KR100388800B1 - Method and apparatus for removing a feedback signal of RF repeater - Google Patents

Abstract

Method for preventing oscillation of the RF repeater that can prevent the oscillation caused by the echo signal of the RF repeater by controlling the size of the signal output from the RF repeater transmitting the signal received from the base station to the mobile terminal at all times An apparatus is disclosed. The base station signal, the echo signal, and the phase shift signal introduced into the repeater through the base station antenna are mixed in the first coupler and applied to the low noise amplifier. The low noise amplifier amplifies the signal and is applied to the signal coupler second coupler through the first intermediate frequency converter and the second intermediate frequency converter, and the signal detector receives the voltage value of the signal applied from the second intermediate frequency converter. Detect and apply to the controller. The controller converts the phase of the signal through the phase shifter when it is determined that the oscillation phenomenon exists by comparing the voltage value applied from the signal detector. The phase shifter converts a phase of a signal applied from the second coupler through the first attenuator and the second attenuator to the first coupler by converting a phase to have a phase opposite to that of the echo signal under the control of the controller. Since the phase shift signal and the echo signal applied to the first coupler are opposite in phase to each other, the phase shift signal and the echo signal cancel each other and only the base station signal remains, so that the oscillation phenomenon due to the echo signal is eliminated.

Description

Method and apparatus for removing echo signal of RF repeater {Method and apparatus for removing a feedback signal of RF repeater}

The present invention relates to an RF repeater of a mobile communication network, and more particularly, to generate a signal generated by an echo signal of an RF repeater by controlling the signal output from an RF repeater that transmits a signal received from a base station to a mobile terminal. The present invention relates to a method and apparatus for preventing oscillation of an RF repeater capable of preventing oscillation.

In general, the RF repeater transmits a signal applied from the base station to the mobile terminal and simultaneously transmits a signal received from the mobile terminal to the base station. The RF repeater is provided with an antenna for a base station for transmitting and receiving a signal with a base station on one side, and an antenna for a mobile terminal for transmitting and receiving a signal with a mobile terminal on the other side of the RF repeater. The base station antenna and the mobile terminal antenna is to adjust the installation direction so as not to interfere with each other. The signal transmitted to the mobile terminal through the antenna for the mobile terminal of the RF repeater is echoed back to the antenna for the base station there is an echo signal received. On the contrary, the signal transmitted to the base station through the antenna for the base station is echoed back to receive the echo signal received by the antenna for the mobile terminal. If the magnitude of the echo signal is small, it does not affect the RF repeater. However, when the echo signal is large, there is a problem not only affecting the RF repeater but also affecting the base station.

In order to prevent the echo signal from having a predetermined value or more, the installation direction of the antenna for the base station and the antenna for the mobile terminal is adjusted so that the RF repeater has a constant isolation value. When the separation value between the antenna for the base station and the antenna for the mobile terminal gains more than a set value, the signal transmitted from the antenna for the mobile terminal is input to the antenna for the base station, and the output of the RF repeater is continuously increased. This affects the maximum amplification value (AMP) of the repeater, HPA or LPA, which in turn affects the base station.

For example, an RF repeater with a base station antenna and an antenna for a mobile terminal normally installed has a separation value of 90 dB, a received input received from the base station antenna of the RF repeater is -80 dBm, and the gain of the RF repeater is 80 dB. When the final output output through the antenna for 0dBm is set, the final output signal is again received through the antenna for the base station is -90dBm because the separation value is 90dB. The -90 dBm is combined with -80 dBm, which is a signal applied from the base station, and eventually -79.6 dBm obtained by -90 dBm + -80 dBm is applied to the RF repeater. The -79.6dBm is larger than the original signal -80dBm, but there is no significant difference, which causes slight variation in the RF repeater, but does not affect the system of the RF repeater.

However, if the installation direction of the base station antenna or mobile terminal antenna of the RF repeater is changed due to environmental factors or external shocks, the separation value of the RF repeater is changed, and when the changed separation value is 80 dB, the base station The signal reflected by the antenna is -80dBm, and the -80dBm is combined with the -80dBm signal received from the base station. As a result, -77 dBm obtained from -80 dBm + -80 dBm is applied to the RF repeater, and -77 dBm is a result of an increase of 3 dB from -80 dBm applied from the base station. As a result, the signal input to the RF repeater is continuously inputted with a signal increased by 3 dB, and thus an input signal much larger than the original received signal of -80 dB is applied.

Accordingly, the present invention has been made to solve the above problems, the first object of the present invention is to be echoed back after being output from the antenna for the mobile terminal of the RF repeater is received through the antenna for the base station is detected The present invention provides a method of removing an echo signal of an RF repeater capable of removing an echo signal by generating an inverted signal having a phase opposite to the echo signal.

In addition, a second object of the present invention is to provide an apparatus for removing the echo signal of the RF repeater suitable for performing the method for removing the echo signal of the RF repeater.

1 is a view schematically showing an apparatus for removing the echo signal of the RF repeater according to the present invention.

2 is a flowchart schematically illustrating a method of removing an echo signal of an RF repeater according to the present invention.

<Brief description of symbols for the main parts of the drawings>

10: base station 12: base station antenna

20: RF repeater 22: antenna for mobile terminal

24: first coupler 26: low noise amplifier

28: first local unit 30: first intermediate frequency conversion unit

32: second local unit 34: second intermediate frequency conversion unit

36: amplifier 38: power amplifier

39: second coupler 42: signal detection unit

44: control unit 46: memory unit

48: first attenuator 50: second attenuator

52: phase shift unit

In order to achieve the first object as described above, the present invention includes a first step of obtaining a amplitude value of a voltage from a graph of voltage vs. time of a detected signal by detecting a signal from a second intermediate frequency converter of an RF repeater; A second step of storing an amplitude value of the voltage sensed in the first step in a memory unit; A third step of determining whether the operation of storing the amplitude value in the memory unit has reached a set number (N) in the second step; A fourth step of repeating the first step if the number of times set in the third step is not repeated and calculating a difference between the maximum value and the minimum value from the amplitude values of the N voltages stored in the memory unit when the set number of times is reached; A fifth step of comparing the amplitude values of the voltages calculated in the fourth step with a reference value stored in a memory unit in a table; A sixth step in which the oscillation phenomenon is determined by comparing the amplitude value and the reference value in the fifth step; A seventh step of performing a first step if the oscillation phenomenon is not performed in the sixth step, and attenuating the magnitudes of the signals applied to the first attenuator and the second attenuator to the magnitude of the echo signal if the oscillation phenomenon; An eighth step of adjusting the phase of the signal applied from the second attenuator to the phase shifter after the seventh step so as to have a phase opposite to that of the echo signal; The eighth step is followed by a ninth step of applying a phase shift signal having a phase opposite to the echo signal to the first coupler.

In addition, to achieve the second object of the present invention, a base station signal is applied from the base station, the echo signal and the phase shift signal applied from the antenna for the mobile terminal is applied through the antenna for the base station and synthesized; A low noise amplifier for amplifying a signal applied from the first coupler; A first intermediate frequency converter converting a signal applied from the low noise amplifier into an intermediate frequency by a signal applied from a first local part; A second intermediate frequency converting unit converting the signal applied from the first intermediate frequency converting unit into an intermediate frequency according to the signal applied from the second local unit; An amplifier for amplifying a signal applied from the second intermediate frequency converter; A second coupler for outputting a signal applied from the amplifier through a power amplifier through an antenna for a mobile terminal; A first attenuator for attenuating the magnitude of the signal applied from the second coupler; A second attenuator for attenuating the magnitude of the signal applied from the first attenuator; A phase converting unit converting a phase of a signal applied from the second attenuator; A signal detector for detecting a signal from the second intermediate frequency converter; And a controller for analyzing a signal applied from the signal detector as a ratio of voltage to time and applying a signal to attenuate the magnitude of the signal to the first attenuator and the second attenuator and a phase shifter to convert a phase of the signal. Provided is an apparatus for removing the echo signal of the RF repeater consisting of.

According to the present invention, the base station signal, the echo signal, and the phase shift signal introduced into the repeater through the base station antenna are mixed in the first coupler and applied to the low noise amplifier. The low noise amplifier amplifies the signal and is applied to the signal coupler second coupler through the first intermediate frequency converter and the second intermediate frequency converter, and the signal detector receives the voltage value of the signal applied from the second intermediate frequency converter. Detect and apply to the controller. The controller converts the phase of the signal through the phase shifter when it is determined that the oscillation phenomenon exists by comparing the voltage value applied from the signal detector. The phase shifter converts a phase of a signal applied from the second coupler through the first attenuator and the second attenuator to the first coupler by converting a phase to have a phase opposite to that of the echo signal under the control of the controller. Since the phase shift signal and the echo signal applied to the first coupler are opposite in phase to each other, the phase shift signal and the echo signal cancel each other and only the base station signal remains, so that the oscillation phenomenon due to the echo signal is eliminated.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

1 is a view schematically showing a device for removing the echo signal of the RF repeater according to the present invention, Figure 2 is a flow chart schematically showing a method for removing the echo signal of the RF repeater according to the present invention.

Hereinafter, the present invention will be described with reference to FIGS. 1 and 2.

First, the base station signal A output from the base station 10, the echo signal B applied from the mobile terminal antenna 22 of the RF repeater 20, and the phase shift signal applied from the phase converter 52 (C) is applied to the first coupler 24 of the RF repeater 20 through the base station antenna 12. The first coupler 24 synthesizes the base station signal A, the echo signal B, and the phase shift signal C, and sends the synthesized signal to the low noise amplifier 26. The low noise amplifier 26 transmits the first coupler. The signal applied from 24 is amplified and applied to the first intermediate frequency converter 30. The first intermediate frequency converter 30 may convert an intermediate frequency signal obtained by synthesizing a signal applied from the first local unit 28 and a signal applied from the low noise amplifier 26 to the second intermediate frequency converter 34. To apply. The second intermediate frequency converter 34 synthesizes a signal of an intermediate frequency applied from the first intermediate frequency converter 30 with a signal applied from the second local unit 32 to produce a signal of a lower intermediate frequency. To the amplifier 36. The signal of the intermediate frequency output from the second intermediate frequency converter 34 is applied to the amplifier 36 and the signal detector 42 at the same time.

The signal applied to the amplifier 36 is amplified and applied to the second coupler 39 through the power amplifier 38. The second coupler 39 transmits a signal to the mobile terminal through the antenna 22 for the mobile terminal, and at the same time, the second coupler 39 phase shifts through the first attenuator 48 and the second attenuator 50. The signal is applied to the unit 52. A part of the signal transmitted from the antenna 22 for the mobile terminal is an echo signal applied to the first coupler 24 through the base station antenna 12 of the RF repeater 20.

The signal detector 42 detects a voltage value of a signal applied from the second intermediate frequency converter 34 and applies it to the controller 44. When the controller 44 compares and analyzes the signal applied from the signal detector 42 in the ratio of voltage to time, it can determine whether oscillation is occurring. When the oscillation occurs by analyzing the ratio of voltage vs. time of the signal applied from the signal detecting unit 42, the amplitude of the sine wave appearing in the graph of the voltage vs. time becomes large and there is almost no oscillation phenomenon. There is almost no amplitude.

The controller 44 stores the amplitude value obtained by comparing and analyzing the signals applied from the signal detector 42 in the memory unit 46, and the controller 44 oscillates from the amplitude value stored in the memory unit 46. It is possible to determine whether a phenomenon occurs, and at the same time, the controller 44 compares the amplitude value stored in the memory unit 46 with the reference value stored in the memory unit 46 to compare the antenna 22 for the mobile terminal. It is possible to know the intensity of the echo signal reflected from.

The controller 44 controls the first attenuator 48 and the second attenuator 50 to attenuate the magnitude of the signal applied from the second coupler 39 to the magnitude of the echo signal, and the second attenuator 50. The signal applied to the phase shifter 52 from the phase is inverted in phase by the control of the controller 44 and applied to the first coupler 24. The controller 44 controls the degree of phase shifting of the signal by the phase shifter 52 according to the strength of the echo signal obtained from the amplitude value stored in the memory 46.

The phase shift signal C applied from the phase shifter 52 to the first coupler 24 is the same magnitude as that of the echo signal B and is opposite in phase. The converted signal and the echo signal are lost and only the base station signal A remains. Therefore, the oscillation phenomenon due to the echo signal is eliminated.

Referring to the present invention through an embodiment, first, from the second intermediate frequency converter 34 of the RF repeater 20, the signal detector 42 detects a signal from a graph of voltage versus time of the detected signal. An amplitude value of the voltage is obtained (first step S100). The amplitude value of the voltage sensed in the first step S100 is stored in the memory unit 46 (second step S110). In the second step S110, it is determined whether the number of operations for storing the amplitude value in the memory unit 46 has been set (N) (third step S120). If the set number (N) has not been set in the third step (S120), the first step (S100) is repeatedly executed, and if the set number is reached, the difference between the maximum value and the minimum value from the amplitude values of the N voltages stored in the memory unit 46 is repeated. Calculate the fourth step (S130). The amplitude values of the voltages calculated in the fourth step S130 are tabulated and compared with the reference values stored in the memory unit 46 (step S140). In operation S140, the oscillation phenomenon may be determined by comparing the amplitude value with the reference value (operation S150). If the oscillation phenomenon is not performed in the sixth step S150, the first step S100 is executed. If the oscillation phenomenon occurs, the magnitude of the signal applied to the first attenuator 48 and the second attenuator 50 is the magnitude of the echo signal. Attenuation (seventh step S160). After the seventh step S160, the phase of the signal applied from the second attenuator 50 to the phase conversion unit 52 is adjusted to have a phase opposite to that of the echo signal (step S170). . After the eighth step S170, a phase shift signal having a phase opposite to that of the echo signal is applied to the first coupler 24 (ninth step S180).

As can be seen from the above description, in the present invention, the base station signal, the echo signal, and the phase shift signal introduced into the repeater through the base station antenna are mixed in the first coupler and applied to the low noise amplifier. The low noise amplifier amplifies the signal and is applied to the signal coupler second coupler through the first intermediate frequency converter and the second intermediate frequency converter, and the signal detector receives the voltage value of the signal applied from the second intermediate frequency converter. Detect and apply to the controller. The controller converts the phase of the signal through the phase shifter when it is determined that the oscillation phenomenon exists by comparing the voltage value applied from the signal detector. The phase shifter converts a phase of a signal applied from the second coupler through the first attenuator and the second attenuator to the first coupler by converting a phase to have a phase opposite to that of the echo signal under the control of the controller. Since the phase shift signal and the echo signal applied to the first coupler are opposite in phase to each other, the phase shift signal and the echo signal cancel each other and only the base station signal remains, so that the oscillation phenomenon due to the echo signal is eliminated.

Claims (3)

delete A first coupler which is synthesized by applying a base station signal applied from the base station, an echo signal applied from the antenna for the mobile terminal, and a phase shift signal through the base station antenna; A low noise amplifier for amplifying a signal applied from the first coupler; A first intermediate frequency converter converting a signal applied from the low noise amplifier into an intermediate frequency by a signal applied from a first local part; A second intermediate frequency converting unit converting the signal applied from the first intermediate frequency converting unit into an intermediate frequency according to the signal applied from the second local unit; An amplifier for amplifying a signal applied from the second intermediate frequency converter; A second coupler for outputting a signal applied from the amplifier through a power amplifier through an antenna for a mobile terminal; A first attenuator for attenuating the magnitude of the signal applied from the second coupler; A second attenuator for attenuating the magnitude of the signal applied from the first attenuator; A phase converting unit converting a phase of a signal applied from the second attenuator; A signal detector for detecting a signal from the second intermediate frequency converter; And a controller for analyzing a signal applied from the signal detector as a ratio of voltage to time and applying a signal to attenuate the magnitude of the signal to the first attenuator and the second attenuator and a phase shifter to convert a phase of the signal. Apparatus for removing the echo signal of the RF repeater. The magnitude of the echo signal according to claim 2, wherein the controller analyzes a signal applied from the signal detector as a ratio of voltage to time, calculates an amplitude value of the voltage, and compares the magnitude of the echo signal with a table value stored in the memory unit. And an echo signal of the RF repeater, characterized in that the phase is measured.