U.S. patent application number 15/893132 was filed with the patent office on 2018-06-21 for headend device of distributed antenna system and signal processing method thereof.
This patent application is currently assigned to SOLiD, INC.. The applicant listed for this patent is SOLiD, INC.. Invention is credited to Bong Cheol Na, Yeong Shin Yeo.
Application Number | 20180176867 15/893132 |
Document ID | / |
Family ID | 55746823 |
Filed Date | 2018-06-21 |
United States Patent
Application |
20180176867 |
Kind Code |
A1 |
Yeo; Yeong Shin ; et
al. |
June 21, 2018 |
HEADEND DEVICE OF DISTRIBUTED ANTENNA SYSTEM AND SIGNAL PROCESSING
METHOD THEREOF
Abstract
A headend device includes a spectrum analysis unit configured to
analyze a frequency spectrum of a plurality of base station signals
to detect characteristic information of the plurality of the base
station signals, a control unit configured to generate a control
signal to control a power of the plurality of the base station
signals on the basis of the characteristic information detected,
and a plurality of RF units configured to receive at least one of
the plurality of the base station signals and adjust the power of
the base station signals received according to the control signal
and output the power-adjusted base station signals.
Inventors: |
Yeo; Yeong Shin;
(Gwangmyeong-si, KR) ; Na; Bong Cheol; (Anyang-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOLiD, INC. |
Seongnam-si |
|
KR |
|
|
Assignee: |
SOLiD, INC.
Seongnam-si
KR
|
Family ID: |
55746823 |
Appl. No.: |
15/893132 |
Filed: |
February 9, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14411487 |
Dec 26, 2014 |
9900847 |
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15893132 |
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PCT/KR2014/009688 |
Oct 15, 2014 |
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14411487 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/228 20130101;
H04L 43/18 20130101; H04B 10/25753 20130101; H04W 52/245 20130101;
H04B 7/2609 20130101; H04B 17/327 20150115; H04B 7/04 20130101 |
International
Class: |
H04W 52/22 20090101
H04W052/22; H04W 52/24 20090101 H04W052/24; H04L 12/26 20060101
H04L012/26; H04B 17/327 20150101 H04B017/327; H04B 10/2575 20130101
H04B010/2575 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2014 |
KR |
10-2014-0138465 |
Claims
1. A transmission resource management sub-system of a distributed
antenna system, the sub-system comprising at least one processor to
implement: an analysis unit configured to analyze a plurality of
base station signals inputted to the distributed antenna system to
detect bandwidths of the plurality of base station signals; and a
control unit configured to calculate a proportional relation
between the bandwidths of the plurality of base station signals,
and generate a control signal for controlling power levels of the
plurality of base station signals based on the proportional
relation.
2. The transmission resource management sub-system of claim 1,
wherein the control signal is a signal for controlling the power
levels of the plurality of base station signals so that the power
levels of the plurality of base station signals correspond to a
power level of a base station signal having a minimum bandwidth
among the plurality of base station signals in accordance with the
proportional relation.
3. The transmission resource management sub-system of claim 1,
wherein the bandwidths of the plurality of base station signals are
channel bandwidths of the plurality of base station signals.
4. The transmission resource management sub-system of claim 1,
wherein at least two of the plurality of base station signals are
signals complying with different communication standards.
5. The transmission resource management sub-system of claim 1,
wherein the analysis unit and the control unit are integrated into
a headend device of the distributed antenna system.
6. The transmission resource management sub-system of claim 5,
wherein the headend device is configured to generate power-adjusted
base station signals by adjusting the power levels of the plurality
of base station signals based on the control signal, generate a
combined signal by combining the power-adjusted base station
signals, and output the combined signal.
7. The transmission resource management sub-system of claim 5,
wherein the analysis unit receives the plurality of base station
signals from the headend device of the distributed antenna
system.
8. The transmission resource management sub-system of claim 1,
wherein the analysis unit receives the plurality of base station
signals from a plurality of base stations.
9. A transmission resource management sub-system of a distributed
antenna system, the sub-system comprising at least one processor to
implement: an analysis unit configured to analyze a plurality of
base station signals inputted to the distributed antenna system to
detect input power values and a number of channels of the plurality
of base station signals; and a control unit configured to calculate
a normalized factor using a sum of the input power values of the
plurality of base station signals and a sum of the number of
channels of the plurality of base station signals, calculate power
adjustment values for each of the plurality of base station signals
using the normalized factor, and generate a control signal for
controlling power levels of the plurality of base station signals
to correspond to the power adjustment values.
10. The transmission resource management sub-system of claim 9,
wherein control unit calculates the normalized factor by dividing
the sum of the input power values of the plurality of base station
signals by the sum of the number of channels of the plurality of
base station signals.
11. The transmission resource management sub-system of claim 9,
wherein the control unit calculates the power adjustment values for
each of the plurality of base station signals by multiplying the
input power of the plurality of base station signals by the
normalized factor.
12. The transmission resource management sub-system of claim 9,
wherein at least two of the plurality of base station signals are
signals complying with different communication standards.
13. The transmission resource management sub-system of claim 9,
wherein the analysis unit and the control unit are integrated into
a headend device of the distributed antenna system.
14. The transmission resource management sub-system of claim 13,
wherein the headend device is configured to generate power-adjusted
base station signals by adjusting the power levels of the plurality
of base station signals based on the control signal, generate a
combined signal by combining the power-adjusted base station
signals, and output the combined signal.
15. The transmission resource management sub-system of claim 13,
wherein the analysis unit receives the plurality of base station
signals from the headend device of the distributed antenna
system.
16. The transmission resource management sub-system of claim 9,
wherein the analysis unit receives the plurality of base station
signals from a plurality of base stations.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The application is a Continuation of application Ser. No.
14/411,487 filed Dec. 26, 2014, which is a Continuation-in-part of
PCT International Application No. PCT/KR2014/009688, filed Oct. 15,
2014, which claims priority to Korean Patent Application No.
10-2014-0138465 filed on Oct. 14, 2014, the contents of all of
which are incorporated herein by reference in their entirety.
TECHNICAL FIELD
[0002] The inventive concept relates to a headend device of a
distributed antenna system and a signal processing method thereof,
and more particularly, to a headend device of a distributed antenna
system which is capable of efficiently managing a limited
transmission resource of a distributed antenna system, and a signal
processing method thereof.
BACKGROUND ART
[0003] In general, with development of mobile communication, use
patterns of and demands for a communication device of users have
been diversified. Users wish to perform communication without time
and space restriction. However, an output from a base station is
restricted, and thus, a shadow area may exist due to the location
of a base station or the topography of an area. In order to
eliminate the shadow area, a distributed antenna system is
used.
[0004] The distributed antenna system includes a headend device
coupled to the base station and a remote device coupled to the
headend device through an optical cable. The distributed antenna
system is installed in an area in which a radio wave is not
received or is weak, such as the inside of a building, the basement
of a building, a subway, a tunnel or an apartment complex of a
residential area. The distributed antenna system is used to extend
the coverage of a base station such that a service is provided to a
shadow area which a signal of a base station is unlikely to
reach.
[0005] For example, in the case of the downlink among the services
provided by the distributed antenna system, the headend device
serves to combine signals received from the base station and then
convert the signals into an optical signal thereby transmitting it
to the remote device, and the remote device restores the received
optical signal to the original signal and amplifies the restored
signal thereby transmitting it to a terminal.
[0006] At this time, the higher the signal-to-noise ratio (SNR) of
an optical signal transmitted to the remote device from the headend
device, the more the quality of the service is improved. However,
since there is a limit in increasing the power of a signal to
improve the signal-to-noise ratio to increase the power of the
signal, the power level of the signal, that is, the transmission
resource is limited. For that reason, in the case where various
base station signals are combined to be transmitted as an optical
signal, there is a problem that the distributed antenna system for
providing a multi-band service should distribute appropriately the
transmission resource for each of the base station signals so that
the base station signals each are transmitted with an optimized
power.
[0007] In a conventional distributed antenna system, a technician
directly analyzes, by using a measuring instrument in the field,
signals inputted to the distributed antenna system, and then
distributes the limited transmission resource in a manner of
controlling attenuation for each signal. However, according to the
conventional art, since the technician in the field often performs
the repeated optimization of the transmission resource distribution
of the distributed antenna system according to his ability, there
is a problem that a lot of manpower and time is required.
[0008] An object of a headend device of a distributed antenna
system and a signal processing method thereof according to the
technical features of the inventive concept is to efficiently
optimize and thereby distribute a transmission resource of a
distributed antenna system for each of signals, and aim at the
convenience of an administrator.
SUMMARY
[0009] According to an aspect of the inventive concept, a headend
device includes a spectrum analysis unit configured to analyze a
frequency spectrum of a plurality of base station signals and
detect characteristic information of the plurality of the base
station signals, a control unit configured to generate a control
signal to control the power of the plurality of base station
signals on the basis of the characteristic information detected,
and a plurality of RF units configured to receive at least one of
the plurality of the base station signals, adjust the power of the
base station signals received according to the control signal and
output the power-adjusted base station signals.
[0010] According to an embodiment of the inventive concept, the
characteristic information may include the bandwidth information of
the plurality of the base station signals, and the control unit may
be configured to generate the control signal on the basis of the
bandwidth information of the plurality of the base station
signals.
[0011] According to another embodiment of the inventive concept,
the control unit may be configured to calculate the proportional
relationship between the bandwidths of the plurality of the base
station signals, and generate the control signal so that the power
of the plurality of the base station signals corresponds to the
proportional relationship between the bandwidths calculated.
[0012] According to still another embodiment, the control signal
may be a signal for controlling the power of different base station
signals to correspond to a power level of the base station signal
with the lowest bandwidth among the plurality of the base station
signals.
[0013] According to yet another embodiment of the inventive
concept, the characteristic information may include input power
information and channel number information of the plurality of the
base station signals, and the control unit may be configured to
generate the control signal for controlling the power of the
plurality of the base station signals on the basis of the input
power information and the channel number information of the
plurality of base station signals.
[0014] According to still yet another embodiment of the inventive
concept, the control unit may be configured to calculate a
normalized factor using the sum of the input power of each of the
plurality of base station signals and the sum of the number of the
channels of each of the plurality of the base station signals,
calculate a power adjustment value for each of the plurality of the
base station signals by using the normalized factor, and generate
the control signal for controlling the power of the plurality of
the base station signals to correspond to the power adjustment
value.
[0015] According to a further embodiment of the inventive concept,
the plurality of RF units may include an attenuator for adjusting
the power of the received base station signals according to the
control signal.
[0016] According to another further embodiment of the inventive
concept, the headend device may further include a
combining/distribution unit configured to receive and combine the
power-controlled base station signals outputted from the plurality
of the RF units, and at least one optical unit configured to
receive the combined base station signals outputted from the
combining/distribution unit and convert the combined base station
signals into an optical signal to thereby output the optical
signal.
[0017] According to another aspect of the inventive concept, a
signal processing method of a headend device in a distributed
antenna system including the headend device and at least one remote
device which is operatively coupled to the headend device, the
method comprising the steps of: analyzing a frequency spectrum of a
plurality of base station signals to detect characteristic
information on the plurality of the base station signals; adjusting
a power of the plurality of the base station signals based on the
characteristic information detected; combining the power-adjusted
base station signals; and converting the combined base station
signals into an optical signal to thereby output the optical
signal.
[0018] According to an embodiment of the inventive concept, the
step of detecting the characteristic information of the plurality
of the base station signals may include detecting at least one of
bandwidth, channel number and input power of the plurality of the
base station signals as the characteristic information.
[0019] According to another embodiment of the inventive concept,
the step of adjusting the power of the base station signals may
include calculating the proportional relationship between the
bandwidths of the plurality of the base station signals and
adjusting the power of the plurality of base station signals so
that the power of the plurality of the base station signals
corresponds to the proportional relationship between the calculated
bandwidths.
[0020] According to still another embodiment of the inventive
concept, the step of controlling the power of the plurality of the
base station signals may adjust the power of the different base
station signals to correspond to a power level of the base station
signal with a minimum bandwidth among the plurality of the base
station signals.
[0021] According to yet another embodiment of the inventive
concept, the step of controlling the power of the plurality of the
base station signals may include calculating a normalized factor by
using the sum of the input power of each of the plurality of the
base station signals and the sum of the number of channels of each
of the plurality of the base station signals; calculating a power
adjustment value for each of the plurality of the base station
signals using the normalized factor; and adjusting the power of the
plurality of the base station signals to correspond to the power
adjustment value.
[0022] According to the headend device of the distributed antenna
system and the signal processing method thereof according to the
inventive concept, it can evenly distribute the limited
transmission resources effectively for each of the base station
signals by controlling the power of the base station signals
according to the characteristic of the base station signals without
the intervention of an administrator and it can aim at the
convenience of the administrator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Exemplary embodiments of the inventive concept will be more
clearly understood from the following detailed description taken in
conjunction with the accompanying drawings in which:
[0024] FIG. 1 is a schematic block diagram showing a distributed
antenna system according to an embodiment of the inventive
concept.
[0025] FIG. 2 is a schematic block diagram showing a portion of the
configuration of a headend device according to an embodiment of the
inventive concept.
[0026] FIG. 3 is a flow chart illustrating a signal processing
method of a headend device according to an embodiment of the
inventive concept.
[0027] FIG. 4 is a flow chart illustrating an embodiment of the
steps of controlling the power of the base station signals shown in
FIG. 3.
[0028] FIG. 5 is a flow chart illustrating another embodiment of
the steps of controlling the power of the base station signals
shown in FIG. 3.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The inventive concept may be made with various changes and
embodied in different forms, but, specific embodiments of the
inventive concept will be described below in detail with reference
to the accompanying drawing. However, this is not intended to limit
the inventive concept to certain embodiments, but it should be
understood as including all modifications, equivalents and
substitutes included in the spirit and scope of the invention.
[0030] In the following descriptions of the inventive concept, if
detailed descriptions of well-known technology that is determined
to unnecessarily obscure the subject matter of the inventive
concept, the detailed descriptions thereof will be omitted.
Further, the numbers (e.g., the first, second, etc.) used in the
course of being described in the specification are used just to
distinguish one component from the other components.
[0031] Further, in this specification, when referred to as one
component "is connected to" or "is accessed to" the other
component, it may be understood as meaning that the one component
is connected directly to the other components, but, as long as any
particular descriptions to the contrary are not made, it should be
understood that the one component may be connected or accessed to
the other component via another component in the middle
thereof.
[0032] Further, the terms of "-unit", "-tor", "-device", "-module",
etc. described in the present specification refer to a unit that
processes at least one function or operation, which may be
implemented with hardware or software or in a combination of
hardware and software
[0033] And, in the descriptions, it will be appreciated by one
skilled in the art that components in the configuration are
distinguished from one another just on the basis of the main
functions each component is in charge. That is, two or more
components in the configurations to be described below may be
integrated into one component, or one component in the
configuration may be divided into two or more components according
to each function separated in more detail. And, each of the
components to be described below may additionally perform any or
all of the functions other components are in charge in addition to
the main functions each one is in charge, and, any of the main
functions each of the components is in charge may be dedicated and
performed by other components.
[0034] The distributed antenna system according to one embodiment
of the inventive concept is a coverage system for an in-building
service that transfers voice communications and data communications
with high quality and seamless access. In addition, it is a system
for servicing analog and digital phone systems, which provide a
service within a plurality of bands, in a single antenna.
[0035] The distributed antenna system according to an embodiment of
the inventive concept may be provided mainly in general public and
private facilities such as shopping malls, hotels, campuses,
airports, hospitals, subways, stadiums, convention centers,
etc.
[0036] The distributed antenna system according to an embodiment of
the inventive concept may improve poor radio-wave environment in a
building, improve poor received signal strength indication (RSSI)
and overall received sensitivity Ec/Io (chip energy/others
interference) of a mobile terminal, and service the mobile
communications even in a corner of the building thereby enabling a
communication service user to freely make a call at any place in
the building.
[0037] The distributed antenna system according to one embodiment
of the inventive concept can support a mobile communication
standard used all over the world. For example, the distributed
antenna system may support a very high frequency (VHF), an ultra
high frequency (UHF), frequencies such as 700 MHz, 800 MHz, 850
MHz, 900 MHz, 1900 MHz, 2100 MHz band, 2600 MHz band, etc. and a
service of TDD mode as well as a service of FDD mode. Further, the
distributed antenna system may support a large number of mobile
communication standards, for example, an Advanced Mobile Phone
Service (AMPS) as a typical mobile communication service of an
analog and a time division multiple access (Time-Division
Multiplexing Access, TDMA) as a digital, a code division multiple
access (CDMA), an asynchronous CDMA (Wideband Code Division
Multiple Access, WCDMA), a high speed downlink packet access
(HSDPA), a long-term evolution (LTE), a long-term evolution
advanced (LTE-A), etc.
[0038] Hereinafter, preferred embodiments of the inventive concept
will be described in detail.
[0039] FIG. 1 is a schematic block diagram showing a distributed
antenna system according to an embodiment of the inventive
concept.
[0040] Referring to FIG. 1, the distributed antenna system 10 may
include a headend device 110 and first to mth remote devices 130_1
to 130_m (wherein m is natural number greater than 1).
[0041] The headend device 110 may be coupled to the first to nth
base stations BTS_1 to BTS_n (wherein n is natural number greater
than 1) through a predetermined transmission medium, for example,
such as a coaxial cable and the like. In another embodiment, the
headend device 110 may be coupled to the first to nth base stations
BTS_1 to BTS_n by wireless.
[0042] The headend device 110 may receive the base station signals
from the first to nth base stations BTS_1 to BTS_n. Here, the first
to nth base stations BTS_1 to BTS_n may provide the base station
signal of RF type to headend device 110, but the technical feature
of the inventive concept is not limited thereto. In yet another
embodiment, at least a portion of the first to nth base stations
BTS_1 to BTS_n may provide the base station signal of a digital
type to the headend device 110, in this case, the headend device
110 may be provided with an interface unit for converting the base
station signal of a digital type into the base station signal of RF
type. The base station signals each may have a specific frequency
band according to the services provided by the corresponding base
station among the first to nth base stations BTS_1 to BTS_n.
[0043] The headend device 110 may have a spectrum analysis unit
117. The spectrum analysis unit 117 may analyze the frequency
spectrum of the base station signals to detect the characteristic
information for each of the base station signals. The
characteristic information may include, for example, the bandwidth
information, the channel number information, and the input power of
the base station signals.
[0044] The headend device 110 may adjust the power of each of the
base station signals based on the characteristic information
detected by the spectrum analysis unit 117. The headend device 110
may combine the power-controlled base station signals and convert
the combined base station signals into an optical signal. A
detailed configuration and a method for a signal processing such as
a power control of the base station signals of the headend device
110 will be described in further detail below with reference to
FIGS. 2 to 5.
[0045] The headend device 110 may be coupled to the first to mth
remote devices 130_1 to 130_m through a transmission medium, for
example, the optical cable. The headend device 110 may transmit the
optical signal to each of the first to mth remote devices 130_1 to
130_m through a corresponding transmission medium. In another
embodiment, the headend device 110 may be coupled to an expansion
device (not shown) through a transmission medium, for example, an
optical cable and may transmit the optical signal to the expansion
unit through the transmission medium. The expansion device may
transmit the optical signal received from the headend device 110 to
a portion of the remote devices coupled through the expansion
device and the transmission medium, for example, the optical
cable.
[0046] The first to mth remote devices 130_1 to 130_m may restore
the received optical signal into the original base station signals
and amplify the restored base station signals thereby emitting it
through an antenna (not shown). The first to mth remote devices
130_1 to 130_m may be connected with an optical unit (see "115" of
FIG. 2) of the headend device 110 for each group, and receive the
optical signal from the optical unit corresponding to each group.
For example, the first to ith remote devices 130_1 to 130_i,
(wherein i is natural number greater than 1 and less than m) and
the (i+1)th to mth remote devices 130_i+1 to 130_m may be connected
to each of the different optical units, and receive the optical
signal from the corresponding optical units, respectively.
[0047] As such, in the distributed antenna system 110, the headend
device 110 directly controls the power of the base station signals
based on the characteristic of each of the plurality of the base
station signals, combines the power-controlled base station signals
and then converts the combined signals into an optical signal
thereby transmitting it to the first to mth remote devices 130_1 to
130_m.
[0048] Thus, the distributed antenna system 110 may allow the
limited transmission resource of the headend device 110 to be
evenly distributed even without intervention of an administrator
according to the characteristic of each of the plurality of the
base station signals, the efficient distribution of the
transmission resource and the convenience of the manager can be
achieved.
[0049] FIG. 2 is a schematic block diagram showing a partial
configuration of the headend device an embodiment of the inventive
concept. In the description of FIG. 2, it will be described with
reference to FIG. 1, but descriptions overlapped the descriptions
of FIG. 1 will be omitted for convenience.
[0050] Referring to FIGS. 1 and 2, the headend device 110 may
include the first to nth RF units 111_1 to 111_n, the
combining/distribution unit 113, the first to j-th optical units
115_1 to 115_j, the spectrum analysis unit 117 and the control unit
119.
[0051] The first to nth RF units 111_1 to 111_n each may receive
the base station signal from the corresponding base station among
the first to nth base stations BTS_1 to BTS_n. However, this is not
limited to this embodiment, and in another embodiment, at least two
or more RF units of the first to nth RF units 111_1 to 111_n may
receive the base station signal from any one of the first to nth
base stations BTS_1 to BTS_n.
[0052] The first to nth RF units 111_1 to 111_n may be provided
with an attenuator (ATT) to adjust the power of the base station
signal. The attenuator (ATT) may adjust the power of the base
station signal in response to a control signal supplied from the
control unit 119.
[0053] The combining/distribution unit 113 may combine the
power-adjusted base station signals outputted from the first to nth
RF units 111_1 to 111_n. The combining/distribution unit 113 can
distribute the combined base station signals to the first to j-th
optical units 115_1 to 115_j.
[0054] The first to j-th optical units 115_1 to 115_j may convert
the combined base station signals output from the
combining/distribution unit 113 into an optical signal to thereby
output the optical signal. That is, the first to j-th optical units
115_1 to 115_j may transmit the optical signal through a
corresponding transmission medium to the remote device.
[0055] The spectrum analysis unit 117 may receive the base station
signal from the plurality of the base stations and analyze the
frequency spectrum of the received base station signals to detect
the characteristic information.
[0056] In some embodiments, the spectrum analysis unit 117 is
coupled to an input terminal of each of the first to nth RF units
111_1 to 111_n connected to the corresponding base station of the
first to nth base stations (BTS_1 to BTS_n) thereby receiving the
base station signals inputted to the first to nth RF units 111_1 to
111_n and analyzing the frequency spectrum of the received base
station signals to detect the characteristic information.
[0057] However, the inventive concept is not limited to this
embodiment. In another embodiment, the spectrum analysis unit 117
is coupled to an output terminal of each of the first to nth RF
units 111_1 to 111_n connected to the combining/distribution unit
113 thereby receiving the base station signals outputted from the
first to nth RF units 111_1 to 111_n and analyzing the frequency
spectrum of the received base station signals. In this case, the
spectrum analysis unit 117 may analyze the frequency spectrum of
the base station signals outputted from the first to nth RF units
111_1 to 111_n, on the basis of the information on the base station
signal processing of the RF unit, which is provided from the
control unit 119, for example, the information on the power control
result and the like, thereby detecting the characteristic
information.
[0058] In yet another embodiment, the spectrum analysis unit 117
may receive the base station signals directly from the first to nth
base stations BTS_1 to BTS_n without being coupled to the first to
nth RF units 111_1 to 111_n, or through an additional interface
means, and analyze the frequency spectrum of the received base
station signals to detect the characteristic information.
[0059] The control unit 119 may generate a control signal for
controlling the power of the base station signals based on the
characteristic information of the base station signals detected by
the spectrum analysis unit 117.
[0060] In some embodiments, the control unit 119 may generate a
control signal for controlling the power of the base station
signals based on the bandwidth information of the base station
signals out of the detected characteristic information.
Specifically, the control unit 119 may calculate a proportional
relationship between the bandwidths of the detected base station
signals, and generate the control signal so that the power of the
base station signals corresponds to the proportional relationship
between the calculated bandwidths. Herein, the control signal may
be a signal for controlling the power level of another signal to
correspond to the power level of the base station signal with the
lowest bandwidth.
[0061] The case where the plurality of base station signals
includes GSM signal, CDMA signal, WCDMA signal and LTE 10M signal
will be further described as an example. The GSM signal has a
bandwidth of approximately 200 kHz, the CDMA signal approximately
1.23 MHz, the WCDMA signal approximately 3.84 MHz, the LTE 10M
signal approximately 9 MHz, respectively. The control unit 119
calculates a proportional relationship between the bandwidths of
the base station signals as 1:6:20:45 (GSM signal:CDMA signal:WCDMA
signal:LTE 10M signal), and generates a control signal for
controlling the power levels of different base station signals as a
power level of the GSM signal having the lowest value, i.e., the
minimum bandwidth, of the proportional relationship so that the
power of the base station signals correspond to the proportional
relationship between the calculated bandwidths.
[0062] The above-described embodiment is applied not only to the
case the base station signals having a single channel, but also to
the case the base station signals having a predetermined number of
channels. For example, in the case of the base station signals
having a predetermined number of channels, the above-described
embodiment may be applied on the basis of a unit bandwidth of each
of the base station signals (that is, a bandwidth of a single
channel).
[0063] In another embodiment, the control unit 119 may generate a
control signal for controlling the power of the base station
signals on the basis of the input power information and channel
number information of the base station signals out of the detected
characteristic information. In detail, the control unit 119 may
calculate the normalized factor by using the sum of the input power
of each of the base station signals and the sum of the channel
number of each of the base station signals, calculate the power
adjustment value for each of the plurality of the base station
signals using the normalized factor calculated, and generate the
control signal for controlling the power of the base station
signals so as to correspond to the calculated power adjustment
value. Here, the normalized factor may mean a value obtained by
dividing the sum of the input power of each of the base station
signals by the sum of the channel number of each of the base
station signals, and the power adjustment value may mean a value
obtained by multiplying the input power of each of the base station
signals by the normalized factor.
[0064] On the other hand, when the control unit 119 generates the
control signal for controlling the power of the base station
signals, it may use the characteristic information already stored
or the characteristic information inputted in real time by an
administrator, for a portion of the base station signals. For
example, when the bandwidths of a portion of the base station
signals are mutually similar or at least a portion of the
bandwidths is overlapped, the control signal may be generated by
using the characteristic information associated with the bandwidths
of the corresponding base station signals stored in advance or
inputted in real time by an administrator.
[0065] The control unit 119 may transmit the generated control
signal to the first to nth RF units 111_1 to 111_n, and thus the
attenuator (ATT) of the first to nth RF units 111_1 to 111_n may
adjust and output the power of the base station signals.
[0066] In this way, the headend device 110 controls the power of
the base station signals according to the characteristic of the
base station signals without the intervention of an administrator,
then combines the base station signals into one signal, and
photo-converts the combined signals thereby transmitting it to the
remote device. Accordingly, the headend device 110 can evenly and
effectively distribute the transmission resources limited due to
the limit of the signal-to-noise ratio (SNR) of the optical signals
to each of the base station signals, thereby aiming at the
convenience of an administrator.
[0067] FIG. 3 is a flowchart illustrating a signal processing
method of the headend device according to an embodiment of the
technical features of the inventive concept, FIG. 4 is a flowchart
illustrating an embodiment of a step of controlling the power of
the base station signals shown in FIG. 3, and FIG. 5 is a flowchart
illustrating another embodiment of controlling the power of the
base station signals shown in FIG. 3. The methods shown in FIGS. 3
to 5 are composed of the steps of being processed in time series in
the headend device 110 shown in FIGS. 1 and 2. Accordingly, even
though it is omitted below, the descriptions described in the
foregoing with respect to the headend device 110 shown in FIGS. 1
and 2 may be applied even to the methods illustrated in FIGS. 3 to
5.
[0068] Referring first to FIG. 3, in step S3100, the spectrum
analysis unit 117 may detect the characteristic information of the
plurality of the base station signals by analyzing the frequency
spectrum of the plurality of the base station signals. The spectrum
analysis unit 117 may detect, as the characteristic information, at
least one of the bandwidth, the channel number and the input power
of the plurality of base station signals.
[0069] In step S3300, the control unit 119 and the first to nth RF
units 111_1 to 111_n may control the power of the plurality of base
station signals on the basis of the characteristic information
detected by the spectrum analysis unit (117). In detail, the
control unit 119 may generate the control signal for controlling
the power of the plurality of the base station signals on the basis
of the characteristic information detected, and the first to nth RF
units 111_1 to 111_n may control and output the power of the
corresponding base station signal out of the plurality of the base
station signals in response to the control signal.
[0070] Referring to FIG. 4 illustrating an embodiment of step
S3300, in step 4100, the control unit 119 may calculate the
proportional relationship between the bandwidths of the plurality
of the base station signals.
[0071] In step 4300, the control unit 119 and the first to nth RF
units 111_1 to 111_n may adjust the power of the plurality of the
base station signals so that the power of the plurality of the base
station signals corresponds to the proportional relationship
between the calculated bandwidths. Specifically, the control unit
119 may generate the control signal for controlling the power of
the plurality of the base station signals so that the power of the
plurality of the base station signals corresponds to the
proportional relationship between the calculated bandwidths, and
the first to nth RF units 111_1 to 111_n may adjust and output the
power of the corresponding base station signal out of the plurality
of the base station signals in response to the control signal.
Herein, the control signal may be a signal for controlling the
power of the different base station signals so as to correspond to
the power level of the base station signal having a minimum
bandwidth out of the plurality of the base station signals.
[0072] Referring to FIG. 5 showing another embodiment of step
S3300, in step S5100, the control unit 119 may calculate the
normalized factor by using the sum of the input power of each of
the plurality of the base station signals and the sum of the
channel number of each of the plurality of base station signals.
The normalized factor is a value obtained by dividing the sum of
the input power of each of the plurality of the base station
signals by the sum of the channel number of each of the plurality
of the base station signals.
[0073] In step S5300, the control unit 119 may calculate the power
adjustment value for each of the plurality of the base station
signals using the normalized factor. The power adjustment value
means a value obtained by multiplying the input power of each of
the plurality of the base station signals by the normalization
factor.
[0074] In step S5500, the control unit 119 and the first to nth RF
units 111_1 to 111_n may adjust the power of the plurality of the
base station signals so as to correspond to the power adjustment
value. Specifically, the control unit 119 may generate the control
signal for controlling the power of the plurality of base station
signals so as to correspond to the power adjustment value, and the
first to nth RF units 111_1 to 111_n may control and output the
power of the corresponding base station signal out of the plurality
of the base station signals in response to the control signal.
[0075] Referring again to FIG. 3, in S3500, the
combining/distribution unit 113 may combine the power-adjusted base
station signals outputted from the first to nth RF units 111_1 to
111_n.
[0076] In step S3700, the first to j-th optical units 115_1 to
115_j may receive the combined base station signals from the
combining/distribution unit 113, and convert the received base
station signals into an optical signal to output it.
[0077] While the inventive concept has been described with respect
to the preferred embodiments, it will be apparent to those skilled
in the art that various changes and modifications may be made
without departing from the spirit and scope of the invention as
defined in the following claims.
* * * * *