RU2765482C1 - Method for blocking cellular communication with self-excitation protection - Google Patents

Abstract

FIELD: radio engineering and communication.

SUBSTANCE: invention relates to radio engineering and can be used to block relay-type cellular communication with protection against self-excitation. In the method of blocking cellular communication, the received and amplified broadband signal is phase-keyed according to the law of a low-frequency pseudorandom sequence in real time. Phase-keyed signal is stored in the delay line for subsequent re-emission. Delayed signal is re-emitted n times in re-emission period with duration nT, wherein n is a random integer taking an equiprobable value from the minimum to the maximum allowable value and selected before the beginning of each re-emission period, with such a choice of the number n, the interfering signal does not have the nature of periodic pulse interference. Signal reception during re-emission is not performed and signal reception is resumed upon expiration of protective time interval after completion of re-emission period, thus preventing generation of signal in absence of device to be blocked.

EFFECT: technical result consists in ensuring the impossibility of restoring the blocked signal due to the complication of the structure of the interference electromagnetic field.

3 cl, 1 dwg

Description

The invention relates to the field of radio engineering, which deals with the creation of artificial interference to radio communications, in particular to methods for blocking cellular communication of a relay type with protection against self-excitation. The invention can be used to block the passage of information flows in radio communication networks and data transmission.

A known method of counteracting radio communication is described in US patent No. 4103237. This method consists in the fact that the signals of broadband transmitters are received at the antenna, introduce errors, then store the prepared (with introduced errors) implementation of the received signal with a duration T (determined by the capacity of the buffer memory used for storing sample of blocked signals), after which they are repeatedly re-emitted, and the multiplicity of re-emission is selected for reasons of damage by interference to a sufficient part of the signals of blocked devices. The transmitter is always blocked for the time the signals are entered into the buffer memory (for time T), the receiver, respectively, is open, then the receiver is closed and an interference signal is emitted with a duration of nT, where n is the initially selected re-emission multiplicity. After radiation, the signal is again entered into the buffer memory. Thus, an interfering signal with duration nT repeats periodically with a period of (n+1)T, that is, the interference is strictly regular (periodic) in nature. Hardware and software methods of combating precisely this kind of interference are the most developed at the present time and are successfully used in cellular communication equipment. Therefore, the disadvantage of this method is the low efficiency of interference.

The closest in essence to the claimed is a method of local suppression of mobile communications according to Eurasian patent No. 006784. The prototype method includes: amplification of the received broadband signal and its re-emission with phase manipulation according to the law of a low-frequency pseudo-random sequence, while the phase is manipulated with the received and amplified signal in real time, and the spectrum of the re-emitted signal is kept within the allowed frequency band . This method has a significant drawback: if the transmitting and receiving antennas are in close proximity to each other, more precisely, if the end-to-end gain of the receive-transmit path is greater than the pass-through attenuation between the receiving and transmitting antennas, then the system becomes unstable, i.e. self-excitation. Naturally, in this case, communication blocking does not occur.

The task is to create such a method of blocking cellular communications in a local area on the principle of setting relay interference so that devices designed to implement this method:

- were free from self-excitation, regardless of the relative position of the receiving and transmitting antennas ("direct" self-excitation);

- did not switch to the auto-generation mode in the presence of obstacles reflecting electromagnetic waves on the path of the interference signal propagation (self-excitation through an "intermediary"), regardless of the location of these obstacles;

- were comparable in terms of blocking reliability and blocking radius with devices operating on the relay principle, in which protection against self-excitation of any type (“direct” or through an “intermediary”) is not provided, but which are in operation (that is, the mutual position of the antennas and the position of the reflecting obstacles is such that there is no self-excitation in the device).

The problem is solved by the fact that the method of blocking cellular communication includes receiving a broadband signal during the time T, amplifying the received signal and re-radiating it with phase manipulation according to the law of a low-frequency pseudo-random sequence, while phase manipulation is performed with the received and amplified signal in real time, and the spectrum of the re-emitted signal is kept within the allowed frequency band, while the method differs in that the signal received and processed in the above way is stored in the delay line for subsequent re-emission, the signal is not received during re-emission, the delayed signal is re-emitted n times in the re-emission period of duration nT , while n is a random integer that takes an equiprobable value between the minimum and maximum allowable and is selected before the start of each re-emission period, and then the signal reception is resumed after the guard time interval after the end of ne reemission period.

The received wideband signal may be from multiple base stations or user terminals.

The method is implemented by means of a device containing a receiving antenna, an input controlled analog switch, an input bandpass filter, a normalizing high-frequency amplifier, a controlled phase switch, a control pseudo-random sequence generator, an output power amplifier, a reradiating antenna, a delay line, a control signal generator with a built-in random number sensor, an output controlled analog switch and a controlled analog switch in the feedback of the delay line, while the output of the receiving antenna is connected through the input controlled analog switch to the input of the input band-pass filter, the output of which is connected to the input of a normalizing high-frequency amplifier, the output of which is connected to the high-frequency input of the controlled phase switch, the control input of the controlled phase switch is connected to the generator of the control pseudo-random sequence, the output of the controlled phase switch through the delay line and through the output controlled analogue The new switch is connected to an output power amplifier, the output of which is connected to a reradiating antenna, the controlled analog switches are connected to and controlled by a control signal generator with a built-in random number sensor, while the function of choosing the number n is implemented by means of a controlled analog switch in the feedback of the delay line and the generator control signals with a built-in random number generator.

The technical result consists in ensuring the impossibility of restoring the blocked signal by complicating the structure of the interference electromagnetic field. At the same time, the implementation of the method is provided for any mutual arrangement of the transmitting and receiving antennas, regardless of the characteristics of the surrounding area.

In FIG. 1 shows a diagram of a device for implementing the proposed method.

The device for implementing the method contains a receiving antenna 1, an input analog switch k1, an input band-pass filter 2, a normalizing high-frequency amplifier 3, a controlled phase switch 4, a control pseudo-random sequence generator 5, an output power amplifier 7, a reradiating antenna 8, a delay line 6, a generator 9 control signals with a built-in random number generator, the output analog key k2 and the key k3 in the feedback of the delay line.

The output of the receiving antenna 1 through the input analog key k1 is connected to the input of the input band-pass filter 2, the output of which is connected to the input of the normalizing high-frequency amplifier 3, the output of which is connected to the high-frequency input of the controlled phase switch 4. The control input of the controlled phase switch 4 is connected to the generator 5 of the control pseudo-random sequence, the output of the controlled phase switch 4 through the delay line 6, in the feedback of which the analog key k3 is installed, and through the output analog key k2 is connected to the output power amplifier 7, the output of which is connected to the reradiating antenna 8. The analog switches k1, k2 and k3 are connected with a generator of 9 control signals with a built-in random number generator and are controlled by it.

The difference from the device that implements the prototype method is that there is a control signal generator 9 with a built-in random number sensor, analog keys k1, k2, k3 and a delay line 6.

Using this device, the inventive method is carried out as follows.

The device cycles through the first, second and third states.

The first state lasts a period of time T, the duration of which is determined by the delay time of the delay line 6, which is determined by the amount of buffer memory. In this case, the delay line is just a buffer memory, and the time T is the characteristic of the line, that is, the delay time.

In the first state, the key k1 is closed, the keys k2 and k3 are open. The antenna 1 is used to receive a broadband signal. The received wideband signal may be a sum signal from multiple base stations or user terminals.

The received signal is filtered by the input bandpass filter 2, amplified, normalized by a high-frequency amplifier 3 and modulated in phase by a controlled phase switch 4, that is, phase manipulation is performed according to the low-frequency pseudo-random sequence law based on data from the pseudo-random sequence generator 5. The spectrum of the re-emitted signal is kept within the allowed frequency band.

The signal from the output of the phase switch 4 is stored in the delay line 6, where it is accumulated for subsequent recycling through the feedback key k3, amplification by the power amplifier 7 and radiation by the reradiating antenna 8.

In the second state, the switch k1 is open, and the switches k2 and k3 are closed. Amplification of the delayed signal by the power amplifier 7 and a new recording of the own signal into the delay line 6 occur. sampling a random number from the initially given allowed interval. The signal accumulated in the delay line is repeatedly (n times) after amplification by the power amplifier 7 is emitted by the reradiating antenna 8. numbers built into the generator 9 control signals.

The number n is chosen randomly so that the interference signal does not have the nature of a periodic impulse noise, and for non-periodic impulse noise, countermeasure algorithms are developed much worse than for periodic ones.

In the third state, the generator 9 control signals with a built-in random number sensor holds the keys K1, K2 and K3 in the open state. The duration of this state is equal to the guard time interval and is chosen from considerations of relaxation of possible reflected signals. The guard interval is necessary to protect against self-excitation through the "intermediary", that is, due to a signal from reflective obstacles in the path of the blocking signal.

To organize a protective time interval, the control signal generator with a built-in random number generator again allows the reception of signals with a delay for the time interval necessary for the relaxation of the re-reflected signals. Thus, the reception of the signal is resumed after the expiration of the guard time interval, which begins at the end of the re-emission period.

Self-excitation of the system, which is not related to the relative position of the antennas, occurs for the following reason. The signal after radiation begins to propagate in space. In the course of propagation, there may be a reflective obstacle. The signal is reflected from the obstacle and returns back to the location of the blocker's receiving antenna. Naturally, this signal is delayed relative to the emitted signal for a time determined by the speed of light and the distance to the reflecting obstacle, and the level of this signal is related to the reflection coefficient and the distance to the obstacle. If the delayed signal reflected from the obstacle exceeds the level of the signal from the subscriber terminals (base stations) and falls within the signal reception time window for blocking, then in the delay line 6 (or some other type of memory), instead of the useful signal, the reradiated signal reflected from the obstacle is stored signal. The re-emission of such a signal does not perform the function of blocking (the correlation between the interfering and blocked signals is lost). In addition, if the blocking object has stopped trying to establish communication, cyclic generation continues, since the delayed signal reflected from the obstacle continues to arrive at the receiving antenna, and the system confuses this signal with the useful one that needs to be blocked, and again generates a signal that, in the absence of a device, which needs to be blocked is auto-generation (self-excitation).

After the guard time expires, the device returns to the first state, and the described sequence of states is repeated.

Thus, when the signal is received and accumulated in the delay line 6, re-emission does not occur, but when re-emission occurs, there is no reception.

In addition, in order to more reliably maintain operability, that is, to combat the negative effect of autogeneration associated with the possible presence of reflective obstacles in the path of the blocking signal, it is proposed to introduce an additional guard interval (after the emission of an interference signal, the system does not immediately switch to the receive mode, that is set the signal into memory, and after the expiration of the guard interval, the duration of which is selected from considerations of the relaxation of possible reflected signals).

The result of the introduction of a guard interval between re-emission and reception is the impossibility of losing the efficiency of the method for any location of reflecting objects relative to the receiving and transmitting antennas.

The claimed method was tested in a manner similar to the patent prototype testing.

First, the circuit was assembled, presented in the Eurasian patent No. 006784, describing the prototype. The filter was tuned to the frequency band 2110-2170 MHz, that is, the test was carried out in the UMTS band (downlink). The frequency of the pseudo-random sequence generator was set to 5 kHz. The power supplied to the reradiating antenna was 30 dBm (1 W) and the input sensitivity was minus 60 dBm. Whip band (2110-2170 MHz) receiving and re-radiating antennas with a circular pattern were used. The re-radiating antenna was installed in the center of a flat flat area (field) in an open space, and the receiving antenna at a distance of 50 m from the transmitting one (the edge of the selected area measuring 50x50 m). As a test device, a Huawei SmartZ smartphone was selected, forcibly set to “3G only” mode. Multiple attempts were made to establish a connection both on the activity of the test device and on the initiative of an external subscriber. No differences were observed in the results.

The following results of the experiment were obtained: a zone of sure blocking - within a radius of 11 m from the installed reradiating antenna; zone of unstable communication - radius from 11 to 15 m; stable communication zone - further 15 m from the position of the reradiating antenna.

When the receiving antenna approached the location of the reradiating one at a distance of less than 25 m, the blocker switched to self-excitation mode and stopped blocking.

Then the device was assembled according to the claimed method. The parameters of amplifiers, filters, antennas, as well as the initial location of the receiving and re-radiating antennas were set the same as in the first experiment. Two options for setting up the assembled device were considered.

In the first variant, the value of the number n was chosen to be deterministic and equal to 4 (4 re-emission cycles per one dialing cycle, that is, 80% of the signal is damaged by regular impulse noise). The guard interval has been set to zero. Such a scheme was assembled to analyze the operability of the method according to US patent No. 4103237, and the signal damage by interference by 80% was applied based on the recommendations described in this patent.

The following results were obtained: a zone of sure blocking - within a radius of 8 m from the installed reradiating antenna; unstable communication - from 8 to 11 m; stable connection - further 11 m.

When the antennas approached, the characteristics of the blocking zone did not change up to a 1.5-meter distance between them (at this distance, electromagnetic coupling arose due to insufficient shielding of the device).

With a compact location of the antennas relative to each other (at a distance of two to three meters) and the transfer of the entire structure to the site, from which a high all-metal fence is located at a distance of 30 m, the result of self-excitation through an “intermediary” was obtained, that is, the device lost stability and, respectively, performance.

In the second variant, n was chosen randomly and equally likely from the alphabet 2; 3; 4; 5; 6. The guard interval was chosen to be one twentieth of the signal delay time in the delay line. The average damage of the signal by interference in this case was 80%, but the interference from a regular pulse turned into a pulse with a random pulse duration.

The following results were obtained: a zone of sure blocking - within a radius of 10 m from the installed reradiating antenna; unstable communication - from 10 to 14 m; stable connection - more than 14 m.

As the antennas approached, the characteristics of the blocking zone did not change, as in the case of a fixed number n.

With a compact location of the antennas relative to each other (at a distance of two to three meters) and the transfer of the entire structure to the site, from which a high all-metal fence is located at a distance of 30 m, the result of self-excitation through an "intermediary" was not obtained, nor was it obtained and at a variety of other device locations relative to the reflective obstacle.

Thus, the method of blocking cellular communications with protection against self-excitation in terms of the range of confident blocking (that is, in terms of efficiency) is only slightly inferior to the prototype method (by 9%), and significantly outperforms US No. 4103237 (by 25%). The device does not switch to the self-excitation mode both when the receiving and re-emitting antennas approach, and in the presence of obstacles reflecting electromagnetic waves, that is, it can be used in any territory.

Claims (3)

1. A method for blocking cellular communications, including receiving a broadband signal during time T, signal processing, including amplifying the received signal and phase manipulation according to the low-frequency pseudo-random sequence law, performed with the received and amplified signal in real time while maintaining the spectrum of the re-emitted signal within allowed frequency bands, and re-emission of the processed signal, characterized in that the signal processed in the above way is stored in the delay line for subsequent re-emission, during re-emission, the signal is not received, the delayed signal is re-emitted n times in the re-emission period of duration nT, while n is a random integer a number that takes an equiprobable value from the minimum to the maximum allowable and is selected before the start of each re-emission period, then the signal reception is resumed after the guard time interval after the end of the re-emission period. 2. The method of claim. 1, wherein the received broadband signal is a signal from multiple base stations or user terminals. 3. A device for blocking cellular communications for implementing the method according to any one of paragraphs. 1 or 2, containing a receiving antenna, an input controlled analog switch, an input bandpass filter, a normalizing high-frequency amplifier, a controlled phase switch, a control pseudo-random sequence generator, an output power amplifier, a transmitting antenna, a delay line, a control signal generator with a built-in random number generator, an output a controlled analog switch and a controlled analog switch in the feedback of the delay line, while the output of the receiving antenna is connected through the input controlled analog switch to the input of the input band-pass filter, the output of which is connected to the input of a normalizing high-frequency amplifier, the outputs of which are connected to the high-frequency inputs of the controlled phase switch, the control the input of the controlled phase switch is connected to the generator of the control pseudo-random sequence, the output of the controlled phase switch through the delay line and through the output controlled analog switch is connected to the output amplifier the output of which is connected to the transmitting antenna, the controlled analog switches are connected to the control signal generator with a built-in random number generator and are controlled by it, while the number n selection function is implemented by means of a controlled analog switch in the feedback of the delay line and controlled by a signal from the corresponding output of the generator control signals with a built-in random number generator.

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