KR20020076961A - A method for detecting oscillation using the output variation of a rf repeater and a rf repeater adapting said method - Google Patents

Abstract

PURPOSE: A method of sensing oscillation is provided to change a gain of a repeater when oscillation is rapidly changed, and to compare the changed gain with a changed output value, to sense the oscillation, thereby preventing a bad influence on a base station. CONSTITUTION: A CPU senses an output(Lo1) of a repeater, and checks whether the output(Lo1) of the first repeater is higher than an automated control level(Lref)(S2-S4). If so, the CPU lowers a gain(Grf) of the repeater to control the repeater gain(S6). The CPU re-senses an output(Lo2) of the repeater, and checks whether a difference(L01-Lo2) of the first repeater output(Lo1) and the second repeater output(Lo2) is bigger than a repeater output difference with a normal signal(S8-S10). If so, the CPU decides an oscillation of the repeater(S16).

Description

Oscillation detection method using output variation of RF repeater and RF repeater employing the same {A METHOD FOR DETECTING OSCILLATION USING THE OUTPUT VARIATION OF A RF REPEATER AND A RF REPEATER ADAPTING SAID METHOD}

The present invention relates to an oscillation detection method using an output change amount of an RF repeater and an RF repeater employing the same, in particular, to accurately detect the oscillation in the repeater to stop the operation when the repeater is oscillated to prevent adverse effects on the base station The present invention relates to a method for detecting oscillation by comparing gain variation and output variation of a repeater.

In general, in a mobile communication service system, a base station and a mobile station communicate in a constant frequency band, and each base station has a constant call radius. Therefore, by arranging a plurality of base stations appropriately so that the call radius of each base station overlaps with each other, it is possible to widen the callable area.

However, even if such a plurality of base stations are arranged to cover the entire city, a call shadow area is generated which is not available in the underground space of a large building and the inside of a high-rise building.

Due to the occurrence of the call shaded area, mobile phone users cannot receive smooth call service within the call shaded area. To solve the problem of occurrence of the call shaded area, a repeater is installed in the shaded area. In addition, the repeater can eliminate the shadow area at a lower cost than the base station.

In general, several or several dozens of such repeaters are connected to one base station, and as the number of repeaters connected is increased, the amount of noise reversely introduced into the base station increases in proportion, resulting in a decrease in capacity of the base station. In particular, oscillation may occur in the repeater itself according to the installation location or situation, and reverse oscillation has a problem of causing a fatal defect in the reception path of the base station to which the repeater is connected. In other words, when such oscillation occurs, the signal from the mobile station acts as a noise, so the call cannot be set up normally between the repeater and the mobile station, and in this case, an increase in the load on the base station can be caused. In addition, in the case of the reverse link, the noise level of the base station may be increased by increasing the noise level due to oscillation, which may adversely affect the capacity or quality of the corresponding area in a cell served by the base station.

Therefore, in the repeater, the oscillation (especially reverse oscillation) phenomenon is detected, and when the reverse oscillation phenomenon is detected, the oscillation prevention function such as blocking the reverse output to prevent base station capacity reduction and protecting the reception path should be performed.

4 is a graph showing the relationship between the general oscillation progress and the output, and FIG. 5 is a graph showing an ideal oscillation detection and output interruption operation. That is, as shown in FIG. 4, when there is no oscillation detection and output interruption operation, the output continues even when the output level reaches a maximum value (100%), but in the case of a repeater having an ideal oscillation detection and output interruption operation, If the output level is 70% or more of the maximum value (approximately 28dBm), the oscillation is judged to cut off the output.

On the other hand, as a method for detecting and preventing the reverse oscillation as described above, there was an oscillation detection method of comparing the output level, which will be described with reference to FIG.

6 is a graph showing the relationship between automatic level adjustment and oscillation detection in the RF repeater of FIG.

The RF input is RF output via the first RF unit 6 and the second RF unit 7, and a gain adjuster 4 is positioned between the first and second RF units. In addition, the RF output is detected as a voltage by the output sensing unit 1, and a voltage corresponding to the output level sensed by the output sensing unit is a signal input of the automatic level voltage comparator T1 and the oscillation level voltage comparator T2. Becomes The reference voltage of the automatic level voltage comparator T1 becomes the divided voltage of the variable resistor of the automatic level setter 2, and the reference voltage of the oscillation level voltage comparator T2 is the variable resistor of the oscillation level setter 3. The divided voltage becomes. Reference numerals C1, C2, C3 and C4 are capacitors for coupling to bypass.

If the detected voltage corresponding to the output level is larger than the reference voltage of the automatic level setter 2 (that is, if the output level is more than 60% (about 23 dBm) of the maximum value) (see Fig. 6), the automatic level voltage comparator T1 ) Output is 'high', causing the gain regulator 4 to lower the repeater gain to adjust the output.

In addition, if the detected voltage corresponding to the output level is larger than the reference voltage of the oscillation level setter 3 (that is, if the output level is 70% or more (about 28 dBm) or more of the maximum value) (see Fig. 6), the oscillation level voltage comparator ( Since the output of T2) becomes 'high' and a 'high' signal is applied to the input terminal LI1 of the CPU 5, the central processing unit 5 controls the output of the output terminal LO1. The signal is 'high' and the operation of the first and second RF units 6 and 7 is stopped.

However, in this conventional system, as shown in Fig. 6, even when the oscillation phenomenon is in progress, the output level does not reach the magnitude of the oscillation detection level by the automatic level control function, and thus the output cannot be blocked in a timely manner. May occur. Although in this case, the output does not reach the oscillation detection level, but the output of the level close to it continues, the wireless environment at this time has a difficult problem that has a fatal adverse effect on the base station operating the frequency.

In order to solve this problem, conventionally, by using only the oscillation detection unit of the output level comparison method without using the automatic level control function, a method of avoiding the harmful effects of the base station while giving up the automatic level control function It was also chosen. However, if the repeater is operated without the automatic level control function, if the repeater input is excessively input, the output of the repeater becomes too high and the output stage amplifier saturates and radiates unnecessary noise toward the base station. Another problem is that it degrades the call quality.

The present invention is to solve the above problems, an object of the present invention, while the repeater has an automatic level control function and accurately detects the oscillation to detect the oscillation using the output change amount of the RF repeater to cut off the output in a timely manner It is to provide a method and an RF repeater employing the same. Accordingly, the present invention provides a method of detecting whether the repeater is oscillated by changing the gain at the time when the oscillation rapidly develops and comparing the output variation according to the gain change.

Further objects and effects of the present invention will become more apparent from the following detailed description of the invention described with reference to the accompanying drawings.

1 is a circuit diagram of an automatic level control circuit and an oscillation detection device of a conventional RF repeater.

2 is a circuit diagram of an RF repeater according to the present invention.

3 is a flowchart illustrating an oscillation detection method using an output change amount of an RF repeater according to the present invention.

4 is a graph showing the relationship between the general oscillation progress and the output.

5 is a graph showing an ideal oscillation detection and output interruption operation.

6 is a graph showing the relationship between automatic level adjustment and oscillation detection in the conventional RF repeater of FIG.

7 is a graph showing the relationship between the oscillation progress and the output according to the oscillation detection method of the RF repeater according to the present invention.

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

1: output detector 2: automatic level setter

3: oscillation level setter 4: gain adjuster

5: central processing unit (CPU) 6: first RF unit

7: second RF unit

The oscillation with output variation of the RF repeater in accordance with an aspect of the present invention for achieving the object, detection method, (a) by detecting the output (L _o1) of the repeater, said first repeater output (L _o1) The Checking whether it is higher than the automatic adjustment level (L _ref ) (S2-S4); (b) adjusting the repeater gain by lowering the repeater gain (G _rf ) when the first repeater output (L _o1 ) is higher than the automatic adjustment level (L _ref ) (S6); (c) After a predetermined time, when the output L _o2 of the repeater is sensed again, when the difference L _o1 -L _o2 between the first repeater output L _o1 and the second repeater output L _o2 is a normal signal. Checking whether the repeater output difference is greater than ΔG (S8-S10); And (d) determining the repeater oscillation when the number of times when the difference (L _o1 -L _o2 ) of the repeater outputs at the predetermined time interval is greater than the repeater output difference (ΔG) when the normal signal is greater than or equal to a predetermined value. It characterized in that it comprises a step (S16).

Preferably, the method comprises the steps of: (c ') counting a number of times greater than the repeater output difference (ΔG) when the difference (L _o1 -L _o2 ) of the repeater output is a normal signal before step (d) ( S12), wherein the step (d) repeats the steps (a) to (c ') when the count value is less than the predetermined number of times, and the repeater output (L _o1 ) is automatically adjusted. Until it is not higher than the level (L _ref ) or when the difference (L _o1 -L _o2 ) of the repeater output is not higher than the repeater output difference (ΔG) when it is a normal signal or the difference (L) of the repeater output _o1 -L _o2 ) is repeated until a case greater than the repeater output difference ΔG when a normal signal is found, and the repeater output L _o1 is not higher than the auto-adjustment level L _ref or the output Repeater output difference when the difference between L _{o1 and} L _o2 is a normal signal If it is not higher than (ΔG), it is determined that the oscillation is not oscillation, and the number of times when the repeater output difference (ΔG) when the difference (L _o1 -L _o2 ) of the repeater output is a normal signal is greater than or equal to the predetermined value. In this case, it is characterized by judging by the repeater oscillation.

Also preferably, in the step (d), even if the difference between the repeater outputs (L _o1 -L _o2 ) at the predetermined time interval is considerably larger than the repeater output difference (ΔG) when the normal signal is once. If present, it is characterized by judging by the repeater oscillation.

RF repeater employing the oscillation detection method using the output change amount of the RF repeater according to another aspect of the present invention, the central processing unit (5) for performing the oscillation detection method; An output sensing unit 1 sensing an output L _o1 of the repeater; A gain controller (4) in which the central processing unit adjusts gain in accordance with a control signal for adjusting the repeater gain; And at least one RF unit 6, 7 which is 'off' according to the output control signal when the central processing unit detects the oscillation state, thereby preventing the RF output to the base station during the oscillation operation. .

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

First, a repeater employing the oscillation detection method of the RF repeater according to the present invention will be described with reference to FIG. For the sake of simplicity, the same reference numerals are given to the parts having the same function as the conventional repeater of FIG. 1 and the detailed description thereof will be omitted.

As shown in Fig. 2, when the output level of the RF output is detected by the output sensing unit 1, this detection signal is directly input to the central processing unit 5 through the input terminal AD0 of the central processing unit 5. Becomes In addition, the output of the central processing unit 5, in addition to the first output terminal (LO1) for emitting control signals to the first and second RF unit (6, 7), the agent for emitting a control signal to the gain regulator (6) It has two output stage DA0. Therefore, the CPU 5 controls both the first and second RF units 6 and 7 and the gain regulator 4 by the output detection signal.

Hereinafter, the operation of the CPU 5 will be described in detail with reference to FIG. 3.

First, the bar to check whether nopeunga than the central processing unit 5, by detecting the output (L _o1) of the repeater (S2), the first relay output (L _o1) The automatic adjustment level (L _ref) (S4 Otherwise, the process is terminated, and if higher, the gain regulator control signal is output to the second output terminal DA0, thereby reducing the repeater gain G _rf to adjust the repeater gain (S6).

Thereafter, the output L _o2 of the repeater is sensed again (S8), and the repeater when the difference L _o1 -L _o2 between the first repeater output L _o1 and the second repeater output L _o2 is a normal signal. It is checked whether the output difference (that is, the gain difference: ΔG) is greater than (S10). If not, the process is terminated, and if it is higher, the difference (L _o1 -L _o2 ) of the repeater outputs measured at predetermined time intervals is counted more than the gain difference ΔG. That is, the count value from the first occurrence of this phenomenon is incremented (S12).

Then, it is checked whether or not the count value is equal to or greater than a predetermined value (two times in the embodiment of FIG. 7) (S14), and in such a case, it is determined as a repeater oscillation (S16). Therefore, by outputting a repeater output 'off' control signal to the first output terminal LO1 (S18), the operation of the first and second RF units 6 and 7 is temporarily suspended to prevent the RF output to the base station. . Thereafter, the count value is cleared (S20), and the process ends.

However, as a result of the determination in step S14, if the count value is less than the predetermined number of times (for example, two times), the process returns to step S2 to repeat the above procedure (S2-S14). As a result of the first and second output detection, when it is determined in step S4 that the first repeater output L _o1 is not higher than the automatic adjustment level L _ref , and in step S10, the first repeater output L _Even when it is determined that the difference (L _o1 -L _o2 ) between the second repeater output (L _o2 ) and the second repeater output (L _o2 ) is not greater than the repeater output difference (that is, the gain difference: ΔG), it is determined that the oscillation is not oscillation. If so, the previous count is cleared and the process ends.

As described above, the oscillation detection method using the change amount of the output of the RF repeater of the present invention performs oscillation detection using the comparison of the gain change amount and the output change amount for a predetermined time interval, when the oscillation phenomenon rapidly develops. The output increases rapidly at a moment, and the amount of change in output relative to the gain is significantly larger than the normal output (output without oscillation). When the change is detected and a sudden change indicative of such oscillation occurs continuously for a predetermined number of times or more, it is determined as oscillation. According to the RF repeater employing the oscillation detection method using the output change amount of the RF repeater of the present invention, as shown in FIG. Similarly, a graph approximating the ideal oscillation detection method and output cutoff graph of FIG. 5 can be obtained.

The present invention has been described above with reference to one embodiment shown in the accompanying drawings, but the present invention is not limited thereto. For example, the time will be a predetermined value of said first count value, but, in this case, the first repeater output (L _o1) and second relay output difference (L _o2) (L -L _{o1 o2)} in a normal signal Oscillations should be considered if they are significantly greater than the repeater output difference (i.e. gain difference ΔG).

That is, the present invention can be modified in various ways within the range that can be easily conceived by those skilled in the art. Therefore, the limitation of the present invention should be limited only by the following claims.

As described above, in the conventional method of detecting the oscillation level, the oscillation detection method using the output variation of the RF repeater according to the present invention has an adverse effect on the wireless environment due to the inability to detect oscillation under automatic level control. According to the RF repeater employing this method, the oscillator detects the oscillation by changing the gain of the repeater when the oscillation changes sharply and compares it with the output change value. It is not possible to solve the conventional problem that has a fatal adverse effect on the base station.

Claims (4)

(a) by detecting the output of the repeater (L _o1), the first relay output stage (S2-S4) to check whether nopeunga than (L _o1) automatically adjusting the level (L _ref) is; (b) adjusting the repeater gain by lowering the repeater gain (G _rf ) when the first repeater output (L _o1 ) is higher than the automatic adjustment level (L _ref ) (S6); (c) After a predetermined time, when the output L _o2 of the repeater is sensed again, when the difference L _o1 -L _o2 between the first repeater output L _o1 and the second repeater output L _o2 is a normal signal. Checking whether the repeater output difference is greater than ΔG (S8-S10); And (d) determining the repeater oscillation when the number of times when the difference (L _o1 -L _o2 ) between the repeater outputs at the predetermined time interval is greater than the repeater output difference (ΔG) when the normal signal is greater than or equal to a predetermined value; (S16) Oscillation detection method using the output change amount of the RF repeater comprising a. The method of claim 1, wherein the method is (c ') counting a number of times greater than the repeater output difference ΔG when the difference L _o1 -L _o2 of the repeater output is a normal signal before step (d), and In the step (d), if the count value is less than the predetermined number of times, the steps (a) to (c ') are repeated, but the repeater output L _o1 is not higher than the automatic adjustment level L _ref . If not, or when the difference between the repeater outputs (L _o1 -L _o2 ) is not higher than the repeater output difference (ΔG) when it is a normal signal or the difference between the repeater outputs (L _o1 -L _o2 ) is normal Repeat until a case is found that is greater than the repeater output difference ΔG for the signal, and the repeater output L _o1 is not higher than the auto-adjustment level L _ref or the difference of output L _o1 -L _{If o2} ) is not higher than the repeater output difference (ΔG) when the signal is normal, it is determined that the oscillation is not oscillation, and more than the repeater output difference (ΔG) when the difference (L _o1 -L _o2 ) of the repeater output is a normal signal. The number of times when large is less than the predetermined value If the method has detected oscillation with output variation of the RF repeater, characterized in that for determining a repeater oscillation. The method of claim 1, In the step (d), if there is a case where the difference (L _o1 -L _o2 ) between the repeater outputs at the predetermined time interval is significantly larger than the repeater output difference (ΔG) when the normal signal exists, An oscillation detection method using an output change amount of the RF repeater, characterized in that the oscillation is determined. A central processing unit (5) for performing the method of any one of claims 1 to 3; An output sensing unit 1 sensing an output L _o1 of the repeater; A gain controller (4) in which the central processing unit adjusts gain in accordance with a control signal for adjusting the repeater gain; And When the central processing unit detects the oscillation state by including at least one RF unit (6, 7) 'off' according to the output control signal, RF repeater that adopts the function to block the RF output to the base station during oscillation operation.