KR101877269B1 - Device for controlling gain of each band of mobile telecommnication signal - Google Patents

Abstract

A digital filter for filtering an input mobile communication signal according to a predetermined passband and applying a band-specific filter coefficient set for each of a plurality of band bands within the pass band to output a mobile communication signal having a gain adjusted for each of the band bands; And a controller for generating the band-specific filter coefficient to be applied to the digital filter in accordance with a target gain targeted for each signal of the division band.

Description

TECHNICAL FIELD [0001] The present invention relates to a gain control device for a mobile communication signal,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

In a mobile communication system, a mixed signal composed of different mobile communication service signals, a plurality of sub-band signals in the same mobile communication service, a plurality of FA (Frequency Allocation) signals, In many cases, the gain control of the mixed signal is often required for each mobile communication service, for each subband, for each FA, or for each provider.

In the above-described case, in the case of the related art, since the mixed signals are subjected to signal separation for each frequency band, and the gain control is separately performed for the separated signals, There is a problem that system complexity increases.

Therefore, a method capable of controlling the gain of each band for the mixed signal with low system complexity is required.

The present invention provides an apparatus capable of controlling gain of a mixed signal input to a band without signal separation and individual gain control for each band for a mixed signal in a band.

According to an aspect of the present invention, there is provided a mobile communication system, comprising: a mobile communication unit for filtering an input mobile communication signal according to a predetermined passband, applying a band-specific filter coefficient set for each of a plurality of band segments in the passband, A digital filter for outputting a communication signal; And a controller for generating the band-specific filter coefficient to be applied to the digital filter in accordance with a target gain targeted for each signal of the division band.

According to an embodiment, the controller may generate the band-specific filter coefficient corresponding to a ratio between target gains for each signal of the segment band.

In an embodiment of the present invention, the plurality of division bands includes a plurality of sub-bands, a plurality of frequency allocation (FA) bands in a service band according to the same mobile communication service, a frequency band allocated to a plurality of different carriers And a service band according to a plurality of mobile communication services accommodated in a passband of the digital filter.

The signal processor may further include a signal attenuator disposed at a front end of the digital filter with respect to a signal transmission path for attenuating a signal level of a mobile communication signal input to the digital filter in order to prevent saturation of the digital filter, have.

In one embodiment, when the signal level of the mobile communication signal to be input to the digital filter is equal to or greater than a predetermined threshold level at which the digital filter is to be saturated, the control unit activates the attenuation operation by the signal attenuator, Lt; / RTI > and / or < / RTI >

The mobile communication apparatus according to one embodiment of the present invention may be configured such that a mobile communication signal output from the digital filter is applied to a mobile communication signal output from the digital filter by applying the same gain value to a mobile communication signal output from the digital filter, And a gain adjustment unit for adjusting the target gain to reach the target gain.

In one embodiment, the control unit generates a single control gain value for causing the mobile communication signal output from the digital filter to reach the target gain for each of the band segments, and transmits the single control gain value to the gain adjuster,

The gain adjuster may vary the gain value based on the control gain value transmitted from the controller.

According to the embodiment of the present invention, it is possible to control the gain for each band for the mixed signal inputted without dividing the signal into individual bands and controlling the individual gains with respect to the mixed signals in the bands, thereby reducing system complexity .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a topology of a distributed antenna system according to one embodiment of the present invention. FIG.
2 is a block diagram of an embodiment of a remote unit in a distributed antenna system to which the present invention may be applied;
FIG. 3 is a view for explaining an associated technique as compared with a band-specific gain control method according to an embodiment of the present invention; FIG.
FIG. 4 is a view for explaining a gain adjustment method for each band according to an embodiment of the present invention; FIG.
5 is a block diagram of an embodiment of a band-specific gain adjustment apparatus according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, numerals (e.g., first, second, etc.) used in the description of the present invention are merely an identifier for distinguishing one component from another.

Also, in this specification, when an element is referred to as being "connected" or "connected" with another element, the element may be directly connected or directly connected to the other element, It should be understood that, unless an opposite description is present, it may be connected or connected via another element in the middle.

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

Hereinafter, a specific node unit (head end unit, hub unit, remote unit, etc.) in the distributed antenna system will be described as an application to which the band gain adjustment apparatus according to the embodiment of the present invention can be applied. However, the embodiments of the present invention can also be applied to other node-specific distributed units such as a base station distributed system, etc. in addition to a distributed antenna system in the same or similar manner in a specific node unit (e.g., a head end and a remote radio head (RRH) Applicable. It goes without saying that the band-specific gain adjustment apparatus according to the embodiment of the present invention is also applicable to a digital RF repeater.

FIG. 1 is a diagram illustrating an example of a topology of a distributed antenna system as one embodiment of a signal distribution transmission system to which the present invention can be applied.

1, a distributed antenna system (DAS) includes a base station interface unit (BIU) 10, a main unit (MU) 20, (Hub Unit) 30, which is an extension node, and a plurality of RUs (Remote Unit) 40, which are arranged at remote service locations. 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 mixed type (i.e., some nodes perform analog processing and the remaining nodes perform digital processing).

1 shows an example of a topology of a distributed antenna system, and a distributed antenna system may be used in an installation area and an application field (for example, an in-building, a subway, a hospital, Stadiums, etc.), various topology modifications are possible. In this case, the number of BIU 10, MU 20, HUB 30, RU 40, and the connection relationship of the upper and lower ends of the BIU 10, the HUB 30, and the RU 40 may differ from those of FIG. Also, 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 the number of the RUs 40 required to be installed can be sufficiently satisfied even with a single MU 20, or when a plurality of MUs 20 are installed.

Hereinafter, with reference to the topology of FIG. 1, each node in the distributed antenna system applicable to the present invention and its function will be described in turn.

A Base Station Interface Unit (BIU) 10 serves as an interface between a Base Station Transceiver System (BTS) such as a base station and an MU 20 in a distributed antenna system. In FIG. 1, a plurality of BTSs are connected to a single BIU 10, but the BIU 10 may be separately provided for each service provider, for each frequency band, and for each sector.

Generally, since the RF signal transmitted from the BTS is a high power signal, the BIU 10 generally transmits a RF signal of a high power level to the MU 20 And transfers it to the MU 20. 1, the BIU 10 receives a signal of a mobile communication service for each frequency band (or for each service provider, sector) as shown in FIG. 1, combines the signals, ), As shown in FIG.

If the BIU 10 lowers the high power signal of the BTS to a low power and then combines the mobile communication service signals and transmits them to the MU 20, the MU 20 combines the received mobile communication service signals Relay signal ") for each branch. In this case, when the distributed antenna system is implemented as a digital DAS, the BIU 10 includes a unit that performs a function of converting a high-power RF signal of the BTS into a low-power RF signal, and a unit that performs an IF (Intermediate Frequency) And converted into a unit for performing a digital signal process and combines them. Alternatively, if the BIU 10 only performs a function of lowering the high power signal of the BTS to low power, the MU 20 may combine the transmitted relay signals and distribute the relay signals for each branch.

As described above, the combined relay signal distributed from the MU 20 is transmitted to the RU 40 via the HUB 20 with respect to each branch (see Branch # 1, ... Branch #k, ... Branch #N in FIG. 1) And each RU 40 separates the combined combined relay signals by frequency bands 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 in its service coverage through a service antenna. The specific functional configuration of the RU 40 will be described later in detail with reference to FIG.

1, a case where an RF cable is connected between the BTS and the BIU 10 and a case where the BIU 10 and the MU 20 are connected by the RF cable, and all the connections from the MU 20 to the lower end are connected by the optical cable, The signal transport medium between each node can also be modified in various ways. 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, an optical cable is connected between the MU 20 and the HUB 30 and an RU 40 directly connected to the MU 20, and an RF cable, a twisted cable, a UTP Cable, or the like. As another example, in another example, the RU 40 directly connected to the MU 20 may also be implemented in such a manner that they are connected via an RF cable, a twisted cable, a UTP cable, or the like.

However, the following description will be made with reference to Fig. Therefore, in this embodiment, the MU 20, the HUB 30, and the RU 40 may include optical transceiver modules for all-optical conversion / photoelectric conversion, and when interconnecting nodes with a single optical cable, Wavelength Division Multiplexing (WDM) devices. This can be clearly understood from the functional description of the RU 40 in FIG. 2, which will be described later.

The distributed antenna system can be connected to an external management apparatus (NMS (Network Management Server or System) in FIG. 1 via the network.) Accordingly, the manager can remotely monitor the status and problem of each node of the distributed antenna system through the NMS And can 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 present invention may be applied.

Here, the block diagram of FIG. 2 illustrates one implementation of an RU 40 within a digital DAS in which the inter-node connection is via an optical cable. The block diagram of FIG. 2 shows only the components related to the function of providing the service signal to the terminal in the service area through the forward path and processing the terminal signal received from the terminal in the service area through the reverse path.

Herein, the node unit to which the band gain control apparatus according to the embodiment of the present invention can be applied may be various other than the remote unit to be described later, such as the RRH in the headend, the HUB, and the distributed case of the base station. Hereinafter, a remote unit in the distributed antenna system will be assumed for convenience and concentration of explanation.

Referring to FIG. 2, the RU 40 includes an optical to electrical converter 50, a serializer (SERDES) 50, and a serial-to-serial converter A deserializer 44, a deframer 52, a digital signal processor (DSP) 70, a digital / analog converter (DAC) 54, an up converter 56, (Amplification Unit) 58.

Thus, in the forward path, the optical relaying signal digitally transmitted through the optical cable is converted into an electric signal (serial digital signal) by the optical / electrical converter 50, and the serial digital signal is converted by the SERDES 44 into parallel digital And the parallel digital signal is reformatted by the de-framer 52 so that the digital signal processor 70 can process the 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 with respect to the relay signal. The digital signal passed through the digital signal processing unit 70 is converted into an analog signal via the digital / 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. In this way, the analog signal converted into the original RF band (i.e., the RF signal) is transmitted through the PAU 58 and transmitted through the service antenna (not shown).

The RU 40 includes a Low Noise Amplifier (LNA) 68, a down converter 66, an analog-to-digital converter (ADC) 68, A digital signal processor (DSP) 70, a framer 62, a SERDES 44, and an electrical to optical converter 60. The digital signal processor (DSP)

Thus, in the reverse path, the RF signal (i.e., the terminal signal) received via the service antenna (not shown) from the user terminal (not shown) in the service coverage is low noise amplified by the LNA 68, 66, and the converted IF signal is converted into a digital signal by the analog-to-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 into a format suitable for digital transmission through the framer 62 and converted into a serial digital signal by the SERDES 44, And is transmitted to the upper end through the optical cable.

Although not clearly shown in FIG. 2, when the RUs 40 are cascade-connected to each other as in the example of FIG. 1, when a relay signal transmitted from an upper end is transmitted to a neighboring RU of a cascaded lower end The following method can be used. For example, when an optical relay signal digitally transmitted from an upper stage is transmitted to a neighboring RU of a lower stage cascaded, the optical relay signal digitally transmitted from the upper stage is transmitted to the optical / electrical converter 50 -> SERDES 44 - The descrambler 52, the framer 62, the SERDES 44, and the photodetector 60 in that order. This can be clearly understood from FIG. 4, which will be described later.

2, the SERDES 44, the de-framer 52, the framer 62, and the digital signal processor 70 may be implemented by FPGA (Field Programmable Gate Array). Also, although the SERDES 44 and the digital signal processor (DSP) 70 are shown as shared in the downlink and uplink signal propagation paths in FIG. 2, they may be separately provided for each path. 2, a separate optical transceiver module (e.g., a single SFP (Small Form Factor Pluggable) (also referred to as a " SFP " 2, reference numeral 82)).

1 and 2, each node unit in the topology of one type of the distributed antenna system has been described as an application example to which the band gain adjustment apparatus according to the embodiment of the present invention can be applied. Hereinafter, with reference to FIG. 3 to FIG. 5, a band-specific gain adjustment apparatus according to an embodiment of the present invention will be described.

FIG. 3 is a view for explaining an associated technique in contrast to a band-specific gain control scheme according to an embodiment of the present invention.

Referring to FIG. 3, when the band-specific mixed signal (see FIG. 3 (a)) is input, the band-dependent gain control method according to the related art divides the mixed signal into band- (b-2) and (c-2) in FIG. 3), and the individual gain-adjusted band-by-band signals are re-summed (See Fig. 3 (d)). Therefore, a filter (see Filter 1 and Filter 2 in FIG. 3) and a gain adjuster (see Gain 1 and Gain 2 in FIG. 3) must be provided for each band, and a signal adder .

Unlike the above, in the embodiment of the present invention, the signal separation process as described above, the individual gain adjustment process of each band, and the gain adjustment of each band without performing the process of summing the gain-controlled band- . FIG. 4 is a conceptual diagram illustrating a method of adjusting gain for each band according to an embodiment of the present invention. Here, FIG. 4 is a view for explaining a gain adjustment method for each band according to an embodiment of the present invention.

Referring to FIG. 4, according to an embodiment of the present invention, band-by-band gain control of the mixed signal (see the A-band signal and the B-band signal in FIG. 4) is performed by the signal separation, individual gain control, This is due to the adjustment of the band-specific filter coefficients in the digital filter without performing signal summation. That is, in the embodiment of the present invention, by applying a band-specific filter coefficient for applying a different gain value to a band-by-band signal included in a mixed signal to a digital filter, Respectively. Hereinafter, a concrete configuration for implementing the band-specific gain control scheme of FIG. 4 will be described with reference to FIG.

In this specification, each division band signal included in the mixed signal is divided into a plurality of sub-bands, a plurality of FA (Frequency Allocation) bands in a service band according to the same mobile communication service, And a service band according to different mobile communication services accommodated in a passband of the digital filter. Hereinafter, for convenience and concentration of explanation, it is assumed that mixed signals include a plurality of different business signals in the same mobile communication service band.

5 is a block diagram of an embodiment of a band-specific gain control apparatus according to an embodiment of the present invention.

Referring to FIG. 5, the band-specific gain control apparatus according to an embodiment of the present invention includes a digital filter 110 and a controller 140. The band-specific gain control apparatus further includes a signal attenuator 120 at the front end of the digital filter 110 and a gain control unit 130 at the rear end of the digital filter 110, . The above components may also be embodied in a digital part within a particular node as described above with respect to FIGS. 1 and 2, according to an embodiment.

The digital filter 110 filters the input mobile communication signal according to a predetermined passband. Also, according to an embodiment of the present invention, the digital filter 110 applies a band-specific filter coefficient set for each of a plurality of band bands in the pass band, and outputs a mobile communication signal whose gain is adjusted for each band band . That is, the digital filter 110 applies a filter coefficient set for each band to the mobile communication signal of the input mixed band, and when the mobile communication signal of the input mixed band is filtered, Output. This can be easily understood through the drawings and the description of FIG.

When the mobile communication signal of the mixed band is outputted through the digital filter 110 as described above, the controller 140 applies the signals according to the signals of the divided bands included in the mixed signal, (See filter coefficient generation unit 146 in FIG. 5), and controls such band-specific filter coefficients to be applied to the digital filter 110. FIG.

Of course, if it is the case that the division band of the mixed signal input to the digital filter 110 and the gain of each division band at that time are fixed, the control process through the controller 140 may be omitted have. In this case, it is not necessary to change the band-specific filter coefficient at the initial setting. However, in other cases (that is, when the input band of the mixed signal is flexible or the gain of each band is to be changed flexibly), it is necessary to adaptively change the band-specific filter coefficient according to the signal of the corresponding band , Which can be achieved through the process of generating the filter coefficient for each band by the control unit 140 described above.

In order to adaptively generate the band-specific filter coefficients, the controller 140 may refer to a target gain target of each of the band-by-band signals included in the mixed signal. For example, when the mixed signal includes signals of two different providers and the target gains are set differently for each provider signal, the control unit 140 may divide the divided band (i.e., , Each service band of the operator signal). More specifically, the control unit 140 can generate band-specific filter coefficients corresponding to the ratio between the target gains of the individual carrier signals. This will be more clearly understood through numerical examples in the following description.

The signal attenuation unit 120 may be disposed before the digital filter 110 based on the signal transmission path to attenuate the signal level of the mobile communication signal to be input to the digital filter 110 in advance. In the embodiment of the present invention, the signal attenuator 120 outputs a digital signal to the digital filter 110 when the signal level input to the digital filter 110 exceeds a normal allowable level for normal filtering by the digital filter 110 and band- And may be optionally provided to prevent saturation of the filter 110. Therefore, when the signal level input to the digital filter 110 is within the tolerance level or there are other commercially available components that attenuate within the tolerance level before the signal is input into the digital part, the signal attenuator 120 is omitted It can be done.

Also, according to the embodiment, the attenuation operation and / or the signal attenuation level by the signal attenuation unit 120 can be controlled by the control unit 140. [ For example, the control unit 140 may include a signal attenuator 120, and the control unit 140 may include a signal attenuator (not shown) based on the monitoring information about the input signal level (which may be collected by the input level verifier 142 in FIG. 5) 120 can be controlled to be activated or deactivated. As another example, the control unit 140 may control the signal attenuator 120 to operate at an attenuation level that is equal to or greater than the threshold value when the input signal level exceeds the tolerance level (i.e., the specific threshold level) have. In this case, the signal attenuator 120 may be implemented as a variable attenuator.

Also, according to the embodiment, a gain adjusting unit 130 may be additionally provided at the rear end of the digital filter 110, as shown in FIG. The gain control unit 130 is disposed at the rear end of the digital filter 110 on the basis of the signal transmission path so that the mobile communication signals of the mixed band output from the digital filter 110 are divided into the target gains Can be achieved.

Hereinafter, an example will be described. The signal of the mixed band inputted to the digital filter 110 is a signal of the A band of the first carrier and a signal of the B band of the second carrier similarly to FIG. 4, Lt; / RTI > dB. It is also assumed that the final target level of the signal of the A band of the first carrier is 3N dB and the final target level of the signal of the B band of the second carrier is 2N dB. In the above case, when the filtering by the digital filter 110 is completed, the controller 140 maintains the level of the A-band signal at N dB and the level of the B-band signal at N * (2/3) dB , The filter coefficient for each band can be generated. According to the above example, the signal for each band passing through the digital filter 110 is lower than the original target level. Therefore, in this case, the gain adjustment unit 130 can give a gain of three times, so that the signal for each band can finally reach the target levels 3N dB and 2N dB.

However, the gain control unit 130 may be omitted according to the implementation method. For example, there is a case where a separate gain control means such as PA (Power Amplification) is present at the stage after the digital part based on the signal transmission path. In contrast, in the digital transmission system, if there is no separate gain control means behind the digital filter 110, the gain control unit 130 may be required.

At this time, the gain value to be applied by the gain adjusting unit 130 may be set to a fixed single value, but may be transmitted from the controller 140. For example, the control unit 140 controls the signal level of each band of the mobile communication signal of the mixed band inputted to the digital filter 110, the gain control information of each band by the digital filter 110, The control gain calculator 144 calculates a single gain value to be applied to the gain controller 130 by comparing at least one of the output signal levels of each band and the target gains of the respective bands, , And the calculated gain value may be applied to the gain adjustment unit 130. [

As described above, according to the embodiment of the present invention, it is possible to control the gain of each mixed band signal inputted without dividing the signal into individual bands and controlling the individual gains with respect to the mixed signals in the bands. There is an effect.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims And changes may be made without departing from the spirit and scope of the invention.

110: Digital filter
140:
142: input level checking unit
144: Control gain calculating section
146: Filter coefficient generating unit

Claims (7)

A digital filter for filtering an input mobile communication signal according to a predetermined passband and applying a filter coefficient set for each of a plurality of frequency bands in the passband to output a mobile communication signal having a gain adjusted for each of the frequency bands, Wherein the filter coefficient is a filter coefficient capable of applying a different gain value to the signal for each of the division bands;
A control unit for generating the filter coefficient to be applied to the digital filter in accordance with a target gain targeted for each signal of the division band; And
A mobile communication signal output from the digital filter is applied to a mobile communication signal output from the digital filter, and the mobile communication signal output from the digital filter is applied to the target gain A gain adjusting unit for adjusting a gain of the gain adjusting unit;
, ≪ / RTI &
Wherein the control unit generates the band-specific filter coefficient corresponding to a ratio between target gains for each of the divided bands, and controls the mobile communication signal output from the digital filter to reach the target gain for each of the band- And outputs the single control gain value to the gain controller,
The gain control unit may vary the gain value based on the control gain value transmitted from the control unit,
Wherein the plurality of division bands includes a plurality of sub-bands, a plurality of FA (Frequency Allocation) bands, a frequency band allocated to a plurality of different carriers, And a service band corresponding to a plurality of mobile communication services accommodated in the pass band.
delete delete The method according to claim 1,
And a signal attenuator disposed at a front end of the digital filter with respect to a signal transmission path for attenuating a signal level of a mobile communication signal input to the digital filter to prevent saturation of the digital filter, .
5. The method of claim 4,
Wherein the controller is configured to control the attenuation operation by the signal attenuator and the attenuation level by the signal attenuator when the signal level of the mobile communication signal to be input to the digital filter is equal to or greater than a predetermined threshold level at which the digital filter is saturated, Band gain control unit.
delete delete

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