KR20090058388A - The optical network unit with malfunction detecting ability in a tdm passive optical network and the malfuncion detecting method - Google Patents

Abstract

An optical network termination device with a malfunction detecting function a TDM(Time Division Multiplex) passive optical network and a malfunction detecting method are provided to convert an optical signal transmitted from a laser diode of an ONU into a digital signal, generate trigger signals of different types and compare the trigger signal with the digital signal, thereby determining whether malfunction occurs. A laser diode(211) modulates laser into an optical signal and transmits it to an OLT(Optical Line Terminal). A laser driving device(220) supplies an oscillation current for oscillating the laser and a modulation current for modulating the oscillated laser into an optical signal. An optical detector(212) detects a part of an optical signal outputted from the laser diode and converts It into an electric signal. A processor(240) generates trigger signals of different types when the optical signal is transmitted to the OLT or not.

Description

TEM OPTICAL NETWORK UNIT WITH MALFUNCTION DETECTING ABILITY IN A TDM PASSIVE OPTICAL NETWORK AND THE MALFUNCION DETECTING METHOD}

The present invention compares the operation of the laser diode inside the optical network unit (Optical Network Unit) and the optical network termination device having a function of detecting a malfunction by comparing the optical signal transmission in the TDM passive optical network (Time Division Multiplex Passive Optical Network) Related to the detection method. More specifically, it detects a malfunction of the optical fiber terminator and cuts off the optical signal transmitted from the optical fiber terminator or cuts off the current supplied to the optical transmitter of the optical fiber terminator to prevent the optical transmitter from operating. An apparatus and method are disclosed.

With the rapid increase in Internet traffic and the convergence of broadcasting and telecommunication services, the speed of subscriber networks has been increasing rapidly. Among these technologies, passive optical network technology is not only able to provide high bandwidth to subscribers, but also due to the advantage that OSP (Outside Plant) is composed of only passive components, which greatly reduces the operating cost of the network. have. Passive optical networks can be broadly divided into i) time division multiplexing based TDM passive optical networks and ii) wavelength division multiplexing based WDM passive optical networks.

Among them, the TDM passive optical network refers to a method of multiplexing one circuit into a plurality of channels by dividing and transmitting a plurality of optical signals into a predetermined time interval, respectively. Compared to the frequency division multiplexing method of the analog method of dividing one line into narrow frequency bands and multiplexing, the multiplexing method divides one line into 100% digital high-speed multiple channels.

1 shows the structure of a typical TDM passive optical network 100. The TDM passive optical network 100 is a structure in which a plurality of subscribers share an optical fiber with one optical line terminal using a time division scheme, and currently, B-PON and G- standardized in ITU-T. PON, and E-PON standardized by IEEE etc. are used.

Referring to Figure 1, looks at the structure of a typical TDM passive optical network 100 in more detail. In view of the downlink signal, the optical line terminal device 110 of the service provider is provided with one optical transceiver to transmit the optical signal to each subscriber. The optical signal is transmitted to the optical splitter 130 through the trunk optical cable 120. The optical splitter 130 splits the power of the optical signal into 1 × N. Accordingly, the optical splitter 130 distributes one optical signal to the N subscriber lines 140. Finally, the optical signal branched by the optical splitter 130 is delivered to each of the optical network termination devices 200 on the N subscriber side to provide a communication service.

On the other hand, in view of the upstream signal, one optical transceiver is installed in each of the N optical network termination device 200 transmits an optical signal to the optical line terminal device (110). In this case, if two or more uplink optical signals are simultaneously transmitted in the N optical network termination devices 200, collisions between the optical signals occur. Accordingly, the TDM passive optical network 100 prevents collision of optical signals through time division multiplexing. That is, a predetermined time is divided into N time intervals, and each optical network termination apparatus 200 can transmit an uplink optical signal only during each time interval. Accordingly, the N optical network termination devices 200 may communicate with one optical line terminal device 110.

In order to achieve smooth communication in such a TDM passive optical network, when one optical fiber terminator is transmitting an uplink optical signal, the other optical fiber terminator must be turned off. This is because a collision of optical signals occurs when one optical network terminator transmits an optical signal while one optical network terminator transmits an uplink optical signal. Therefore, in a TDM passive optical network, it is very important that the optical signal is transmitted at the correct time at the optical transmitter of the optical fiber termination device.

However, in the conventional TDM optical network, when the optical transmitter of the optical network termination device malfunctions and transmits an optical signal even when it is not a predetermined time, the optical network termination device cannot determine whether the optical network terminal malfunctions. In addition, it is not possible to determine which optical network termination device is incorrectly transmitted from among the optical network termination devices connected to one optical line terminal device. Therefore, if the optical transmitter of some optical fiber termination devices malfunctions, i) a collision of optical signals may occur, and thus the entire TDM passive optical network may not operate. Therefore, there is a problem in that it is impossible to know whether a fiber termination device is malfunctioning, or iii) there is a problem in that all the fiber termination devices have to be inspected individually because it is not known which fiber termination device is malfunctioning.

The present invention discloses an apparatus and method for detecting a malfunction of an optical network termination device in a TDM passive optical network to solve the above problem. Specifically, the optical signal transmitted from the laser diode of the optical fiber termination device is converted into a digital signal, and different types of trigger signals are generated according to whether or not the optical signal should be transmitted from the laser diode to generate the digital signal and the trigger signal. Disclosed are an apparatus and a method for determining malfunction by comparing with each other.

The present invention provides an optical network termination device having a malfunction detection function in a TDM passive optical network, comprising: a laser diode for modulating a laser into an optical signal and transmitting the optical signal to an optical line terminal device; A laser driving device for supplying an oscillation current for oscillating the laser and a modulation current for modulating the oscillated laser into the optical signal; A photo detector which detects a part of the optical signal output from the laser diode and converts the optical signal into an electrical signal; And a processor configured to generate a trigger signal of a different type when the laser diode is operated to transmit the optical signal to the optical line terminal device and when not to transmit the optical signal.

Additionally, the present invention provides a method for detecting a malfunction of an optical fiber termination device in a TDM passive optical network, comprising: a first step of modulating a laser into an optical signal in a laser diode and transmitting the optical signal to an optical line terminal device; A second step of the optical detector detecting a portion of the optical signal and converting the detected optical signal into an electrical signal; And a third step of the processor generating a different type of trigger signal when the laser diode should transmit the optical signal to the optical line terminal device or not.

In the TDM passive optical network of the present invention, an apparatus and method for detecting malfunction of an optical fiber termination device have an advantage of detecting malfunction in each of a plurality of optical network termination devices connected to one optical line terminal device.

In addition, when a malfunction occurs in some of the optical fiber termination devices, the blocking device is activated to block the upstream transmission of the optical signal, so that the other optical fiber termination devices can operate normally. Therefore, the entire TDM passive optical network has the advantage that communication can be maintained stably because some optical network termination devices can always operate normally even if they malfunction.

In addition, the service provider can automatically identify the malfunctioning optical fiber termination device, which can save the cost and time required to manually inspect which optical fiber termination device is malfunctioning.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2A shows the structure of a fiber termination device 200 with a malfunction detection function in a TDM passive optical network. Referring to FIG. 2A, the laser diode 211 oscillates a laser and modulates the oscillated laser into an optical signal. In order to oscillate the laser in the laser diode 211 and modulate the laser into an optical signal, an oscillation current and a modulation current are required. The laser driving device 220 supplies the oscillation current and the modulation current to the laser diode 211. That is, since the laser driving device 220 supplies the oscillation current and the modulation current to the laser diode 211, the laser diode 211 oscillates the laser, modulates the oscillated laser into an optical signal, and transmits the light to the optical line terminal device. Send a signal.

When transmitting the optical signal from the laser diode 211 to the optical line terminal device 110, the optical detector 212 detects a part of the optical signal. At this time, the photo detector 212 detects only the generation of the optical signal. That is, what the user wants to know through the photo detector 212 is whether the laser diode 211 is operating. Finally, the photo detector 212 converts the detected optical signal into an electrical signal.

Since the converted electrical signal is an analog signal, the A / D converter 230 serves to convert it into a digital signal. A predetermined reference value is input to the A / D converter 230. The reference value refers to the size of an analog signal that can be considered that the laser diode 211 operates. The A / D converter 230 converts the analog signal into a digital signal of "0" or "1" depending on whether the magnitude of the analog signal exceeds a reference value. For example, i) if the size of the analog signal is larger than the reference value is converted to "1", ii) if the size of the analog signal is smaller than the reference value is converted to "0". At this time, it does not matter even if it is digitized to a value other than "0" or "1", it is only necessary that the two digital signals can be distinguished.

The processor 240 allows the N laser diodes 211 to operate without collision of the optical signal through periodic signal exchange with the optical network termination device 200. That is, when the processor 240 in each of the N optical fiber terminators 200 transmits an optical signal from the specific optical fiber terminator 200 to the optical line terminal device 110, the other optical network terminators 200 are optical signals. It prevents collision of the optical signal by controlling not to transmit it.

The processor 240 controls the operation of the laser diode 211 and the laser driver 220 to control the transmission of the optical signal. For example, if the processor 240 operates the laser diode 211 and the laser driving device 220 in a specific optical network termination device 200 to transmit an optical signal to the optical line terminal device 110, the other optical network termination device may be used. In the devices 200, the laser driving device 220 is stopped to prevent the oscillation current and the modulation current from being supplied to the laser diode 211, thereby preventing the optical signal from being transmitted to the optical line terminal device 110. Alternatively, the operation of the laser diode 211 itself is stopped so that the laser does not oscillate or the optical signal is not modulated.

In addition, the processor 240 generates a different type of trigger signal depending on whether the laser diode 211 is operated to transmit an optical signal to the optical line terminal device 110. For example, the processor 240 i) triggers the laser diode 211 to generate an A-type trigger signal when the optical signal needs to be transmitted to the optical line terminal device 110, and ii) the laser diode 211. By interrupting the operation of the optical signal to the optical line terminal device 110 when not to generate a B-type trigger signal.

The determination device 250 compares the digital signal output from the A / D converter 230 and the trigger signal of different types output from the processor 240. For example, it is assumed that the digital signal "1" is output when the laser diode 211 is operated to transmit an optical signal, and the digital signal "0" is output when the optical signal is not transmitted because the laser diode 211 is not operated. do. Meanwhile, the processor 240 outputs a trigger signal of type A when the optical signal is to be transmitted from the laser diode 211 to the optical line terminal device 110, and trigger signal of the type B when the optical signal should not be transmitted. Assume that is output. The following table lists the four possible cases.

TABLE 1

 Digital signal "1" (laser diode 211 is activated to transmit an optical signal)  Digital signal "0" (laser diode 211 is inoperative and no optical signal is transmitted)  A type trigger signal (light signal should be transmitted)  in normal operation  malfunction  B-shape trigger signal (should not transmit light signal)  malfunction  in normal operation

Referring to Table 1, when the input signal is the digital signal "1" and the A-type trigger signal, when the optical signal is to be transmitted, the laser diode 211 is operated to transmit the optical signal. 250 determines that the optical fiber termination device 200 is operating normally. However, when the input signal is the digital signal "0" and the A-type trigger signal, even when the optical signal is to be transmitted, since the laser diode 211 is not activated and the optical signal is not transmitted, the determination device 250 ) Determines that the optical fiber termination device 200 is malfunctioning. Accordingly, the determination device 250 may easily determine whether the optical network termination device 200 is malfunctioning by comparing whether the optical signal should be transmitted with the actual optical signal transmission according to the operation of the laser diode 211. . Therefore, since the service provider can accurately know the malfunctioning optical fiber termination device 200, it is possible to save the cost and time required to examine which optical fiber termination device 200 malfunctions.

2B and 2C illustrate the structure of the optical network termination apparatus 200 in which a blocking function is added to a malfunction detection function in a TDM passive optical network. The optical network termination device 200 not only determines whether the malfunction is described above, but also prevents optical signals from being transmitted from the malfunctioning optical network terminal device 200 to the optical line terminal device 110 so that the entire TDM passive optical network operates stably. To be possible.

Referring to FIG. 2B, a blocking device 260 is mounted between the laser driving device 220 and the laser diode 211. The blocking device 260 is controlled by the processor 240. When the optical network termination device 200 is determined to be malfunctioning by the determination device 250, the processor 240 operates the blocking device 260. Specifically, the blocking device 260 serves to block the oscillation current or the modulation current supplied from the laser driving device 220 to the laser diode 211. Therefore, since the laser diode 211 is not operated, the optical signal is not transmitted to the optical line terminal device 110, and the remaining optical network termination devices 200 may operate normally. Therefore, the entire TDM passive optical network can always operate normally even if some optical network termination device 200 malfunctions, so communication is maintained stably.

Referring to FIG. 2C, the blocking device 270 is mounted on a line in the upward direction of the laser diode 211, that is, in the direction of the optical line terminal device 110. The blocking device 270 is controlled by the processor 240. When the optical network termination device 200 is determined to be malfunctioning by the determination device 250, the processor 240 operates the blocking device 270. In detail, the blocking device 270 blocks the optical signal transmitted from the laser diode 211 to the optical line terminal device 110. Therefore, the optical signal is not transmitted to the optical line terminal device 110, the remaining optical network termination device 200 can operate normally. Therefore, the entire TDM passive optical network can always operate normally even if some optical network termination device 200 malfunctions, so communication is maintained stably.

1 shows the structure of a typical TDM passive optical network.

Figure 2a shows the structure of a fiber termination device with malfunction detection in a TDM passive optical network.

FIG. 2B illustrates the structure of an optical fiber termination device in which a blocking function is added to a malfunction detection function in a TDM passive optical network.

FIG. 2C shows another structure of the optical fiber termination device in which a blocking function is added to a malfunction detection function in a TDM passive optical network.

Claims (10)

Optical Network Unit with malfunction detection in TDM Time Division Multiplex Passive Optical Network, A laser diode that modulates the laser into an optical signal and transmits the laser to an optical line terminal; A laser driving device for supplying an oscillation current for oscillating the laser and a modulation current for modulating the oscillated laser into the optical signal; A photo detector which detects a part of the optical signal output from the laser diode and converts the optical signal into an electrical signal; And And a processor configured to generate a trigger signal of a different type when the laser diode is operated to transmit the optical signal to the optical line terminal device and to not transmit the optical signal. The method according to claim 1, And an A / D converter for converting an electrical signal output from the photo detector into a digital signal. The method according to claim 2, And a determination device that determines whether there is a malfunction by comparing different types of trigger signals output from the processor and digital signals output from the A / D converter. The method according to claim 3, And a blocking device to block the oscillation current and the modulation current supplied from the laser driving device to the laser diode when it is determined that the determination device is malfunctioning. The method according to claim 3, And a blocking device to block the optical signal transmitted from the laser diode to the optical line terminal device when it is determined that the determination device is malfunctioning. A method of detecting a malfunction of a fiber termination device in a TDM passive optical network, A first step of modulating a laser into an optical signal in a laser diode and transmitting the laser signal to an optical line terminal device; A second step of a photo detector detecting a portion of the optical signal and converting the detected optical signal into an electrical signal; And a third step of the processor generating different types of trigger signals when the laser diode should transmit the optical signal to the optical line terminal device and when it should not. The method according to claim 6, And a fourth step of the A / D converter converting the electrical signal output from the photo detector into a digital signal. The method according to claim 7, And a fifth step of determining, by the determination device, whether there is a malfunction by comparing different types of trigger signals output from the processor and digital signals output from the A / D converter. The method according to claim 8, And a sixth step of blocking the oscillation current and the modulation current supplied from the laser driving device to the laser diode when the determination device determines that the determination device is malfunctioning in the fifth step. The method according to claim 8, And a sixth step of blocking the optical signal transmitted from the laser diode to the optical line terminal device when the determination device determines that the determination device is malfunctioning in the fifth step.

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