RU2264647C1 - Method for adaptive information transfer - Google Patents

Abstract

FIELD: information transfer technologies.

SUBSTANCE: in the method, via channel with non-zero conductive ability a set of M stochastic (n,k,q) codes is used with correction of errors with guaranteed in any channel upper limit of decoding error possibility due to use for all codes of same code base q, each of codes is optimal for certain quality of channel, prior to information transfer conductive ability of channel is checked by transferring testing set, in form of q-base stochastic (n,1,q) code, conductive ability of channel is determined by pair-wise comparison of q-based symbols of received block of (n,1,q) code and counting number of matching symbols N, parameters n and k of optimal (n,k,q) code are selected with correction of errors, information exchange is performed by code blocks of selected code with correction of errors and detection of blocks with error repetition factor exceeding correcting ability of code, blocks are transferred again with uncorrected errors, share of blocks with uncorrected errors is calculated within range of analysis with length G of last received blocks, compliance of this share to range of optimality criterion of effective code is checked on basis of current state of channel, on exit beyond limits of code optimality code parameters n and k and checking matrix H are altered synchronously for sending and receiving sides of channel.

EFFECT: higher speed of operation, higher resistance to interference, higher trustworthiness, higher efficiency.

Description

The invention relates to technical means of noise-immune transmission and protection of information on communication channels and networks and can be used in channels and networks of various types.

Known methods for transmitting information over communication channels using error-correcting cyclic codes with error detection as part of the data transmission channel (COP) protocols in which the transmitted information is encoded with a cyclic code, received in the form of blocks of a cyclic code is checked for distortions, distorted blocks are retransmitted by signal feedback. These methods have three main disadvantages:

- with a decrease in the quality of the discrete communication channel, transmission becomes impossible, since a large number of received blocks are distorted and the efficiency (loops),

- the KPD does not provide comprehensive information protection, additional technical solutions are used to protect against the imposition of false information and cryptographic protection,

- the error detection mode of cyclic codes does not provide an effective transmission rate close to the bandwidth of the communication channel.

Known methods for transmitting information using algebraic codes with error correction (Hamming codes, Bowes-Chowdhury-Hawkingham, Reed-Solomon, etc.). These methods have the following disadvantages:

- algebraic codes in the error correction mode turn out to be very sensitive to the error multiplicity, which leads to a large and uncontrolled probability of decoding errors in channels with grouping errors, which takes place in real communication channels;

- coding and especially decoding of known codes has a relatively complicated implementation, especially in the case of a software implementation.

The aim of the invention is to provide stable exchange of information over a channel with unknown prior to the quality parameters to achieving effective transmission speed close to the capacity of the communication channel with guaranteed in any channel reliability, the estimated probability of an error in the information issued by the user P _err ≤R _mp. where R _tr. - the required upper limit of the probability of error.

To achieve this goal, it is necessary to use error-correcting code with the following set of properties:

- providing a guaranteed probability of decoding errors in an arbitrary communication channel;

- the presence of such a set of parameters (code length n, the number of information symbols k and the number of correctable errors t) that would be optimal in channels of very low quality (with a probability of distortion of the binary symbol P _{0 of the} order of 10 ^-1 ), low (with P _{0 of the} order 10 ^-2 ), medium (at P _{0 of the} order of 10 ^-3 ), high (at P _{0 of the} order of 10 ^-4 ) and very high (at P _{0 of the} order of 10 ^-5 ) quality;

- the code must have parameters to ensure reliable testing of an unknown communication channel so that the test sequence is reliably and reliably transmitted with any channel quality.

As such a code, it is proposed to use a stochastic q-ary (n, k, q) error correction code based on a binary (n, k) code with a code distance d and l-interleaving, where q = 2 ^l . Such a code makes it possible to correct t = d-2 distorted q-ary characters while providing the upper limit of the decoding error P _Osh. ≤q ^-1 . This code has a set of code parameters that have the necessary properties. For channel testing, a code with the repetition of (n, 1, q) can be used at n of the order of 50-100. For channels of different quality, for example, the following set of codes can be used:

- at Р _{0 of the} order of 10 ^-1 - code (8.2, q);

- at Р _{0 of the} order of 10 ^-2 - the code (8.4, q);

- at Р _{0 of the} order of 10 ^-3 - code (16.11, q);

- at Р _{0 of the} order of 10 ^-4 - code (32.26, q);

- at Р _{0 of the} order of 10 ^-5 - code (128,120, q);

- at Р _{0 of the} order of 10 ^-6 - code (512,502, q).

In accordance with the invention, in the method of complex information protection, it is proposed to build as follows.

For adaptive transmission of information over a channel with a nonzero bandwidth, a set of M stochastic (n, k, q) codes is used with error correction for the decoding error probability guaranteed by an arbitrary channel due to the use of the same code base q for all codes, each codes is optimal for a certain quality of the channel, before transmitting information, check the channel capacity by transmitting a test sequence in each direction before Achi in the form of a q-ary stochastic (n, 1, q) code determines the channel capacity by pairwise comparing the q-ary characters of the received block (n, 1, q) code and counting the number of matching N characters, select the parameters n and k optimal (n, k, q) code with error correction, exchange information with code blocks of the selected code with error correction and detection of blocks with an error rate exceeding the correcting ability of the code, repeat the transmission of blocks with uncorrected errors, calculate the proportion of blocks with uncorrected errors n analysis interval length G recently received blocks, check the conformity of this share interval optimality criterion existing code to the current state of the channel, at the exit of the share beyond the optimal code change synchronously to the transmitting and receiving sides of the channel code parameters n and k and parity matrix H.

Moreover, a set of M stochastic error-correcting codes includes codes that ensure stable exchange with the maximum allowable speed for channels of very low quality, low, medium, high and very high quality.

In duplex communication channels, the quality of each direction of transmission is separately checked and the optimal code for each direction of transmission A and B is selected, the number of the selected code is transmitted to the opposite side of the duplex channel, the code is the same for both directions of transmission, which is more noise-resistant from the codes for A and B.

When exchanging information for a previously selected code, the optimality of the applied code is monitored, for which cases of refusal to correct errors by the applied code are recorded, the number of cases of refusal to correct errors N _from the interval of the analysis channel with the length G of the last received blocks is calculated, and after the next refusal to correct fraction as a failure _of α = N / G, check code optimality conditions used in a ratio β _min ≤α≤β _max, in the case of β _min ≥α decision about the operating code to replace mene Immunity at α≥β _max taken the decision to replace the existing code more robust.

To analyze the optimality of the code, the fraction of blocks with uncorrected errors α is calculated on the analysis interval with the length G of the last received blocks after fixing another case of refusal to correct errors by storing G decoding results of blocks, and in the absence of decoding refusal, write the symbol 0 in the cell of the last block with the number i, in case of refusal to decode - symbol 1, the decoding result of the block with number (iG) is excluded from the analysis, the number of units N _from in G cells is calculated.

бит (q=2^l), причем значение длины такого символа выбирается исходя из требуемой достоверности, описываемой вероятностью ошибки декодирования Р_ош, причем при выбранном q имеет место соотношение Р_ош≤q^-1, например, для обеспечения Р_ош=10^-9 можно использовать значение

=32 бита. Важно, что в соответствии со способом можно обеспечивать любую достоверность, конструктивно устанавливаемую при проектировании гарантированную в произвольном канале связи. Так при

=64 обеспечивается Р_ош≤q^-1=10^-18 и т.п.When implementing the method, after determining the channel capacity and the optimal parameters of the stochastic code, the information to be protected is divided into q-ary characters of length

bit (q = 2 ^l), wherein the length of the symbol selected based on the desired reliability described decoding error probability P _err, q being selected at the relation F _oui ≤q ^-1, for example, for P = 10 ^-9 _oui can use value

= 32 bits. It is important that in accordance with the method it is possible to provide any reliability that is constructively set during design and guaranteed in an arbitrary communication channel. So with

P = 64 is provided _oui ≤q ^-1 = 10 ^-18, etc.

от независимого датчика, на приемной стороне выполняют обратное стохастическое каждого q-ичного символа с участием синхронно вырабатываемых значений ξ длиной

, выполняют локализацию правильно принятых q-ичных символов, подсчитывают число локализованных символов, проверяют правильность локализации, недостоверно локализованные символы стирают, нелокализованные и стертые символы исправляют, выражая значения исправляемых символов через значения достоверно локализованных символов.For each k q-ary symbols, nk redundant q-ary symbols are generated according to the rules of the binary (n, k) code, before being transmitted to the communication channel, each q-ary symbol is subjected to stochastic transformation with the participation of the transformation parameter ξ of length

from an independent sensor, on the receiving side, the opposite stochastic of each q-ary symbol is performed with the participation of synchronously generated values of ξ of length

, localize correctly received q-ary characters, count the number of localized characters, check the correctness of localization, unreliably localized characters are erased, non-localized and erased characters are corrected, expressing the values of corrected characters through the values of authentically localized characters.

выполняют с помощью регистра с нелинейными функциями в цепях обратной связи на основе таблиц со случайным заполнением. При этом при реализации способа начальное заполнение таблиц случайными числами и регистра сдвига с обратной связью являются ключом криптографической защиты.In this case, stochastic transformation is performed using operations based on tables with random filling. Generation of transformation parameter ξ with length

performed using a register with non-linear functions in the feedback circuits based on tables with random filling. Moreover, when implementing the method, the initial filling of tables with random numbers and a shift register with feedback are the key to cryptographic protection.

Stochastic transformation is a cryptographic operation that provides:

- on the transmitting side, when transmitting any information, even the same information combinations in the code block, the transition to random signals in the communication channel, which ensures absolute secrecy in Shannon’s production;

бит преобразование его с одну из 2^l-1 случайных комбинаций (кроме переданной) с равной вероятностью, что обеспечивает получение гарантированной в произвольном канале достоверности Р_ош≤q^-1. Таким образом может быть получена любая (выбором значения

) необходимая достоверность, в том числе и стремящаяся к нулю.- on the receiving side - within each distorted q-ary character of length

bit converting it to one of the 2 ^l -1 random combinations (except transferred) with equal probability, that provides guaranteed in any channel reliability F _oui ≤q ^-1. Thus, any can be obtained (by choosing a value

) necessary reliability, including tending to zero.

The described method has the following advantages:

1) provides a stable exchange of information on the channel with unknown characteristics; sufficient for the exchange of information using this method is the nonzero bandwidth of the provided channel, that is, the presence of connectivity or the ability to transmit information;

2) provides the maximum effective data transfer rate for a given channel, close to the channel capacity;

3) through the use of a set of M stochastic codes with error correction, the advantages arising from the properties of these codes are achieved, namely:

- ensuring comprehensive protection within the framework of a single set of information processing operations for once introduced redundancy;

- increase the efficiency of information processing with the achievement of:

- guaranteed reliability in error correction mode with an arbitrary nature and intensity of distortion in the communication channel,

- increase in the effective speed of information transfer,

- providing real time;

4) a high speed of information processing is achieved, not restraining the physical speed in the communication channel, expressed in bits per second;

5) high cryptographic strength is ensured in protecting information by achieving the following properties:

- after encryption and before issuing a quasi-random sequence of signals to the communication channel, regardless of the statistics of individual letters in the source text;

- the use of a complex transformation that does not have any other formal description, except for the description of filling in random conversion tables;

- the ability to consider the initial filling of random tables as an encryption key;

6) widespread use of error-correcting codes with direct code error correction in channels with an arbitrary distribution law and error rate in a communication channel, including with deliberate distortions with the aim of destructive effects on communication channels and communication networks and information systems.

The method can be used in all cases where error-correcting codes are used with error detection and correction, cryptography methods, means of protection against imposing false information, moreover, as in cases when the protection is built as complex (in tunneled protocols and special-purpose systems), and in cases where some of the tasks of integrated protection have traditionally been used. That is, the method can be applied in:

6) networks like Intemet / Inranet;

7) in radio networks and communication channels;

8) in operating systems and databases;

9) mobile telephone networks;

10) in the applied software of information systems and control systems.

Sources of information

1. W. Peterson, E. Weldon. Error correction codes. M., World, 1976.

2. Winter V.M., Moldovyan A.A., Moldovyan N.A. Global network technology security. - SPb .; BHV-Petersburg, 2001.

3. GOST 28147-89. Information processing systems. Cryptographic protection. Cryptographic conversion algorithm. - M.: Civil Code of the USSR by standards, 1989.

4. Romanets Yu.V., Timofeev PA, Shangin V.F .. Information security in computer systems and networks. - M .: Radio and communications, 1999.

5. Moscow University and the development of cryptography in Russia. Materials of the conference at Moscow State University 17-18, 2002 - M .: ICMMO, 2003. - 287 p.

Claims (5)

1. A method for adaptively transmitting information over a channel with a nonzero bandwidth, characterized in that a set of M stochastic (n, k, q) codes is used with error correction for the decoding error probability guaranteed by an arbitrary channel due to the use for all codes the same basis of the q code, each of the codes provides the maximum speed for a certain channel quality, which is an optimality criterion for this channel quality, the degree of optimality is determined as up to I received the blocks with the refusal to correct errors, first check the channel bandwidth before transmitting the information by transmitting the test sequence in each direction of transmission in the form of a q-ary stochastic (n, l, q) code, determine the channel bandwidth by pairwise comparison q different characters of the received block (n, l, q) code and counting the number of matching characters N, select the parameters n and k of the optimal (n, k, q) code with error correction, exchange information with the code blocks of the selected code with correction m errors and detecting blocks with error rates exceeding the correcting ability of the code, repeat the transmission of blocks with uncorrected errors, calculate the fraction of blocks with uncorrected errors on the analysis interval with the length G of the last received blocks, check the correspondence of this fraction to the interval of the optimality criterion of the current code for the current state of the channel, the output of this fraction beyond the limits of code optimality is changed synchronously for the transmitting and receiving sides of the channel, the parameters of the code n and k and its verification matrix N. 2. The method according to claim 1, characterized in that the set of M stochastic error correction codes includes codes that ensure stable exchange with the maximum allowable speed for channels from low quality to high quality. 3. The method according to claim 1, characterized in that the quality of each transmission direction is separately checked in duplex communication channels and the optimum code for each transmission direction A and B is selected, the number of the selected code is transmitted to the opposite side of the duplex channel, and the same for both transmission directions is selected code that is the more noise-resistant of the codes for A and B. 4. The method according to claim 1, characterized in that for the current control of the optimality of the applied code, cases of refusal to correct errors by the applied code are recorded, the number of cases of refusal to correct errors N _from the interval of the analysis channel with the length G of the last received blocks is calculated after the next refusal corrections calculate the failure rate as α = N _of / G. 5. The method according to claim 1, characterized in that the proportion of blocks with uncorrected errors α is calculated on the analysis interval with a length G of the last received blocks after fixing another case of failure to correct errors by storing G decoding results of blocks, and in the absence of decoding failure, write a symbol 0 to the cell of the last block with the number i, in case of decoding failure - symbol 1, the decoding result of the block with the number (iG) is excluded from the analysis, the number of units N _from in G cells is calculated.