KR20110040201A - Method for auto gain compensation to interference cancellation repeater - Google Patents

Abstract

PURPOSE: An automatic gain compensation method of an interference cancellation relay is provided to regularly maintain the gain of a system through an AGC mode and to automatically reduce gain about an interference signal. CONSTITUTION: An interference processing unit of an interference cancellation relay measures the power level of an input signal(S10). If a measured power level is greater than a reference power level, the interference cancellation relay automatically reduces the gain G of an amplifier to a predetermined set value(S20, S30). If the size of the interference reduces, the interference cancellation relay eliminates the interference of an input signal(S40).

Description

Method for auto gain compensation to interference cancellation repeater

The present invention relates to a wireless repeater in a mobile communication system. In particular, in order to improve the performance of an interference canceling repeater, an interference canceling repeater signal processor automatically reduces the gain of an interference signal and naturally reduces the gain of the interference canceled signal. The present invention relates to an automatic gain compensation method of an interference cancellation repeater.

Mobile communication systems can be roughly classified into mobile communication exchanges, base stations (including repeaters), and mobile stations.

The mobile communication exchange is composed of connection with each base station control device, information and authentication for subscribers, and related additional equipment, and plays a role of making a connection with other networks. The base station is composed of a base station control device (BSC), a base station, etc., for the purpose of connection with the exchange so that the mobile station can make a call with the desired counterpart.

With regard to mobile communication quality of service, the location of the base station and the number of base stations are very important factors. Therefore, although it is ideal to increase the number of base stations to improve the quality of service, considering that it takes considerable facility cost to install the base stations, the method of improving the communication service quality while installing as few base stations as possible, that is, repeater The technique used is presented.

The repeater transmits a radio frequency signal of the base station to a desired remote area through a third transmission medium and reproduces the RF signal again. The repeater does not increase the call channel, but can sufficiently replace the base station in terms of extension of communication service coverage. The mobile communication service provider may place a base station in a cell dense area when designing a base station match and may install a repeater in an area other than the dense area.

The repeaters currently used in mobile communication are roughly classified into optical repeaters that are connected between base stations and repeaters by optical cables and wireless repeaters that are wirelessly connected. The optical repeater converts the RF signal of the base station into an optical signal, transmits it to a desired remote area along the optical path, and then converts the RF signal into an RF signal and transmits it to an antenna via a high power amplifier (HPA). Since the optical repeater is wired between the base station and the repeater, it is possible to maintain good call quality, but it is more expensive than the wireless repeater, in particular, the cost of installing or renting an optical cable is considerably expensive.

On the other hand, the wireless repeater has a lower call quality than the wired repeater of the optical repeater, but has the advantage that the installation or operation cost is lower.

Wireless repeaters can be particularly useful for providing communication services in buildings. In underground spaces such as the underground parking lot of a large building, since the electromagnetic wave is shielded by the structure and the coverage of one repeater is inevitably small, it is preferable to use a wireless repeater which costs less than an expensive optical repeater. .

1 is a schematic diagram illustrating a mobile communication relay system in which a plurality of base station signals are received by a wireless repeater and relayed to a user terminal in a wireless communication environment.

As illustrated in FIG. 1, in the mobile communication relay system, a wireless repeater 10 is wirelessly connected to a plurality of mobile communication base stations 20. In addition, the wireless repeater 10 is wirelessly connected to the mobile station (user terminal: 40).

In the case of the forward link, the wireless repeater 10 receives signals 40 and 50 transmitted from the mobile communication base station 20 through the wireless path by using the base station antenna of the wireless repeater 10. After amplifying the transmission signals 40 and 50 in the repeater 10, the signals are transmitted to the mobile station 30 using the coverage antenna of the wireless repeater 10.

2 is a schematic diagram of a wireless repeater according to the prior art.

As shown in FIG. 2, the wireless repeater 10 receives a signal received from the mobile communication base station 20 or another repeater at the receiver 11, and the received transmission signal is transmitted to the amplifier 12 to a signal having a desired size. Is amplified. The signal amplified by the amplifier 12 is transmitted to the transmitter 13, and is transmitted from the transmitter 13 to the mobile station 30 via a wireless path.

In this case, when the wireless repeater 10 is used in an open area rather than an area inside the building, the mobile station 30 amplifies a signal of various paths received from many mobile communication base stations or repeaters and transmits the signal. Even if the received signal strength is large, many of the signal components include unwanted interference signals. In particular, when the output signal of the wireless repeater 10 is reflected on the building or the terrain / feature, the output signal is fed back (B-t-d) and enters the input of the wireless repeater 10 again. This signal B (t-d) is combined with the normal signal A (t) coming from the mobile communication base station 20 to operate by interference. When the normal signal A (t) and the feedback signal B (td) are combined, the signal is amplified by the wireless repeater 10 and the signal is fed back to the wireless repeater 10 to be inputted to the wireless repeater 10. Oscillation occurs with excessively increased output power.

Due to this problem, the wireless repeater operates with a gain smaller than the gain that can actually be amplified, and there are many restrictions in operation such as the use of a large distance between antennas.

In order to overcome the problems of the existing wireless repeater, an interference cancellation repeater has been developed and commercialized.

As shown in FIG. 3, the interference elimination repeater 100 is fed back from the signal A (t) received by the interference elimination repeater 100 using the interference elimination processing unit 110 and inputs the signal component B (td). Is reproduced and subtracted from the received signal A (t) + B (td) to recover the original received signal A (t).

The interference cancellation processing unit 110 has various schemes, and most of the schemes use adaptive algorithms, and the indicators indicating the performances of the interference schemes are as follows.

Figure 4 is a schematic diagram for explaining the concept of the interference cancellation repeater according to the prior art.

As shown in FIG. 4, when the signal A (t) received from the mobile communication base station 20 is input through the receiving antenna 130, the interference canceling repeater 100 receives the amplification unit 120. Amplified by the gain G, and output through the transmit antenna 140.

Since the interval between the transmitting antenna 140 and the receiving antenna 130 is the shortest feedback path in the interference elimination repeater 100, the output signal of the repeater is returned first. That is, since the transmitting antenna 303 and the receiving antenna 302 are separated from each other by about 1 to 3 m, a path through which the signal G * A (t) output through the transmitting antenna 303 enters the fastest signal level is fastest. Becomes This signal thus becomes the largest interfering signal. This is referred to as separation 150.

If the separation degree 150 has a very large value, the fed back signal B (t-d) = G * A (t) -Iso has a very small value. Therefore, since the amount of interference fed back is small, the interference cancellation repeater 100 can effectively remove the interference.

However, if the separation degree 150 is small, the feedback signal B (t-d) becomes large, and therefore, the size of the interference signal becomes large, making it impossible to completely remove the interference from the interference cancellation repeater. In this case, there is a problem that the interference cancellation repeater also oscillates like a conventional wireless repeater.

Here, comparing the performance of the interference elimination repeater and the general wireless repeater can be defined as follows.

The wireless repeater 10 having no interference cancellation function may prevent oscillation only when the gain G of the amplifier 12 is 15 dB or more higher than the separation degree 150. That is, if the separation 150 is 100dB, the wireless repeater 10 should have a gain G of 85dB or less.

On the other hand, the interference elimination repeater 100 may prevent oscillation while removing interference even if the gain G of the amplifier 120 is higher than the separation degree 150. In the currently implemented technology, even if the gain G of the amplifier 120 is 20 dB higher than the separation degree 150, interference can be prevented and oscillation can be prevented. That is, if the isolation 150 is 100 dB, the interference cancellation repeater 120 may have a gain of 120 dB.

Based on the description so far, the wireless repeater 10 has a performance of 85 dB in the condition that the separation 150 is 100 dB, but the interference canceling repeater 100 may have a gain of 120 dB, and thus the overall performance is improved by 35 dB. have.

However, the interference elimination repeater 100 also cannot avoid oscillation if the separation degree is deteriorated to 99dB in a situation where the gain of the amplifier 120 is 120dB. In other words, if the separation is reduced according to the change of the external environment in the condition that the interference elimination repeater 100 operates with the maximum gain, the interference elimination repeater 100 also oscillates.

Therefore, the present invention has been made to solve the above problems, and through the stop & go method to temporarily stop the operation of the interference cancellation processing unit to prevent divergence of the interference cancellation algorithm and gradually return to the original gain The purpose of the present invention is to provide an automatic gain compensation method of an interference cancellation repeater that improves the performance of an interference cancellation repeater.

Another object of the present invention is to provide an automatic gain compensation method of an efficient interference canceling repeater which can improve the performance of the interference canceling repeater by 3 to 5 dB compared to the existing system while maintaining a constant gain of the overall system.

It is still another object of the present invention to provide an interference canceling repeater, in order to further improve its performance, an interference canceling repeater signal processing unit may automatically reduce a gain for an interference signal and automatically increase a gain of an interference canceled signal. An automatic gain compensation method of the eliminating repeater is provided.

It is still another object of the present invention to provide an automatic gain compensation method of an interference cancellation repeater capable of expanding a coverage area serviced by a wireless repeater by improving the quality of a signal transmitted from an interference cancellation repeater to a terminal.

A feature of the automatic gain compensation method of the interference canceling repeater according to the present invention for achieving the above object is the interference configured to include amplification unit and the interference cancellation processing inside the wirelessly connected to each of a plurality of mobile communication base stations and mobile stations A gain compensation method of a removing repeater, the method comprising: measuring a power level of a wirelessly input signal, comparing the measured power level with a preset reference power level, and if the measured power level is equal to or greater than a reference power level, Changing the second gain g to a value smaller than the first gain G of the amplifying unit configured inside the interference elimination repeater, and interfering with a signal input using the interference elimination processing unit configured in the interference eliminating repeater. And removing the interference gain while constantly increasing the changed second gain g to the first gain G. It may comprises a step of feeding back the interference canceled signal via a processing unit.

Preferably comparing the second gain (g) of the amplifying unit and the first gain (G) of the amplifying unit which rises to the predetermined value, and the second gain (g) is returned to the first gain (G) as a result of the comparison If so, further comprising the step of stopping the operation of the interference cancellation processing unit.

Preferably, the first gain G of the amplifying unit has a value of 20 dB or less than the separation degree.

The automatic gain compensation method of the interference cancellation repeater according to the present invention as described above has the following effects.

First, the automatic gain control method can improve the performance of the interference elimination repeater by 3 ~ 5dB compared to the existing system while maintaining the gain of the overall system.

Second, through the Stop & Go method, the gain of the interference signal is automatically reduced, and the gain of the interference canceled signal is automatically raised to more effectively improve the performance of the interference cancellation repeater.

Third, another object of the present invention is to improve the quality of the signal transmitted from the interference elimination repeater to the terminal, thereby extending the coverage area serviced by the wireless repeater.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments with reference to the accompanying drawings.

A preferred embodiment of the automatic gain compensation method of the interference canceling repeater according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be embodied in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations. In addition, the same reference numerals as FIGS. 1 to 4 refer to the same member performing the same function.

5 is a flowchart illustrating an automatic gain compensation method of an interference cancellation repeater.

Referring to FIG. 5, first, a power level of a signal input from the interference processor 110 of the interference elimination repeater 100 is measured (S10), and the measured power level is compared with a preset reference power level (S20). ). In this case, the reference power level refers to a power level in which oscillation occurs or a risk of oscillation occurs due to a signal (separation degree) having excessive interference in which the interference elimination repeater 100 can no longer remove interference.

As a result of the comparison (S20), when the measured power level is equal to or higher than the reference power level, it is determined that oscillation will occur, and the gain G of the amplifier 120 configured inside the interference elimination repeater 100 is automatically set to a gain g which is a preset value. Reduce to (S30). In this case, if the gain G of the amplifier 120 is reduced to the gain g, the signal B (td) fed back is also reduced, so that the amount of interference of the fed back input signal is reduced, so that the level of the input signal is lowered. Can prevent rashes. For reference, the gain G of the amplifier is preferably 20 dB or less than the separation degree.

When the size of the interference is reduced by reducing the gain G of the amplification unit 120 to the gain g, the interference cancellation processing unit 110 can sufficiently remove the interference, and thus the interference reduction processing unit 110 reduces the interference. The interference of the input signal is removed (S40). At this time, the method for removing interference through the interference cancellation processing unit 110 is a well-known technique and detailed description thereof will be omitted.

Subsequently, the interference elimination repeater 100 removes the reduced interference by using the interference elimination processing unit 110 and then gradually raises the gain g of the amplification unit 120 at a constant gradually (S50) (S60). In step S70, the interference-reduced signal is fed back and combined with the input signal A (t) received from the mobile communication base station 20. At this time, i and a shown in the drawing are constants for gradually raising the gain g of the amplifier 120 constantly. This is a value that is arbitrarily set according to the designer, it will be understood that various constants are possible.

Then, the gain g of the amplifying unit gradually rising to the constant value and the original gain G of the amplifying unit 120 are continuously compared (S80), and the comparison result (S80), the gain g of the amplifying unit 120 is the original amplifying unit. When returning to the gain G of 120, the operation of the interference cancellation processing unit 110 is stopped in the returning process (S90).

As such, the conventional interference elimination repeater reduces the gain of the amplifier 120, and immediately stops the interference elimination processing unit 110. In this case, the conventional interference elimination repeater makes the separation degree 150 worse. When the amount of interference fed back is increased, the oscillation can be prevented by reducing the gain G of the amplifier 120.

However, when such an operation is performed, the gain G of the amplification unit 120 is reduced, resulting in a problem that the sound coverage of the interference elimination repeater 100 is reduced. That is, the conventional interference elimination repeater is designed to prevent the oscillation once by reducing the gain G and increase the gain once the separation degree 150 is improved, so that the conventional interference elimination repeater operates with the maximum gain. If the separation degree 150 is reduced according to the change of the external environment, the coverage of the interference elimination repeater 100 becomes unstable and causes oscillation.

Therefore, in the present invention, after the interference elimination repeater 100 removes the reduced interference by using the interference elimination processing unit 110 and gradually returns to the original gain while gradually raising the gain g of the amplifier 120 constantly. In addition, the performance of the interference cancellation repeater 110 is improved, and the operation of the interference cancellation processing unit 110 is not stopped at a time when the gain G of the amplifier 120 is reduced, but the gain g of the reduced amplifier 120 is reduced. Stops the operation of the interference cancellation processing unit 110 at the time point of returning to the original amplifier gain G, thereby solving the problem that the coverage of the interference cancellation repeater 100 is shaken due to existing environmental factors.

In this way, the interference cancellation repeater 100 is fed back through the stop & go method that stops the operation of the interference cancellation processing unit 110 at the time of returning to the original gain G, while feedback is worsened. Even if the amount of interference increases, oscillation can be prevented, and the performance can be improved by about 3 to 5 dB compared to the conventional interference cancellation repeater.

Although the technical spirit of the present invention described above has been described in detail in a preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a schematic diagram showing a mobile communication relay system according to the prior art;

2 is a schematic schematic view of a wireless repeater according to the prior art;

Figure 3 is a schematic diagram for explaining the concept of a wireless repeater according to the prior art

Figure 4 is a schematic diagram for explaining the concept of the interference cancellation repeater according to the prior art

5 is a flowchart illustrating an automatic gain compensation method of an interference cancellation repeater.

DESCRIPTION OF THE REFERENCE NUMERALS

10: wireless repeater 11: receiver

12 amplifier unit 13 transmitter unit

20: mobile communication base station 30: mobile station (user terminal)

100: interference elimination repeater 110: interference elimination processing unit

120: amplifier 130: receiving antenna

140: transmitting antenna 150: separation

Claims (4)

In the gain compensation method of the interference canceling repeater which is connected to a plurality of mobile communication base stations and mobile stations, respectively, wirelessly and comprises an amplifier and an interference cancellation processing unit therein, Measuring a power level of a signal input wirelessly, comparing the measured power level with a preset reference power level, If the measured power level is equal to or greater than the reference power level, changing the second gain g to a value smaller than the first gain G of the amplifier configured inside the interference elimination repeater; Removing interference of an input signal by using an interference cancellation processor configured inside the interference cancellation repeater; And feeding back the signal from which the interference has been canceled through the interference cancellation processing unit while raising the modified second gain (g) to the first gain (G) constantly. . The method of claim 1, The reference power level is the automatic gain compensation method of the interference cancellation repeater, characterized in that the oscillation occurs due to excessive interference that the interference cancellation repeater (100) can no longer remove the interference. The method of claim 1, Comparing the second gain g of the amplifying unit and the first gain G of the amplifying unit to rise to the constant value; And stopping the operation of the interference cancellation processing unit when the second gain g returns to the first gain G as a result of the comparison. The method according to claim 1 or 3, The first gain (G) of the amplification unit has a value of 20dB or less than the separation degree automatic gain compensation method of the interference cancellation repeater.

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