KR100326275B1 - Apparatus for removing interference signal in radio communication system - Google Patents

Abstract

Disclosed is an interference canceling device in a wireless communication system. In the wireless communication system, an interference signal removing apparatus according to the present invention, which removes a part of a signal transmitted through a transmitting antenna from a receiving antenna, receives a transmission signal to be transmitted through a transmitting antenna and transmits the received signal to a surrounding environment of a transmitting / receiving antenna. Attenuating signal generator that generates attenuated signals by controlling a transmission signal in response to a control signal to have an amplitude and a phase equal to a time-varying interference signal, and extracts only a desired signal by subtracting an attenuated signal from a signal received from a receiving antenna, A subtractor for outputting the extracted signal as a received signal, and a control signal generator for mixing a received signal and a tracer signal to generate a direct current signal representing a degree of the interference signal remaining in the received signal as a control signal; Close to the information signal and information signal to be transmitted It characterized in that it comprises a tracer having a wave number, and can therefore track the interference signal is changed according to the ambient environment of the antenna by using the tracer signal, removing the interference signal effectively. In addition, when the interference signal removing device in the wireless communication system according to the present invention is applied to the wireless communication system, it is not affected by the interference signal so that the communication quality can be improved and the maintenance cost of the wireless communication system can be reduced. have.

Description

Apparatus for removing interference signal in radio communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and in particular, due to the combination of a transmit / receive antenna, a part of a signal transmitted from a transmit antenna adaptively removes an interference signal introduced into a receive antenna according to a change in an interference signal. An interference signal cancellation apparatus in a communication system.

For example, the wireless repeater receives a signal weakened while being transmitted through the wireless transmission path through the receiving antenna, and then amplifies the signal of the same frequency and retransmits it through the transmitting antenna. At this time, a part of the signal transmitted through the transmitting antenna is re-received as an interference signal through the receiving antenna. At this time, the interference signal has the same frequency as the signal received from another wireless repeater or base station. This interference signal provides a cause for the amplifier to self-oscillate while the wireless repeater amplifies and retransmits the received signal.

FIG. 1 is a diagram illustrating a general wireless repeater, and illustrates a base station antenna 10, a reception antenna 12 of a wireless repeater, and a transmission antenna 14 of a wireless repeater.

Referring to FIG. 1, the reception signal R_SIG transmitted from the base station antenna 10 and received by the reception antenna 12 of the wireless repeater is weakened while being transmitted through the wireless transmission path. The receiving antenna 12 of the wireless repeater receives the weakened reception signal R_SIG, amplifies the signal having the same frequency, and outputs the same through the transmitting antenna 14 of the wireless repeater. At this time, some of the signals transmitted from the transmitting antenna 14 of the wireless repeater are fed back to the receiving antenna 12 of the wireless repeater as an interference signal S _L.

On the other hand, if the gain of the amplifier in the wireless repeater to amplify the received signal received from the receiving antenna 12 is large, long distance communication is possible, it is possible to reduce the number of wireless repeaters on the wireless transmission path. However, when the gain of the amplifier is high, the amplifier can self oscillate due to the interference signal S _L fed back from the transmitting antenna 14, so that the gain of the amplifier is limited.

As a passive method of reducing the interference of the interference signal (S _L ) in the wireless repeater, there is a method of reducing the interference signal (S _L ) flowing from the transmitting antenna to the receiving antenna by sufficiently securing the distance of the transmitting / receiving antenna of the wireless repeater. . However, this method can simply reduce the interference signal S _L flowing into the receiving antenna and is difficult to eliminate completely. In addition, when the distance between the transmitting and receiving antennas of the wireless repeater is far, maintenance and repair of the wireless repeater becomes difficult.

An object of the present invention is to provide an interference signal removing apparatus in a wireless communication system that effectively removes an interference signal of the same frequency in a wireless communication system.

1 is a view for explaining a general wireless repeater.

2 is a block diagram schematically illustrating an interference signal removing apparatus in a wireless communication system according to the present invention.

3 is a block diagram schematically illustrating an embodiment of the attenuation signal generator 20 shown in FIG. 2.

FIG. 4 is a circuit diagram illustrating in detail each part of the attenuation signal generator shown in FIG. 3.

FIG. 5 is a graph illustrating reflection gain and phase control of the first to fourth pin diodes PIN_D1 to PIN_D4 constituting the first and second attenuators 32 and 34 shown in FIG. 4.

FIG. 6 is a circuit diagram illustrating an embodiment of the control signal generator 22 shown in FIG. 2.

7 is a diagram illustrating characteristics of a general pin diode according to a level of a control signal.

8 is a system for simulating an interference signal cancellation apparatus in a wireless communication system according to the present invention.

9A to 9D are diagrams illustrating signal detection results of the spectrum analyzer 176 according to input conditions in the system illustrated in FIG. 8.

In order to achieve the above object, the interference signal removing apparatus according to the present invention for removing a part of the signal transmitted through the transmission antenna in the wireless antenna in the reception antenna in accordance with the present invention receives the transmission signal to be transmitted through the transmission antenna, transmit / An attenuation signal generator which generates attenuation signal by controlling a transmission signal in response to a control signal so as to have an amplitude and a phase equal to an interference signal that varies according to a surrounding environment of the reception antenna, and subtracts the attenuation signal from a signal received from the reception antenna. A subtractor for extracting only a desired signal and outputting the extracted signal as a received signal, and a control signal generator for mixing a received signal and a tracer signal to generate a direct current signal indicating a degree of interference signal remaining in the received signal as a control signal; Information signal to be transmitted And preferably it comprises a tracer having the information signal and the adjacent frequency.

Hereinafter, an interference signal removing apparatus in a wireless communication system according to the present invention will be described with reference to the accompanying drawings.

2 is a block diagram schematically illustrating an interference signal removing apparatus in a wireless communication system according to the present invention. In the wireless communication system according to the present invention, the interference canceling device includes an attenuation signal generator 20, a control signal generator 22, and a subtractor 24. For convenience of explanation, the transmission antenna 26 and the reception antenna 28 are shown together in FIG.

Referring to FIG. 2, the attenuation signal generator 20 receives the transmission signal T_SIG to be transmitted through the transmission antenna 26 and has the same amplitude and phase as the time-varying interference signal S _L. In response to the control signal CNT, the amplitude and phase of the transmission signal T_SIG are controlled. The attenuation signal generator 20 generates an amplitude and phase controlled signal as the attenuation signal AT_SIG. Here, the transmission signal T_SIG includes a signal including information and a tracer signal REF described later. In addition, the attenuation signal generator 20 has an amplitude gain K and a delay time T, and the amplitude gain K and the delay time T may be controlled in response to the control signal CNT.

For example, if the transmission signal T_SIG is defined as in Equation 1 below, the attenuation signal AT_SIG output from the attenuation signal generator 20 in response to the control signal CNT is shown in Equation 2 below.

T_SIG = A (t) sin {ωt + ψ (t)}

Where A (t) represents a time varying amplitude function, ω represents a carrier angular frequency, and ψ represents a time varying phase, respectively.

AT_SIG = KA (t-T) sin {ω (t-T) + ψ (t-T)}

At this time, assuming that the time delay is very small and A (t-T) = A (t) and ψ (t-T) = ψ (t), the attenuation signal AT_SIG may be expressed as in Equation 3 below.

AT_SIG = KA (t) sin {ω (t-T) + ψ (t)}

= KA (t) sin {ω (t) + ψ (t) + θ}

Where θ = −ωT.

As described above, the attenuation signal AT_SIG generated by the attenuation signal generator 20 generates an amplitude gain K and a time delay T in response to the control signal CNT.

The subtractor 24 subtracts the attenuation signal AT_SIG from the signal received from the receiving antenna 28, and generates the subtracted result as a receiving signal R_SIG which is ultimately intended to be received. Here, the interference signal S _L flowing from the transmission antenna 26 and the reception signal R_SIG to be received are present in the signal received from the reception antenna 28. At this time, the attenuation signal AT_SIG is a signal that is controlled to have the same amplitude and phase as the interference signal S _L as described above. Accordingly, when the subtractor 24 shifts the attenuation signal AT_SIG 180 degrees out of phase with the signal received from the receiving antenna 28, the interference signal S _L is removed from the signal received from the receiving antenna 28. The received signal R_SIG can be obtained.

The control signal generator 22 mixes the received signal R_SIG and the tracer signal REF output from the subtractor 28, and the DC signal indicating the degree of the interference signal S _L remaining in the received signal R_SIG. The signal is generated as a control signal CNT. Here, the tracer signal REF is a signal that is used as a reference for the control signal generator 22 to extract the degree of the interference signal S _L remaining from the received signal R_SIG, and is close to a signal including information. It is a signal having. At this time, when the level of the control signal CNT increases, this indicates that the interference signal S _L remaining in the reception signal R_SIG is large, and when the level of the control signal CNT decreases, the residual signal in the reception signal R_SIG Indicates that the interference signal S _L is small. When the interference signal S _L remaining in the received signal R_SIG is completely removed, the signal generator 22 stops tracking the interference signal S _L and fixes the level of the control signal CNT.

As described above, in the interference signal removing apparatus according to the present invention, the control signal generator 22 continuously detects the degree of the interference signal S _L remaining in the received signal R_SIG and attenuates according to the detected result. The signal generator 20 is controlled. Accordingly, the attenuation signal generator 22 may generate an attenuation signal AT_SIG whose amplitude and phase are controlled according to the degree of the interference signal S _L remaining in the reception signal R_SIG. Therefore, the reception signal R_SIG from which the interference signal S _L is removed from the signal received from the reception antenna 28 can be obtained.

In addition, as described above, when the interference signal removing device is applied to the wireless repeater in the wireless communication system, since the interference signal S _L is not affected, the received signal R_SIG amplified by the reception antenna 28 is amplified. The gain of the amplifier inside the wireless repeater is increased so that long-distance communication is possible. Therefore, the number of wireless repeaters on the wireless transmission line can be reduced, thereby reducing costs, and the maintenance of the wireless repeaters becomes easier.

3 is a block diagram schematically illustrating an embodiment of the attenuation signal generator 20 shown in FIG. 2. The attenuation signal generator 20 includes a phase shifter 30, first and second attenuators 32 and 34, and an adder 36.

Referring to FIG. 3, the phase shifter 30 receives the transmission signal T_SIG and generates a transmission signal T_SIG having no phase delay as the first signal SIG1, and transmits the phase-delayed transmission signal T_SIG by 90 °. Are generated as the second signals SIG2, respectively.

The first attenuator 32 attenuates the first signal SIG1 with a gain K1 in response to the first control signal CNT1.

The second attenuator 34 attenuates the second signal SIG2 with a gain K2 in response to the second control signal CNT2.

The adder 36 adds signals output from the first and second attenuators 32 and 34, respectively, and outputs the attenuated signal AT_SIG.

For example, assuming that the transmission signal is equal to Equation 1, the attenuation signal AT_SIG output from the attenuation signal generator shown in FIG. 3 is represented by Equation 4 below. At this time, it is assumed that the time delay is very small and A (t-T) = A (t) and ψ (t-T) = ψ (t).

AT_SIG = K1A (t) sin {ωt + ψ (t)} + K2A (t) sin {ωt + π / 2 + ψ (t)}

= K1A (t) sin {ωt + ψ (t)} + K2A (t) cos {ωt + ψ (t)}

= KA (t) sin {ωt + ψ (t) + θ}

Here, K = √ (K1 ² + K2 ² ), and θ = arc tan (K2 / K1).

As such, by controlling the gains of the first and second attenuators 32 and 34 independently using the first and second control signals CNT1 and CNT2, the amplitude K and the phase θ of the attenuation signal AT_SIG can be controlled. Can be. Here, the first and second control signals CNT1 and CNT2 are control signals generated by the control signal generator 22 shown in FIG. 2. In this case, the first control signal CNT1 is a signal indicating the degree of the interference signal S _L having the same component as the tracer signal REF in the received signal R_SIG. In addition, the second control signal CNT is a signal indicating the degree of the interference signal S _L having the same component as the signal in which the tracer signal REF is phase shifted by 90 ° from the reception signal R_SG.

On the other hand, if K1 and K2 are positive values, the range of phase delay θ obtained from the attenuation signal generator shown in Fig. 3 is tan θ = (K2 / K1), so that 0 ≦ θ ≦ 90 °. However, the range of phase delay θ that should be implemented in the attenuation signal generator shown in FIG. 3 should be 0 ≦ θ ≦ 360 °. Therefore, the gains K1 and K2 of the first and second attenuators 32 and 34 must be controlled to have both positive and negative values.

As described above, the attenuation signal generator shown in FIG. 3 controls the gain characteristics of the first and second attenuators 32 and 34, respectively, in response to the first and second control signals CNT1 and CNT2. Amplitude and phase control of the attenuation signal AT_SIG is possible. In this case, the first and second attenuators 32 and 34 should use a reflective attenuator in which a phase change occurs linearly with a change in gain of the attenuator. For example, the absorption type attenuator causes a nonlinear change in phase due to a change in gain of the attenuator, and thus cannot predict a phase change due to a change in gain of the attenuator. As a result, phase control through gain adjustment of the attenuator is impossible.

FIG. 4 is a circuit diagram illustrating in detail each part of the attenuation signal generator shown in FIG. 3. Referring to FIG. 4, the phase shifter 30 may be implemented with a first hybrid 40 and a matching resistor R9. In addition, the first attenuator 32 may include a second hybrid 42, first and second pin PIN diodes PIN_D1 and PIN_D2, capacitors C1 to C5, inductors L1 and L2, and resistors. It may be implemented as (R1 ~ R3). In addition, the second attenuator 34 may include a third hybrid 44, first and second pin diodes PIN_D3 and PIN_D4, capacitors C7 to C11, inductors L3 and L4, and resistors R4 to R6).

In FIG. 4, the first hybrid 40 is 90 ° hybrid, where the first terminal is connected to the matching resistor R9 and the second terminal is connected to the transmission signal T_SIG. The first hybrid 40 receives the transmission signal T_SIG as the second terminal and outputs the transmission signal T_SIG without a phase delay as the first signal SIG1 through the third terminal. The first signal SIG1 is input to the first terminal of the second hybrid 42 through the capacitor C4. In addition, the first hybrid 40 outputs a signal obtained by delaying the transmission signal T_SIG by 90 ° out of phase as the second signal SIG2 through the fourth terminal. The second signal SIG2 is input to the first terminal of the third hybrid 44 through the capacitor C7.

The first control signal CNT1 input to the first attenuator 32 is noise-removed through the capacitors C1 to C3, the inductors L1 and L2, and the resistors R1 to R3, thereby providing a second hybrid ( 42) are applied to the first and second terminals.

The second hybrid 42 outputs the first control signal CNT1 applied to the first and second terminals to the third and fourth terminals. In addition, the second hybrid 42 receives the first signal SIG1 from the capacitor C4, outputs the first signal SIG to the third terminal as it is, and delays the phase by 90 ° to the fourth terminal. Outputs one signal SIG1. In addition, the second hybrid 42 sums the signals reflected from the first and second pin diodes PIN_D1 and PIN_2 and outputs them to the second terminal.

The anodes of the first and second pin diodes PIN_D1 and PIN_2 are connected to the third and fourth terminals of the second hybrid 42, respectively, and the cathode is grounded. In this case, the first and second pin diodes PIN_D1 and PIN_D2 have resistance values corresponding to the first control signal CNT1. In addition, the first and second pin diodes PIN_D1 and PIN_D2 are reflection gains corresponding to resistance values, and the first signal SIG applied from the third and fourth terminals, respectively, and the first signal SIG1 delayed by 90 °. ).

The second control signal CNT2 input to the second attenuator 34 is noise-removed through the capacitors C9 to C11, the inductors L3 and L4, and the resistors R4 to R6, so that the third hybrid ( 44) is applied to the first and second terminals. Hereinafter, the third hybrid 44 and the third and fourth pin diodes PIN_D3 and PIN_D4 of the second attenuator 34 have the second hybrid 42 and the first and second pin diodes of the first attenuator 32. Corresponds to each of (PIN_D1, PIN_D2) and performs the same operation. Therefore, detailed descriptions of the third hybrid 44 and the third and fourth pin diodes PIN_D3 and PIN_D4 of the second attenuator 34 will be omitted. As a result, the third hybrid 44 sums the signals reflected from the third and fourth pin diodes PIN_D3 and PIN_4 and outputs them to the second terminal.

The adder 36 receives and adds signals output from the second output terminals of the second and third hybrids 42 and 44 from the capacitors C5 and C6, and outputs the added result as an attenuation signal AT_SIG. do.

FIG. 5 is a graph illustrating reflection gain and phase control of the first to fourth pin diodes PIN_D1 to PIN_D4 constituting the first and second attenuators 32 and 34 shown in FIG. 4.

Referring to FIG. 5, the vertical axis represents the level of the second control signal CNT2, and the horizontal axis represents the level of the first control signal CNT1. Each concentric circle represents the levels of the first and second control signals CNT1 and CNT2 for the same amount of attenuation. For example, when the resistance of the pin diodes constituting the first and second attenuators 32 and 34 is 50 ohms or less, the reflection gain coefficient of the attenuator becomes negative and the phase changes from -180 ° to 0 °. do. In addition, when the resistance of the pin diodes constituting the first and second attenuators 32 and 34 is 50 ohms or more, the reflection gain coefficient of the attenuator becomes a positive value and the phase changes from 0 ° to 180 °. . As a result, phase control may be performed by gain coefficient control of the first to fourth pin diodes PIN_D1 to PIN_D4 by the first and second control signals CNT1 and CNT2.

FIG. 6 is a circuit diagram illustrating an embodiment of the control signal generator 22 shown in FIG. 2. The control signal generator 22 includes a voltage divider 60, an error extractor 80, first and second integrators 68 and 70, first and second adders 72 and 74, and first and second operations. And two logarithmic amplifiers 76 and 78 and resistors R1 to R4.

Referring to FIG. 6, the voltage divider 60 distributes the received signal R_SIG to generate a first divided signal and a second divided signal.

The error extracting unit 80 generates the first and second reference signals REF1 and REF2 by delaying the tracer signal REF to 0 ° and 90 °, respectively. In addition, the error extracting unit 80 mixes each of the first and second reference signals REF1 and REF2 and the reception signal R_SIG, and outputs the mixed result as the first and second error signals ERR1 and ERR2. do. At this time, the first error signal ERR1 is a result of mixing of the reception signal R_SIG and the first reference signal REF1, and the interference signal having the same component as the first reference signal REF1 in the reception signal R_SIG. The residual degree of (S _L ) is shown. In addition, the second error signal ERR2 is a result of mixing of the received signal R_SIG and the second reference signal REF2, and the interference signal having the same component as the second reference signal REF2 in the received signal R_SIG. The residual degree of S _L ) is shown.

The first and second integrators 68 and 70 integrate the first and second error signals ERR1 and ERR2, respectively.

The first and second adders 72 and 74 add the supply power supply Vc to the result of integration in the first and second integrators 68 and 70, thereby integrating in the first and second integrators 68 and 70. All results are shifted to positive levels. As a result of integrating the first and second integrators 68 and 70, the first and second control signals for controlling the attenuation amount of the attenuators constituting the attenuation signal generator, as shown in FIG. It is used as (CNT1, CNT2). That is, the first and second control signals CNT1 and CNT2 are used as control signals for controlling the pin diodes, but it is inappropriate to control the pin diodes with a control signal having a negative level. Accordingly, the integrated results in the first and second integrators 68 and 70 using the first and second adders 72 and 74 can all be shifted to positive levels.

When the first and second logarithmic amplifiers 76 and 78 implement the attenuators used in the attenuation signal generator shown in FIG. 4 as pin diodes, the attenuation characteristics of the pin diode corresponding to the control signal have a linear characteristic. do. In this way, if the attenuation characteristic of the pin diode has a linear characteristic, the gain control of the pin diode can be more precisely controlled.

7 is a diagram illustrating characteristics of a general pin diode according to a level of a control signal.

As shown in FIG. 7, the attenuation characteristic of the pin diode has a nonlinear characteristic corresponding to the level of the control signal, as shown in the first graph (a). The first and second logarithmic amplifiers 76 and 78 have first and second control signals CNT1 and CNT2 such that the attenuation characteristics of the attenuators shown in FIG. 4 may have linear characteristics, as shown in the second graph (b). To control.

Referring to FIG. 6, the error extractor 80 includes a phase shifter 66, first and second mixers 62 and 64, first and second low pass filters 86 and 88, and amplifiers 82. 84).

The phase shifter 66 receives the trace signal REF and converts the tracer signal REF without phase delay into the first reference signal REF1 and the tracer signal REF delayed by 90 ° in phase with the second reference signal ( REF2) respectively.

The first mixer 62 mixes the first divided signal and the first reference signal REF1. The first low pass filter 86 low-pass filters the signal output from the first mixer 62 to extract a DC component. At this time, the signal output from the first low pass filter 86 indicates the residual degree of the interference signal S _L having the same component as the first reference signal REF1 in the received signal R_SIG. The signal output from the first low pass filter 86 is input to the amplifier 82 through the resistor R1, amplified, and then output as a first error signal ERR1.

The second mixer 64 mixes the second divided signal and the second reference signal REF2. The second low pass filter 88 low-pass filters the signal output from the second mixer 64 to extract a DC component. At this time, the signal output from the second low pass filter 88 indicates the residual degree of the interference signal S _L having the same component as the second reference signal REF2 in the received signal R_SIG. The signal output from the second low pass filter 88 is input to the amplifier 82 through the resistor R2, amplified, and then output as a second error signal ERR2.

Subsequently, the first integrator 68 may be implemented with resistors R5 and R6 and amplifier 90, and the second integrator 70 may be implemented with resistors R3 and R4 and amplifier 92. Can be.

In addition, the first adder 72 may be implemented by the resistors R10 to R12 and the amplifier 94, and the second adder 74 may be implemented by the resistors R7 to R9, respectively.

In addition, the first logarithmic amplifier 76 may include diodes D1 and D2, resistors R13 to R19, and an amplifier 98. The second logarithmic amplifier 76 controls the turn-on / turn-off of the diodes D1 and D2 according to the level of the signal generated by the first adder 74 by varying the bias resistance of the diodes D1 and D2. do. As such, the gain of the first logarithmic amplifier 76 is controlled through the turn-on / turn-off control of the diodes D1 and D2.

In addition, the second logarithmic amplifier 78 may include diodes D3 and D4, resistors R20 to R26, and an amplifier 100. The second logarithmic amplifier 78 controls the turn-on / turn-off of the diodes D3 and D4 according to the level of the signal generated by the second adder 76 by varying the bias resistance of the diodes D3 and D4. do. As such, the gain of the second logarithmic amplifier 78 is controlled through the turn-on / turn-off control of the diodes D3 and D4.

As such, the first and second logarithmic amplifiers 76 and 78 vary the bias resistances of the diodes constituting the first and second logarithmic amplifiers 76 and 78, thereby attenuating the pin diode as shown in FIG. The gain of the first and second logarithmic amplifiers can be controlled so that the characteristic is linearized.

In the wireless communication system described above, the interference signal canceling device includes an antenna side-lobe remover, an interference cancellation between the wireless systems, a transponder in a radar system, a multipath fading remover, a wireless caller and a wireless repeater for a mobile phone. It can be used variously to remove the interference signal from the back.

8 is a system for simulating an interference signal cancellation apparatus in a wireless communication system according to the present invention.

2 and 8, the voltage dividers 118-124, the switches 158-168, and the phase shifters 152-156 simulate an environmental change between the transmit / receive antenna, The path of the interference signal S _L input to the receiving antenna 28 was set to three paths. The first path path1 represents an interference signal flowing directly from the transmitting antenna 26 to the receiving antenna 28, and the second and third paths path2 and path3 represent the periphery of the transmitting / receiving antennas 26 and 28. The interference signal reflected from the object and introduced into the reception antenna 26 is shown. That is, the signal received from the coupler 170 to the voltage divider 124 generates an interference signal S _L through a predetermined path in response to the switching operation of the switches 158 to 168 and outputs the interference signal S _L to the adder 112. do.

The signal generated at the oscillator 110 is a signal having ultimately information to be obtained and represents a signal received from the base station.

The adder 112 adds the signal generated by the mixer 110 and the signal generated by the interference signal generator 200 to generate a signal including the interference signal in the signal received from the base station. That is, the signal received by the receive antenna 28 of FIG. 2 is implemented.

The subtractor 154 subtracts the attenuation signal AT_SIG generated by the attenuation signal generator 152 from the signal output from the adder 112. As described above, since the attenuation signal AT_SIG is a signal whose amplitude is controlled to be in phase with the interference signal S _L , the signal output from the subtractor 154 is a signal from which the unwanted interference signal S _L has been removed. The signal R_SIG is output to the voltage divider 116.

The voltage divider 116 divides the signal output from the subtractor 116 and outputs the signal to the amplifiers 134 and 138, respectively. In FIG. 8, the amplifiers 134, 136, the bandpass filter 140, the voltage dividers 180, 182, 130, the signal separators 146, 148, the coupler 172, the adder 182, and the mixer 174 are shown in FIG. 2. Implement the transmission signal T_SIG transmitted in 26).

Specifically, the amplifiers 134 and 136 amplify the received signal R_SIG from which the interference signal S _L has been removed, and then pass-band filter the band pass filter 140. The voltage divider 180 distributes the signal passing through the band pass filter 140 to the adder 132 and the signal separator 146, respectively.

The oscillator 174 generates a tracer signal REF having a frequency close to that generated by the mixer 110 and outputs it to the voltage divider 128. The voltage divider 128 distributes the tracer signal REF generated by the mixer 174 to the control signal generator 150 and the signal separator 148, respectively.

The voltage divider 130 distributes the tracer signal REF received from the signal separator 148 to the adders 182 and 132, respectively.

As a result, the adder 182 outputs the signal obtained by adding the tracer signal REF to the signal received from the signal separator 146 to the spectrum analyzer 176 through the coupler 172 as the transmission signal T_SIG. In addition, the adder 132 outputs a signal obtained by adding the tracer signal REF to the received signal distributed from the signal divider 180, to the attenuation signal generator 152.

Meanwhile, as described above, the transmission signal T_SIG is attenuated by the couplers 172 and 170 and then output to the voltage divider 124. Here, the couplers 172 and 170 are implemented in that the amplitude is attenuated while flowing from the transmit antenna 26 to the receive antenna 28 in FIG. In the actual simulation, the attenuation of the transmission signal T_SIG by the couplers 172 and 170 is about 40 dB, which is a case where the distance between the transmission antenna and the reception antenna is about 1 m.

Meanwhile, the amplifier 138 amplifies the received signal R_SIG, and the voltage divider 126 distributes the signal amplified by the amplifier 138 to generate the first and second divided signals. The signal separators 142 and 144 transmit the first and second distribution signals to the control signal generator 150. The control signal generator 150 receives the first and second divided signals and the tracer signal REF from the voltage divider 128 and through the operation of the control signal generator as described with reference to FIG. Generates two control signals CNT1 and CNT2.

The attenuation signal generator 152 controls the amplitude and phase of the signal received from the adder 132 to be equal to the interference signal S _L , in correspondence to the first and second control signals, and controls the controlled signal to the attenuation signal. Output to subtractor 154 as (AT_SIG).

9A to 9D are diagrams illustrating signal detection results of the spectrum analyzer 176 according to input conditions in the system illustrated in FIG. 8.

9A to 9C illustrate the path of the interference signal S _L flowing into the adder 112 after operating the oscillator 174 without operating the oscillator 110 in the apparatus shown in FIG. 8. When changed to the third paths path1 to path3, the spectra detected by the spectrum analyzer 176 are respectively shown.

FIG. 9A illustrates a case in which an interference signal S _L flowing into the adder 112 flows through a first path 1, and FIG. 9B illustrates an interference signal through a first path 2 and a path 2. The spectrum detected by the spectrum analyzer 176 when (S _L ) flows in is shown. In addition, FIG. 9C illustrates a spectrum detected by the spectrum analyzer 176 when the interference signal S _L is introduced through the first to third paths path1 to path3.

9A to 9C, in the spectrum detected by the spectrum analyzer 176, the interference signal S _L is all removed, and only the frequency spectrum of the tracer signal REF is displayed.

FIG. 9D illustrates operating the oscillators 110 and 174, allowing the interference signal S _L to flow through the first to third paths path1 to path3, and then varying the level of the signal generated by the oscillator 110. In this case, the spectrum detected by the spectrum analyzer 176 is shown. Referring to FIG. 9D, the spectrum shown on the left is for the tracer signal REF and the spectrum shown on the right is for the signal generated by the oscillator 110. As a result, the level of the spectrum detected by the spectrum analyzer 176 only changes according to the level of the signal generated by the oscillator 110, and there is no spectrum for the interference signal S _L.

As a result, it can be seen that the interference signal S _L is effectively removed through the interference signal removing apparatus in the wireless communication system according to the present invention.

As described above, in the wireless communication system according to the present invention, since the interference signal removing apparatus tracks the interference signal that changes according to the surrounding environment of the antenna using the tracer signal, the interference signal can be effectively removed. In addition, when the interference signal removing device in the wireless communication system according to the present invention is applied to the wireless communication system, it is not affected by the interference signal so that the communication quality can be improved and the maintenance cost of the wireless communication system can be reduced. have.

Claims (7)

An interference signal removing apparatus for removing a portion of a signal transmitted through a transmission antenna in a wireless communication system to the reception antenna, An attenuation signal generated as an attenuation signal by receiving the transmission signal to be transmitted through the transmission antenna and controlling the transmission signal in response to a control signal so as to have the same amplitude and phase as the interference signal that varies according to the surrounding environment of the transmission / reception antenna. Generator; A subtractor which subtracts the attenuation signal from the signal received from the receiving antenna to extract only a desired signal and outputs the extracted signal as a received signal; And A control signal generator that mixes the received signal and the tracer signal and generates a direct current signal indicating a degree of the interference signal remaining in the received signal as a control signal, And the transmission signal comprises an information signal to be transmitted and the tracer having a frequency close to the information signal. The method of claim 1, wherein the attenuation signal generating unit A phase shifter which receives the transmission signal and generates a transmission signal which has not been phase delayed as a first signal and a transmission signal having a phase delay of 90 ° as a second signal, respectively; A first attenuator for attenuating said first signal with a first gain corresponding to a first control signal; A second attenuator for attenuating said second signal with a second gain corresponding to a second control signal; And An adder for adding signals output from the first and second attenuators, respectively, and outputting the signals as the attenuation signals; The first control signal is a signal representing the degree of interference signal having the same component as the tracer signal in the received signal, and the second control signal is a component such as a signal in which the tracer signal is shifted by 90 ° in the received signal. Apparatus for removing interference signal in a wireless communication system, characterized in that the signal indicating the degree of the interference signal having a. The interference signal of claim 2, wherein the first and second attenuators are reflection attenuators in which a phase change occurs linearly with a gain change corresponding to the first and second control signals. Removal device. The method of claim 2, wherein the first attenuator Each cathode is grounded, and includes first and second pin diodes for reflecting a signal input to each anode with a gain corresponding to the first and second control signals; And The first terminal receives the first signal as a first terminal, and outputs the first signal as it is to the third terminal connected to the anode of the first pin diode, and the fourth terminal connected to the anode of the second pin diode is A first hybrid which generates a signal having a phase delayed by 90 ° of the first signal, and outputs a signal reflected from the first and second pin diodes and outputs the second signal connected to the adder; The second attenuator Each cathode is grounded, and includes third and fourth pin diodes for reflecting a signal input to each anode with a gain corresponding to the first and second control signals; And The second terminal receives the second signal as a first terminal, and outputs the second signal as it is to the third terminal connected to the anode of the third pin diode, and the fourth terminal connected to the anode of the fourth pin diode is And a second hybrid for generating a signal having a phase delayed by 90 ° from the second signal, and outputting the signals reflected from the third and fourth pin diodes to the second terminal connected to the adder. Apparatus for eliminating interference signals in a wireless communication system. The method of claim 1, wherein the control signal generator A voltage divider configured to distribute the received signal to generate a first divided signal and a second divided signal; Phase-delay the tracer signal at 0 ° and 90 °, respectively, to obtain first and second reference signals, and mix the first and second reference signals with the received signal, respectively, to achieve the same as the first and second reference signals. An error extraction unit for extracting a residual degree of the interference signal with respect to the frequency component as the first and second error signals; First and second integrators for integrating the first and second error signals, respectively; And By adding supply power to the integrated results in the first and second integrators, the integrated results in both the first and second integrators are shifted to a positive level, and the transitioned results are controlled by the first and second controls. And a first adder and a second adder for outputting the signal as a signal. The method of claim 5, wherein the control signal generator And first and second logarithmic amplifiers for controlling the first and second control signals such that the attenuation characteristics of the attenuation signal generator have linear characteristics in response to the first and second control signals. Apparatus for eliminating interference signals in a wireless communication system. The method of claim 5, wherein the error signal extraction unit A second phase shifter which receives the trace signal and generates a tracer signal without phase delay as the first reference signal and a tracer signal delayed by 90 ° as the second reference signal, respectively; A first mixer for mixing the first divided signal and the first reference signal; A first low pass filter for low-pass filtering the signal output from the first mixer and extracting a degree of an interference signal having the same frequency as the first reference signal from the first divided signal as a direct current signal; A first amplifier amplifying a signal output from the first low pass filter and outputting the first error signal as the first error signal; A second mixer for mixing the second divided signal and a second reference signal; A second low pass filter for low-pass filtering the signal output from the second mixer and extracting a degree of an interference signal having the same frequency as the second reference signal from the second divided signal as a direct current signal; And And a second amplifier configured to amplify the signal output from the second low pass filter and output the second signal as the second error signal.