KR101060585B1 - Wireless repeater with echo canceller and echo signal cancellation method - Google Patents

Abstract

According to the present invention, a signal transmitted through a transmitting antenna of a wireless repeater used for expansion of a service area or improvement of quality in wireless communication or broadcasting communication such as broadcasting, fixed wireless communication, as well as cellular mobile communication, is received as a receiving antenna. The present invention relates to an apparatus for improving an echo signal canceling method in a wireless repeater including an echo canceller that can effectively cancel a re-input echo signal.

In the present invention, by using a complex correlation between an input signal input to a wireless repeater and a predetermined internal reference signal to remove the echo signal, the echo signal component included in the input signal is restored and removed from the input signal, thereby achieving higher quality. To provide communication services.

Description

Wireless repeater with echo cancellation device and echo cancellation method {ECHO CANCELLATION METHOD AND WIRELESS REPEATER WITH ECHO CANCELLER UNIT}

1 to 8 illustrate embodiments of the present invention related to a wireless repeater including an echo cancellation device.

1 is a block diagram illustrating an embodiment of a wireless repeater including an echo cancellation device.

FIG. 2 is a detailed block diagram illustrating an embodiment of the echo cancellation device shown in FIG. 1.

3 is a block diagram showing the internal structure of the ECU finger in the echo cancellation device shown in FIG.

4 is a flowchart illustrating a process of removing and transmitting an echo signal from a received signal.

FIG. 5 is a flowchart illustrating a process of receiving and converting a signal in the flowchart of FIG. 4.

FIG. 6 is a flowchart illustrating a process of removing an echo signal from the flowchart of FIG. 4.

FIG. 7 is a flowchart illustrating a process of generating an echo reconstruction signal in the flowchart of FIG. 6.                 

8 is a flowchart illustrating a process of converting and transmitting a signal from which an echo signal is removed from the flowchart of FIG. 4.

The present invention relates to a mobile repeater system as well as a wireless repeater used in broadcasting, fixed wireless, and various other wireless or broadcast communications, and particularly, a signal transmitted through a transmitting antenna of a wireless repeater is received. The present invention relates to a wireless repeater including an echo canceller unit for adaptively canceling an echo signal re-input to an antenna according to a change of an echo signal and a method of implementing the same.

For example, a mobile communication system can be broadly classified into a mobile switch, a base station (BS), and a mobile terminal.

The mobile communication exchange handles calls and calls from each base station through connection with each base station controller (BSC) and provides a public telephone network (PSTN) with a central control function to ensure that all base stations operate efficiently. It plays a role of making connection with other networks such as Public Switch Telecommunication Network).

A base station (BS) connects a mobile terminal and a mobile communication switch to perform a function of allowing a user to talk with a desired counterpart. The base station (BS) includes a base station controller (BSC), a base station transceiver subsystem (BTS) and a repeater. . Repeaters are used to expand cell coverage of base stations and are classified into optical repeaters, wireless repeaters, and laser repeaters according to the type of transmission medium. The wireless repeater performs a function of receiving, amplifying and transmitting a weakened radio signal transmitted over the air from the base station to the mobile terminal or from the mobile terminal to the base station.

Such a wireless repeater generally includes two antennas, a link antenna and a service antenna, and amplifies a base station forward link signal received through the link antenna to surround the antenna through a service antenna. And amplifies a reverse link signal of the mobile terminal received through the service antenna and transmits it to the base station through the link antenna. Thus, each antenna performs both transmission and reception functions through one antenna.

At this time, since the frequencies of the radio signals transmitted and received are the same, some of the signals output through the transmitter are directly or reflected through the space and are input in the form of echo signals through the receiver. do. The echo signal is combined with the original signal received from the base station or the mobile terminal, amplified and output again through the transmitter. If such processes are repeated, the wireless repeater generates oscillation. In addition, the specific gravity of the echo signal is gradually increased than that of the original signal, so that the characteristics of the signal received at the mobile terminal, in particular, are remarkably inferior.

As another example, in the case of a satellite multimedia broadcasting system, since a frequency of a broadcast signal transmitted by a wireless repeater and a broadcast signal transmitted from a satellite through a gap filler from a satellite is equal, some of the signals output through the transmitter are transmitted through a space. Occurs when it is directly or reflected is input through the receiving device in the form of an echo signal. The echo signal is combined with the original signal received from the gap filler, amplified and output again through the transmitter. When such processes are repeated, the wireless repeater generates oscillation. In addition, the weight of the echo signal is gradually increased than that of the original signal, and thus, in particular, the characteristics of the signal received at the receiver side of the user are significantly reduced.

In order to prevent the problem caused by the echo signal, the distance between the transmitter and the receiver of the wireless repeater is sufficiently secured to increase the signal isolation between the transmitter and the receiver, thereby increasing the level of the echo signal. It should be small enough to be negligible than the original signal is input through. However, in reality, they are less efficient in terms of cost, space and maintenance.

Therefore, a separate echo cancellation apparatus capable of removing such an echo signal is required. In the related art, a method of eliminating echo signals by frequency allocation (FA) has been mainly used. In other words, the echo signal is removed by despreading the CDMA signal, which requires all the echo cancellation apparatuses for each frequency band, which complicates the construction of the repeater.

The present invention is to provide a wireless repeater and echo cancellation method including an echo cancellation device that can remove the echo signal component by separating the original signal and the echo signal from the signal input through the antenna of the wireless repeater to solve the above problems do. In addition, the present invention can be applied to all signals having complex correlation characteristics. The present invention is applicable to the case of removing the echo signal for each FA, as well as to provide an echo canceling apparatus and method that can be applied as one algorithm regardless of the frequency band.

The description herein focuses on a wireless repeater used in a cellular mobile communication system, but the present invention is not limited thereto, and the present invention also applies to a wireless repeater for general wireless broadcasting or broadcasting.

The wireless repeater including the echo canceller measures the amplitude, phase, and delay time of the echo signal through a complex correlation between an externally received input signal containing echo signal components and a reference signal generated from the final output of the echo canceller. By estimating, an echo reconstruction signal is generated that matches the echo signal component, thereby removing the echo signal component from the input signal. To this end, the wireless repeater of the present invention includes an echo cancellation device that can remove an echo signal component by dividing an original signal and an echo signal from an input signal using a complex correlation.

1 is a block diagram illustrating an embodiment of a wireless repeater including an echo cancellation device. As shown in FIG. 1, the wireless repeater branches the transmitting end and the receiving end to transmit and receive signals through the link antenna 100 and the link antenna 100 for signal transmission and reception with a signal transmitting station such as a base station or a gap filler. The first and second duplexers 101, a mobile terminal or a WLL terminal or a wireless LAN reception modem, such as a service antenna 120 and a service antenna 120 for transmitting and receiving a signal with a user antenna 120 The second duplexer 115 for branching the transmitting end and the receiving end so as to enable both, and the forward link 103 and the service antenna 120 for processing the signal received through the link antenna 100 to output to the service antenna 120 It includes a reverse link 123 for processing the signal received through the output to the link antenna 100. When there is no reverse link, such as a broadcast wireless repeater, it has only the elements in the range necessary to process the forward link. For example, it uses only a unidirectional filter instead of a bidirectional filter such as a duplexer, and does not have a reverse link. It only performs the function of receiving and does not transmit a signal to the sending side. Although the following description mainly focuses on a cellular mobile communication system, this is generally applied to a wireless communication system, and it is obvious that a reverse link may be omitted in a broadcasting system.

Forward link 103 and reverse link 123 are low noise amplifiers (102, 122, LNA: Low Noise Amplifier), frequency down converters (104, 124, DNC), analog / digital converters (106, 126, ADC / Analog / Digital Converter) , Echo canceller (108, 128, echo canceller unit), digital / analog converter (110,130, digital / analog converter), frequency upconverter (112,132, up converter) and linear power amplifier (114,134, lpa: Linear Power Amplifiers).

In the above configuration, the frequency downconverter and the frequency upconverter are selectively required in case of performing echo cancellation by converting a band of a received RF signal and not in case of performing echo cancellation without converting a band of a received signal. In general, when the frequency band of the received signal is close to 1Ghz, it is more suitable to convert the signal into a low band signal and process the received signal as it is. It is a matter of choice to consider to be optimized.

The signal received through the link antenna 100 of the wireless repeater is input to the low noise amplifier 102 through the first duplexer 101. At this time, the signal received through the link antenna 100 is an analog signal of a radio frequency band (Radio Frequency Band) is a signal in which the original signal from the base station and the echo signal components of the previously output signal are combined. In the low noise amplifier 102, the noise of the input signal is minimized and amplified, and the signal amplified by the low noise amplifier 102 is an intermediate frequency in the signal of the radio frequency band RF Ban (1) through the frequency down converter 104. The signal is converted into a signal of an intermediate frequency band, and the analog signal of the IF band is converted into a digital signal through the analog-to-digital converter 106 and input to the echo canceller 108. The conversion to the IF signal may sometimes be omitted.In the present specification, the IF signal is defined as a baseband signal as well as a signal converted to a band located between the signal of the received band and the baseband signal. In addition, the conversion may be performed at one time or may be performed in two or more stages .. In the echo cancellation apparatus 108, complex correlation is performed. It removes the echo signal component from the input signal and outputs only the original signal to be transmitted, which is converted into an analog signal of RF band through the reverse signal conversion process and sent to the mobile terminal. To analog signal through analog converter 110, to RF band via frequency upconverter 112, and then amplified by linear power amplifier 114 to second duplexer 115. Is transmitted to the mobile terminal through the service antenna 120. In this process, the intermediate frequency band is the same as defined in the above-described receiver, and is omitted when the frequency conversion is omitted by the receiver. The signal received through) is also sent to the base station through the same process.

FIG. 2 is a block diagram illustrating an embodiment of an echo canceling device of FIG. 1.

The echo canceling devices 108 and 128 of FIG. 2 have the same structure and operation characteristics in both the forward link 103 and the reverse link 123, and thus will not be described separately.

As shown in FIG. 2, the echo canceling device includes an echo signal detector 202 (ECU Searcher), a plurality of fingers (hereinafter referred to as ECU fingers) 210-1, 210-2 ..., 210-N and an operator 206. ). In order to improve the performance of the echo canceller and to improve the operation efficiency, the automatic level controller 208 (ALC: Automatic Level Controller), the automatic gain controller 1 (204, AGC: Automatic Gain Controller), and the automatic gain controller 2 (209) are optional. And one or more of an AGC (Automatic Gain Controller), a Band Pass Filter (210) and a Group Delay Equalizer (211). In FIG. 2, the signal S _I (t) input to the echo canceller is a digital signal of an intermediate frequency IF band, and the output signal S _{O is applied} to the original signal S (t) to be amplified. (t)) is a signal to which the echo signal S _E (t), which is re-input in a delayed form through several paths, is added. When the conversion to the intermediate frequency signal is omitted, an echo cancellation method may be applied to the baseband signal. The input signal may be represented in the form of an input signal S _I (t) = original signal S (t) + echo signal S _E (t), which can be expressed as Equation 1 below. have.

However, K _i , P _i , and T _i represent the amplitude, phase, and delay time of the output signal obtained by the i-th path, respectively, compared to the control time of the echo canceller. The echo canceller operates at a speed that can be assumed to be constant.

Referring to FIG. 2, the echo canceling device is configured in the form of a circulating loop, and input signal S _I (t) and a predetermined reference signal S _Ref (t) input in the form of Equation (1). By using to generate the echo recovery signal (S ＾ _E (t)) the same as the components of the echo signal (S _E (t)) included in the input signal (S _I (t)), the input signal (S _I The echo signal S _E (t) is removed and output from (t)). In other words, the echo signal detector 202 uses the input signal S _I (t) and the reference signal S _Ref (t) to reflect the echo signal S _E (included in the input signal S _I (t)). Detect the delay time of t)) and assign the corresponding ECU finger. Each ECU finger assigned by the echo signal detector 202 as a finger to remove the echo signal S _E (t) uses an input signal S _I (t) and a reference signal S _Ref (t). By estimating the amplitude (K), phase (P), and delay time (T) of the echo signal (S _E (t)), the respective echo reconstruction signals (S ＾ _E1 (t), S) corresponding to the corresponding echo signal components are estimated. ＾ _E2 (t) ..., S ＾ _EN (t)) and subtracted from the input signal S _I (t) using the calculator 206 to produce the echo signal component S _E (t). Remove it. This can be expressed as [Equation 2].

2 and [Equation 1], the function of each hardware block of the echo canceller will be described in more detail.

Automatic level controller 208 but the power of the signal (S _O (t)) to be input to them through the signal when below a certain level as it is, if the predetermined level or more, and outputs the attenuated signal. This prevents the system from oscillating when a new echo signal is input due to the initial state of the system or a sudden change of environment, and the echo cancellation function does not operate normally. The automatic level controller can optionally be applied as a complementary component to prevent oscillation. In addition, when the system gain is excessively increased, the automatic level controller controls the input level of the input signal to a predetermined level or less until the echo signal detector and the finger return to normal operation. The functions of the automatic level controller are not essential as elements for improving the functions of the echo control device and the wireless repeater, but may be selectively applied.

The automatic gain controller 1 204 adjusts the gain for the input signal _SO (t) so that the output power always maintains a constant range of values or a constant value, and adjusts the gain to the system input signal S _I (t). a reference signal (S _Ref (t)) to find the components of the echo signal including removal and generates from the output signal (S _O (t)). The function of the automatic gain controller 1 is not essential as an element for improving the function of the echo control device, but may be selectively applied.

The automatic gain controller 2 (209) defades the rapidly changing input signal (I / Q) in a fading environment so that the output power always maintains a constant range or constant value for input to the echo signal detector and the calculator. To adjust the gain. In the actual propagation environment, due to various causes, the power level and the phase of the input signal are suddenly changed, and the fading phenomenon is particularly severe. Because of this, the echo cancellation algorithm responds quickly because an error occurs due to the time difference between the detection of the reflected wave and the step of removing the reflected wave. Therefore, it is useful to control the input of the echo canceller in advance to maintain it within a predetermined reference value or reference range. . The automatic gain controller may be used as it is, or modified as it is usually used in mobile communication base stations or other repeaters, or may be newly designed and added in the same principle. The function of the automatic gain controller 2 is not essential as an element for improving the function of the echo control device, but may be selectively applied.

The band pass filter 210 mainly uses the non-linearity of the automatic level controller 208 and removes signals outside the pass band due to noise or other factors and inputs them to the automatic gain controller 1 and the transmitting device. The signal input to the echo canceller in the wireless repeater may include a band which is not actually provided or used for service. For example, the service frequency authorized by the operator is 20Mhz, but if only 1FA or 2FA is provided to the service depending on the actual call volume in the area where the wireless repeater is installed, the band provided to the service may be only a few Mhz. In this case, if only the signal of the number of Mhz is input to the echo canceller without inputting the signal of the entire 20 Mhz band, the signal-to-noise ratio can be improved to obtain higher echo cancellation performance. Therefore, it is preferable to set a pass band to a band occupied by a channel used for control, communication, or data signals. The function of the band pass filter is not essential as an element for improving the function of the echo control device, but may be selectively applied.

The group delay equalizer 211 corrects a time error for each frequency of the radio signal. Even when the electromagnetic signal is transmitted through the same path, a time error may occur depending on the frequency band due to various factors in the signal path including characteristics of the filter, which may cause errors in the operation of the delay equalizer. The group delay equalizer may be used as is or modified in the existing communication system such as satellite communication, or may be newly designed and added in the same principle. The value to be calibrated also depends on the nature of the signal path. The function of the group delay equalizer is not essential as an element for improving the function of the echo control device, but may be selectively applied. The group delay equalizer is preferably located at the output of the echo canceller as shown in FIG. 2, but may be located before and after the automatic gain controller 2 of the input.

The echo signal detector 202 functions to find the delay time of the echo signal components S _E (t) included in the system input signal S _I (t), and these echo signals S _E (t). The number of echo signal components to be removed (N) and the delay time (Ti) are identified and the corresponding ECU fingers are allocated.

The ECU fingers 210-1, 210-2, ... 210-N serve to restore the echo signal S ＾ _Ek (t) of the specific delay time region allocated by the ECU detector 202, and In other words, the allocation is variably assigned by the ECU detector 202 within a number provided by hardware. In addition, each ECU finger can perform the echo cancellation state through an internal adaptive algorithm using complex correlation of the signal even when the amplitude, phase, and delay time of the currently assigned echo signal component change due to external environmental changes. Has the ability to keep at maximum.

3 is a block diagram illustrating an internal structure of a kth ECU finger among the ECU fingers shown in FIG. 2.

In the present invention, the echo signal cancellation function is mostly performed by each ECU finger shown in FIG. As mentioned above, the ECU finger generates an echo recovery signal using the relationship between the input signal and a predetermined reference signal. The reference signal S _Ref (t), which is an output of the automatic gain controller 204, is a signal obtained by multiplying the system output signal by the gain of the automatic gain controller 204, and may be expressed as in Equation 3 below.

The reference signal as shown in Equation 3 is a phase (P ＾ _k ) and a delay time specified by the ECU algorithm through the delay equalizer 302 and the phase equalizer 304 shown in FIG. 3. By (T ＾ _k ) is changed, can be expressed as shown in Equation 4 below. When the automatic gain controller 1 204 is not used, the reference signal S _Ref (t) will use the output signal S _O (t) as it is.

The complex correlator 308 calculates a complex correlation between the input signal S _I (t) and the reference signal S ＾ _ref (t) shown in Equation 4, The final echo reconstruction signal S ＾ _Ek (t) is generated for the k th echo signal S _Ek (t) expressed as follows.

On the other hand, control of the equalizers 302, 304, and 306 in the ECU finger is controlled by using the complex correlator 308, as shown in FIG. 3, with the input signal S _I (t) and the reference signal S ＾ _ref. (t)). At this time, the complex correlation function of the two signals can be expressed by Equation 6 below using Equation 1.

_{Here, R (T ^ k - T} i) is the autocorrelation function (Autocorrelation function) of the output signal (S _O (t)) has a real number value (Real Number). In addition, when one or several signals are combined in the same signal band, the autocorrelation function R (τ) has a maximum value when τ = 0, and converges to zero as the absolute value of τ increases.

Using this characteristic, the k th echo signal component S _Ek (t) in which the initial value T ＾ _k of the delay equalizer 302 by the ECU detector 202 is included in the input signal S _I (t). If it is determined as the value Tk near the delay time of)), the complex correlation function value of Equation 6 can be expressed as Equation 7 below.

On the other hand, since the power P _Ref of the reference signal S _Ref (t) is always maintained at the same value by the automatic gain controller 204, it can be expressed as Equation (8).

Using the results of Equations 7 and 8, the complex correlation function can be expressed as Equation 9 below.

Each equalizer in the ECU finger uses the result of Equation 9 to generate a signal S ＾ _Ek (t) that restores the k th echo component. In other words, the delay equalizer 302 is a reference signal (S _Ref (t)) delay (T ^ _k) k delay of the second echo signal component values of the input signal (S _I (t)) (T _k) and the Keeps the same This uses the characteristic that the autocorrelation function R (τ) has a maximum value at τ = 0. In addition, the phase equalizer 304 is equal to the reference signal (S _Ref (t)) phase (P ^ _k), the input signal (S _I (t)) phase (P _k) of the k-th echo signal component of the Make it. To do this, the reference signal such that the complex correlation function value C (T ＾ _k , P ＾ _k ) is always a real number so that the phase component ((P ＾ _k -P ＾ _k )) in Equation 9 can be zero. thereby changing the phase of the (S _Ref (t)). Finally, the amplitude equalizer 306 can obtain an amplitude correction value in the complex correlation function comprising a delay and phase correction. When the phase and delay compensation performed, [ The complex correlation function of Equation 9 can be expressed as Equation 10 below.

는 정해져 있거나, 측정할 수 있으므로 k 번째 반향 신호의 진폭 보정값(K＾_k)은 아래 [수학식11]과 같이 설정할 수 있다.here,

Since is determined or can be measured, the amplitude correction value K ＾ _k of the k th echo signal can be set as shown in Equation 11 below.

4 to 8 are flowcharts illustrating a method of removing echo signal components from a signal input from a wireless repeater of the present invention including the echo canceller as described above.                     

Hereinafter, a method of removing echo signal components in the present invention will be described with reference to FIGS. 4 to 8.

Referring to FIG. 4, a method of removing an echo signal may include a first step S402 of receiving and converting a radio signal from an outside, and a signal S _I (t) that is converted and input to the echo canceller 108 or 128. A second step S404 and a second step (S404) of generating the signal S ＾ _E (t) from which the echo signal component S _E (t) is restored and removing it from the input signal S _I (t) Re-converting and transmitting the signal _SO (t) from which the echo signal is removed by S404 (S406). At this time, the radio signal received in the first step is an analog signal of the radio frequency band including the noise component and the echo signal component, as mentioned above.

FIG. 5 is a flowchart illustrating a process of converting a signal received in the first step S402 shown in FIG. 4. Referring to FIG. 5, the first step S402 includes receiving a wireless signal from the outside (S502), low noise amplifying the received wireless signal (S504), and converting a signal of a radio frequency band into a signal of an intermediate frequency band. Down conversion (S506) and converting an analog signal into a digital signal (S508).

FIG. 6 is a flowchart illustrating a process of removing echo signal components from an input signal in a second step S404 shown in FIG. 4. Referring to FIG. 6, the second step S404 is a delay time of the echo signal component S _E (t) included in the input signal S _I (t) converted and input by the first step S402. Detecting a value and assigning a corresponding echo cancellation finger (S602) and an echo signal component corresponding to a specific delay time from the input signal S _I (t) in each of the assigned echo cancellation fingers and S _Ek (t) ) Generating a matching echo recovery signal S ＾ _Ek (t) (S 604) and using the operator 206 and the echo recovery signal S ＾ _Ek (t) from the input signal S _I (t) In operation S606, the echo reconstruction signal S ＾ _Ek (t) included in the input signal S _I (t) is removed by subtracting. At this time, the operator 206 subtracts the reconstructed echo reconstruction signals from the reverberation cancellation fingers 210-1, 210-2, ... 210-N from the input signal S _I (t), as shown in FIG. Perform the operation.

FIG. 7 is a flowchart illustrating an operation of generating an echo reconstruction signal in step S604 of FIG. 6. As shown in FIG. 7, the method of generating the echo reconstruction signal S ＾ _Ek (t) is changed by changing the reference signal S _Ref (t) by a predetermined delay and a phase value so that the second reference signal S ＾ _ref ( t)) and using a complex correlation between the input signal S _I (t) and the second reference signal S ＾ _ref (t) and the predetermined delay value T ＾ _k . In step S704 of generating the phase value _Pfk and the amplitude correction value K ＾ _k and the reference signal S _Ref (t), the predetermined delay value T ＾ _k and the phase generated in step S704 are phased. A step S706 is generated by applying the value P ＾ _k and the amplitude correction value K ＾ _k to generate the echo restoration signal S ＾ _Ek (t).

On the other hand, the signal output from the echo cancellation device 108 or 128 through the second step is a digital signal of the intermediate frequency band. This signal is converted through the third step shown in FIG. 4 and transmitted to the outside.

8 is a flowchart illustrating a process of converting and transmitting a signal from which an echo signal component is removed in a third step. Referring to FIG. 8, the third step may include a digital / analog conversion step (S802) of converting a digital signal into an analog signal, a frequency upconversion step (S804) of converting a signal of an intermediate frequency band into a signal of a radio frequency band, and An amplification step (S806) of amplifying the power to a sufficient magnitude so that it can be sent to the outside and a transmitting step (S808) of transmitting the converted signal to the outside.

Through the above-described apparatus and method, echo restoration signals S ＾ _E1 (t), S ＾ _E2 (t) ..., S ＾ _EN (t) can be generated at each ECU finger, and echo cancellation is performed. By performing an operation as shown in Equation 2 using the operator 206 in the device 108, the echo signal component S _E (t) included in the input signal S _I (t) can be removed. have.

Such an echo cancellation device of the present invention can be applied to one algorithm irrespective of the FA (Frequency Allocation) number. The present invention can be applied not only to CDMA signals but also to all signals having the correlation characteristics described in the present invention. In particular, the echo canceller of the present invention, even in the case of cdma2000, WCDMA, orthogonal frequency division multiplexing (OFDM) -terrestrial DMB, Additive White Gaussian Noise (AWGN) signals, as well as combinations of these signals Can be used more effectively. Although it works more effectively when the control signal, call signal and data signal are used with certainty, it can be applied to all signals having correlation characteristics such as GSM, AMPS, etc.

In the above, the configuration and operation of the wireless repeater including the echo canceller according to the present invention has been described with reference to the above description and drawings, but this is merely exemplary and various applications and modifications within the scope without departing from the technical spirit of the present invention. This is possible.

According to the present invention, the wireless repeater whose function is improved in the function of the echo canceling device effectively removes the echo signal re-inputted through the receiving antenna by the signal transmitted through the transmitting antenna, thereby preventing oscillation of the wireless repeater, Provide communication services. In addition, the wireless repeater of the present invention may cancel the echo signal regardless of the number of assigned frequencies, the number of users, or the characteristics of the input signal.

Claims (27)

In a wireless repeater for communication or broadcasting, The wireless repeater receives a wireless signal from the outside; An echo canceller for detecting an echo signal included in the input signal by using a complex correlation between an input signal received by the receiver and a predetermined reference signal, and removing and outputting the echo signal from the input signal; And And a transmitter for transmitting a signal from which an echo signal component has been removed by the echo canceller to the outside. The echo canceller may include an echo signal detector configured to detect a delay time of echo signal components included in the input signal; One or more echo cancellation fingers for adaptively reconstructing the echo signal component of a particular delay time assigned by the always echo signal detector using the reference signal; And And an operator for performing a predetermined operation in response to the input signal and the signal from the echo cancellation fingers. delete The method of claim 1, The receiving device includes a receiving antenna for receiving an analog radio signal in a radio frequency band from the outside; A low noise amplifier for low noise amplifying the wireless signal; A frequency down converter for converting a signal in a radio frequency band from the low noise amplifier into a signal in an intermediate frequency band; And And an analog / digital converter for converting the analog signal from the frequency down converter into a digital signal. The method of claim 1, The transmitter comprises a digital to analog converter for converting a digital signal from the echo canceller into an analog signal; A frequency up converter for converting a signal of an intermediate frequency band input from the digital / analog converter into a signal of a radio frequency band; A linear power amplifier for amplifying and outputting a signal input from the frequency up-converter; And And a transmission antenna for transmitting the amplified signal to the outside. delete The method of claim 1, The echo cancellation device And an automatic gain controller 1 for adjusting a gain of a signal input from the calculator and generating the reference signal and inputting the echo signal detector and the echo canceling fingers. The method of claim 6, The echo cancellation device, And an automatic gain controller (2) which adjusts the power level of the signals inputted from the receiver to the echo signal detector and the calculator within a predetermined range. The method of claim 7, wherein The echo cancellation device, And an automatic level controller for attenuating the signal when the power level of the signal output from the calculator is greater than or equal to a predetermined level, controlling the signal to a predetermined level or less, and outputting the signal to the echo signal detector and the transmitter. The method of claim 8, The echo cancellation device And a band pass filter for filtering the input signal and outputting the filtered signal to the echo signal detecting device and the transmitting device to remove a signal of a band not provided to the service from the signal output from the calculator. Wireless repeater. The method of claim 9, The echo cancellation device And a group delay equalizer for compensating time delay deviations for each frequency of a signal input from the receiver to the echo signal detector and the calculator or a signal input from the calculator to the transmitter. Wireless repeater characterized. The method according to claim 6 or 7 or 8 or 9 or 10, And the echo reconstruction signal restored by the echo cancellation fingers coincides with a component of the echo signal included in the input signal. The method according to claim 6 or 7 or 8 or 9 or 10, And the calculator performs an operation of subtracting the echo recovery signals from the input signal. The method according to claim 6 or 7 or 8 or 9 or 10, The echo cancellation fingers may include a delay equalizer for changing a delay value of the reference signal; A phase equalizer for changing a phase value of a signal from the reference equalizer; A complex correlator for calculating a complex correlation between the input signal and the signal input from the phase equalizer to generate a predetermined delay correction value, a phase correction value, and an amplitude correction value; And And an amplitude equalizer for changing an amplitude of a signal input from the phase equalizer in accordance with the amplitude correction value. The method of claim 13, And the delay equalizer changes a delay value of the reference signal according to a delay correction value from the complex correlator. The method of claim 13, And the phase equalizer changes the phase value of the signal from the delay equalizer in accordance with the phase correction value from the complex correlator. In a wireless repeater for communication or broadcasting, An echo signal detector for detecting a delay time of echo signal components included in the input signal; One or more echo cancellation fingers for adaptively restoring a echo signal component of a particular delay time assigned by the echo signal detector using a predetermined reference signal; And And an operator for performing a predetermined operation in response to the input signal and the signal from the echo cancellation fingers. The method of claim 16, The echo cancellation device And an automatic gain controller 1 for adjusting a gain of a signal input from the calculator and generating the reference signal and inputting the echo signal detector and the echo canceling fingers. The method of claim 17, The echo cancellation device, And an automatic gain controller (2) for adjusting a power level of a signal input to the echo signal detector and the calculator from a receiving device that receives a radio signal from an external device within a predetermined range. The method of claim 18, The echo cancellation device, When the power level of the signal output from the calculator is more than a predetermined level attenuates the signal to control the predetermined level or less further comprises an automatic level controller for outputting to the echo signal detection device, the echo cancellation fingers and the transmitter Echo cancellation device characterized in that. The method of claim 19, The echo cancellation device A band pass filter for filtering an input signal to remove a signal of a band not provided to the service from the signal output from the calculator and outputting the signal to the echo signal detecting device, the echo canceling fingers, and the transmitting device. Echo cancellation device comprising a. The method of claim 20, The echo cancellation device A group delay equalizer for compensating and outputting a time delay deviation for each frequency group by receiving a signal input to the echo signal detector and the calculator or a signal input from the calculator to the transmitter. Echo cancellation device, characterized in that it further comprises. In the method for removing the echo signal from the signal received by the wireless repeater, A first step of receiving and converting a predetermined wireless signal from the outside and inputting the received signal to an echo cancellation device; A second step of removing an echo signal component included in the input signal input in the first step; And And transmitting a signal from which the echo signal component generated in the second step is removed to the outside. The second step is Detecting a delay time value of an echo signal component from the input signal and assigning corresponding echo cancellation fingers; Generating an echo reconstruction signal corresponding to a specific delay time matching an echo signal component from an input signal and a predetermined reference signal at each assigned echo cancellation finger; and Subtracting the echo reconstruction signal from the input signal. delete 23. The method of claim 22, When the power level of the signal output from the calculator that performs a predetermined operation in response to the signal from the input signal and the echo cancellation fingers is above a predetermined level, the signal is attenuated and controlled to be below a predetermined level to generate a reference signal. Echo signal cancellation method further comprising the step of. The method of claim 24, And filtering the input signal to generate the reference signal to remove a signal of a band not provided to the service from the signal output from the calculator. The method according to claim 22 or 24 or 25, The method further includes correcting a time delay deviation for each frequency group of the signal from which the echo reconstruction signal is subtracted from the input signal. The method according to claim 22 or 24 or 25, Generating the echo recovery signal Generating a second reference signal by changing a delay value and a phase value of the reference signal; Generating a delay value, a phase value, and an amplitude correction value for an echo signal included in an input signal using a complex correlation between the input signal and the second reference signal; And And generating an echo restoration signal by applying the corrected delay value, phase value, and amplitude correction value to the reference signal.

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