Optical communication system and monitoring method thereof

Abstract

To provide an optical communication system and method of monitoring thereof.SOLUTION: An optical communication system configured as an optical ring network includes: a first optical communication device configured to transmit a first optical signal having a first wavelength in a first direction, and to transmit a second optical signal having a second wavelength in a second direction opposite to the first direction; and a second optical communication device configured to generate a first reflected signal by reflecting the first optical signal when the first optical signal is received, to generate a second reflected signal by reflecting the second optical signal when the second optical signal is received, and to transmit the first and second reflected signals to the first optical communication device. The first optical communication device analyzes a connection state of the second optical communication device based on the first and second reflected signals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical communication system and a monitoring method thereof. [Background technology]

[0002] With the emergence of various multimedia services based on the Internet and the web, large volumes of data traffic are increasing, and with the advent of smartphones, the demand for data services is rapidly increasing, which is creating a need for increased transmission capacity in optical communication networks that are applied to wireless access networks for mobile communications, etc.

[0003] As a result, the number of devices constituting optical communication networks has increased, and the complexity of the network structure has become significantly greater, making efficient network management and equipment maintenance important factors. In particular, there is a demand for methods that can detect errors in optical communication network devices to prevent failures and quickly respond to failures when they occur, thereby improving service quality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Korean Patent Publication No. 10-2008-0097795 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an optical communication system and a monitoring method thereof that can efficiently monitor the connection status between optical communication devices that constitute the optical communication system.

[0006] The technical problems that the technical idea of ​​the present invention aims to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided an optical communication device for an optical ring network, comprising: a first optical signal processing unit that outputs a first optical signal of a first wavelength; and a first multiplexer / multiplexer that outputs the first optical signal in a first direction and receives and outputs a first reflected signal that is a signal that is reflected from the first optical signal. De An optical communication device is provided, comprising: a multiplexer (MUX / DEMUX); a second optical signal processing unit that outputs a second optical signal of a second wavelength; a second MUX / DEMUX that outputs the second optical signal in a second direction opposite to the first direction and receives and outputs a second reflected signal that is a reflected signal of the second optical signal; and a controller that analyzes a connection status of a first remote optical communication device to which the first and second optical signals are assigned based on the first and second reflected signals.

[0008] According to an exemplary embodiment, the first remote optical communication device is configured to reflect the first optical signal to generate the first reflected signal, reflect the second optical signal to generate the second reflected signal, and transmit the generated first and second reflected signals to the optical communication device, but is configured to generate a corresponding reflected signal only when the first or second optical signal is received in a predetermined direction of the first and second directions.

[0009] According to an exemplary embodiment, the controller determines that a connection error has occurred in the first remote optical communication device if only one of the first and second reflected signals is received.

[0010] According to an exemplary embodiment, the optical communication device further includes a third optical signal processor that outputs a third optical signal of a third wavelength to the first MUX / DEMUX and a fourth optical signal processor that outputs a fourth optical signal of a fourth wavelength to the second MUX / DEMUX, wherein the first MUX / DEMUX multiplexes the first optical signal and the third optical signal and outputs the multiplexed signal in the first direction, receives a third reflected signal that is a reflected signal of the third optical signal, and outputs the multiplexed signal to the controller, the second MUX / DEMUX multiplexes the second optical signal and the fourth optical signal and outputs the multiplexed signal in the second direction, and receives a fourth reflected signal that is a reflected signal of the fourth optical signal, and outputs the multiplexed signal to the controller, and the controller analyzes the connection status of a second remote optical communication device to which the third and fourth optical signals are assigned based on the third and fourth reflected signals.

[0011] According to an exemplary embodiment, the second remote optical communication device is configured to reflect the third optical signal to generate the third reflected signal, reflect the fourth optical signal to generate the fourth reflected signal, and transmit the third and fourth reflected signals to the optical communication device, but is configured to generate a corresponding reflected signal only if the third or fourth optical signal is received in a predetermined direction among the first and second directions.

[0012] According to an exemplary embodiment, the controller determines that a connection error of the second remote optical communication device has occurred if only one of the third and fourth reflected signals is received.

[0013] According to another aspect of the present invention, there is provided an optical communication system configured with an optical ring network, comprising: a first optical communication device that transmits a first optical signal of a first wavelength in a first direction and transmits a second optical signal of a second wavelength in a second direction opposite to the first direction; and a second optical communication device that, when the first optical signal is received, reflects the first optical signal to generate a first reflected signal, and when the second optical signal is received, reflects the second optical signal to generate a second reflected signal, and transmits the first and second reflected signals to the first optical communication device, wherein the first optical communication device analyzes a connection status of the second optical communication device based on the first and second reflected signals.

[0014] According to an exemplary embodiment, the second optical communication device is configured to generate a corresponding reflected signal only when the first or second optical signal is received in a predetermined one of the first and second directions.

[0015] According to an exemplary embodiment, the first optical communication device determines that a connection error has occurred in the second optical communication device if only one of the first and second reflected signals is received.

[0016] According to an exemplary embodiment, the first optical communication device transmits a third optical signal of a third wavelength in the first direction and a fourth optical signal of a fourth wavelength in the second direction, and the optical communication system further includes a third optical communication device that, when the third optical signal is received, reflects the third optical signal to generate a third reflected signal, and when the fourth optical signal is received, reflects the fourth optical signal to generate a fourth reflected signal, and transmits the third and fourth reflected signals to the first optical communication device, and the first optical communication device analyzes the connection status of the third optical communication device based on the third and fourth reflected signals.

[0017] According to an exemplary embodiment, the third optical communication device is configured to generate a corresponding reflected signal only when the third or fourth optical signal is received in a predetermined direction of the first and second directions.

[0018] According to an exemplary embodiment, the first optical communication device determines that a connection error has occurred in the third optical communication device if only one of the third and fourth reflected signals is received. [Effects of the Invention]

[0019] According to the present invention, the connection status between optical communication devices can be efficiently monitored.

[0020] The effects obtained by the embodiments according to the technical concept of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a configuration diagram of an optical communication system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram of a COT according to an embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram of an RN according to an embodiment of the present invention. [Figure 4] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 5] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 6] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 7] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 8] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 9] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 10] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 11] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 12] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 13] 1 is a diagram illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system. [Figure 14] 10 is a diagram illustrating a connection status monitoring table according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The technical concept of the present invention can be variously modified and can have various embodiments, and therefore, specific embodiments are illustrated in the drawings and will be described in detail. However, this is not intended to limit the technical concept of the present invention to the specific embodiments, and it should be understood that the technical concept of the present invention includes all modifications, equivalents, and alternatives that fall within the scope of the technical concept of the present invention.

[0023] In explaining the technical concept of the present invention, if a detailed description of the related prior art is deemed to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Furthermore, numbers (e.g., 1, 2, etc.) used in the description of this specification are merely identification symbols for distinguishing one component from another.

[0024] Furthermore, in this specification, when a component is referred to as being "coupled" or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but may also be coupled or connected via another component in between, unless otherwise specified to the contrary.

[0025] In addition, terms such as "module", "device" and "subsystem" used in this specification refer to a unit that processes at least one function or operation, and this may be embodied in hardware or software, such as a processor, microprocessor, microcontroller, CPU (Central Processing Unit), GPU (Graphics Processing Unit), APU (Accelerate Processor Unit), DSP (Drive Signal Processor), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), or a combination of hardware and software.

[0026] It should be understood that the division of components in this specification merely represents a division according to the main function of each component. That is, two or more components described below may be combined into one component, or one component may be divided into two or more components according to further subdivided functions. It goes without saying that each component described below may perform some or all of the functions of other components in addition to its own main function, and that some of the main functions of each component may be exclusively performed by other components.

[0027] Hereinafter, various embodiments according to the technical concept of the present invention will be described in detail.

[0028] FIG. 1 is a configuration diagram of an optical communication system according to an embodiment of the present invention. Referring to FIG. 1, the optical communication system 100 according to an embodiment of the present invention includes a Central Office Terminal (COT) 110 and n Remote Nodes (RNs) 120-1 to 120-n (where n is a natural number). Hereinafter, an application example will be described in which the COT and the n Remote Nodes 120-1 to 120-n constitute an optical transport network, which is a subnetwork constituting a fronthaul segment of a radio access network architecture. However, the technical concept of the present invention is not limited thereto. It is clear that the technical concept of the present invention can also be applied to optical transport networks such as midhaul and backhaul segments of a radio access network architecture, as well as FTTx solutions and in-building solutions.

[0029] The COT 110 and the n RNs 120-1 to 120-n are connected to each other in a ring topology to form an optical ring network.

[0030] The connection structure will be described in more detail assuming that the optical communication system 100 according to an embodiment of the present invention is configured with a COT 110 and two RNs 120-1 and 120-2. The COT 110 and the two RNs 120-1 and 120-2 each have an input / output port for connection therebetween. A first optical cable is connected to the first input / output port of the COT 110, and a second optical cable is connected to the second input / output port of the COT 110. A first optical cable is connected to the first input / output port of the first RN 120-1, and a third optical cable is connected to the second input / output port of the first RN 120-1. A third optical cable is connected to the first input / output port of the second RN 120-2, and a second optical cable is connected to the second input / output port of the second RN 120-2. The first, second, and third optical cables refer not only to a single optical cable but also to multiple optical cables and their connection structures.

[0031] Meanwhile, of the interconnected COT and two RNs, the COT is connected to a part of the base station that performs digital processing, for example, at least one DU (Digital Unit) (or BBU (BaseBand Unit)), in the fronthaul segment of the radio access network architecture, and each RN is connected to a part of the base station that performs radio processing, for example, at least one RU (Radio Unit) (or RRH (Remote Radio Head)). However, without being limited thereto, of the interconnected COT and two RNs, the COT is connected to at least one small cell RU, and each RN is connected to at least one small cell RU. The connection targets and interconnection structures of the COT and RNs vary according to various fronthaul topologies of the radio access network architecture.

[0032] The COT 110 is a device that multiplexes base station signals and transmits them to one or more of the connected RNs 120-1 through 120-n. For example, the COT 110 receives signals from a DU (not shown), converts them into WDM signals, and transmits the WDM signals to one or more of the connected RNs 120-1 through 120-n via an optical cable. That is, the COT 110 is a device that receives multiple base station signals, converts them into optical signals with different wavelengths, and transmits the optical signals to one or more RNs (120-1 through 120-n). The base station signals are baseband signals based on fronthaul link standards such as Common Public Radio Interface (CPRI), Open Base Station Architecture Initiative (OBSAI), and Open Radio Equipment Interface (ORI).

[0033] In the example of FIG. 1, COT 110 transmits WDM signals in one direction of the ring network, i.e., through a first optical cable, to a first RN 120-1, and in the other direction of the ring network, i.e., through a second optical cable, to an nth RN 120-n.

[0034] Each of the RNs 120-1 to 120-n is a device located at a remote cell site. Each of the RNs 120-1 to 120-n is connected to the COT 110 and transmits the WDM signal received from the COT 110 to at least one RU (not shown) connected thereto. That is, each of the RNs 120-1 to 120-n is a passive WDM device. Alternatively, each of the RNs may be replaced by a Remote Terminal (RT). Various remote devices may be used depending on the optical transmission network field to which the optical communication system 100 is applied.

[0035] According to an embodiment of the present invention, the COT 110 analyzes the connection status between the COT 110 and the first RN 120-1 and the COT 110 and the second RN 120-2 using an optical signal corresponding to a base station signal and a monitoring optical signal having a separate wavelength (i.e., channel). For example, the COT 110 transmits the monitoring optical signal to the first RN 120-1 and / or the second RN 120-2 and analyzes the monitoring optical signal reflected back from the first RN 120-1 and / or the second RN 120-2 to analyze the connection status between the COT 110 and the first RN 120-1 and the COT 110 and the second RN 120-2.

[0036] Hereinafter, the operation performed by the COT 110 to analyze the connection status between the COT 110 and the first and second RNs 120-1 and 120-2 will be described in more detail.

[0037] Fig. 2 is a block diagram of a COT according to an embodiment of the present invention, and Fig. 3 is a block diagram of an RN according to an embodiment of the present invention. For convenience of explanation, Fig. 2 and Fig. 3 illustrate the main components for monitoring among the components of the COT and RN.

[0038] The COT 110 according to an embodiment of the present invention includes first through fourth optical signal processors 210 through 240, a controller (MCU) 250, and first and second MUX / DEMUXs 260 and 270. While Fig. 2 illustrates an embodiment in which the COT 110 includes four optical signal processors and two MUX / DEMUXs, the number of optical signal processors and MUX / DEMUXs may be varied in various ways. For example, the number of optical signal processors increases depending on the number of RNs.

[0039] The first to fourth optical signal processing units 210 to 240 each generate an optical signal for monitoring under the control of the controller (MCU) 250, and output the generated optical signal to a corresponding MUX / DEMUX among the first and second MUX / DEMUXs 260 and 270.

[0040] The first optical signal processing unit 210 generates a first optical signal of a first wavelength λ1 and outputs it to the first MUX / DEMUX 260. The second optical signal processing unit 220 generates a second optical signal of a second wavelength λ2 and outputs it to the second MUX / DEMUX 270. The third optical signal processing unit 230 generates a third optical signal of a third wavelength λ3 and outputs it to the first MUX / DEMUX 260. The fourth optical signal processing unit 240 generates a fourth optical signal of a fourth wavelength λ4 and outputs it to the second MUX / DEMUX 270.

[0041] The first through fourth wavelengths λ1 through λ4 may be wavelengths different from the wavelengths used to transmit base station signals. For example, the first through fourth wavelengths λ1 through λ4 may be different from the wavelength λRN1 of the base station signal transmitted to the first RN 120-1 and the wavelength λRN2 of the base station signal transmitted to the second RN 120-2. That is, while FIG. 2 and the following description illustrate one wavelength of the base station signal assigned to the first RN 120-1 and one wavelength of the base station signal assigned to the second RN 120-2 for the sake of convenience, the first and second RNs 120-1 and 120-2 may each have a plurality of wavelengths of the base station signal.

[0042] The first wavelength λ1, the second wavelength λ2, the third wavelength λ3, and the fourth wavelength λ4 are wavelengths in the same band. For example, the first wavelength λ1 is a wavelength in the L band at 1310 nm, and the second wavelength λ2 is a wavelength in the H band at 1310 nm. The third wavelength λ3 is a wavelength in the L band at 1370 nm, and the fourth wavelength λ4 is a wavelength in the H band at 1370 nm.

[0043] The first wavelength λ1 and the second wavelength λ2 are supervisory wavelengths assigned to the first RN 120-1, and the third wavelength λ3 and the fourth wavelength λ4 are supervisory wavelengths assigned to the second RN 120-2. Such supervisory wavelengths may be wavelengths of a supervisory channel or the like.

[0044] The first through fourth optical signal processing units 210 through 240 each include an optical transceiver (e.g., an XFP, SFP, QSFP, or CFP type optical transceiver), a signal coupler (e.g., a coupler), and a filter to generate an optical signal of a wavelength set under the control of the controller 250 and output the optical signal to a corresponding one of the first and second MUX / DEMUXs 260 and 270. In this case, the optical transceiver is a wavelength-tunable optical transceiver, and has a structure in which the transmit port and receive port of the optical transceiver are connected to the signal coupler, the signal coupler and the filter are connected to the corresponding MUX / DEMUX.

[0045] Depending on the embodiment, the first to fourth optical signal processing units 210 to 240 may be configured as filters for outputting optical signals of a predetermined wavelength received from an external device to corresponding MUX / DEMUXs among the first and second MUX / DEMUXs 260 and 270.

[0046] The first MUX / DEMUX 260 multiplexes a service optical signal corresponding to a base station signal for the first and second RNs 120-1 and 120-2 with the first and third optical signals, and outputs a first WDM signal to the connected first optical cable. Hereinafter, the direction of transmission of the optical signal through the first MUX / DEMUX 260 will be referred to as "E" (EAST).

[0047] The second MUX / DEMUX 270 multiplexes the service optical signal corresponding to the base station signal for the first and second RNs 120-1 and 120-2 with the second and fourth optical signals, and outputs a second WDM signal to the connected second optical cable. Hereinafter, the direction of transmission of the optical signal through the second MUX / DEMUX 270 will be referred to as "W" (WEST).

[0048] The first MUX / DEMUX 260 outputs a reflected signal received through the first optical cable after transmitting the first WDM signal to the controller 250. The second MUX / DEMUX 270 outputs a reflected signal received through the second optical cable after transmitting the second WDM signal to the controller 250.

[0049] As described above, the controller 250 controls the overall operation of the first to fourth optical signal processing units 210 to 240 and / or the COT 110, analyzes the reflected signals input from the first MUX / DEMUX 260 and / or the second MUX / DEMUX 270, and analyzes the connection status of one or more RNs 120-1 to 120-n that constitute the optical communication system 100.

[0050] 3, the first RN 120-1 includes a first bandpass filter 310, a first wavelength filter 350-1, a first signal reflector 360-1, a second bandpass filter 320, a second wavelength filter 350-2, a second signal reflector 360-2, and a first RN MUX / DEMUX 370-1. The second RN 120-2 includes a third bandpass filter 330, a third wavelength filter 350-3, a third signal reflector 360-3, a fourth bandpass filter 340, a fourth wavelength filter 350-4, a fourth signal reflector 360-4, and a second RN MUX / DEMUX 370-2.

[0051] The first bandpass filter 310 and the second bandpass filter 320 of the first RN 120-1 are connected together, the third bandpass filter 330 and the fourth bandpass filter 340 of the second RN 120-2 are connected together, and the second bandpass filter 320 and the third bandpass filter 330 are connected together, so that the COT 110 and the first and second RNs 120-1 and 120-2 have a ring topology structure capable of transmitting and receiving optical signals in both directions.

[0052] Although not shown, in the first RN 120-1, the outputs of the first band filter 310 and the second band filter 320 are coupled to a signal combiner (e.g., a coupler), which combines the outputs of the first band filter 310 and the second band filter 320 and outputs the combined signal to the first RN MUX / DEMUX 370-1. Similarly, in the second RN 120-2, the outputs of the third band filter 330 and the fourth band filter 340 are coupled to a signal combiner, which combines the outputs of the third band filter 330 and the fourth band filter 340 and outputs the combined signal to the second RN MUX / DEMUX 370-2.

[0053] The first band pass filter 310 includes a BPF (Band Pass Filter) that filters a band including the wavelength λRN1 of the base station signal assigned to the first RN 120-1, the first wavelength λ1, and the second wavelength λ2.

[0054] When the first band filter 310 receives the first WDM signal, it filters the service optical signal and the first optical signal assigned to the first RN 120-1 from the first WDM signal and outputs the result to the first wavelength filter 350-1 and the first RN MUX / DEMUX 370-1. Alternatively, when the first band filter 310 receives a second WDM signal, it filters the service optical signal and the second optical signal assigned to the first RN 120-1 from the second WDM signal and outputs them to the first wavelength filter 350-1 and the first RN MUX / DEMUX 370-1.

[0055] The first wavelength filter 350-1 includes a wavelength selection filter that filters the first wavelength λ1 and the second wavelength λ2 bands. The first wavelength filter 350-1 filters the first optical signal or the second optical signal from the output of the first band filter 310, and outputs the filtered first optical signal or the second optical signal to the first signal reflector 360-1.

[0056] The first signal reflector 360-1 reflects the optical signal output from the first wavelength filter 350-1 and outputs it in the opposite direction. For example, the first signal reflector 360-1 outputs a reflected signal of the first optical signal (hereinafter referred to as a first reflected signal) or a reflected signal of the second optical signal (hereinafter referred to as a second reflected signal) to the first wavelength filter 350-1.

[0057] The first wavelength filter 350-1 outputs the first reflected signal or the second reflected signal to the first bandpass filter 310. The first bandpass filter 310 transmits the first reflected signal to the first MUX / DEMUX 260 of the COT 110 through the connected optical cable, and transmits the second reflected signal to the second MUX / DEMUX 270 of the COT 110 through the second RN 120-2.

[0058] Similar to the first band-pass filter 310, the second band-pass filter 320 includes a BPF that can filter a band including the wavelength λRN1 of the base station signal assigned to the first RN 120-1, the first wavelength λ1, and the second wavelength λ2.

[0059] When the second WDM signal is received, the second band filter 320 filters the service optical signal and the second optical signal assigned to the first RN 120-1 from the second WDM signal and outputs the result to the second wavelength filter 350-2 and the first RN MUX / DEMUX 370-1.

[0060] Alternatively, when the second band filter 320 receives the first WDM signal, it filters the service optical signal corresponding to the base station signal for the first RN 120-1 and the first optical signal from the first WDM signal and outputs the result to the second wavelength filter 350-2 and the first RN MUX / DEMUX 370-1.

[0061] The second band-pass filter 320 outputs the unfiltered wavelength band to the first band-pass filter 310 and the third band-pass filter 330 of the second RN 120-2.

[0062] The second wavelength filter 350-2 includes a wavelength selection filter that filters the second wavelength λ2 band. The second wavelength filter 350-2 filters the second optical signal from the output of the second band filter 320 and outputs the filtered second optical signal to the second signal reflector 360-2.

[0063] The second signal reflector 360-2 reflects the optical signal output from the second wavelength filter 350-2 and outputs it in the opposite direction, that is, the second signal reflector 360-2 outputs the second reflected signal to the second wavelength filter 350-2.

[0064] The second wavelength filter 350-2 outputs the second reflected signal to the second band filter 320. The second band filter 320 transmits the second reflected signal to the second MUX / DEMUX 270 of the COT 110 via the coupled optical cable and the second RN 120-2.

[0065] Unlike the first wavelength filter 350-1, the second wavelength filter 350-2 filters only signals of a specific wavelength, i.e., the second optical signal. Therefore, when the second bandpass filter 320 is connected to the second MUX / DEMUX 270 of the COT 110 through the optical cable and the second RN 120-2 and the second WDM signal is not input, and when the second bandpass filter 320 is connected to the first MUX / DEMUX 260 of the COT 110 through the optical cable and the first WDM signal is input, no reflected signal is generated by the second wavelength filter 350-2 and the second signal reflector 360-2. Based on these characteristics, the COT 110 detects a change in the connection status of the first RN 120-1.

[0066] Meanwhile, the first RN MUX / DEMUX 370-1 multiplexes the service optical signals output from the first band filter 310 and / or the second band filter 320 and transmits the multiplexed signal to at least one connected RU (not shown). At this time, the first optical signal or the second optical signal may be filtered by the first RN MUX / DEMUX 370-1 and not transmitted to the RU.

[0067] The second RN 120-2 has a configuration corresponding to the first RN 120-1 described above and operates similarly.

[0068] In particular, the second RN 120-2 is configured such that the fourth wavelength filter 350-4 filters the third optical signal and the fourth optical signal corresponding to the third wavelength λ3 and the fourth wavelength λ4, and the third wavelength filter 350-3 filters only the third optical signal corresponding to the third wavelength λ3, and when the connection state between the COT 110 and the second RN 120-2 is reversed, no reflected signal is generated in a specific direction.

[0069] In other words, if the third bandpass filter 330 is connected to the first MUX / DEMUX 260 of the COT 110 via the optical cable and the first RN 120-1 and the first WDM signal is not input, and if the third bandpass filter 330 is connected to the second MUX / DEMUX 270 of the COT 110 via the optical cable and the second WDM signal is input, no reflected signal is generated by the third wavelength filter 350-3 and the third signal reflector 360-2. Based on these characteristics, the COT 110 detects a change in the connection status of the second RN 120-2.

[0070] The controller 250 analyzes the received reflected signal from among the first reflected signal to the fourth reflected signal, and analyzes the connection status between the COT 110 and the first RN 120-1 and the COT 110 and the second RN 120-2.

[0071] For example, the controller 250 analyzes whether the corresponding first reflected signal and / or second reflected signal is received after the first optical signal and / or the second optical signal are transmitted in different directions from the COT 110 and the time until they are received, to determine whether the first RN 120-1 is connected normally (e.g., the connection direction, etc.) and the distance to the first RN 120-1, etc.

[0072] In addition, the controller 250 analyzes whether the corresponding third reflected signal and / or fourth reflected signal is received and the time until it is received after the third optical signal and / or the fourth optical signal are transmitted in different directions from the COT 110, and determines whether the second RN 120-2 is normally connected (e.g., the connection direction, etc.) and the distance to the second RN 120-2, etc.

[0073] The operation of the controller 250 to analyze the connection status of the RNs (120-1 to 120-n) will be described in detail with reference to FIGS.

[0074] 4 to 13 are diagrams illustrating a first connection state (CASE 1) to a tenth connection state (CASE 10) of an optical communication system, and FIG. 14 is a diagram illustrating a connection state monitoring table according to an embodiment of the present invention.

[0075] 4, a case is illustrated in which the 'E' direction of the COT 110 is connected to the 'W' direction of the first RN 120-1, and the 'W' direction of the COT 110 is connected to the 'E' direction of the second RN 120-2 (CASE 1). In this case, the COT 110 and the first RN 120-1 are connected via a first optical cable, the COT 110 and the second RN 120-2 are connected via a second optical cable, and the first RN 120-1 and the second RN 120-2 are connected via a third optical cable.

[0076] 3, the first band pass filter 310 of the first RN 120-1 is connected in the 'W' direction of the first RN 120-1, so that the first WDM signal is input to the first band pass filter 310 of the first RN 120-1. In this case, a first reflected signal is generated through the first band pass filter 310, the first wavelength filter 350-1, and the first signal reflector 360-1, and the generated first reflected signal is output to the first band pass filter 310 and transmitted to the COT 110 through the first optical cable.

[0077] 3, the second band filter 320 of the first RN 120-1 is connected in the 'E' direction of the first RN 120-1, so that the second WDM signal is input to the second band filter 320 of the first RN 120-1. In this case, a second reflected signal is generated through the second band filter 320, the second wavelength filter 350-2, and the second signal reflector 360-2, and the generated second reflected signal is output to the second band filter 320. The second reflected signal is transmitted to the COT 110 via the third optical cable, the second RN 120-2, and the second optical cable.

[0078] 3, the third band filter 330 of the second RN 120-2 is connected in the 'W' direction of the second RN 120-2, so that the first WDM signal is input to the third band filter 330 of the second RN 120-2. In this case, a third reflected signal is generated through the third band filter 330, the third wavelength filter 350-3, and the third signal reflector 360-3, and the generated third reflected signal is output to the third band filter 330. The third reflected signal is transmitted to the COT 110 via the third optical cable, the first RN 120-1, and the second optical cable.

[0079] 3, the fourth band filter 340 of the second RN 120-2 is connected in the 'E' direction of the second RN 120-2, so that the second WDM signal is input to the fourth band filter 340 of the second RN 120-2. In this case, a fourth reflected signal is generated through the fourth band filter 340, the fourth wavelength filter 350-4, and the fourth signal reflector 360-4, and the generated fourth reflected signal is output to the fourth band filter 340 and transmitted to the COT 110 through the second optical cable.

[0080] The controller 250 compares the received reflected signal with a predefined connection status monitoring table to determine the connection status of the first RN 120-1 and the second RN 120-2.

[0081] In the example shown in FIG. 4, the controller 250 receives all of the first through fourth reflected signals, and in this case, the controller 250 determines that the first RN 120-1 and the second RN 120-2 are both normally connected.

[0082] 5, a case is illustrated in which the 'E' direction of the COT 110 is connected to the 'W' direction of the second RN 120-2, and the 'W' direction of the COT 110 is connected to the 'E' direction of the first RN 120-2 (CASE 2). In this case, the COT 110 and the second RN 120-2 are connected via a first optical cable, the COT 110 and the first RN 120-1 are connected via a second optical cable, and the first RN 120-1 and the second RN 120-2 are connected via a third optical cable.

[0083] 3, the first band pass filter 310 of the first RN 120-1 is connected in the 'W' direction of the first RN 120-1, and a first WDM signal is input to the first band pass filter 310 of the first RN 120-1. In this case, a first reflected signal is generated through the first band pass filter 310, the first wavelength filter 350-1, and the first signal reflector 360-1, and the generated first reflected signal is output to the third optical cable on the first band pass filter 310 side. The first reflected signal transmitted to the third optical cable is transmitted to the COT 110 via the second RN 120-2 and the first optical cable.

[0084] 3, the second band filter 320 of the first RN 120-1 is connected in the 'E' direction of the first RN 120-1, so that the second WDM signal is input to the second band filter 320 of the first RN 120-1. In this case, a second reflected signal is generated through the second band filter 320, the second wavelength filter 350-2, and the second signal reflector 360-2, and the generated second reflected signal is transmitted to the COT 110 through the second optical cable on the second band filter 320 side.

[0085] 3, the third band filter 330 of the second RN 120-2 is connected in the 'W' direction of the second RN 120-2, so that the first WDM signal is input to the third band filter 330 of the second RN 120-2. In this case, a third reflected signal is generated through the third band filter 330, the third wavelength filter 350-3, and the third signal reflector 360-3, and the generated third reflected signal is transmitted to the COT 110 through the first optical cable on the third band filter 330 side.

[0086] 3, the fourth band filter 340 of the second RN 120-2 is connected in the 'E' direction of the second RN 120-2, so that the second WDM signal is input to the fourth band filter 340 of the second RN 120-2. In this case, a fourth reflected signal is generated through the fourth band filter 340, the fourth wavelength filter 350-4, and the fourth signal reflector 360-4, and the generated fourth reflected signal is output to the third optical cable on the fourth band filter 340 side. The fourth reflected signal transmitted to the third optical cable is transmitted to the COT 110 via the first RN 120-1 and the second optical cable.

[0087] In this case, the controller 250 also receives all of the first through fourth reflected signals and determines that the first RN 120-1 and the second RN 120-2 are normally connected.

[0088] 6, a case where the 'E' direction of the COT 110 is connected to the 'W' direction of the first RN 120-1 is illustrated (CASE 3). In this case, the COT 110 and the first RN 120-1 are connected via the first and second optical cables, but the COT 110 and the second RN 120-2 are not connected.

[0089] The first bandpass filter 310 of the first RN 120-1 is connected in the 'W' direction of the first RN 120-1 as illustrated in FIG. 3, so that when a first WDM signal is input to the first bandpass filter 310 of the first RN 120-1, a first reflected signal is generated and transmitted to the COT 110 through the first optical cable.

[0090] In addition, the second band filter 320 of the first RN 120-1 is connected in the 'E' direction of the first RN 120-1 as illustrated in FIG. 3, so that when a second WDM signal is input to the second band filter 320 of the first RN 120-1, a second reflected signal is generated and transmitted to the COT 110 through the second optical cable.

[0091] In this case, the controller 250 may receive the first and second reflected signals but not the third and fourth reflected signals, and therefore determine that the first RN 120-1 is normally connected and the second RN 120-2 is not present.

[0092] 7, a case where the 'E' direction of the COT 110 is connected to the 'W' direction of the second RN 120-2 is illustrated (CASE 4). In this case, the COT 110 and the second RN 120-2 are connected via the first and second optical cables, and the COT 110 and the first RN 120-1 are not connected.

[0093] The third band filter 330 of the second RN 120-2 is connected in the 'W' direction of the second RN 120-2 as illustrated in FIG. 3, so that when the first WDM signal is input to the third band filter 330 of the second RN 120-2, a third reflected signal is generated and transmitted to the COT 110 through the first optical cable.

[0094] In addition, since the fourth band filter 340 of the second RN 120-2 is connected in the 'E' direction of the second RN 120-2, when a second WDM signal is input to the fourth band filter 340 of the second RN 120-2, a fourth reflected signal is generated and transmitted to the COT 110 through the second optical cable.

[0095] In this case, controller 250 may receive the third and fourth reflected signals but not the first and second reflected signals, and therefore determine that second RN 120-2 is normally connected and first RN 120-1 is not present.

[0096] 8, a case is illustrated in which the 'E' direction of the COT 110 is connected to the 'E' direction of the first RN 120-1, and the 'W' direction of the COT 110 is connected to the 'E' direction of the second RN 120-2 (CASE 5). In this case, the COT 110 and the first RN 120-1 are connected via a first optical cable, the COT 110 and the second RN 120-2 are connected via a second optical cable, and the first RN 120-1 and the second RN 120-2 are connected via a third optical cable.

[0097] Since the second band filter 320 of the first RN 120-1 is connected in the 'E' direction of the first RN 120-1, no reflected signal is generated when the first WDM signal is input to the second band filter 320 of the first RN 120-1. In the case of the second wavelength filter 350-2 at the rear end of the second band filter 320, only the second optical signal is filtered, so the first or third optical signal of the first WDM signal is not filtered, and therefore no reflected signal is generated.

[0098] Meanwhile, since the first band-pass filter 310 of the first RN 120-1 is connected in the 'W' direction of the first RN 120-1, when a second WDM signal is input to the first band-pass filter 310 of the first RN 120-1, a second reflected signal is generated by the first wavelength filter 350-1 and first signal reflector 360-1 at the rear end of the first band-pass filter 310. This is because the first wavelength filter 350-1 can selectively filter the first or second optical signal. The generated second reflected signal is transmitted to the COT 110 via the third optical cable, the second RN 120-2, and the second optical cable.

[0099] As described with reference to FIG. 4, the third band filter 330 of the second RN 120-2 is connected in the 'W' direction of the second RN 120-2, and the fourth band filter 340 is connected in the 'E' direction of the second RN 120-2, thereby generating a third reflected signal and a fourth reflected signal and transmitting them to the COT 110.

[0100] Therefore, the controller 250 cannot receive only the first reflected signal among the first through fourth reflected signals, and determines that there is an error in the connection direction of the first RN 120-1 and that the second RN 120-2 is normally connected.

[0101] Referring to FIG. 9, an example is shown in which the 'E' direction of the COT 110 is connected to the 'W' direction of the second RN 120-2, and the 'W' direction of the COT 110 is connected to the 'W' direction of the first RN 120-2 (CASE 6).

[0102] 8, in this case, since only the connection order of the first RN 120-1 and the second RN 120-2 has been changed, the controller 250 cannot receive only the first reflected signal among the first through fourth reflected signals, and therefore determines that there is an error in the connection direction of the first RN 120-1 and that the second RN 120-2 is normally connected.

[0103] 10, a case is illustrated in which the 'E' direction of the COT 110 is connected to the 'W' direction of the first RN 120-1, and the 'W' direction of the COT 110 is connected to the 'W' direction of the second RN 120-2 (CASE 7). In this case, the COT 110 and the first RN 120-1 are connected via a first optical cable, and the COT 110 and the second RN 120-2 are connected via a second optical cable.

[0104] As described with reference to FIG. 4, the first band filter 310 of the first RN 120-1 is connected in the 'W' direction of the first RN 120-1, and the second band filter 320 is connected in the 'E' direction of the first RN 120-1, thereby generating a first reflected signal and a second reflected signal and transmitting them to the COT 11.

[0105] The third band pass filter 330 of the second RN 120-2 is connected in the 'E' direction of the second RN 120-2, so that no reflected signal is generated when the second WDM signal is input to the third band pass filter 330. The third wavelength filter 350-3 at the rear end of the third band pass filter 330 can filter only the third optical signal, so the second or fourth optical signal of the second WDM signal is not filtered, and therefore no reflected signal is generated.

[0106] Meanwhile, the fourth band filter 340 of the second RN 120-2 is connected in the 'W' direction of the second RN 120-2. When the first WDM signal is input to the fourth band filter 340, a third reflected signal is generated by the fourth wavelength filter 350-4 and fourth signal reflector 360-4 at the rear end of the fourth band filter 340. This is because the fourth wavelength filter 350-4 can selectively filter the third or fourth optical signal. The generated third reflected signal is transmitted to the COT 110 via the third optical cable, the first RN 120-1, and the first optical cable.

[0107] In this way, the controller 250 cannot receive only the fourth reflected signal among the first through fourth reflected signals, and therefore determines that the first RN 120-1 is normally connected and that only the second RN 120-2 has a connection direction error.

[0108] Referring to FIG. 11, an example is shown in which the 'E' direction of the COT 110 is connected to the 'E' direction of the second RN 120-2, and the 'W' direction of the COT 110 is connected to the 'E' direction of the first RN 120-1 (CASE 8).

[0109] 10, since only the connection order of the first RN 120-1 and the second RN 120-2 has been changed, the controller 250 cannot receive only the fourth reflected signal among the first through fourth reflected signals. Therefore, the controller 250 determines that the first RN 120-1 is connected normally, and that only the second RN 120-2 has a connection direction error.

[0110] Referring to FIG. 12, an example is shown in which the 'E' direction of the COT 110 is connected to the 'E' direction of the first RN 120-1, and the 'W' direction of the COT 110 is connected to the 'W' direction of the second RN 120-2 (CASE 9).

[0111] This example is a case where the connection directions of the first RN 120-1 and the second RN 120-2 are both reversed, as in the embodiment described with reference to Figures 8 and 10, so that the first reflected signal and the fourth reflected signal are not generated, and only the second reflected signal and the third reflected signal are generated.

[0112] Therefore, controller 250 determines that there is a connection direction error in both first RN 120-1 and second RN 120-2.

[0113] Referring to FIG. 13, an example is shown in which the 'E' direction of the COT 110 is connected to the 'E' direction of the second RN 120-2, and the 'W' direction of the COT 110 is connected to the 'W' direction of the first RN 120-2 (CASE 10).

[0114] 12, only the connection order of the first RN 120-1 and the second RN 120-2 has been changed, so in this example, the controller 250 can only receive the second and third reflected signals out of the first through fourth reflected signals, and therefore determines that there is a connection direction error in both the first RN 120-1 and the second RN 120-2.

[0115] A monitoring table (see FIG. 14) in which the results of the above-mentioned CASE1 to CASE10 are pre-collected is pre-stored in a storage space (not shown) provided in the controller 250, and the controller 250 compares the received reflected signal with the monitoring table to monitor the connection status of the RNs (120-1 to 120-n) connected to the COT 110.

[0116] Therefore, according to the present invention, the connection status between optical communication devices (ie, COT 110 and RNs 120-1 to 120-n) can be effectively monitored from a remote location without an on-site visit by an administrator.

[0117] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that the present invention can be modified and changed in various ways without departing from the spirit and scope of the present invention as defined in the following claims. [Explanation of symbols]

[0118] 100: Optical communication systems 110:COT(Central Office Terminal) 120:RN (Remote Node)

Claims

1. An optical communication device for an optical ring network, comprising: a first optical signal processing unit that outputs a first optical signal of a first wavelength; a first multiplexer / demultiplexer (MUX / DEMUX) that outputs the first optical signal in a first direction and receives and outputs a first reflected signal generated by the first optical signal being reflected by a first remote optical communication device to which the first optical signal is assigned; a second optical signal processing unit that outputs a second optical signal having a second wavelength; a second MUX / DEMUX that outputs the second optical signal in a second direction opposite to the first direction, and receives and outputs a second reflected signal generated by the second optical signal being reflected by a first remote optical communication device to which the second optical signal is assigned; and a controller that analyzes the connection status of a first remote optical communication device in the optical ring network, the first remote optical communication device to which the first and second optical signals are assigned, based on whether the first and second reflected signals are received.

2. the first remote optical communication device; 2. The optical communication device according to claim 1, configured to generate a corresponding reflected signal when the first or second optical signal is received in a predetermined direction of the first and second directions.

3. 3. The optical communication device of claim 2, wherein the controller determines that a connection error has occurred in the first remote optical communication device if only one of the first and second reflected signals is received.

4. a third optical signal processing unit that outputs a third optical signal having a third wavelength to the first MUX / DEMUX; a fourth optical signal processing unit that outputs a fourth optical signal having a fourth wavelength to the second MUX / DEMUX; the first MUX / DEMUX multiplexes the first optical signal and the third optical signal and outputs the multiplexed signal in the first direction, receives a third reflected signal generated by reflection by a second remote optical communication device to which the third optical signal is assigned, and outputs the third reflected signal to the controller; the second MUX / DEMUX multiplexes the second optical signal and the fourth optical signal and outputs the multiplexed signal in the second direction, receives a fourth reflected signal generated by reflection by a second remote optical communication device to which the fourth optical signal is assigned, and outputs the fourth reflected signal to the controller; 2. The optical communication device of claim 1, wherein the controller analyzes a connection status of a second remote optical communication device in the optical ring network to which the third and fourth optical signals are assigned based on whether the third and fourth reflected signals are received.

5. the second remote optical communication device; 5. The optical communication device according to claim 4, configured to generate a corresponding reflected signal when the third or fourth optical signal is received in a predetermined direction of the first or second directions.

6. 6. The optical communication device of claim 5, wherein the controller determines that a connection error has occurred in the second remote optical communication device if only one of the third and fourth reflected signals is received.

7. An optical communication device configured in an optical ring network, a first optical communication device that transmits a first optical signal at a first wavelength in a first direction and transmits a second optical signal at a second wavelength in a second direction opposite to the first direction; a second optical communication device that, when the first optical signal is received, reflects the first optical signal to generate a first reflected signal, and, when the second optical signal is received, reflects the second optical signal to generate a second reflected signal, and transmits the first and second reflected signals to the first optical communication device; The first optical communication device analyzes a connection state of the second optical communication device based on the first and second reflected signals.

8. 8. The optical communication system of claim 7, wherein the second optical communication device is configured to generate a corresponding reflected signal when the first or second optical signal is received in a predetermined direction of the first and second directions.

9. 9. The optical communication system of claim 8, wherein the first optical communication device determines that a connection error has occurred in the second optical communication device if only one of the first and second reflected signals is received.

10. the first optical communication device transmits a third optical signal having a third wavelength in the first direction and a fourth optical signal having a fourth wavelength in the second direction; The optical communication system further includes a third optical communication device that, when the third optical signal is received, reflects the third optical signal to generate a third reflected signal, and, when the fourth optical signal is received, reflects the fourth optical signal to generate a fourth reflected signal, and transmits the third and fourth reflected signals to the first optical communication device; The optical communication system of claim 7 , wherein the first optical communication device analyzes the connection status of the third optical communication device based on the third and fourth reflected signals.

11. 11. The optical communication system of claim 10, wherein the third optical communication device is configured to generate a corresponding reflected signal when the third or fourth optical signal is received in a predetermined direction of the first or second directions.

12. 12. The optical communication system of claim 11, wherein the first optical communication device determines that a connection error has occurred in the third optical communication device if only one of the third and fourth reflected signals is received.

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