KR101045788B1 - ICS wireless repeater and its wireless relay method - Google Patents

Abstract

An interference cancellation system (ICS) wireless repeater and a wireless relay method thereof are disclosed. The wireless repeater of the present invention can remove the noise component around the service FA generated during the ICS operation by detecting the service FA being serviced in the region and setting the coefficient of the bandpass FIR filter optimized for the detected service FA. have. Accordingly, the administrator can easily install the wireless repeater even without a separate setting action according to the surrounding wireless situation.

Wireless Repeater, ICS, Service FA Detection, Power Measurement, FIR Filter

Description

ICS wireless repeater and wireless repeating method thereof

According to the present invention, a FA installed in a CDMA or WCDMA-based mobile communication network is detected and a filter coefficient is set based on the detection result. The present invention relates to an ICS wireless repeater capable of removing noise and a wireless relay method thereof.

Wireless communication protocols known to date are allocated a predetermined frequency band, and divided into a plurality of frequency assignment frequency (FA) frequencies and used as multiple channels. For example, in the case of Code Division Multiplex Access (CDMA), the frequency bandwidth of one FA is 1.23 MHz, and the frequency bandwidth of one FA is 5 MHz according to WCDMA regulations.

On the other hand, the signal transmission between the base station and the mobile terminal belonging to the wireless mobile communication network system is limited due to various obstacles in the air (Air). The device used to overcome this limitation is a wireless repeater.

The wireless repeater is used to solve the shadow area that does not receive a good communication service by amplifying and retransmitting a weak signal transmitted from at least one base station to the service area. One of the important problems of the wireless repeater is the processing of the interference signal which feedback oscillates between antennas. Various interference cancellation system (ICS) algorithms for removing such interference signals have been proposed, and a wireless repeater having an ICS function is called an ICS repeater.

In addition, since noise is generated around the service FA by the ICS operation, the ICS repeater must include a filter for removing noise from the signal after the ICS operation. Therefore, the ICS repeater needs a technique for distinguishing and detecting service FAs and controlling filter coefficients according to the detected service FAs.

An object of the present invention is to provide a service FA according to an ICS (Interference Cancellation System) operation by detecting a FA installed in a CDMA or WCDMA based mobile communication network and setting a filter coefficient based on the detection result. An object of the present invention is to provide an ICS wireless repeater capable of removing ambient noise and a wireless relay method thereof.

In order to achieve the above object, according to the present invention, in order to relay the radio signal according to the CDMA or WCDMA regulations, performing an ICS (Interference Cancellation System) operation on the received radio signal and outputting again as a radio signal The wireless relay method may further include calculating FA-channel power, which is power of a radio signal of each FA frequency band, and out-of-service power, which is power of a band in which a wireless relay service is not provided; Determining, as a service FA, an FA having a channel-specific power for each FA whose difference with the out-of-service power is greater than a reference value among channel-specific powers for each FA; And setting a coefficient of a band pass filter that operates after the ICS operation based on the determined service FA to remove noise according to the ICS operation.

According to an embodiment, the wireless relay method may include: calculating total power of a band that is power of a whole band available for wireless relay service; And when the value obtained by subtracting the out-of-service power from the total power of the radio band is less than the reference value, determining the corresponding area as a relay service unavailable area, and may not perform the determining as the service FA. When the value obtained by subtracting the out-of-service power from the total power of the radio band is greater than or equal to the reference value, determining the service FA is performed.

The power measurement may include: converting the radio signal into a digital IF signal and then performing a fast Fourier transform (FFT) operation at a predetermined operation point (p); Converting the fast Fourier transformed result to a dB scale; And using the result converted into the dB scale, the following equation,

,

,

Can be calculated according to the step of calculating the power.

Here, the FFTresult _dBscale (i) is a result of the FFT operation converted to the dB scale, f _offset is an offset frequency value for adjusting the starting point to 0 Hz when the radio signal is converted into a digital signal, fs is de The sampling frequency when converting to the low IF signal, BW is the bandwidth of the frequency band to measure power, fc is the center frequency of BW, i is 0≤i <p, p = operation point.

In addition, the FFTresult _dBscale (i) is the following equation,

에 의해 계산될 수 있다. 여기서, 상기 FFTresult_re(i)는 고속푸리에변환(FFT) 연산결과의 실수부의 값이고, FFTresult_im(i)는 고속푸리에변환(FFT) 연산결과의 허수부의 값이다.

Can be calculated by Here, the FFTresult _re (i) is a value of the real part of the fast Fourier transform (FFT) calculation result, FFTresult _im (i) is the value of the imaginary part of the fast Fourier transform (FFT) calculation result.

An ICS wireless repeater according to another embodiment of the present invention, the down converter unit for converting a radio signal into a baseband analog signal; An ADC unit converting the analog signal into a digital signal; An ICS operation unit which performs an interference cancellation algorithm on the digital signal of the ADC unit; A bandpass filter to remove noise due to the interference cancellation; A DAC unit for converting an output of the filter unit into an analog signal; An up-converter unit amplifying the output of the DAC unit and outputting the amplified signal as a wireless signal; And a FA determining unit for detecting a service FA of a corresponding region based on the digital signal of the ADC unit and setting coefficients of the filter unit to be suitable for filtering the detected service FA.

The ICS wireless repeater according to the present invention detects a service FA being serviced in a corresponding region and sets a coefficient of a band pass filter optimized for the detected service FA, so that the ICS wireless repeater is generated around the service FA generated during the ICS operation. In addition to effectively eliminating noise, it is possible to improve Adjacent Channel Leakage Ratio (ACLR) or Adjacent Channel Power Ratio (ACPR). Furthermore, the ICS repeater of the present invention can effectively detect the service FA in consideration of the surrounding noise level.

Therefore, the installation and the manager of the ICS repeater of the present invention can install the ICS repeater even without a separate setting in consideration of the surrounding wireless situation.

The ICS repeater of the present invention determines that the FA is a service FA when the difference between the power measured at a specific FA and the power measured at an out-of-service band is greater than or equal to the reference offset value. As the power in the band itself becomes higher or lower, it is possible to eliminate the error caused by the change in the power of the noise.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the drawings.

1 is a block diagram of a wireless repeater according to an embodiment of the present invention.

The wireless repeater 100 of the present invention is provided in an area where radio signals of at least one base station are received according to Code Division Multiplex Access (CDMA) or Wideband CDMA (WCDMA) protocols to relay radio signals between the base station and the mobile terminal. Can be. The wireless repeater 100 may be used for uplink from a terminal to a base station as well as a downlink from a base station to a terminal for frequency division duplex (FDD). The following description mainly focuses on the example used for the downlink. According to an embodiment, it is possible to design a repeater for relaying a radio signal in both directions using the wireless repeater 100 of FIG.

The wireless repeater 100 of the present invention may be used in various types of wireless repeaters, but is preferably an ICS (Interference Cancellation System) wireless repeater.

In this case, the wireless repeater 100 detects all FAs (hereinafter referred to as 'service FAs') currently being serviced in a region (sector or cell) from the received radio signal, and filters only the detected service FA frequency bands. According to the ICS operation, noise generated around the service FA may be removed.

In order to detect the service FA, the wireless repeater 100 of FIG. 1 detects the service FA by using a received signal to calculate channel power for each FA. Furthermore, the wireless repeater 100 filters noise components around the service FA generated during the ICS operation by setting coefficients optimized for the service FA based on the detected service FA frequency.

Referring to FIG. 1, the wireless repeater 100 of the present invention includes a first antenna 101, a down-converter 103, an analog to digital converter 105, and an ICS calculator 107. ), An ICS repeater including a filter unit 109, a digital to analog converter (DAC) 111, an up-converter 113, a second antenna 115, and a FA determination unit 130. Is an example.

The down converter unit 103 receives a radio signal of a downlink (or forward channel) of at least one base station through the first antenna 101 and converts the radio signal into an IF (Intermediate Frequency) signal (or baseband signal). .

The down converter unit 103 may include an impedance matching unit connected to the first antenna 101, a low noise amplifier (LNA) for minimizing and amplifying noise of a signal passing through the impedance matching unit, and a band pass filter connected to the low noise amplifier (BPF: Band Pass Filter), a mixer for converting to an IF signal, and a local oscillator (LO).

The ADC unit 105 converts the signal output from the down converter unit 103 into a digital signal and outputs the digital signal.

The ICS operator 107 removes the interference signal from the digital IF signal received from the ADC 105 by using a predetermined ICS algorithm and provides the filter 109 to the filter 109. Since the radio signal received through the first antenna 101 for reception includes an interference signal including multiple fading signals in addition to the downlink radio signal from a base station (not shown), the interference signal is included in the ICS calculator 107. Remove).

The filter unit 109 is a finite impulse response (FIR) band pass filter whose coefficient is controlled by the FA determination unit 130, and the digital signal output from the ICS operator 107 is' Filter out the service FA 'band and output it. The filter unit 109 has a frequency response characteristic suitable for filtering all 'service FAs' being serviced in the area where the wireless repeater 100 is installed by the FA determination unit 130.

The filter unit 109 not only removes out-of-band noise included in the digital signal from which the interference signal is removed by the ICS operation unit 107, but also an Adjacent Channel Leakage Ratio (ACLR) or an adjacent channel power ratio (ACLR). ACPR: Improve Adjacent Channel Power Ratio.

The DAC unit 111 converts the digital signal that has been filtered by the filter unit 109 into an analog signal.

The up-converter 113 converts an IF signal (or baseband signal), which is an analog signal output from the DAC unit 111, into an original wireless signal and outputs the converted original signal through the second antenna 115. The signal filtered through the filter unit 109 and output from the DAC unit 111 is filtered to include only the signal of the service FA frequency, and is transmitted to the main service FA of the region where the wireless repeater 100 is installed. The signal corresponds.

The up-converter 113 amplifies the local oscillator LO, a mixer for converting IF signals into a wireless signal, a bandpass filter for bandpass filtering the output signal of the mixer, and an output of the bandpass filter. It may include a power amplifier (Power Amp).

In brief, the wireless relay process centering on the above configuration, the radio signal transmitted from the base station to the mobile terminal is the first antenna 101 → down converter unit 103 → ADC unit 105 → ICS operation unit 107 → The filter unit 109 → DAC unit 111 → up-converter unit 113 → second antenna 115 is filtered and again amplified and transmitted again to the mobile terminal.

The FA determining unit 130 includes a signal capturing unit 131, an FFT calculating unit 133, a channel power calculating unit 135, and a service FA detecting unit 137, and outputs a digital IF signal output from the ADC unit 105. Processing detects the main 'service FA' in the area where the wireless repeater 100 is installed, and sets and controls the coefficients of the filter unit 109 to be suitable for filtering the detected service FA.

The signal capture unit 131 captures and stores the digital signal output from the ADC unit 105, and periodically provides the stored data to the FFT operator 133. The signal capture unit 131 preferably captures 256 to 1024 points of data depending on the amount of FFT operation.

The FFT operator 133 extracts a frequency spectrum from the data provided from the signal capture unit 131. Since the digital data provided by the signal capture unit 131 is data in the time domain, the frequency spectrum can be confirmed by performing fast Fourier transform on the data. The FFT operator 133 may process 256, 512, or 1024 operation points. The higher the computation point, the more accurate spectral components can be extracted, but more computation time is required, so the computation point is sufficient to calculate the effective channel power.

The channel power calculator 135 calculates each 'FA-channel power', 'wireless band total power' and 'out-of-band power' by using the signal spectrum extracted and provided by the FFT operator 133. The FA detection unit 137 is provided.

Here, the 'channel-by-FA power' refers to the power of a radio signal received in each FA band, and the 'wireless band total power' refers to the power of all radio bands (all FAs) that the wireless repeater 100 can relay service. Say

In addition, "service out-of-band power" refers to power of noise as power in a frequency band in which no wireless signal is serviced. The frequency band without a serviced radio signal refers to a frequency band determined to be without a radio signal without distinguishing whether it is a serviceable frequency band. FAs that can be relay service may also be FAs that are not being serviced in the area.

FIG. 2 is a diagram illustrating a frequency band required for describing the present invention. Referring to FIG. 2, a radio band BW _T of an entire FA capable of relaying service is illustrated as a 20 MHz bandwidth of 2110 to 2130 MHz. . The frequency bands BWout ₁ to BWout ₆ are shown without a serviced radio signal outside of BW _T. Any _{one of} BWout ₁ to BWout ₆ can be selected to measure out-of-service power. In the case of WCDMA, each of BWout ₁ to BWout ₆ would be preferably 3.84 MHz.

The calculation method of 'channel-by-FA power', 'wireless band total power' and 'out-of-service band power' of the channel power calculator 135 will be described again below.

The service FA detection unit 137 is provided in the area where the wireless repeater 100 is installed by using 'FA-channel power', 'wireless band total power', and 'service band out of power' provided from the channel power calculator 135. After determining the 'service FA' in service, various coefficients of the filter unit 109 are generated to match the service FA, and the coefficients of the filter unit 109 are set.

According to an exemplary embodiment, the service FA detector 137 may use a predetermined fixed value as the 'out-of-band power' value instead of the value calculated by the channel power calculator 135.

Hereinafter, referring to FIG. 3, a calculation method of each 'FA-channel power', 'wireless band total power', and 'out-of-band power' of the channel power calculator 135 will be described. FIG. 3 is a flowchart provided to explain an operation of a channel power calculator based on power calculation of 'FA-by-FA power', 'wireless band total power', and 'out-band power' according to an embodiment of the present invention. .

When the FFT calculator 133 performs a fast Fourier transform (FFT) operation on the digital data provided from the signal capture unit 131 and provides the FFT to the channel power calculator 135 (S301), the channel power calculator 135 Converts the FFT calculation result of the FFT operation unit 133 to a dB scale. The FFT calculation result has a real part and an imaginary part of a linear scale. Equation 1 below may be used to convert this value to a dB scale (S303).

Here, FFTresult _re (i) is the value of the real part of the FFT calculation result of the FFT calculation unit 133, FFTresult _im (i) is the value of the imaginary part of the FFT calculation result of the FFT calculation unit 133, FFTresult _dBscale (i) is FFT calculation result converted to dB scale. i is 0≤i <p, p is a calculation point may correspond to 256, 512, 1024 and the like.

The channel power calculator 135 reduces the calculation error by obtaining an average value of the FFT calculation results (dB scales) calculated by repeating steps S301 to S303 a predetermined number of times (for example, 50 times) (S305 and S307).

The channel power calculator 135 calculates the channel power for each FA as shown in Equation 2 below based on the average value of the FFT calculation result (S309).

Equation 2 shows a method for calculating FA-channel power.

here,

,

,

이다.

to be.

Here, W _FA (k) is the channel power of the k-th FA, and f _FA (k) is the center frequency of the k-th FA to be calculated. The BW _FA represents the bandwidth of the FA, and CDMA (BW _FA = 1.23 MHz) and WCDMA (BW _FA = 3.84 MHz) have different values. f _offset is an offset frequency value for adjusting the starting point to 0 Hz when the ADC unit 105 converts the digital signal, and is a fixed value related to the sampling ratio of the ADC unit 105, and fs is a sampling frequency of the ADC unit 105. Say. p is a point for FFT operation, such as 256, 512 or 1024. FFTresult _dBscale (i) is the average value of the FFT calculation result converted to the dB scale, and floor (x) represents the truncation of the decimal point in x. For example, floor (23.7) = 23.0.

When the calculation of the FA-channel power for each FA is made in step S309, the channel power calculator 135 calculates the 'wireless band total power'. Similar to the FA-channel power calculation, the calculation of 'Wireless Bandwidth Full Power' uses the FFT calculation result converted to dB scale, and the FFT calculation result calculated by repeating a predetermined number of times (for example, 50 times) to reduce the calculation error. Use the average of these. Equation 3 below is a calculation method of 'wireless band full power' (S311).

here,

,

,

이다.

to be.

In addition, W _Total denotes the 'Wireless Band Total Power', BW _T denotes the bandwidth of the entire FA that can be relayed to be calculated, and fc _-Total denotes the center frequency of the BW _T which is the entire FA band. In the case of Figure 2, BW _T is 20 MHz, fc _-Total is 2120 MHz.

When the 'wireless band total power' is calculated in step S311, the channel power calculator 135 calculates a reference power value (that is, power of noise) for the case where there is no radio signal, 'out of band power'. Calculate Equation 4 below shows a calculation method of 'out-of-service power' (S313).

 here,

,

,

이다.

to be.

Wout is 'out-of-service power' and BWout is a frequency band where no wireless signal is serviced. It is preferable that BWout be equal to the BW _FA , which is the bandwidth of each FA, as shown in Fig. 2 (in the case of WCDMA, 3.84 MHz in BWout), since it can eliminate the error of the determination of the service FA. fc-out is the center frequency of BWout. For example, if BWout ₁ of FIG. 2 is 3.84 MHz, fc-out ₁ would be 2108.08 MHz.

By the above method, the channel power calculator 135 may calculate 'FA-specific channel power', 'wireless band total power', and 'out-of-service band power'. It can be represented by the equation (5).

,

,

Here, W is the power to be measured, BW is the bandwidth of the band to measure power, fc is the center frequency of the band BW to measure power.

In addition, although the calculation of each power in the steps S309 to S313 is described in time series, it does not need to be in the order as shown in FIG.

Hereinafter, the service FA detection method and the filter unit 109 coefficient setting method of the service FA detection unit 137 will be described with reference to FIG. 4. 4 is a flowchart provided to explain an operation of a service FA detection unit according to an embodiment of the present invention.

When the channel power calculator 135 calculates the channel power, 'wireless band total power' and 'out-band power' for each FA and provides the service FA detector 137 (S401), the service FA detector 137 Uses these values to determine whether the area is an area where wireless relay service is available. To this end, the service FA detection unit 137 determines whether the value obtained by subtracting the out-of-band power (Wout) from the _total wireless band power (W _Total ) is greater than or equal to a predetermined reference value. At this time, the reference value is preferably about 5 dBm or more in consideration of the error in the power calculation (S403).

If the value obtained by subtracting the out-of-band power (Wout) from the _total wireless band power (W _Total ) is equal to or greater than a predetermined reference value, the service FA detection unit 137 determines that the corresponding area is a normal wireless relay serviceable area. It is determined whether the value obtained by subtracting the out-of-service power (Wout) from the channel power (W _FA (k)) is greater than or equal to the reference value (S405 and S407).

Based on the determination result of step S407, the service FA detection unit 137 determines that the FA having the value obtained by subtracting the out-of-service power (Wout) from the corresponding FA-channel power (W _FA (k)) is a service FA. In operation S409, a FA whose value obtained by subtracting the service out-of-band power Wout from the corresponding FA-channel power W _FA (k) is less than the reference value is determined as an unserviced FA (S411).

The service FA detection unit 137 repeats the above steps S407 to S411 for all FAs (S413 and S415).

If at least one service FA is detected, the service FA detection unit 137 generates and sets the coefficients of the filter unit 109 to match the characteristics of the detected service FA (S417).

If, in step S403, the result of subtracting the out-of-band power (Wout) from the _total wireless band power (W _Total ) is less than a predetermined reference value, the service FA detection unit 137 determines that the corresponding area is a normal wireless relay service unavailable area. It determines and does not provide a wireless relay service (S419).

In this manner, the service FA detection of the service FA detection unit 137 of the present invention and the filter coefficient setting according thereto are performed.

The reference value in step S403 or S407 is set to at least about 5 dBm or more, but the reference values in the two steps do not necessarily have to match. If the reference value is increased, the error of the service FA determination is reduced, but the channel power of the service FA is lower than the reference value in the zone where the radio signal strength is low, so that accurate determination cannot be made.

To this end, the service FA detection unit 137 may set a plurality of reference values, and selectively apply different reference values according to the size of the _{total Wband} power provided from the channel power calculator 135.

FIG. 5 is a flowchart provided to explain an example of a method of detecting, by the channel power calculator of the present invention, a center frequency fc-out for obtaining out-of-service power. In the following, the channel power calculator 135 obtains Wout. An example of how to select fc-out and BWout will be described.

First, the channel power calculator 135 adjusts the RF gain of the down converter 103 for fc-out detection. The RF gain for fc-out detection is preferably the minimum value among the values in which the power of the entire radio band BW _T measured at the corresponding gain is larger than the reference power. The reference power is a preset value measured as the noise power of the repeater 100 itself when no signal is input (S501).

The channel power calculator 135 obtains power of a band other than the service band BW _T , for example, BWout _{1 in} the same manner as in Equation 4 (S503).

The channel power calculator 135 calculates a value obtained by subtracting the reference power of step S501 from the power obtained in step S503, and determines whether the calculated value is within a band power offset range. The offset of the band power is to reflect an error that may occur during power calculation in step S503, and a value within +/- 3 dBm is generally preferable (S505).

As a result of the determination in step S505, if the value obtained by subtracting the reference power from the obtained power of the corresponding band is within the offset range, the final determination of the corresponding band as BWout to be applied to Equation 4 to obtain Wout, and the center frequency of the BWout fc-out It is determined as (S507).

If it is determined in step S505 that the value obtained by subtracting the reference power from the obtained power of the corresponding band is outside the offset range, another BWout, for example, BWout ₂ is selected, and the procedure after step S503 is repeated (S509).

The range of BWout that can be changed and selected in step S509 is related to the sampling clock clock used in the ADC unit 105 of the repeater 100. For example, if the sampling frequency fs of the ADC unit 105 is 60 MHz, the measurable wireless bandwidth will be 30 MHz, and only BWout ₁ and BWout ₄ will be possible in FIG.

In this manner, the channel power calculator 135 of the present invention can select the BWout for obtaining the Wout. As mentioned above, the service FA detector 137 may use a predetermined fixed value other than the value calculated by the channel power calculator 135 as 'out-of-band power' or may be selected from among the serviceable bands BW _T. It may be.

The ICS wireless repeater 100 of the present invention described above may detect the service FA and set the coefficient of the filter unit 109 to be suitable for filtering the detected service FA.

6 is a frequency spectrum of a signal output from the ADC unit of the present invention, FIG. 7 is a diagram illustrating an example of setting a filter coefficient according to service FA detection, and FIG. 8 is a frequency spectrum of a signal output from the DAC unit.

6 to 8 are measured by inputting four FA WCDMA radio signals (-65 dBm), and the _total wireless band power (W _Total ) is -65.19 dBm, and the service band power (Wout) is It was measured at -77.94 dBm. W _Total -W _out = 12.75 dBm, which corresponds to the relay serviceable area. The calculation result of step S407 according to FA-channel power of four FAs is shown in Table 1 below.

FA index (k) W _FA (k) (dBm) W _FA (k)-Wout (dBm) One -69.94 8.00 2 -70.22 7.72 3 -76.69 1.25 4 -72.12 5.82

Therefore, according to the result of Table 1, 1, 2, and 4 FA become service FA. Accordingly, the coefficient of the filter unit 109 is set as shown in FIG.

The coefficient setting of FIG. 7 shows setting values of 128 taps of an 8 bit FIR filter.

The output signal of the ADC unit 105 as shown in FIG. 6 has been improved as shown in FIG. 8 while the interference cancellation and the filtering unit 109 are filtered. It can be seen that noise due to interference cancellation (ICS) is removed and adjacent channel leakage facilities (ACLR) or adjacent channel power ratio (ACPR) are improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

1 is a block diagram of a wireless repeater according to an embodiment of the present invention;

2 is a diagram showing a frequency band required for explaining the present invention;

3 is a flowchart provided to explain an operation of a channel power calculator according to an embodiment of the present invention;

4 is a flow chart provided in the operation description of the service FA detection unit according to an embodiment of the present invention;

5 is a flowchart provided to explain a method of detecting a center frequency fc-out for obtaining power out of band by the channel power calculator of the present invention;

6 is a frequency spectrum of a signal output from the ADC unit of the present invention,

7 is a diagram illustrating an example of setting filter coefficients according to service FA detection;

8 is a frequency spectrum of a signal output from the DAC unit.

Claims (9)

In the wireless relay method of the ICS wireless repeater for outputting a wireless signal after performing an ICS (Interference Cancellation System) operation for the wireless signal in accordance with the CDMA or WCDMA regulations, Calculating FA-channel power, which is power of a radio signal of each FA frequency band, and out-of-service power, which is power of a band where no wireless relay service is provided; Determining, as a service FA, an FA having a channel-specific power for each FA whose difference with the out-of-service power is greater than a reference value among the channel-specific powers for each FA; And And setting a coefficient of a band pass filter operating after the ICS operation based on the determined service FA to remove noise according to the ICS operation. The method of claim 1, Calculating the total power of the radio band which is the power of the whole band available for wireless relay service; And When the value obtained by subtracting the out-of-service power from the total power of the radio band is less than the reference value, determining that the service area is a relay service unavailable area further includes not performing the step of determining the service FA. And determining the service FA when the value obtained by subtracting the out-of-service power from the total power of the radio band is equal to or greater than the reference value. The method of claim 2, Each of the power measurements, Converting the radio signal into a digital IF signal and then performing a fast Fourier transform (FFT) operation at a predetermined operation point (p); Converting the fast Fourier transformed result to a dB scale; And Using the result converted to the dB scale, the following equation,

,

Follow the steps to calculate power according to, The FFTresult _dBscale (i) is a result of the FFT operation converted to the dB scale, f _offset is an offset frequency value for adjusting the starting point to 0 Hz when the radio signal is converted into a digital signal, fs is a digital IF Sampling frequency when converting to a signal, BW is the bandwidth of the frequency band to measure power, fc is the center frequency of BW, i is 0≤i <p, p is a fast Fourier transform (FFT) operation point Wireless relay method of ICS wireless repeater. The method of claim 3, The FFTresult _dBscale (i) is the following equation,

Is calculated by The FFTresult _re (i) is a value of the real part of the fast Fourier transform (FFT) calculation result, FFTresult _im (i) is a value of the imaginary part of the fast Fourier transform (FFT) calculation result, the wireless relay method of the ICS wireless repeater . delete A down converter unit converting a radio signal into a baseband analog signal; An ADC unit converting the analog signal into a digital signal; An ICS operation unit which performs an interference cancellation algorithm on the digital signal of the ADC unit; A bandpass filter to remove noise due to the interference cancellation; A DAC unit for converting an output of the filter unit into an analog signal; An up-converter unit amplifying the output of the DAC unit and outputting the amplified signal as a wireless signal; And A FA determining unit for detecting a service FA of a corresponding region based on the digital signal of the ADC unit and setting coefficients of the filter unit to be suitable for filtering the detected service FA; The FA determination unit, An FFT calculation unit performing fast Fourier transform on the digital signal of the ADC unit; After converting the fast Fourier transformed result to a dB scale, and using the fast Fourier transformed result of the dB scale, the FA-specific channel power, which is the power of the radio signal of each FA frequency band and the band of the band for which no wireless relay service is provided A channel power calculator for calculating out-of-band power, which is power; And A service having a FA having a channel power of each FA whose difference with the out-of-service power of the FA-channel power is greater than or equal to a reference value as a service FA, and setting a coefficient of the filter unit based on the determined service FA. ICS wireless repeater comprising a FA detection unit. The method of claim 6, The channel power calculation unit calculates the radio band total power, which is the power of the entire band available for wireless relay service, and provides the calculated power to the service FA detection unit. The service FA detection unit, when the value obtained by subtracting the out-of-service power from the total power of the radio band is less than the reference value, determines that the area is a relay service unavailable area and does not perform the operation of determining the service FA. ICS wireless repeater. 8. The method according to claim 6 or 7, The power measurement of the channel power calculator, Using the fast Fourier transform result of the dB scale, the following equation,

,

Calculate according to The FFTresult _dBscale (i) is a result of the FFT operation converted to the dB scale, f _offset is an offset frequency value for adjusting the starting point to 0 Hz when the radio signal is converted into a digital signal, fs is a digital IF Sampling frequency when converting to a signal, BW is the bandwidth of the frequency band to measure power, fc is the center frequency of BW, i is 0≤i <p, p is a fast Fourier transform (FFT) operation point ICS wireless repeater. The method of claim 8, The FFTresult _dBscale (i) is the following equation,

Is calculated by The FFTresult _re (i) is a value of the real part of the fast Fourier transform (FFT) operation result, FFTresult _im (i) is an imaginary part of the fast Fourier transform (FFT) operation result.

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