KR100957818B1 - Mobile ics repeater and materializing embodiment method for the same - Google Patents

Abstract

The present invention relates to a radio interference cancellation repeater used in a mobile communication system. The present invention provides a wireless interference signal removing repeater for estimating filter taps that are operated at regular intervals and removing interference signals by applying an adaptive filter that performs filtering for only the corresponding filter taps. According to the present invention, by reducing the amount of computation required for filtering the signal in the radio interference elimination repeater, by reducing the amount of heat generated by the device performing the operation to increase the reliability of the radio interference elimination repeater, because the low-cost device can be used While lowering the cost of, there is an effect that the performance similar to the conventional radio interference signal cancellation performance is provided.

Interference signal elimination, shaping filter, image elimination filter, adaptive filter

Description

Wireless interference elimination repeater and its implementation method {MOBILE ICS REPEATER AND MATERIALIZING EMBODIMENT METHOD FOR THE SAME}

The present invention relates to a radio interference cancellation repeater used in a mobile communication system.

In general, a mobile communication system attempts to satisfy a service quality of a mobile communication in a corresponding area by installing a repeater in an area covering a radio shade area or a burden of installing a base station.

The repeater is divided into a wired repeater connected to the base station by wires such as an optical cable and a wireless repeater connected to the base station by wireless.

The wired repeater can maintain good call quality because wired communication is performed between the repeater and the base station, but it is more expensive than the wireless repeater and the installation cost of the wired line and the lease cost are considerable. On the contrary, since the wireless repeater communicates wirelessly between the repeater and the base station, the call quality is lower than that of the wired repeater, but the installation and operation cost is low, and the place where the electromagnetic wave is shielded by the structure such as the basement inside the building In the case of installing a repeater in a narrow space, such as can be more appropriate than the expensive wired repeater.

However, if the wireless repeater is installed in an open area rather than a narrow space such as the inside of a building, a part of the transmitted signal output through the transmit antenna of the repeater is fed back to the receiving antenna and mixed with the original received signal. Can be. In such a case, signal interference may occur and a repeater may be oscillated, thereby making it difficult to provide a normal service, and in the worst case, may cause a base station failure. Due to this problem, the wireless repeater has been used only in limited places such as the basement inside the building.

However, the advantages of the wireless repeater that the installation and operation cost is cheaper than the wired repeater is still attractive, and the technology that can eliminate the interference of the feedback signal has emerged. The wireless repeater to which the present technology is applied is called a wireless interference signal cancellation repeater or an interference cancellation system (ICS) repeater.

1 is a block diagram showing a conventional radio interference signal cancellation repeater.

Conventional radio interference elimination repeater, the donor antenna 10, the receiver 20, the A / D converter 30, the digital unit 40, the D / A converter 50, the transmitter 60 and the service antenna It consists of 70.

The donor antenna 10 receives the RF signal from the base station side and outputs the RF signal to the receiver 20.

The receiver 20 receives a signal received from the donor antenna 10, amplifies, downconverts, and filters the output signal to the service antenna 70.

The A / D converter 30 converts the analog signal output from the receiver 20 into a digital signal and outputs the digital signal.

The digital unit 40 includes a first band pass filtering unit 42, an interference signal removing unit 44, and a second band pass filtering unit 46 to filter the digital signal and remove the interference signal.

The first band pass filtering unit 42 filters only the frequencies required for each FA (Frequency Assignment) in the digital signal converted by the A / D converter 30.

The interference signal removing unit 44 estimates the interference signal from the signal filtered by the first band pass filtering unit 42 and removes the interference signal included in the signal. In this case, an adaptive filter such as a Least Mean Square (LMS) or a Recursive Least Square (RLS) algorithm is used to estimate the interference signal.

The second bandpass filtering unit 46 cleans up the frequency spectrum of the signal by removing small oscillation components that may occur outside the passband from the signal from which the interference signal is removed.

The D / A converter 50 converts the digital signal arranged by the second band pass filtering unit 46 into an analog signal and outputs the analog signal.

The transmitter 60 up-converts, filters, and amplifies the analog signal converted by the D / A converter 50 and outputs the same to the service antenna 70.

The service antenna 70 receives a signal from the transmitter 60 and transmits the signal to the terminal.

As described above, the first band pass filtering unit 42, the interference signal removing unit 44, and the second band pass filtering unit configuring the digital unit 40 as one of the methods of improving the performance of the conventional wireless interference signal removing repeater. In (46), there is a method of increasing the amount of filtering.

However, increasing the amount of calculation in the conventional digital unit 40 increases the amount of calculation in the first and second band pass filtering units 42 and 46 and removes the interference signal in order to improve the frequency spectrum of the signal. In order to increase the performance, the amount of computation of the adaptive filter used in the interference signal canceller 44 must be increased. Increasing the amount of computation in the filtering process requires a large number of filter taps for filtering, thereby increasing the unit cost of the product and increasing the amount of heat generated by the device, thereby degrading the reliability of the radio interference elimination repeater.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a radio interference elimination repeater capable of realizing the same performance as a conventional radio interference elimination repeater while reducing the amount of computation required for filtering in the digital unit. .

In order to achieve the above object, the present invention, the receiving unit for receiving a signal; An interference signal removing unit for removing the interference signal from the received signal; A transmitter for transmitting a signal; The interference signal removing unit may include: an adaptive filter which estimates the filter taps at regular intervals and estimates the interference signal through an operation for filtering only at the corresponding filter taps; It provides a wireless interference signal removal repeater comprising a.

In this case, the adaptive filter includes: filter tap estimating means for estimating a coefficient of the filter tap; And transversal filtering means for calculating and filtering only filter taps corresponding to coefficients of the filter tap estimated by the filter tap estimating means. Wherein the filter tap estimating means estimates the coefficients of the filter taps at regular intervals such that the filter taps are partially calculated by the transverse filtering means.

In addition, a first band pass filtering unit for filtering only a signal of a desired band between the receiver and the interference signal canceller; The filter included in the first bandpass filtering part further includes a filter formed by forming filter taps having a tap coefficient of zero at regular intervals so that calculation is not performed, and simultaneously passing a desired band and an image band. It provides a wireless interference signal cancellation repeater, characterized in that (Shaping Filter).

And a second band pass filtering unit for filtering only signals having a desired band between the interference signal removing unit and the image removing filtering unit. The filter included in the second band pass filtering part further includes a filter formed by forming filter taps having a zero tap coefficient at regular intervals so that calculation is not performed, and simultaneously passing a desired band and an image band. It provides a wireless interference signal cancellation repeater, characterized in that.

Also, an image rejection filtering unit for removing an unnecessary image band generated in the signal before transmitting the signal from which the interference signal is removed; It provides a wireless interference signal removal repeater further comprising.

On the other hand, the receiving step of receiving a signal; An interference signal removing step of removing the interference signal from the received signal; And a transmitting step of transmitting a signal from which the interference signal has been removed. The interference signal removing step includes: a filter tap estimating step of estimating a coefficient of the filter tap; A transversal filtering step of calculating and filtering only filter taps corresponding to the filter tap coefficients estimated in the filter tap estimating step; And the filter tap estimating step includes estimating the coefficients of the filter taps at regular intervals such that only some of the filter taps are calculated in the transverse filtering step.

In addition, a first band pass filtering step of filtering only signals of a desired band between the receiving step and the interference signal removing step; The filter used in the first band pass filtering step may include a filter formed by forming filter taps having a tap coefficient of zero at regular intervals so as not to perform calculation, and simultaneously passing a desired band and an image band. Provides a method for implementing a wireless interference signal cancellation repeater, characterized in that.

And a second band pass filtering step of filtering only signals of a desired band between the interference signal removing step and the image removing filtering step. The filter used in the second band pass filtering step further includes a filter formed by forming filter taps having zero tap coefficients at regular intervals so as not to perform calculation, and simultaneously passing a desired band and an image band. Provides a method for implementing a wireless interference signal cancellation repeater, characterized in that.

In addition, the image removal filtering step of removing the unnecessary image band generated in the signal before transmitting the signal from which the interference signal is removed; It provides a method for implementing a wireless interference signal removal repeater further comprising a.

As described above, according to the present invention, by reducing the amount of computation required for filtering the signal in the radio interference elimination repeater, it reduces the amount of heat generated by the device on which the operation is performed to increase the reliability of the radio interference elimination repeater, low-cost device Can be used to reduce the cost of the product, but there is an effect that the performance similar to the conventional radio interference signal cancellation performance is provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

<Description of configuration>

Figure 2 is a block diagram showing a radio interference rejection repeater of the present invention.

The wireless interference signal removing repeater 100 of the present invention includes a donor antenna 110, a receiver 120, an A / D converter 130, a digital unit 140, a D / A converter 150, and a transmitter 160. And a service antenna 170.

The donor antenna 10 receives an RF signal from the base station and outputs it to the receiver 120.

The receiver 120 receives a signal received from the donor antenna 110, amplifies, downconverts, and filters the output signal to the service antenna 170.

The A / D converter 130 converts the analog signal output from the receiver 120 into a digital signal and outputs the digital signal.

The digital unit 140 includes a first band pass filtering unit 142, an interference signal canceling unit 144, a second band pass filtering unit 146, and an image removal filtering unit 148. It is preferable that the device is implemented with a field-programmable gate array (FPGA) or a digital signal processor (DSP).

The first band pass filtering unit 142 is composed of a shaping filter, and the signal output from the A / D converter 130 passes through the shaping filter of the first band pass filtering unit 142 and has a desired band. And unnecessary image band signals are output.

The interference signal removing unit 144 includes an adaptive filter 145, which includes a filter tap estimating means 145a and a transverse filtering means 145b.

The filter tap estimating means 145a estimates the coefficient of the filter tap.

The transverse filtering means 145b calculates and filters only the filter tap whose coefficient of the filter tap is estimated by the filter tap estimating means 145a, and outputs a signal of a desired band and an unnecessary image band in the signal.

In this case, the filter tap estimating means 145a estimates the coefficients of the filter taps at regular intervals rather than estimating the coefficients of all the filter taps so that the transverse filtering means 145b calculates all the filter taps. That is, the filter tap estimating means 145a estimates only coefficients of the filter tap corresponding to the odd number or only coefficients of the filter tap corresponding to the even number. Of course, only the coefficients of the filter tap corresponding to one set may be estimated or more.

Thus, in the transverse filtering means 145b, as described above, the filter tap estimating means 145a performs the filtering operation only on a part of the filter taps in which the coefficient of the filter tap is estimated. It has the advantage of being reduced.

The second band pass filtering unit 146 is formed of a shaping filter, and the signal output from the interference signal removing unit 144 passes through the shaping filter of the second band pass filtering unit 146 and the desired band and unnecessary image bands. The signal is output.

The image removal filtering unit 148 removes an unnecessary image band from the signal passing through the second band pass filtering unit 146 and outputs only a component having a desired band. In this case, the image band is generated while the signal is filtered by the first band pass filtering unit 142, the transverse filtering unit 145b, and the second band pass filtering unit 146.

The D / A converter 150 converts the digital signal output from the image removal filtering unit 148 into an analog signal and outputs the analog signal.

The transmitter 160 up-converts, filters, and amplifies the analog signal converted by the D / A converter 150 and outputs the converted analog signal to the service antenna 170.

The service antenna 170 receives a signal from the transmitter 160 and transmits the signal to the terminal.

Therefore, as described above, by reducing the amount of computation in the digital unit 140, the amount of heat generated in the FPGA or DSP on which the digital unit 140 is implemented can be reduced, and the low-performance FPGA or DSP can achieve the same performance as in the prior art. There is an advantage.

On the other hand, the calculation method of the adaptive filter of the interference signal removing unit is applied to the method used in the shaping filter, Figure 3 is shown to explain the calculation process for filtering in the shaping filter Interpolated composed of a shaping filter and an image removing filter FIR filter. In FIG. 4, only the frequency of a desired band is filtered by the shaping filter and the image removing filter, and FIG. 5 shows only the filter tap calculated in the shaping filter.

The interpolated FIR filter 200 includes a shaping filter 210 and an image-rejection filter 220. The signal passing through the shaping filter 210 outputs a signal of a desired frequency band and an unnecessary image band together. Therefore, the image band must be removed again from the signal passing through the shaping filter 210. Therefore, the signal must pass through the shaping filter 210 and then pass through the image removal filter 220 again.

Referring to FIG. 4, as shown in the graph of FIG. 4A, a frequency band and an image band of a desired band are output together with a signal passing through the shaping filter 210. Then, the signal passing through the shaping filter 210 passes the signal through the image removal filter 220 having a pass band as shown in (b) of FIG. 4, so that the frequency band of the desired band as shown in (c) of FIG. The signal having is output.

In this case, as shown in FIG. 5, the shaping filter 210 has the same number of general FIR filters and filter taps. However, since the coefficient of the tap becomes 0 (Zero) at regular intervals by the interpolation, the calculation is not performed in the filter tap having the coefficient of 0 (Zero). Therefore, the amount of computation can be reduced compared to the general FIR filter. The filter tab of the shaping filter 210 shown in FIG. 5 illustrates a case where the interpolation expansion factor is 2, and in practice, the value of the factor may be changed in some cases. As the value of the factor increases, the shaping filter ( The amount of computation at 210 is reduced.

However, when the value of the factor decreases and the amount of calculation in the shaping filter 210 decreases, much unnecessary image band passes through the shaping filter 210 so that the band of images filtered by the image removal filter 220 increases. The amount of calculation in the elimination filter 220 increases. However, since the amount of computation reduced in the shaping filter 210 is greater than the amount of computation increased in the image removal filter 220, the amount of computation for filtering is reduced compared to the general FIR filter.

In addition, in the wireless interference signal elimination repeater 100 of the present invention, the shaping filter 210 is not applied to only the first and second band pass filtering units 142 and 146, but is adapted to the interference signal elimination unit 144. Since the method similar to that of the shaping filter 210 is applied to the filter 145, the amount of computation required for filtering is significantly reduced.

That is, in the shaping filter 210, the coefficient of the filter tap between the filter taps is set to 0 (Zero) so that the calculation is performed only on the odd-numbered or even-numbered filter taps, as in the case where the factor value is 2, and the adaptive filter ( The filter tap estimating means 145a of 145 estimates the coefficients of the estimated filter tap only odd or even coefficients, and then the transversal filtering means 145b calculates only the filter taps corresponding to the estimated coefficients. Reduce the amount of computation

In addition, in the wireless interference signal removing repeater 100 of the present invention, the image removing filter unit 148 is disposed at the rear end of the second band pass filtering unit 146 and the first and second band pass filtering units 142 and 146. Since unnecessary image bands are removed from the signal passing through the interference signal removing unit 144 at one time, there is an advantage that the amount of computation is reduced than installing the image removing filter 220 at the rear end of each shaping filter 210 is applied. .

<Description of the method>

A method of implementing the interference signal elimination repeater by the wireless interference signal elimination repeater of FIG. 2 having the configuration as described above will be described with reference to the flowchart of FIG.

1. Receive step <S610>

The RF signal is received through the donor antenna 110, amplified and down-converted into an IF signal, and then filtered and output to the service antenna 170.

2. A / D conversion step <S620>

The A / D converter 130 converts the analog signal output in step S310 into a digital signal and outputs the digital signal.

3. First band pass filtering step <S630>

The first band pass filtering unit 142 is composed of a shaping filter 210, the signal of the desired band and the image band is output from the signal passed through step S620. The filter tap of the shaping filter 210 is operated on a filter tap having a zero coefficient by changing the value of the interpolation expansion factor so that the coefficient of the tap has a value of zero at regular intervals according to the value of the factor. Since this operation is not performed, the amount of calculation for filtering is reduced, and signals of a desired band and an unnecessary image band are output together.

4. Interference signal elimination step <S640>

The interference signal removing unit 144 estimates the interference signal from the signal passing through step S630 and removes the interference signal included in the signal. In this process, the interference signal removing unit 144 performs filtering using the adaptive filter 145. The adaptive filter 145 goes through steps S642 and S644 described below.

4-1. Filter tab estimation step <S642>

The filter tap estimating means 145a of the adaptive filter 145 estimates coefficients of the filter taps, and estimates only the odd-numbered or even-numbered coefficients of the estimated filter taps.

4-2. Transversal filtering step <S644>

The transversal filtering means 145b calculates only the filter corresponding to the coefficient of the filter tap estimated in step S642. Therefore, instead of reducing the amount of computation as in step S630, signals of a desired band and an unnecessary image band are output together.

5. Second band pass filtering step <S650>

The second band pass filtering unit 146 is composed of a shaping filter 210, and filtered in the same manner as in step S630, the signal of the desired band and unnecessary image band is output together.

6. Image removal filtering step <S660>

The image removal filtering unit 148 removes unnecessary image bands from the signals passing through the steps S630, S640, and S650 at once, and filters only the desired bands.

7. D / A conversion step <S670>

The D / A converter 150 converts the digital signal that has passed through step S660 into an analog signal and outputs the analog signal.

8. Transmission step <S680>

The transmitter 160 up-converts, filters, and amplifies the signal passed through step S670, and transmits the signal to the terminal through the service antenna 170.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram showing a conventional radio interference signal cancellation repeater.

Figure 2 is a block diagram showing a radio interference rejection repeater of the present invention.

3 is a block diagram showing an Interpolated FIR filter applied to the present invention.

Fig. 4A is a graph showing the frequency band of the signal passing through the shaping filter.

4B is a graph showing the frequency filtering band of the image removal filter.

4 (c) is a graph showing the frequency band of the signal passing through the shaping filter and the image removal filter.

5 is a graph showing filter tabs of a molded filter.

6 is a flowchart illustrating a method of implementing a wireless interference signal elimination repeater according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: wireless interference canceling repeater

140: digital part

142: first band pass filtering unit

144: interference signal removing unit

145: adaptive filter

145a: filter tap estimating means

145b: Transversal filtering means

146: second band pass filtering unit

148: image removal filter

200: Interpolated FIR Filter

210: molding filter 220: image removal filter

Claims (9)

Receiving unit for receiving a signal; An interference signal removing unit for removing the interference signal from the received signal; And A transmitter for transmitting a signal; Including, The interference signal removing unit, An adaptive filter which estimates the filter taps at regular intervals and estimates the interference signal through a calculation for filtering only at the corresponding filter taps; Wireless interference signal removal repeater comprising a. The method of claim 1, The adaptive filter, Filter tap estimating means for estimating a coefficient of the filter tap; And A transversal filtering means for calculating and filtering only filter taps corresponding to coefficients of the filter tap estimated by the filter tap estimating means; Including; And the filter tap estimating means estimates the coefficients of the filter taps at regular intervals so that the filter taps are partially calculated by the transverse filtering means. The method of claim 2, A first band pass filtering unit filtering only signals of a desired band between the receiver and the interference signal canceller; More, The filter included in the first band pass filtering unit, A filter interference having a tap coefficient of zero (Zero) is formed at regular intervals so that the calculation is not performed, it is a shaping filter (Shaping Filter) to pass through the desired band and the image band at the same time. The method of claim 2, A second band pass filtering unit filtering only a signal having a desired band between the interference signal removing unit and the image removing filtering unit; More, The filter included in the second band pass filtering unit, And a filter filter having a tap coefficient of zero (Zero) formed at regular intervals so that a calculation is not performed, and a molded filter for passing a desired band and an image band simultaneously. The method of claim 1, An image-rejection filtering unit for removing an unnecessary image band generated in the signal before transmitting the signal from which the interference signal has been removed; Wireless interference signal removal repeater further comprises. A receiving step of receiving a signal; An interference signal removing step of removing the interference signal from the received signal; And A transmission step of transmitting a signal from which an interference signal has been removed; Including, The interference signal removing step, A filter tap estimating step of estimating a coefficient of the filter tap; And A transversal filtering step of calculating and filtering only filter taps corresponding to the filter tap coefficients estimated in the filter tap estimating step; Including, And the filter tap estimating step estimates coefficients of the filter taps at regular intervals so that only some of the filter taps are calculated in the transverse filtering step. The method of claim 6, A first band pass filtering step of filtering only signals of a desired band between the reception step and the interference signal removing step; More, The filter used in the first band pass filtering step, A method of implementing a wireless interference signal removing repeater, characterized in that the filter tap having a tap coefficient of zero (Zero) is formed at regular intervals so that a calculation is not performed. The method of claim 6, A second band pass filtering step of filtering only signals of a desired band between the interference signal removing step and the image removing filtering step; More, The filter used in the second band pass filtering step, A method of implementing a wireless interference signal removing repeater, characterized in that the filter tap having a tap coefficient of zero (Zero) is formed at regular intervals so that a calculation is not performed. The method of claim 6, An image removal filtering step of removing an unnecessary image band generated in the signal before transmitting the signal from which the interference signal has been removed; Wireless interference signal removal repeater implementation method further comprising a.

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