KR100544227B1 - Interference signal cancellation system and relay system therefor - Google Patents

Abstract

The present invention discloses a transmission feedback signal removal device for removing a transmission feedback signal in which a part of a transmission signal of a transmission antenna flows into a reception antenna in a repeater of a wireless communication system. The apparatus for removing a feedback feedback signal according to the present invention removes a transmission feedback signal included in the reception signal by changing the transmission feedback signal input to the auxiliary antenna through a phase converter and a variable attenuator and coupling the signal with the reception signal of the reception antenna. Therefore, since the transmission feedback signal removing apparatus according to the present invention can prevent the oscillation of the same frequency repeater by removing the transmission feedback signal, it has a wide frequency characteristic, thereby increasing the capacity of the entire system.

Repeater, Transmission Feedback Signal, Coupling

Description

Transmission feedback signal removing device and relay system using the same {INTERFERENCE SIGNAL CANCELLATION SYSTEM AND RELAY SYSTEM THEREFOR}

1 is a view showing a conventional relay system.

2 is a diagram illustrating a relay system including a device for removing a conventional transmission feedback signal.

3 is a diagram illustrating a relay system including an apparatus for removing a transmission feedback signal according to an exemplary embodiment of the present invention.

4 illustrates an embodiment in which a correlator is implemented as a digital device in a relay system according to an embodiment of the present invention.

5 is a diagram illustrating a relay system including an apparatus for removing an applied transmission feedback signal from two paths according to another embodiment of the present invention.

*** Description of the symbols for the main parts of the drawings ***

100: transmit antenna 200: receive antenna

301: ID signal generator 304: first delay line

306: First correlator 307: First phase shifter

308: first variable attenuator 309: second delay line

310: third delay line 400: repeater

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a transmission feedback signal removing device and a relay system including the same in a wireless communication system for removing a part of a signal transmitted from a transmitting antenna of a repeater to a receiving antenna. .

In order to increase the reach of radio waves in a wireless communication system, the output power of a transmitter may be increased, but the transmission power cannot be increased indefinitely. Therefore, a receiver located far from the transmitter may receive a weak signal or cannot receive a transmission signal due to a path loss. In addition, even though the receiver is a short distance from the transmitter, a radio shadow area that is impossible to receive due to the terrain and features of the region where the receiver is located occurs. A repeater is used to remove the radio shadow area. The repeater receives a weak signal transmitted through a transmission path through a reception antenna, and then amplifies the signal of the same frequency and transmits the signal through a transmission antenna.

1 shows a conventional relay system.

In this relay system, however, as shown in FIG. 1, a transmission feedback signal is generated in which part of a signal transmitted through the transmission antenna 1 is re-received as an interference signal through the reception antenna 2, and such a transmission feedback signal is generated. Since the same frequency as the signal received from the other repeater 3 or the base station causes the amplifier to self-oscillate in the process of amplifying and retransmitting the received signal. Since the oscillation of the repeater may operate as a noise source throughout the repeater installation area, it may cause system paralysis. Therefore, when the repeater is used, the repeater oscillation should be prevented.

In order to prevent the repeater oscillation, conventionally, a frequency conversion repeater is used, and the transmission / reception frequency of the frequency conversion repeater has a specific frequency separation, and the frequency separation is performed using a bandpass filter located at the front end of the transmission / reception. It is possible to obtain sufficient isolation between the receiving antennas. However, when using a frequency conversion repeater, there is a disadvantage that can not efficiently use the frequency resources allocated for the service.

On the other hand, the same frequency repeater has an advantage in terms of efficiency of frequency, but because the transmission and reception frequencies are the same, a separate means for obtaining sufficient isolation between the transmission and reception antennas is required.

2 shows a relay system including a device for canceling a conventional transmit feedback signal.

In the relay system including the conventional transmission feedback signal removing device, as shown in FIG. 2, a transmission signal input from an external transmission system is distributed to transmit a transmission signal of one side to an external transmission antenna 10. In the power distribution unit 20 and the transmission feedback signal removing unit 30 and the transmission antenna 10 which receive another transmission signal among the transmission signals distributed by the power distribution unit, delay the signal for a predetermined time, attenuate the magnitude, and shift the phase. Power synthesizing means 40 for combining the transmission signal inputted through the external reception antenna 50 and the transmission signal input from the interference canceling means 30 to remove the transmission signal input through the reception antenna 50. It consists of.

However, since the distance between the two antennas is changed according to the installation position of the transmission antenna and the reception antenna, the transmission feedback signal removal device has a disadvantage in that the time delay is adjusted accordingly. However, in order to change the time delay of the RF frequency, it is necessary to adjust the length of the coaxial cable. Therefore, each time a repeater is installed, a time delay is measured and a delay line has to be processed accordingly. In addition, when signal attenuation occurs due to changes in the surrounding environment, it cannot be actively compensated for.

Therefore, the present invention is to solve such a problem, in consideration of the effect of the delay line to remove the transmission feedback signal of a wide frequency range, and the transmission feedback signal removal device that can actively cope with changes in the surrounding environment of the repeater and including the same It is an object to provide a relay system.

In order to achieve the above technical problem, a transmission feedback signal removing device according to a feature of the present invention is connected to a repeater for relaying signals where radio waves are not reached in a wireless communication system, so that a part of the signal radiated from the transmission antenna of the repeater A transmission feedback signal removal device for removing a transmission feedback signal flowing into a reception antenna, the apparatus comprising: an ID signal generator for generating an ID signal which is a reference signal for removing the transmission feedback signal, and distributing power of an output signal of the ID signal generator A first coupler for detecting an ID signal from an output signal of the repeater, a first coupler for coupling an output signal of the second coupler and an output signal of the first power divider, and a second coupler The magnitude of the ID signal is analyzed by analyzing a correlation between an output signal and an output signal of the first power divider. A first correlator for outputting a control signal to be small, an auxiliary antenna for receiving a transmission feedback signal flowing from the transmitting antenna into the receiving antenna at a position similar to the receiving antenna, and an output of the first correlator A first phase shifter that receives a signal as a control signal and adjusts a phase of a transmission feedback signal introduced through the auxiliary antenna; a magnitude of an output signal of the first phase shifter by receiving an output signal of the first correlator as a control signal A first variable attenuator for controlling a third delay line connected to the reception antenna to adjust a delay time of a signal received from the reception antenna, a received signal connected to the third delay line and passing through the third delay line And a signal output through the first variable attenuator to couple the received signal to the receiving antenna. A third coupler for applying a signal from which a new feedback signal has been removed as an input signal of the repeater, and is inserted between the third coupler and the first variable attenuator, and from the transmitting antenna to the auxiliary antenna, the first phase shifter and the first The delay time from passing the variable attenuator to outputting the signal from the third coupler is equal to the delay time from the transmitting antenna to the reception antenna and the third delay line to outputting the signal from the third coupler. And a second delay line.

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According to an aspect of the present invention, a relay system includes a repeater for amplifying a signal received by a reception antenna and transmitting it to the outside through a transmission antenna and a transmission feedback signal in which a part of a signal radiated from the transmission antenna of the repeater flows into the reception antenna. A transmission feedback signal removing device for removing
The transmission feedback signal removal device,
ID signal generator for generating an ID signal which is a reference signal for removing the transmission feedback signal, a first power divider for distributing the power of the output signal of the ID signal generator, and a second signal for detecting the ID signal from the output signal of the repeater. A coupler, a first coupler coupling the output signal of the second coupler and the output signal of the first power divider, and analyzing the correlation between the output signal of the second coupler and the output signal of the first power divider to determine the ID. A first correlator for outputting a control signal for minimizing the size of the signal; an auxiliary antenna for receiving a transmission feedback signal in which a signal radiated from the transmitting antenna is introduced into the receiving antenna at a position similar to the receiving antenna; 1, the output signal of the correlator is input as a control signal to adjust the phase of the transmission feedback signal introduced through the auxiliary antenna; A first variable attenuator configured to receive an output signal of the first correlator as a control signal and to adjust a magnitude of an output signal of the first phase converter; a delay of a signal received from the reception antenna connected to the reception antenna; A third delay line for adjusting the time, the reception signal connected to the third delay line passed through the third delay line and the signal output through the first variable attenuator, the received input to the receiving antenna A third coupler for applying the signal from which the transmission feedback signal has been removed from the signal as an input signal of the repeater, and inserted between the third coupler and the first variable attenuator, and the auxiliary antenna and the first phase shifter from the transmission antenna And a delay time from when the signal is output from the third coupler through the first variable attenuator and the number from the transmission antenna. Through the antenna, and a third delay line a second delay line of the same said first delay time until the third signal is output from the coupler.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings the most preferred embodiment that can be easily carried out by those of ordinary skill in the art as follows.

3 is a diagram illustrating a relay system including an apparatus for removing a transmission feedback signal according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the apparatus for removing a feedback feedback signal of the present invention generates an ID signal that generates an ID signal, which is a reference signal for detecting the magnitude and phase of a signal fed back from the transmitting antenna 100 to the receiving antenna 200. Generator 301, a first power divider 302 for distributing the output of the ID signal generator 301, a first coupler 303 for coupling the output signal of the repeater with the output signal of the first power divider 302 ), A second coupler 305 for detecting an ID signal from the output signal of the repeater 400 and transmitting the signal to the first correlator, an output signal of the second coupler 305 and an output signal of the first power divider, Outputs of the first correlator 306 and the first power divider 302 that output a control signal that adjusts the first phase shifter 307 and the first variable attenuator 308 to analyze the correlation to minimize the ID signal. And the output of the second coupler 305 is applied to the first correlator 306 In accordance with the control signal of the first delay line 304, the auxiliary antenna 500 for receiving the transmission feedback signal from the transmission antenna 100, and the first correlator 306 to equalize the phase and magnitude of the transmission feedback signal. A third coupler 311 coupling the signal received by the first phase shifter 307, the first variable attenuator 308, and the reception antenna 200 to be varied, and the transmission feedback signal output from the first variable attenuator 308; And a second delay line 309 and a third delay line 310 for equally adjusting time delays of the reception signal and the transmission feedback signal of the reception antenna 200. 3 illustrates the reception antenna 200, the transmission antenna 100, and the repeater 400 for convenience of description.

Referring to the operation of the transmission feedback signal removal device configured as described above in detail as follows.

The receiving antenna 200 receives the original received signal and the feedback signal of the transmitting antenna 100 at the same time, and the output signal of the receiving antenna 200 is applied to the third delay line 310. The auxiliary antenna 500 is installed at a position similar to the receiving antenna 200, and since the auxiliary antenna 500 has directivity in the direction of the transmitting antenna 100, the original receiving signal and the transmitting feedback signal, such as the receiving antenna 200, simultaneously support the auxiliary antenna 500. Is applied. However, since the original received signal applied to the auxiliary antenna 500 is small enough to be ignored compared to the transmission feedback signal, it can be assumed that only the transmission feedback signal exists in the output signal of the auxiliary antenna 500. The output signal of the auxiliary antenna 500 passes through the first phase shifter 307, the first variable attenuator 308, and the second delay line 309, and the transmission feedback signal applied to the reception antenna 200 has a magnitude. The phase is adjusted to be 180 degrees out of phase.

When the signal having the same magnitude as that of the transmission feedback signal applied to the reception antenna 200 and having a phase difference of 180 ° is coupled with the reception signal including the transmission feedback signal through the third coupler 311, the third coupler 311 ), Only the original signal from which the transmission feedback signal has been removed is output. Therefore, the transmission feedback signal is removed from the signals applied to the third coupler 311 from the reception antenna 200 and the auxiliary antenna 500 at the output of the third coupler 311 and only the original reception signal is present.

Meanwhile, the transmission feedback signal includes an amplified original received signal and an ID signal, and the first correlator 306 uses the first phase converter 307 and the first phase converter so that the ID signal input through the second coupler 305 is minimized. One variable attenuator 308 is controlled. Since the ID signal has a small frequency difference from the original input signal, the removal amount of the ID signal is similar to that of the transmission feedback signal induced by the reception antenna 200. In addition, the delay time from the transmitting antenna 100 to the third coupler 311 after passing through the receiving antenna 200 and the third delay line 310, and the auxiliary antenna 500 from the transmitting antenna 100 After passing through the first phase shifter 307, the first variable attenuator 308, and the second delay line 309, the second delay line (eg, the delay time until the output from the third coupler 311) becomes the same ( 309 and the third delay line 310 may be adjusted, thereby removing the transmission feedback signal in a wide frequency range.

The method for adjusting the delay time is first set such that (the delay time of the third delay line)> (the delay time of the second delay line + the delay time of the first phase shifter and the first variable attenuator), and then the second delay line. By adjusting the delay time of 309, the time delays of the receiving antenna 200 path and the auxiliary antenna 500 path are equally adjusted.

Meanwhile, the first correlator 306 of FIG. 3 may be implemented by the digital controller 600, which is illustrated in FIG. 4.

As shown in FIG. 4, the digital controller 600 detects only an ID signal from an output signal of the repeater 400 output through the second coupler 305 and according to the magnitude of the detected ID signal. A power detector 602 for generating an analog voltage, an A / D converter 603 for converting an analog voltage generated by the power detector into a digital signal, and a controller for controlling the variable attenuator and phase converter so that an ID signal has a minimum size ( 604, first and second D / A converters 605 and 606 for converting a signal of the controller into an analog signal. On the other hand, unlike the first correlator 306, which is an analog correlator, the digital controller controls the first variable attenuator 308 and the first phase shifter 307 by using absolute magnitude information of a previously stored ID signal. When used, the first delay line 304 of FIG. 3 is unnecessary.

The above-described transmission feedback removing device is an example of a device for removing a transmission feedback signal when the frequency characteristic is good, and a time difference between the first transmission feedback signal and the second transmission feedback signal reaching the reception antenna 200 may vary. In this case (a few us), since the magnitude difference between the first transmission feedback signal and the second transmission feedback signal is large, the influence of the second transmission feedback signal can be ignored.

However, although there is a time difference between the second transmission feedback signal and the first transmission feedback signal due to the surrounding environment of the repeater 400, if the difference in signal strength is similar to 10 dB or less, the influence of the second transmission feedback signal cannot be ignored. .

5 is an embodiment of a transmission feedback signal removing device for a case where the transmission feedback signal has two independent paths as described above.

In general, different paths mean different time delays. Therefore, to remove the transmission feedback signal having two independent paths, a correlator, a phase shifter, a variable attenuator, and a delay line for each path are required.

That is, as illustrated in FIG. 5, the ID signal generator 301 and the ID signal generating an ID signal which is a reference signal for detecting the magnitude and phase of the signal fed back from the transmission antenna 100 to the reception antenna 200. A first power divider 302 that distributes the output of the generator 301, a first coupler 303 that couples the output signal of the first power divider 302 and the output signal of the repeater 400, and the repeater 400. The output signal of the second and fourth couplers 305 and 315 and the second coupler 305 and the output signal of the first power divider 302 coupling the output signal and the ID signal of Analyze the output signal of the first correlator 306 and the fourth coupler 311 and the first signal to output a control signal for adjusting the first phase shifter 307 and the first variable attenuator 308 to minimize the ID signal. In order to minimize the ID signal by receiving the output signal of the power splitter 302 and correlating the two signals The output of the second correlator 316, the first power divider 302, and the output of the second coupler 305, which outputs a control signal for adjusting the second phase converter 317 and the second variable attenuator 318, The same time that the output of the first delay line 304 and the first power divider 302 and the output of the fourth coupler are applied to the second correlator 316 is equal to the time applied to the first correlator 306. A fourth delay line 314 for transmitting the auxiliary antenna 500 for receiving a transmission feedback signal from the transmitting antenna 100, a second power divider 320 for distributing an output signal of the auxiliary antenna 500, and a first According to control signals of the first phase shifter 307, the first variable attenuator 308, and the second correlator 316 varying the phase and magnitude of the transmission feedback signal of the first path according to the control signal of the correlator 306. A second phase shifter 317 and a second variable attenuator 318 for varying the phase and magnitude of the transmit feedback signal of the second path; A third coupler 311 coupling the signal received from the tena 200 and the signal output from the first variable attenuator 308, and an output from the signal received from the receiving antenna 200 and the second variable attenuator 318. Second, third, and fifth delay lines for equally adjusting time delays of the first signal and the second path signal of the fifth coupler 321 and the receiving antenna 200 to couple the signal to be coupled ( 309, 310, 319).

The first correlator 306 controls the first phase shifter 307 and the first variable attenuator 308 to minimize the magnitude of the ID signal passing through the first path in free space, and the second correlator 316 The second phase shifter 317 and the second variable attenuator 318 are controlled to minimize the magnitude of the ID signal passing through the second path. In addition, the first power divider 302 distributes the power of the ID signal and sends it to the first coupler 303, the first and fourth delay lines 304 and 314.

In addition, the delay time from the transmitting antenna 100 to the third and fifth couplers 311 and 321 after passing through the receiving antenna 200 and the third delay line 310, and from the transmitting antenna 100 The second and third delay lines 309 and 310 and the fifth delay line 319 are adjusted so that the delay times of the signals passing through the auxiliary antenna 500 and passing through the first and second paths are the same. It is possible to eliminate the transmission feedback signal over a wide frequency range. The delay time adjusting method is the same as the transmission feedback cancellation apparatus of FIG. 3.

The drawings and detailed description of the invention are merely exemplary of the invention, which are used for the purpose of illustrating the invention only and are not intended to limit the scope of the invention as defined in the appended claims or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, when the transmission feedback signal removing device according to the embodiment of the present invention is used, the transmission feedback signal can be removed to prevent oscillation of the same frequency repeater, thereby having a wide frequency characteristic, thereby increasing the capacity of the entire system. There is.

In addition, since the magnitude and phase of the transmission feedback signal are controlled through the ID signal, it is possible to actively compensate for environmental changes.

Claims (9)

In the transmission feedback signal removal device is connected to a repeater for relaying signals where radio waves are not reached in a wireless communication system to remove a part of a signal radiated from the transmitting antenna of the repeater to the receiving antenna. An ID signal generator for generating an ID signal which is a reference signal for removing the transmission feedback signal; A first power divider distributing power of an output signal of the ID signal generator; A second coupler detecting an ID signal from an output signal of the repeater; A first coupler coupling the output signal of the second coupler and the output signal of the first power divider; A first correlator for analyzing a correlation between an output signal of the second coupler and an output signal of the first power divider and outputting a control signal for minimizing the magnitude of the ID signal; An auxiliary antenna for receiving a signal from the transmitting antenna and a transmitting feedback signal flowing into the receiving antenna at a position similar to the receiving antenna; A first phase converter configured to receive an output signal of the first correlator as a control signal and adjust a phase of a transmission feedback signal introduced through the auxiliary antenna; A first variable attenuator receiving the output signal of the first correlator as a control signal and adjusting the magnitude of the output signal of the first phase shifter; A third delay line connected to the reception antenna to adjust a delay time of a signal received from the reception antenna; The transmission feedback signal is removed from the reception signal input to the reception antenna by coupling a signal output through the first variable attenuator to the reception signal passing through the third delay line connected to the third delay line. A third coupler for applying a signal as an input signal of the repeater; And A delay time inserted between the third coupler and the first variable attenuator and passing through the auxiliary antenna, the first phase shifter and the first variable attenuator from the transmitting antenna and outputting a signal from the third coupler; A second delay line configured to equalize a delay time from a transmitting antenna to the receiving antenna and a third delay line to output a signal from the third coupler Transmission feedback signal removal device comprising a. The method of claim 1, The first correlator is an analog correlator, A signal inserted into the first correlator between the first power divider and the first correlator and through the first coupler, the transmit antenna, the receive antenna, the third delay line, the third coupler, the repeater and the second coupler; Delay line for inputting a delay time inputted to the first correlator to the first correlator through the first power divider Transmission feedback signal removal device further comprising. The method of claim 1, The first correlator, Outputs the control signals of the first phase shifter and the first variable attenuator so that a signal passing through the first phase shifter and the first variable attenuator is equal in magnitude to the transmission feedback signal introduced into the reception antenna and is 180 ° out of phase. doing Transmission feedback signal removal device. The method of claim 1, The first correlator, A first filter receiving the output signal of the second coupler and detecting only an ID signal; A first power detector configured to generate an analog voltage according to the magnitude of an ID signal which is an output signal of the first filter; A first analog to digital (AD) converter for converting the analog voltage into a digital signal; A first controller receiving the output signal of the first AD converter and outputting control signals of the first phase converter and the first variable attenuator so that the magnitude of the ID signal is minimized; A first digital to analog (DA) converter connected between the first controller and the first phase shifter and converting a digital signal for controlling the first phase shifter output from the first controller into an analog control signal; And  A second DA converter connected between the first controller and the first variable attenuator and converting a digital signal for controlling the first variable attenuator output from the first controller into an analog control signal; Transmission feedback signal removal device comprising a. The method of claim 1, A fourth coupler which receives the output signal of the second coupler and detects the output signal of the repeater; A second correlator configured to analyze a correlation between an output signal of the fourth coupler and an output signal of the first power divider and output a control signal to minimize an ID signal; A second power divider connected between the auxiliary antenna and the first phase shifter and distributing power of a signal output from the auxiliary antenna; A second phase converter configured to receive an output signal of the second correlator and adjust a phase of a second transmission feedback signal introduced through the second power divider; A second variable attenuator connected between the second correlator and the second phase shifter and configured to receive an output signal of the second correlator and adjust a magnitude of a second transmission feedback signal introduced through the second power divider; A fifth coupler coupling the received signal of the receiving antenna and the signal output through the second variable attenuator; And A delay inserted between the fifth coupler and the second variable attenuator and passing through the auxiliary antenna, the second phase shifter and the second variable attenuator from the transmitting antenna and outputting a signal from the output terminal of the fifth coupler; A fifth delay line equaling a time from the transmitting antenna to the receiving antenna, the third delay line, and the third coupler to output a signal from an output terminal of the fifth coupler; Transmission feedback signal removal device further comprising. The method of claim 5, The second correlator is an analog correlator, It is inserted between the first power divider and the second correlator, and passes through the first coupler, the transmit antenna, the receive antenna, the third delay line, the third coupler, the fifth coupler, the repeater, the second coupler, and the fourth coupler. A fifth delay line for equalizing a delay time at which a signal is input to the second correlator and a delay time at which the ID signal is input to the second correlator through a first power divider Transmission feedback signal removal device further comprising. The method of claim 5, The second correlator, Control signals of the second phase shifter and the second variable attenuator such that a signal passing through the second phase shifter and the second variable attenuator is equal in magnitude to the second transmission feedback signal introduced into the reception antenna and is 180 ° out of phase. To output Transmission feedback signal removal device. The method of claim 5, The second correlator, A second filter receiving the output signals of the second power divider and the fourth coupler and detecting only an ID signal; A second power detector for generating an analog voltage according to the magnitude of an ID signal which is an output signal of the second filter; A second AD converter for converting an analog voltage, which is an output of the second power detector, into a digital signal; A second controller receiving the output signal of the second AD converter and outputting control signals of the second phase converter and the second variable attenuator; A third DA converter for converting a digital signal for controlling the second phase converter output from the second controller into an analog control signal; And A fourth DA converter for converting a digital signal for controlling the second variable attenuator output from the second controller into an analog control signal Transmission feedback signal removal device comprising a. In the relay system of the wireless communication system, A repeater for amplifying a signal received by the reception antenna and transmitting the result to the outside through the transmission antenna; And Transmission feedback signal removing device for removing a part of the signal emitted from the transmission antenna of the repeater to the transmission feedback signal flowing into the receiving antenna Including; The transmission feedback signal removal device,  An ID signal generator for generating an ID signal which is a reference signal for removing the transmission feedback signal; A first power divider distributing power of an output signal of the ID signal generator; A second coupler detecting an ID signal from an output signal of the repeater; A first coupler coupling the output signal of the second coupler and the output signal of the first power divider; A first correlator for analyzing a correlation between an output signal of the second coupler and an output signal of the first power divider and outputting a control signal for minimizing the magnitude of the ID signal; An auxiliary antenna for receiving a signal from the transmitting antenna and a transmitting feedback signal flowing into the receiving antenna at a position similar to the receiving antenna; A first phase converter configured to receive an output signal of the first correlator as a control signal and adjust a phase of a transmission feedback signal introduced through the auxiliary antenna; A first variable attenuator receiving the output signal of the first correlator as a control signal and adjusting the magnitude of the output signal of the first phase shifter; A third delay line connected to the reception antenna to adjust a delay time of a signal received from the reception antenna; The transmission feedback signal is removed from the reception signal input to the reception antenna by coupling a signal output through the first variable attenuator to the reception signal passing through the third delay line connected to the third delay line. A third coupler for applying a signal as an input signal of the repeater; And A delay time inserted between the third coupler and the first variable attenuator and passing through the auxiliary antenna, the first phase shifter and the first variable attenuator from the transmitting antenna and outputting a signal from the third coupler; A second delay line configured to equalize a delay time from a transmitting antenna to the receiving antenna and a third delay line to output a signal from the third coupler Relay system comprising a.

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