KR20140121551A - Distributed antenna system - Google Patents

Abstract

The present invention provides a distributed antenna system. The distributed antenna system comprises: a master unit which transceives a communications signal with a base station; a hub unit which receives the communications signal processed by the master unit or transmits the communications signal to the master unit; a remote unit which transmits the communications signal with the hub unit; and a photoelectric composite cable which connects the hub unit with the remote unit. The remote unit receives power from the hub unit through the photoelectric composite cable.

Description

[0001] The present invention relates to a distributed antenna system,

One embodiment of the present invention relates to a distributed antenna system (DAS).

Wireless communication refers to a communication method using radio waves and is also generally called radio frequency (RF) communication. Wireless communication using radio waves modulates information to be transmitted by radio waves to transmit radio waves through a power amplifier (PA), demodulates the radio waves received at the receiving side, and receives information.

In the case of bidirectional wireless communication such as a cellular phone, a transmission frequency and a receiving frequency are separately set and transmitted and received at the same time. In addition, the two-way wireless communication system allocates a communication channel such that a plurality of users use different communication channels.

In such a wireless communication system, problems such as limitation of the capacity of the subscriber and limitation of the service area should be considered. To do this, the actual wireless communication system divides the service area into a plurality of cells to perform communication.

On the other hand, the wireless communication system adjusts the cell coverage so as not to cause the shadow area, but in the actual environment, the shadow area due to the building or underground space occurs. In this case, a relay system is installed in the shaded area, and a signal from the base station is relayed to the terminals.

Among these relay systems, the distributed antenna system has a plurality of distributed antennas arranged in a conventional cell coverage, and it is possible to prevent the propagation of radio waves due to a mountain, a building or other feature, The signal is amplified so that the signal of the base station can be reached to serve the shadow area, and the signal of the terminal in the shadow area is connected to the base station so that the signal can reach the base station.

The distributed antenna system may include a master hub unit (MU), a hub unit (HU), and a remote unit (RU) to relay communication signals between a base station and a user terminal. In the conventional distributed antenna system in the 2G / 3G environment, there is no change in the service frequency, but in the current 4G wireless communication environment, the service frequency of the higher-order base station system frequently changes. In this case, it is necessary to manually change the operation mode of the MU connected to the host base station system. Therefore, the operator has to set the operation mode according to the antenna output frequency pattern of the base station visited by the operator in advance, May be unnecessarily delayed.

In addition, conventionally, while the hub unit and the remote unit are connected by optical cables, the remote unit has a separate power supply unit. In this case, there is a problem that a separate UPS for the remote unit must be installed in order to maintain the service in the event of a power failure because additional electrical installation work is required to install the remote unit.

To solve this problem, the hub unit and the remote unit are connected by a UTP cable. A UTP cable is provided with a power supply line, so that power can be supplied from the hub unit to the remote unit, and a separate power supply unit is not required for the remote unit. However, in the case of UTP cable, since the signal is transmitted using the conductor line, there is a limitation on the distance that the signal can be transmitted without loss, and there is a limitation also on the power that can be transmitted by the UTP cable. .

SUMMARY OF THE INVENTION The main object of the present invention is to provide a distributed antenna system capable of automatically detecting an output frequency pattern of a base station system and automatically setting an operation mode.

Another object of the present invention is to provide a distributed antenna system in which system installation and maintenance are facilitated and transmission distances of communication signals are increased.

A communication relay apparatus according to an embodiment of the present invention includes a master unit capable of transmitting / receiving a communication signal with a base station, a hub unit receiving the communication signal processed by the master unit or transmitting a communication signal to the master unit, A remote unit capable of transmitting / receiving a communication signal with the hub unit, and a photoelectric hybrid cable connecting the hub unit and the remote unit to each other, wherein the remote unit is powered from the hub unit through the photoelectric hybrid cable Can be supplied.

In the present invention, the remote unit can operate with the power supplied from the hub unit without a separate power source.

In the present invention, the hub unit may include a power supply unit capable of supplying power to the remote unit.

In the present invention, the remote unit may receive an optical signal from the hub unit through the photoelectric hybrid cable, and convert the optical signal into an electrical signal.

In the present invention, the communication signal can be transmitted and received between the hub unit and the remote unit via the photoelectric hybrid cable.

In the present invention, the photoelectric composite cable may include an optical cable disposed at the center of the photoelectric composite cable, at least one first power line unit surrounding and enclosing the optical cable, at least one second power line unit, Wherein the optical cable comprises a cushioning tube disposed at the center of the optical cable, a plastic tube gathered in the longitudinal direction around the cushioning tube, and an outer layer surrounding the power line unit and the second power line unit, And a sheath layer surrounding the optical fiber unit, wherein one of the first power line unit, one second power line unit, and one optical fiber unit And can be branched and connected to one of the remote units.

In the present invention, the cushioning tube may have a diameter allowing the optical fiber unit to be stably supported by each of the at least one optical fiber unit.

In the present invention, the plastic tube may be made of polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA), or a combination thereof.

In the present invention, the buffer tube may be made of a foamed plastic resin having a lower strength than the plastic tube.

In the present invention, a waterproof material including a jelly compound, a waterproof powder, a waterproofing yarn, or a combination thereof may be mounted in the plastic tube together with the optical fiber core wire.

In the present invention, the power source may be supplied to the remote unit through the power line.

In the present invention, the communication signal can be transmitted and received between the hub unit and the remote unit via the optical cable.

In the present invention, the photoelectric composite cable includes a first power line unit, a second power line unit, and a ground line, an outer layer surrounding and surrounding the first power line unit, the second power line unit, And an optical fiber unit in contact with the outer shell layer.

The master unit includes an A / D converter for digitally converting an incoming signal from the base station to generate a signal sample, a signal detector for determining whether or not to receive a communication signal based on the signal sample, And a mode controller for setting an operation mode based on the determination result of the reception.

The present invention may further include a communication mode determination unit that determines a communication mode of the incoming signal.

In the present invention, the mode control unit may set the operation mode based on whether or not the communication signal is received and a result of the determination of the communication method.

In the present invention, the communication mode determination unit may determine a communication mode of the incoming signal for each service frequency band.

In the present invention, the signal detector may determine whether the communication signal is received for each service frequency band.

In the present invention, the mode control unit may operate only when the communication signal is received from the signal detection unit.

In the present invention, the base station may further include a signal input / output unit connected to the base station by wire to transmit and receive the communication signal.

In the present invention, it may further comprise a photoelectric conversion unit for photoelectrically converting the communication signal, and a light transmission unit for transmitting the photoelectric-converted optical signal in the set operation mode.

In the present invention, the signal detector may receive the communication signal when the size of the signal sample is equal to or greater than a preset reference value.

According to the embodiment of the present invention, the output frequency pattern of the host base station system can be automatically detected to set the operation mode automatically.

In addition, there is no need for a separate power supply unit in the remote unit, thereby reducing system installation cost, facilitating installation, facilitating maintenance of the system, and supplying a high power source, thereby enabling a flexible network design.

1 is a block diagram schematically showing a distributed antenna system according to an embodiment of the present invention.
2 is a block diagram schematically showing a master unit of a distributed antenna system according to an embodiment of the present invention.
3 is a table showing an example of the operation mode of the master unit shown in Fig.
FIG. 4 is a view for explaining an operation mode of the master unit shown in FIG. 2. FIG.
5 is a block diagram schematically showing a hub unit of a distributed antenna system according to an embodiment of the present invention.
6 is a configuration diagram schematically showing a remote unit of a distributed antenna system according to an embodiment of the present invention.
7 is a cross-sectional view schematically showing a photoelectric composite cable of a distributed antenna system according to an embodiment of the present invention.
8 is a cross-sectional view schematically showing the optical cable shown in Fig.
9 is a cross-sectional view schematically showing a photoelectric composite cable according to another modification.
10 is a cross-sectional view schematically showing a photoelectric composite cable according to still another modification.
11 is a flowchart schematically showing a communication signal relaying method of a distributed antenna system according to an embodiment of the present invention.

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities. It should be understood, however, that the invention is not intended to be limited to the particular 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.

In this specification, a user terminal is a device that transmits and receives voice or data to and from other user terminals via a base station or a repeater, and may be a mobile phone, a smart phone, a laptop computer, , A PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), a navigation device, and the like.

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

1 is a block diagram schematically showing a distributed antenna system according to an embodiment of the present invention.

1, a distributed antenna system according to an exemplary embodiment of the present invention amplifies a downlink signal input from a base station (BS) 100 and transmits the amplified downlink signal to a user equipment (UE) . 1 shows an example of an in-building distributed antenna system for providing wireless communication coverage in a building. BS 100 is a base station (eNodeB, eNB), and MU 200 is a master unit HU 300 denotes a hub unit, and RU 400 denotes a remote unit.

A communication signal stream can be transmitted and received between the base station 100 and the master unit 200. [ At this time, the base station 100 and the master unit 200 are connected through a wired cable such as a coaxial cable, and the communication signal stream can be transmitted and received in the form of an RF signal or an electric signal.

The master unit 200 can digitally convert the communication signal transmitted from the base station 100 and transmit the converted communication signal to the hub unit 300 or the communication signal transmitted from the hub unit 300 to the base station 100 have. The master unit 200 and the hub unit 300 may be connected through an optical cable 600 and a plurality of hub units 300 may be connected to one master unit 200. The hub unit 300 may be directly connected to the master unit 200 or may be connected to the other hub unit 300 in parallel.

The hub unit 300 is connected to one or more remote units 400 and can transmit the optical signals received from the master unit 200 to the remote unit 400. [ At this time, the remote units 400-1 to 400-n are arranged for each layer as shown in FIG. 1, for example, so as not to cause a shadow area in the case of the in-building distributed antenna system. . The present invention is not limited to this, and a plurality of remote units may be arranged for each layer, and one remote unit may be arranged for a plurality of layers.

The hub unit 300 and the remote unit 400 may be connected by a photoelectric hybrid cable 700. The optical signal is transmitted and received between the hub unit 300 and the remote unit 400 through the photoelectric hybrid cable 700 and power can be supplied from the hub unit 300 to the remote unit 400. [ This will be described later.

The communication signal transmitted to the master unit 200 is transmitted to the remote unit 400 via the hub unit 300 and the remote unit 400 transmits the communication signal transmitted through the at least one antenna 500-1 to 500- Signal to the user terminal.

Meanwhile, the wireless communication system may provide a service mode such as CDMA, WCDMA, or LTE, and the base station 100 may transmit a communication signal in a predetermined service mode. The master unit 200 may detect the type of the communication signal received from the base station 100 and change the operation mode setting corresponding thereto.

Hereinafter, the detailed configuration of the master unit 200 and the automatic setting function of the operation mode will be described.

2 is a block diagram schematically showing a master unit of a distributed antenna system according to an embodiment of the present invention.

2, the master unit 200 includes a signal input / output unit 210, an A / D converter 220, an FPGA unit, a communication mode determination unit 240, a photoelectric conversion unit 260, And a D / A converter 280. The D / In addition, the FPGA unit may include a signal detection unit 230 and a mode control unit 250 therein.

The signal input / output unit 210 provides an interface to be connected to the base station 100 and can be connected to the base station 100 by wire to transmit and receive communication signals. The communication signal transmitted / received through the signal input / output unit 210 may be an analog signal of the RF signal. The downlink signal received from the base station 100 is converted into a digital signal by the A / D converter 220, while the uplink signal received from the user terminal is converted into an analog signal by the D / A converter 280, And may be transmitted to the base station 100 through the input / output unit 210.

The A / D converter 220 converts the input signal received through the signal input / output unit 210 into a digital signal, and samples the signal at predetermined intervals to generate a signal sample. The generated signal samples may be data in which the magnitude values of the incoming signals at specific times, for example, 00011, 00100, etc., are sequentially generated at predetermined time intervals.

The generated signal samples can be used as basic data for determining presence / absence of a communication signal by the signal detection unit 230. [ Specifically, the signal detector 230 may compare the generated signal samples with a threshold value to determine whether the incoming signal is a meaningful communication signal. For this, the signal detector 230 may store one or more threshold values set at predetermined time intervals in a separate table for management. If the data of the signal sample compared with the threshold value for a predetermined time exceeds the threshold value, the signal detector 230 may determine that the communication signal is inputted.

Meanwhile, the signal detector 230 may determine whether or not the communication signal is received for each service frequency band. The wireless communication system provides a wireless communication service using a predetermined frequency band. The wireless communication system subdivides the allocated frequency band into one or more service frequency bands and assigns the respective service frequency bands to different communication services for use have.

In Fig. 3 and Fig. 4, an example of such a service frequency band and corresponding operation mode is shown. 3, a service frequency band usable in the wireless communication system is divided into four sub-frequency bands F0 to F3, and each sub-frequency band can be divided into a plurality of operation modes by a combination of services used . For example, in the case of the operation mode 5, the sub frequency band F0 is not used, F1 is the MAIN port and the MIMO port both operate in LTE, and F2 and F3 operate in the WCDMA only in the MAIN port.

Fig. 4 (a) shows a reception frequency pattern of the service frequency band in the operation mode 5. When the usable frequency band in the wireless communication system is 1749.9 MHz to 1784.9 MHz, the sub frequency band F0 is not used, the signal received in the F1 frequency band is the LTE signal, and the WCDMA signal is transmitted through the F2 and F3 frequency bands Lt; / RTI >

In this case, the master unit 200 grasps the presence or absence of an incoming signal and each communication method for each sub-frequency band, and sets the operation mode to mode 5 accordingly. Specifically, the signal detector 230 compares the magnitude of the signal sample of the input signal generated by the A / D converter 220 with a predetermined threshold (for example, -50 dBm) of the table, It can be determined that the signal is a communication signal including meaningful data. The mode control unit 250 can reset the operation mode of the master unit 200 based on the determination result of the presence or absence of the communication signal in the signal detection unit 230. [

At this time, if it is determined that the communication signal is not received from the signal detecting unit 230, the mode controller 250 and the modules at the subsequent stage operate in an idle mode, and only when the communication signal is received, Mode (active mode).

The communication mode determination unit 240 may analyze the packet of the communication signal input through the downlink to distinguish whether the corresponding signal is a WCDMA signal or an LTE signal. The communication mode determination may be performed for each sub-frequency band, and the determination result may be transmitted to the mode control unit 250. [

The mode control unit 250 determines the communication method of each sub-frequency bandwidth based on the communication method obtained by the signal detection unit 230 and the communication method determination unit 240 and the result of the communication method of the received communication signal, The operation mode of the master unit 200 can be set. Thereafter, the communication signal received from the base station can be transmitted to the UE via the hub unit 300 and the remote unit 400 on the downlink path in the set operation mode. The remote unit 400 controls the output frequencies at the MAIN antenna port and the MIMO antenna port according to the operation mode. In the case of the mode 5, as shown in FIG. 4 (b), the MAIN antenna transmits the frequency bands F1, F2 and F3 And the MIMO antenna emits the F1 frequency band.

At this time, the communication signal sent to the hub unit 300 and the remote unit 400 may be converted into an optical signal by the photoelectric conversion unit 260 and transmitted through the optical transmission unit 270.

Meanwhile, the communication signal received through the uplink path from the UE is received by the master unit 200 through the optical transmission unit 270, converted into a digital signal through the photoelectric conversion unit 260, input to the FPGA unit, And may be converted to an analog signal in the D / A converter 280 for transmission to the base station.

With this configuration, the master unit 200 can determine the presence / absence of the communication signal and the communication method received from the base station 100 and automatically set the operation mode based on the communication signal, It is possible to solve problems such as device failure and communication failure due to setting errors and the like.

5 is a block diagram schematically showing a hub unit of a distributed antenna system according to an embodiment of the present invention.

Referring to FIG. 5, the hub unit 300 may include optical transmission units 310 and 340, photoelectric conversion units 320 and 330, a signal combining / distributing unit 360, and a power supply unit 350.

The optical signal transmitted from the master unit 200 may be received by the optical transmission unit 310 of the hub unit 300 and converted into an electrical signal via the photoelectric conversion unit 320. The electrical signal may be transmitted to the signal combining / distributing unit 360. The signal combining / distributing unit 360 may divide the signal transmitted from the photoelectric converting unit 320 into a plurality of signals. That is, the hub unit 300 is connected to a plurality of remote units 400, and the signal combining / distributing unit 360 is connected to the plurality of remote units 400 so as to transmit signals to the remote units 400 connected to the hub unit 300, The signal can be distributed.

Each of the electric signals distributed in the signal combining / distributing unit 360 is transmitted to the photoelectric converting unit 330 and converted into an optical signal. The optical signal is transmitted from the optical transmitting unit 340 to the photoelectric composite cable 700 To the remote unit 400 via the network. The photoelectric conversion unit 330 and the optical transmission unit 340 may be disposed in the hub unit 300 by the number of the remote units 400 connected to the hub unit 300. [

The optical signal transmitted from the remote unit 400 is transmitted to the optical transmission unit 340 of the hub unit 300 through the photoelectric hybrid cable 700 and is transmitted to the photoelectric conversion unit 330, the signal combining / distributing unit 360, And may be transmitted to the master unit 200 through the photoelectric conversion unit 320 and the light transmission unit 310. [

The hub unit 300 may further include a power supply unit 350. The power supply unit 350 can supply power to the remote unit 400. [ That is, the remote unit 400 itself is not provided with a separate power supply source and can be operated by the power supplied from the power supply unit 350 of the hub unit 300. The power of the power supply unit 350 can be transmitted by the photoelectric hybrid cable 700 connecting the hub unit 300 and the remote unit 400. [ The photoelectric hybrid cable 700 is composed of optical fibers and conductor wires and transmits optical signals between the hub unit 300 and the remote unit 400 through the optical fibers, Power can be supplied to the unit 400. A detailed description of the photoelectric hybrid cable 700 will be described later.

A plurality of remote units 400 are connected to the hub unit 300. All of the remote units 400 connected to the hub unit 300 can receive power from the hub unit 300. [ Since it is not necessary to provide a separate power supply device for each of the plurality of hub units 300, it is easy to install the remote unit 400, and the size of the remote unit 400 can be downsized, The remote unit 400 can be easily installed. In addition, since there is no power supply unit in the remote unit 400 itself, it is unnecessary to install a UPS for maintaining the power of the remote unit 400 and a separate power supply construction for installation of the remote unit 400 is unnecessary. Can be saved. In addition, the network design of the distributed antenna system can be made more flexible by using a smaller number of remote units 400 than when the photoelectric hybrid cable 700 capable of transmission of 1200 W or more is used.

6 is a configuration diagram schematically showing a remote unit of a distributed antenna system according to an embodiment of the present invention.

6, the remote unit 400 includes a light transmission unit 410, a photoelectric conversion unit 420, a digital signal processing unit 430, a D / A converter 440, an A / D converter 450, An input / output unit 460, and an antenna 470.

The optical signal transmitted through the photoelectric hybrid cable 700 is received by the optical transmission unit 410 of the remote unit 400 and the optical signal is converted into an electrical signal via the photoelectric conversion unit 420, Digital signal processing unit 430, and converted into an analog signal by the D / A converter 440. The analog signal may be amplified by the signal input / output unit 460 and transmitted to the user terminal through the antenna 470. [

The signal output from the user terminal is supplied to the antenna 470 of the remote unit 400, the signal input / output unit 460, the A / D converter 450, the digital signal processing unit 430, the photoelectric conversion unit 420, May be transmitted to the hub unit 300 through the photoelectric hybrid cable 410 and the photoelectric hybrid cable 700.

As described above, the remote unit 400 is connected to the hub unit 300 through the optical fibers in the photoelectric hybrid cable 700, and receives a signal from the hub unit 300 spaced apart from the remote unit 400 without signal loss . In case of a conventional UTP cable (Unshielded twisted pair cable), the distance to transmit a signal within a permissible signal loss range is limited to a maximum of 100 m, which limits the design of the system. However, according to the embodiment of the present invention, it is possible to transmit a signal through an optical fiber in the photoelectric hybrid cable 700, and to transmit a signal at a long distance without signal loss, thereby enabling a flexible distributed antenna system design.

Since the remote unit 400 receives power from the hub unit 300 through the photoelectric hybrid cable 700 without a separate power supply unit, it is possible to save installation cost in installing the remote unit 400, The remote unit 400 can be made relatively small, so that the remote unit 400 can be installed in a relatively small installation space. Power of 1200 W or more can be supplied through the photoelectric hybrid cable 700. Since the remote unit 400 can transmit a high-output RF signal, it is possible to design an optimum network with a relatively small number of remote units 400 .

7 is a cross-sectional view schematically showing a photoelectric hybrid cable 700 of a distributed antenna system according to an embodiment of the present invention.

7, the photoelectric hybrid cable 700 of the present invention includes an optical cable 20 disposed at the center of the photoelectric hybrid cable 700, at least one first power line Unit 30 and at least one second power source line unit 50 and an outer skin layer 70 surrounding and surrounding the first power source line unit 30 and the second power source line unit 50. [

The outer cover layer 70 is a part forming the outer shape of the photoelectric composite cable 700 and can protect the optical cable and the power line unit included in the photoelectric composite cable 700.

The outer cover layer 70 may be formed in a circular shape so that the first power line unit 30 and the second power line unit 50 are concurrently inscribed in the first power line unit 30 and the second power line unit 50, A metal layer 71 that surrounds the metal layer 71 and protects the power line units 30 and 50 and the optical cable 20 from an external impact and an outer coating layer 73 that surrounds the metal layer 71.

The metal layer 71 may be formed of a corrugated steel tape.

The outer coating layer 73 is preferably an environmentally friendly resin having flame retardant properties. For example, the outer coating layer 73 may be composed of polyethylene, polypropylene, polyvinyl chloride (PVC), or the like.

The outer layer 70 is formed on the inner surface of the metal layer 71 so that the first power line unit 30 and the second power line unit 50 are simultaneously inscribed in place of the metal layer 71, And a waterproof tape 75 surrounding the second power line unit 50 in a circular shape. The waterproof tape 75 may be disposed in a form of wrapping inner power line units with a waterproof material-treated nonwoven fabric. The waterproof coating layer 75 is formed in such a manner that the tape-like material is horizontally or extensively applied. By providing such a waterproof tape, it is possible to prevent the optical fiber and the cable from being damaged due to moisture penetration.

A rip cord (not shown) may be provided on the outer skin layer 70 (for example, on the metal layer 71 or the waterproof tape 75) so that the outer skin layer 70 can be easily peeled off .

The first power source line unit 30 and the second power source line unit 50 may include at least one unit power source line 31 and 51 constituted by a conductor and an insulative covering layer composed of an insulator surrounding the at least one unit power source line 31 and 51 (33; 53). It is preferable that the power line units are in conformity with a standard used for general power. The plurality of unit power supply lines 31 and 51 may be twisted together. The insulating coating layer (33; 53) is painted in various colors depending on the use purpose. It is preferable that the unit power supply lines 31 and 51 are made of copper and the insulating cover layer 33 and 53 are made of a resin material including polyethylene, polypropylene, or polyvinyl chloride.

The first power line unit 30 corresponds to the + terminal, and the second power line unit 50 corresponds to the - terminal. Can be branched in the photoelectric hybrid cable 700 so that one set of one first power line unit 30, one second power line unit 50, and one optical fiber unit (21 of FIG. 8) The one set may be connected to one remote unit 500 to transmit signals and power.

8 is a cross-sectional view schematically showing the optical cable shown in Fig.

8, the optical cable includes at least one optical fiber unit 21 in which a predetermined number of optical fiber core wires 21a are mounted in a plastic tube 21b made of a plastic resin, with a buffer tube 22 located at the center of the cable 20, And the sheath layer 24 surrounds the at least one optical fiber unit 21. The optical fiber unit 21 has a structure in which a plurality of optical fiber units 21 are arranged in the longitudinal direction.

The plastic tube 21b constituting the optical fiber unit 21 is formed of a plastic resin such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA) , And preferably made of polybutylene terephthalate (PBT). The polybutylene terephthalate (PBT) resin is excellent in flexibility and mechanical strength, has a high crystallization speed, and has a small shrinkage in the longitudinal direction after the tube 21b is manufactured.

The plastic tube 21b is generally cylindrical in shape and has a through hole through which the optical fiber core wire 21a, waterproofing material 21c, and the like can be mounted. The outer diameter / inner diameter of the plastic tube 21b is determined according to the use of the cable 20, and the standard is the number of the optical fiber core wires 21a mounted in the plastic tube 21b, The content of the waterproof material 21c, the bending property required in the cable 20, and the like.

That is, when the inner diameter of the plastic tube 21b is less than the standard, the content of the waterproof material 21c included in the tube 21b is insufficient and the number of the optical fiber core wires 21a is also decreased, On the other hand, when the outer diameter of the tube 21b is larger than the standard size, the diameter of the cable 20 is unnecessarily increased, which reduces the flexibility of the cable 20, thereby causing difficulties in winding.

The thickness of the plastic tube 21b may be determined in consideration of the mechanical strength and flexibility required for the tube 21b. For example, Or more, preferably 15% or more.

Preferably, the plastic tube 21b is formed on the outside of the color coating layer colored in different colors, so that the optical fiber unit 21 can be easily distinguished according to functions and actions of the optical fiber units 21, Can be easily distinguished.

A predetermined number of the optical fiber core wires 21a are mounted in the plastic tube 21b forming the optical fiber unit 21. [ The number of the optical fiber core wires 21a mounted in the plastic tube 21b may be one, two, or three or more as necessary. That is, the number of the optical fiber core wires 21a may vary depending on the data transmission efficiency of the optical cable including the optical fiber cable 21a, the flexibility of the cable, and the like.

Each of the optical fiber core wires 12 has a double cylindrical structure in which a portion called a core in the center is surrounded by a portion called a cladding around the core, A glass optical fiber made of a material having a relatively low refractive index is used as the cladding and glass or synthetic resin having a relatively low refractive index is used as the cladding so that light passing through the central portion is totally reflected, And so on. A multimode optical fiber having a diameter of several micrometers is defined as a single mode optical fiber and a multimode optical fiber having a diameter of several tens of micrometers is classified into a stepped or a hill type optical fiber depending on the refractive index distribution of the core.

The plastic tube 21b may be filled with a waterproof material 21c such as a jelly compound, a waterproof powder, a waterproofing yarn, or a combination thereof together with the optical fiber core wire 21a. When moisture penetrates into the optical cable 20, mechanical reliability may deteriorate or hydrogen gas may be generated due to chemical reaction with the metal in the cable 20. Moisture may move to the inside of the optical cable 20, It may also happen that the connecting equipment and the end equipment are corroded.

Therefore, the waterproofing material functions to prevent moisture from penetrating into the plastic tube 21b, and preferably ensures that the optical fiber core wire 21a flows in the plastic tube 21b.

The jelly compound as the waterproofing material 21c may be made of a resin having excellent thermal stability, water resistance, electrical insulation, etc. Preferably, the jelly compound is excellent in adhesion with the optical fiber core wire 21a, May be a superior thixotropic jelly compound.

As the waterproofing material 21c, the waterproof powder is a super absorbent polymer (SAP), and has a property of absorbing water up to tens to hundreds of times its own weight, so that moisture penetrates into the plastic tube 21b It is suitable for use as a waterproofing for preventing the waterproofing. The waterproof powder may be a polyacrylate salt, a PVA maleic acid reactant, an isobutylene maleic acid copolymer, a polyacrylonitrile polymer, a polyethylene oxide crosslinked product, a starch acrylonitrile polymer, a starch acrylic acid graft polymer, or the like.

The waterproof yarn as the waterproof material 21c can be inserted into the through hole of the plastic tube 21b, and the waterproof powder, which is the waterproof yarn attached to the continuous yarn or the waterproof powder, And a waterproof yarn made by twisting or bonding together with a yarn.

The waterproof yarn may have a thickness of, for example, 300 to 3,000 denier, a swelling capacity of 20 g / g or more, and a tensile strength of 3 to 150 N in distilled water. When the thickness of the waterproof yarn is less than 300 denier, it requires a lot of waterproof yarn in order to achieve a waterproof performance, which is not only difficult to work but also causes an increase in the price of the cable. If the waterproof yarn has a blowing capacity of less than 20 g / g, it may be difficult to achieve the desired waterproof performance. If the tensile strength is less than 3 N, It is possible to cause disconnection due to the tensile stress generated when the wire is bent.

As described above, in the optical cable 20 according to the present invention, at least one of the optical fiber units 21 (21a, 21b) in which a predetermined number of the optical fiber core wire 21a, the waterproof material 21c, Are gathered longitudinally about the cushioning tube 22 located at the center of the cable 20. The number of the optical fiber units 21 may be different depending on the use of the cable or the like and is preferably six in order to facilitate the optical cable 20 to keep its cross section circular.

On the other hand, due to the bending of the cable 20 which occurs when the optical cable 20 is wound on a reel, a drum or the like, the optical fiber core 21 of the optical fiber unit 21 included in the cable 20 21a may be subjected to stress, which may cause disconnection and deterioration of the optical fiber core wire 21a.

In order to solve such a problem, the strain of the cable 20 caused by the bending stress caused by the bending of the optical cable 20 is increased due to the expansion of the twisted optical fiber unit 21 Can be compensated for. That is to say, the length of the optical fiber unit 21 and the optical fiber core wire 21a included in the optical fiber unit 21 are adjusted to compensate for strain of the cable 20 caused by the reel of the optical cable 20, The optical fiber unit 21 can be gathered around the central buffer tube 22 with a helical twist or an SZ twist.

In this case, the optical fiber units 21 can maintain a twisted state at a predetermined pitch. The pitch of the optical fiber unit 21, which is twisted at such a pitch, is expanded by bending of the optical cable 20, The bending radius, etc. of the optical cable 20 so that the strain of the optical cable 20 can be compensated.

Meanwhile, the buffer tube 22 may be formed of a plastic tube 21b of the optical fiber unit 21, which absorbs shocks and is in contact with the optical cable 20 when an impact or a load is applied thereto, Not only protects the optical fiber core wire 21a, but also performs a function of imparting a tensile force to the cable 20. [

The cushioning tube 22 may be made of the same plastic resin as the plastic tube 21b, preferably a foamed plastic resin having a lower strength than the plastic tube 21b, for example, foamed polyethylene, Polyvinyl chloride (PVC) or the like. When the strength of the buffer tube 22 is lower than that of the plastic tube 21b, the shape of the buffer tube 22 is deformed when a load is applied in the lateral direction of the cable 20, It is easy to maintain the shape and to protect the optical fiber core wire 21a mounted therein.

There is no particular limitation on the shape of the buffer tube 22 as long as it can stably support at least one optical fiber unit 21 gathered around the buffer tube 22. Preferably, the buffer tube 22 has a circular cross-section, and the diameter of the circular tube is set such that the optical fiber unit 21 The diameter of each of the first and second electrodes 22a and 22b may be appropriately selected.

In the optical cable 20 according to the present invention, a tensile force tensile line (not shown) is provided in an empty space in the sheath layer 24, preferably outside the optical fiber unit 21, the buffer tube 22, 23). ≪ / RTI > The tensile strength tensile wire 23 functions to protect the optical fiber core wire 21a inside the optical cable 20 by supplementing the tensile strength of the optical cable 20 and is made of Kevlar aramid yarn, A fiber glass epoxy rod, a fiber reinforced polyethylene (FRP), a high strength fiber, a galvanized steel wire, a steel wire, or the like.

The optical cable 20 according to the present invention may have a structure in which the sheath layer 24 surrounds the periphery of the at least one optical fiber unit 21 gathered around the buffer tube 22. The thickness of the sheath layer 24 can be appropriately selected depending on the use of the optical cable 20, specifically, the overall diameter of the optical cable, the required flexibility, the bending property, and the like.

Meanwhile, the optical cable 20 according to the present invention may further include a reinforcing layer 25, a waterproof layer 26, or both, between the sheath layer 24 and the at least one optical fiber unit 21.

When the sheath layer 24 is formed directly on the outside of the optical fiber unit 21, the entire outer surface of the optical cable 20 may be unevenly formed or the material of the sheath layer 24 may be formed in the plastic tube of the optical fiber unit 21 21b. This may deteriorate the appearance of the cable 20, and may be undesirable because it is easy to receive unnecessary impact and frictional resistance during winding. Therefore, a metal reinforcing tape such as an aluminum foil is wrapped around the outside of the optical fiber unit 21 or wrapped around the outside of the optical fiber unit 21 with a reinforcing layer 25 formed of a transparent film, a nonwoven fabric, The sheath layer 24 can be formed in a state in which a near external shape is formed.

Further, the waterproof layer 26 may be formed on the exterior, interior, or both of the reinforcing layer 25. The waterproof layer 26 may be formed by horizontally inserting a waterproof tape such as a paper swellable tape into the optical fiber unit 21 or the reinforcing layer 25 and penetrating through the damaged portion of the sheath layer 24 When the waterproof layer 26 is disposed outside the reinforcing layer 25, it is possible to prevent the water from penetrating into the optical cable 20, Can be achieved.

In the optical cable 20 according to the present invention, a void space between the sheath layer 24 and the optical fiber unit 21 is a bedding body made of a waterproof material such as a jelly compound, a waterproof powder, Can be filled. The waterproof material such as the jelly compound, the waterproof powder, and the waterproof yarn may be the same as or different from the waterproof material 21c filled in the plastic tube 21b described above.

9 is a cross-sectional view schematically showing a photoelectric composite cable according to another modification.

9, the photoelectric hybrid cable 800 includes an optical cable 20 'disposed at the center of the photoelectric hybrid cable 800 and a plurality of first power line units 30 so as to circumscribe the optical cable 20' And a plurality of second power line units 50 are disposed on the first power line unit 30 and the outer layer 70 is in contact with the first power line unit 30 and the second power line unit 50, (700), but there is a difference in the configuration of the optical cable 20 '. That is, the optical cable 20 'may be arranged such that the cushioning tube 22 is disposed at the center of the optical cable 20' and is circumscribed by the cushioning tube 22. 7 is different in that the plastic tube 21b 'constituting the optical fiber unit 21' is a tight buffer and the plastic tube 21b is a loose tube.

10 is a cross-sectional view schematically showing a photoelectric composite cable according to still another modification.

10, the photoelectric hybrid cable 900 includes a first power line unit 30, a second power line unit 50, and a ground line 40 that are in contact with each other and an outer layer 70 surrounding and surrounding the first power line unit 30, And an optical fiber unit 21 "which circumscribes the power line 30, 50 or the ground line 40 and is in contact with the outer layer 70. The optical fiber unit 21" 21 or the optical fiber unit 21 'of Fig.

Such a photoelectric hybrid cable 900 transmits and receives optical signals between the hub unit 300 and the remote unit 400 by directly connecting the hub unit 300 and the respective remote units 400 without being branched separately The power can be supplied from the hub unit 300 to the remote unit 400. [

The photoelectric composite cable used in the distributed antenna system according to an embodiment of the present invention is not limited to the one shown in Figs. 7 to 10, and any form can be used as long as it is a combination of a power line and an optical cable.

11 is a flowchart schematically showing a communication signal relaying method of a distributed antenna system according to an embodiment of the present invention.

First, the master unit 200 receives an incoming signal from the base station via the signal input / output unit 210, digitizes it by the A / D converter 220, and extracts a signal sample (S100). The extracted signal samples are transmitted to the FPGA unit, and the signal detector 230 of the FPGA unit compares the signal samples with preset thresholds for each service frequency band (S102). If the signal samples are larger than the threshold value, (S104). If the size of the signal sample is less than the threshold value, it is determined that a communication signal using the service frequency band is not received from the base station (S108). If the communication signal is received, the communication mode determination unit 240 determines the service mode of the communication signal and provides the result to the mode control unit 250.

Thereafter, the mode control unit 250 determines the presence or absence of a communication signal for each service frequency band using the communication signal detection result of the signal detection unit 230, and sets the operation mode of the master unit 200 accordingly (S110). At this time, the operation mode can be set by reflecting the communication mode determination result of the communication mode determination unit 240. Thereafter, the received communication signal is converted into an optical signal by the photoelectric conversion unit 260, and the optical signal may be transmitted through the optical transmission unit 270 in the set operation mode (S112).

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

100: Base station 200: Master unit
300: Hub unit 400: Remote unit

Claims (22)

A master unit capable of transmitting and receiving communication signals with the base station;
A hub unit for receiving the communication signal processed by the master unit or transmitting a communication signal to the master unit;
A remote unit capable of transmitting and receiving a communication signal with the hub unit; And
A photoelectric hybrid cable connecting the hub unit and the remote unit to each other; And,
Wherein the remote unit receives power from the hub unit through the photoelectric hybrid cable. The method according to claim 1,
Wherein the remote unit operates with the power supplied from the hub unit without a separate power source. The method according to claim 1,
Wherein the hub unit includes a power supply unit capable of supplying power to the remote unit. The method according to claim 1,
Wherein the remote unit receives an optical signal from the hub unit through the photoelectric hybrid cable and converts the optical signal into an electrical signal. The method according to claim 1,
And the communication signal is transmitted / received between the hub unit and the remote unit via the photoelectric hybrid cable. The method according to claim 1,
Wherein the photoelectric composite cable comprises:
An optical cable disposed at the center of the photoelectric hybrid cable;
At least one first power line unit and at least one second power line unit surrounding and surrounding the optical cable; And
An envelope layer surrounding the first power line units and the second power line units; And,
The optical cable includes:
A buffer tube disposed at the center of the optical cable;
At least one optical fiber unit including a plastic tube assembled longitudinally around the buffer tube and an optical fiber core wire mounted in the plastic tube; And
A sheath layer surrounding the optical fiber unit; / RTI >
Wherein one of said first power line unit, said one second power line unit, and one of said optical fiber units is branched and connected to one of said remote units. The method according to claim 6,
Wherein the buffer tube has a diameter circumscribing each of the at least one optical fiber unit and capable of stably supporting the optical fiber unit. The method according to claim 6,
Wherein the plastic tube is made of polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide (PA), or a combination thereof. 9. The method of claim 8,
Wherein the buffer tube is made of a foamed plastic resin having a lower strength than the plastic tube. The method according to claim 6,
Wherein a waterproof material including a jelly compound, a waterproof powder, a waterproofing yarn, or a combination thereof is mounted in the plastic tube together with the optical fiber core wire. The method according to claim 6,
And the power is supplied to the remote unit through the power line. The method according to claim 6,
And the communication signal is transmitted / received between the hub unit and the remote unit via the optical cable. The method according to claim 1,
Wherein the photoelectric composite cable includes a first power source line unit, a second power source line unit, and a ground line, an outer layer surrounding and surrounding the first power source line unit and the second power source line unit or the ground line, And an optical fiber unit in contact with the outer skin layer. The method according to claim 1,
The master unit includes:
An A / D converter for digitally converting an incoming signal from the base station to generate a signal sample;
A signal detector for determining whether a communication signal is received based on the signal samples; And
And a mode controller for setting an operation mode based on the determination result of the reception. 15. The method of claim 14,
Further comprising a communication mode determination unit for determining a communication mode of the incoming signal. 16. The method of claim 15,
Wherein the mode control unit sets the operation mode based on whether or not the communication signal is received and the determination result of the communication method. 16. The method of claim 15,
Wherein the communication mode determination unit determines a communication mode of the incoming signal for each service frequency band. 15. The method of claim 14,
Wherein the signal detection unit determines whether or not the communication signal is received for each service frequency band. 15. The method of claim 14,
Wherein the mode control unit operates only when the communication signal is received in the signal detection unit. 15. The method of claim 14,
And a signal input / output unit connected to the base station by wire to transmit and receive the communication signal. 15. The method of claim 14,
A photoelectric conversion unit for photoelectrically converting the communication signal;
And a light transmission unit for transmitting the photoelectric-converted optical signal in the set operation mode. 15. The method of claim 14,
Wherein the signal detecting unit determines that the communication signal is received when the size of the signal sample is equal to or greater than a preset reference value.

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