KR20140068776A - Optical Amplifier(OA)-based reach extender and passive optical network system including the reach extender - Google Patents

Abstract

Disclosed are a time and wavelength division multiplexing-passive passive optical network (TWDM-PON) system and a distance extension device included in the same. According to an embodiment, the TWDM-PON system includes: a service provider terminal which provides a service in a time division multiplexing method using optical signals having different wavelengths; a subscriber terminal which includes a plurality of optical network units (ONU) using a service provided from one of a plurality of optical line terminals with an arbitrary wavelength selected according to the wavelength control by the service provider terminal; an optical distribution network which delivers multi-wavelength downlink optical signals transmitted from the service provider terminal to the subscriber terminal and multi-wavelength uplink optical signals transmitted from the subscriber terminal to the service provider terminal; and a distance extension device which includes one among a downlink optical amplifier for amplifying the multi-wavelength downlink optical signals at the same time and an uplink optical amplifier for amplifying the multi-wavelength uplink optical signals at the same time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical amplifier based distance extension apparatus and a passive optical network system including the optical amplifier.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive optical network (PON), and more particularly, to an optical amplifier based distance extension apparatus and a PON system including the same.

A time division multiplexing (TDM-PON) type optical network (TDM-PON) such as EPON (Ethernet Passive Optical Network) or GPON (Gigabit capable PON) uses optical signals of wavelengths of up and down, And uses an optical splitter that does not require power to connect domestic users with subscribers. Because of this feature, TDM-PON has been widely deployed and successfully deployed around the world. Among them, GPON was distributed in North America and Europe. In 2010, ITU-T issued the G.987 XG-PON standard recommendation, which is 10G-GPON. FSAN (Full Service Access Network), a group consisting of major telecommunication carriers and equipment manufacturers related to optical network technologies, is a standardization group of ITU-T SG15 Q2 group and recently developed a next generation passive optical network (NG- (Time and Wavelength Division Multiplexing (TWDM) passive optical network (TWDM-PON)) is adopted as the main technology of PON2. TWDM-PON is discussed in ITU-T as a G.989.x standard recommendation.

1 is a block diagram showing a schematic configuration of a TWDM-PON system. As shown in FIG. 1, in the TWDM-PON system, a wavelength division multiplexing (WDM) system in which a plurality of optical signals having different wavelengths are multiplexed with a TDM system signal transmission technology (for example, XG- WDM) signaling technology to provide broadband services to subscribers. At this time, an optical line terminal (OLT) can be physically implemented as a plurality of entities, and has a function of transmitting and receiving multi-wavelength light from a system point of view (multiple wavelength transceiver). The Optical Distribution Unit (ODN) divides the downstream signals of the received multiple wavelengths (? 1,? 2,? 3,? 4) and transmits them to each Optical Network Unit (ONU) ), Or multiple wavelength signals (? 5,? 6,? 7,? 8) combining upstream signals of a predetermined wavelength received from a plurality of ONUs to the OLT. In addition, the ONUs each have a tunable transceiver, so that the service can be used at an arbitrary wavelength. However, in terms of network management, the wavelength used by each ONU can be controlled by an optical line termination (OLT).

On the other hand, since the PON system has a limitation on the link budget, there is a certain restriction on the deployment of the light network. Here, the link budget means an allowable loss amount on an optical link in which a transmitted signal can be transmitted without error when transmitting and receiving a signal. For example, in a TDM-PON system, a loss in a main optical link may be largely caused by a loss occurring in an optical fiber constituting the optical transmission line and an optical intensity loss due to branching of the optical splitter. The loss in the optical link can be the same in the TWDM-PON system. The smaller the link budget, the closer the distance between the OLT and the ONU can be. Therefore, a method for increasing the link budget for efficient deployment of the optical network has been proposed in the PON system.

As a method for increasing the link budget, that is, the transmission distance of an optical signal, a method of reducing branching of a splitter, a method of adding a distance extending device (Reach Extender, RE), and the like are considered. According to the former method, the branching of the splitter can be reduced to reduce the loss. However, this method has a disadvantage in that the number of ONUs that can be serviced decreases as the number of branches of the splitter decreases. As a result, the latter method of adding a distance extension device is considered to be more effective.

FIG. 2 is a diagram conceptually showing an increase in transmission distance, that is, a link budget, by adding a distance extending device in a conventional PON system. In FIG. 2, the link budget of the existing PON system is Budget ₂ . 2, a distance extension device RE 120 is added to an existing PON system including an OLT 110, a splitter 130, and a plurality of ONUs 140. By adding the distance extension device (RE 120) to the existing PON system, the link budget of the entire PON system can be increased to Budget ₁ + Budget ₂ .

There are two types of distance extension devices, one is an optical amplifier (OA) and the other is an optical-electro-optical (OEO) regenerator. An optical amplifier provides gain in optical power. The photoelectric converters receive the optical signal, reshape and retime it in the electrical domain, and then transmit it back in the optical domain.

3 is a block diagram showing an example of the structure of a conventional photoelectric light-based distance expanding apparatus. Referring to FIG. 3, it is known that the optical signal received at the receiving end Rx of the photoelectric light-based distance expanding device 122 is changed and amplified through an electric circuit and transmitted again through the transmitting terminal Tx . The photoelectric light-based distance extension device 122 is advantageous in the TDM-PON in which the up signal (Up: 1 ') and the down signal (Dn:? 1) are one channel.

However, the distance extension device 122 shown in FIG. 3 is not suitable for a TWDM-PON system in which all the uplink and downlink signals are plural (for example, four or more channels). FIG. 4 is a diagram showing a configuration when the distance expanding apparatus of FIG. 3 is directly applied to a TWDM-PON system. 4, the distance extension device 124 applied to the TWDM-PON system requires DeMUX and MUX for the up signals Up1 'to 8' and the down signals Dn: [lambda] 1 to [lambda] 8, A large number of receiving terminals (Rx), electric circuits (Logic), and transmitting terminals (Tx) must be used.

One problem to be solved by the present invention is to provide an optical amplifier-based distance extension device applicable to a TWDM-PON system and a TWDM-PON system including the same.

Another problem to be solved by the present invention is to provide an optical amplifier-based distance extension device that can be applied to a TWDM-PON that is simpler and more suited to characteristics of a burst mode uplink signal, and a TWDM-PON system including the same.

According to an aspect of the present invention, there is provided a time and wavelength division multiple passive optical network (TWDM-PON) system, which provides a service in a time division multiplexing manner using optical signals of different wavelengths A service provider apparatus including a plurality of optical line devices (OLTs), a plurality of optical networks using a service provided from one of the plurality of optical line equipments (OLTs) at a wavelength selected according to wavelength control from the service provider apparatus A wavelength division multiplexing optical network for transmitting a multi wavelength downlink optical signal transmitted from the service provider apparatus to the subscriber apparatus and a multi wavelength uplink optical signal transmitted from the subscriber apparatus to the service provider apparatus, (ODN), a downstream optical amplifier for simultaneously amplifying the multi-wavelength downlink optical signal, And an upstream optical amplifier for simultaneously amplifying the multi-wavelength upstream optical signal.

According to an aspect of the embodiment, the upstream optical amplifier may be a semiconductor-based optical amplifier. In this case, the semiconductor-based optical amplifier may be a gain-fixed semiconductor optical amplifier or a Raman optical fiber amplifier.

According to another aspect of the present invention, the distance extension device includes a downlink splitter for branching the multi-wavelength downlink optical signal from the service provider apparatus, a monitoring signal including information necessary for controlling an operation state of the downlink optical amplifier, And a multiplexer for multiplexing the monitoring signal generated by the built-in optical network terminal at the specific wavelength and the optical signal of the specific wavelength among the multiplexed downstream optical signals branched by the down- And a wavelength tunable transceiver for transmitting at a corresponding wavelength.

In one example, the monitoring signal may include one or more of information related to the R / S physical interface supported by the communicating OLT, information associated with the downstream optical amplifier, and information related to general indicators of the optical amplifier. More specifically, the information related to the R / S physical interface includes at least one of a managed entity ID, an administrative state, an operational state, an optical signal level, a lower optical power threshold, a lower optical threshold, an upper optical threshold, a transmit optical level, a lower transmit power threshold, an upper transmit power threshold, And a mode (Usage mode). Alternatively, the information related to the downstream optical amplifier includes at least one of a management entity ID, a management state, an operation mode, an operation state, an input optical signal level, an input optical signal lower limit threshold, an input optical signal upper limit threshold, , An output optical signal upper limit threshold, and an RS splitter coupling ratio. Alternatively, the information related to the general indicator of the optical amplifier may include a management entity ID, a gain, a lower gain threshold, an upper gain threshold, a target gain, a device temperature, One or more of a temperature lower limit threshold, a device temperature upper limit threshold, a device bias current, an amplifier saturation output power, an optical amplifier saturation gain, and an optical amplifier noise figure . ≪ / RTI >

As another example, the distance extension device may include an up splitter for splitting the multi-wavelength uplink optical signal from the subscriber device, and a wavelength tuning device for receiving an optical signal of a specific wavelength from the multi-wavelength uplink optical signal branched by the up- The monitoring signal generated in the built-in optical network terminal may further include information required to control an operation state of the upstream optical amplifier. More specifically, the information required to control the operation state of the upstream optical amplifier includes at least one of a management entity ID, a management state, an operation mode, an operation state, an RE upstream amplifier pointer, a total optical reception signal table a receive signal level table, a burst receive signal level table, a lower receive optical threshold, a lower receive optical threshold, a transmit optical signal level, A transmit optical signal lower transmit optical threshold, and a transmit optical signal upper transmit optical threshold.

As another example, the embedded optical network terminal may be sequentially connected to the plurality of optical line terminals and may transmit the monitoring signal to the connected optical line terminal. Alternatively, the built-in optical network terminal may be connected to the optical line terminal according to a control signal of any optical line terminal among the plurality of optical line terminals, and may transmit the monitoring signal to the optical line terminal to which the optical line terminal is connected.

According to another aspect of the present invention, the distance extension device includes a downlink splitter for branching the multi-wavelength downlink optical signal from the service provider apparatus, a monitoring signal including information necessary for controlling an operation state of the downlink optical amplifier, A downlink optical demultiplexer for demultiplexing the multiwavelength downlink optical signals branched by the downlink splitter, a downlink optical demultiplexer for demultiplexing the downlink optical signals by the downlink optical demultiplexer, A multi-wavelength light source for transmitting a wavelength-dependent signal including a monitoring signal output from the built-in optical network terminal, and a multi-wavelength light source including a multiplexer for multiplexing the wavelength- And may further include an optical transceiver. In this case, the distance extension device includes: an upward splitter for branching the multi-wavelength upstream optical signal from the subscriber device; an upstream optical demultiplexer for demultiplexing the multi-wavelength upstream optical signal branched by the upward splitter; And an uplink multi-wavelength receiver for receiving the uplink optical signal demultiplexed by the optical demultiplexer, wherein the monitoring signal generated in the built-in optical network terminal controls the operation state of the upstream optical amplifier And may further include information necessary for control.

According to another aspect of the present invention, there is provided a distance expanding apparatus for increasing a link budget of a time and wavelength division multiple-passive optical network (TWDM-PON) system, the service provider apparatus of the TWDM- A built-in optical network terminal (embedded ONT) for generating a monitoring signal including information required to control the operation state of the downstream optical amplifier, and a multiplexing / demultiplexing unit And a wavelength variable transceiver for receiving an optical signal of a specific wavelength among the multi-wavelength downstream optical signals and transmitting the monitoring signal generated by the built-in optical network terminal to a wavelength corresponding to the specific wavelength.

According to an aspect of the embodiment, the monitoring signal includes at least one of information related to the R / S physical interface supported by the communicating OLT, information related to the downstream optical amplifier, and information related to general indicators of the optical amplifier .

According to another aspect of the present invention, the distance extension device includes an up splitter for splitting the multi-wavelength uplink optical signal from the subscriber device, and a downlink splitter for splitting the optical signal of a specific wavelength among the multi-wavelength uplink optical signals branched by the up- The monitoring signal generated in the built-in optical network terminal may further include information required to control an operation state of the upstream optical amplifier.

According to another aspect of the present invention, the embedded optical network terminal may be sequentially connected to the plurality of optical line terminals and may transmit the monitoring signal to the optical line terminal to which the optical line terminal is connected. Alternatively, the built-in optical network terminal may be connected to the optical line terminal according to a control signal of any optical line terminal among the plurality of optical line terminals, and may transmit the monitoring signal to the optical line terminal to which the optical line terminal is connected.

According to the embodiment of the present invention, the link budget of the TWDM-PON system is increased by applying the distance expansion device, which is simple in structure, suitable for the burst mode uplink signal characteristic, and capable of communicating with each OLT, to the TWDM- Can be expanded. Further, each of the plurality of OLTs constituting the service provider apparatus can obtain the channel-by-channel management information of the TWDM-PON system, so that the service provider further monitors the operation state of the inserted distance expanding apparatus, System management is possible.

1 is a diagram showing an example of a configuration of a TWDM-PON system.
FIG. 2 is a diagram for explaining how to increase a link budget by inserting a distance expanding device in a PON system. FIG.
3 is a block diagram illustrating the structure of a conventional photoelectric-based distance expanding apparatus.
FIG. 4 is a block diagram illustrating a structure of a photoelectric-based distance expanding apparatus when the distance expanding apparatus of FIG. 3 is applied to a TWDM-PON system.
FIG. 5 is a block diagram showing a schematic configuration of an optical amplifier-based distance expanding device that can be inserted into a TWDM-PON system according to an embodiment of the present invention.
6 is a configuration diagram illustrating a configuration of a TWDM-PON system including a distance expanding apparatus according to an embodiment of the present invention.
7 is a configuration diagram illustrating a configuration of a TWDM-PON system including a distance extension device according to another embodiment of the present invention.
8 is a configuration diagram showing a configuration of a TWDM-PON system including a distance expanding apparatus according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms used are terms selected in consideration of the functions in the embodiments, and the meaning of the terms may vary depending on the user, the intention or custom of the operator, and the like. Therefore, the meaning of the terms used in the following embodiments is defined according to the definition when specifically defined in this specification, and unless otherwise defined, it should be interpreted in a sense generally recognized by those skilled in the art.

FIG. 5 is a block diagram showing a schematic configuration of an optical amplifier-based distance expanding device that can be inserted into a TWDM-PON system according to an embodiment of the present invention. 5, the optical amplifier based distance extension apparatus 200 includes a first WDM filter 210, a downstream optical amplifier 220, a second WDM filter 230, and an upstream optical amplifier 240 do.

The first and second WDM filters 210 and 230 are diplexers and divide the wavelength of the down signal Dn and the up signal Up, respectively, by band. More specifically, the first WDN filter 210 divides the wavelength of the down signal Dn going from left to right and the up signal Up going from the lower end to the left. The second WDM filter 230 also divides the wavelength of the down signal Dn going from left to right and the up signal Up going from the right to the bottom. Each of the first and second WDM filters 210 and 230 may be replaced with an optical circulator.

According to this embodiment, the downstream optical amplifier 220 and the upstream optical amplifier 240 can simultaneously amplify WDM signals of several channels. That is, it is possible to simultaneously amplify the multi-wavelength downstream optical signals Dn: [lambda] 1 to [lambda] 8 and amplify the multi-wavelength upstream optical signals Up: lambda 1 'to lambda 8' simultaneously. As described above, according to the embodiment of the present invention, the downstream optical amplifier 220 and the upstream optical amplifier 240 can simultaneously amplify optical signals of multiple wavelengths, and are suitable for use as a distance extension device of the TWDM-PON system .

Although FIG. 5 shows that both of the optical amplifiers 220 and 240 are included in both the upward and downward directions in the distance expanding apparatus 200, this is merely an example. Alternatively, the distance extension device 200 may include only one of the downstream optical amplifier 220 and the upstream optical amplifier 240, and the other may include another type of optical amplifier (for example, a photoelectric optical amplifier) .

According to an aspect of this embodiment, the upstream optical amplifier 240 may be a semiconductor optical amplifier. This is because, in the case of the TWDM-PON system, the upward signal has a bursty characteristic. In the TWDM-PON system, burst mode signals of various channels are simultaneously input to the upstream optical amplifier 240. The upstream optical amplifier 240, which is formed of a semiconductor-based optical amplifier, distorts the multi-wavelength burst mode signal Because it can be amplified without. For example, the upstream optical amplifier 240 may be a gain fixed type semiconductor optical amplifier or a Raman optical fiber amplifier, but is not limited thereto.

On the other hand, the downstream optical amplifier 220 may comprise an EDFA (Erbium-doped Fiber Amplifier), which is just one example. For example, in order to miniaturize and integrate the distance-extending device 200 including the downstream optical amplifier 220 and the upstream optical amplifier 240, all the optical amplifiers including the downstream optical amplifier 220 are configured with a semiconductor-based optical amplifier can do.

Although not shown in the drawing, an optical bandpass filter (OBF) may be additionally provided at output ends of the downstream optical amplifier 220 and the upstream optical amplifier 240, respectively. The optical band pass filter OBF limits the bandwidth of the amplified spontaneous emission (ASE) amplified by the respective optical amplifiers 220 and 240 so that the ASE-ASE beat noise and the ASE- Thereby achieving better performance by reducing the ASE-based power-offset. However, if an optical band pass filter (OBF) is used, a limited wavelength range for the transmitter may be required.

6 is a configuration diagram illustrating a configuration of a TWDM-PON system including a distance expanding apparatus according to an embodiment of the present invention. 6, the TWDM-PON system 300 includes a service provider apparatus 310, an optical distribution network (ODN) 320, and a subscriber apparatus 330, ), The optical distribution network 320, and the subscriber unit 330 are merely exemplary. In addition, the TWDM-PON system 300 according to the embodiment of the present invention further includes a distance extending device 340 inserted in the optical distribution network 320. The distance extension device 340 may be disposed between the service provider device 310 and the optical distribution network 320, but is not limited thereto. For example, the distance extending device 340 may be installed at the front end and / or the rear end of the splitter of the optical distribution network 330.

The service provider device 310 may include one or more optical line devices (OLT). According to the present embodiment, the individual OLT constituting the service provider apparatus 310 may be a device for providing service at multiple wavelengths. Alternatively, the individual OLTs that make up the service provider device 310 may be devices that provide services at a single wavelength, in which case the service provider device 310 includes a plurality of OLTs. In FIG. 6, the service provider apparatus 310 is shown as including eight NGPON2 OLTs (Port-1 to Port-8), which is only exemplary. Here, the service provider apparatus 310 including a plurality of, for example, eight NGPON2 OLTs may have a hybrid mode combining the TDM scheme and the WDM scheme. Such a configuration is suitable as a structure for accommodating a plurality of identical services or heterogeneous service links using various optical wavelength signals. In this case, assuming that each NGPON2 OLT accommodates one TDM PON link, one optical distribution network accommodates n identical or heterogeneous networks, and each service can be divided into wavelength bands of the signal to be used .

The user equipment 330 includes a plurality of optical network units (ONUs). It is shown in Figure 6 that a total of m ONUs (1 ... n, n + 1, ..., m) are included, which is only exemplary. For example, all or part of the user equipment 330 may be an NGPON2 ONU, which can receive wavelength multiplexed downlink optical signals transmitted from a plurality of NGPON2 OLTs. To this end, each of the user devices 330 may comprise a wavelength selectable transceiver, i. E. A tunable transceiver.

The distance extension device 340 is intended to increase the link budget of the TWDM-PON system 300 that accommodates multiple wavelengths. The basic configuration and operation principle of this distance extending device 340 may be the same as the distance extending device 200 shown in FIG. The distance extension device 300 includes a first WDM filter 347 and an upstream optical amplifier 348 for amplifying an optical signal and a downstream optical amplifier 348 for amplifying a downstream optical signal Dn: and a second WDM filter 345 and a downstream optical amplifier 346 for optical signal amplification with respect to the wavelengths λ1 to λ8. The distance extension device included in the TWDM-PON system 300 does not necessarily have to be one, and one or a plurality of distance extension devices (R.E. 322) may be additionally included in the optical distribution network 320 if necessary.

Generally, since such a distance extending device 340 is installed at a remote location, the network operator is required to monitor the operation state of the distance extending device 340 essentially for its maintenance and management. In addition, the existing distance extension devices for G-PON and XG-PON are connected to one OLT, so that the network manager can monitor the status through communication between the OLT and the distance extension device. However, in the distance extension device according to the embodiment of the present invention, Since the OLT 340 is connected to the service provider apparatus 310 composed of a plurality of OLTs, each of the plurality of OLTs and the distance extending apparatus 340 must communicate using a plurality of communication connection channels.

The distance extension apparatus 340 according to the embodiment of the present invention may further include a downward splitter 341, a wavelength tunable transceiver 342, an embedded optical network terminal (ONT) 343 . Here, the downward splitter 341 is for branching the downstream optical signal. The wavelength tunable transceiver 342 receives the optical signal of the specific wavelength among the downstream optical signals branched by the downward splitter 341 and transmits the upstream optical signal of the corresponding wavelength. The distance extension device 340 may further include a microprocessor 344, which functions to manage the operating state of the optical module.

The tunable optical transceiver 342 communicates with only one of the OLTs of the plurality of OLTs constituting the service provider apparatus 310 at a specific wavelength and / or communicates with each of the plurality of OLTs constituting the service provider apparatus 310 You may. To this end, the built-in ONT 343 may be communicatively coupled to an OLT corresponding to a specific wavelength received by the tunable transceiver 342 among a plurality of OLTs. That is, the built-in ONT 343 collects information to transfer the necessary information for maintenance and management of the distance-extending device 340 to the OLT, which is communicated through the wavelength variable optical transceiver 342, and transmits the collected information to the OLT The wavelength tunable transceiver 342 can be controlled to transmit. For example, when the wavelength tunable transceiver 342 selects λ1 and is connected to the NGPON2 OLT Port-1, the built-in ONT 343 can transmit the operation information of the distance extension device 340 to the NGPON2 OLT Port-1 .

According to an aspect of the present embodiment, the wavelength tunable transceiver 342 periodically changes the reception wavelength to transmit each OLT included in the service provider apparatus 310, that is, the OLT (NGPON2 OLT Port-1 to NGPON2 OLT Port- And the built-in ONT 343 are communicatively connected to each other. In this case, the reception wavelength of the wavelength tunable transceiver 342 can be sequentially changed in accordance with a preset order. Accordingly, all connected OLTs can be designed to receive the operation information and the like of the distance extending device 340. [ According to another aspect of this embodiment, the wavelength tunable transceiver 342 may be in communication with all or some of the OLTs that provide all the OLTs or services included in the service provider device 310, All or some of the OLTs may be sequentially connected to the OLTs in the order specified by the MGPON2 OLP Port-1, or may be sequentially connected to all or some of the OLTs only when there is a request from the specific OLT.

According to the embodiment of the present invention, the built-in ONT 343 can generate a monitoring signal including information related to the R / S physical interface supported by the OLT connected to the communication. The generated monitoring signal can be transmitted to the OLT through the wavelength tunable transceiver 342. Here, the R / S physical interface refers to the ONU physical interface to the optical distribution network (ODN). The information related to the R / S physical interface supported by the communication-connected OLT includes, for example, a managed entity ID, an administrative state, an operational state, an optical signal a lower optical power threshold, an upper optical threshold, a transmit optical level, a lower transmit power threshold, a transmit power upper threshold (upper), an optical signal lower limit threshold, a transmit power threshold, and a usage mode.

The built-in ONT 343 generates a monitoring signal including information related to the downstream optical amplifier 346, and the generated monitoring signal can be transmitted to the OLT communicatively connected through the wavelength tunable transceiver 342. The information related to the downstream optical amplifier 346 includes, for example, a management entity ID, a management state, an operation mode, an operation state, an ARC, an ARC interval, an input optical signal level, an input optical signal lower limit threshold, An output optical signal level, an output optical signal lower limit threshold, an output optical signal upper limit threshold, and an RS splitter coupling ratio.

The built-in ONT 343 also generates a monitoring signal including general indicators of the optical amplifiers 346 and 348 and the generated monitoring signal can be transmitted to the OLT communicatively connected through the wavelength tunable transceiver 342. The general indicators of the optical amplifiers 346 and 348 include a management entity ID, a gain, a lower gain threshold, an upper gain threshold, a target gain, The device temperature lower limit threshold, the device temperature upper limit threshold, the device bias current, the optical amplifier saturation output power, the optical amplifier saturation gain, and the optical amplifier noise figure. Or more.

7 is a configuration diagram illustrating a configuration of a TWDM-PON system including a distance extension device according to another embodiment of the present invention. 7, the TWDM-PON system 400 includes a service provider apparatus 410, an optical distribution network (ODN) 420, and a subscriber apparatus 430, ), The optical distribution network 420, and the subscriber device 430 are only exemplary. The TWDM-PON system 400 according to an embodiment of the present invention further includes a distance extending device 440 inserted into the optical distribution network 420. For example, the distance extension device 440 may be disposed between the service provider device 410 and the optical distribution network 420, but is not limited thereto. The distance extending device 440 of the TWDN-PON system 400 according to the embodiment of the present invention further includes an upward splitter 450 and a tunable receiver 449, Which is different from the distance expanding device 340 of the TWDM-PON system 300, which will be described later in detail.

The service provider device 410 may include one or more OLTs. According to the present embodiment, the individual OLT constituting the service provider apparatus 410 may be a device for providing service at multiple wavelengths. Alternatively, the individual OLTs that make up the service provider device 410 may be devices that provide services at a single wavelength, in which case the service provider device 410 includes a plurality of OLTs. In FIG. 7, the service provider apparatus 410 is shown as including eight NGPON2 OLTs (Port-1 to Port-8), which is only exemplary. Here, the service provider apparatus 410 including a plurality of, for example, eight NGPON2 OLTs may have a hybrid mode combining the TDM scheme and the WDM scheme. Such a configuration is suitable as a structure for accommodating a plurality of identical services or heterogeneous service links using various optical wavelength signals. In this case, assuming that each NGPON2 OLT accommodates one TDM PON link, one optical distribution network accommodates n identical or heterogeneous networks, and each service can be divided into wavelength bands of the signal to be used .

The user equipment 430 includes a plurality of ONUs. It is shown in Figure 7 that a total of m ONUs (1 ... n, n + 1, ..., m) are included, which is only exemplary. For example, all or a portion of the user equipment 430 may be an NGPON2 ONU, which can receive wavelength multiplexed downlink optical signals transmitted from a plurality of NGPON2 OLTs. To this end, each of the user devices 430 may include a wavelength selectable transceiver, that is, a tunable transceiver.

The distance extension device 440 is intended to increase the link budget of the TWDM-PON system 400 that accommodates multiple wavelengths. The basic configuration and operation principle of the distance extending device 440 may be the same as the distance extending device 200 shown in FIG. To this end, the distance-extending apparatus 400 includes a first WDM filter 447 and an upstream optical amplifier 448 for amplifying the optical signal with respect to the upstream optical signals Up: lambda 1 'to lambda 8' and a second WDM filter 445 and a downstream optical amplifier 446 for optical signal amplification with respect to the wavelengths λ1 to λ8. The distance extension device included in the TWDM-PON system 400 does not necessarily have to be one, and one or a plurality of distance extension devices (R.E. 422) may be additionally included in the optical distribution network 420 if necessary.

Generally, since the distance expanding device 440 is installed at a remote location, the network operator is required to monitor the operation state of the distance expanding device 440 essentially for maintenance and management thereof. In addition, the existing distance extension devices for G-PON and XG-PON are connected to one OLT, so that the network manager can monitor the status through communication between the OLT and the distance extension device. However, in the distance extension device according to the embodiment of the present invention, Since the OLT 440 is connected to the service provider apparatus 410 composed of a plurality of OLTs, each of the plurality of OLTs and the distance extending apparatus 440 must communicate using a plurality of communication connection channels.

The distance extension device 440 may further include a downward splitter 441, a wavelength tunable transceiver 442, and an embedded optical network terminal 443. Here, the downward splitter 441 is for branching the downstream optical signal. The wavelength tunable transceiver 442 receives the optical signal of the specific wavelength from the downstream optical signal branched by the downward splitter 441 and transmits the upstream optical signal of the wavelength corresponding thereto. The distance extension device 440 may further include a microprocessor 444, which functions to manage the operating state of the optical module.

Also, as described above, the distance extending device 440 according to the embodiment of the present invention further includes an upward splitter 450 and a tunable receiver 449. Upstream splitter 450 is for branching the upstream optical signal. The wavelength tunable receiver 449 is for selecting and receiving a specific wavelength from the upstream optical signals branched from the upward splitter 450. The distance extending device 440 may further provide information on the upstream optical signal to the OLT through the uplink splitter 450 and the wavelength tunable receiver 449.

The wavelength tunable optical transceiver 442 communicates with only one OLT out of a plurality of OLTs constituting the service provider apparatus 410 at a specific wavelength and / or communicates with each of the plurality of OLTs constituting the service provider apparatus 410 You may. To this end, the built-in ONT 443 may be communicatively coupled to an OLT corresponding to a specific wavelength received by the tunable transceiver 442 from among a plurality of OLTs. That is, the built-in ONT 443 collects information to transfer the information necessary for maintenance and management of the distance-extending device 440 to the OLT communicatively connected through the wavelength tunable optical transceiver 442, and transmits the collected information to the OLT The wavelength tunable transceiver 442 can be controlled to transmit. For example, if the wavelength tunable transceiver 442 selects λ1 and is connected to the NGPON2 OLT Port-1, the built-in ONT 443 can transmit the operation information of the distance extension device 440 to the NGPON2 OLT Port-1 .

According to an aspect of the present embodiment, the wavelength tunable transceiver 442 periodically changes the reception wavelength to transmit each OLT included in the service provider apparatus 410, that is, the OLT (NGPON2 OLT Port-1 to NGPON2 OLT Port- And the built-in ONT 443 are communicatively connected to each other. In this case, the reception wavelength of the wavelength tunable transceiver 442 can be sequentially changed in accordance with a preset order. Accordingly, all connected OLTs can be designed to receive the operation information of the distance extending device 440 and the like. According to another aspect of this embodiment, the wavelength tunable transceiver 442 may be in communication with all or some of the OLTs providing all the OLTs or services included in the service provider device 410, All or some of the OLTs may be sequentially connected to the OLTs in the order specified by the MGPON2 OLP Port-1, or may be sequentially connected to all or some of the OLTs only when there is a request from the specific OLT.

According to this embodiment of the present invention, the built-in ONT 443 can generate a monitoring signal including information related to the R / S physical interface supported by the OLT communicatively connected. The generated monitoring signal can be transmitted to the OLT through the wavelength tunable transceiver 442. Here, the R / S physical interface refers to the ONU physical interface to the optical distribution network (ODN). The information related to the R / S physical interface supported by the communication-connected OLT includes, for example, management object ID, management status, operation status, ARC, ARC interval, optical signal level, optical signal lower limit threshold, optical signal upper limit threshold, Transmission optical signal level, transmission power lower limit threshold, transmission power upper limit threshold, and a usage mode.

The built-in ONT 443 generates a monitoring signal including information related to the upstream optical amplifier 448, and transmits the generated monitoring signal to the OLT connected to the wavelength variable optical communication. Here, the information related to the upstream optical amplifier 448 includes, for example, a management entity ID, a management state, an operation mode, an operation state, an RE upstream amplifier pointer, a total optical reception signal table a receive signal level table, a burst receive signal level table, a lower receive optical threshold, a lower receive optical threshold, a transmit optical signal level, A transmit optical signal lower transmit optical threshold, an upper transmit optical threshold, and the like.

The built-in ONT 443 generates a monitoring signal including information related to the downstream optical amplifier 446, and the generated monitoring signal can be transmitted to the OLT communicatively connected through the wavelength tunable transceiver 442. The information related to the downstream optical amplifier 446 includes, for example, a management entity ID, a management state, an operation mode, an operation state, an input optical signal level, an input optical signal lower limit threshold, an input optical signal upper limit threshold, An output optical signal lower limit threshold, an output optical signal upper limit threshold, and an RS splitter coupling ratio.

The built-in ONT 443 generates a monitoring signal including general indicators of the optical amplifiers 446 and 448, and the generated monitoring signal can be transmitted to the OLT communicatively connected through the wavelength tunable transceiver 442. The general indicators of the optical amplifiers 446 and 448 include a management entity ID, a gain, a gain lower limit threshold, a gain upper limit threshold, a target gain, a device temperature, a device temperature lower limit threshold, a device temperature upper limit threshold, Saturation output power, optical amplifier saturation gain, optical amplifier noise figure, and the like.

8 is a configuration diagram showing a configuration of a TWDM-PON system including a distance expanding apparatus according to another embodiment of the present invention. The TWDM-PON system 500 shown in FIG. 8 is similar in overall configuration to the TWDM-PON system 400 shown in FIG. 7, but instead of the wavelength tunable transceiver 442, the multi-wavelength optical transceivers 542a and 542b 542c, and 542d, and the multi-wavelength optical receivers 549a and 549b are provided in place of the tunable receiver 449. [ Hereinafter, embodiments of the present invention will be described, focusing on differences from the TWDM-PON system 400 shown in FIG. Therefore, the matters described above with reference to FIG. 7 can be applied to the matters not specifically described in this embodiment.

8, the TWDM-PON system 500 includes a service provider apparatus 510, an optical distribution network (ODN) 520, and a subscriber apparatus 530. [ The detailed configuration of each of the service provider apparatus 510, the optical distribution network 520, and the subscriber apparatus 530 shown in Fig. 8 is also only exemplary. The TWDM-PON system 500 according to an embodiment of the present invention further includes a distance extending device 540 inserted into the optical distribution network 520. In one example, the distance extension device 540 may be disposed between the service provider device 510 and the optical distribution network 520, but is not limited thereto.

The distance extension device 540 of the TWDN-PON system 500 may include a multiplexing wavelength receiver such as an upstream demultiplexer 549b and an uplink multi-wavelength optical receiver 549a together with an up- . The upstream multi-wavelength optical receiver 549a may be a photodiode array, which is exemplary only. The configuration of such a multi-wavelength receiving apparatus is similar to the distance extending apparatus 440 of the TWDM-PON system 400 shown in FIG. 7, and more specifically, the upstream optical demultiplexer 549b and the upward multi- The receiver 549a corresponds to the tunable receiver 449 of Fig. However, according to the embodiment, the distance extending device 540 may not include the multi-wavelength light receiving devices 549a and 549b together with the upward splitter 550. In this case, May be similar to the distance extension device 340 shown in FIG.

The distance extension device 540 of the TWDM-PON system 500 further includes a multi-wavelength transmitting / receiving device. The multiple wavelength transmitting and receiving apparatus may include a downstream demultiplexer 542a, a downstream multi-wavelength optical receiver 542b, a multi-wavelength light source 542c, and a multiplexer 542d. The downlink optical demux 542a performs wavelength demultiplexing on the downlink optical signal and the downlink multi-wavelength optical receiver 542b receives the signals on the wavelength demultiplexed by the downlink optical demux 542a . The downstream multi-wavelength optical receiver 542b may be configured as a photo diode array, but is not limited thereto. The multi-wavelength light source 542c transmits the wavelength-dependent signal, and the multiplexer 542d multiplexes the transmission signal output from the multi-wavelength light source 542c. The multi-wavelength light source 542c may be a light emitting diode array, but is not limited thereto. The multi-wavelength optical transceivers 542a, 542b, 542c, and 542d according to this embodiment correspond to the wavelength tunable transceivers 342 and 442 of FIG. 6 or 7 from a functional point of view.

The TWDM-PON system according to the embodiment of the present invention can be variously modified in addition to the above-described configuration.

For example, the multi-wavelength optical transceivers 542a, 542b, 542c and 542d in the distance extension devices 440 and 540 of the TWDM-PON system shown in Figs. 7 and 8 respectively correspond to the wavelength tunable transceiver 442 The multi-wavelength light receiving devices 549a and 549b correspond to the tunable receiver 449. The distance extending device (not shown) according to the modified example includes multi-wavelength optical transmitting / receiving devices 542a, 542b, 542c, and 542d Tunable receiver 449, or a combination of wavelength tunable transceiver 442 and multi-wavelength optical receiver 549a, 549b.

As another example, in addition to branching the downstream optical signal and / or the upstream optical signal to obtain wavelength information, the distance extending apparatus according to the embodiment of the present invention may further include a downstream optical amplifier 346, 446, 546, 8) and / or a wavelength tunable receiver or a multi-wavelength optical receiver that receives an optical signal branched by a splitter provided additionally at the rear end of the upstream optical amplifiers 348, 448, and 548. According to this, information on the downstream signal and the upstream signal as well as the optical signal amplified by the downstream / upstream optical amplifier can be acquired and transmitted to the service provider apparatus.

The above description is only an example of the present invention, and the technical idea of the present invention should not be interpreted as being limited by this embodiment. The technical idea of the present invention should be specified only by the invention described in the claims. Therefore, it is apparent to those skilled in the art that the above-described embodiments may be modified and embodied in various forms without departing from the technical spirit of the present invention.

Claims (20)

A service provider apparatus including a plurality of optical line devices (OLT) for providing services in a time division multiplexing manner using optical signals of different wavelengths;
A subscriber unit including a plurality of optical network units (ONUs) using a service provided from one of the plurality of optical line units (OLT) at a wavelength selected according to wavelength control from the service provider apparatus;
An optical distribution network (ODN) for transmitting a multi-wavelength downlink optical signal transmitted from the service provider apparatus to the subscriber apparatus and a multi-wavelength uplink optical signal transmitted from the subscriber apparatus to the service provider apparatus; And
And a distance extending device including at least one of a downstream optical amplifier for simultaneously amplifying the multi-wavelength downlink optical signal and an upstream optical amplifier for simultaneously amplifying the multi-wavelength uplink optical signal. The time and wavelength division multiplexing passive optical network (TWDM-PON) system. The method according to claim 1,
Wherein the upstream optical amplifier is a semiconductor-based optical amplifier. 3. The method of claim 2,
Wherein the semiconductor-based optical amplifier is a gain-fixed semiconductor optical amplifier or a Raman optical fiber amplifier. 2. The apparatus of claim 1, wherein the distance extension device
A downstream splitter for branching the multi-wavelength downlink optical signal from the service provider apparatus;
An embedded ONT for generating a monitoring signal including information necessary for controlling the operation state of the downstream optical amplifier; And
A wavelength variable transceiver for receiving an optical signal of a specific wavelength among the multiple wavelength downstream optical signals branched by the downward splitter and transmitting the monitoring signal generated by the built-in optical network terminal to a wavelength corresponding to the specific wavelength Time and wavelength division multiplexed passive optical network system. 5. The method of claim 4,
Wherein the monitoring signal comprises at least one of information related to an R / S physical interface supported by the communicating OLT, information associated with the downstream optical amplifier, and information related to a general indicator of the optical amplifier. Wavelength Division Multiple - Passive Optical Network System. 6. The method of claim 5,
The information related to the R / S physical interface includes at least one of a managed entity ID, an administrative state, an operational state, an optical signal level, a lower optical threshold An upper optical threshold, a transmit optical level, a lower transmit power threshold, an upper transmit power threshold, and a usage mode ), Wherein the time and wavelength division multiplexed passive optical network system comprises one or more of the following. 6. The method of claim 5,
The information related to the downstream optical amplifier includes at least one of a management entity ID, a management state, an operation mode, an operation state, an input optical signal level, an input optical signal lower limit threshold, an input optical signal upper limit threshold, an output optical signal level, An optical signal upper limit threshold, and an RS splitter coupling ratio. ≪ Desc / Clms Page number 19 > 6. The method of claim 5,
The information related to the general index of the optical amplifier includes at least one of a management entity ID, a gain, a lower gain threshold, an upper gain threshold, a target gain, a device temperature, Includes one or more of a threshold value, a device temperature upper limit threshold, a device bias current, an optical amplifier saturation output power, an optical amplifier saturation gain, and an optical amplifier noise figure Time multiplexed wavelength division multiplexed optical network system. 5. The apparatus of claim 4, wherein the distance extension device
An uplink splitter for branching the multi-wavelength uplink optical signal from the subscriber unit; And
Further comprising a tunable receiver for receiving an optical signal of a specific wavelength from the multi-wavelength upstream optical signals branched by the upward splitter,
Wherein the monitoring signal generated in the built-in optical network terminal further includes information necessary to control an operation state of the upstream optical amplifier. 10. The method of claim 9,
The information required to control the operation state of the upstream optical amplifier includes a management entity ID, a management state, an operation mode, an operation state, an RE upstream amplifier pointer, a total optical receive signal level table A receive signal level table according to a burst, a lower receive optical threshold, a lower receive optical threshold, a transmit optical signal level, a transmit optical signal level, A lower transmit optical threshold, and an upper transmit optical threshold. ≪ Desc / Clms Page number 19 > 5. The method of claim 4,
Wherein the built-in optical network terminal is sequentially connected to the plurality of optical line terminals and transmits the monitoring signal to an optical line terminal to which the optical line terminal is connected. 5. The method of claim 4,
Wherein the built-in optical network terminal is connected to an optical line terminal according to a control signal of any one optical line terminal among the plurality of optical line terminals and transmits the monitoring signal to an optical line terminal to which the optical line terminal is connected. Passive optical network system. 2. The apparatus of claim 1, wherein the distance extension device
A downstream splitter for branching the multi-wavelength downlink optical signal from the service provider apparatus;
An embedded ONT for generating a monitoring signal including information necessary for controlling the operation state of the downstream optical amplifier; And
A downlink multi-wavelength receiver for receiving a downlink optical signal demultiplexed by the downlink optical demultiplexer, a downlink multi-wavelength receiver for demultiplexing the multi-wavelength downlink optical signal branched by the downlink splitter, Further comprising a multiwavelength light source for transmitting a wavelength-dependent signal including an output monitoring signal, and a multi-wavelength optical transmitter / receiver for multiplexing wavelength-wise signals output from the multiwavelength light source. Wavelength Division Multiple - Passive Optical Network System. 14. The method of claim 13,
Wherein the monitoring signal comprises at least one of information related to an R / S physical interface supported by the communicating OLT, information associated with the downstream optical amplifier, and information related to a general indicator of the optical amplifier. Wavelength Division Multiple - Passive Optical Network System. 14. The apparatus of claim 13, wherein the distance extension device
An uplink splitter for branching the multi-wavelength uplink optical signal from the subscriber unit; And
An upstream optical demultiplexer for demultiplexing the multiwavelength upstream optical signal branched by the upstream splitter and an upstream multiwavelength receiver for receiving the upstream optical signal demultiplexed by the optical demultiplexer, Lt; / RTI >
Wherein the monitoring signal generated in the built-in optical network terminal further includes information necessary to control an operation state of the upstream optical amplifier. A distance extension apparatus for increasing the link budget of a time and wavelength division multiple-passive optical network (TWDM-PON) system,
A downstream splitter for branching a multi-wavelength downlink optical signal from a service provider apparatus of the TWDM-PON system;
An embedded ONT for generating a monitoring signal including information necessary for controlling the operation state of the downstream optical amplifier; And
And a wavelength variable transceiver for receiving an optical signal of a specific wavelength among the multiple wavelength downstream optical signals branched by the downward splitter and for transmitting the monitoring signal generated by the built-in optical network terminal to a wavelength corresponding to the specific wavelength Distance extension device. 17. The method of claim 16,
Wherein the monitoring signal comprises at least one of information related to the R / S physical interface supported by the communicating OLT, information associated with the downstream optical amplifier, and information associated with a general indicator of the optical amplifier. Device. 17. The apparatus of claim 16, wherein the distance extension device
An uplink splitter for branching the multi-wavelength uplink optical signal from the subscriber unit; And
Further comprising a tunable receiver for receiving an optical signal of a specific wavelength from the multi-wavelength upstream optical signals branched by the upward splitter,
Wherein the monitoring signal generated in the built-in optical network terminal includes information required to control an operation state of the upstream optical amplifier. 17. The method of claim 16,
Wherein the built-in optical network terminal is sequentially connected to the plurality of optical line terminals and transmits the monitoring signal to an optical line terminal to which the optical line terminal is connected. 17. The method of claim 16,
Wherein the built-in optical network terminal is connected to the optical line terminal according to a control signal of any one optical line terminal among the plurality of optical line terminals, and transmits the monitoring signal to the optical line terminal to which the optical line terminal is connected.

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