KR20070059921A - Apparatus and methods of recovery architectures using tunable transceivers for optical transceivers in passive optical networks - Google Patents

Abstract

An apparatus and a method for protecting and recovering fixed transceivers using tunable transceivers in a PON(Passive Optical Network) are provided to cut expenses in constructing a PON by protecting N numbers of fixed transceivers in an OLT(Optical Line Terminal), which all ONUs(Optical Network Units) use in common, by using M numbers of tunable transceivers and offer differentiated services according to wavelengths by appointing protection/recovery priorities according to wavelengths and protecting a fixed transceiver having high priority first. An apparatus for protecting fixed transceivers in a PON comprising an OLT having N numbers of fixed transceivers(201) and ONUs(305,306) having a plurality of fixed transceivers comprises a state detection circuit part(303) and M numbers of tunable transceivers(202). The state detection circuit part(303), installed in the OLT, detects the fault state of an optical signal outputted from a fixed transceiver. The tunable transceivers(202), installed in the OLT, output a plurality of respectively different wavelength optical signals. The unable transceivers(202) extract a wavelength optical signal outputted from a fixed transceiver, which has generated a fault detected by the state detection circuit part(303), and recover the fault. The number(M) of tunable transceivers is smaller than the number(N) of fixed transceivers in the OLT.

Description

Apparatus and Methods of Recovery Architectures Using Tunable Transceivers for Optical Transceivers in Passive Optical Networks in Passive Optical Subscriber Networks

FIG. 1 is a diagram illustrating a protection recovery structure of a passive optical network (PON) proposed in the related art.

2 is a diagram showing the schematic structure of the N fixed wavelength transceiver protection recovery method using M variable wavelength transceivers according to the present invention (M << N).

3A is a diagram illustrating a fixed wavelength transceiver protection recovery structure in a WDM-PON using a variable wavelength transceiver according to an embodiment of the present invention.

3B is a diagram illustrating a fixed wavelength transceiver protection recovery structure in a hybrid WDM / TDM PON using a variable wavelength transceiver according to an embodiment of the present invention.

4 is a flowchart illustrating an operation of an optical line terminator (OLT) for protecting a fixed wavelength transceiver in a passive optical subscriber network according to the present invention.

5A is a flowchart of an operation in an optical subscriber station (ONU) for performing protection recovery of a passive optical subscriber network according to the present invention.

FIG. 5B is an operation flowchart of an optical subscriber station device (ONU) requesting a high reliability service for performing protection recovery of a passive optical subscriber network according to the present invention.

 Explanation of symbols on the main parts of the drawings

201: fixed wavelength transceiver 202: variable wavelength transceiver

303: state detection circuit

The present invention relates to a protection recovery structure in a passive optical network (PON: Passive Optical Network, PON), and more specifically, all optical subscriber terminal devices (ONU: Optical Network Unit, referred to as ONU) M: N (OLT) protects a shared optical line terminal (OLT), but protects the N fixed-wavelength transceivers in the OLT with M tunable transceivers. An optical module recovery method of the M << N) technique is provided.

In addition, by providing a recovery priority for each wavelength different, the optical module recovery method that provides a differentiated service by protecting the wavelength having a high priority first.

Due to the rapid increase of Internet users and the emergence of multimedia services that require large-capacity and high-speed transmission speeds, access networks are being considered as bottlenecks.

Accordingly, efforts have been made to implement an economical access network based on optical fibers to advance the access network. As a result, a technology called a passive optical netwrok (PON) has emerged.

PON technology is currently in the spotlight due to various advantages such as the infinite bandwidth that can be provided through optical fiber and low operation management cost. The PON technology is time division multiplexed (WDM) and wave length division multiplexed (WDM) depending on the multiplexing method used. Divided by).

TDM-PON is a technology that allows multiple subscribers to share one optical channel. However, TDM-PON can provide a low price per subscriber, but has a problem in that the number of subscribers is limited.

WDM-PON, on the other hand, is simple in structure and can provide enough bandwidth for subscribers, but WDM-PON is more expensive than TDM-PON because of its relatively high cost and high cost relative to the number of subscribers it can accommodate. Is considered to be the next generation access network technology.

As the access network is advanced, the survivability problem of the network, which is important in the backbone network, is also important in the access network.

Protective recovery technology is a technology that deals with the above-mentioned survivability problem, and when the network failure occurs, it is to solve the problem quickly to restore the network function.

The standardized documents related to the protective recovery structure proposed for the protective recovery technology are ITU-T G.983.1 and G.984.1, which describe a total of four protective recovery structures.

In addition, two of the above structures, which are considered economical and reliable, are selected and described in detail in G.984.5.

1 is a diagram illustrating a protection recovery structure in a passive optical network (PON) proposed in the related art.

FIG. 1 is one of the two structures, and it is a structure in which the trunk between OLT and OLT and RN commonly used by ONUs is dualized to increase efficiency versus economic efficiency.

Since only the parts used in common are duplicated, the additional cost used for the redundancy is divided and paid by all ONUs, and therefore, there is an advantage that it does not burden the ONUs.

However, since the above structure is a structure in which the entire OLT, which occupies most of the cost in constructing the PON, is duplicated, the cost is not so far.

Nevertheless, it is unimaginable not to duplicate the OLT of WDM-PON and Hybrid WDM / TDM PON using DWDM technology.

In order to construct an economical and survivable PON, the “optical module protection structure of a passive optical network” has proposed a patent to recover only an optical module in an OLT.

However, the above patent is also structured with the same number of backup optical modules to protect the optical modules in the OLT, and considering that there is little chance of the optical modules in the OLT failing at the same time, there is a little unnecessary extra cost. You can think about it.

Since the survivability of the network must be increased at a limited cost, the quality of service (QoS) may be considered in consideration of protection recovery.

 The wavelength for the differentiated service should have a higher priority than other wavelengths. There is no way to provide such a differentiated service.

For example, in the case of the above patent, when the optical module and the corresponding backup optical module fail, even if the wavelength of the optical module is a high priority wavelength, it must be discarded without any measures.

The present invention has been proposed to solve the conventional problems as described above, taking into account that there is almost no possibility that the optical module in the OLT failure at the same time, N fixed wavelength transceivers (hereinafter referred to as optical modules) in the OLT. M (M << N) Tunable Transceivers (hereinafter referred to as backup optical modules) are designed to protect the system.A single backup optical module protects multiple optical modules, thus redundancy of all optical modules. The aim is to significantly reduce the cost of redundancy while at the same time gaining the effect of doing so.

In addition, the present invention, the structure that can provide a differentiated service for each wavelength, when the optical module of the wavelength requiring the differentiated service is broken, by checking the priority of the wavelength that each backup optical module is responsible, low priority The backup optical module in charge of the wavelength of the preemption, can be assigned to the wavelength that requires differentiated services.

One embodiment of an optical transceiver protection recovery apparatus for a passive optical subscriber network according to the present invention for achieving the technical problem, OLT of the central base station including the N optical transceiver for outputting a fixed wavelength optical signal, each fixed wavelength optical In a passive optical subscriber network including an ONU of a subscriber end including a plurality of optical receivers for receiving a signal, a state detection circuit unit for detecting a failure phenomenon of the optical transmitter output optical signal; And a variable wavelength optical receiver for outputting a plurality of different wavelength optical signals; and extracting, from the variable wavelength optical receiver, a wavelength optical signal outputted by the optical transceiver which generates a disturbance detected by the state detection circuit unit. Recovering from the failure of the passive optical subscriber network.

One embodiment of an optical transceiver protection recovery method for a passive optical subscriber network according to the present invention for achieving the technical problem, OLT of the central base station including the N optical transceiver for outputting a fixed wavelength optical signal, each fixed wavelength optical In a passive optical subscriber network including an ONU of a subscriber end including a plurality of optical receivers for receiving a signal, detecting a failure of the optical transmitter output optical signal; And extracting and outputting a wavelength optical signal outputted by the optical transceiver that has generated the disturbance phenomenon detected in the state detection step by a variable wavelength optical transmitter which outputs a plurality of wavelength optical signals.

Advantageously, the number of variable wavelength transceivers is M, much less than the number of N fixed wavelength transceivers to be protected (M < N) to implement the M: N protection recovery technique.

Preferably, when the variable wavelength transceiver is not found and the available variable wavelength transceiver is not found, the variable wavelength transceiver can be preempted in consideration of the priority of the wavelength. In other words, by preempting the variable wavelength transceiver, the fixed fixed wavelength transceiver can be protected so that recovery can be performed by the priority of the wavelength.

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

2 is a diagram showing the schematic structure of the N fixed wavelength transceiver protection recovery method using M variable wavelength transceivers according to the present invention (M << N).

Unlike the previously proposed patent, in the present invention, a plurality of optical modules 201 are protected by a few backup optical modules 202.

That is, the backup optical module 202 is configured in parallel with the optical module, and the SD (Signal Degrade) phenomenon occurs in the optical module 201, hereinafter referred to as SD. When signal failure (SF) is detected, a cause of the phenomenon is detected. As a result, the optical module 201 causes the failure. In this case, it finds a backup optical module 202 ready to use and acts as a substitute for the optical module 201.

Here, the number of backup optical modules protecting the optical module is selected by the network provider, and if a high network availability is desired, it is preferable to have a large number of backup optical modules.

However, as long as the entire OLT fails, all optical modules rarely fail at the same time. Therefore, the number of backup optical modules should be determined in consideration of this point.

3A is a diagram illustrating a fixed wavelength transceiver protection recovery structure in a WDM-PON using a variable wavelength transceiver according to an embodiment of the present invention.

As shown, the OLT consists of a backup optical module 202 for protecting the optical module as well as an optical module 201 that is responsible for transmitting and receiving each wavelength.

Referring to FIG. 3A, the backup optical module 202 is configured in parallel with the optical module 201 as described with reference to FIG. 2, and when SD and SF occur in the optical module 201, The function will be replaced. Here, the determination of whether the optical module 201 operates normally is made by the state detection circuit 303.

In addition, the backup optical module 202 and the optical module 201 are connected in parallel to the remote base station (Remote Node 304, hereinafter referred to as RN), so that 1 + 1 for the ONU 306 which desires high reliability service. By operating in a manner to provide a desired level of service, to provide a service having a normal reliability to provide a service by operating in a 1: 1 manner to the ONU (305).

At this time, two optical modules exist in the ONU 306 that receives 1 + 1 service, and one optical module is connected to the optical module 201 of the OLT, and the other optical module is connected to the OLT. Connected with the backup optical module 202 to protect the optical module 201, the ONU transmits and receives a high quality signal.

3B is a diagram illustrating a fixed wavelength transceiver protection recovery structure in a hybrid WDM / TDM PON using a variable wavelength transceiver according to an embodiment of the present invention.

As shown, it is similar to the recovery method in the WDM PON, and the result is almost the same as when the present invention is applied to the WDM-PON.

4 is a flowchart of an OLT operation when a backup optical module is added to protect an optical module of the OLT and to provide differentiated wavelength-specific services according to the present invention.

The OLT measures the quality of the transmitted and received optical signal, and if the quality of the optical signal is larger or smaller than a value within a predetermined range, the OLT determines that SF or SD has occurred and tracks the cause of the SF or SD.

If it is determined that the optical module that transmits and receives the optical signal as a result of the tracking is broken (401), a protection recovery operation for protecting the optical module is started.

The protection recovery operation for the optical module of the OLT begins by searching for a backup optical module that is not currently used (402).

When a searchable backup optical module is found (403), the searched backup optical module is used to substitute the function of the optical module (404).

In the search result 402, there may be no backup optical module that can be used.

When several optical modules in the OLT have already failed, the backup optical modules are all used to protect the failed optical modules. In this case, the failure of the optical module cannot be recovered.

If all wavelengths have the same priority, the above situation is not very important, but unfortunately, there may be wavelengths that require high priority among the wavelengths.

 In this case, even though the optical module responsible for the wavelength having the high priority has failed, since the backup optical module has already been occupied by another wavelength, the optical module cannot be recovered.

In order to prevent the above case, if there is no backup optical module available as a result of searching the available backup optical module, the priority of the wavelength which the failed optical module is responsible for is searched (405), and the backup optical module already used is This is compared with the priority of the wavelength in charge (406).

As a result, when the priority of the wavelength which the currently broken optical module is in charge is higher than the priority of the wavelength which is in charge by the backup optical module, the above-mentioned backup optical module is preoccupied and the light which carries the high priority wavelength is in charge. Act on the function of the module (407).

As a result of the determination, if the priority is the same or lower, failing to protect the failed optical module (408).

5A is a flowchart of an operation in an optical subscriber station (ONU) for performing protection recovery of a passive optical subscriber network according to the present invention.

FIG. 5A is a flowchart illustrating an operation of an ONU used to provide a basic repair service in case that only one fixed wavelength optical module exists in the ONU, and FIG. 5B illustrates one fixed wavelength optical module in the ONU, and If there is another fixed wavelength optical module, there is a flow chart of operation in the ONU used to provide a high reliability recovery service.

The ONU receives the optical signal transmitted from the OLT (501), and the ONU determines the occurrence of SD and SF by measuring the intensity of the LOL and the signal of the received optical signal (502).

 If the measurement resulted in SD and SF, the OLT is notified of the SD and SF occurrence (503). The OLT receiving the SD and SF generation message determines whether or not the fixed optical module in the OLT is broken. To substitute for the function of the failed optical module.

In this process, the ONU will experience some interruption during the switching time from the optical module to the backup optical module.

FIG. 5B is an operation flowchart of an optical subscriber station device (ONU) requesting a high reliability service for performing protection recovery of a passive optical subscriber network according to the present invention.

Referring to FIG. 5B, the ONU simultaneously transmits and receives an optical signal from an optical module of an OLT and a backup optical module using the same wavelength as the optical module (504). Each transmitted / received optical signal checks the strength of the signal to determine whether SD or SF is generated (505). As a result, if SD and SF are generated, the OLT is notified of SD and SF generation (506).

 Knowing the SD and SF generation of the optical module, OLT enables the recovery of the 1 + 1 method by using another backup optical module that is not being used to replace the function of the failed optical module.

On the other hand, ONU receives a signal transmitted from an optical module that does not occur when SD and SF occur, regardless of whether SD and SF occur, and if the SD and SF do not occur, the signal level among the two optical signals received. This good optical signal is received (507).

The description and the contents of the drawings described above exemplarily describe a form of protection of an optical module (fixed wavelength transceiver) using a backup optical module (variable wavelength transceiver) according to the present invention, and the present invention is limited to such description. no. In addition, it will be apparent to those skilled in the art that various modifications and imitations can be made without departing from the scope of the technical idea of the present invention.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, the present invention protects the N fixed wavelength transceivers of the OLT jointly used by all ONUs using M variable wavelength transceivers (M <N), thereby saving a large part of the cost in constructing a passive optical subscriber network. It can cut costs, which can dramatically lower the costs that ONUs have to pay.

In addition, by providing protection recovery priority for each wavelength, the fixed optical module having a high priority may be protected first to provide differentiated services for each wavelength.

Claims (7)

In a passive optical subscriber network comprising an OLT of a central base station including N optical transceivers for outputting a fixed wavelength optical signal, and an ONU of a subscriber end including a plurality of optical transceivers for receiving each fixed wavelength optical signal, A state detection circuit unit for detecting a failure phenomenon of the optical transmitter output optical signal; And A variable wavelength optical transceiver for outputting a plurality of different wavelength optical signals; The optical transmitter and receiver of the passive optical subscriber network, characterized in that to recover the failure of the passive optical subscriber network by extracting the wavelength optical signal output from the optical transceiver that has generated the disturbance detected by the state detection circuit unit from the variable wavelength optical receiver Protection recovery device. The method of claim 1, And M variable wavelength optical transmitters, wherein the variable wavelength optical transmitters are smaller than the number (N) of the optical transmitters. The method of claim 1, And the state detecting circuit unit and the variable wavelength optical transceiver are located at an OLT of the central base station. The method of claim 1, wherein the disorder phenomenon Recovery of the optical transceiver of a passive optical subscriber network, characterized in that the intensity of the output optical signal of the optical receiver, dispersion of the output optical signal of the optical receiver, the phenomenon that the output optical signal of the optical receiver is not detected. Device. In a passive optical subscriber network comprising an OLT of a central base station including N optical transceivers for outputting a fixed wavelength optical signal, and an ONU of a subscriber end including a plurality of optical transceivers for receiving each fixed wavelength optical signal, Detecting a state of failure of the optical transmitter output optical signal; And And extracting and outputting a wavelength optical signal outputted by the optical transceiver that has generated a disturbance detected in the state detection step by a variable wavelength optical transmitter that outputs a plurality of wavelength optical signals. How to recover optical transceiver protection of a network. The method of claim 5, And the M variable wavelength optical transceiver, wherein the variable wavelength optical transceiver is smaller than the number N of the optical transmitters. 7. The optical receiver of claim 6, wherein there are a plurality of optical transceivers that cause the disturbance. Detecting whether the variable wavelength optical transmitter is available; Prioritizing according to the QoS provided by the optical transceiver which generated the obstacle when there is no variable wavelength optical transceiver available;  Prioritizing according to QoS provided by the variable wavelength optical transceiver in use; Converting a wavelength optical signal output by the variable wavelength optical transceiver in use at the lowest rank into a wavelength output by the optical transceiver having generated the disturbance at the highest rank; And The wavelength output by the optical transceiver which generated the obstacle phenomenon until the optical transmitter which has generated the disturbance phenomenon higher than the variable wavelength optical transmitter in use is recovered. Repeating the switching to the optical transceiver receiver recovery method of a passive optical subscriber network comprising a.

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