KR100981242B1 - Repeater system for dividing signal in multi-dimension and method for compensating gain thereof - Google Patents

Abstract

The present invention relates to a communication signal relay system and a signal gain compensation method in the relay system. A relay system for relaying a communication signal of a base station according to the present invention to a terminal includes a forward signal from the base station to the communication terminal. A first donor unit received from the base station to compensate for and output a gain; A second donor unit for frequency upconverting the forward signal output from the first donor unit into a microwave band; And a first divider for branching the frequency up-converted forward signal to the plurality of antennas in the second donor unit.

Repeater, Repeater System, Donor, Splitter, Splitter, Gain, Compensation, Control, Base Station

Description

REPEATER SYSTEM FOR DIVIDING SIGNAL IN MULTI-DIMENSION AND METHOD FOR COMPENSATING GAIN THEREOF}

The present invention relates to a communication signal relay system, and more particularly, to a communication signal relay system for multi-dimensional signal distribution using a splitter and a signal gain compensation method in the relay system.

With the development of mobile communication, users' use forms and demands are also diversified, and they want to communicate without being restricted by time and space. However, the output of the radio wave transmitted from the base station is limited, and there is a shaded area due to problems such as the location and the topography of the base station. As a solution for eliminating the shadow area, a relay system that can obtain a predetermined effect at a low price is introduced. Areas where the relay system is installed include areas where calls cannot be made without artificially installing the relay system, such as underground, subway, tunnels, and apartment complexes in residential areas where radio waves cannot be received by terrains such as mountains and buildings. It is provided to small population areas, amusement parks, valleys, etc., where the volume of calls outside the base station's service area is low.

The relay system is composed of a donor unit installed in the base station and a remote unit installed in the target service area. The forward signal of the base station is converted into a frequency band for the link, that is, a microwave band, in the donor unit and transmitted to the remote unit, and in the remote unit, the signal is converted back into a signal in the same frequency band as that of the base station signal. Send to Meanwhile, the terminal signal in the reverse direction is transmitted to the base station through the remote unit and the donor unit in the same manner. Each unit improves the isolation between the input and output of the relay system by using the link signal of the frequency band different from the service frequency band, and maintains the high gain in the antenna facility environment with limited isolation, enabling high power transmission. It can be used to expand the call area of the base station.

However, in the conventional relay system, the signal transmission method between the base station and the remote location is 1: 1. That is, a signal transmission method from one donor unit to one remote unit is used. Therefore, there is a problem in that an additional donor unit must be installed in order to transmit the signal of the base station to the remote location every time the relay system is expanded. Accordingly, there is a problem in that facility investment costs increase due to the expansion of the relay system.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a relay system for eliminating the shadow area and a gain compensation method in the relay system without excessively increasing the facility investment cost.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

A relay system for relaying a communication signal of a base station according to a first aspect of the present invention for achieving the above object to a terminal, receiving a forward signal from the base station to the communication terminal from the base station to compensate and output the gain; 1 donor unit; A second donor unit for frequency upconverting the forward signal output from the first donor unit into a microwave band; And a first divider for branching the frequency up-converted forward signal to the plurality of antennas in the second donor unit.

In addition, according to a second aspect of the present invention, a first donor unit for compensating and outputting a gain of a forward signal from a base station to a communication terminal, and a forward signal output from the first donor unit are microwaves. A gain compensation method of the first donor unit in a relay system including a second donor unit frequency upconverting to a band may include receiving a sense signal for a signal divider connected to the second donor unit from the second donor unit ; Analyzing the received detection signal to determine a type of the signal splitter; And compensating for the gain of the forward signal according to the identified signal divider and outputting the gain to the second donor unit.

In addition, according to a third aspect of the present invention, a first donor unit for compensating and outputting a gain of a forward signal from a base station to a communication terminal, and a power supply and a forward signal from the first donor unit The gain compensation method of the first donor unit in a relay system including a splitter each branching and a plurality of second donor units operating on a power source branched from the splitter and frequency-converting the branched forward signal into a microwave band. Sending N status request signals through the distributor to the plurality of second donor units; Receiving through the distributor a status response signal according to the N status request signals; Analyzing the received status response signal to determine the number of second donor units connected to the distributor; And compensating for the gain of the forward signal according to the identified number of second donor units and outputting the gain to the splitter.

As described above, the present invention solves the cost problem of additionally installing a donor unit by using a splitter when a plurality of relay antennas are installed in a base station according to an extension of a repeater, thereby reducing facility costs due to the expansion of a repeater. There is an effect of ensuring good signal quality.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, in which: There will be. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing the configuration of a relay system according to an embodiment of the present invention.

As shown in FIG. 1, the relay system according to the present embodiment includes a base station (BTS / RNC) 110, a first donor unit 120, a second donor unit 130, a distributor 140, and a plurality of Antenna 150-N.

The base station 110 transmits a forward signal from the mobile communication network to the first donor unit 120, and also transmits a reverse signal received from the first donor unit 120 to the mobile communication network. The forward signal transmitted from the base station 110 to the first donor unit 120 or the reverse signal transmitted from the first donor unit 120 to the base station 110 is a commercial frequency band, for example, 800 MHz or It may be a frequency band of 1.8GHz. Alternatively, in case of WCDMA, the frequency band may be 2.1 GHz.

The first donor unit 120 is installed between the base station 110 and the second donor unit 130 in proximity to the base station 110 to supply power to the second donor unit 130 and also to provide a second donor unit ( 130 monitors and controls (e.g., gain control), forward signals from the base station 110 to the second donor unit 130, and also reverse the reverse signal from the second donor unit 130 Transfer to the base station 110. The first donor unit 120 may transmit the RF signal as it is or transmit the RF signal to an intermediate frequency (IF) signal in order to transmit the forward signal to the second donor unit 130. Preferably, the first donor unit 120 controls the gain according to the type of distributor 140 connected to the second donor unit 130 in transmitting the forward signal to the second donor unit 130. To pass.

The second donor unit 130 up-converts and amplifies the forward signal received from the first donor unit 130 into a microwave band of 11 GHz or 18 GHz to the distributor 140. Here, the first donor unit 120 and the second donor unit 130 are preferably connected by one cable, but are not necessarily limited thereto.

Here, when the dispenser 140 is connected, the second donor unit 130 transmits a switch signal regarding the type of the dispenser 140 to the first donor unit 120 so that the signal is received from the first donor unit 120. Allows you to control the gain. That is, the first donor unit 120 determines the type of the distributor 140 connected to the second donor unit 130 according to the switch signal from the second donor unit 130, and accordingly, the gain of the forward signal ( gain) is compensated and transferred to the second donor unit 130. An insertion loss occurs when the second donor unit 130 and the distributor 140 are connected to compensate for the insertion loss. This will be described later in detail. Meanwhile, FIG. 9 is an example of frequency arrangement of the forward path and the reverse path between the first donor unit 120 and the second donor unit 130. As illustrated in FIG. 9, the forward path and the reverse path may be provided in plural. The first and second donor units 120 and 130 for the signal gain compensation according to the distributor 140 including a traffic channel FA and one pilot channel, and the switch signal are shown in FIG. This is done via the frequency of the Link FSK.

The distributor 140 includes a plurality of output ports at one input port, and a plurality of antennas 150 -N are connected to the plurality of output ports, and branch the forward signal transmitted from the second donor unit 130. To transmit a signal to the plurality of antennas 150 -N through the plurality of output ports. The plurality of antennas 150 -N transmits the microwave signal of the microwave band branched from the distributor 140 to the remote location. In addition, the divider 140 receives a plurality of microwave band reverse signals received through the plurality of antennas 150-N through the plurality of output ports, synthesizes the signals, and transmits the reverse signals to the second donor unit 130. do.

As described above, in the communication signal relay system according to the present embodiment, the donor unit 130 and the plurality of antennas 150 are installed to transmit multiple microwave antennas 150 -N in one donor unit 130. -N) connects the signal divider 140. Conventionally, the signal transmission method between the base station and the remote location was 1: 1, but in the present invention, the signal transmission method between the base station and the remote location is 1: multiple transmission method. In such a multi-transmission scheme, rather than additionally installing a plurality of donor units, one donor unit is kept as it is and only an additional signal divider 140 is installed, thereby reducing the cost of the relay system.

Figure 2 is a view showing the appearance of the distributor of Figure 1, Figure 2 (a) is a divider 140a of the two-output port, Figure 2 (b) is a divider 140b of the three-output port, Figure 2 (c) shows the divider 140c of the 4-output port.

As shown in FIG. 2, each distributor 140a, 140b, 140c has one input port 141a, 141b, 141c and a plurality of output ports 143a, 143b, 143c. The input ports 141a, 141b, and 141c are SMA type connectors, and the output ports 143a, 143b, and 143c are N type connectors, but are not necessarily limited thereto.

On the other hand, as shown in Figure 2, each of the divider (140a, 140b, 140c) with the input port is formed with two push projections (145a, 145b, 145c) around the input port. At this time, the height protrusions of the push protrusions 145a, 145b, and 145c of each distributor 140a, 140b, and 140c differ from each other. That is, as shown in (a) of FIG. 2, the two push protrusions 145a of the two-output port splitter 140a have a height higher than the right side and 3 as shown in FIG. The two push protrusions 145b of the output port divider 140b have a higher height on the right side than the left side. That is, the pressing protrusions 145a and 145b of the two and three output port distributors 140a and 140b have opposite arrangement structures. On the other hand, the four-output port distributor 140c has the same height of the two push protrusions 145c.

3 is a view showing the specifications of the distributor of Figure 1, Figure 3 (a) is a specification of the two-output port distributor, Figure 3 (b) is a specification of the three-output port distributor, Figure 3 (c) Is the specification of the 4-output port splitter. Frequency range, insertion loss, return loss, isolation, amplitude unbalance, phase unbalance, and impedance. Typically, the insertion loss of a two-output port divider is up to 3.6 dB, the insertion loss of a three-output port divider is up to 5.6 dB, and the insertion loss of a four-output port divider is up to 7 dB.

4 is a view illustrating an external appearance of the second donor unit of FIG. 1. As illustrated in FIG. 4, the second donor unit 130 may include one input port 131 and one output port 133. Equipped. In addition, the switches 135a and 135b are located at positions corresponding to the push protrusions 145a, 145b, and 145c of the distributors 140a, 140b, and 140c on the surface where the output port 133 of the second donor unit 130 is provided. Is provided.

Specifically, when the second donor unit 130 and the distributors 140a, 140b, and 140c are connected, the switches 135a and 135b of the second donor unit 130 may be pushed by the pusher protrusions of the distributors 140a, 140b and 140c. 145a, 145b, and 145c are turned on and off, and the on / off signal is used to distinguish the types of distributors 140a, 140b, and 140c. When the 2-output port distributor 140a and the second donor unit 130 are connected, only the first push-out of the two push-outs 145a of the 2-output port distributor 140a of the second donor unit 130 may be used. The switch 135a is turned ON and the information that only the first push projection is turned ON is sent from the second donor unit 130 to the first donor unit 120. In addition, when the 3-output port distributor 140b and the second donor unit 130 are connected, only the second push protrusion of the two push protrusions 145b of the 3-output port distributor 140b is connected to the second donor unit 130. ), The switch 135b is turned ON, and the information that only the second push projection is turned ON is sent from the second donor unit 130 to the first donor unit 120. In addition, when the 4-output port distributor 140c and the second donor unit 130 are connected, the two push protrusions 145b of the 4-output port distributor 140c may switch 135a of the second donor unit 130. And 135b are all turned on, and information indicating that both of the pressing protrusions are turned on is sent to the first donor unit 120 through the second donor unit 130.

FIG. 5 is a block diagram illustrating some components of the first donor unit and the second donor unit of FIG. 1, and as shown in FIG. 5, the second donor unit 130 includes a switch detector 131. The 1 donor unit 120 includes a controller 121 and a gain compensator 123.

The switch detecting unit 131 of the second donor unit 130 is connected to the first and second switches of the second donor unit 130 to recognize the on / off of the first and second switches and to provide the on / off signal accordingly. Transfer to the first donor unit 120.

The control unit 121 of the first donor unit 120 receives a switch on / off signal from the switch detection unit 131 of the second donor unit 130 and is connected to the second donor unit 130. ), And outputs a control signal according to the analyzed result to the gain compensator 123. That is, upon receiving the (ON, OFF) signals for the first and second switches, it is determined that the two-output port divider 140a is connected to the second donor unit 130, or (OFF for the first and second switches). When receiving the (ON) signal, it is determined that the 3-output port splitter 140b is connected. When receiving the (ON, ON) signal, it is determined that the 4-output port splitter 140c is connected. If it receives a signal of (OFF, OFF), it determines that there is no distributor connected.

The gain compensator 123 of the first donor unit 120 compensates for the gain of the forward signal to be output to the second donor unit 130 according to the control signal of the controller 121. That is, when the control signal for the two-output port divider 140a is received, the gain compensator 123 compensates for the 3 dB gain for the forward signal, and the control signal for the three-output port divider 140b is received. 5dB gain compensation when the control signal for the 4-output port divider 140c is received, and 6dB gain compensation.

As described above, the first donor unit 120 compensates the gain of the forward signal according to the type of the distributor 140 connected to the second donor unit 130, thereby compensating for the gain loss caused by the insertion loss of the distributor 140. Can transmit a signal of quality.

6 is a flowchart illustrating a gain compensation method for a forward signal in a first donor unit according to an embodiment of the present invention.

As shown in FIG. 6, when the distributor 140 is connected to the second donor unit 130, the first or second switches 135a and 135b of the second donor unit 130 are pressed by the distributor 140. It is pressed by the projection and the related switch signal is transmitted from the second donor unit 130 to the first donor unit 120 (S601).

When the switch signal is received in this way, first the first donor unit 120 analyzes the received switch signal by the switch detector 121 and checks whether the second switch 135b is on (S603). .

When the second switch 135b is on, the first donor unit 120 analyzes the received switch signal again by the switch detector 121 to turn on the first switch 135a. Check whether it is (S605). When the first switch 135a is on, the first donor unit 120 determines that the 4-output port divider 140c is connected to the second donor unit 130 and determines a gain compensation value. That is, 6 dB is determined as a gain compensation value (S607). On the other hand, when the first switch 135a is off, the first donor unit 120 determines that the 3-output port divider 140b is connected to the second donor unit 130 and determines a gain compensation value. do. That is, 5 dB is determined as the gain compensation value (S609).

On the other hand, when the second switch 135b is off as a result of the checking in step S603, the first donor unit 120 analyzes the received switch signal by the switch detector 121 again to determine the first. It is checked whether the switch 135a is on (S611).

When the first switch 135a is on, the first donor unit 120 determines that the two-output port divider 140a is connected to the second donor unit 130 and determines a gain compensation value. That is, 3 dB is determined as the gain compensation value (S613). On the other hand, when the first switch 135a is off, the first donor unit 120 determines that the distributor is not connected to the second donor unit 130 and determines that gain compensation is not performed (S615). ).

After the gain compensation value for the forward signal is determined as described above, the first donor unit 120 compensates and outputs the gain of the forward signal to be transmitted to the second donor unit 130 (S617). As a result, the forward signal input to the first donor unit 120 is output by adding the determined gain to the basic gain of the first donor unit 120. Therefore, good quality signal transmission is possible in the multi-dimensional multiplexing transmission by a plurality of antennas.

7 is a diagram showing the configuration of a relay system according to another embodiment of the present invention.

As shown in FIG. 7, the relay system according to the present embodiment includes a base station (BTS / RNC) 710, a first donor unit 720, a bias-T divider 730, and a plurality of seconds. Donor unit 740 -N and antenna 750 -N.

The base station 710 transmits a forward signal from the mobile communication network to the first donor unit 720, and also forwards a reverse signal received from the first donor unit 720 to the mobile communication network. The forward signal transmitted from the base station 710 to the first donor unit 720 or the reverse signal transmitted from the first donor unit 720 to the base station 110 is a commercial frequency band, for example, 800 MHz or It may be a frequency band of 1.8GHz. Alternatively, in case of WCDMA, the frequency band may be 2.1 GHz.

The first donor unit 720 is installed in close proximity to the base station 710 to supply power to the bias-T distributor 730 and the second donor unit 740 -N and to monitor the second donor unit 740 -N. And control (eg, gain control and power supply). The first donor unit 720 transmits the forward signal and power from the base station 710 to the bias-T distributor 730, and also forwards the reverse signal to the base station 710. The first donor unit 720 may transmit the RF signal as it is or transmit the RF signal to an intermediate frequency (IF) signal in order to transmit the forward signal to the second donor unit 740 -N.

Preferably, the first donor unit 720 gains in accordance with the number of second donor units 740 -N in transferring the forward signal through the bias-T divider 730 to the second donor unit 740 -N. Pass the signal by controlling the gain. The first donor unit 720 determines a compensation gain value according to Equation 1 below to compensate for the forward signal gain. Accordingly, the first donor unit 720 may include receiving means for receiving a sense signal regarding the number of second donor units 740 -N connected to the bias-T distributor 730 from the bias-T distributor 730, and the same. Gain compensation means for compensating for the gain of the forward signal in accordance with the sense signal received at the receiving means.

Compensation gain value = -10 * log (N), where N is the number of second donor units

A bias tee divider 730 has one input port and a plurality of output ports and branches each of the forward and voltage signals received from the first donor unit 720 cabled to the input port. To distribute to the plurality of second donor units 740 -N through the plurality of output ports. In the present embodiment, the divider 730 of the bias-T function is described as an example of receiving and distributing an RF signal and a voltage signal, but if each DC signal can be distributed after receiving and separating the sum of the DC signals. Either may be used.

The second donor unit 740 -N is operated by the power distributed in the bias-T divider 730 to remotely forward the forward signal distributed in the bias-T divider 730 via the antenna 750 -N. send. In this case, the second donor unit 740 -N up-converts and amplifies the forward signal into a microwave band of 11 GHz or 18 GHz and transmits the signal to a remote location through the antenna 750 -N.

As described above, in the communication signal relay system according to the present embodiment, relay coverage may be extended by installing a plurality of donor units 740-N at one base station and performing multiplexing of forward signals. In this case, in the communication signal relay system according to the present embodiment, the use of the bias-T divider 730 enables the support of the plurality of donor units 740 -N, thereby reducing the facility cost for expansion of the relay coverage. In particular, it compensates for the reduction in signal power that may occur by using the bias-T divider 730 to establish relay coverage with the same output as when using one antenna.

8 is a flowchart illustrating a gain compensation method for a forward signal in a first donor unit according to another embodiment of the present invention.

As shown in FIG. 8, first, information about a second donor unit 740 -N that may be connected to the bias-T distributor 730 is set in the first donor unit 720 (S801). This setting may be made by an administrator or may be made automatically by remote setting.

After the information on the second donor unit 740 -N is set in the first donor unit 720, the bias-T distributor 730 is connected to the first donor unit 720, and the bias-T After a plurality of second donor units 740 -N are connected to the distributor 730, the first donor unit 720 sends N state request signals for the second donor unit 740 -N to the bias-T. The second donor unit 740 -N is transmitted through the distributor 730 (S803). The first donor unit 720 sets and transmits N state request signals by using the information on the set second donor unit 740 -N. Preferably, the status request signal includes identification information on the second donor unit.

The second donor unit 740 -N connected to the bias-T distributor 730 transmits a status response signal to the first donor unit 720 in response to the status request signal from the first donor unit 720. Here, the status response signal includes identification information of the second donor unit 740 -N. The first donor unit 720 receives a state response signal transmitted from the second donor unit 740 -N (S805), and analyzes the received state response signal to generate a second connected to the bias-T distributor 730. The number of donor units 740-N is checked (S807). That is, the number is confirmed using the identification information of the second donor unit.

Subsequently, the first donor unit 720 determines a compensation gain value for the forward signal according to the identified number of second donor units 740 -N (S809). Preferably, the first donor unit 720 determines a compensation gain value for the forward signal according to Equation 1 above.

After determining the compensation gain value, the first donor unit 720 compensates the gain of the forward signal to be transmitted to the bias-T divider 730 according to the determined compensation gain value (S811). As a result, the forward signal transmitted from the first donor unit 720 to the bias-T divider 730 is amplified by the compensation gain value to the basic gain value of the first donor unit 720 to be biased to the bias-T divider 730. Is passed to. Therefore, the same power coverage can be maintained by compensating for signal power attenuation generated by signal distribution by the bias-T divider 730 to maintain the same end output as when using one antenna even when using multiple antennas. .

As described above, an embodiment of the relay system according to the present invention has been described with reference to FIGS. 1 and 7. Referring to FIG. 1, the relay system employs a divider between the second donor unit and the antenna to allow a plurality of antennas to be connected to one second donor unit to expand the relay coverage without increasing the facility investment cost. In addition, the relay system referring to FIG. 2 employs a divider having a bias-T function between the first donor unit and the second donor unit to connect a plurality of second donor units to one first donor unit, thereby relaying the reference to FIG. 1. Like the system, it allows for extended relay coverage without increasing facility investment costs.

On the other hand, it is possible to construct a relay system combining the embodiment with reference to FIG. 1 and the embodiment with reference to FIG. 2. That is, a relay system can be constructed by connecting a divider having a bias-T function to the first donor unit and the second donor unit, and also connecting a divider between the second donor unit and the antenna terminal. In this case, compared to the relay system described with reference to FIGS. 1 and 2, a plurality of antennas may be extended, thereby extending relay coverage.

The method of the present invention as described above may be embodied as a program and stored in a computer-readable recording medium (such as a CD-ROM, a RAM, a ROM, a floppy disk, a hard disk, or a magneto-optical disk). Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is a view showing the configuration of a relay system according to an embodiment of the present invention.

FIG. 2 is a view showing an external appearance of the distributor of FIG. 1.

3 is a view showing the specification of the distributor of FIG.

4 is a view illustrating an external appearance of the second donor unit of FIG. 1.

FIG. 5 is a block diagram illustrating a configuration of the first donor unit of FIG. 1.

6 is a flowchart illustrating a gain compensation method for a forward signal in a first donor unit according to an embodiment of the present invention.

7 is a diagram showing the configuration of a relay system according to another embodiment of the present invention.

8 is a flowchart illustrating a gain compensation method for a forward signal in a first donor unit according to another embodiment of the present invention.

9 is a frequency diagram of the forward path and the reverse path between the first donor unit and the second donor unit.

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

110: base station 120: first donor unit

130: second donor unit 140: distributor

150-N: Antenna

Claims (10)

A relay system for relaying a communication signal of a base station to a communication terminal, A first donor unit receiving a forward signal from the base station to the communication terminal from the base station to compensate for and output a gain; A second donor unit for frequency upconverting the forward signal output from the first donor unit into a microwave band; And And a first divider which branches the frequency up-converted forward signal to the plurality of antennas in the second donor unit. When the first distributor is connected to the second donor unit, the second donor unit transmits a switch signal according to the connection to the first donor unit, The first donor unit, the relay system by analyzing the switch signal to determine the type of the first divider to compensate for the gain of the forward signal. delete The method of claim 1, The second donor unit includes two switches on a side surface connected to the first distributor, and transmits a switch signal according to a pressed state of the switch to the first donor unit, And the first donor unit compensates for the gain of the forward signal according to the switch signal. The method of claim 1, And a second divider for branching each of the power and forward signals from the first donor unit into a plurality of second donor units. The method of claim 4, wherein The first donor unit, And compensate for the gain of the forward signal according to the number of second donor units connected to the second distributor. In the relay system comprising a first donor unit for compensating and outputting the gain of the forward signal from the base station to the communication terminal, and a second donor unit for frequency up-converting the forward signal output from the first donor unit to the microwave band As a gain compensation method of the first donor unit, (a) receiving a switch signal from the second donor unit according to the connection of the signal divider as the signal divider is connected to the second donor unit; (b) analyzing the received switch signal to identify a type of the signal splitter; (c) compensating for the gain of the forward signal according to the identified type of signal divider and outputting the gain to the second donor unit. delete A first donor unit for compensating and outputting a gain of a forward signal from a base station to a communication terminal, a splitter for branching a power source and a forward signal from the first donor unit, and a branch operating at a branched power source in the distributor; A gain compensation method of the first donor unit in a relay system including a plurality of second donor units for frequency upconverting the forward signal into a microwave band, (a) transmitting N status request signals through the distributor to the plurality of second donor units; (b) receiving through the distributor a status response signal according to the N status request signals; (b) analyzing the received status response signal to determine the number of second donor units connected to the distributor; (c) compensating for the gain of the forward signal according to the identified number of second donor units and outputting the gain to the splitter. The method of claim 8, Before step (a), Setting information about a second donor unit that can be connected to the dispenser; And transmitting the status request signal of step (a) based on the information on the set second donor unit. 10. The method according to claim 8 or 9, And the identification information of the second donor unit is included in the status response signal.

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