KR100829763B1 - Interference cancellation method and apparatus for microwave repeaters - Google Patents

Abstract

A method and an apparatus for canceling interference in a mobile communication radio repeater having an overpower prevention function are provided to prevent a strong signal from being outputted to a base station or a terminal fundamentally, thereby securing the stability of field operation. A method for canceling interference in a mobile communication radio repeater having an overpower prevention function comprises the following steps of: detecting a receiving signal outputted from a receiving antenna and an output signal outputted to a transmitting antenna(S401); calculating a weight factor through correlation between the detected receiving signal and output signal(S403); generating an interference canceling signal according to the calculated weight factor(S404); cutting the generated interference canceling signal from the receiving signal, in which an original signal and an interference signal is mixed, to generate a signal in which the interference signal is cancelled(S405); and outputting the signal in a set value to the transmitting antenna when the generated signal is stronger than a reference level and passing through the transmitting antenna when the generated signal is weaker than the reference level(S406).

Description

Interference elimination method and device for wireless repeater with over-output protection {INTERFERENCE CANCELLATION METHOD AND APPARATUS FOR MICROWAVE REPEATERS}

1 is a block diagram of a wireless repeater according to the cited technology.

FIG. 2 is a reference diagram for explaining a problem of the wireless repeater of FIG. 1.

Figure 3 is a block diagram of the main portion of the wireless repeater to which the interference cancellation apparatus according to an embodiment of the present invention is applied.

FIG. 4 is a block diagram of an overpower limiter applied to the interference cancellation device of FIG.

FIG. 5 is a flowchart of an interference cancellation method and an overpower limit performed in the interference cancellation device of FIG. 1.

FIG. 6 is a reference diagram for explaining the overpower limit of FIG. 5.

* Description of the code for the main parts of the drawings *

300: interference elimination device

31: Subtraction

32: weight factor calculation unit

33: interference cancellation signal generation unit

34: Delaybo Government

35: over power limit

35a: comparison means

35b: bypass means

35c: setting value output means

35d: transfer means

S: original signal I: interference signal

R: Received signal ^ S: Output signal

^ I: Interference cancellation signal Err: Signal after interference cancellation

Ref: Reference signal for interference cancellation W: Weighting factor

The present invention relates to an interference cancellation method and apparatus for a wireless repeater for mobile communication.

In general, it is intended to satisfy the service quality of mobile communication in the area by constructing a repeater in the area covering the radio shade area or the burden of the installation cost of the 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. However, the wired repeater is more expensive than the wireless repeater.

On the contrary, since the wireless repeater performs wireless communication between the repeater and the base station, the call quality is lower than that of the wired repeater, but the installation and operation costs are low.

Such a wireless repeater may be more appropriately applied than an expensive wired repeater when the area covered by the repeater is small due to the electromagnetic shielding effect of the structure such as the basement inside the building.

However, if the wireless repeater is installed in an open area, not inside the building, the transmission signal through the transmitting antenna of the wireless repeater is fed back to the receiving antenna and mixed with the original receiving signal, resulting in signal interference or oscillation. Not only do not provide services, but in the worst case will cause base station failure. Due to this problem, the wireless repeater has been used only in limited places such as the basement inside the building as described above.

However, the advantages of the wireless repeater that the installation and operation cost is cheaper than the wired repeater is still attractive, and technology has been introduced to remove the interference of the feedback signal, thus eliminating the interference of the feedback signal. The wireless repeater to which the present technology is applied is called an interference cancellation system (ICS) repeater.

Conventional interference elimination techniques include techniques using the analog method disclosed in Korean Laid-Open Patent Publication No. 2003-0017171, techniques using the digital method described in Korean Laid-Open Patent Publication No. 2003-0060186, analog methods, and There is a method in which a digital method is mixed, and the present invention relates to an interference cancellation technique using a digital method.

Hereinafter, an example of an interference cancellation technique using a conventional digital method will be described with reference to FIG. 1.

The weight factor calculation unit 22 detects the received signal [R, R = S (original signal) + I (interference signal)] received through the reception antenna 11 at the front end of the subtractor 21, and transmit antenna 12 The output signal (^ S) transmitted through the C1 is detected at the front end of the transmitting antenna 12. The interference position is derived from the correlation between the received signal R and the output signal ^ S, and a weight factor (W) is calculated to remove the interference using the ICS algorithm.

Subsequently, the weight factor calculation unit 22 applies the calculated weight factor W to the adaptive filter 23, and the adaptive filter 23 generates the interference cancellation signal ^ I and then generates the interference cancellation signal ^. I) is input to the subtractor 21.

The subtractor 21 outputs a signal after interference cancellation by adding the interference cancellation signal ^ I input from the adaptive filter 23 to the reception signal R input from the reception antenna 11 side.

However, according to the technique of removing the interference signal from the received signal by the above method, in the adaptive signal processing method, the convergence period (time) for minimizing the signal after the interference cancellation is minimized when the algorithm initially converges or when the interference channel environment changes. need.

In addition, when proper isolation is not secured due to a change in the interval or channel for convergence, as shown in FIG. 2, a signal of a very high level (over power level) is output, thereby affecting the base station and the terminal. It may cause damage to the repeater itself due to the feedback of the transmission signal. Therefore, if the feedback signal (interference signal) due to overpower is input or the proper isolation cannot be obtained, it is necessary to limit the output gain or shut down the system. However, limiting the output gain inevitably reduces the service radius, and closing the system makes it impossible to stop the service.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and an object of the present invention is to provide a technique for limiting output within a limit of a set value when an output level of a signal from which interference is removed is greater than a set value.

In order to achieve the above object, there is provided an interference cancellation method of a wireless repeater for mobile communication with an overpower protection function according to an embodiment of the present invention, an output signal being received from a reception antenna side (a signal from a reception antenna side) and a transmission antenna side. A signal detecting step of detecting a signal (a signal output to the transmitting antenna side); A weight factor calculation step of calculating a weight factor based on a correlation between the received signal and the output signal detected in the signal detection step; An interference cancellation signal generation step of generating an interference cancellation signal according to the weight factor calculated in the weight factor calculation step; A post-interference canceled signal generation step of generating a post-interference canceled signal by subtracting the interference canceled signal generated in the interference canceled signal generation step from the received signal mixed with the original signal and the interference signal; And outputting the signal to the transmission antenna at a set value when the interference cancellation signal generated in the signal generation step after the interference cancellation is greater than or equal to a reference level, and passing the signal to the transmission antenna when the signal after interference cancellation is less than the reference level. step; Characterized in that it comprises a.

The weighting factor calculation step may further include calculating the weighting factor based on a correlation between the post-interference elimination signal and the output signal using the post-interference elimination signal as the reception signal.

In the weighting factor calculation step, the weighting factor is characterized in that it is calculated by an ICS algorithm.

The output signal in the weighting factor calculation step may be an interference elimination reference signal Ref that compensates for a delay occurring in its own circuit after the detected point.

In addition, the interference canceling device of the wireless repeater for mobile communication with the overpower protection function according to the present invention, the output signal is output to the reception signal and the transmission antenna side mixed with the original signal (S) and the interference signal (I) coming from the receiving antenna side A weight factor calculator for detecting a signal in real time and calculating a weight factor (W) through a correlation between the received signal and an output signal; An interference cancellation signal generation unit generating an interference cancellation signal (^ I) by applying the weight factor calculated by the weight factor calculation unit; A subtraction unit configured to subtract the interference cancellation signal (^ I) generated by the interference cancellation signal generation unit from the received signal to generate a signal after interference cancellation (Err) and output the signal to the transmission antenna side; And an over-power limiting unit for outputting the signal after the interference cancellation signal generated by the subtraction unit to the transmission antenna side at a set value, and passing the signal to the transmission antenna side when the generated interference cancellation signal is less than the reference level. Characterized in that it comprises a.

The interference elimination apparatus may further include a delay compensator configured to compensate the detected delay of the output signal and provide the weight factor calculation unit.

The weight factor calculation unit may calculate a weight factor W based on a correlation between the subtraction removal signal and the output signal using the after subtraction removal signal generated by the subtraction unit as the reception signal.

The interference cancellation signal generation unit may be an adaptive filter.

The over output limiting unit includes: comparing means for comparing a level of an input signal with a set value; Bypass means for bypassing the input signal; Setting value output means for outputting a signal having a set value; And when the level of the input signal is above or below a set value by the comparing means, sends a signal output from the set value output means to an output side, and if the level of the input signal is within a range of a set value by the comparing means. Switching means for switching to send a signal bypassed from the bypass means to an output side; It includes a more specific feature to include.

In addition, the present invention includes a mobile communication wireless repeater to which the above-described interference cancellation method or interference cancellation apparatus is applied.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention as described above will be described in detail.

Figure 3 is a perspective view of the main portion of the wireless repeater for mobile communication to which the interference cancellation device 300 according to an embodiment of the present invention is applied.

As shown in FIG. 3, the interference canceling apparatus 300 according to the exemplary embodiment of the present invention includes a subtraction unit 31, a weight factor calculation unit 32, an interference cancellation signal generation unit 33, and a delay correction unit 34. And an over power limiter 35 and the like.

The subtraction unit 31 generates the interference cancellation signal generation unit 33 from the reception signals R and R = S + I in which the original signal S and the interference signal I received through the reception antenna 11 are mixed. The interference elimination signal (^ I) inputted from the signal is generated and outputted after the interference elimination signal (Err).

The weight factor calculation unit 32 detects the interference canceled signal Err generated and output from the subtraction unit 31 and the output signal ^ S output through the transmission antenna 12 in real time, and then uses the ICS algorithm. The weight factor is calculated by the correlation between the signal Err and the output signal ^ S after the subtraction is removed. Herein, the output signal (^ S) detected by the weight factor calculation unit 32 is an interference cancellation reference signal Ref whose delay is corrected through the delay compensator 34 as described later.

The interference cancellation signal generation unit 33 is provided as an adaptive filter, and generates the interference cancellation signal ^ I in real time by applying the weight factor W calculated by the weight factor calculation unit 32. It is provided to the subtraction part 31.

The delay compensator 34 corrects the delay of the output signal ^ S detected on the transmission path. The delay compensator 34 compensates for the delay occurring in its own circuit after the point at which the output signal ^ S is detected, and as much as the delay of the output signal ^ S [interference signal of code I] which is ultimately fed back. In order to be compensated for, the interference cancellation reference signal Ref whose delay is compensated for in the output signal ^ S is provided to the interference cancellation signal generation unit 33 and the weight factor calculation unit 32.

The over output limiter 35 is provided at the rear end of the subtractor 31, and outputs the set value when the signal after the interference cancellation signal Err output from the subtractor 31 has an output level larger than the set value, and after the interference cancellation. If the signal Err is smaller than the set value, it is passed as it is.

As shown in FIG. 4, the overpower limiter 35 includes a comparison means 35a, a bypass means 35b, a set value output means 35c, a switching means 35d, and the like. The switching means 35d serves to selectively connect the output circuits from which the signal is output from the bypass means 35b or the set value output means 35c to the output side.

The comparison means 35a includes an upper limit level comparison logic 35a1 for comparing the upper limit of the signal and a lower limit level comparison logic 35a2 for comparing the lower limit of the signal.

According to the overpower limiter 35, the signal input to the overpower limiter 35 is input to the upper limit level comparison logic 35a1, the lower limit level comparison logic 35a2 and the bypass means 35b, and the upper limit level. When the signal input from the comparison logic 35a1 and the lower limit level comparison logic 35a2 is compared with the upper limit setting value and the lower limit setting value to confirm whether it is an over output, the switching means 35d performs a switching operation.

That is, when the input signal exceeds or falls below the upper limit set value, the set value output means 35c outputs a signal according to the set upper limit value or the lower limit set value, and the switching means 35d includes the set value output means 35c. The output circuit of is connected to the output side.

If the input signal is within the upper limit set value and the lower limit set value, the switching means 35d connects the output circuit of the bypass means 35b with the output side.

For reference, as shown in FIG. 4, the set value output unit 35d is divided into a part A for outputting an upper limit value and a part B for outputting a lower limit value, based on the power level 0. In this case, the switching means 35d may selectively output one of a portion A for outputting an upper limit value, a portion B for outputting a lower limit value, and an output circuit of the bypass means 35b. Is connected to the output side.

For reference, the reference numeral 20 filter acts as a correlation element for increasing the correlation between the signal Err and the output signal ^ S, which are detected in real time from both ends of the filter in the weight factor calculation unit 32.

The interference cancellation method performed by the interference cancellation apparatus 300 configured as described above will be described with reference to the flowchart of FIG.

1.Signal Detection <S401>

After the interference elimination signal Err and the output signal? S are detected in real time at the rear end of the subtractor 31 and the front end of the transmission antenna 12, respectively.

2. Delay Compensation <S402>

The delay compensator 34 compensates for the delay of the output signal ^ S detected at the front end of the transmission antenna 12 to generate the reference signal Ref for interference cancellation. The generated interference elimination reference signal Ref is provided to the weight factor calculator 32 and the interference elimination signal generator 33.

3. Weight factor calculation <S403>

The weight factor calculation unit 32 detects the signal after the interference elimination signal Err detected at the rear end of the subtractor 31 and the front end of the transmission antenna 12 by using the ICS algorithm, and then delays the signal by the delay compensation unit 34. The weight factor W is calculated through the correlation of the corrected interference cancellation reference signal Ref.

4. Interference cancellation signal generation <S404>

The interference cancellation signal generator 33 generates an interference cancellation signal by applying the weight factor W calculated by the weight factor calculator 32 to the interference cancellation reference signal Ref input from the delay compensator 34. do. In this way, the interference cancellation signal ^ I generated by the interference cancellation signal generator 33 is input to the subtractor 31.

5. Signal generation after interference cancellation <S405>

The subtractor 31 removes the interference from the reception signal R by subtracting the interference cancellation signal ^ I input from the interference cancellation signal generation unit 33 from the reception signal R received through the reception antenna 11. Generates and outputs the post signal (Err).

The post-interference elimination signal Err generated in step S405 is output to the transmission antenna 12, and the post-interference elimination signal Err is detected in real time as described in step S401.

That is, as described above, the interference cancellation signal generation unit 32 is a signal correlated with the interference cancellation reference signal Ref used in the ICS algorithm among the reception signal R components received through the reception antenna 11. The interference signal I is removed from the received signal R because the interference signal I has a correlation with the interference cancellation reference signal Ref. Since the original signal S has no correlation with the interference elimination reference signal Err, the original signal S is passed without being removed by the subtractor 31 and is sent to the transmission antenna 12 through the filter 30 or the like.

6. Over Power Limit <S406>

Meanwhile, in the signal generation step after the interference cancellation, the interference cancellation signal Err outputted from the subtractor 31 to the transmission antenna 12 is input to the over output limiting unit 35 provided at the rear end of the subtractor 31. If the signal after the interference elimination signal has an output level above or below the upper limit or lower limit, the over output limiter 35 outputs the set value by limiting the upper or lower limit setting value, and sets the upper and lower limit setting ranges. If it is within, it is output as it is. That is, as shown in FIG. 6, the over-outputted portion is limited to the set value and outputted.

As described above, the detailed description of the present invention has been made by the embodiments with reference to the accompanying drawings. However, since the above-described embodiments have only been described with reference to preferred examples of the present invention, the present invention is limited to the above embodiments. It should not be understood that the scope of the present invention is to be understood by the claims and equivalent concepts described below.

As described in detail above, the present invention has the following effects.

First, output of a large signal to a base station or a terminal is prevented at the source, thereby ensuring stability in field operation.

Second, since the interference canceling signal output from the subtractor is processed in real time, it can protect the equipment from instantaneous oscillation or abnormal input and also protect the receiving end of the base station from the instantaneous oscillation. Can be.

Claims (11)

A signal detecting step of detecting a reception signal (a signal from the reception antenna side) coming from the reception antenna side and an output signal (signal output to the transmission antenna side) output to the transmission antenna side; A weight factor calculation step of calculating a weight factor based on a correlation between the received signal and the output signal detected in the signal detection step; An interference cancellation signal generation step of generating an interference cancellation signal according to the weight factor calculated in the weight factor calculation step; A post-interference canceled signal generation step of generating a post-interference canceled signal by subtracting the interference canceled signal generated in the interference canceled signal generation step from the received signal mixed with the original signal and the interference signal; And If the interference canceled signal generated in the signal generation step after the interference cancellation is greater than or equal to the reference level, and outputs to the transmission antenna side with a set value, and if the generated interference cancellation signal is less than the reference level, the over-output limit step ; Method of eliminating interference of a wireless repeater for mobile communication with an over-output protection, characterized in that it comprises a. The method of claim 1, In the weighting factor calculation step, the weighting factor is calculated based on a correlation between the interference elimination signal and the output signal using the interference elimination signal as the reception signal. Method of eliminating interference of wireless repeater. delete The method of claim 1, The output signal in the weighting factor calculation step is an interference cancellation reference signal (Ref) for compensating for the delay occurring in its own circuit after the detected point. Way. Real-time detection of the output signal output to the transmission antenna and the reception signal mixed with the original signal (S) and the interference signal (I) coming from the receiving antenna side and weighting factor (W) through the correlation between the received signal and the output signal A weighting factor calculator for calculating; An interference cancellation signal generation unit generating an interference cancellation signal (^ I) by applying the weight factor calculated by the weight factor calculation unit; A subtraction unit configured to subtract the interference cancellation signal (^ I) generated by the interference cancellation signal generation unit from the received signal to generate a signal after interference cancellation (Err) and output the signal to the transmission antenna side; And An overpower limiter for outputting the signal after the interference cancellation signal generated by the subtractor to the transmission antenna at a set value, and passing the signal to the transmission antenna when the generated interference cancellation signal is less than the reference level; Interference elimination device of the wireless repeater with over output protection, characterized in that it comprises a. The method of claim 5, And a delay compensator for compensating for the detected delay of the output signal to the weighting factor calculator. The method of claim 5, The weight factor calculating unit calculates a weight factor (W) based on a correlation between the subtracted removing signal and an output signal using the subtracted removing signal generated by the subtracting unit as the received signal. Interference elimination device of the wireless repeater. The method of claim 5, And said interference cancellation signal generator is an adaptive filter. The method of claim 5, The overpower limiting unit, Comparison means for comparing the level of the input signal with a set value; Bypass means for bypassing the input signal; Setting value output means for outputting a signal having a set value; And If the level of the input signal is above or below the set value by the comparing means, the signal output from the set value output means is sent to the output side, and if the level of the input signal is within the range of the set value by the comparing means, Switching means for switching to send a signal bypassed from the bypass means to an output side; Interference elimination device of the wireless repeater with over output protection, characterized in that it comprises a. delete A wireless repeater having an overpower protection function to which the interference canceling device according to any one of claims 5 to 9 is applied.

Images