfer circuit (ARQ) with partial transmission (Type 2).

The topic of further research will be a partial transmission - hybrid AZP type 2 (HARQ-2).

Several approaches to the implementation of such a strategy of ARP (ARQ) are possible:

1. Retransmission of part of the previously transmitted code symbols of the frame and their optimal addition to the code symbols stored in the receiver.

2. The use of codes with increasing complexity. In case of erroneous decoding on the transmitting side, new (additional) check symbols are calculated, which are transmitted to the receiver.

In the class of linear block codes, one can especially distinguish a subclass of codes with a low density of parity checks [Gallager R. “Low Density Parity Check Codes” // MIT Press 1963], which is superior in its characteristics to a turbo code. A feature of this code is the presence of a simple graphical model of a decoding algorithm defined as decoding on a graph (Fig. 1). Decoding on a graph should be understood in the sense that the graph defines a partition of the entire code word into shorter codes, and short codes can overlap with each other. Overlapping data can be avoided by repeating overlapping code characters. Different copies of the received code symbol or soft decision on this symbol are included in different code words of the shorter code, and all code words of the short code can be decoded independently. Such a structure can be represented as a bipartite graph, one type of vertices, which is associated with code symbols, and the number of edges outgoing from each vertex corresponds to the number of repetitions of the code symbol (a variable vertex is indicated by a rectangle). Another type of vertices corresponds to short codes, and each vertex is a codeword with the number of code symbols equal to the number of incoming edges (the verification vertex is indicated by a circle). A checksum can be assigned to each test vertex as an indicator of errors in the short code. Variable vertices can only be connected with test vertices, and, conversely, test vertices can only be connected with variable vertices, which allows us to consider the graph as bipartite.

Such a bipartite graph is called the graph of Tanner [Tanner R.M. A Recursive Approach to Low Complexity Codes / R.M. Tanner // IEEE Transaction on Information Theory. - 1981. –Vol. IT27, No. 9. - P. 533547]. In fact, for a linear block code, the Tanner graph is a graphical representation of the verification matrix. Error-free decoding is characterized by the equality to zero of all checksums - code constraints.

Code with a low density of parity checks can be decoded in soft solutions using the message exchange algorithm (Fig. 1). The messaging algorithm [Gallager R. “Low Density Parity Check Codes” // MIT Press 1963] initialize each variable vertex with information about the reliability of reception of each symbol (soft decision) received from the channel.

1. The value of the outgoing message from the variable vertex of equal posterior probability for the code symbol is calculated to take a certain value of the code symbol assigned to this variable vertex for each edge of the bipartite graph.

2. At each test vertex, outgoing messages from those variable vertices with which they are connected by the edge of the bipartite graph and for which they are incoming are modified, modifying each edge with outgoing messages to the test vertex, which are equal to the second set of probabilities for the code symbol to take a certain value .

3. Update the outgoing message to the variable vertex with incoming messages, which are outgoing messages to the verification vertex.

4. Repeat iterations a certain number of times or until code restrictions are met.

. Эта функция является решающей функцией или логарифмом отношения правдоподобия. Функция обладает коммутативностью:The sign of the outgoing message is selected so as to satisfy code constraints. The absolute value of the outgoing message is calculated using the function

. This function is the decisive function or the logarithm of the likelihood ratio. The function has commutativity:

. Наиболее простой известен как алгоритм “min-sum”. Абсолютное значение исходящего сообщения равно минимальному абсолютному значению среди входящих сообщений за исключением сообщения от той вершины, для которого предназначено данное исходящее сообщение:There are several methods for defining a function.

. The simplest is known as the min-sum algorithm. The absolute value of the outgoing message is equal to the minimum absolute value among incoming messages, with the exception of the message from the vertex for which this outgoing message is intended:

состоит в определении функции через функцию

, применяемую в LOG MAP алгоритме [Pietrobon S.S. Implementation and Performance of a Turbo/MAP Decoder / S.S. Pietrobon // International J. of Satellite Communication. – 1998. Vol. 16 (Jan-Feb). – P. 23-46]. Функция может быть задана как:Another method of specifying a function

consists in defining a function through a function

used in the LOG MAP algorithm [Pietrobon SS Implementation and Performance of a Turbo / MAP Decoder / SS Pietrobon // International J. of Satellite Communication. - 1998. Vol. 16 (Jan-Feb). - P. 23-46]. The function can be defined as:

, может быть представлена в виде таблицы.Where is the function

may be presented in tabular form.

определено как:There is a modification of the proposed method, where the additional term

defined as:

Modifications of this algorithm are given in [W.K Leung, W.L Lee, A.Wu, L. Ping, “Efficient implementation technique of LDPC decoder” Electron.Lett .., vol. 37 (20), pp.1231-1232, Sept2001]. This method does not require a table, but leads to some deterioration in performance, but it allows you to reduce the number of operations during decoding.

A known method of decoding on a graph, including the construction of a bipartite graph is known from patent US 4295218 Tanner “Error-correcting coding system”, Oct.13, 1981, G06F 11/10. This method is characterized by the following sequence of actions:

on the transmitting side:

• form data packets, each of which contains an ordered sequence of information symbols;

• determine the subcodes for the sequence of information symbols and for each subcode generate verification characters;

• form a code word by adding test characters to information characters;

on the receiving side:

• form the received correlation responses to each of the transmitted code symbols;

• evaluate the noise parameter of the signal plus noise mixture, which is approximately equal to the standard deviation of the equivalent Gaussian white noise, which approximates the noise in the channel;

• form soft decisions about the adopted code symbols using the obtained estimate of the noise parameter of the signal plus noise mixture;

• share soft decisions on accepted code symbols into decisions on information symbols and decisions on verification symbols;

• form code words for subcodes of the code of the generalized parity check;

• for each soft decision included in each code word of the generalized parity check code, a modified soft solution is formed, which is an outgoing message of the code word of the general parity check code, so that the outgoing message of the code word of the general parity check code is the result functional transformation of the original soft decisions - incoming messages of the code word of the code of a generalized parity check;

• apply the received outgoing messages of the code word of the generalized parity check code to those variable vertices with which the subcodes of the generalized parity check code are connected by the edges of the bipartite graph and form subcodes of the repetition code;

• for each soft decision that is included in each code word of the generalized repetition code, a modified soft solution is formed, which is an outgoing message of the code generalized repetition code, which is the result of a functional transformation over the incoming messages of the code word of the generalized repetition code;

• iteratively repeat the process of exchanging outgoing and incoming messages in such a way that the outgoing message of the code word of the generalized repetition code is the incoming message of the code word of the generalized parity check code, and the outgoing message of the code of the generalized parity check code is the incoming message of the code word of the generalized repetition code, forming each iteration, a sequence of modified soft solutions;

• decoded codewords are formed from a sequence of modified soft decisions;

• Multiply each decoded codeword by a check matrix to obtain an ordered sequence of checksums.

символов, возможно, другого алфавита.However, it should be noted that the used repetition of code symbols can be generalized, that is, instead of repetition, encoding can be used or by mapping one code symbol to different ones

characters, possibly another alphabet.

The operation of determining subcodes can, for example, comprise the following actions:

• each information symbol is repeated a certain number of times, depending on its number in order in the sequence of characters, forming a sequence of repeated information symbols, and the number of repetitions is determined in advance;

• interleave in a sequence of repeated information symbols, achieving sufficient diversity of consecutive repeated information symbols and forming a sequence of interleaved repeated information symbols;

• break the interleaved repeated information symbols into groups in such a way that each group forms a subcode codeword.

The formation of subcodes from the sequence of soft decisions made on the receiving side can be defined as the following sequence of actions:

• repeat soft decisions about information symbols in accordance with the pattern of repeating information symbols;

• repeat soft decisions about check characters at least twice except for the last check character;

• for soft decisions about information symbols, they perform interleaving similar to interleaving on the transmitting side;

• form groups of interleaved soft decisions about information symbols similar to groups of corresponding information symbols on the transmitting side, forming a code word for a subcode of a general parity check.

Application of received outgoing messages to the original repeated sequence can be implemented by performing the following sequence of actions:

• deinterleave the outgoing message of the code word of the generalized parity check code so that each copy of the soft decision on the code symbol is associated with the outgoing message of the code word of the generalized parity code corresponding to the copy of the soft decision about this symbol;

• group outgoing messages of the code word of the generalized parity check subcode with soft decisions about the received code symbols so that each group includes a soft decision about the corresponding code symbol and outgoing messages of the code word of the general parity code corresponding to the copy of the soft decision about this symbol, thus forming the code word of the generalized repetition code, putting each codeword of the generalized repetition code in accordance with the code symbol, so that each outgoing A generalized parity check codeword message is an incoming codeword of a generalized repetition code.

Thus, operations on the Tanner graph, which is a graphical model of breaking code into subcodes, can be described as repetition, interleaving, grouping, and repetition, grouping patterns, and the interleaving rule uniquely define a bipartite graph.

So turbo codes are more convenient to describe in terms of repetition and interleaving, and codes with a low density of parity checks in the form of a bipartite graph.

Considering the example with a linear block code, where the short code is a parity check or addition of all code symbols modulo 2, we will call the applied short code on a graph a general parity check, which will consist of summing all code symbols in the Galois field or summing numbers for a given module. If there are no errors during the transmission process, then all such checksums must be equal to zero.

However, if the code is systematic and can be divided into verification and information components, the following drawback is inherent in the above method. If there is a decoding error only in the verification part of the codeword and there are no errors in the information part, the frame will still be marked as erroneous and deleted, and the CRC checksum allows you to control errors only in the information component of the codeword.

Following the terminology from [P. Cameron, J. Van Lint “Graph theory coding theory and flowcharts” // M. Science 1980], we define a path on a graph as a sequence of vertices in which neighboring vertices are adjacent. A cycle is a path where the start and end points coincide. A graph is connected if there is a path between any two vertices, and the distance metric between the two vertices is the length of the shortest path between them. The diameter of the graph is the largest value of the distance between any two vertices in the graph, and the circumference of the graph is the length of the shortest cycle without repeating edges, provided that such a cycle exists. The valency of a vertex is the number of edges emanating from this vertex or the number of vertices adjacent to a given one. If all vertices of the graph have the same valency, then the graph will be called regular. By the chromatic number of a graph we mean the least number of colors into which all edges of the graph can be colored in such a way that any two edges having a common vertex are painted in different colors. A Hamiltonian path or a Hamiltonian cycle will be called a closed cycle, without repeating edges, passing through all the vertices of the graph only once.

The graph must have a girth of at least 4 for use in the considered Tanner decoding method. As an example in FIG. Figure 2 shows the code built on a Peterson graph with a diameter of 6 and a circumference of 10. However, the drawback of this approach is the limited number of vertices in such well-known graphs, as well as the difficulty of constructing graphs containing more than 100 vertices with the specified properties. The decoding efficiency of a graph primarily depends on the structure of the graph, namely, the presence of defects in the graph in the form of structures, resulting in low-weight codewords. One of these defects is the “stopping set” [Tom Richardson y Rudiger Urbanke “The Capacity of Low-Density Parity-Check Codes under Message-Passing Decoding” // March 9, 2001], as well as loops or loops [David MacKay, Good Error-Correcting Codes Based on Very Sparse Matrices // IEEE Transaction on information theory, Vol 45, march 1999], where the “stopping set” is a subset of test vertices for which there are no variable vertices connected by a single edge to any of Verification vertices included in this subset. The set of variable vertices connected to the stopping subset contains the most likely combinations of errors. However, as noted above, a graph can be specified by separately specifying the repetition and grouping pattern, as well as the interleaving law. Moreover, assuming perfect interleaving, optimized repetition-grouping patterns are obtained that are based on uneven repetition [H. Jin, A. Khandekar and RJ McEliece, “Irregular repeat-accumulate codes," Proceedings of the Second International Symposium on Turbo Codes and Related Topics, pp. 18, Brest, France, September 2000], [Thomas J. Richardson and Rüdiger L Urbanke. Efficient Encoding of Low-Density Parity Check Codes]. In this regard, the urgent task is to develop an interleaver separately, which allows to construct a bipartite graph containing the least number of defects using well-known optimized repetition-grouping patterns.

Currently, the class of “turbo-like” codes is widely known, among which are the codes with “repetition-accumulation” known from [H. Jin, A. Khandekar and RJ McEliece, “Irregular repeat-accumulate codes," Proceedings of the Second International Symposium on Turbo Codes and Related Topics, pp. 1-8, Brest, France, September 2000]. “Repeat - by accumulation ”is carried out in the following order: repetition of each information symbol, interleaving of repeated characters, accumulation of the sum modulo 2 interleaved characters. These codes have the properties of both turbo codes and codes with a low density of parity checks and can be decoded in parallel mode - the messaging algorithm, and in serial mode - MAP algorithm. It should be noted that in the latter case, the algorithm is essentially hybrid, consisting of a MAP algorithm for decoding a convolutional code with two states and a message exchange algorithm with unevenly repeated information symbols [J. Li, Low-Complexity, Capacity-Approaching Coding Schemes : Design, Analysis and Applications, Ph.D. dissertation, Texas A&M University, 2002.]. From [H. Jin, A. Khandekar and RJ McEliece, “Irregular repeat-accumulate codes,“ Proceedings of the Second International Symposium on Turbo Codes and Related Topics, pp. 1-8, Brest, France, September 2000], it is known that The most efficient use is achieved by irregular or irregular repetition of information symbols.In addition, the characteristics of accumulation repetition codes are characterized to a large extent by an interleaver, which together with an irregular repetition pattern and a checksum accumulation pattern determine the Tanner graph for a given code. h To ensure sufficient spacing of repeated characters, thereby ensuring the absence or small number of code words with low weight.

There are two classes of interleavers: random and deterministic. To generate a random interleaver, a random number sensor is used, with which the number of the interleaved symbol in the sequence after interleaving is determined. The sequence of numbers obtained is checked for sufficiency of diversity of consecutive repeated information symbols with culling (rollback) of sequences that have not passed such a check. Known, in particular, the algorithm S-random [S. Dolinar and D. Divsalar “Weight Distribution for turbo codes using random and non-random permutation” JPL Progress report 42-122 pp 56-65 Aug 15.1995]. A patent is known [United States Patent 6,453,442 Sadjadpour, et al., September 17, 2002 Two stage S - Random interleaver], where a modified S-random algorithm is implemented.

The known method [Pat. 2427491 CA (0237743 WO), MKI H04L1 / 18. Automatic Request Protocol Based Packet Transmission Using Punctured Codes / R. Wang, Ming J., A. Garmonov, A. Savinkov, A. Zhdanov. –PST Gazette. - 2002, May 19. - P. 9340], where such a strategy does not lead to a decrease in throughput since additional code symbols or partial retransmission are transmitted as part of the next packet, where additional punching is performed, making room for verification code symbols for a packet in which an error is detected, thus, an error in one package is corrected due to the redundancy of another.

An example of a data communication system using a DRP interleaver (States Patent 6,857,087) is the method and apparatus of US 7673213, Keith ChuggPaul Gray, "Method and apparatus for communications using improved turbo like codes". Together with the adaptive method of speed equalization depending on channel errors [US 7975189 Cenk Kose Error rate estimation / application to code-rate adaption], the system bears the commercial name F-LDPC.

The method according to patent US 7673213 is as follows.

On the transmitting side:

- encoding data bits in accordance with an external convolutional code to create a sequence of external encoded bits;

- processing a sequence of external coded bits using an interleaver and one parity check module (SPC) to create a sequence of intermediate bits;

- encoding a sequence of intermediate bits in accordance with the internal convolutional code to create a sequence of internal encoded bits;

- processing a sequence of internally encoded bits using a puncturing module to obtain punctured bits; as well as

- combining a sequence of data bits and a sequence of punctured bits to obtain a sequence of encoded output bits.

On the receiving side:

- receiving soft decisions from the channel;

- division of soft decisions into systematic and verification parts;

- processing of the test part by adding zero bits to the punctured places;

as well as

- iterative decoding with soft input by soft output of the verification and systematic parts by an external convolutional code decoder, internal convolutional code decoder, parity decoder (SPC), using an interleaver and deinterleaver to create a sequence of decoded bits.

The method according to patent US 7975189 consists in the following:

- transmitting a first set of data encoded with a first data rate, the first data block including a first number of data bits and a first number of parity bits;

- receiving the first estimated number of bit errors for the first data set from the receiver;

- determining the first instantaneous bit rate (BER) for the first data set based on the estimated number of errors in bits received from the receiver;

- determining a second data rate depending on the first data rate and the first instantaneous BER;

- transmitting a second set of data encoded with a second data rate.

On the receiving side:

- take the first set of data encoded with a first data rate from the transmitter, and the first data set includes a first number of data bits and a first number of parity bits;

- determine the first estimated number of bit errors for the first data set received by the receiver;

- determine the first instantaneous error rate in bits for the first data set based on the estimated number of error bits in the first data block;

- determine the second data rate depending on the first data rate and the first instantaneous error rate;

- transmitting a feedback message to the transmitter indicating that the transmitter should transmit subsequent data blocks to the receiver using a second data rate; as well as

- receive a second data block from a transmitter encoded with a second data rate.

From the analysis of US 7673213, it is clear that this is a sequential combination of a convolutional code and a parity check code, that is, the commercial name F-LDPC (flexible code with a low density of parity checks) is not true, since the sequential cascading of codes usually does not satisfy low density parity checks. Serially connected codes are characterized by a dependence on the accuracy of the estimation of the noise variance in the channel. With an inaccurate estimate, the efficiency of iterative decoding by soft input decoders with a soft output drops sharply due to a sharp increase in metrics in the decoder system covered by positive feedback.

The method is based on the classic irregular repetition code with accumulations with a low density of parity checks [D. Divsalar, H. Jin, and R. J. McEliece. "Coding theorems for‘ turbo-like ’codes." Proc. 36th Allerton Conf. on Communication, Control and Computing, Allerton, Illinois, Sept. 1998, pp. 201–210.], Where a new effective interleaver is applied, and decoding quality is evaluated, that is, a decision is made on the correct reception

The disadvantage of the classical scheme when decoding according to the algorithm of "distribution of messages" is that it is difficult to coordinate speeds through punching or puncturing. When replacing the punctured character with zero and the arrival of this zero at the decoding check node, all zeros will be issued as an outgoing message, which reduces the decoding efficiency.

The closest analogue in technical essence to the proposed one is a method for transmitting voice data in a digital radio communication system according to the patent of the Russian Federation 2323520, H03M 13/00, adopted as a prototype.

A feature of the prototype method is that they evaluate the quality of decoding without using a cyclic checksum. Why consider a sequence of non-zero checksums. When the threshold value is exceeded, the packet is declared invalid decoded.

The prototype method is as follows.

On the transmitting side:

• form data packets, each of which contains an ordered sequence of information symbols;

• each information symbol is repeated a certain number of times, depending on its number in order in the sequence of characters, forming a sequence of repeated information symbols, and the number of repetitions is determined in advance;

• interleave in a sequence of repeated information symbols, achieving sufficient diversity of consecutive repeated information symbols, and forming a sequence of interleaved repeated information symbols;

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;• divide the interleaved repeated information symbols into groups so that the first verification symbol is obtained by summing, according to a given module, the initial value of the summation variable with all interleaved repeated information symbols from the first group, and the verification symbol

by summing the specified character of the check character

with all interleaved repeated information symbols from the group

;

• remember received verification characters;

• form a code word by adding test characters to information characters;

on the receiving side:

• form the received correlation responses to each of the transmitted code symbols;

• evaluate the noise parameter of the signal plus noise mixture, which is approximately equal to the standard deviation of the equivalent Gaussian white noise, which approximates the noise in the channel;

• form soft decisions about the adopted code symbols using the obtained estimate of the noise parameter of the signal plus noise mixture;

• share soft decisions on accepted code symbols into decisions on information symbols and decisions on verification symbols;

• repeat soft decisions about information symbols in accordance with the pattern of repeating information symbols;

• repeat soft decisions about check characters at least twice except for the last check character;

• for soft decisions about information symbols, they perform interleaving similar to interleaving on the transmitting side;

• form groups of interleaved soft decisions about information symbols similar to groups of corresponding information symbols on the transmitting side;

• the first group of interleaved soft solutions is supplemented with the soft solution corresponding to the initial value of the summation variable and the first copy of the soft decision about the first check character, forming the first code word of the general parity check code;

• группу перемеженных мягких решений дополняют второй копией

проверочного символа и первой копией мягкого решения об

проверочном символе, образуя

кодовое слово кода обобщенной проверки на четность;

• complement the group of interleaved soft solutions with a second copy

test character and the first copy of the soft decision about

check character, forming

generalized parity check codeword;

• for each soft decision included in each code word of the generalized parity check code, a modified soft solution is formed, which is an outgoing message of the code word of the general parity check code, so that the outgoing message of the code word of the general parity check code is the result functional transformation of the original soft decisions - incoming messages of the code word of the code of a generalized parity check;

• deinterleave the outgoing message of the code word of the generalized parity check code so that each copy of the soft decision on the code symbol is associated with the outgoing message of the code word of the generalized parity code corresponding to the copy of the soft decision about this symbol;

• group outgoing messages of the code word of the generalized parity check code with soft decisions about the received code symbols, so that each group includes a soft decision about the corresponding code symbol and outgoing messages of the code word of the generalized parity code corresponding to a copy of the soft decision about this symbol, thus forming the code word of the generalized repetition code, putting each codeword of the generalized repetition code in accordance with the code symbol, so that each outgoing the codeword of the generalized parity check code is an incoming message of the codeword of the generalized repetition code;

• for each soft decision of the generalized repetition code included in each codeword, a modified soft decision is formed, which is an outgoing message of the generalized code of the repetition code representing the result of a functional transformation over the incoming messages of the code word of the generalized repetition code;

• iteratively repeat the process of exchanging outgoing and incoming messages in such a way that the outgoing message of the code word of the generalized repetition code is the incoming message of the code word of the generalized parity check code, and the outgoing message of the code of the generalized parity check code is the incoming message of the code word of the generalized repetition code iterating a sequence of modified soft solutions;

• decoded codewords are formed from a sequence of modified soft decisions;

• Multiply each decoded codeword by a check matrix, obtaining an ordered sequence of checksums;

• if all checksums are equal to zero, then the codeword is considered decoded correctly;

• if the number of checksums other than zero is odd and the last checksum is different from zero, then replace it with zero;

• if the number of checksums other than zero is odd and the last checksum in the sequence is zero, then it is replaced with any nonzero value;

• break down the sequence of checksums into pairs, which consist of sequential elements of a sequence, and each checksum is included only in a single pair;

• in each pair, the difference in the numbers of the checksums is calculated;

• add up all the received checksum number differences;

• compare the received number with a given threshold, if the number exceeds the set threshold, then the information part of the code word is considered decoded incorrectly;

• if the received number is less than the specified threshold, then the information part of the code word is considered decoded correctly.

The prototype implements not only an error correction function, but also an error detection function without a cyclic checksum. However, the error detection efficiency is significantly inferior to the cyclic checksum algorithm. Nevertheless, the error detection function can be used to increase the coding energy gain by applying a hybrid repeat-request algorithm without losing bandwidth and without resorting to punching a sequence of code symbols. Thus, the task of increasing the energy gain of coding by applying the hybrid request-repeat algorithm exclusively at the physical level is relevant.

путем суммирования по заданному модулю проверочного символа

со всеми перемеженными повторенными информационными символами из группы

, запоминают полученные проверочные символы, формируют кодовое слово путем добавления проверочных символов к информационным символам, на приемной стороне формируют принятые корреляционные отклики на каждый из переданных кодовых символов, выполняют оценку шумового параметра смеси сигнал плюс шум, формируют мягкие решения о принятых кодовых символах, используя полученную оценку шумового параметра смеси сигнал плюс шум, разделяют мягкие решения о принятых кодовых символах на решения об информационных символах и решения о проверочных символах, повторяют мягкие решения об информационных символах в соответствии с шаблоном повторения информационных символов, повторяют мягкие решения о проверочных символах, по крайней мере, два раза за исключением последнего проверочного символа, для мягких решений об информационных символах выполняют перемежение аналогичное перемежению на передающей стороне, формируют группы перемеженных мягких решений об информационных символах, аналогичные группам соответствующих информационных символов на передающей стороне, первую группу перемеженных мягких решений дополняют мягким решением, соответствующим начальному значению переменной суммирования, и первой копией мягкого решения о первом проверочном символе, образуя первое кодовое слово кода обобщенной проверки на четность,

группу перемеженных мягких решений дополняют второй копией

проверочного символа и первой копией мягкого решения об

проверочном символе, образуя

кодовое слово кода обобщенной проверки на четность, для каждого мягкого решения, входящего в каждое кодовое слово кода обобщенной проверки на четность, формируют модифицированное мягкое решение, которое является исходящим сообщением кодового слова кода обобщенной проверки на четность таким образом, что исходящее сообщение кодового слова кода обобщенной проверки на четность представляет собой результат функционального преобразования исходных мягких решений, представляющих собой входящие сообщения кодового слова кода обобщенной проверки на четность, деперемежают исходящие сообщения кодового слова кода обобщенной проверки на четность таким образом, что каждой копии мягкого решения о кодовом символе ставят в соответствие исходящее сообщение кодового слова кода обобщенной проверки на четность соответствующее копии мягкого решения об этом символе, группируют исходящие сообщения кодового слова кода обобщенной проверки на четность с мягкими решениями о принятых кодовых символах, так что в каждую группу входят мягкое решение о соответствующем кодовом символе и исходящие сообщение кодового слова кода обобщенной проверки на четность, соответствующее копии мягкого решения об этом символе, формируя, таким образом, кодовое слово обобщенного кода повторения, ставя каждое кодовое слово обобщенного кода повторения в соответствие кодовому символу, таким образом, что каждое исходящее сообщение кодового слова кода обобщенной проверки на четность является входящим сообщением кодового слова обобщенного кода повторения, для каждого мягкого решения, входящего в каждое кодовое слово обобщенного кода повторения, формируют модифицированное мягкое решение, которое является исходящим сообщением кодового обобщенного кода повторения, представляющее собой результат функционального преобразования над входящими сообщениями кодового слова обобщенного кода повторения, итеративно повторяют процесс обмена исходящими и входящими сообщениями таким образом, что исходящее сообщение кодового слова обобщенного кода повторений является входящим сообщением кодового слова кода обобщенной проверки на четность, а исходящее сообщение кода обобщенной проверки на четность является входящим сообщением кодового слова обобщенного кода повторений, формируя на каждой итерации последовательность модифицированных мягких решений, из последовательности модифицированных мягких решений формируют декодированные кодовые слова, умножают каждое декодированное кодовое слово на проверочную матрицу, получая упорядоченную последовательность контрольных сумм, если все контрольные суммы равны нулю, то кодовое слово считают декодированным верно, если количество контрольных сумм отличных от нуля нечетно и последняя контрольная сумма отлична от нуля, то заменяют ее нулем, если количество контрольных сумм отличных от нуля нечетно, и последняя в последовательности контрольная сумма равна нулю, то ее заменяют любым отличным от нуля значением, разбивают последовательность контрольных сумм на пары, в которые входят элементы последовательности, идущие подряд, причем каждая контрольная сумма входит только в единственную пару, в каждой паре вычисляют разность номеров контрольных сумм, складывают все полученные разности номеров контрольных сумм, сравнивают полученное число с заданным порогом, если число превышает установленный порог, то информационную часть кодового слова считают декодированной неверно, если полученное число меньше заданного порога, то информационную часть кодового слова считают декодированной верно, согласно изобретению, если информационная часть кодового слова декодирована неверно то формируют сигнал запроса повторной передачи по каналу обратной связи для передающей стороны, на передающей стороне при получении сигнала запроса повторной передачи формируют пакет с кодово-сопряженной частью, для чего в очередном кодированном пакете часть кодовых символов заменяют суммой по модуля два с кодовыми символами ранее переданного и ошибочно декодированого пакета, формируя тем самым кодово-сопряженную часть, при получении текущего пакета с кодово-сопряженной частью декодируют его совместно с ранее принятым ошибочно декодированным пакетом для чего восстанавливают, возможно, с ошибками, последовательность мягких решений ошибочного пакета, модифицируют мягкие решения в кодово-сопряженной части в тех позициях, в которых заменяли кодовые символы суммой символов разных пакетов для чего заменяют знак на противоположный у принятого мягкого решения, если восстановленный кодовый символ предыдущего пакета соответствует логической единице, получая мягкие решения текущего пакета, декодируют мягкие решения текущего пакета, восстанавливают последовательность мягких решений текущего пакета, модифицируют мягкие решения в кодово-сопряженной части в тех позициях, в которых заменяли кодовые символы суммой символов разных пакетов для чего заменяют знак на противоположный у принятого мягкого решения если восстановленный кодовый символ текущего пакета соответствует логической единице, получая модифицированную последовательность мягких решений для ошибочного пакета, повторно декодируют ошибочный пакет, используя модифицированную последовательность мягких решений для ошибочного пакета как дополнительную информацию в тех позициях, в которых заменяли кодовые символы суммой символов разных пакетов, передают по каналу обратной связи сигналы, характеризующие результативность декодирования кодово-сопряженных пакетов.To solve the problem in a method of transmitting data in a digital communication system, which consists in the fact that data packets are formed on the transmitting side, each of which contains an ordered sequence of information symbols, each information symbol is repeated a certain number of times, depending on its number in order symbol sequences, forming a sequence of repeated information symbols, moreover, the number of repetitions is determined in advance, interleaving in sequence and repeated information symbols, achieving sufficient diversity of consecutive repeated information symbols, and forming a sequence of interleaved repeated information symbols, divide the interleaved repeated information symbols into groups so that the first verification symbol is obtained by summing, according to a given module, the initial value of the summation variable with all interleaved repeated information symbols from the first group, and the verification symbol

by summing the specified character of the check character

with all interleaved repeated information symbols from the group

, the received verification symbols are stored, the code word is formed by adding the verification symbols to the information symbols, received correlation responses to each of the transmitted code symbols are generated on the receiving side, the noise plus signal noise parameter is estimated, soft decisions about the received code symbols are generated using the received estimation of the noise parameter of the signal plus noise mixture, soft decisions on accepted code symbols are divided into decisions on information symbols and decisions on test mvolov, repeat soft decisions about information symbols in accordance with the pattern of repeating information symbols, repeat soft decisions about check symbols at least two times with the exception of the last check symbol, for soft decisions about information symbols perform interleaving similar to interleaving on the transmitting side, form groups of interleaved soft decisions about information symbols, similar to groups of corresponding information symbols on the transmitting side, the first group of soft-low solutions are supplemented with a soft solution corresponding to the initial value of the variable of summation, and the first copy of the soft decision about the first check character, forming the first code word of the general parity check code,

a group of interleaved soft solutions complement the second copy

test character and the first copy of the soft decision about

check character, forming

the codeword of the code of the generalized parity check, for each soft decision that is included in each codeword of the code of the generalized parity, form a modified soft solution that is an outgoing message of the code word of the code of the general parity code so that the outgoing message of the code word of the code of generalized parity is the result of a functional transformation of the original soft decisions, which are incoming messages of the code word of the code of the generalized verification of parity, deinterleave the outgoing message of the code word of the generalized parity check code so that each copy of the soft decision about the code symbol matches the outgoing message of the code word of the generalized parity code corresponding to the copy of the soft decision about this symbol, group the outgoing messages of the code word generalized parity check code with soft decisions about accepted code characters, so that each group includes a soft decision about the corresponding code character and the outcome The message contains the code word of the generalized parity check code corresponding to the copy of the soft decision on this symbol, thus forming the code word of the generalized repetition code, putting each code word of the generalized repetition code in correspondence with the code symbol, so that each outgoing message of the code word the generalized parity check code is an incoming message of the codeword of the generalized repetition code, for each soft solution included in each codeword of the generalized repetition code I, form a modified soft solution, which is an outgoing message of a code generalized repetition code, which is the result of a functional transformation of the code word of a generalized repetition code over incoming messages, iteratively repeat the process of exchanging outgoing and incoming messages in such a way that the outgoing message of the code word of a generalized repetition code is the incoming message of the code word of the generalized parity check code, and the outgoing message of the code code of the generalized parity A parity key is an incoming message of a code word of a generalized repetition code, forming a sequence of modified soft decisions at each iteration, decoded code words are formed from a sequence of modified soft decisions, each decoded code word is multiplied by a check matrix, getting an ordered sequence of checksums if all the checksums are equal to zero, then the codeword is considered decoded correctly if the number of non-zero checksums is odd and the last checksum is non-zero, then replace it with zero, if the number of checksums other than zero is odd, and the last checksum in the sequence is zero, then it is replaced with any non-zero value, break the sequence of checksums into pairs, which include sequence elements in a row, each checksum being included only in a single pair, in each pair the difference in the numbers of the checksums is calculated, all the differences in the numbers of the checksums are added m, the received number is compared with a predetermined threshold, if the number exceeds the set threshold, then the information part of the codeword is considered decoded incorrectly, if the received number is less than the specified threshold, then the information part of the code word is considered decoded correctly, according to the invention, if the information part of the codeword is decoded incorrectly then form a retransmission request signal on the feedback channel for the transmitting side, on the transmitting side upon receipt of the retransmission request signal form Coziness is a packet with a code-conjugate part, for which, in the next coded packet, a part of the code symbols is replaced by a module sum of two with the code symbols of a previously transmitted and erroneously decoded packet, thereby forming a code-conjugate part, and upon receipt of the current packet with a code-conjugate part, decode it, together with the previously received erroneously decoded packet, for which, possibly with errors, the sequence of soft decisions of the erroneous packet is restored, soft decisions are modified in the code-conjugate part in those positions in which the code symbols were replaced by the sum of the symbols of different packets, for which the sign is replaced with the opposite for the adopted soft decision, if the reconstructed code symbol of the previous packet corresponds to a logical unit, receiving soft decisions of the current packet, decode the soft decisions of the current packet, restoring the sequence of soft decisions the current package, soft solutions are modified in the code-conjugate part at those positions in which the code symbols were replaced by the sum of the symbols of different packets for o replace the opposite sign for the adopted soft decision if the recovered code symbol of the current packet corresponds to a logical unit, receiving a modified sequence of soft decisions for an erroneous packet, re-decode the error packet using the modified sequence of soft decisions for an erroneous packet as additional information at those positions in which replaced the code symbols with the sum of the symbols of different packets, transmit signals characterizing the results via the feedback channel The property of decoding code-conjugate packets.

Graphic materials used in the description:

FIG. 1 - graph decoding algorithm: messaging.

FIG. 2 - Peterson's graph and the code set on it according to the Tanner method.

FIG. 3 is an embodiment of a transmitting part of a digital communication system for transmitting data.

FIG. 4 is an embodiment of a receiving part of a digital communication system for transmitting data.

FIG. 5 is an embodiment of an iterative decoder.

FIG. 6 is a method for detecting errors without CRC.

FIG. 7 is a method of interleaving code symbols.

FIG. 8 - simulation results.

The inventive method of transmitting data in a digital communication system, is that

on the transmitting side:

- form data packets, each of which contains an ordered sequence of information symbols;

- each information symbol is repeated a certain number of times, depending on its number in order in the sequence of characters, forming a sequence of repeated information symbols, moreover, the number of repetitions is determined in advance;

- carry out the interleaving in the sequence of repeated information symbols, achieving sufficient diversity of consecutive repeated information symbols, and forming a sequence of interleaved repeated information symbols;

путем суммирования по заданному модулю проверочного символа

со всеми перемеженными повторенными информационными символами из группы

; - split the interleaved repeated information symbols into groups so that the first verification symbol is obtained by summing, according to a given module, the initial value of the summation variable with all interleaved repeated information symbols from the first group, and the verification symbol

by summing the specified character of the check character

with all interleaved repeated information symbols from the group

;

- remember received verification characters;

- form a code word by adding test characters to information characters;

on the receiving side:

- form the received correlation responses to each of the transmitted code symbols;

- evaluate the noise parameter of the signal plus noise mixture, which is approximately equal to the standard deviation of the equivalent Gaussian white noise, which approximates the noise in the channel;

- form soft decisions about the adopted code symbols using the obtained estimate of the noise parameter of the signal plus noise mixture;

- divide soft decisions about accepted code symbols into decisions about information symbols and decisions about check symbols;

- repeat soft decisions about information symbols in accordance with the pattern of repetition of information symbols;

- repeat soft decisions about check characters at least twice except for the last check character;

- for soft decisions about information symbols, interleaving is performed similar to interleaving on the transmitting side;

- form groups of interleaved soft decisions about information symbols similar to groups of corresponding information symbols on the transmitting side;

- the first group of interleaved soft solutions is supplemented with the soft solution corresponding to the initial value of the summation variable, and the first copy of the soft decision about the first check character, forming the first code word of the general parity check code;

группу перемеженных мягких решений дополняют второй копией

проверочного символа и первой копией мягкого решения об

проверочном символе, образуя

кодовое слово кода обобщенной проверки на четность;-

a group of interleaved soft solutions complement the second copy

test character and the first copy of the soft decision about

check character, forming

generalized parity check codeword;

- for each soft decision included in each code word of the generalized parity check code, a modified soft solution is formed, which is an outgoing message of the code word of the general parity check code, so that the outgoing message of the code word of the general parity check code is the result functional transformation of the original soft decisions - incoming messages of the code word of the code of a generalized parity check;

- deinterleave the outgoing message of the code word of the generalized parity check code in such a way that each copy of the soft decision on the code symbol is associated with the outgoing message of the code word of the generalized parity code corresponding to the copy of the soft decision about this symbol;

- group outgoing messages of the code word of the generalized parity check code with soft decisions about the received code symbols, so that each group includes a soft decision about the corresponding code symbol and outgoing messages of the code word of the generalized parity code corresponding to a copy of the soft decision about this symbol, thus forming the code word of the generalized repetition code, putting each codeword of the generalized repetition code in accordance with the code symbol, so that each outgoing the codeword of the generalized parity check code is an incoming message of the codeword of the generalized repetition code;

- for each soft decision of the generalized repetition code included in each codeword, a modified soft solution is formed, which is an outgoing message of the generalized code of the repetition code representing the result of a functional transformation over the incoming messages of the code word of the generalized repetition code;

- iteratively repeat the process of exchanging outgoing and incoming messages in such a way that the outgoing message of the code word of the generalized repetition code is the incoming message of the code word of the generalized parity check code, and the outgoing message of the code of the generalized parity check code is the incoming message of the code word of the generalized repetition code iterating a sequence of modified soft solutions;

- decoded codewords are formed from a sequence of modified soft decisions;

- multiply each decoded codeword by a check matrix, obtaining an ordered sequence of checksums;

- if all the checksums are equal to zero, then the code word is considered decoded correctly;

- if the number of checksums other than zero is odd and the last checksum is different from zero, then replace it with zero;

- if the number of non-zero checksums is odd and the last checksum in the sequence is zero, then it is replaced with any non-zero value;

- break down the sequence of checksums into pairs, which include sequential elements of the sequence, and each checksum is included only in a single pair;

- in each pair, the difference in the numbers of the checksums is calculated;

- add up all the received differences of the numbers of the checksums;

- compare the received number with a given threshold, if the number exceeds the set threshold, then the information part of the code word is considered decoded incorrectly;

- if the received number is less than a given threshold, then the information part of the codeword is considered decoded correctly;

 - if the information part of the codeword is decoded incorrectly, a retransmission request signal is generated on the feedback channel for the transmitting side;

- on the transmitting side, upon receipt of the retransmission request signal, a packet with a code-conjugate part is formed, for which, in the next encoded packet, part of the code symbols is replaced by the sum of two modules with the code symbols of the erroneously decoded packet;

- upon receipt of the current packet with the code-conjugate part, it is decoded together with the previously received erroneously decoded packet, for which, possibly with errors, the sequence of soft decisions of the erroneous packet is restored;

- subtracted soft solutions from the code-conjugate part of the packet in those positions in which the code symbols were replaced by the sum of the symbols of different packets, obtaining soft solutions of the current packet;

- decode soft decisions of the current package;

- restore the sequence of soft decisions of the decisions of the current package;

- subtracted from the code-conjugate part of the current packet, the restored soft solutions of the current package in those positions in which the code symbols were replaced by the sum of the symbols of different packets to obtain a modified sequence of soft decisions for the erroneous packet;

- re-decode the erroneous packet using a modified sequence of soft decisions for the erroneous packet as additional information, in those positions in which the code symbols were replaced by the sum of the symbols of different packets;

- transmit signals on the feedback channel characterizing the decoding performance of code-conjugate packets.

To implement the proposed method, a communication system can be used, the transmitting device (transmitting side) of which is shown in FIG. 3, and the receiving device (receiving side) is shown in FIG. four.

The transmitter shown in FIG. 3, contains a series of information symbol repetition unit 1, an information symbol interleaver 2, a check symbol separation unit 3, a summing unit 5, a memory unit 8, an inter-packet summing unit 7, and a multiplexer 6, the output of which is connected to the communication channel 9. In addition to Moreover, the transmitting device comprises a control unit 4, the signals from the outputs of which are control signals, which, inter alia, provide synchronization of the remaining blocks. The first output of the control unit 4 is connected to the second input of the information symbol repetition unit 1, the second output of the control unit 4 is connected to the second input of the information symbol interleaver 2, the third output of the control unit 4 is connected to the second input of the unit for separating test characters into groups 3, the fourth output of the unit control 4 is connected to the second input of the summing unit 5, the fifth output of the control unit 4 is connected to the second input of the memory unit 8, the sixth output of the control unit 4 is connected to the second input of the inter-packet block ummirovaniya 7, the seventh control unit 4 output is connected to a second input of multiplexer 6. A second output of the memory unit 8 is connected to a third input of the summing inter-packet 7 and a third input of the multiplexer 6.

The first input of the information symbol repetition unit 1 is the first input of the transmitting device to which the data packets arrive, the same input is connected to the first input of the multiplexer 6. The first input of the control unit 4 is the input of the feedback signal to automatically request repetition, it is the second input of the transmitting devices.

Through the communication channel 9, the signal is supplied to the receiving device.

The receiver of FIG. 4, contains in series a block for generating correlation responses and estimating a noise parameter 10, a soft decision separation unit 11, a check symbol repetition unit 12, an interleaved soft decision generating unit 15, a first iterative decoder 16, a checksum calculation unit in the decoded codeword 17, a block error control in the decoded codeword 18, the output of which is the first output of the receiving device. The output of the soft decision separation unit 11 through series-connected information symbol repeater 13 and the information symbol interleaver 14 is connected to the second input of the interleaved soft decision unit 15, the output of which is connected to the input of the soft decision storage and subtraction unit 19, the first input-output of which connected in series to the second iterative decoder 20, the checksum calculation unit in the decoded codeword 21, and the error control unit in the decoded codeword 22 is connected feedback channel input 23. In this case, the second output of the error control block in the decoded codeword 22 is connected to the second input of the second iterative decoder 20. The second input-output of the soft decision storage and subtraction unit 19 is connected to the input-output of the first iterative decoder 16, the second input which is connected to the third output of the error control unit in the decoded codeword 18, the second output of which is connected to the second input of the feedback channel 23. The second output of the block for generating correlation responses and estimating noise of parameter 10 is connected to the third input of the block for forming interleaved soft decisions 15.

The input of the receiving device is the input of the block for generating correlation responses and estimating the noise parameter 10, which receives a signal from the transmitting device through the communication channel 9. The second output of the error control unit in the decoded codeword 22 is the second output of the receiving device.

Iterative decoders 16 and 20 are identical, therefore, we consider an embodiment of the first iterative decoder 16 shown in FIG. 5. The first iterative decoder 16 comprises a generalized parity check decoding unit 24, a first de-interleaver 25, a second de-interleaver 26, a repeat code decoding unit 27, a control unit of the decoder 28, a memory unit 29, a first switch 30, an interleaver 31, and a second switch 32.

The first input of the first switch 30 is connected to the output of the interleaved soft decision forming unit 15 (Fig. 4), the second input of the switch 30 is connected to the first output of the control unit of the decoder 28, the input of which is connected to the output of the error control unit in the decoded codeword 18. The third input of the first the switch 30 is the input / output of the memory unit 29. The first output of the first switch 30 is the output of soft decisions from each code word of the generalized parity check code and is connected to the input of the generalized test decoding unit parity 24, the output of which through the first deinterleaver 25 is connected to the first input of the repeat code decoding unit 27. The second output of the first switch 30 is the output of soft code symbol decisions stored in the memory unit 29 and is connected through the de-interleaver 26 to the second input of the repeat code decoding unit 27. The first output of the repetition code decoding unit 27, which is the output of the outgoing messages of the code generalized code, is connected through the first input of the second switch 32 to the input of the interleaver 31, the output of which of the second is connected to the fourth input of the first switch 30. The second output of the repeat code decoding unit 27, which is the output of the decoded codeword, is connected to the second input of the second switch 32, the third input of which is the control input and connected to the second output of the decoder 28 control unit. the switch 32 is connected to the input of the checksum calculation unit in the decoded codeword 17. The synchronization signals in Fig. 5 are not shown to simplify the circuit.

The device operates as follows.

путем суммирования по заданному модулю проверочного символа

со всеми перемеженными повторенными информационными символами из группы

. Полученные проверочные символы запоминают блоке памяти 8. Запомненные проверочные символы поступают в мультиплексор 6, где формируют кодовое слово путем добавления проверочных символов к информационным символам. Через канал связи 9 сформированное кодовое слово передают на приемное устройство. В случае получения по каналу обратной связи сигнала запроса на повторную передачу формируют пакет с кодово-сопряженной частью, для чего в блоке межпакетного суммирования 7 суммируют кодовые символы текущего пакета с кодовыми символами ошибочно декодированного пакета, сохраненного в блоке памяти 8. В мультиплексоре 6 мультиплексируют кодово-сопряженную часть пакета, полученную с блока межпакетного суммирования 7 и кодовые символы текущего пакета, которые также сохраняют в блоке памяти 8.On the transmitting side, the generated data packets, each of which contains an ordered sequence of information symbols, receive the input of the information symbol repetition unit 1 and simultaneously to the first input of the multiplexer 6. In the information symbol repetition unit 1, each information symbol is repeated a certain number of times, depending on its number in order in the sequence of characters, forming a sequence of repeated information symbols, moreover, the number of repetitions is determined in advance e. The sequence of repeated information symbols from the output of the information symbol repetition unit 1 is fed to the input of the information symbol interleaver 2, where interleaving is performed in the sequence of repeated information symbols, achieving sufficient diversity of successive repeated information symbols and forming a sequence of interleaved repeated information symbols. In the block for dividing the check symbols into groups 3, interleaved repeated information symbols are divided into groups, then in the summing unit 5, the first check symbol is obtained by summing the initial value of the summation variable with all interleaved repeated information symbols from the first group by the given module, and the check symbol

by summing the specified character of the check character

with all interleaved repeated information symbols from the group

. The received verification symbols are stored in the memory unit 8. The stored verification symbols are transmitted to the multiplexer 6, where a codeword is formed by adding verification symbols to the information symbols. Through the communication channel 9, the generated codeword is transmitted to the receiving device. If a retransmission request signal is received via the feedback channel, a packet with a code-conjugate part is formed, for which the code symbols of the current packet with the code symbols of the erroneously decoded packet stored in the memory block 8 are summed in the inter-packet summing block 7, and the code multiplexer 6 is multiplexed - the conjugate part of the packet received from the inter-packet summing block 7 and the code symbols of the current packet, which are also stored in the memory block 8.

группу перемеженных мягких решений дополняют второй копией

проверочного символа и первой копией мягкого решения об

проверочном символе, образуя

кодовое слово кода обобщенной проверки на четность. Сформированные перемеженные мягкие решения поступают на первый вход первого итеративного декодера 16 (на первый коммутатор 26 фиг. 5), в котором формируется декодированное кодовое слово. Каждое декодированное кодовое слово в блоке вычисления контрольных сумм в декодированном кодовом слове 17 умножают на проверочную матрицу, получая упорядоченную последовательность контрольных сумм, если все контрольные суммы равны нулю, то кодовое слово считают декодированным верно, если количество контрольных сумм отличных от нуля нечетно и последняя контрольная сумма отлична от нуля, то заменяют ее нулем, если количество контрольных сумм отличных от нуля нечетно и последняя в последовательности контрольная сумма равна нулю, то ее заменяют любым отличным от нуля значением, разбивают последовательность контрольных сумм на пары, в которые входят элементы последовательности, идущие подряд, причем каждая контрольная сумма входит только в единственную пару, в каждой паре вычисляют разность номеров контрольных сумм, складывают все полученные разности номеров контрольных сумм. Затем в блоке контроля ошибок в декодированном кодовом слове 18 сравнивают полученное число с заданным порогом, если число превышает установленный порог, то информационную часть кодового слова считают декодированной неверно, если полученное число меньше заданного порога, то информационную часть кодового слова считают декодированной верно. On the receiving side, the code word generated in the transmitter is input to the block for generating correlation responses and estimating the noise parameter 10, where the received correlation responses to each of the transmitted code symbols are generated and the noise parameter of the signal plus noise mixture is estimated, which is approximately equal to the standard deviation of the equivalent Gaussian white noise, which approximates the interference in the channel, and then form soft decisions about the received code symbols using the resulting estimate The smart parameter of the signal plus noise mixture. The resulting soft decisions go to the input of the soft decision separation unit 11, where the soft decisions about the adopted code symbols are divided into decisions about information characters and decisions about check characters. Soft decisions about information symbols from the soft decision separation unit 11 are fed to the input of the information symbol repetition block 13, where soft decisions about information symbols are repeated in accordance with the information symbol repetition pattern. Soft decisions about the test characters from the soft decision separation unit 11 are input to the test character repetition unit 12, where soft decisions about the test characters are repeated at least two times, with the exception of the last check character. For soft decisions about information symbols, interleaving is performed similar to interleaving on the transmitting side in the block of interleaving information symbols 14. Then, in the block for generating interleaved soft decisions 15, groups of interleaved soft decisions about information symbols similar to the groups of corresponding information symbols on the transmitting side are formed using signals from the block of verification characters 12 and from the block for the formation of correlation responses and estimates of the noise parameter 10, and the first group of interleaved soft solutions complement the soft solution corresponding to the initial value of the variable summation, and the first copy of the soft decision on the first check character, forming the first code word of a code for generalized parity,

a group of interleaved soft solutions complement the second copy

test character and the first copy of the soft decision about

check character, forming

generalized parity code code word. The generated interleaved soft decisions are sent to the first input of the first iterative decoder 16 (to the first switch 26 of FIG. 5), in which a decoded codeword is generated. Each decoded codeword in the checksum calculation unit in the decoded codeword 17 is multiplied by a check matrix to obtain an ordered sequence of checksums; if all the checksums are equal to zero, then the code word is considered decoded correctly if the number of non-zero checksums is odd and the last check the sum is nonzero, then replace it with zero, if the number of checksums other than zero is odd and the last checksum in the sequence is zero, then for enyayut any nonzero value, divide the sequence of checksums in pairs, which include elements of a sequence, consecutive, each checksum includes only a single pair, each pair calculated difference numbers checksums are folded all the obtained difference numbers checksums. Then, in the error control unit in the decoded codeword 18, the obtained number is compared with a predetermined threshold; if the number exceeds a set threshold, then the information part of the codeword is considered decoded incorrectly; if the received number is less than the specified threshold, then the information part of the codeword is considered decoded correctly.

The reconstructed check symbols of the packet in which the error was detected are stored in the soft decision storage and subtraction unit 19, where the reconstructed soft solutions are subtracted from the code-conjugate part of the packet at the positions in which the code symbols are replaced by the sum of the symbols of different packets, obtaining soft solutions of the current packets that are used as additional information when decoding the current packet by the first iterative decoder 16. The reconstructed sequence of soft decisions of the current packet is stored in block x injured and subtracted soft solutions 19, in the same place, the restored soft solutions of the current package are subtracted from the code-conjugate part of the current package at the positions in which the code symbols were replaced by the sum of the symbols of different packages, obtaining a modified sequence of soft solutions for the erroneous package. The error packet is re-decoded by the second iterative decoder 20, using the modified sequence of soft decisions for the error packet, as additional information at those positions in which the code symbols were replaced by the sum of the symbols of different packets. Transmit via feedback channel 23 signals characterizing the decoding performance of code-conjugate packets.

The error detection algorithm in the codeword is shown in FIG. 6.

The detection of errors in the inventive method of transmitting data in a digital communication system can be explained by the following example. Suppose we have a “repeat with accumulation” code given by a bipartite regular graph. Consider the various error configurations. Note the case where there are erroneously decoded vertex variables, but all checksums are equal to zero. This is a case of an undetectable error. Consider also the case where errors are only in the verification part of the codeword. Note that each error in the verification part causes two neighboring checksums to be zero. However, non-zero checksums with an error in the information part are spaced a distance proportional to the spacing parameter of the interleaver. Thus, in the presence of a single error, it is easy to determine which symbol it refers to: informational or verification. To do this, it suffices to consider the difference in the numbers of test vertices corresponding to non-zero checksums. If such a difference is 1, then the erroneous character can be unambiguously attributed to the test characters, if more, then the erroneous character is informational.

Turning to the case of many errors, the algorithm is as follows:

• if the number of non-zero checksums is odd, then the control value of the last amount is changed, achieving an even number of checksums;

• consistently break the checksums into pairs, calculate the sum of the differences of the addresses of the test vertices;

• compare the obtained value with the threshold; if it is less than the threshold, then the errors are referred only to check symbols.

Thus, error detection is carried out without CRC, thereby improving the quality of radio communications by reducing the number of redundant transmitted code symbols, while simultaneously detecting and correcting errors.

The first iterative decoder 16 shown in FIG. 5, works as follows.

According to the signal from the control unit of the decoder 28, the switch 30 commutes soft decisions from each code word of the generalized parity check code to the input of the decoding unit of the generalized parity check code and stores them in the memory unit 29. In the decoding block of the generalized parity check code 24 for each soft the solutions included in each codeword of the generalized parity check code form a modified soft solution, which is an outgoing message of the codeword of the generalized parity check code, so It means that the outgoing message of the code word of the code of the generalized parity check is the result of the functional transformation of the original soft solutions - incoming messages of the code word of the code of the generalized parity check. In the de-interleaver 25, the outgoing messages of the code word of the generalized parity check code are de-interleaved so that each copy of the soft decision on the code symbol is associated with the outgoing message of the code word of the generalized parity code corresponding to the copy of the soft decision on this symbol. Soft code symbol decisions stored in the memory unit 29 are de-interleaved through the switch 30 in the de-interleaver 26 in such a way that each copy of the soft code symbol decision stored in the memory unit 29 is assigned an outgoing code word message of the generalized parity code of the de-interleaved code in block 25, the corresponding copy of the soft decision about this symbol. The deinterleaved soft decisions from blocks 25 and 26 go to the repetition code decoding unit 27, for each soft decision of the generalized repetition code included in each codeword, a modified soft decision is formed, which is the outgoing message of the generalized repetition code, which is the result of a functional transformation over incoming messages codeword of a generic repetition code. By the control signal from the control unit of the decoder 28, the switch 32 passes to the interleaver 31 outgoing messages the code words of the generalized repetition code, where they are interleaved, or the decoded code words generated in the decoding unit of the repetition code 27 by the corresponding signal of the control unit 28 of the switch 32 to the control calculation unit sums in the decoded codeword 17.. Iteratively repeat the process of exchanging outgoing and incoming messages in such a way that the outgoing message of the code word about a generalized repetition code is an incoming message of a code word of a generalized parity check code, and an outgoing message of a code of a generalized parity check code is an incoming message of a code word of a generalized repetition code, forming a sequence of modified soft decisions at each iteration, decoded code words are formed from a sequence of modified soft decisions.

All blocks included in the communication system can be implemented on the processor, FPGA, specialized chip.

For the inventive method for transmitting data in a digital radio communication system based on codes with a low density of parity checks, the proposed method for interleaving code symbols is used.

A known method of interleaving a sequence of code symbols according to RF patent 2323520, H03M 13/00, (claim 6), in which a sequence of code symbols is divided into many subsequences, each of which is interleaved using a pilot pseudorandom sequence, which is set by setting Hamilton paths on a regular tetravalent graph. The pilot pseudo-random sequence is defined as follows. Suppose that there is a Hamiltonian path in the graph, and the numbering of the vertices of the graph corresponds to the order of passage of this path. A pilot pseudorandom sequence is defined if there is another Hamiltonian path passing along the edges of the graph that did not participate in the first path. When passing along the second Hamiltonian path, a sequence of numbers of passed vertices is obtained, given when passing along the first path, which defines a pilot pseudorandom sequence.

The disadvantage of this method of interleaving is the slightly worse noise immunity characteristics compared to the following variant of interleaving code symbols (RF patent 2323520, H03M 13/00, interleaving code symbols according to claim 9)

The closest analogue in technical essence to the proposed one is "A method for transmitting voice data in a digital radio communication system and a method for interleaving a sequence of code symbols (options)", RF patent 2323520, H03M 13/00, interleaving code symbols according to claim 9, adopted as a prototype.

The prototype method is as follows:

• break the sequence of characters for interleaving into subsequences of characters for interleaving;

• exchange code symbols between and / or within subsequences, forming interleaved subsequences of code symbols;

• form the final interleaved sequence from subsequences;

символов для перемежения на две подпоследовательности символов для перемежения в первую из которых входят

символов для перемежения, а во вторую

символов для перемежения, причем формируют первую и вторую подпоследовательность таким образом, что в первой подпоследовательности выполняется условие

, • break the sequence

characters for interleaving into two subsequences of characters for interleaving, the first of which includes

characters for interleaving, and in the second

characters for interleaving, and form the first and second subsequence so that in the first subsequence the condition

,

, где

– номера кодовых символов до перемежения, а

– номера кодовых символов после перемежения,

– целые положительные числа;and in the second subsequence, the condition

where

- numbers of code symbols before interleaving, and

- code symbol numbers after interleaving,

- positive integers;

символов в первую подпоследовательность по первым

адресам, заданным в пилотной псевдослучайной последовательности и производя отбор последних

символов во вторую подпоследовательность по последним

адресам, заданным в пилотной псевдослучайной последовательности, для определения которой формируют множество номеров

от

до

, где

– количество символов для перемежения следующим образом:• - making selection

characters in the first subsequence of the first

addresses specified in the pilot pseudo-random sequence and selecting the latter

characters in the second subsequence of the last

the addresses specified in the pilot pseudo-random sequence, for the determination of which form a set of numbers

from

before

where

- the number of characters to interleave as follows:

, где

– целые положительные числа и выполняется

%;- set the initial value of the parameter explode

where

- positive integers and is satisfied

%;

, определяющих закон взаимно однозначного соответствия между первоначальной последовательностью символов и перемеженной последовательностью символов, состоящее из одной пары чисел, где первое число – номер последовательности до перемежения, а второе число – номер элемента в последовательности после перемежения, где в вышеупомянутой паре чисел первое равно нулю и второе равно случайным образом выбранному номеру из множества

, который при этом исключают из множества

;• form many pairs of numbers

defining the law of a one-to-one correspondence between the initial sequence of characters and the interleaved sequence of characters, consisting of one pair of numbers, where the first number is the number of the sequence before interleaving, and the second number is the number of the element in the sequence after interleaving, where in the aforementioned pair of numbers the first is zero and the second is equal to a randomly selected number from the set

, which is excluded from the set

;

;• initialize

;

элемент

и ставят ему во взаимно однозначное соответствие элемент

, определяя таким образом преобразование

;• randomly selected from a variety of

element

and put him in a one-to-one correspondence element

thus defining the transformation

;

таких, что

,

вычисляют значение

; • perform verification of remote diversity of interleaved symbols for which for all

such that

,

calculate the value

;

, то увеличивают значение

, исключают элемент

из множества

и добавляют в множество

пару

;• if all received values are greater than or equal

then increase the value

exclude element

out of many

and added to many

a couple

;

, то повторно выбирают другой элемент

из множества

и повторяют для него проверку дистанционного разнесения перемеженных символов; • if at least one difference is less than

then re-select another item

out of many

and repeat for him the test of remote diversity of interleaved characters;

;• if it is impossible to find an element that satisfies the check for remote diversity of interleaved characters, repeat the whole algorithm again with the modified diversity parameter

;

присваивают

;• upon reaching a value

appropriate

;

не станет пустым, а множество

не будет содержать

пар чисел;• repeat the procedure until the set

will not become empty, but many

will not contain

pairs of numbers;

• form from the subsequences the final interleaved sequence.

The disadvantage of the prototype is the sequential nature of the interleaving procedure: code symbols can be interleaved only one after another, which will take considerable time, and the advantage of the prototype is good noise immunity characteristics. The prototype is a modification of the S-random [S. Dolinar and D. Divsalar “Weight Distribution for turbo codes using random and non-random permutation” JPL Progress report 42-122 pp 56-65 Aug 15,1995], extended to the case of a short packet length.

The interleaver requirements are to provide sufficient spacing for repeated characters, thereby ensuring the absence or small number of low-weight codewords. There are two classes of interleavers: pseudo-random and deterministic. To generate a random interleaver, a random number sensor is used, with which the number of the interleaved symbol in the sequence after interleaving is determined. The sequence of numbers obtained is checked for sufficiency of diversity of consecutive repeated information symbols with culling (rollback) of sequences that have not passed such a check.

Pseudorandom interleavers require a lot of memory for storage and cannot be generated independently on the receiving and transmitting sides, or such generation will require a lot of computational and time consuming. Deterministic interleavers are free from this drawback, where the method of one-to-one correspondence of interleaving is determined by defining a parameterized algorithm. Such interleavers can be formed on the fly, that is, directly in the decoding process, and are set by determining the parameters of the algorithm (several positive integers).

упорядоченных элементов, сформированных как

подпоследовательностей, где каждая подпоследовательность содержит в среднем

элементов. При этом An example is a solution that is a mutually simple interleaver, [United States Patent 6,857,087 Crozier, et al. February 15, 2005 High-performance low-memory interleaver banks for turbo-codes]. Such a method, known as DRP interleaver, consists in interleaving a sequence

ordered elements formed as

subsequences, where each subsequence contains on average

elements. Wherein

подпоследовательностей для формирования последовательности из

упорядоченных элементов по правилу, установленному в пилотной подпоследовательности, формируя пилотную псевдослучайную подпоследовательность;1. interleave the elements in each of

subsequences to form a sequence of

ordered elements according to the rule established in the pilot subsequence, forming a pilot pseudo-random subsequence;

элементов в пилотной псевдослучайной последовательности из

упорядоченных элементов для формирования перемеженной последовательности, сформированной как

подпоследовательностей, имеющих размер в среднем

элементов;2. interspersed

elements in the pilot pseudo-random sequence from

ordered elements to form an interleaved sequence formed as

subsequences having an average size

elements;

подпоследовательности для получения перемеженной последовательности из

упорядоченных элементов.3. interleave the elements inside each of

subsequences to obtain an interleaved sequence from

ordered items.

, где

количество перемежаемых элементов, а

– старый номер в первой перемеженной последовательности

– число взаимно простое с

. Подобный подход также известен из [S. Dolinar and D. Divsalar “Weight Distribution for turbo codes using random and non-random permutation” JPL Progress report 42-122 pp 56-65 Aug 15,1995] как алгебраический интерливер. Подбор чисел

целесообразно таким образом, чтобы обеспечить наименьшее число кодовых слов с минимальным весом, что так же отвечает критерию минимума циклов длиной 4 на графе Таннера. Данный способ перемежения используют для турбокодов и он неприменим к кодам с низкой плотностью проверок на четность. Однако, взаимно-простой перемежитель допускает параллельное выполнение алгоритма перемежения несколькими процессорами.An essential feature of this method is that step 2 is performed by a mutually simple interleaver corresponding to a transformation of the form

where

the number of interleaved elements, and

- old number in the first interleaved sequence

- the number is coprime with

. A similar approach is also known from [S. Dolinar and D. Divsalar “Weight Distribution for turbo codes using random and non-random permutation” JPL Progress report 42-122 pp 56-65 Aug 15,1995] as an algebraic interleaver. Matching numbers

appropriate in such a way as to ensure the smallest number of code words with minimum weight, which also meets the criterion of minimum cycles of length 4 on the Tanner graph. This interleaving method is used for turbo codes and is not applicable to codes with a low density of parity checks. However, a mutually simple interleaver allows parallel execution of the interleaving algorithm by multiple processors.

In order for the parallel interleaving scheme to be feasible, the operation of each processor should not lead to conflicts when accessing memory. Such conflicts include, for example, an attempt to simultaneously write and read a separate memory cell. The memory is usually implemented in the form of blocks (“banks”) of memory, so that for each block in one time slot, either write access (at the specified address) or read access is possible.

Thus, it is clear that the urgent task is to develop an interleaving algorithm, which, on the one hand, can be implemented as a result of parallel interleaving of a sequence of code symbols by several processors, and, on the other hand, to provide noise immunity characteristics comparable to the prototype.

разбивают на равные подпоследовательности установленного размера

, в каждой из подпоследовательностей производят перемежение по установленному правилу перемежения подпоследовательностей, согласно изобретению, формируют пилотную псевдослучайную подпоследовательность таким образом, что в пилотной подпоследовательности выполняется условие To solve the problem in a method of interleaving a sequence of code symbols, which consists in splitting a sequence of symbols for interleaving into subsequences of symbols for interleaving, exchanging code symbols between and / or within subsequences, forming interleaved subsequences of code symbols, form a final interleaved sequence from subsequences , a sequence of characters to interlace

broken down into equal subsequences of a fixed size

, in each of the subsequences, interleaving is performed according to the established rule of interleaving of subsequences, according to the invention, a pilot pseudo-random subsequence is formed in such a way that the condition is satisfied in the pilot subsequence

, где

– номера кодовых символов до перемежения, а

– номера тех же кодовых символов после перемежения,

– целое положительное число; для определения пилотной псевдослучайной подпоследовательности номеров формируют множество номеров

от

до

, где

– количество символов для перемежения следующим образом: устанавливают начальное целые положительные значение параметра разнесения

, формируют множество пар чисел

, определяющих закон взаимно однозначного соответствия между первоначальной последовательности символов и перемеженной подпоследовательности символов, состоящее из одной пары чисел, где первое число – номер в подпоследовательности до перемежения, а второе число – номер элемента в подпоследовательности после перемежения, где в вышеупомянутой паре чисел первое равно нулю и второе равно случайным образом выбранному номеру из множества

, который при этом исключают из множества

, инициализируют

, случайным образом выбирают из множества

элемент

и ставят ему во взаимно однозначное соответствие элемент

, определяя таким образом, преобразование

, выполняют проверку дистанционного разнесения перемеженных символов для чего для всех

таких, что

,

, вычисляют значение

, если все полученные значения разные, то увеличивают значение

; исключают элемент

из множества

и добавляют в множество

пару

, если хотя бы две разности оказываются равны, то повторно выбирают другой элемент

из множества

и повторяют для него проверку дистанционного разнесения перемеженных символов, при невозможности найти элемент, удовлетворяющий проверке дистанционного разнесения перемеженных символов, повторяют весь алгоритм заново с уменьшенным параметром разнесения

, повторяют процедуру до тех пор, пока множество

не станет пустым, а множество

не будет содержать

пар чисел; формируют перемеженные подпоследовательности, располагая элементы в соответствии с их новыми номерами в каждой подпоследовательности, используя пилотную псевдослучайную последовательность номеров, объединяют перемеженные подпоследовательности в первую перемеженную последовательность, в первой перемеженной последовательности выполняют второе перемежение для чего для каждого символа в последовательности формируют его новый номер в последовательности по порядку путем выполнения преобразования вида

, где

– количество перемежаемых элементов, а

– старый номер в первой перемеженной последовательности,

число взаимно простое с

; формируют вторую перемеженную последовательность, располагая элементы первой перемеженной последовательности в соответствии с новыми номерами, формируют третью перемеженную последовательность, для чего осуществляют преобразование

, где

– последовательность значений из К элементов; формируют финальную перемеженную последовательность, располагая элементы в соответствии с их новыми номерами.

where

- numbers of code symbols before interleaving, and

- numbers of the same code symbols after interleaving,

- a positive integer; to determine the pilot pseudo-random subsequence of numbers form a lot of numbers

from

before

where

- the number of characters to interleave as follows: set the initial integer positive value of the diversity parameter

form a lot of pairs of numbers

defining the law of a one-to-one correspondence between the initial sequence of characters and the interleaved subsequence of characters, consisting of one pair of numbers, where the first number is the number in the subsequence before interleaving, and the second number is the number of the element in the subsequence after interleaving, where in the aforementioned pair of numbers the first is zero and the second is equal to a randomly selected number from the set

, which is excluded from the set

initialize

are randomly selected from the set

element

and put him in a one-to-one correspondence element

thus defining the transformation

perform verification of remote diversity of interleaved symbols for which for all

such that

,

calculate the value

if all the obtained values are different, then increase the value

; exclude element

out of many

and added to many

a couple

, if at least two differences are equal, then select another element again

out of many

and repeat for him the test of remote diversity of interleaved characters, if it is impossible to find an element that satisfies the test of remote diversity of interleaved characters, repeat the whole algorithm again with a reduced diversity parameter

repeat the procedure until the set

will not become empty, but many

will not contain

pairs of numbers; interleaved subsequences are formed by arranging the elements according to their new numbers in each subsequence using a pilot pseudorandom sequence of numbers, the interleaved subsequences are combined into the first interleaved sequence, the second interleaving is performed in the first interleaved sequence, for which for each character in the sequence form its new number in the sequence in order by performing a conversion of the form

where

- the number of interleaved elements, and

- old number in the first interleaved sequence,

the number is coprime with

; form the second interleaved sequence, arranging the elements of the first interleaved sequence in accordance with the new numbers, form the third interleaved sequence, for which the conversion

where

- a sequence of values from K elements; form the final interleaved sequence, arranging the elements in accordance with their new numbers.

The proposed method of interleaving a sequence of code symbols is as follows:

• break the sequence of characters for interleaving into subsequences of characters for interleaving;

• exchange code symbols between and / or within subsequences, forming interleaved subsequences of code symbols;

• form the final interleaved sequence from subsequences;

разбивают на равные подпоследовательности установленного размера

;• a sequence of characters to interleave the number

broken down into equal subsequences of a fixed size

;

, где

– номера кодовых символов до перемежения, а

– номера тех же кодовых символов после перемежения,

– целое положительное число;• in each of the subsequences, interleaving is performed according to the established rule of alternating subsequences, for this a pilot pseudo-random subsequence is formed in such a way that the condition is satisfied in the pilot subsequence

where

- numbers of code symbols before interleaving, and

- numbers of the same code symbols after interleaving,

- a positive integer;

от

до

, где

– количество символов для перемежения следующим образом:• to determine the pilot pseudo-random subsequence of numbers, multiple numbers are generated

from

before

where

- the number of characters to interleave as follows:

, формируют множество пар чисел

, определяющих закон взаимно однозначного соответствия между первоначальной последовательностью символов и перемеженной подпоследовательностью символов, состоящее из одной пары чисел, где первое число – номер в подпоследовательности до перемежения, а второе число – номер элемента в подпоследовательности после перемежения, где в вышеупомянутой паре чисел первое равно нулю и второе равно случайным образом выбранному номеру из множество

, который при этом исключают из множества

;set the initial integer positive value of the diversity parameter

form a lot of pairs of numbers

defining the law of one-to-one correspondence between the initial sequence of characters and the alternated subsequence of characters, consisting of one pair of numbers, where the first number is the number in the subsequence before interleaving, and the second number is the number of the element in the subsequence after interleaving, where in the above pair of numbers the first is zero and the second is equal to a randomly selected number from the set

, which is excluded from the set

;

;• initialize

;

элемент

и ставят ему в взаимно однозначное соответствие элемент

, определяя таким образом преобразование

;• randomly selected from a variety of

element

and put him in a one-to-one correspondence element

thus defining the transformation

;

таких, что

,

вычисляют значение

; • perform verification of remote diversity of interleaved symbols for which for all

such that

,

calculate the value

;

, исключают элемент

из множества

и добавляют в множество

пару

;• if all received values are different, then increase the value

exclude element

out of many

and added to many

a couple

;

из множества

и повторяют для него проверку дистанционного разнесения перемеженных символов; • if at least two differences are equal, then re-select another element

out of many

and repeat for him the test of remote diversity of interleaved characters;

;• if it is impossible to find an element that satisfies the check for remote diversity of interleaved characters, repeat the whole algorithm again with a reduced diversity parameter

;

не станет пустым, а множество

не будет содержать

пар чисел;• repeat the procedure until the set

will not become empty, but many

will not contain

pairs of numbers;

• form interleaved subsequences by arranging the elements in accordance with their new numbers in each subsequence using a pilot pseudo-random sequence of numbers;

• combine interleaved subsequences into the first interleaved sequence;

, где

– количество перемежаемых элементов, а

– старый номер в первой перемеженной последовательности,

– число взаимно простое с

;• in the first interleaved sequence, the second interleaving is performed, for which, for each character in the sequence, form its new number in the sequence in order by performing a transformation of the form

where

- the number of interleaved elements, and

- old number in the first interleaved sequence,

- the number is coprime with

;

• form the second interleaved sequence, arranging the elements of the first interleaved sequence in accordance with the new numbers;

-го элемента, начиная с первого, получают новый номер во второй перемеженной последовательности, где новый номер равен

, при этом номера остальных элементов последовательности не изменяют;• for everybody

-th element, starting from the first, get a new number in the second interleaved sequence, where the new number is

, while the numbers of the remaining elements of the sequence do not change;

, где

последовательность значений из К элементов;• form the third interleaved sequence, for which the conversion is carried out

where

a sequence of values from K elements;

• form the final interleaved sequence, arranging the elements in accordance with their new numbers.

The proposed method of alternating a sequence of code symbols can be implemented on a digital signal processor, an array of digital signal processors, FPGAs, on a specialized chip. The interleaving algorithm is shown in FIG. 7.

Consider the algorithm as an interleaving algorithm in a rectangular interleaver. The essence of the algorithm is that in the first stage of interleaving, interleaving is performed inside each of the subsequences or interleaving in each row, and in the second stage, mutually simple interleaving, in the third, a cyclic shift in the columns. All three operations can be carried out in parallel.

Distinctive (new) features of the proposed method of data transmission in a digital radio communication system relative to the prototype are the following features:

- A new way of interleaving code symbols;

-new method of code pairing packages;

A new way to decode code-conjugate packets.

A comparative analysis of the proposed methods with the prototype shows that the present invention is significantly different from the known solutions, as it allows to improve the quality of radio communications by reducing the number of redundant code symbols transmitted by code pairing packets with automatic request-repetition, as well as using a new optimized interleaving methods, increase the speed and throughput of the device - due to the parallel processing of data packets.

Thus, the technical result consists in obtaining an energy gain of encoding of an average of 0.5 dB, as well as in simplifying the search for a pseudo-random sequence of alternation of code symbols.

To this end, the method uses code pairing of packets and a new method of interleaving code symbols.

Thus, the claimed method allows to achieve an energy gain of coding on average 0.5 dB compared with the prototype. In addition, the inventive method can significantly simplify the search for a pseudo-random sequence of alternation of code symbols, and also allows the parallel implementation of a decoding device without loss of noise immunity characteristics.

Claims (7)

1. A method of transmitting data in a digital communication system, which consists in the fact that data packets are formed on the transmitting side, each of which contains an ordered sequence of information symbols, each information symbol is repeated a certain number of times, depending on its number in order in the sequence of symbols, forming a sequence of repeated information symbols, and the number of repetitions is determined in advance, interleave in the sequence of repeated information symbols tins, achieving sufficient diversity of consecutive repeated information symbols and forming a sequence of interleaved repeated information symbols, divide the interleaved repeated information symbols into groups so that the first verification symbol is obtained by summing, according to a given module, the initial value of the summation variable with all interleaved repeated information symbols from the first groups, and the verification symbol n - by summing over a given module of the verification symbol n -1 with all interleaved repeated information symbols from group n , remember the received verification symbols, form a code word by adding verification symbols to information symbols, received correlation responses to each of the transmitted code symbols are generated on the receiving side, estimate the noise parameter of the signal mixture plus noise, form soft decisions about the received code symbols using the obtained estimate of the noise parameter of the signal plus noise mix soft decisions about code symbols for information symbol decisions and verification symbol decisions, repeat soft information symbol decisions in accordance with the information symbol repetition pattern, repeat soft verification symbol decisions at least two times with the exception of the last verification symbol, for soft information decisions symbols perform interleaving similar to interleaving on the transmitting side, form groups of interleaved soft decisions about information symbols, similar to groups m respective information symbols on the transmitting side, a first group of interleaved soft decisions complement soft decision corresponding to the initial value of the summation variable, and the first copy of the soft decision on the first parity symbol, forming a first codeword code generalized parity check, n - th group of interleaved soft decisions complemented by a second copy of the (n -1) - th parity and the first copy of a soft decision on n - m of check symbols to form n - e codeword generalized checks chetnos code then, for each soft decision included in each code word of the generalized parity check code, a modified soft solution is formed, which is an outgoing message of the code word of the generalized parity check code so that the outgoing message of the code word of the generalized parity check code is the result functional transformation of the original soft decisions, which are incoming messages of the code word of the code of the generalized parity check, deinterleave the outgoing community code word of the generalized parity check code so that each copy of the soft decision on the code symbol is associated with an outgoing message of the code word of the general parity code corresponding to the copy of the soft decision on this symbol, outgoing messages of the code word of the general parity code are grouped with soft decisions about the accepted code symbols, so that each group includes a soft decision about the corresponding code symbol and an outgoing message of the code word of the code generalized a parity check corresponding to a copy of the soft decision about this symbol, thus forming a code word for a generalized repeat code, putting each code word for a generalized repeat code in correspondence with a code symbol so that each outgoing message of a code word for a generalized parity code is an incoming code message words of the generalized repetition code, for each soft decision included in each codeword of the generalized repetition code, form a modified soft solution, cat A swarm is an outgoing message of a generalized code of a repeat code, which is the result of a functional transformation of an incoming code word of a code of a generalized repetition code, iteratively repeat the process of exchanging outgoing and incoming messages so that the outgoing message of a code word of a generalized repetition code is an incoming message of a code word of a generalized verification code for parity, and the outgoing message of the generalized parity check code is an incoming code message word of the generalized repetition code, forming a sequence of modified soft decisions at each iteration, decoded code words are formed from a sequence of modified soft decisions, each decoded code word is multiplied by a verification matrix, getting an ordered sequence of checksums, if all the checksums are zero, then the code word consider decoded correctly if the number of checksums other than zero is odd and the last checksum is nonzero, t replace it with zero, if the number of checksums other than zero is odd and the last checksum in the sequence is zero, then it is replaced with any nonzero value, the sequence of checksums is divided into pairs that contain elements of the sequence in a row, each the checksum is included only in a single pair, in each pair the difference in the numbers of the checksums is calculated, all the received differences in the numbers of the checksums are added, the received number is compared with the specified threshold m, if the number exceeds the set threshold, then the information part of the code word is considered decoded incorrectly, if the received number is less than the specified threshold, then the information part of the code word is considered decoded correctly, characterized in that if the information part of the code word is decoded incorrectly, then the request signal is repeated feedback channel for the transmitting side, on the transmitting side upon receipt of the retransmission request signal form a packet with a code-conjugate part, for which in the next encoded packet, part of the code symbols is replaced by a modulo-two sum with the code symbols of a previously transmitted and erroneously decoded packet, thereby forming a code-conjugate part; upon receipt of the current packet with a code-conjugate part, it is decoded together with the previously received erroneously decoded packet, for which restore, possibly with errors, the sequence of soft decisions of the erroneous package, modify soft decisions in the code-conjugate part in those positions in which the code characters were replaced by the sum of symbols of different packets, for which they replace the opposite sign of the adopted soft decision, if the recovered code symbol of the previous packet corresponds to a logical unit, receiving soft solutions of the current package, decode soft solutions of the current package, restore the sequence of soft solutions of the current package, modify soft solutions in the code-conjugate part in those positions in which the code symbols were replaced by the sum of the symbols of different packets, for which the sign is replaced with the opposite for the received one soft decision, if the recovered code symbol of the current packet corresponds to a logical unit, receiving a modified sequence of soft decisions for the erroneous packet, re-decode the error packet using the modified sequence of soft decisions for the erroneous packet as additional information at those positions in which the code symbols were replaced by the sum of different symbols packets transmit on the feedback channel signals characterizing the decoding performance of code-conjugate packets ov. 2. The method according to p. 1, characterized in that the estimate of the noise parameter of the signal plus noise mixture is determined as the standard deviation of the equivalent Gaussian white noise, which approximates the noise in the channel. 3. The method according to p. 1, characterized in that iterative decoding is performed in parallel, processing messages in each of the code words of the generalized repetition code or code words of the generalized parity check code independently of each other, and the message exchange procedure between control and variable vertices carry out once per iteration. 4. The method according to p. 1, characterized in that iterative decoding is performed in sequential mode, sequentially processing the messages in the code words of the generalized repetition code and the code words of the generalized parity check code, at least one outgoing message from the processed code word of one code is an incoming message for a codeword of another code. 5. The method according to p. 1, characterized in that iterative decoding is performed in serial-parallel mode, highlighting among the whole set of code words of codes of a generalized repetition code and a code of generalized parity, a subset of code words processed in parallel and a subset of code words, processed in sequential mode. 6. A method of interleaving a sequence of code symbols, which consists in splitting a sequence of symbols for interleaving into subsequences of symbols for interleaving, exchanging code symbols between and / or within subsequences, forming interleaved subsequences of code symbols, forming from the subsequences a final interleaved sequence, a sequence of characters to interleave the number N is divided into equal subsequences of a fixed size K , in each of the subsequences, interleaving is performed according to the established rule of interleaving of subsequences, characterized in that a pilot pseudo-random subsequence is formed in such a way that the condition is satisfied in the pilot subsequence

, where i , j _1,2 are the code symbol numbers before interleaving, and

- numbers of the same code symbols after interleaving, S is a positive integer; to determine the pilot pseudo-random subsequence of numbers, a set of numbers M is formed from 0 to K -1, where K is the number of characters to interleave as follows: set the initial integer positive values of the diversity parameter S , form a set of pairs of numbers Θ that determine the law of one-to-one correspondence between the initial sequence characters and interleaved subsequence of characters, consisting of one pair of numbers, where the first number is the number in the subsequence before interleaving, and T the next number is the number of the element in the subsequence after interleaving, where in the aforementioned pair of numbers, the first is zero and the second is a randomly selected number from the set M, which is excluded from the set M, i = 1 is initialized, and the element i is randomly selected from the set M _n and put in one-to-one correspondence the element i , thus defining the transformation

, check remote diversity of interleaved symbols, for which, for all j such that j < i ,

calculate the value

if all the obtained values are different, then increase the value i = i +1; exclude the element i _П from the set M and add to the set Θ the pair i, i _П , if at least two differences are equal, then select another element again

from the set M and repeat the check for remote diversity of interleaved symbols for it, if it is impossible to find an element that satisfies the verification of remote diversity of alternated symbols, repeat the whole algorithm again with a reduced diversity parameter S , repeat the procedure until the set M becomes empty, and the set Θ will not contain K pairs of numbers; interleaved subsequences are formed by arranging the elements according to their new numbers in each subsequence using a pilot pseudorandom sequence of numbers, the interleaved subsequences are combined into the first interleaved sequence, the second interleaving is performed in the first interleaved sequence, for which a new number is generated for each character in the sequence sequences in order by performing a conversion of the form

where N is the number of interleaved elements, and i _old is the old number in the first interleaved sequence, p is a number coprime to N ; form the second interleaved sequence, arranging the elements of the first interleaved sequence in accordance with the new numbers, form the third interleaved sequence, for which the conversion

where Q is a sequence of values from K elements; form the final interleaved sequence, arranging the elements in accordance with their new numbers.

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