KR100338625B1 - Base station transceiver system using wavelength division multiplexing - Google Patents

Abstract

A base station system using a wavelength division multiplexing system according to the present invention comprises: a plurality of small base stations having a switching circuit which is connected to a receivable input terminal by detecting whether the input terminals are received from a photodetector connected to each input terminal; A wavelength division multiplexer for multiplexing optical signals having wavelengths assigned to the small base stations to an output terminal, a switching circuit that detects whether the input terminals are receivable from a photodetector connected to each input terminal and automatically connects them to a receivable input terminal; A main station including a wavelength division demultiplexer for demultiplexing an optical signal input through the switching circuit; An optical splitter connected to the output terminal of the main base station for splitting the optical signal in both directions, an optical isolator provided at both ends of the optical splitter, and a pair of taps connected to the input terminal of the small base station to branch only one optical signal in one direction. A forward optical fiber annular link comprising; And a reverse optical fiber annular link having an open end connected to the output terminal of the small base station and splitting the optical signal in both directions, and having an open end connected to the switching circuit of the main base station.

Description

Base station system using wavelength division multiplexing {BASE STATION TRANSCEIVER SYSTEM USING WAVELENGTH DIVISION MULTIPLEXING}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station tranceiver system, and more particularly, to a base station system using wavelength division multiplexing.

1 is a diagram illustrating a conventional base station system. The base station system is a mobile station (MS 170), a remote repeater (160), a base station (BTS, 140), a control station (BSC, 120), a switch (MSC, 110) and a general telephone network (PSTN, 100). It is composed. The mobile station 170 is a terminal device that allows a subscriber to communicate using a mobile communication network, and the base station 140 is connected to the mobile station 170 in a wireless section to control the mobile station 170 and to have a call channel ( channel). In addition, the control station 120 controls a radio link and a wire link and performs a function of connecting to another communication network. At this time, the control station 120 uses the E1 / T1 link to control the plurality of base stations 140. The installation of a plurality of base stations 140 is enormously expensive and also has a cell 142 which is a limited service area. The cell 142 is classified into a macro cell, a micro cell, a mega cell using a low orbit satellite, and the like according to the service level. In addition, a remote repeater 160 using a subcarrier multiplexing (SCM) has been developed and used for services in areas where it is difficult to install a base station other than the cell 142 and a radio shading area in the cell 142. ought. The remote repeater 160 is a system for responding to operators requiring a wide range of cell coverage at low cost in a low-density call area, and extends a service area formed along a ski resort, golf course or road, far away from the village. In order to secure a service area in an area where the installation of the base station is difficult due to the cost and the expected call volume is not high, the enormous cost of installing the base station in a manner in which a plurality of remote repeaters 160 are installed and managed by one base station 140 is managed. It is a way to reduce the efficiency.

However, in the conventional base station system in which several remote repeaters are installed and managed by one base station to secure a wide service area outside the cell, the optical splitter installed in the base station uses a signal transmitted from the base station using an optical fiber corresponding to the number of remote repeaters. It takes the method of sending and receiving the signal transmitted from the terminal. This method has a disadvantage in that an optical fiber corresponding to the number of repeaters must be installed from a base station.

In this respect, there is a structural weakness in terms of utilization around highways or in buildings. In addition, the parallel installation of the optical fiber has a problem that the installation fee of the optical fiber and the use of the leased line increases. And, the distance between the base station and the repeater is limited, and access between the repeaters is not desired. In terms of installation, the burden on the operator to install the repeater after installation of the base station is given to the operator. As a result, such conventional base station systems are not suitable for high speed large capacity and multimedia services and have difficulties in access and operation between a remote repeater and a base station.

Accordingly, an object of the present invention is to enable high-speed, high-capacity and multimedia services using a digital optical communication network, and economically implements each base station without additionally installing a standard base station and an optical repeater, which requires a large amount of money to install. It is to provide a base station system capable of efficient access.

In order to achieve the above object, a base station system using a wavelength division multiplexing method according to the present invention,

A plurality of small base stations, each having a switching circuit connected to a receivable input terminal by detecting whether the input terminals can be received from a photodetector connected to each input terminal;

A wavelength division multiplexer for multiplexing optical signals having wavelengths assigned to the small base stations to an output terminal, a switching circuit that detects whether the input terminals are receivable from a photodetector connected to each input terminal and automatically connects them to a receivable input terminal; A main station including a wavelength division demultiplexer for demultiplexing an optical signal input through the switching circuit;

An optical splitter connected to the output terminal of the main base station for splitting the optical signal in both directions, an optical isolator provided at both ends of the optical splitter, and a pair of taps connected to the input terminal of the small base station to branch the optical signal in one direction A forward optical fiber annular link comprising a;

And a reverse optical fiber annular link having an open end connected to the output terminal of the small base station and splitting the optical signal in both directions, and having an open end connected to the input terminal of the main base station.

1 is a view showing a conventional base station system,

2 is a diagram illustrating a base station system using wavelength division multiplexing according to a preferred embodiment of the present invention;

3 illustrates a forward link of a base station system according to a preferred embodiment of the present invention;

4 illustrates a reverse link of a base station system according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

2 is a diagram illustrating a base station system using wavelength division multiplexing according to a preferred embodiment of the present invention. The base station system is a system manager that integrates and manages one main base station 220 integrating the functions of a plurality of base stations, a control station 200 for controlling the base station, and components of the main base station 220. And a plurality of optical fiber annular links 260 connecting the main base station 220 and the plurality of small base stations 270, respectively.

The control station 200 controls all connected lower wired and wireless links and performs a connection with another communication network.

The main station 220 includes a signal processor 230 for transmitting and receiving to and from the control station 200, a signal converter 240 for converting an input electrical signal or an optical signal into an optical signal or an electrical signal, and an input optical signal. It consists of an optical transmitter 250 for outputting multiplexed or demultiplexed by wavelength. The signal processor 230 includes a plurality of signal processors 232 performing the same function. The signal converter 240 includes a plurality of signal converters 242 each performing the same function, and the signal converter 242 corresponding to the signal processor 232 in one-to-one correspond to an input electrical signal or an optical signal. Converts to an optical signal or an electrical signal. The optical transmitter 250 receives a wavelength division multiplexer 252 for multiplexing and outputting optical signals input from the signal converter 240 to a single output optical fiber 262 and a pair of input optical fibers 264. A switching circuit 256 having a self-healing function which is automatically connected to an input optical fiber, and wavelength division which outputs the signal to the signal converter 240 by demultiplexing the optical signals inputted through the switching circuit 256 for each wavelength. It consists of a demultiplexer 254.

The system manager 210 manages the signal processor 230, the signal converter 240, and the optical transceiver 250 constituting the main station 220 integrally. This is to compensate for the disadvantages of system management as the control station 200 is directly connected only to the signal processor 230 among the components of the main station 220.

The plurality of optical fiber annular links 260 connecting the plurality of small base stations 270 and the main base station 220 are composed of a forward optical fiber annular link 262 and a reverse optical fiber annular link 264, respectively. The link 262 consists of a single optical fiber and the reverse fiber annular link 264 consists of a pair of optical fibers. In this case, the forward and reverse classification criteria are arbitrary, and the optical signal passing through the forward and reverse optical fiber annular links 262 and 264 is always bidirectional with respect to the initial branch point, that is, the branch point 320 where the optical signal first contacts. Will proceed. This is to implement the self-healing function of the optical fiber annular link 260, and the optical fiber does not pass even if a signal disconnection condition such as disconnection occurs at any point of the forward or reverse optical fiber annular link 262 or 264. It is to maintain the communication enabled state as a signal.

The small base station 270 is connected to the optical fiber annular link 260 and the branch point 320, the small base station 270 and the branch point 320 is a pair of input optical fibers 312 and one output optical fiber ( 314). Each of the small base stations 270 is configured to input and output only optical signals having a specific wavelength. The small base station 270 is composed of an optical transceiver 300, a signal converter 290, a signal processor 280, and the transmit and receive antennas 272 and 274. The optical transmitter 300 includes a switching circuit 304 having a self-healing function that is automatically connected to a receivable input optical fiber 312 of the pair of input optical fibers 312, and through the switching circuit 304. A photoelectric conversion unit 302 for converting an input optical signal into an electrical signal, an all-optical conversion unit 306 for converting an input electrical signal into an optical signal, and blocking the optical signal input from the switching circuit 304 It consists of an optical isolator 308. The signal converter 290 includes a digital / analog converter 292 for converting an input digital signal into an analog signal, and an analog / digital converter 294 for converting an input analog signal into a digital signal. The intermediate frequency electric signal input from the signal converter 290 to the signal processor 280 is modulated to a radio frequency while sequentially passing through a filter 283, a UPC 282, and an HPA 281, thereby transmitting antenna 272. The electrical signal of the radio frequency transmitted through the reception antenna 274 is received through the LNA 284, the DNC 285 and the filter 286 in order to be modulated to an intermediate frequency and output to the signal converter 290. do.

The base station system using the wavelength division multiplexing system according to the present invention is easy to build a small base station connected to the optical fiber annular link, and self-healing that can immediately reconfigure the communication network even when a failure occurs at any point of the optical fiber annular link. It is configured to have a function. Each small base station may have a micro or pico cell, and the optical fiber annular link may have a shape other than a circular shape, so that when the small base stations need to be installed in a line, such as around a highway or a tunnel, any link structure may be remote at a distance. It can be used freely when there is a need to install small base stations or when installing small base stations in a dense call area. The optical fiber annular link structure can not only extend the transmission distance of the optical communication network, but also can effectively expand and operate the number of small base stations connected to the main base station by economically extending the limited branch point.

In addition, the base station system according to the present invention is a digital mobile communication system using a code division multiplexing access (CDMA) using a digital optical transmission optical fiber link, personal mobile communication and next-generation mobile communication (IMT2000 or CDMA2000) By applying to a base station system of a large number of small base stations can be easily installed compared to the existing. In addition, the optical fiber annular link according to the present invention is a self-healing communication link capable of adequately handling the required communication demand by immediately reconfiguring the communication link even when a failure occurs at any point, and commercializing it for the purpose of expanding the communication service area. It relates to an optical transmission device and a link structure that can be operated. In the mobile communication base station system, a small base station apparatus using a digital optical communication link enables data communication between a base station and a terminal, and is configured as a system applicable to an existing base station system or a newly installed base station system.

3 is a view showing the structure of a forward optical fiber link according to a preferred embodiment of the present invention. The optical signals output from the plurality of signal converters 412 constituting the signal converter 410 have different wavelengths and are input to the wavelength division multiplexer 414 of the optical transceiver to form a forward optical fiber annular link. Multiplexed to 416. The optical signals output from the wavelength division multiplexer 414 proceed in both directions with respect to the main branch point 420, and the main branch point 420 includes an optical separator 426 and first and second optical isolators ( 422 and 424). The optical separator 426 separates and outputs a plurality of optical signals having different wavelengths input from the wavelength division multiplexer 414 in both directions. First and second optical isolators 422 and 424 are provided at left and right sides of the optical separator 426 to block optical signals in the reverse direction. As an example, a Y-branched optical waveguide can be used as the optical separator 426. If the forward optical fiber annular link is not obstructed, the optical signals passing through the first optical isolator 422 will be blocked by the second optical isolator 424. In addition, in FIG. 3, the first and second unidirectional taps 492 and 494 provided at the third branch point 490 indicate that the optical signal is traveling to the first and second input optical fibers 500 and 505. Each of the unidirectional tabs 492 or 494 serves to branch only an optical signal in a predetermined direction. The first and second input optical fibers 500 and 505 are connected to the optical transceiver 510 of the third small base station, and the switching circuit 520 constituting the optical transceiver 510 is initially input to the first input. It is connected to the optical fiber 500 to receive an optical signal.

Unlike this normal case, when a failure point 450 such as a fiber break occurs in the forward optical fiber annular link connecting the first small base station 440 and the second small base station 470 as shown in FIG. Among the two-way optical signals destined for the third small base station, the optical signal traveling toward the first small base station 440 may not pass through the failure point 450. At this time, the second photodetector 528 that receives the optical signal branched by the second tap 526 connected to the second optical fiber 505 continuously detects the optical signal, but the first input optical fiber ( The first photodetector 524, which receives the optical signal branched by the first tap 522 connected to 500, does not detect any optical signal. At the same time, the switching circuit 520 is automatically connected to the second optical fiber 505 where the optical signal is detected, as no sensing signal is output from the first photodetector 524. That is, by using the first and second photodetectors 524 and 528, the switching circuit 520 can continuously receive the optical signal. The light output from the switching circuit 520 is input to the optical wavelength filter 530 and only an optical signal having a specific wavelength is output. That is, in the third small base station, since a specific input / output wavelength is set, the optical signal having a wavelength other than the specific wavelength must be removed. The photoelectric converter 540 converts an input optical signal into an electrical signal and outputs the electrical signal, which is then input to a digital / analog converter.

Alternatively, an optical amplifier may be installed on the links between the branch points to compensate for optical signal attenuation when the distance between the branch points forming the optical fiber annular link according to the present invention is far. 3 illustrates an optical amplifier 480 installed between the second branch point 460 and the third branch point 490. The optical amplifier 480 includes first and second circulators 482 and 488 and first and second optical amplifiers 484 and 486 to amplify optical signals traveling in both directions. The first and second optical amplifiers 484 and 486 may be formed of an erbium doped fiber, and the erbium-doped optical fiber is input using induction emission of erbium ions excited by pumping light. Amplify the optical signal. The optical signal traveling in the clockwise direction in the forward optical fiber annular link is input to the second optical amplifier 486 by the first circulator 482, and the second optical amplifier 486 is input to the input optical signal. An optical signal is amplified and output to the second circulator 488. The optical signal traveling in the counterclockwise direction in the forward optical fiber annular link is input to the first optical amplifier 484 by the second circulator 488, and the first optical amplifier 484 is input to the input signal. The amplified optical signal is amplified and output to the first circulator 482.

4 is a view showing the structure of a reverse optical fiber annular link according to a preferred embodiment of the present invention. The electrical signal output from the analog / digital switching unit of the third small base station is input to the optical transceiver 730. The optical transceiver 730 is composed of an all-optical conversion unit 734 and an optical isolator 732, the all-optical conversion unit 734 converts the electrical signal into an optical signal and the optical isolator 732 is in the reverse direction Block the optical signal. The optical splitter 720 constituting the third branch point 710 outputs the input optical signal to the first and second taps 712 and 714. Accordingly, the optical signal proceeds in both directions about the branch point 710. As shown in FIG. 4, a failure point 660 may have occurred in the reverse optical fiber annular link connecting the first and second branch points 640 and 690 to the first and second small base stations 650 and 680, respectively. In this case, the optical signal traveling in the counterclockwise direction from the third branch point 710 may not pass through the obstacle point 660. However, since the optical signal traveling in the clockwise direction from the third branch point 710 does not pass through the obstacle point 660, it is input to the switching circuit 620 constituting the main station safely. The switching circuit 620 is connected to the first and second taps 622 and 626 and the first and second taps 622 and 626 respectively connected to the first and second input optical fibers 632 and 634, respectively. And first and second photodetectors 624 and 628 connected. The switching circuit outputs the sensing signal when the same optical signal is not input to both the first and second photodetectors 624 and 628, that is, when only one photodetector 624 or 628 outputs a sensing signal. Photodetectors 624 and 628 are automatically connected to the installed input fiber 632 or 634. That is, in FIG. 4, the switching circuit 620 is connected to the first input optical fiber 632 before the failure point 660 occurs, but after the failure point 660 occurs, the switching circuit 620 occurs. ) Is automatically connected to the second input optical fiber 634. Unlike the case of FIG. 4, if the switching circuit 620 is connected to the second input optical fiber 634 before the failure point 660 occurs, the switching circuit 620 is connected without change. Will remain the same. The optical signal passing through the switching circuit 620 is input to the wavelength division demultiplexer 614 and demultiplexed for each wavelength. The demultiplexed optical signals are input to a signal converter 610 composed of a plurality of signal converters 612.

As described above, the base station system using the wavelength division multiplexing method according to the present invention has the advantage that a high-speed large capacity and multimedia service is possible by transmitting a digital optical signal applying the wavelength division multiplexing to the optical fiber annular link.

In addition, since the optical fiber annular link according to the present invention has a self-healing function, stable signal transmission is possible.

Furthermore, the base station system using the wavelength division multiplexing system according to the present invention is provided with a main base station incorporating conventional base stations and a plurality of small base stations connected by an optical fiber annular link, thereby enabling the expansion of the small base station and the efficient access of each small base station. There is an advantage.

Claims (8)

In the base station system using a wavelength division multiplexing system, A plurality of small base stations, each having a switching circuit connected to a receivable input terminal by detecting whether the input terminals can be received from a photodetector connected to each input terminal; A wavelength division multiplexer for multiplexing optical signals having wavelengths assigned to the small base stations to an output terminal, a switching circuit that detects whether the input terminals are receivable from a photodetector connected to each input terminal and automatically connects them to a receivable input terminal; A main station including a wavelength division demultiplexer for demultiplexing an optical signal input through the switching circuit; An optical splitter connected to an output terminal of the main base station for splitting an optical signal in both directions, an optical isolator provided at both ends of the optical splitter, and a pair of unidirectional ones respectively connected to an input terminal of the small base station to branch only one optical signal; A forward optical fiber annular link comprising a tab; And a reverse optical fiber annular link having an open end connected to an output terminal of the small base station and splitting an optical signal in both directions, and having an open end connected to the switching circuit of the main base station. Base station system using. The method of claim 1, And an optical amplifier for amplifying an optical signal traveling along the forward or reverse optical fiber annular link. The method of claim 2, wherein the optical amplifier, First and second optical fiber amplifiers for amplifying optical signals traveling along forward and reverse optical fiber annular links, respectively; A first circulator for distributing an optical signal traveling along the forward optical fiber annular link to the second optical fiber amplifier; And a second circulator for distributing an optical signal traveling along the reverse optical fiber annular link to the first optical fiber amplifying unit. The method of claim 1, And a control station for controlling transmission and reception of all optical signals going through the forward and reverse optical fiber annular links, and connecting to other communication networks. The method of claim 4, wherein the main base station, A signal processor for transmitting and receiving to and from the control station; And a signal converter for converting an input electrical signal or an optical signal into an optical signal or an electrical signal. The method of claim 5, Using a wavelength division multiplexing method, further comprising a system manager for integrally managing the interaction between the signal processor, the signal converter, the switching circuit, the wavelength division multiplexer, and the wavelength division demultiplexer constituting the main base station. Base station system. The method of claim 1, wherein the small base station, A photoelectric conversion unit converting the optical signal input through the switching circuit into an electrical signal; An optical isolator for blocking an optical signal input through the reverse optical fiber annular link; And an all-optical converting unit converting the input electric signal into an optical signal and outputting the optical signal to the optical isolator. The method of claim 7, wherein the small base station, A signal converter converting the digital signal input from the photoelectric converter into an analog signal, and converting the analog signal into a digital signal and outputting the digital signal to the all-optical converter; A signal processor converting the analog signal of the intermediate frequency input from the signal converter into an analog signal of the radio frequency, and converting the analog signal of the radio frequency into an analog signal of the intermediate frequency and outputting the analog signal to the signal converter; And a transmission / reception antenna for transmitting an analog signal of a radio frequency input from the signal processor and outputting an analog signal of a received radio frequency to the signal processor.