The method of discrete information transmission in a radio link with a pseudorandom operating frequency tuning

 

The invention relates to the field of telecommunications and computer technology, in particular to methods and devices for data transmission in the computer network by radio with pseudorandom change the operating frequency. The technical result is to increase the noise immunity and secrecy of communication. The technical result is achieved by the fact that, at the transmitting end of the radio link shall divide the input signal into blocks formed in the form of binary vectors of length n-bits in accordance with the number of frequency channels p=2nform two binary pseudorandom vector sequences by simultaneous parallel recording information from various bits of the shift register, while the length of each binary vector pseudo-random sequence is chosen equal to the length of the binary vector of the block of the input signal, encode a binary vector of the block of the input signal by adding modulo two bits with bits of the first binary vector of pseudorandom sequences have been rebuilding transmitter on a frequency in accordance with the codes, which form in the form of the second binary vector of pseudo-random sequences, modulation hour simultaneously at all frequencies, converting the signal to an intermediate frequency, amplification, demodulation and the formation of a binary vector demodulated signals, the formation similarly as on the transmission side of the two binary vectors of pseudo-random sequences, the implementation of the decoding signal by adding modulo two bits of the first binary vector pseudo-random sequence of bits of the binary vector demodulated signal and the signal being sent to the target device, and the transmitter frequency modulate error-correcting code, and the restructuring of the transmitter is carried out simultaneously at several frequencies, the first frequency is chosen for the frequency channel, the number of which corresponds to the code of the second binary vector of pseudo-random sequences, and all other frequency channels to choose sequential switching in accordance with the value of the symbol "1" in the corresponding digit of the encoded binary vector of the block of the input signal, and on the receiving end of the radio link after demodulation of signals in the frequency channels form a binary vector, the bits which are set to "1" when the presence of a signal in the corresponding frequency channel numbers that follow often is.

The invention relates to the field of radio communications and computing, and more particularly to methods and devices for data transmission in the computer network by radio with pseudorandom change the operating frequency.

Known methods of discrete information transmission in a radio link with pseudorandom change the operating frequency (see, for example, [1] pages 19-35, the application for the invention 99123808/09, 10.11.1999 [2]).

In the known methods the transmission of discrete information performed by the spread spectrum signals by a pseudo-random adjustment of the operating frequency.

The closest to the technical nature of the claimed method is a method described in the application 99123808/09, 10.11.1999. The method includes transmitting end of the radio division of the input signal into blocks formed in the form of binary vectors of length n-bits in accordance with the number of frequency channels p=2nthe formation of two binary vectors of pseudo-random sequences by simultaneous parallel recording information from various bits of the shift register, while the length of each binary vector pseudo-random sequence is chosen equal to the length of the binary vector, the bits about the bits of the first binary vector of pseudo-random sequences, serial reconstruction of the transmitter on a frequency in accordance with the codes that form in the second form binary vectors a pseudo-random sequence, the modulation frequency of the transmitter and the subsequent emission of a signal in space signal at the receiving end of the radio link simultaneously at all frequencies, the selection according to the code of the second binary vector pseudo-random sequence in the frequency channel on which the transfer was made, converting the signal to an intermediate frequency, amplification, demodulation and the formation of a binary vector demodulated signals, the formation similarly as on the transmission side of the two binary vectors of pseudo-random sequences, the decoded signal by adding modulo two bits of the binary vector signal occurring in the frequency channel bits of the first binary vector pseudo-random sequence and the signal is applied to the target device.

However, the way the prototype has a drawback. Despite the fact that the carrier frequency of the transmitter is reconstructed in accordance with the pseudo-random code sequence, the communication system is not failsafe active intrusion. Po, allowing it to optimally distribute the limited capacity of interference around the radio.

The invention is directed to improving the noise immunity (stealth and noise immunity) connection.

This is achieved by the known method of discrete information transmission in a radio link with pseudorandom change the operating frequency, which consists in dividing the input signal into blocks formed in the form of binary vectors of length n-bits in accordance with the number of frequency channels p=2n, the formation of two binary vectors of pseudo-random sequences by simultaneous parallel recording information from various bits of the shift register, while the length of each binary vector pseudo-random sequence is chosen equal to the length of the binary vector of the block of the input signal, the encoding of the binary vector of the block of the input signal by adding modulo two bits with bits of the first binary vector of pseudo-random sequences, the restructuring of the transmitter on a frequency in accordance with the codes that form in the second form binary vectors a pseudo-random sequence, the modulation frequency of the transmitter and after is the frequency, converting the signal to an intermediate frequency, amplification, demodulation and the formation of the binary vector demodulated signals, the formation similarly as on the transmission side of the two binary vectors a pseudo-random sequence, the decoded signal by adding modulo two the first binary vector pseudo-random sequence of bits of the binary vector demodulated signal and the signal at the target device, according to the invention are modulated transmitter frequency error correcting code, and the restructuring of the transmitter is carried out simultaneously at several frequencies, the first frequency is chosen for the frequency channel, the number of which corresponds to the code of the second binary vector of pseudo-random sequences, and all other frequency channels to choose sequential switching in accordance with a value of "1" in the corresponding digit of the encoded binary vector of the block of the input signal, and at the receiving side after demodulation of signals in the frequency channels form a binary vector, the bits which are set to a value "1" when the presence of a signal in the corresponding frequency channel numbers that follow the frequency channel of the spine characteristics of the claimed method under a binary vector refers to the signal as a sequence of zero and unit bits corresponding to the representation of a number (symbol) in binary.

Listed set of essential features provides high noise immunity because the transmitter emits simultaneously at different frequencies, including the difference between which can have different values at each jump of frequency. Such formation of the signal with pseudo-random rearrangement of the operating frequency and energy suppression with active intrusion makes it difficult to explore, as emitted by the transmitter signal is expanded by direct modulation of the carrier frequencies of error-correcting code with a large base, and then due to the abrupt change in operating frequency of the transmitter. This is the distribution of the signal energy in a large bandwidth than is provided by the energetic, structural and information secrecy signals. In such circumstances, the jammer must either allocate the limited capacity of interference over the entire space of the signal, thereby creating a low power spectral density of interference, or to use the whole available power of the transmitter noise in the small space, leaving the remaining space is sluchainoi operating frequency tuning in the conditions of active intrusion.

The possibility of technical realization of the inventive method is explained as follows.

If the number of frequency channels is 2kthen the length of the binary vector of the block of the input signal is chosen equal to k bits. For example, for 16 frequency channels length binary vector of the block of the input signal should be 4 bits.

The formation of pseudo-random sequences of maximum length, containing 2n-1 character, can be done by using a linear shift register having n bits, the feedback of which is determined by referring to the selected primitive polynomial of degree n. Finding primitive polynomials of degree n is given in [3] on pages 74-75.

The formation of each binary vector pseudo-random sequence of length k bits can be done by removing information from k different bits of the shift register numbers that can be defined by the value of the entered security key (seed bits of the shift register). For example, by defining the parent element

l0K(mod q), if l0<2, l0=2,

and the numbers of discharge of the shift register according to the formula

l1=lthe villages and to the shift register, having 256 bits q=257, and shift register having 128 bits q=127. In this case, due to the exponentiation of the parent number of l0we will move from one element of the field Fq to another. In this case, as shown in [3] pages 44, if l0- an element of order m, then all elements of l0l20l30,...,lm-10will be different.

In accordance with the second binary vector pseudo-random sequence (e.g. 1000) ID1for adjustment of the transmitter at a first carrier frequency will correspond to the 8-frequency channel, as in binary 1000 corresponds to the number 8.

The encoding block of the input signal can be realized by adding modulo two characters of the first binary vector pseudo-random sequence (e.g., 0011), with symbols of the binary vector of the block of the input signal (e.g., 0111)

To2=0100.

In accordance with the generated codes K1and K2the transmitter will emit a signal bearing simultaneously on 8 - and 11-frequency channels, since 9-th channel will correspond to a zero discharge code2the 10th digit will correspond to the first digit of the code To2, 11-th channel will sootvetstvenno side compute the characters of the binary vectors of pseudo-random sequences, one of which is used to determine the channel number in which you may receive the encoded signal. For our example, in accordance with the pseudorandom code sequence (10008) the appearance of the signals should be expected in 9, 10, 11, 12-m channels. The signal appeared in the 11th channel, form a binary vector2=0100. Decoding the generated signal is carried out by adding modulo two bits of code To the2(0100) bits of the first binary vector pseudo-random sequence (0011). The resulting number (01117) serves on the target device.

The proposed method can be implemented using the devices represented by the flowchart in Fig.1, where:

unit 1 - the signal source;

unit 2 - the first shift register;

unit 3 - the encoder;

unit 4 - the frequency synthesizer;

block 5 - modulator;

unit 6 - transmitter;

unit 7 - the receiver;

unit 8 - second shift register;

unit 9 - decoders;

the block 10 to the target device,

and by the flowchart of Fig.2, where the blocks 11 to 16 - bits 1-6 of the shift register and the block 17 is modulo two.

For ease of description of the operation of the device will use mH frequency channels 16, then to transfer one block of the input signal can be used a binary vector of length 4 bits.

To define the structure of the shift register is chosen primitive polynomial of the sixth degree, such as

6+5+1.

For the selected primitive polynomial, the structural diagram of the shift register with feedback will be of the form shown in Fig.2. Generated by the random number generator security key length of 6 bits

<6,5,4,3,2,1>

where1=0,2=0,3=0,4=1,5=1,6=1 is supplied to the shift register and is used for initial filling of bits of the shift register. Binary characters 5 and 6 of the discharge of the shift register receives at each stage to the input of the adder 17 modulo two, and from the output of the modulo two symbol=the engines (block 11). The status bits for each measure in the process of the shift register is determined by the expression

i=i-1for,1=.

If characters will be removed from the sixth discharge6then the binary pseudo-random sequence, the maximum period will be of the form

{1110000010000110001010011110100011100100101101110110

011010101111}.

Note that the period of this sequence is any non-zero set of six digits 0 and 1 occurs only once.

If the binary number will be removed from 1, 2, 3 and 4-th digit of the shift register (blocks 11, 12, 13, 14) on each step of his work and with a set of <1,2,3,4> will associate a binary vector (number) x=1+22+223,+234the sequence of binary numbers in the process of the register can be viewed as a sequence of characters x(0, 1, 2,...,15 5, 10, 5, 11, 7, 15, 15, 15, 14, 12,...}.

If the binary number will be removed simultaneously with 1, 2, 5, 6-th bits of the shift register (blocks 11, 12, 15, 16) on each step of his work with a set of <6,5,2,1> will match the number in the form y=6+25+222+231the sequence of binary numbers in the process of the shift register can be viewed as a sequence of symbols y{0,1,2,...,15}

y={3, 3, 1, 8, 4, 0, 0, 2, 9, 12, 4, 0, 2, 11, 5, 8, 4, 2, 9, 14, 13, 12, 6, 11, 7, 3, 1, 10, 13, 12, 4, 2, 11, 7, 1, 8, 6, 9, 12, 6, 9, 14, 15, 5, 10, 15, 7, 1, 10, 15, 5, 8, 6, 11, 5, 10, 13, 14, 13, 14, 15, 7, 3,...}.

Analysis of the generated sequences x and y shows that in the interval corresponding to the period of 63 cycles of operation of the shift register, each of the symbols {1, 2,...15} occurs exactly four times. The symbol for zero, both sequences occurs exactly three times, and the sequence x and y can not be obtained from one another in a cyclical shift. In the sequences x and y no latent period is Uchenye symbol sequences x and y as binary vectors received in the encoder 3, where form codes K1and K2for adjustment of the transmitter to the corresponding carrier frequencies.

Similarly, on the receiving side form the symbols x, y in the unit 8 for determining the numbers of frequency channels, in which it is reasonable to expect signals and performing the decoding of received signals.

Thus due to the modulation of the carrier frequencies of the transmitter error-correcting code (e.g., Barker) with large base provides the energy reserve of the radiated signals, and the radiation signal simultaneously on two or more frequencies provides increased structural secrecy of the radiated signals and noise immunity due.

Because when the shift register has the opportunity to skip the bars of his work, for which the symbols are generated binary vectors of pseudo-random sequences are the same in all or several selected discharges, provided the statistical uniformity of the used frequency channels during transmission of the permanent characters of the source text and excludes the application of statistical methods in cryptanalysis to break the pseudorandom sequence.

If the frequency channel corresponding to the second code binary is Loka input even parity, there is a chance of detecting and correcting errors in the decoded message, which increases the noise immunity of communication.

If the code to rebuild the transmitter on the first carrier frequency will be formed by adding modulo two bits of the second binary vector pseudo-random sequence of bits encoded binary vector of the block of the input signal, at the receiving side has the ability to filter false signals due to the formation of additional binary vector by adding modulo two bits of the second binary vector pseudo-random sequence of bits of the binary vector corresponding to the ordinal number of frequency channel for the first frequency of the transmitter and comparing the received additional binary vector with a binary vector of demodulated signals.

If the frequency channel corresponding to the second code of binary vector pseudo-random sequence is not used, in this case, increasing structural secrecy of the emitted signals and difficult dissection codes, pseudo-random sequences.

Implementation of the proposed method is straightforward, since all blocks and components, the Nike information

1. C. I. Borisov, V. M. Zinchuk, A. E. Lirnarev, N. P. Mukhin, V. I. Shestopalov. The immunity of radio communication systems with expansion of the range of signals, the method of pseudo-random adjustment of the operating frequency. M.: Radio and communication, 2000.

2. The method of discrete information transmission in a radio link with pseudorandom change the operating frequency and the device for its implementation. The application for the invention 99123808/09, 10.11.1999, IPC 7 H 04 1/713.

3. B. N. Voronkov, V. I., Tupot. Methodological guide for the development of the protection of information in computer networks. Voronezh: Voronezh state University, 2000.

Claims

1. The method of discrete information transmission in a radio link with pseudorandom change the operating frequency, comprising at the transmitting end of dividing the input signal into blocks formed in the form of binary vectors of length n bits in accordance with the number of frequency channels p=2n, the formation of two binary vectors of pseudo-random sequences by simultaneous parallel recording information from various bits of the shift register, while the length of each binary vector pseudo-random sequence is chosen equal to the length of the binary Liu two bits with bits of the first binary vector of pseudo-random sequences, the restructuring of the transmitter on a frequency in accordance with the codes, which form in the form of the second binary vector pseudo-random sequence, the modulation frequency of the transmitter and the subsequent emission of a signal in space signal at the receiving end of the radio link simultaneously at all frequencies, converting the signal to an intermediate frequency, amplification, demodulation and the formation of a binary vector demodulated signals, the formation similarly as on the transmission side of the two binary vectors of pseudo-random sequences, the implementation of the decoding signal by adding modulo two bits of the first binary vector pseudo-random sequence of bits of the binary vector demodulated signal and the signal being sent to the target device, characterized in that what frequency transmitter modulate error-correcting code, and the restructuring of the transmitter is carried out simultaneously at several frequencies, the first frequency is chosen for the frequency channel, the number of which corresponds to the code of the second binary vector pseudo-random sequence, and all other frequency channels to choose sequential switching in accordance with the value of the symbol "1"is the line after demodulation of signals in the frequency channels form a binary vector, discharges which take the value "1" when the presence of a signal in the corresponding frequency channel numbers that follow a frequency channel that is determined by the code of the second binary vector pseudo-random sequence.

2. The method according to p. 1, characterized in that the frequency channel corresponding to the second code of binary vector pseudo-random sequence on the transmitting side, apply only to ensure an even number of simultaneously used carrier frequencies, and at the receiving side is used to check the encoded binary vector of the block of the input signal on parity.

3. The method according to p. 1, characterized in that the frequency channel corresponding to the second code of binary vector of pseudorandom sequences are not used for transmission and reception of messages.

4. The method according to any of paragraphs.1-3, characterized in that the miss those cycles of operation of the shift register, for which the generated binary vector of pseudorandom sequences coincide.

 

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