KR102189724B1 - Method for arranging crest factor reduction device of distributed antenna system - Google Patents

Abstract

A distributed antenna system according to an aspect according to the technical idea of the present invention includes at least one headend unit for receiving mobile communication signals from a plurality of base stations, and at least one headend unit and is communicatively connected to at least one headend unit. It includes at least one remote unit that receives a mobile communication signal from an end unit and is disposed remotely to transmit a mobile communication signal to a terminal within the service coverage, and at least one remote unit is a movement transmitted from at least one headend unit. It includes a signal summing unit for digitally summing communication signals and a CFR module disposed at a rear end of the signal summing unit based on a signal transmission direction.

Description

CFR arrangement method in distributed antenna system {METHOD FOR ARRANGING CREST FACTOR REDUCTION DEVICE OF DISTRIBUTED ANTENNA SYSTEM}

The technical idea of the present invention relates to a technology related to a signal distribution system, and more particularly, to a method for distributing CFR (Crest Factor Reduction, CFR) in a distributed antenna system (DAS).

CFR is used a lot as a technique to reduce the Peak-to-Average Power Ratio (PAPR) of a signal. In particular, in a system using Digital Pre-Distorter (DPD), CFR is implemented in front of DPD to improve system efficiency.

In the case of DAS, these CFRs are generally implemented in the front of DPD in a remote unit (RU) among the node units constituting the DAS. I can. In addition, when multi-band signal processing is required for the RU of the DAS, CFR is required as much as the number of bands, and thus the complexity of the RU is greatly increased.

The technical problem to be achieved by the technical idea of the present invention is to provide a method of arranging CFR (Crest Factor Reduction) at an optimal position according to each topology type or design method in a distributed antenna system.

A distributed antenna system according to an aspect of the inventive concept includes at least one headend unit for receiving a mobile communication signal from a plurality of base stations; And at least one remote unit that is communicatively connected to the at least one headend unit, receives the mobile communication signal from the at least one headend unit, and is remotely disposed to transmit the mobile communication signal to a terminal within service coverage. Including, wherein the at least one remote unit is disposed at a rear end of the signal summing unit based on a signal summing unit and a signal transmission direction for digitally summing mobile communication signals transmitted from the at least one headend unit. Includes CFR module.

In an exemplary embodiment, the at least one remote unit receives a mobile communication signal transmitted from the at least one headend unit and separates only a signal corresponding to a specific mobile communication service band among the input mobile communication signals. May contain more wealth.

In an exemplary embodiment, the signal summing unit may perform digital signal summing for different subband signals within the same mobile communication service band among signals band-separated by the band separation unit.

A distributed antenna system according to another aspect of the inventive concept includes at least one headend unit for receiving a mobile communication signal from a plurality of base stations; And at least one remote unit that is communicatively connected to the at least one headend unit, receives the mobile communication signal from the at least one headend unit, and is remotely disposed to transmit the mobile communication signal to a terminal within service coverage. Including, wherein the at least one remote unit comprises a group delay equalization processor that performs group delay equalization processing on mobile communication signals transmitted from the at least one headend unit, and the group delay based on a signal transmission direction. It includes a CFR module disposed at the rear end of the equalization processor.

According to embodiments according to the technical idea of the present invention, there is an effect of arranging CFR (Crest Factor Reduction) at an optimal position according to each topology type or design method in a distributed antenna system.

Brief description of each drawing is provided in order to more fully understand the drawings cited in the detailed description of the present invention.
1 is a diagram illustrating an example of a topology of a distributed antenna system as a form of a signal distributed transmission system to which the technical idea of the present invention can be applied.
2 is a block diagram of an embodiment of a remote unit in a distributed antenna system to which the technical idea of the present invention can be applied.
3 is a diagram showing one form of a topology of a distributed antenna system for explaining an embodiment according to the technical idea of the present invention.
4 is a view for explaining a CFR arrangement method according to an embodiment according to the technical idea of the present invention.
5 is a view showing another form of a topology of a distributed antenna system for explaining an embodiment according to the technical idea of the present invention.
6 is a view for explaining a CFR arrangement method according to another embodiment according to the technical idea of the present invention.
7 is a view for explaining a CFR arrangement method according to another embodiment according to the technical idea of the present invention.

The technical idea of the present invention is a bar that can apply various transformations and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the technical idea of the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, and substitutes included in the scope of the technical idea of the present invention.

In describing the technical idea of the present invention, when it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, numbers (eg, first, second, etc.) used in the description of the present specification are merely identification symbols for distinguishing one component from another component.

In addition, in the present specification, when one component is referred to as "connected" or "connected" to another component, the one component may be directly connected or directly connected to the other component, but specially It should be understood that as long as there is no opposing substrate, it may be connected or may be connected via another component in the middle.

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

Hereinafter, a distributed antenna system will be described as an application example to which embodiments according to the technical idea of the present invention can be applied. However, the embodiment according to the technical idea of the present invention is equally or similarly applicable to other signal distributed transmission systems such as a base station distributed system in addition to the distributed antenna system.

1 is a diagram illustrating an example of a topology of a distributed antenna system as a form of a signal distributed transmission system to which the technical idea of the present invention can be applied.

Referring to FIG. 1, a distributed antenna system (DAS) includes a base station interface unit (BIU) 10 and a main unit (MU) 20 constituting a headend node of a distributed antenna system, and an expansion node. It includes a hub unit (HUB) 30 that is an extension node, and a plurality of remote units (RUs) 40 disposed at each remote service location. Such a distributed antenna system may be implemented as analog DAS or digital DAS, and in some cases, may be implemented as a hybrid type thereof (that is, some nodes perform analog processing and other nodes perform digital processing).

However, FIG. 1 shows an example of a topology of a distributed antenna system, and the distributed antenna system includes an installation area and an application field (eg, In-Building, Subway, Hospital, Various topology modifications are possible in consideration of the specificity of the stadium (Stadium, etc.). To this effect, the number of BIUs 10, MUs 20, HUBs 30, and RUs 40 and a connection relationship between upper and lower ends thereof may be different from that of FIG. 1. In addition, in the distributed antenna system, the HUB 20 is used when the number of branches to be branched from the MU 20 to a star structure is limited compared to the number of RUs 40 required for installation. Therefore, the HUB 20 may be omitted when the number of RUs 40 required for installation can be sufficiently covered by only a single MU 20 or when a plurality of MUs 20 are installed.

Hereinafter, each node in a distributed antenna system that can be applied to the technical idea of the present invention and its functions will be sequentially described, centering on the topology of FIG. 1.

A base station interface unit (BIU) 10 serves as an interface between a base station transceiver system (BTS) 5 such as a base station and the MU 20 in a distributed antenna system. In FIG. 1, a case in which a plurality of BTSs 5 are connected to a single BIU 10 is illustrated, but the BIU 10 may be separately provided for each operator, for each frequency band, and for each sector.

In general, the RF signal (Radio Frequency signal) transmitted from the BTS (5) is a high power signal, so in general, the BIU (10) is suitable for processing such a high power RF signal in the MU (20). It converts into a signal of and transmits it to the MU 20. In addition, depending on the implementation method, the BIU 10 receives a signal of a mobile communication service for each frequency band (or for each operator, for each sector) as shown in FIG. 1 and combines the signal, and then the MU 20 It can also perform the function of passing to ).

If the BIU 10 lowers the high power signal of the BTS 5 to low power and then combines each mobile communication service signal and transmits it to the MU 20, the MU 20 combines and transmits the mobile communication service signal ( Hereinafter, this is referred to as a relay signal) is distributed for each branch. At this time, when the distributed antenna system is implemented as a digital DAS, the BIU 10 converts the high power RF signal of the BTS 5 into a low power RF signal, and an IF signal (Intermediate Frequency) for the low power RF signal. signal), digital signal processing, and then combine it into a separate unit. Unlike the above, if the BIU 10 performs only the function of lowering the high power signal of the BTS 5 to low power, the MU 20 combines each transmitted relay signal and distributes it for each branch. .

As described above, the combined relay signal distributed from the MU 20 is branch-specific (see Branch #1, …, Branch #k, …, Branch #N in FIG. 1) through the HUB 20 or RU ( 40), and each RU 40 separates the received combined relay signal by frequency band and performs signal processing (analog signal processing in the case of analog DAS, and digital signal processing in the case of digital DAS). Accordingly, each RU 40 transmits a relay signal to a user terminal within its service coverage through a service antenna. In this case, a detailed functional configuration of the RU 40 will be described later in detail with reference to FIG. 2.

In the case of FIG. 1, it shows a case where both the BTS 5 and the BIU 10 and the BIU 10 and the MU 20 are connected by an RF cable, and all from the MU 20 to the lower end thereof are connected by an optical cable. However, the signal transport medium between each node is also capable of various modifications. For example, the BIU 10 and the MU 20 may be connected through an RF cable, but may be connected through an optical cable or a digital interface. As another example, the MU (20) and the HUB (30) and the RU (40) directly connected to the MU (20) is connected by an optical cable, and the cascade connected RU (40) is connected to each other by an RF cable, a twist cable, UTP. It can also be implemented in a way that is connected through a cable or the like. As another example, as another example, the RU 40 directly connected to the MU 20 may also be implemented in a manner that is connected through an RF cable, a twist cable, a UTP cable, or the like.

However, hereinafter, it will be described with reference to FIG. 1. Accordingly, in the present embodiment, the MU 20, HUB 30, and RU 40 may include an optical transceiver module for electro-optical conversion/photoelectric conversion, and when nodes are connected by a single optical cable, WDM ( Wavelength Division Multiplexing) device may be included. This will be clearly understood through the functional description of the RU 40 in FIG. 2 to be described later.

This distributed antenna system may be connected to an external management device, for example, a Network Management Server or System (NMS) 50 through a network. Accordingly, the administrator can remotely monitor the state and problem of each node of the distributed antenna system through the NMS 50 and control the operation of each node remotely.

2 is a block diagram of an embodiment of a remote unit in a distributed antenna system to which the technical idea of the present invention may be applied.

Here, the block diagram of FIG. 2 illustrates an implementation form of the RU 40 in the digital DAS in which the connection between nodes is made through an optical cable. In addition, the block diagram of FIG. 2 shows only a configuration unit related to a function of providing a service signal to a terminal in a service area through a forward path and processing a terminal signal received from a terminal in the service area through a reverse path.

Referring to FIG. 2, the RU 40 includes an optical to electrical converter 50, a serializer (SERDES) based on a downlink signal transmission path (ie, a forward path). /Deserializer (44), Deframer (52), Digital Signal Processing Unit (DSP) (70), Digital/Analog Converter (DAC) (54), Up Converter (56), PAU (Power Amplification Unit) 58.

Accordingly, in the forward path, the optical relay signal digitally transmitted through the optical cable is converted into an electric signal (serial digital signal) by the optical/electric converter 50, and the serial digital signal is converted to a parallel digital signal by the SERDES 44. It is converted into a signal, and the parallel digital signal is reformatted by the deframer 52 so that the digital signal processing unit 70 can process each frequency band. The digital signal processing unit 70 performs functions such as digital signal processing, digital filtering, gain control, and digital multiplexing for each frequency band of the relay signal. The digital signal that has passed through the digital signal processing unit 70 is converted into an analog signal through a digital/analog converter 54 constituting the final stage of the digital part 84 based on the signal transmission path. At this time, since the analog signal is an IF signal, the frequency is up-converted to an analog signal of the original RF band through the up converter 56. In this way, the analog signal (ie, RF signal) converted to the original RF band is heavy through the PAU 58 and transmitted through a service antenna (not shown).

Based on the uplink signal transmission path (ie, reverse path), the RU 40 includes a low noise amplifier (LNA) 68, a down converter 66, and an analog/digital converter (ADC). (64), a digital signal processing unit (DSP) 70, a framer (62), SERDES (44), and an electric/optical converter (Electrical to Optical Converter) 60.

Accordingly, in the reverse pass, the RF signal (i.e., the terminal signal) received through the service antenna (not shown) from the user terminal (not shown) within the service coverage is low-noise amplified by the LNA 68, which is a down converter ( 66), the converted IF signal is converted into a digital signal by the analog/digital converter 64 and transmitted to the digital signal processing unit 70. The digital signal passed through the digital signal processing unit 70 is formatted in a format suitable for digital transmission through the framer 62, which is converted into a serial digital signal by the SERDES 44, and the electric/optical converter 60 It is converted into an optical digital signal and transmitted to the upper end through an optical cable.

In addition, although not clearly shown in FIG. 2, in a state in which the RUs 40 are cascaded with each other as in the example of FIG. 1, when the relay signal transmitted from the upper end is transferred to the adjacent RU of the lower end cascaded Can be done in the following way. For example, when transmitting an optical relay signal digitally transmitted from the upper end to the adjacent RU of the lower end connected to the casecade, the optical relay signal digitally transmitted from the upper end is an optical/electric converter 50 -> SERDES 44- > Deframer 52 -> Framer 62 -> SERDES 44 -> All/optical converter 60 may be transferred to the adjacent RU through the sequence. This will be clearly understood through FIG. 4 to be described later.

In FIG. 2 described above, the SERDES 44, the deframer 52, the framer 62, and the digital signal processing unit 70 may be implemented as a Field Programmable Gate Array (FPGA). In addition, although FIG. 2 shows that the SERDES 44 and the digital signal processing unit (DSP) 70 are shared in the downlink and uplink signal transmission paths, these may be separately provided for each path. In addition, in FIG. 2, the photo/electric converter 50 and the electro/optical converter 60 are shown as being separately provided, but this is a single optical transceiver module (e.g., a single Small Form Factor Pluggable (SFP) (Fig. 2, reference numeral 82)).

In the above, a topology of a form of a distributed antenna system and a configuration example of an RU have been described with reference to FIGS. 1 and 2. In particular, in FIG. 2, the RU in the digital DAS digitally transmitted through a transmission medium has been described. However, it goes without saying that the technical idea of the present invention can be applied to various other applications.

Hereinafter, a CFR arrangement method according to various embodiments according to the technical idea of the present invention will be described for each embodiment with reference to FIGS. 3 to 7.

First Example - HEU(M):HUB(1):RU(N) In topology CFR arrangement

As a first embodiment, in a distributed antenna system, in a topology of a plurality (M) of HEUs, a single HUB, and a plurality of (N) RUs (refer to the topology of FIG. 3 or 5), CFR is implemented on the HUB side. As a result, signal degradation and RU complexity can be reduced.

3 or 5, the distributed antenna system includes a plurality of headend units (HEUs) (100A, 100B, 100C), a single hub unit (HUB) 200, and a single HUB 200. It includes a plurality of RUs connected in a star structure or/and a cascade structure.

In the topology of FIG. 3 or 5, each HEU (100A, 100B, 100C) transmits a mobile communication signal of a plurality of mobile communication service bands received from a plurality of BTSs in a baseband or intermediate frequency band. Then, the digitally converted mobile communication signal may be transmitted to the HUB 200 by performing digital signal conversion on the band-converted mobile communication signal.

In the topology of Fig. 3, each HEU (100A, 100B, 100C) receives a mobile communication signal of a specific mobile communication service band from a plurality of BTSs through a transmission medium. In the example of FIG. 3, each HEU (100A, 100B, 100C) exemplifies a case in which a signal in a WCDMA band, a signal in an LTE band, and a signal in an LTE-A band is received from three BTSs. In addition, it is assumed that each HEU (100A, 100B, 100C) receives mobile communication signals from different mobile communication operators. In FIG. 3, it is assumed that one HEU and one mobile communication service provider are matched one-to-one, but it is of course not limited thereto. On the other hand, in the topology of FIG. 5, each HEU (100A, 100B, 100C) exemplifies a case in which signals for different sectors within a specific mobile communication service band are received through a transmission medium.

In the above-described HEU(M):HUB(1):RU(N) topology, the CFR module (refer to reference numeral 1040 of FIG. 4 or 6 to be described later) is a plurality of HEUs when the signal transmission direction is referenced. It may be disposed after the mixing processing stage in the HUB that performs digital mixing processing on the mobile communication signals respectively received from In the above topology, as the CFR module is disposed after the mixing processing stage in the HUB, signal degradation (ie, complementary cumulative distribution function (CCDF) degradation) can be minimized.

Hereinafter, referring to FIG. 4 based on the topology of FIG. 3, and referring to FIG. 5 based on the topology of FIG. 3, a CFR arrangement method according to an embodiment of the present invention will be sequentially described. do.

FIG. 4 is a diagram illustrating components constituting a mixed processing unit related to a description of a CFR arrangement position according to an embodiment of the present invention among digital parts implemented in a HUB or HEU. However, in the present description, since the topology of HEU(M):HUB(1):RU(N) of FIG. 3 is assumed, the components of FIG. 4 are implemented in the HUB in an embodiment according to the technical idea of the present invention.

Referring to FIG. 4, the mixing processing stage implemented in the digital part of the HUB 200 may include a signal branching unit 1010, a band separation unit 1020, and a signal summing unit 1030. .

The signal branching unit 1010 performs a function of branching a signal so that the mobile communication signal transmitted from each HEU (100A, 100B, 100C) can be input to a digital filter for each mobile communication service band in the band separation unit 1020. do. For example, a mobile communication signal of mobile communication service provider A (refer to (A) of FIG. 4) is input from HEU of 100A to HUB 200, and movement of mobile communication servicer B from HEU of 100B A communication signal (refer to the reference numeral (B) in Fig. 4) is input to the HUB 200, and the mobile communication signal of the mobile communication service provider C (refer to the reference numeral (C) in Fig. 4) from the HEU at 100C is HUB ( 200) is assumed. In this case, a signal input to the HUB 200 for each mobile communication service provider may include a mobile communication signal of a WCDMA band, an LTE band, and an LTE-A band.

The mobile communication signal for each mobile communication service provider is divided into a digital filter for each service band (digital filter for separating the WCDMA band in Fig. 4, a digital filter for separating the LTE band, and LTE-A band through the signal branch unit 1010). Can be input as a digital filter for separation).

As described above, the band separating unit 1020 performs a function of separating only a signal corresponding to a corresponding service band by providing a digital filter for each service band. 4, the mobile communication signal (A) of the mobile communication service provider A, the mobile communication signal (B) of the mobile communication service provider B, and the mobile communication signal (C) of the mobile communication service provider C are applied to the digital filter for each service band. In this case, reference numeral (a1) denotes a signal in the WCDMA band among mobile communication signals (A) of mobile communication service provider A, and reference numeral (b1) refers to a mobile communication signal (B) of mobile communication service provider B. It means a signal in the WCDMA band, and the reference numeral (c1) denotes a signal in the WCDMA band among the mobile communication signals (C) of the mobile communication service provider C. In the same way as above, reference numerals (a2), (b2), (c2) denote LTE band signals among mobile communication signals of each mobile communication service provider, and reference numerals (a3), (b3), and (c3) refer to It refers to a signal in the LTE-A band among mobile communication signals of each mobile communication service provider.

As described above, when a signal for each mobile communication service provider passes through the band separation unit 1020, each subband (Sub-band 1, Sub-band) within the same mobile communication service band, as in reference numeral 1020A of FIG. 2, Sub-band 3) Signal can be extracted. Here, sub-band 1 conceptually shows the frequency band used by mobile communication service provider A in the process of providing a specific mobile communication service, and sub-band 2 refers to mobile communication service provider B in the process of providing a specific mobile communication service. The frequency band used is conceptually illustrated, and Sub-band 3 conceptually illustrates the frequency band used by the mobile communication service provider C in the process of providing a specific mobile communication service.

Each subband signal separated by the same mobile communication service band through the band separation unit 1020 as described above is input to the signal summing unit 1030. In an embodiment according to the technical idea of the present invention, the signal summing unit 1030 primarily digitally summing different subband signals in the same mobile communication service band input through the band separation unit 1020 (Refer to the 1032 constituent part of FIG. 4), the signal for each band thus summed is finally digitally summed (refer to the 1034 constituent part of FIG.

As described above, when a plurality of subband signals exist within the same mobile communication service band, and at this time, when digital signal summing is performed in the HUB 200, CFR processing is performed after the digital signal summing is performed, thereby minimizing signal deterioration. can do. Accordingly, in FIG. 4, the CFR module 1040 is disposed at the rear end of the signal summing unit 130.

In the above, the case of summing subband signals for each of the same mobile communication service band for forward mobile communication signals each received from a plurality of HEUs is exemplified, but in the case of summing various digital signals, the CFR module adds the final signal. However, it can be placed at the rear end.

FIG. 6 is a diagram illustrating components constituting a mixed processing unit related to a description of a CFR arrangement position according to another embodiment of a digital part implemented in a HUB or HEU. However, in the present description, since the topology of HEU(M):HUB(1):RU(N) of FIG. 5 is assumed, the components of FIG. 6 are implemented in the HUB in an embodiment according to the technical idea of the present invention.

Referring to FIG. 6, the mixed processing stage implemented in the digital part of the HUB 200 includes a signal swap unit 1050, and at this time, the CFR module 1040 includes a signal swap unit ( 1050) can be placed at the rear end.

As shown in FIG. 5, when a plurality of HEUs (100A, 100B, 100C) receive different sector signals in the same mobile communication service band and transmit them to the HUB 200, the sector swap processing is required in the HUB 200. In this case, the CFR module 1040 may be disposed at a rear end of the signal swap unit 1050 that performs signal swap processing. Referring to FIG. 6, an input signal for each sector (see sector A, sector B, and sector C of FIG. 6) is subjected to a frequency band swap process by a signal band swap processor 1052, and the swap-processed signals are summed. The CFR module 1040 is disposed at the rear end of the configuration (refer to the configuration unit of reference numeral 1054 in FIG. 6).

Second Example - HEU(1):RU(N) or HEU (One): HUB(1):RU(N) In topology CFR arrangement

As a second embodiment, when the distributed antenna system is implemented in the form of a topology of a single HEU and a plurality (N) RUs or a single HEU, a single HUB, and a plurality (N) RUs, the CFR is By implementing it, signal degradation and RU complexity can be reduced.

In this case, in the HEU, a plurality of base stations or single/multiple operators are connected to one, and may be connected to N RUs through a single HUB or directly in a star or/and cascade structure. In this case, when the HEU transmits a signal to the HUB or directly to the N RUs, the mobile communication signal received for each base station may be digitally summed and then transmitted. In this case, since digital signal summation is finally performed in the HEU, it is preferable that the CFR is implemented in the HEU. In this case, the CFR module is preferably disposed at the rear end of the signal summing unit (refer to reference numeral 1030 in FIG. 4) as described above. In addition, as described above with reference to FIG. 6, when it is necessary to perform sector swap in the HEU, the CFR module is preferably disposed at the rear end of the signal swap unit (refer to reference numeral 1050 in FIG. 6).

Third Example - In RU CFR arrangement

As described above through the previous embodiments, when there are multiple subband signals in the same mobile communication service band, it is necessary to separate and sum signals for each band.In this case, CCDF deterioration when CFR is performed after signal summing processing. Can be prevented.

For example, if the final signal summation is calculated in HEU or HUB, CFR can be implemented in HEU or HUB, but in some cases (for example, due to transmission capacity reduction, etc.), when the RU is serviced by summation of signals Can occur. Accordingly, in this case, the CFR may be implemented at the rear end of the signal summing unit (refer to 1030 of FIG. 4) implemented in the digital part of the RU side. This has been described in detail through the description of FIG. 4 above, and redundant descriptions will be omitted.

In addition, there are cases in which the CFR in the RU can minimize signal deterioration, which will be described with reference to FIG. 7. 7 illustrates a case in which a group delay equalization processing function is implemented in a digital part of an RU. The group delay equalization process may be used to equalize delays between a plurality of subband signals within the same mobile communication service band. For example, in the case of an LTE signal using the OFDM scheme, it is important to equalize the delay between subband signals. To this end, the digital part of the RU may include a signal branching unit 1110, a subband digital filter 1120, and a group delay equalization processor 1150 as shown in FIG. 7. In this case, the CFR module 1140 is disposed at the rear end of the group delay equalization processor 1150 that performs group delay equalization processing on the received mobile communication signal when the signal transmission direction is referenced. , Signal degradation can be minimized.

In the above, description has been made with reference to various embodiments according to the technical idea of the present invention, but those of ordinary skill in the art, the present invention within the scope not departing from the technical idea of the present invention described in the claims below. It will be easy to understand that various modifications and changes can be made to the technical idea of

Claims (4)

At least one headend unit for receiving mobile communication signals from a plurality of base stations; And
At least one remote unit communicatively connected to the at least one headend unit, receiving the mobile communication signal from the at least one headend unit, and being remotely disposed to transmit the mobile communication signal to a terminal within service coverage; Including,
The at least one remote unit,
A band separating unit for receiving a mobile communication signal transmitted from the at least one headend unit and separating only a signal corresponding to a specific band among the input mobile communication signals;
A signal summing unit digitally summing the mobile communication signals for each frequency band separated by the band separation unit; And
Distributed antenna system comprising a CFR module disposed at the rear end of the signal summing unit based on a signal transmission direction.
delete The method of claim 1,
The signal summing unit performs digital signal summing for different sub-band signals within the same mobile communication service band among signals band-separated by the band separation unit.

delete

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