KR20200016311A - Method for arranging crest factor reduction device of distributed antenna system - Google Patents

Abstract

According to an embodiment of the present invention, a distributed antenna system comprises: at least one headend unit which receives a mobile communication signal from a plurality of base stations; at least one remote unit which 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 in a service coverage. The at least one remote unit comprises: a group delay equalization processor which performs group delay equalization processing on the mobile communication signal transmitted from the at least one headend unit; and a crest factor reduction (CFR) module disposed at a rear end of the group delay equalization processor based on a signal transmission direction.

Description

CFR Placement in Distributed Antenna System {METHOD FOR ARRANGING CREST FACTOR REDUCTION DEVICE OF DISTRIBUTED ANTENNA SYSTEM}

The technical idea of the present invention is related to a signal distribution system, and more particularly, to a method of arranging a crest factor reduction (CFR) in a distributed antenna system (DAS).

To reduce the signal peak-to-average power ratio (PAPR), CFR is used a lot. Especially in systems using DPD (Digital Pre-Distorter), CFR is implemented in front of DPD to improve system efficiency.

In the case of the DAS, such CFR is generally implemented in front of the DPD at the remote unit (RU) of the node units constituting the DAS. However, when the number of RUs is large, the CFR may increase the complexity and cost of the RU. Can be. In addition, when multi-band signal processing is required for the RU of the DAS, CFR is required as many as the number of bands, thereby greatly increasing the complexity of the RU.

An object of the present invention is to provide a method for distributing crest factor reduction (CFR) at an optimal position according to each topology type or design method in a distributed antenna system.

According to an aspect of the present invention, there is provided a distributed antenna system including: at least one headend unit configured to receive mobile communication signals from a plurality of base stations; And at least one remote unit communicatively connected with the at least one headend unit, the at least one headend unit receiving the mobile communication signal from the at least one headend unit, and disposed remotely to transmit the mobile communication signal to a terminal within a service coverage area. Including, The at least one remote unit, The signal adding unit for digitally summing mobile communication signals transmitted from the at least one head-end unit and disposed on the rear end of the signal adding unit based on the signal transmission direction Contains the CFR module.

In at least one example embodiment, the at least one remote unit may receive a mobile communication signal transmitted from the at least one headend unit, and separate the band corresponding to a specific mobile communication service band from among the inputted mobile communication signals. It may further include wealth.

In an exemplary embodiment, the signal summing unit may perform digital signal summing on different subband signals in the same mobile communication service band among the signals separated by the band separating unit.

According to another aspect of the present invention, there is provided a distributed antenna system including: at least one headend unit configured to receive mobile communication signals from a plurality of base stations; And at least one remote unit communicatively coupled to the at least one headend unit, the at least one headend unit receiving the mobile communication signal from the at least one headend unit and disposed remotely to send the mobile communication signal to a terminal within a service coverage Including, The at least one remote unit, Group delay equalization processor for performing a group delay equalization process for the mobile communication signals transmitted from the at least one head-end unit and the group delay based on the signal transmission direction And a CFR module disposed at the rear of the equalization processor.

According to embodiments of the inventive concept, in a distributed antenna system, a CFR may be disposed at an optimal position according to each topology type or design method.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.
1 is a view illustrating an example of a topology of a distributed antenna system as one type of a signal distributed transmission system to which the technical spirit of the present invention may 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 may be applied.
FIG. 3 is a diagram illustrating one embodiment of a topology of a distributed antenna system for describing an embodiment according to the inventive concept.
4 is a view for explaining a CFR arrangement method according to an embodiment according to the spirit of the present invention.
FIG. 5 is a diagram illustrating another embodiment of a topology of a distributed antenna system for describing an embodiment according to the inventive concept.
6 is a view for explaining a CFR arrangement method according to another embodiment according to the spirit of the present invention.
7 is a view for explaining a CFR arrangement method according to another embodiment according to the spirit of the present invention.

The technical spirit of the present invention may be variously modified 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 spirit of the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the scope of the technical spirit of the present invention.

In describing the technical idea of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the gist of the technical idea of the present invention, the detailed description thereof will be omitted. In addition, numerals (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" with another component, the one component may be directly connected or directly connected to the other component, but in particular It is to be understood that unless otherwise indicated, there may be connected or connected via another component in the middle.

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

Hereinafter, a description will be given of a distributed antenna system as an application example to which embodiments according to the spirit of the present invention can be applied. However, embodiments of the inventive concept may be similarly or similarly applied to other signal distributed transmission systems such as a base station distributed system in addition to a distributed antenna system.

1 is a diagram illustrating a topology of a distributed antenna system as one type of a signal distribution transmission system to which the technical spirit of the present invention may be applied.

Referring to FIG. 1, a distributed antenna system (DAS) includes a base station interface unit (BIU) 10, a main unit 20, and an expansion node constituting a headend node of a distributed antenna system. (Hub Unit 30), which is an (extention node), and a plurality of Remote Units (RU) 40 disposed at each remote service location. Such a distributed antenna system may be implemented as an analog DAS or a digital DAS, and in some cases, may be implemented as a hybrid thereof (ie, some nodes perform analog processing and others perform digital processing).

However, FIG. 1 illustrates an example of a topology of a distributed antenna system, and the distributed antenna system includes an installation area and an application field (for example, in-building, subway, hospital, Various topologies can be modified in consideration of the specificity of the stadium. For this purpose, the number of BIU 10, MU 20, HUB 30, RU 40 and the connection relationship between the upper and lower ends may also be different from FIG. In addition, in the distributed antenna system, the HUB 20 is utilized when the number of branches to be branched from the MU 20 to the star structure is limited compared to the number of RUs 40 required for installation. Therefore, the HUB 20 may be omitted when only a single MU 20 can adequately cover the number of RUs 40 required for installation or when a plurality of MUs 20 are installed.

Hereinafter, each node and its function in the distributed antenna system, which can be applied to the technical spirit of the present invention, will be described in sequence with reference to the topology of FIG. 1.

The 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. Although FIG. 1 illustrates a case in which a plurality of BTSs 5 are connected to a single BIU 10, the BIU 10 may be provided separately for each service provider, each frequency band, and each sector.

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

If the BIU 10 lowers the high power signal of the BTS 5 to low power and combines each mobile communication service signal to the MU 20, the MU 20 combines and transmits the mobile communication service signal ( Hereinafter, this will be referred to as a relay signal) to distribute each branch. In this case, when the distributed antenna system is implemented as a digital DAS, the BIU 10 may convert a 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) and then digital signal processing to separate the unit to combine. 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 may combine to distribute each relayed signal and distribute it for each branch. .

As described above, the combined relay signal distributed from the MU 20 is passed through the HUB 20 to branch stars (see Branch # 1,…, Branch #k,…, Branch #N in FIG. 1) or RU ( 40), each RU 40 separates the received combined relay signal for each 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, an RF cable is connected between the BTS 5 and the BIU 10 and between the BIU 10 and the MU 20 and an optical cable is connected from the MU 20 to the lower end thereof. However, the signal transport medium between each node can be modified in various ways. For example, the BIU 10 and the MU 20 may be connected through an RF cable, but may also 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 are connected by an optical cable, and the cascaded RU 40 is connected to each other through an RF cable, a twisted cable, and a UTP. It may also be implemented in a way that is connected via a cable or the like. As another example, another example, the RU 40 directly connected to the MU 20 may also be implemented in a manner that is connected via an RF cable, twisted cable, UTP cable and the like.

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

The distributed antenna system may be connected to an external management device, for example, a NMS (Network Management Server or System) 50 through a network. Accordingly, the manager can monitor the status and problems of each node of the distributed antenna system remotely 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 spirit of the present invention may be applied.

Here, the block diagram of FIG. 2 illustrates one implementation of an RU 40 in a digital DAS where node-to-node connectivity is via an optical cable. The block diagram of FIG. 2 illustrates only components related to the 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 may include an optical to electrical converter 50 and a serializer 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 pass, the optical relay signal digitally transmitted through the optical cable is converted into an electrical signal (serial digital signal) by the optical / electric converter 50, and the serial digital signal is parallel digital by the SERDES 44. The digital signal is converted into a signal, and the parallel digital signal is reformatted by the deframer 52 so that the digital signal processor 70 can process the frequency band. The digital signal processor 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 passed through the digital signal processing unit 70 is converted into an analog signal via a digital-to-analog converter 54 constituting the final stage of the digital part 84 based on the signal transmission path. At this time, the analog signal is an IF signal, and is up-converted to an analog signal of the original RF band through the up converter 56. The analog signal (that is, the RF signal) converted into the original RF band as described above is transmitted through a service antenna (not shown) through the PAU 58.

Based on the uplink signal propagation path (ie, reverse path), the RU 40 may include a low noise amplifier (LNA) 68, a down converter 66, and an analog / digital converter (ADC). 64, a digital signal processor (DSP) 70, a framer 62, a SERDES 44, and an electrical to optical converter 60.

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

In addition, although not clearly illustrated in FIG. 2, when the RUs 40 are cascaded to each other, as shown in the example of FIG. 1, the relay signal transmitted from an upper end is transmitted to an adjacent RU of a lower cascaded end. This can be done in the following way. For example, when the optical relay signal digitally transmitted from the upper end is transferred to the adjacent RU of the lower cascaded lower end, the optical relay signal digitally transmitted from the upper end is the optical / electric converter 50-> SERDES 44-. > Deframer 52-> framer 62-> SERDES 44-> pre / optical converter 60 and then to adjacent RUs. This will be clearly understood through FIG. 4 to be described later.

2, the SERDES 44, the deframer 52, the framer 62, and the digital signal processor 70 may be implemented as a field programmable gate array (FPGA). In addition, although the SERDES 44 and the digital signal processor (DSP) 70 are shared in the downlink and uplink signal transmission paths in FIG. 2, they may be provided separately for each path. In addition, although the optical / electric converter 50 and the electrical / optical converter 60 are shown separately in FIG. 2, this is a single optical transceiver module (eg, a single small form factor pluggable (SFP) (FIG. 2). Reference numeral 82 of FIG. 2).

In the above, with reference to FIGS. 1 and 2, one type of topology of a distributed antenna system and one configuration example of an RU have been described. In particular, FIG. 2 illustrates the RU in the digital DAS digitally transmitted through the transmission medium. However, the technical idea of the present invention can be applied to various other applications.

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

Embodiment 1-CFR Placement in HEU (M): HUB (1): RU (N) Topology

As a first embodiment, in a distributed antenna system, in a topology of multiple (M) HEUs, a single HUB, and multiple (N) RUs (see the topology of FIG. 3 or FIG. 5), CFR is implemented on the HUB side. This can lower signal degradation and RU complexity.

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

In the topology of FIG. 3 or 5, each HEU (100A, 100B, 100C) is a baseband or intermediate frequency band for the mobile communication signal of a plurality of mobile communication service bands received from a plurality of BTS And convert the digital signal to the HUB 200 by performing a 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, respectively, via a transmission medium. In the example of FIG. 3, each of the HEUs 100A, 100B, and 100C receives a WCDMA band signal, an LTE band signal, and an LTE-A band signal from three BTSs, respectively. In addition, it is assumed that each HEU 100A, 100B, 100C receives a mobile communication signal of a different mobile communication operator. In FIG. 3, it is assumed that one HEU and one mobile communication provider are matched one-to-one, but the present invention is not limited thereto. On the other hand, in the topology of FIG. 5, each of the HEUs 100A, 100B, and 100C receives different sector-specific signals within a specific mobile communication service band through a transmission medium.

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

Hereinafter, with reference to FIG. 4 based on the topology of FIG. 3 and with reference to FIG. 5 based on the topology of FIG. 5, a CFR arrangement method according to an embodiment of the inventive concept will be described in order. do.

FIG. 4 is a diagram illustrating components constituting a mixing process stage related to a CFR placement position description according to an embodiment of the inventive concept among digital parts implemented in a HUB or HEU. However, in the present description, since the HEU (M): HUB (1): RU (N) topology of FIG. 3 is assumed, the components of FIG. 4 are implemented in the HUB according to an embodiment of the inventive concept.

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

The signal branch 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 (see reference numeral (A) in FIG. 4) of the mobile communication service provider A is input to the HUB 200 from the HEU of 100A, and the mobile service provider B moves from the HEU of the reference code 100B. A communication signal (see (B) in FIG. 4) is input to the HUB 200, and a mobile communication signal (see (C) in FIG. 4) of the mobile communication service provider C is connected to the HUB (HEU). Assume a case of inputting 200). At this time, the signal input to the HUB 200 for each mobile communication provider may include a mobile communication signal of the WCDMA band, LTE band, LTE-A band.

The mobile communication signal for each mobile communication provider uses a digital signal for each service band (the digital filter for separating the WCDMA band, the digital filter for separating the LTE band, and the LTE-A band through the signal branch unit 1010). Digital filter for separation).

The band separator 1020 includes a digital filter for each service band, as described above, to separate only a signal corresponding to the service band. 4, the mobile communication signal (A) of the mobile communication provider A, the mobile communication signal (B) of the mobile communication provider B, and the mobile communication signal (C) of the mobile communication provider C are assigned to the digital filter for each service band. Band (a1) denotes a signal of the WCDMA band of the mobile communication signal (A) of the mobile communication provider A, and reference numeral (b1) denotes a signal of the mobile communication signal (B) of the mobile communication provider B A signal of the WCDMA band, and reference numeral (c1) denotes a signal of the WCDMA band of the mobile communication signal (C) of the mobile communication provider C. In the same manner as the above, reference numerals (a2), (b2), and (c2) refer to signals of an LTE band among mobile communication signals of respective mobile operators, and reference numerals (a3), (b3), and (c3) Means a signal of the LTE-A band of the mobile communication signals of each mobile communication provider.

As described above, when the signal for each mobile communication provider passes through the band separation unit 1020, as shown by reference numeral 1020A of FIG. 4, each subband within the same mobile communication service band (Sub-band 1, Sub-band). 2, sub-band 3) signal can be extracted. Here, Sub-band 1 conceptually illustrates a frequency band used by the mobile communication service provider A in the process of providing a specific mobile communication service, and Sub-band 2 is a mobile communication service provider B in the process of providing a specific mobile communication service. The frequency band to be used is conceptually illustrated, and Sub-band 3 conceptually illustrates the frequency band to be used by the mobile communication provider C in the process of providing a specific mobile communication service.

As described above, each subband signal separated by the same mobile communication service band through the band separation unit 1020 is input to the signal summing unit 1030. In an embodiment of the inventive concept, the signal summing unit 1030 may first digitally summing different subband signals in the same mobile communication service band input through the band separating unit 1020. (Refer to reference numeral 1032 in FIG. 4). The band-specific signals thus summed are finally digitally added (see reference numeral 1034 in FIG. 4).

As described above, when a plurality of subband signals exist in the same mobile communication service band, and the digital signal summation is performed in the HUB 200, the CFR processing is performed after the digital signal summation is minimized to minimize signal degradation. can do. Therefore, in FIG. 4, the CFR module 1040 is disposed behind the signal adding unit 130.

In the above example, the subband signal is added for each of the same mobile communication service bands in the forward mobile communication signals received from the plurality of HEUs, but the CFR module also adds the final signal in the case of various digital signal addition cases. However, it may be arranged at the rear end.

FIG. 6 is a diagram illustrating components constituting a mixing process stage related to a CFR placement position description according to another embodiment of the inventive concept among digital parts implemented in a HUB or HEU. However, in the present description, since the HEU (M): HUB (1): RU (N) topology of FIG. 5 is assumed, the components of FIG. 6 are implemented in the HUB according to an embodiment of the inventive concept.

Referring to FIG. 6, the mixed processing stage implemented in the digital part of the HUB 200 includes a signal swap unit 1050. In this case, the CFR module 1040 may include a signal swap unit (B) to minimize signal degradation. 1050) may be disposed at the rear end.

As shown in FIG. 5, when a plurality of HEUs 100A, 100B, and 100C receive different sector signals within the same mobile communication service band and transmit them to the HUB 200, 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 which performs signal swap processing. Referring to FIG. 6, the input signal for each sector (see sector A, sector B, and sector C of FIG. 6) is subjected to the frequency band swap processing by the signal band swap processing unit 1052, and the sum of the swapped signals is performed. The CFR module 1040 is disposed at the rear end of the configuration (refer to the configuration portion 1054 of FIG. 6).

Second Embodiment-CFR Placement in HEU (1): RU (N) or HEU (1): HUB (1): RU (N) Topology

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, a plurality (N) RUs, the CFR is applied to the MU side. Implementation can reduce signal degradation and RU complexity.

At this time, the HEU is connected to a plurality of base stations or a single / multiple operators in one, it can be connected in a star or / and cascade structure with N RU or directly through a single HUB. In this case, when transmitting the signal to the HUB or directly to the N RUs, the HEU may transmit the digital signal after adding the mobile communication signal received for each base station digitally. In this case, since the digital signal summation is finally made in the HEU, the CFR is preferably implemented in the HEU. In this case, as described above, the CFR module is preferably disposed at the rear of the signal adding unit (see reference numeral 1030 of FIG. 4). 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 of the signal swap unit (see reference numeral 1050 of FIG. 6).

Example 3-CFR Placement in RU

As described above through the above embodiments, when there are a plurality of subband signals in the same mobile communication service band, separation and summation of signals for each band are required, and in this case, CCDF deterioration when the CFR is performed after signal summation processing. Can be prevented.

For example, if the final signal sum is calculated in HEU or HUB, CFR may be implemented in HEU or HUB, but in some cases (for example, due to reduced transmission capacity, etc.) May occur. Therefore, in this case, the CFR may be implemented after the signal summing unit (refer to reference numeral 1030 of FIG. 4) implemented in the digital part on the RU side. This has been described in detail above with reference to FIG. 4, and a redundant description will be omitted.

In addition, there is a case where disposing a CFR in the RU can minimize signal degradation, which will be described with reference to FIG. 7. 7 illustrates a case in which a group delay equalization processing function is implemented in the digital part of the RU. The group delay equalization process may be used to equalize delays between a plurality of subband signals in the same mobile communication service band. For example, in case of an LTE signal using the OFDM scheme, it is important to equalize delays between subband signals. To this end, the digital part of the RU may include a signal branch 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 based on the signal transmission direction. Therefore, signal degradation can be minimized.

In the above described with reference to various embodiments according to the technical idea of the present invention, those skilled in the art without departing from the technical spirit of the present invention described in the claims below It will be readily understood that various technical ideas can be modified and changed.

Claims (6)

At least one headend unit for receiving mobile communication signals from a plurality of base stations; And
At least one remote unit communicatively coupled to the at least one headend unit and receiving the mobile communication signal from the at least one headend unit and disposed remotely to transmit the mobile communication signal to a terminal within service coverage; Including,
The at least one remote unit includes a group delay equalization processor that performs group delay equalization processing on mobile communication signals transmitted from the at least one headend unit and a rear end of the group delay equalization processor based on a signal transmission direction. Include deployed CFR modules,
The at least one remote unit further includes a band splitter configured to receive a mobile communication signal transmitted from the at least one headend unit and separate only a signal corresponding to a specific band from the input mobile communication signals. .
The method of claim 1,
The group delay equalization processor,
And equalizing a delay between a plurality of subband signals in a same mobile communication service band among signals separated by the band separator.
The method of claim 1,
The at least one remote unit,
And a signal branch unit for branching a signal such that mobile communication signals transmitted from the at least one headend unit are input to a digital filter for each communication band in the band separating unit.
In the remote unit,
A group delay equalization processor configured to perform group delay equalization processing on mobile communication signals transmitted from a plurality of base stations through at least one headend unit; And
A CFR module disposed at a rear end of the group delay equalization processor based on a signal transmission direction,
The remote unit further includes a band separation 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.
The method of claim 4, wherein
The group delay equalization processor,
And equalizing a delay between a plurality of subband signals in the same mobile communication service band among the signals separated by the band separator.
The method of claim 4, wherein
The remote unit,
And a signal branch unit for branching a signal such that mobile communication signals transmitted from the at least one headend unit are input to a digital filter for each communication band in the band separating unit.

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