KR101261961B1 - Passive optical network and the method of detecting ont - Google Patents

Abstract

According to the present invention, there is provided a PON system for detecting an ONT fault, comprising: a plurality of ONT terminals including at least one virtual ONT terminal for outputting an optical signal in a time slot interval allocated according to a time division access control scheme; Receiving an optical signal outputted from the plurality of ONT terminals, and determining an existence of an LOS signal corresponding to a trigger signal of a time slot section of the virtual ONT terminal to detect an abnormal state ONT; It is characterized by.
According to the present invention, a virtual terminal is formed in a plurality of ONT terminals connected to an optical line terminator, a trigger signal is applied to a virtual terminal section, and a corresponding LOS signal is detected to determine whether there is a failure ONT, thereby quickly By taking action, we can provide reliable services.

Description

PONIVE system and method for detecting ONT error thereof {PASSIVE OPTICAL NETWORK AND THE METHOD OF DETECTING ONT}

The present invention relates to a PON system and an ONT abnormality detection method. In particular, a virtual terminal is formed in a plurality of ONT terminals connected to an optical line terminator, and a trigger signal is applied to detect a corresponding LOS signal to detect the presence of a faulty ONT. The present invention relates to a PON system and an ONT abnormality detection method that can be determined.

Recently, as Internet users using wireless communication have rapidly increased, high-speed Internet technologies have been developed to provide faster Internet services to users.

The wireless LAN technology is a typical technology for such a high speed Internet service.

An optical communication system is a system for transmitting and receiving data based on an optical signal. An optical transmission line terminator of a station is a device for relaying data transmission between a server providing various data services to a subscriber through a telephone network or an internet network and optical network terminals connected to each subscriber terminal. The optical path terminator transmits the transmission data of the server to the target optical network terminal, and forms an optical signal for receiving the transmission data of the target optical network terminal.

In general, a passive optical network (PON) is an optical subscriber construction method that provides an optical fiber-based high-speed service to an enterprise or a home, and an optical fiber terminal device (ONT) at the bottom of the This is how you can connect. At this time, the TDM-PON using a time division multiplexing scheme distributes or distributes the downstream optical signal to the subscribers, and combines the upstream optical signals from the subscribers.

In the passive optical network using time division multiplexing, the data transmission / reception method between the optical line terminator and the optical network terminal is performed by inserting the identifier of the optical network terminal to which the optical line terminator is registered in the preamble of the frame. Sends only frames with their identifiers to the user interface. On the other hand, in the upstream, when the fiber terminator dynamically allocates an upstream time slot to all the fiber terminals, each fiber terminator transmits data to the fiber terminator during the time slot allocated to the tall.

However, although the optical terminals must perform upstream only during the assigned time slots, a failure occurs in one optical terminal and a continuous signal is transmitted, thereby causing an overall communication failure.

The technical problem to be solved by the present invention is to form a virtual terminal on a plurality of ONT terminals connected to the optical line termination device, and apply a trigger signal to detect the corresponding LOS signal to determine whether there is a failure ONT PON system and An ONT abnormality detection method is provided.

Technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to an aspect of the present invention, there is provided a PON system for detecting an ONT abnormality, comprising: a plurality of ONT terminals including at least one virtual ONT terminal for outputting an optical signal in a time slot interval allocated according to a time division access control scheme; With; Receiving an optical signal outputted from the plurality of ONT terminals, and determining an existence of an LOS signal corresponding to a trigger signal of a time slot section of the virtual ONT terminal to detect an abnormal state ONT; It is characterized by.

The optical line terminator includes: an MCU which assigns a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to the plurality of ONT terminals and a virtual ONT terminal; An optical receiver for receiving an optical signal from the ONT terminals and the virtual ONT terminal; An abnormal signal detection unit determining whether an LOS signal is present in a time slot section of the virtual ONT terminal; The abnormal signal detector includes a PON unit configured to apply a trigger signal to the time slot section of the virtual ONT, and determine whether an abnormal state ONT terminal is present according to whether the abnormal signal detector detects an LOS signal. .

The abnormal signal detector is characterized in that it is determined as a time slot section of the virtual ONT based on a trigger signal applied from the PON unit.

The PON unit may determine that there is an ONT terminal in an abnormal state when the LOS signal is detected by the abnormal signal detector, and determine that the ONT terminals are in a normal state when the LOS signal is not detected.

Here, the photoelectric conversion unit for converting the optical signal received from the light receiving unit into an electrical signal; An optical power detector for converting a signal converted into an electrical signal by the photoelectric converter into a digital signal and detecting optical power of an ONT terminal and a virtual ONT terminal in response to a trigger signal applied from the PON unit; It is characterized in that it further comprises a database unit for storing the optical power level data for the ONT terminal and the virtual ONT terminal detected by the optical power detector.

Here, the PON unit is characterized in that it is determined that there is an ONT terminal in an abnormal state when the size of the optical power level of the virtual ONT terminal detected by the optical power detector is greater than or equal to a predetermined value.

The method may include assigning a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to a plurality of ONT terminals and a virtual ONT terminal; Setting a time slot to output an optical signal to each ONT terminal and a virtual ONT terminal according to a time division access control scheme; Applying a trigger signal to a time slot period of the virtual ONT terminal; Receiving an optical signal from the ONT terminal and the virtual ONT terminal and detecting the presence or absence of an LOS signal in a section to which the trigger signal is applied; When the LOS signal is detected, it is characterized in that it comprises the step of determining the abnormal state for the ONT terminals.

Converting the received optical signal into an electrical signal; Converting the converted electrical signal into a digital signal and detecting an optical power level of an ONT terminal and a virtual ONT terminal in response to an applied trigger signal; Storing optical power level data of the detected ONT terminal and a virtual ONT terminal; The method may further include determining that there is an ONT terminal in an abnormal state when the detected optical power level of the virtual ONT terminal is greater than or equal to a predetermined value.

The method may further include detecting LOS signals of the ONT terminal and the virtual ONT terminal in response to the applied trigger signal.

According to the present invention, a virtual terminal is formed in a plurality of ONT terminals connected to an optical line terminator, a trigger signal is applied to a virtual terminal section, and a corresponding LOS signal is detected to determine whether there is a failure ONT, thereby quickly By taking action, we can provide reliable services.

1 is a diagram schematically showing the configuration of a PON system of the present invention.
2 is a view schematically showing the configuration of an optical line terminator according to a first embodiment of the present invention;
3 is a diagram illustrating an output of an LOS signal corresponding to a trigger signal according to a first embodiment of the present invention.
4 is a flowchart illustrating a fault detection method of the PON system according to the first embodiment of the present invention.
5 is a view schematically showing the configuration of an optical line terminator according to a second embodiment of the present invention;
6 is a diagram illustrating an LOS signal and an optical power level according to a trigger signal of an ONT terminal section and a virtual terminal section according to a second embodiment of the present invention.
7 is a flowchart illustrating a method for detecting ONT anomaly in a PON system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The same reference numerals are used for portions having similar functions and functions throughout the drawings.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . Also, to include an element does not exclude other elements unless specifically stated otherwise, but may also include other elements.

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

1 is a view schematically showing the configuration of a PON system of the present invention. As shown in FIG. 1, the PON system 100 includes a plurality of ONT terminals 130 including at least one virtual ONT terminal for outputting an optical signal in a time slot interval allocated according to a time division access control scheme. And an optical line terminator for receiving an optical signal output from the plurality of ONT terminals 130 and detecting an abnormal state ONT by determining whether an LOS signal corresponding to a trigger signal of a time slot section of the virtual ONT terminal is present. (OLT) 110.

The plurality of ONT terminals and the virtual ONT terminals are sequentially arranged. In this case, the virtual ONT terminal may be formed every Nth time that the ONT terminals are sequentially arranged. That is, # 1 ONT, # 2 ONT, # 3 ONT, # V1 ONT, # 5 ONT, # 6 ONT, # 7 ONT, # V2 ONT, # 9 ONT, # 10 ONT, # 11 ONT, # V3 ONT. ... may be arranged sequentially. Therefore, # 1 ONT, # 2 ONT, # 3 ONT, and # V1 ONT may be divided into one grouping. For example, if 64 ONTs can be connected to one PON device, they can be divided into 16 groups with virtual ONTs corresponding to them. At this time, the order in which the virtual ONTs are arranged can be changed as necessary. Each of the ONT terminals is provided with an optical transmission / reception module to up / down stream the optical line termination device and the optical signal.

The optical line terminator 110 includes at least one PON module, and each PON module uses a splitter 120 in an optical cable to connect with the ONT terminals 130. 130 can be connected.

In general, since the optical line terminator 110 performs a communication function, it performs a bidirectional optical transmission function. For example, in the E-PON network, since a bi-directional communication is performed using a single optical fiber, data communication is performed by applying optical signals having two different wavelengths (1490 nm / 1310 nm). In such an E-PON network, Internet data communication is performed by applying 1490 nm as a downstream optical signal (output part of the transmitter) and 1310 nm as an upstream optical signal (transmitter).

2 is a view schematically showing the configuration of the optical line terminator according to the first embodiment of the present invention. As shown in FIG. 2, the optical line terminator 110 includes an optical receiver 210, an abnormal signal detector 220, a PON unit 230, and an MCU 240.

The MCU 240 allocates a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to a plurality of ONT terminals and a virtual ONT terminal. At this time, an assigned Logical Link ID (LLID) establishes a logical link between one ONT and an optical line terminator, which applies a specific Service Level Agreement (SLA) agreement.

Then, time slots are allocated to the ONT terminal 130 and the virtual ONT terminals # 1 ONT, # 2 ONT, # 3 ONT, and # V1 ONT, respectively.

The optical receiver 210 receives an optical signal from the ONT terminals and the virtual ONT terminal. Here, the light receiving unit 210 is preferably composed of a photo diode. In addition, the ONT terminals 130 may further include an optical transmitter (not shown) for upstreaming an optical signal, and the optical receiver 210 and the transmitter may be implemented as one optical transceiver module. .

The abnormal signal detector 220 receives an LOS signal, which is an optical signal of the ONT terminals 130, received from the optical receiver 210. Here, the LOS signal indicates the output state of the optical signal over time. In this case, since the abnormal signal detection unit 220 does not distinguish which ONT terminal the LOS signal is input from, it is distinguished from the ONT terminal by receiving a trigger signal applied from the PON unit 230. Therefore, the trigger signal is applied to the time slot section of the virtual ONT terminal, and it is determined whether the LOS signal is present in the corresponding section. In other words, it is determined as a time slot section of the virtual ONT by the trigger signal applied from the PON unit, and the LOS signal is detected.

The PON unit 230 applies a trigger signal to the abnormal signal detector 220 in the time slot section of the virtual ONT, and according to whether the abnormal signal detector 220 detects the LOS signal, whether the abnormal state ONT terminal is present or not. Judge. That is, when the LOS signal is not detected in the time slot section of the virtual ONT, the ONT terminals determine the normal state, and when the LOS signal is detected, it is determined that the abnormal ONT exists.

3 is a diagram illustrating an output of an LOS signal corresponding to a trigger signal according to the first embodiment of the present invention. As shown in FIG. 3, when a trigger signal is applied to the time slot section of the virtual ONT, and if no LOS signal is detected in the time slot section of the virtual ONT, the ONT terminals determine that the normal state and the LOS signal is detected. If ONT is determined to exist.

4 is a flowchart illustrating a method for detecting an abnormality of a PON system according to a first embodiment of the present invention. As shown in FIG. 4, in the abnormality detecting method of the PON system, first, a unique Logical Link ID (LLID) is allocated to each ONT terminal and a virtual ONT terminal from an optical line terminator (OLT) (S401). .

The ONT terminals 130 are each assigned a unique Logical Link ID (LLID) from the optical line terminator. At this time, the # V1 ONT is virtually assigned a virtual LLID.

In more detail, the virtual ONT terminal may be formed every Nth times the ONT terminals are sequentially arranged. For example, # 1 ONT, # 2 ONT, # 3 ONT, # V1 ONT, # 5 ONT, # 6 ONT, # 7 ONT, # V2 ONT, # 9 ONT, # 10 ONT, # 11 ONT, # V3 ONT ... etc. can be assigned sequentially. As such, when the V-LLIDs of the virtual terminals are allocated to each other, # 1 ONT, # 2 ONT, # 3 ONT, and # V1 ONT may be divided into one grouping. For example, if you can connect # 64 ONTs to one PON device, it can be divided into 16 groups with virtual ONTs corresponding to them. At this time, the order in which the virtual ONTs are arranged can be changed as necessary.

In operation S402, a time slot is set to output an optical signal to each ONT terminal and a virtual ONT terminal according to a time division access control scheme. Here, time slots are allocated to each ONT terminal and a virtual ONT terminal in correspondence with each time schedule.

Subsequently, a trigger signal is applied to a time slot section of the virtual ONT terminal (S403). More specifically, the PON unit informs the time slot for receiving the optical signal of the virtual ONT terminal by applying a trigger signal to the abnormal signal detection unit.

Thereafter, an optical signal of a time slot interval allocated to the virtual ONT terminal to which the trigger signal is applied is received to detect the presence or absence of an LOS signal (S404). That is, an optical signal is received in correspondence with each time slot allocated to the ONT terminal and the virtual ONT. In this case, when an optical signal is received from the virtual ONT terminal, which is a section in which the trigger signal is applied, the abnormal signal detection unit generates an LOS signal. In other words, when the LOS signal for the virtual ONT terminal is detected (S405), it is determined that there is a terminal in an abnormal state (S406).

FIG. 5 is a diagram schematically illustrating a configuration of an optical line terminator according to a second embodiment of the present invention. As shown in FIG. 5, the optical line terminator 110 includes an optical module 510 including an optical receiver 511, a photoelectric converter 512, an optical power detector 513, and a database 514. ), The abnormal signal detector 520, the PON unit 530, and the MCU 540.

The MCU 540 assigns a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to a plurality of ONT terminals and a virtual ONT terminal. At this time, an assigned Logical Link ID (LLID) establishes a logical link between one ONT and an optical line terminator, which applies a specific Service Level Agreement (SLA) agreement.

Then, time slots are allocated to the ONT terminal 130 and the virtual ONT terminals # 1 ONT, # 2 ONT, # 3 ONT, and # V1 ONT, respectively.

The optical receiver 511 receives optical signals from the ONT terminals and the virtual ONT terminal. Here, the light receiving unit 511 is preferably composed of a photo diode. In addition, the ONT terminals 130 may further include an optical transmitter (not shown) for upstreaming an optical signal, and the optical receiver 201 and the transmitter may be implemented as one optical transceiver module. .

The photoelectric converter 512 converts the optical signal received by the optical receiver 511 into an electrical signal.

The optical power detector 513 converts a signal converted into an electrical signal by the photoelectric converter 512 into a digital signal, and in response to a trigger signal applied by the PON unit 530, the optical power detector 513 of the ONT terminal and the virtual ONT terminal. Detect the optical power level.

The database 514 stores optical power level data of the ONT terminals 130 detected by the optical power detector 513. That is, data such as unique Logical Link ID (LLID), optical power output value, product information, and temperature for each ONT terminal are stored.

The abnormal signal detector 520 receives an LOS signal which is an optical signal of the ONT terminals received from the optical receiver 511. Here, the LOS signal indicates the output state of the optical signal over time. In this case, since the abnormal signal detection unit 520 does not distinguish which ONT terminal the LOS signal is input from, which signal is output from the ONT terminal, the abnormal signal detection unit 520 receives the trigger signal applied from the PON unit 530 to distinguish the ONT terminal. Therefore, the trigger signal is applied to the time slot section of the virtual ONT terminal, and it is determined whether the LOS signal is present in the corresponding section. In other words, the trigger signal applied from the PON unit 530 determines the time slot period of the virtual ONT, and detects the LOS signal.

The PON unit 530 applies a trigger signal to the abnormal signal detection unit 520 in the time slot section of the virtual ONT, and whether or not the abnormal state ONT terminal is present according to whether the abnormal signal detection unit 520 detects the LOS signal. Judge. That is, when the LOS signal is not detected in the time slot section of the virtual ONT, the ONT terminals determine the normal state, and when the LOS signal is detected, it is determined that the abnormal ONT exists.

In addition, the PON unit 530 receives the optical power level data for the ONT terminals 130 by applying a trigger signal corresponding to each time slot of the ONT terminals 130 to the photoelectric conversion unit. Status ONT Determines whether there is a terminal.

In more detail, the PON unit 530 determines whether there is an ONT terminal in an abnormal state according to whether an optical signal is detected from a time slot section allocated to the virtual ONT terminal, and is allocated to the virtual ONT terminal V1. If the optical power size of the optical signal is greater than or equal to a predetermined value in the time slot period, it is determined that there is an ONT terminal in an abnormal state.

That is, the PON unit 530 determines whether there is an abnormal state ONT according to the optical power level value while determining whether the abnormal state ONT is detected by the detection of the LOS signal from the abnormal signal detection unit 520 in the virtual terminal section. You will be judged. Therefore, the judgment as to whether or not the abnormal state ONT can be made more accurate.

6 is a diagram illustrating an LOS signal and an optical power level according to trigger signals of an ONT terminal section and a virtual terminal section according to a second embodiment of the present invention. As shown in FIG. 6, the PON unit 530 applies a trigger signal to the photoelectric conversion unit 512 and the abnormal signal detection unit 520. In this case, the time point at which the trigger signal is applied is applied corresponding to the time slot of each ONT terminal. Therefore, when the optical signal is received when the trigger signal is applied, the LOS signal is output. Here, when the LOS signal is output in accordance with the trigger signal applied to the time slot period of the virtual ONT terminal, the abnormal terminal exists.

In addition, the optical power level of the optical signal of the time slot of the ONT terminals 130 and the time slot of the virtual ONT terminal is detected to determine whether there is an abnormal state ONT terminal. That is, when the optical power magnitude of the optical signal is greater than or equal to a predetermined value in the time slot period allocated to the virtual ONT terminal V1, it may be determined that the output of the optical signal by the ONT terminal in an abnormal state continues.

Therefore, when the LOS signal is detected in the time slot period of the virtual ONT terminal or the optical power level of the optical signal is more than a predetermined value, it is determined that an abnormal state ONT terminal exists.

7 is a flowchart illustrating a method for detecting ONT abnormality of the PON system according to the present invention. As shown in FIG. 7, in the method for detecting ONT anomaly of the PON system according to the present invention, first, a unique Logical Link ID (LLID) is assigned to each ONT terminal and a virtual ONT terminal from an optical line terminator (step 1). S701).

The ONT terminals 130 are each assigned a unique Logical Link ID (LLID) from the optical line terminator. At this time, the # V1 ONT is virtually assigned a virtual LLID.

In more detail, the virtual ONT terminal may be formed every Nth times the ONT terminals are sequentially arranged. For example, # 1 ONT, # 2 ONT, # 3 ONT, # V1 ONT, # 5 ONT, # 6 ONT, # 7 ONT, # V2 ONT, # 9 ONT, # 10 ONT, # 11 ONT, # V3 ONT ... etc. can be assigned sequentially. As such, when the V-LLIDs of the virtual terminals are allocated to each other, # 1 ONT, # 2 ONT, # 3 ONT, and # V1 ONT may be divided into one grouping. For example, if you can connect # 64 ONTs to one PON device, it can be divided into 16 groups with virtual ONTs corresponding to them. At this time, the order in which the virtual ONTs are arranged can be changed as necessary.

In operation S702, a time slot is set to output an optical signal to each ONT terminal and a virtual ONT terminal according to a time division access control scheme.

Here, time slots are allocated to each ONT terminal and a virtual ONT terminal in correspondence with each time schedule.

Next, a step of applying a trigger signal to a time slot period allocated to each of the ONT terminal and the virtual ONT terminal is performed (S703). More specifically, the PON unit informs the time slot for receiving the optical signal of the virtual ONT terminal by applying a trigger signal to the abnormal signal detection unit.

Thereafter, an optical signal of a time slot period allocated to the virtual ONT terminal to which the trigger signal is applied is received to detect the presence or absence of an LOS signal (S704). That is, an optical signal is received in correspondence with each time slot allocated to the ONT terminal and the virtual ONT. In this case, when an optical signal is received from the virtual ONT terminal, which is a section in which the trigger signal is applied, the abnormal signal detection unit generates an LOS signal.

In other words, when the LOS signal for the virtual ONT terminal is detected (S705), it is determined that there is a terminal in an abnormal state (S707).

Subsequently, when the optical power value of the optical signal detected in the virtual ONT terminal section is greater than or equal to a predetermined size (S706), an abnormal state of the ONT terminals is determined (S707).

More specifically, converts the received optical signal into an electrical signal, converts the converted electrical signal into a digital signal, and detects optical power levels of the ONT terminal and the virtual ONT terminal in response to an applied trigger signal, The optical power level data of the detected ONT terminal and the virtual ONT terminal are stored.

Here, the presence or absence of the abnormal state ONT terminal is determined by comparing the optical power data of the detected optical signal with the optical power data of the database unit. The optical power values for the optical signals of the respective ONT terminals may have a predetermined difference, and these are previously compared with the database values. In addition, it is determined whether an optical signal is detected in a time slot allocated to the virtual ONT terminal.

Specifically, it is determined whether there is an ONT terminal in an abnormal state according to whether the optical signal of the time slot section allocated to the virtual ONT terminal is detected, and the optical power size of the optical signal is predetermined in the time slot section allocated to the virtual ONT terminal. If the value is over, it is determined that there is an ONT terminal in an abnormal state. For example, if any one of # 1 ONT, # 2 ONT, or # 3 ONT fails and the output of the optical signal continues, the optical signal is monopolized in the time slot section assigned to the virtual ONT terminal because the optical line is monopolized. Is detected. That is, the ONT terminals determine that the normal state should be no light detection in the time slot period allocated to the virtual ONT terminal.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of course, this is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the equivalents as well as the claims that follow.

Description of the Related Art
110 --- Optical line terminator 210 --- Optical receiver
510 --- Optical module 220, 520 --- Abnormal signal detection unit 230, 530 --- PON unit 240, 540 --- MCU

Claims (9)

A plurality of ONT terminals including at least one virtual ONT terminal for outputting an optical signal in an allocated time slot interval according to a time division access control scheme;
Receiving an optical signal output from the plurality of ONT terminals, and determining an existence of an LOS signal corresponding to a trigger signal of a time slot section of the virtual ONT terminal to detect an abnormal state ONT;
The optical line terminator includes: an MCU which assigns a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to the plurality of ONT terminals and a virtual ONT terminal; An optical receiver for receiving an optical signal from the ONT terminals and the virtual ONT terminal; An abnormal signal detection unit determining whether an LOS signal is present in a time slot section of the virtual ONT terminal; And a PON unit configured to apply a trigger signal to the time slot section of the virtual ONT to the abnormal signal detector, and determine whether an abnormal state ONT terminal is present or not according to whether the LOS signal is detected by the abnormal signal detector. .
delete The method of claim 1,
The abnormal signal detection unit is a PON system, characterized in that for determining the time slot interval of the virtual ONT by the trigger signal applied from the PON unit.
The method of claim 1,
The PON unit determines that there is an ONT terminal in an abnormal state when the LOS signal is detected by the abnormal signal detector, and determines the ONT terminals as a normal state when the LOS signal is not detected.
The method of claim 1,
And the PON unit determines that there is an ONT terminal in an abnormal state when the size of the optical power level of the virtual ONT terminal detected by the optical power detector is greater than or equal to a predetermined value.
The method of claim 1,
A photoelectric converter converting the optical signal received from the optical receiver into an electrical signal;
An optical power detector for converting a signal converted into an electrical signal by the photoelectric converter into a digital signal and detecting optical power of an ONT terminal and a virtual ONT terminal in response to a trigger signal applied from the PON unit;
And a database unit for storing optical power level data for the ONT terminal and the virtual ONT terminal detected by the optical power detector.
Allocating a unique Logical Link ID (LLID) and a Virtual Logical Link ID (V-LLID) to the plurality of ONT terminals and the virtual ONT terminal;
Setting a time slot to output an optical signal to each ONT terminal and a virtual ONT terminal according to a time division access control scheme;
Applying a trigger signal to a time slot period of the virtual ONT terminal;
Receiving an optical signal from the ONT terminal and the virtual ONT terminal and detecting the presence or absence of an LOS signal in a section to which the trigger signal is applied;
Determining the abnormal state of the ONT terminals when the LOS signal is detected;
Converting the received optical signal into an electrical signal; Converting the converted electrical signal into a digital signal and detecting an optical power level of an ONT terminal and a virtual ONT terminal in response to an applied trigger signal; Storing optical power level data of the detected ONT terminal and a virtual ONT terminal; And determining that there is an ONT terminal in an abnormal state when the detected optical power level of the virtual ONT terminal is greater than or equal to a predetermined value.
delete 8. The method of claim 7,
And detecting LOS signals of the ONT terminal and the virtual ONT terminal in response to the applied trigger signal.

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