KR100915317B1 - Optical Network Unit and Power control method for it's optical transceiver - Google Patents

Abstract

The present invention relates to an optical network terminating device and a method for controlling an optical transmitting / receiving unit power thereof, wherein an optical network unit (ONU: optical network unit) constituting a passive optical network (PON) system has an abnormality of its optical transmitting / receiving unit. By self-diagnosing the failure, if the abnormality is implemented, the optical transmitter / receiver is turned off, thereby preventing communication failures of the remaining normal optical network termination units (ONUs) caused by the continuous light output of the optical network termination unit (ONU) in which the failure occurs. It is to prevent.

Description

Optical Network Terminator and Power Control Method for Its Optical Transceiver

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical network unit (ONU: optical network unit) constituting a passive optical network (PON) system, and more particularly, to a power control technology of an optical transmission / reception unit of an optical network terminator (ONU).

PON (Passive Optical Network) is an optical subscriber construction method that provides high-speed services based on fiber optics to businesses, SOHO, and homes, and a single optical line termination (OLT: Optical Line Termination) system using a splitter on an optical cable. It is a method to connect an end device (ONU: Optical Network Unit).

PON includes TDM (A) -PON using time division multiplexing and WDM (A) -PON of wavelength division multiplexing. Time-division multiplexing includes ATM-based ATM-PON, Ethernet-based (G) E-PON, and G-PON using common frame protocols, and WDM-PON for wavelength-division multiplexing.

(G) E-PON is an inexpensive, easy-to-use shared optical subscriber network that eliminates active devices such as regenerators and amplifiers in outdoor devices, minimizes the number of optical cables to be installed, and reduces the number of optical ports in central base stations. Passive equipment of the (G) E-PON consists of a single-wavelength optical cable, a passive optical splitter / coupler, a connector and a splice. Network devices such as OLT or multiple ONUs are located at both ends of the PON, as shown in FIG. The optical signal transmitted through the PON is divided by the optical splitter / coupler and loaded onto multiple optical fibers or combined and transmitted to one optical fiber according to whether the direction of light is upstream or downstream. In this structure of E-PON system, data collision may occur upstream. In order to avoid this upstream collision, the OLT performs discovery as shown in FIG. 2.

Referring to FIG. 2, the OLT transfers a gate message, which is a multi-point control protocol (MPCP) message, to all ONUs. Except for registered ONUs, the ONU wishing to register transmits a register_request message upstream after a random delay at the time of grant start.

Meanwhile, the OLT opens a discovery window for a set time and receives a registration request message. The OLT calculates a round trip time (RTT) for each ONU existing at different distances through the registration request message, allocates a logical link identifier (LLID), and transmits a registration message. When the gate message is sent to the ONU with the LLID again, the discovery handshake is completed by finally sending a register_ack message to the OLT.

After discovery, the frame transmission / reception method is described in detail. First, in the downstream, when the LLID of the ONU registered with the OLT is inserted into the preamble of the frame, the ONU only sends the frame having its own LLID to the user interface (UI). Send to. In contrast, in the upstream, the OLT checks the queue information of each ONU through a report message periodically received from the ONU, and dynamically allocates upstream time slots by granting all ONUs.

If the ONU is upstream at other times without responding to the OLT report message request due to a fiber disconnection of the fiber drop section of a particular ONU, malfunction of the ONU system, or otherwise responding to the OLT-allocated time slot, In case of sending an MPCP message or a user frame, the OLT forcibly deregisters a malfunctioning ONU in order to guarantee the service of another ONU.

At this time, the laser of the optical module is always turned on due to a malfunction of the laser control signal of a specific ONU, the laser control signal and the control signal input of the optical module are set opposite to each other, or the laser control signal is irrespective of the laser control signal due to the failure of the optical module. Is always on, the OLT deems all ONUs unblocked and prevents upward access, considering that not all ONUs are responding correctly, as well as bad ONUs, while a single ONU takes over the entire upstream time slot.

In some cases, when one ONU light output continues and monopolizes the track, idle signals are output at intervals other than the time interval allocated to itself, so that other ONUs are idle even if they try to link with the OLT. Because it is intermingled with the signal, the OLT may not recognize the link request of a particular ONU at all.

Common to the above examples is that the OLT cannot know which ONU has a problem. In this case, since the OLT must check all ONUs, there is a problem that normal ONUs are not serviced until a problem is found.

That is, since the E-PON method is designed to transmit and receive data by assigning a line to each ONU by TDM method as shown in FIG. 3, each ONU is assigned a time interval (1, 2 in the figure). , 3) can only output the optical signal, and as shown in Fig. 4, an interval other than the allotted time interval (ONU1 is allocated to output the optical signal only in the square one-hour interval on the right, but occupies the entire time). If an optical signal is outputted from, the communication between the other ONU and the OLT sharing the same line will be interrupted. In the case of the E-PON method, since one line is shared by up to 32 ONUs, if the optical output is continuously generated due to the failure of an optical module of one ONU, communication errors may occur in the remaining 31 ONUs. At this time, if the failure to find a faulty ONU and quickly solve the problem, serious problems in service provision.

Accordingly, the present inventors diagnose an optical module unit (ONU: Optical Network Unit) constituting a passive optical network (PON) system by itself to diagnose whether the optical module is abnormal or not. By implementing the power off, if the optical output is continuously generated due to the failure of the optical module of one ONU, the optical network termination device and the optical transmission and reception unit power control method that can solve the problem of communication failure in the remaining ONU I did research.

The present invention has been invented under the above-described purpose, and an optical network unit (ONU: Optical Network Unit) constituting a passive optical network (PON) system diagnoses its own optical transmission / reception unit by itself and is abnormal. It is an object of the present invention to provide an optical network termination device and an optical transmission / receiver power control method thereof for turning off the optical transmitter / receiver, if any.

According to an aspect of the present invention for achieving the above object, when it is determined that the optical network termination device according to the present invention diagnoses the abnormality of the optical transmitting and receiving unit, there is an abnormality, it is characterized in that to turn off the power of the optical transmitting and receiving unit. .

According to another aspect of the present invention, the optical transmitter and receiver control method of the terminal device according to the present invention monitors the optical output of the optical transmitter and receiver of the optical network termination unit (ONU) in real time to monitor the logic signal according to the optical output situation. And outputs a power control signal according to a result of the comparison by comparing the output logic signal and the TX enable signal (TX enable siganl), and the optical signal of the optical network termination unit ONU according to the output power control signal. It is characterized in that the on / off control of the power supply of the transceiver unit.

As described above, the optical network termination device and the optical transmitter / receiver power control method thereof according to the present invention include a plurality of optical network termination devices (ONUs) that share the same line with an optical line termination (OLT). If a failure occurs in any of the optical network termination units (ONU), the failure is caused by the self-diagnosis of the optical network termination unit (ONU) in which the failure has occurred and the power failure of the optical transmission and reception unit of the optical network termination unit (ONU) in which the failure has occurred. There is a useful effect that can prevent the occurrence of communication failure of the remaining normal optical network termination (ONU) due to the continuous light output of the generated optical network termination (ONU).

1 is a schematic diagram of a passive optical network (PON) system;

2 is a flowchart illustrating a discovery performing procedure of an optical line terminal (OLT);

3 is a schematic diagram showing an allocated time interval of each optical network terminator (ONU);

FIG. 4 is a schematic diagram showing a time interval occupied by an optical network terminator ONU in which a failure occurs when a failure of any one optical network terminator ONU occurs. FIG.

5 is a block diagram according to an embodiment of an optical network termination device according to the present invention;

6 is a view illustrating an example of a signal comparison result by the signal comparison unit of the optical network termination device according to the present invention;

7 is a flowchart illustrating a process of controlling the power transmission and receiving unit of the optical network termination unit (ONU) according to the present invention.

<Explanation of symbols for main parts of the drawings>

100: optical line terminal device (OLT) 200: optical network terminal device (ONU)

210: optical transmitter and receiver 211: optical transmitter

211a: laser diode (LD) 211b: laser driver

212: light receiving unit 212a: second photodiode PD

212b: Amplifier 220: Self diagnosis unit

221: light output monitoring unit 222: signal comparison unit

230: control unit 300: track

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention.

5 is a block diagram according to an embodiment of an optical network termination device according to the present invention. A passive optical network (PON) system includes a plurality of optical network termination devices (ONUs) that share the same line 300 with an optical line termination (OLT) 100, as shown in FIG. Optical Network Unit).

The optical line terminal (OLT) 100 registers each optical network terminator (ONU) 200 including assigning a line to each optical network terminator (ONU) 200 in a time division multiplexing (TDM) manner. And release.

On the other hand, the optical network termination device 200 according to the present invention, as shown in Figure 5, comprises a light transmitting and receiving unit 210, a self-diagnostic unit 220, and a control unit 230. The optical transmitter / receiver 210 serves to transmit and receive an optical signal under the control of the controller 230. The self-diagnostic unit 220 diagnoses an abnormality of the optical transmitter / receiver 210. The controller 230 controls the whole apparatus, and turns off the power of the optical transmitter / receiver 210 when it is determined that there is an error by the self-diagnosis unit 220.

Therefore, the optical network termination unit (ONU) 200 according to the present invention diagnoses the abnormality of the optical transmitter / receiver 210 through the self-diagnostic unit 220, if it is determined that there is an error, the optical transmitter / receiver 210 Passive Optical Network (PON) system consisting of a plurality of optical end devices (ONU) (200) sharing the same line 300 with the optical line terminal (OLT) 100 by the self cut off power of It is possible to prevent the occurrence of communication failures of the remaining normal optical end devices (ONU) due to the continuous light output of the optical network end device (ONU) in which a failure in the.

Specifically, the optical transmitter 210 includes the optical transmitter 211 and the optical receiver 212, and performs the role of transmitting and receiving the optical signal under the control of the controller 230 to be described later. The optical transmitter 211 includes a laser diode (LD) 211a for outputting light and a laser driver 211b for driving the laser diode LD. Meanwhile, the optical receiver 212 may include a second photo diode (PD) 212a for receiving an optical signal and an amplifier (Amp) for amplifying the optical signal received by the second photo diode (PD). 212b. Meanwhile, an optical network termination device (not shown) includes a multiplexing / demultiplexing unit (not shown) for multiplexing and demultiplexing signals transmitted and received between the optical transmission and reception unit 210 and the optical line terminal device (OLT) 100 of the optical network termination device 200. It is preferable that 200 further contains.

On the other hand, the self-diagnosis unit 220 diagnoses the abnormality of the optical transmission and reception unit 210. Specifically, the self diagnosis unit 220 may be implemented to include an optical output monitoring unit 221 and a signal comparison unit 222. The light output monitoring unit 221 monitors the light output of the light transmission / reception unit 210 and outputs a logic signal (high or low signal) depending on whether the light output is performed. For example, the light output monitoring unit 221 detects the light emitting state of the laser diode LD 211a and outputs a logic signal according to the light emitting state of the laser diode LD. Diode).

The signal comparison unit 222 outputs a power control signal by comparing an optical transmission activation signal TX enable siganl of the optical transmission and reception unit 210 with a logic signal output from the optical output monitoring unit 221. At this time, the optical transmission enable signal TX enable siganl is output by the controller 230 to be described later. Preferably, the signal comparison unit 222 exclusively combines the optical transmission activation signal TX enable siganl of the optical transmission and reception unit 210 and the logic signal output from the optical output monitoring unit 221. It is preferably implemented to operate.

If the optical transmission activation signal TX enable siganl has a 'High' value in a normal state (a state in which the optical signal is transmitted), the optical transmitter 211 of the corresponding optical transmitter 210 is activated to activate the laser driver. Since 211b applies a bias voltage to the laser diode LD 211a, the laser diode LD 211a emits light. Then, the first photodiode PD, which is the light output monitoring unit 221, receives the light and accordingly outputs a 'High' value.

In addition, when the optical transmission activation signal TX enable siganl has a 'Low' value in a normal state (a state in which the optical signal is transmitted), the laser driver 211b biases the laser diode LD 211a. Since no bias voltage is applied, the laser diode (LD) 211a does not emit light. Then, since the light of the first photodiode PD, which is the light output monitoring unit 221, is not received, a 'Low' value is output.

However, in the abnormal state (error state), even though the laser diode LD 211a emits light due to the TX enable siganl having a high value, the first photodiode PD Although the laser diode (LD) 211a does not emit light due to the failure to receive light and outputs a 'Low' value or the TX enable signal (TX enable siganl) has a 'Low' value, the first The photodiode (PD) recognizes the light as if it received light and outputs a 'High' value.

Then, the signal comparison unit 222 may perform an XOR operation on the optical transmission activation signal TX enable siganl of the optical transmission and reception unit 210 and the logic signal output from the optical output monitoring unit 221. In this case, the results as shown in Fig. 6 are obtained. That is, when the TX enable siganl and the output logic signal are all high or all low, the power output signal outputs a low value. On the other hand, when any one of the optical transmission active signal (TX enable siganl) and the output logic signal is 'High', the other is 'Low' abnormal state is outputting a 'High' value.

The controller 230 controls the whole apparatus, and turns off the power of the optical transmitter / receiver 210 when it is determined that there is an error by the self-diagnosis unit 220. Specifically, the controller 230 controls the power of the optical transmitter / receiver on / off according to the power control signal output from the signal comparator 222.

At this time, if the power control signal output from the signal comparing unit 222 is a 'High' signal, the controller 230 determines that an error and turns off the power of the optical transmitter / receiver 210. ) On the other hand, the controller 230 determines that the power control signal output by the signal comparator 222 is a 'Low' signal, and maintains the power of the optical transmitter / receiver on.

Therefore, by doing so, the optical network termination unit (ONU) 200 according to the present invention diagnoses the abnormality of the optical transmitter / receiver 210 through the self-diagnostic unit 220 and determines that there is an abnormality. Passive light consisting of a plurality of optical network termination unit (ONU) (200) sharing the same line 300 with the optical line terminal device (OLT) 100 by cutting off the power of the optical transmission and reception unit 210 by itself The above-described objectives can be prevented because communication failures of the remaining ONUs due to the continuous light output of the ONUs in which a failure in a passive optical network (PON) system occurs are prevented. Can be achieved.

Referring to Figure 7 looks at the power transmission and reception unit control process of the optical network termination unit (ONU) according to the present invention having the configuration as described above. 7 is a flowchart illustrating a process of controlling an optical transmitter / receiver power supply of an optical network termination unit (ONU) according to the present invention.

Each of a plurality of optical network termination units (ONUs) 200 sharing the same line 300 with an optical line terminal device (OLT) 100 constituting a passive optical network (PON) system is performed in step S110. Real-time monitoring (Monitoring) of the light output of its own light transmitting and receiving unit 210 through the self-diagnostic unit 220.

In operation S120, the self-diagnostic unit 220 outputs a logic signal according to an optical output situation monitored by the light output monitoring unit 221. 222 compares the logic signal output by the step S120 and the optical transmission active signal (TX enable siganl) of the optical transmission and reception unit 210 of the optical network termination unit (ONU), and compares the signal in step S140 The unit 222 outputs a power control signal according to the comparison result of the step S130.

Then, the control unit 230 of the optical network termination unit (ONU) receives the output power control signal in step S150, and according to the output power control signal, the optical transmission and reception unit 210 of the optical network termination unit (ONU) By controlling the on / off power of the self), it is possible to prevent communication failures of the remaining normal optical network terminators (ONUs) due to the continuous light output of the defective optical network terminator (ONU).

According to an additional aspect of the present invention, in step S130, the self-diagnostic unit 220 performs an exclusive logical sum of the logic signal and the optical transmission activation signal TX enable siganl of the optical transmitter and receiver through the signal comparison unit 222. It is preferable to implement the (XOR) operation.

Then, as described above, the signal comparison unit 222 performs an exclusive logical sum of the optical transmission activation signal TX enable siganl of the optical transmission and reception unit 210 and the logic signal output from the optical output monitoring unit 221. XOR) to output the power control signal as shown in FIG. 6 in step S140. That is, when the TX enable siganl and the output logic signal are all high or all low, the power output signal outputs a low value. On the other hand, when any one of the optical transmission active signal (TX enable siganl) and the output logic signal is 'High', the other is 'Low' abnormal state is outputting a 'High' value.

Accordingly, when the power control signal output by the signal comparator 222 is a 'High' signal in step S150, the controller 230 determines an error, and the power of the optical transmitter / receiver 210 is determined. OFF. On the other hand, the controller 230 determines that the power control signal output by the signal comparator 222 is a 'Low' signal, and maintains the power of the optical transmitter / receiver on.

Therefore, by doing so, the optical network terminator (ONU) according to the present invention self-diagnoses the abnormality of the optical transmitter / receiver, and if it is determined that there is an abnormality, the optical network terminator (OLT) is the same as the optical line terminal apparatus (OLT) by automatically shutting off the power of the optical transmitter / receiver. Remaining normal fiber termination due to the continuous light output of the ONU having a failure in a passive optical network (PON) system consisting of a plurality of ONUs 200 sharing a line Since the occurrence of communication failure of the devices ONU can be prevented, the above-mentioned object can be achieved.

While the invention has been described with reference to the preferred embodiments, which are referred to by the accompanying drawings, it is apparent that various modifications are possible without departing from the scope of the invention within the scope covered by the following claims from this description. .

The present invention can be used industrially in a passive optical network (PON) system, such as FTTC (Fiber To The Curb) or FTTC (Fiber To The Home) service method.

Claims (13)

delete delete delete In the optical network unit (ONU: Optical Network Unit) constituting a passive optical network (PON) system, An optical transmitter and receiver; An optical output monitoring unit for monitoring an optical output of the optical transmitting and receiving unit and outputting a logic signal according to whether the optical output is present, an optical transmission activation signal TX enable siganl, and the optical output monitoring unit A self-diagnostic unit including a signal comparison unit configured to output a power supply control signal by performing an exclusive logical sum (XOR) operation on the output logic signal; A control unit which controls the overall apparatus, and controls on / off power of the optical transmitting / receiving unit according to a power control signal output from the signal comparing unit; Optical network termination device comprising a. The method of claim 4, wherein The control unit: And determining that the power control signal output by the signal comparator is an 'high' signal and turning off the power of the optical transmitter and receiver. The method of claim 4, wherein The control unit: And determining that the power control signal output by the signal comparator is a 'low' signal, and maintaining the power of the optical transmitter / receiver in an on state. The method according to any one of claims 4 to 6, The optical transmitting and receiving unit: A laser diode (LD) for outputting light; A laser driver for driving the laser diode LD; Optical network terminating device comprising a light transmitting unit comprising. The method of claim 7, wherein The light output monitoring unit: And a first photodiode (PD) for detecting a light emitting state of the laser diode (LD) and outputting a logic signal according to the light emitting state of the laser diode (LD). The method of claim 8, The optical transmitting and receiving unit: A second photo diode (PD) for receiving an optical signal; An amplifier (Amp) for amplifying the optical signal received by the second photodiode (PD); Optical network termination device further comprising a light receiving unit comprising. delete In the power control method of the optical transceiver unit of the optical network unit (ONU: optical network unit) constituting a passive optical network (PON) system, a) real-time monitoring the optical output of the optical transmitter and receiver of the optical network termination unit (ONU); b) outputting a logic signal in accordance with the light output situation monitored by step a); c) comparing the logic signal output by step b) with an exclusive logical sum (XOR) operation of the optical transmission activation signal TX enable siganl of the optical transmission / reception unit of the optical network terminator (ONU); d) outputting a power control signal according to the comparison result of step c); e) controlling the on / off power of the optical transmitting / receiving unit of the corresponding optical network termination unit (ONU) according to the power control signal output by step d); An optical transmission and reception unit power supply control method of an optical network terminating device comprising a. The method of claim 11, In step e), if the power control signal output by step d) is a 'High' signal, it is determined as an error, and the power of the optical transmitter / receiver of the optical network termination unit ONU is turned off. Power transmission method of the optical transmission and reception unit of the optical network termination device. The method of claim 11, In the step e), if the power control signal output by the step d) is a 'low' signal, it is determined to be normal, and the power of the optical transmitter / receiver of the corresponding optical network termination unit (ONU) is turned on. Power transmission method of the optical transmission and reception unit of the optical network termination device.