RU2239289C2 - Method for transmitting digital information in feedback systems - Google Patents

Abstract

FIELD: radio and electrical communications, computer engineering.

SUBSTANCE: on sending end of communication line input signal is divided into n-bit blocks, message is formed from series of several blocks, formed message is stored and transferred twice; on receiving end of communication line message is stored upon first reception and then compared with second message upon its reception; information for further transfer of next messages is transmitted over feedback channel in case those received coincide or information about retransfer of messages over feedback channel is sent, if twice received messages do not coincide; in the process on sending end second of transferred messages is coded by modulo P = 2 ⁿ addition of each character α ₁ corresponding to this block with coded character β _i-1 of preceding block; on receiving end retransferred message is decoded by modulo P addition of next received character β _i , messages with preceding conjugate character β* _i-1 of this message, α _i ≡ β _i + β* _i-1 (modulo P), where β* _i-1 = P - β _i-1 ; characters of first received message are compared with those of retransferred and decoded message, and if two adjacent characters of messages coincide, all incorrect characters of first received message are replaced by characters of decoded message; if two adjacent characters of first received message and decoded one do not coincide, incorrect characters are corrected, and information for further transmission of next messages is transferred over feedback channel; if three or more adjacent characters of first received message and decoded one do not coincide, information for retransmission of formed message is transferred over feedback channel.

EFFECT: enhanced information transfer speed in heavy noise environment.

3 cl, 3 dwg

Description

The invention relates to the field of radio communications, telecommunications and computer technology, and more particularly to the field of methods and devices for transmitting information in computer networks.

Known methods for transmitting discrete information in feedback systems (see, for example, [1] p. 395-427, [2], patent application No. 99123808/09 from 10.11.1999 [3]).

In the known methods in the presence of distortion of information using retransmission of messages. In this case, either the received messages (systems with informational feedback) or the decision on the correct or erroneous reception of messages (systems with crucial feedback) are transmitted via the feedback channel. The use of feedback provides high reliability of the transmitted information.

In feedback systems, redundancy depends on the real signal-to-noise ratio and is random, since it is introduced as errors occur. In this regard, ceteris paribus, the redundancy in feedback systems can be significantly less than the redundancy introduced in each code combination to detect and correct errors and sufficient for a given reliability of information transmission [1].

Closest to the technical nature of the claimed method is the method described in [1] p. 420-421. The method includes dividing the input signal into blocks of n-bit length at the transmitting end of the communication line, generating a message in the form of a sequence of several blocks, storing and transmitting the generated message twice, and storing the message after the first reception and reconciling messages after the second reception at the receiving end of the communication line , transmitting information on the feedback channel to continue transmitting subsequent messages, if the received messages match, transmitting information on the feedback channel for retransmission I receive messages if twice received messages do not match.

However, the prototype method has a drawback. In the presence of strong interference in the communication line and with active intrusions, the information transfer rate decreases sharply, since the average number of transmissions of each message increases, which ensures the required reliability of communication.

Thus, the invention solves the problem of increasing the speed of information transfer in conditions of strong interference.

этого сообщения,

(mod Р), где

сравнивают символы первоначально принятого сообщения с символами повторно принятого декодированного сообщения, при этом, если нет расхождений в двух смежных символах сообщений, то заменяют все одиночные искаженные символы первоначально принятого сообщения на символы декодированного сообщения, а если имеются расхождения в двух смежных символах первоначально принятого и декодированного сообщения, то кодируют скорректированное первоначально принятое сообщение аналогично как и на передающем конце линии связи, сравнивают его с принятым закодированным сообщением, заменяют два искаженных символа первоначально принятого сообщения на символы декодированного сообщения, если возникли расхождения во всех последующих символах сравниваемых закодированных сообщений и передают по каналу обратной связи информацию на продолжение передачи последующих сообщений, а если возникли расхождения в трех и более смежных символах первоначально принятого и декодированного сообщений, то передают по каналу обратной связи информацию на повторную передачу сформированного сообщения.This is achieved by the fact that in the known method of transmitting discrete information in feedback systems, which consists in dividing the input signal into blocks of n-bit length at the transmitting end of the communication line, forming a message in the form of a sequence of several blocks, storing and transmitting the generated message twice, and at the receiving end of the communication line, storing the message after the first reception and reconciling messages after the second reception, transmitting information on the feedback channel to continue transmitting subsequent messages messages, if the received messages match, transmitting information on the feedback channel for retransmission of messages if the twice received messages do not match, according to the invention, at the transmitting end of the communication line, the second of the transmitted messages is encoded by modulo P = 2 ⁿ each symbol a _i corresponding to this block, with the encoded symbol β _{i-1 of the} previous block, β _i ≡ β _i-1 + a _i (mod Р), and at the receiving end of the communication line, the re-received message is decoded by adding modulo Р the next received symbol β _i Messages with a previous conjugate character

this message

(mod P), where

comparing the characters of the originally received message with the characters of the re-received decoded message, in this case, if there are no discrepancies in the two adjacent message characters, then replace all the single distorted characters of the originally received message with the characters of the decoded message, and if there are discrepancies in the two adjacent characters of the originally received and decoded messages, then encode the adjusted originally received message in the same way as at the transmitting end of the communication line, compare it with received m encoded message, replace two distorted characters of the originally received message with the characters of the decoded message if there are discrepancies in all subsequent characters of the compared encoded messages and transmit information on the feedback channel to continue transmitting subsequent messages, and if there are discrepancies in three or more adjacent characters initially received and decoded messages, then transmit feedback information on the retransmission of the generated message.

In the aggregate of the features of the claimed method, the following terminology and notation are used:

- discrete information is messages or data written in binary code and represented by a signal in the form of a sequence of zero and single bits;

- a symbol is a number written in the form of signs of a binary number system and presented in the form of a sequence (combination) of zero and single bits;

≡ is the comparability ratio (a = b (mod p)) - a is comparable with b modulo p: two numbers a and b are called comparable modulo p if their residues are equal when dividing both numbers by p;

- the addition of the numbers a and b modulo p means that the two numbers are added in the usual way, and their sum is translated into a finite set by comparison modulo p.

These distinctive features in comparison with the prototype allow us to conclude that the proposed technical solution meets the criterion of "novelty."

In the proposed method for transmitting discrete information in feedback systems, the listed set of essential features in the indicated order ensures a high speed of information transfer, since the average number of transmissions of each message is reduced, because for the used method of encoding message symbols when one of the encoded symbols is distorted, the error when decoding a message, it extends to the adjacent character. If one of the encoded characters is distorted, the error when encoding the message extends to the entire length of the message and all subsequent characters of the encoded message will be distorted. These properties of the used code allows not only detecting distorted characters in transmitted messages, but also correcting distorted characters when receiving encoded and non-encoded messages.

It is a new property of a set of features that lead to an increase in the speed of information transfer in feedback systems under conditions of strong interference and active intrusions, which allows us to conclude that the proposed technical solution meets the criterion of "inventive step".

The proposed method for transmitting discrete information in feedback systems has been tested in the laboratory. An example implementation of this method using devices is presented in figure 1, where:

block 1 - signal source;

block 2 - the first storage device;

block 3 - encoding device;

block 4 - the first transmitter;

block 5 - the first receiver;

block 6 - the second receiver;

block 7 - the second storage device;

block 8 - decoding device;

block 9 - a decisive device;

block 10 - the second transmitter.

Encoding and decoding devices can be implemented using a computer or using separate devices.

Figure 2 presents a block diagram of an encoder, where block 11 is an adder modulo P, and block 12 is a delay line for one symbol, and figure 3 presents a block diagram of a decoding device, where block 13 is a subtractor, block 14 is a delay line for one symbol, and block 15 is an adder modulo R.

Signal in the form of a sequence of zero and single bits

{1110000010000110001010011110100011100100101101110110011010101111}

divided into blocks. For simplicity, the description of the operation of the device, we assume that the block length is n = 3 bits. In this case, P = 2 ⁿ = 8, and the sequence of blocks will have the form

{111 000001 000011 000 101 001 111 010001 110010010 110 111 011 001 101 010 111}.

(mod P), где

. В решающем устройстве 9 символы декодированного сообщения {7, 0, 1, 0, 3, 0, 5, 1, 7, 2, 1, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7} сравнивают с символами первоначально принятого сообщения, хранящимися во втором запоминающем устройстве 7. Если отсутствуют расхождения в символах, то с помощью устройств 10 и 5 передают на другой конец линии связи информацию на продолжение передачи последующих сообщений. Если есть расхождения в сравниваемых символах, то осуществляют корректировку искаженных символов. При этом заменяют все искаженные символы первоначально принятого сообщения на символы декодированного сообщения, если нет расхождений в двух смежных символах. Если имеются расхождения в двух смежных символах, то кодируют первоначально принятое и скорректированное сообщение и сравнивают его с принятым закодированным сообщением. Если сообщения отличаются во всех последующих сравниваемых символах, то в этом случае произошли ошибки при приеме двух смежных символов первоначально переданного сообщения. Эти символы заменяют на символы декодированного сообщения. Если сравниваемые закодированные сообщения отличаются одним символом, то произошла ошибка при приеме закодированного сообщения. В этом случае осуществляют корректировку искаженного символа закодированного сообщения.The sequence of blocks is served in the first storage device 2, where they form a message in the form of a sequence of characters {7, 0, 1, 0, 3, 0, 5, 1, 7, 2, 1, 6, 2, 2, 6, 7, 3 , 1, 5, 2, 7}. The generated message using devices 4 and 6 is transmitted over the communication line and stored in the device 7 at the receiving end of the communication line. The message generated by device 2 is encoded in device 3, where each message symbol is determined in accordance with the formula β _i ≡ β _i-1 + a _i {mod Р) and the encoded message in the form {7, 7, 0, 0, 3, 3, 0, 1, 0, 2, 3, 1, 3, 5, 3, 2, 5, 6, 3, 5, 4} using devices 4 and 6 are also transmitted over the communication line and stored in the device 7 at the receiving end of communication line. Each symbol of the received encoded message in the device 8 is decoded in accordance with the formula

(mod P), where

. In the resolver 9, the symbols of the decoded message are {7, 0, 1, 0, 3, 0, 5, 1, 7, 2, 1, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7} compared with the characters of the originally received message stored in the second storage device 7. If there are no differences in the characters, then using devices 10 and 5 transmit information to the other end of the communication line to continue transmitting subsequent messages. If there are discrepancies in the compared characters, then the distorted characters are corrected. At the same time, all distorted characters of the originally received message are replaced with the characters of the decoded message, if there are no discrepancies in two adjacent characters. If there are discrepancies in two adjacent characters, then the originally received and corrected message is encoded and compared with the received encoded message. If the messages differ in all subsequent compared characters, then in this case there were errors when receiving two adjacent characters of the originally transmitted message. These characters are replaced with decoded message characters. If the compared encoded messages differ in one character, then an error occurred while receiving the encoded message. In this case, the distorted character of the encoded message is corrected.

If there are discrepancies in three or more adjacent characters, then information is transmitted via the feedback channel to retransmit the generated message. In these cases, an error will be detected but not corrected.

For example, if two adjacent characters of the 10th and 11th are distorted in the original message and instead of the values 2 and 1, the values 3 and 4 are accepted, and the characters of the received encoded message are not distorted, then the encoding of the originally received message {7, 0, 1, 0, 3, 0, 5, 1, 7, 3, 4, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7}, we get the encoded message in the form {7, 7 , 0, 0, 3, 3, 0, 1, 0, 3, 7, 5, 7, 1, 7, 6, 1, 2, 7, 1, 8}, which differs from the received encoded message {7, 7 , 0, 0, 3, 3, 0, 1, 0, 2, 3, 1, 3, 5, 3, 2, 5, 6, 3, 5, 4} by the presence of discrepancies not only in two adjacent shibochnyh symbols, but also in all subsequent characters being compared. Replacing the values 3 and 4 with the values 2 and 1 in the originally received message and encoding it, we obtain a complete match of its characters with the characters of the received encoded message.

If the 10th character is distorted in the received encoded message and the value 6 is taken instead of 2, and the characters of the originally received message are not distorted, then decoding the message {7, 7, 0, 0, 3, 3, 0, 1, 0, 6, 3, 1, 3, 5, 3, 2, 5, 6, 3, 5, 4} we get a sequence of characters in the form {7, 0, 1, 0, 3, 0, 5, 1, 7, 6, 5, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7}, which will be different from the originally received message {7, 0, 1, 0, 3, 0, 5, 1, 7 , 2, 1, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7} with values in two adjacent 10th and 11th characters. In this case, replacing the value 6 with the value 2 in the received encoded message and decoding it, we obtain a complete coincidence of its characters with the characters of the originally received message. If you encode the originally received message {7, 0, 1, 0, 3, 0, 5, 1, 7, 2, 1, 6, 2, 2, 6, 7, 3, 1, 5, 2, 7} , then the received message {7, 7, 0, 0, 3, 3, 0, 1, 0, 2, 3, 1, 3, 5, 3, 2, 5, 6, 3, 5, 4} will differ from received encoded message {7, 7, 0, 0, 3, 3, 0, 1, 0, 6, 3, 1, 3, 5, 3, 2, 5, 6, 3, 5, 4} by a discrepancy in one character . In this case, the symbol of the received encoded message is corrected. Replace value 6 with value 2.

Since distorted characters can be corrected, the average number of transmissions of one message decreases and the information transfer rate increases.

If one bit is added in the characters of transmitted messages to check for parity, then three or more distorted adjacent characters in the originally received message can be corrected. Due to this, the speed of information transfer also increases.

The transmission speed of information can also be increased by simultaneously transmitting the initial and encoded messages on different channels.

The implementation of the proposed method does not cause difficulties, since all the blocks and nodes included in the device that implements the method are well known and widely described in the technical literature.

Sources of information

1. S.I. Bychkov. Space radio engineering complexes. M .: Soviet Radio, 1967.

2. Fink L.M. Theory of discrete message transmission. M .: Soviet Radio, 1963.

3. A method of transmitting discrete information in a radio line with pseudo-random tuning of the operating frequency and a device for its implementation. Application for invention No. 99123808/09 from 10.11.1999 - IPC 7 N 04 B 1/713.

Claims (3)

1. A method for transmitting discrete information in feedback systems, including dividing the input signal into blocks of length n bits at a transmitting end of a communication line, a sequence of blocks of length n bits is stored, a message is generated, and the generated message is transmitted twice along the communication line, and at the receiving end of the line communications remember the received messages, transmit information on the feedback channel to continue transmitting subsequent messages, if the received messages match, and transmit information on the feedback channel for repeated message transmission, if the twice received messages do not match, characterized in that at the transmitting end of the communication line, the retransmitted generated message is encoded, each character of the generated message is determined in accordance with the formula β _i = β _i-1 + α _i (mod P), where P = 2 ⁿ ; the symbols α, β are numbers written in the form of signs of a binary number system and presented in the form of a sequence (combination) of zero and single bits; α _i , β _i - symbol and encoded symbol corresponding to this block of the generated message; β _i-1 - encoded character of the previous block of the generated message; and at the receiving end of the communication line, each symbol of the re-received encoded message is decoded in accordance with the formula

(mod P), Where

, comparing the characters of the originally received message with the characters of the re-received decoded message, while if there are discrepancies in the compared characters and there are no discrepancies in the two adjacent characters of the received messages, then the distorted characters are corrected and the distorted characters of the originally received message are replaced with the characters of the received decoded message, and if there are differences in two adjacent characters of the originally received and decoded messages, then encode the corrected initial A well received message, similarly to the transmitting end of the communication line, is compared with a received encoded message, two distorted adjacent characters of the originally received message are replaced with decoded characters of the compared encoded messages, and information is transmitted via the feedback channel to continue transmitting subsequent messages, and if If there are discrepancies in three or more adjacent characters of the originally received and decoded messages, then they transmit information via the feedback channel to Thorne transmitting the generated message. 2. The method according to claim 1, characterized in that the initially generated and encoded messages are simultaneously transmitted via various communication channels. 3. The method according to claim 1 or 2, characterized in that in the characters of the transmitted messages add one bit to check for parity and correct distorted adjacent characters in the originally received message.

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