JP2007295507A - Optical transmission system, and optical repeater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical repeater which is used for a PON optical transmission system and into which a management function of the repeater is easily introduced. <P>SOLUTION: The optical repeater is provided with optical signal processing sections 21, 22, 23 connected between a first optical transmission line 2 at a center side and a second optical transmission line 3 at a subscriber side in the optical transmission lines 2, 3 connected between at least a subscriber side optical line terminal 7-1 and a center side optical line terminal 1, an optical multiplexer/demultiplexer 20 connected to the first optical transmission line 2 or the second optical transmission line 3, a management optical line terminal 24 connected to the first optical transmission line 2 or the second optical transmission line 3 via the add-drop optical multiplexer 20; and a management function section 26 for transmitting/receiving a repeater supervisory signal to/from the management optical line terminal 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical transmission system and an optical repeater, and more particularly to a PDS type optical transmission system and an optical repeater thereof.

  In optical networks such as FTTH and CATV, a PDS (Passive Double Star) type optical transmission system is used in which an optical transmission line connected to a center is branched by a passive splitter and installed to a plurality of subscribers' homes.

  In such an optical transmission system, a splitter is connected to an optical fiber drawn out from an OSU (Optical Subscriber Unit) in an optical line terminator (OLT) of a center to a user side, and is branched into a plurality by the splitter. The optical transmission line is connected to an optical network unit (ONU) of a plurality of users via an optical fiber.

  In a PDS type optical transmission system in which an OLT and a plurality of ONUs are connected by an optical fiber and a splitter, a configuration in which an optical repeater is connected to the optical transmission path between the OLT and the splitter in order to extend the optical transmission path over a long distance It has been known.

  Further, a system that can perform wavelength division multiplex communication (WDM) by connecting MUX / DEMUX and an optical repeater to an existing optical transmission system is described in Patent Document 1 below.

In the optical repeater, for both the optical signal transmitted in the upstream direction from the OLT to the ONU and the optical signal transmitted in the reverse downstream direction, the optical signal is converted into an electrical signal by the light receiving element. Processing is performed such that the electrical signal is subjected to 3R processing by the light receiving circuit, and the light emitting element is driven based on the output signal of the light receiving circuit to convert the electrical signal into an optical signal. The 3R processing is equalization amplification (reshaping), identification regeneration (regeneration), and retiming processing.
Japanese Patent Laid-Open No. 2002-261697

  The CATV optical repeater is generally placed outdoors away from the OLT, and the output of the light emitting element in the CATV changes due to the difference in environmental temperature, or the relay becomes impossible due to a power failure, or the optical repeater It is necessary to manage the optical repeater in order to cope with events such as transmission fluctuation abnormality of the power supply unit, housing door opening abnormality, internal temperature rise abnormality, and inundation abnormality.

  For such management, it is necessary to install a management electric circuit in the optical repeater and to connect the management electric circuit to the telecommunication line. However, in order to install a new telecommunications line for managing the optical repeater, a large-scale construction is required and the cost increases. In addition, when there is no room for laying a new telecommunications line, management of the optical repeater must be abandoned.

  On the other hand, optical multiplexing may be possible using an optical signal of a wavelength dedicated for optical repeater management separately from the light of the wavelength normally used in an optical transmission system. A wavelength division multiplexing apparatus is required, and cannot be easily adopted from the viewpoints of cost and space.

  An object of the present invention is to provide an optical transmission system and an optical repeater that can easily introduce a management function for the optical repeater from the viewpoints of cost and work.

  A first aspect of the present invention for solving the above-described problem is that a relay apparatus installed in an optical transmission path between at least one subscriber premises and a center side includes the center of the optical transmission path. An optical signal processing unit connected between the first optical transmission line on the side and the second optical transmission line on the subscriber premises side, an optical multiplexing / demultiplexing unit connected to the optical transmission line, and a management electric An optical repeater having a management optical line terminating device that inputs and outputs signals and is connected to the optical transmission line via the optical multiplexing / demultiplexing unit.

  According to a second aspect of the present invention, in the optical repeater according to the first aspect, the management optical line terminator has a function equivalent to that of the optical line terminator disposed on the subscriber premises side. It is characterized by that.

  According to a third aspect of the present invention, in the optical repeater according to the first or second aspect, the management optical line terminator is configured to connect the first optical transmission line via the optical multiplexing / demultiplexing unit. And either one of the second transmission lines.

  According to a fourth aspect of the present invention, in the optical repeater according to any one of the first to third aspects, an optical signal processing unit is connected to the first optical transmission line on the center side to provide an optical First electrical / optical conversion means for performing conversion and reverse photoelectric conversion; and second electrical / optical conversion means for performing photoelectric conversion and reverse photoelectric conversion connected to the second optical transmission line on the subscriber side And an electric line connected between the first electric / optical converting means and the second electric / optical converting means to transmit an electric signal between them.

  According to a fifth aspect of the present invention, in the optical repeater according to the first to fourth aspects, at least one of the first electric / optical conversion unit and the second electric / optical conversion unit is And a processing circuit for performing processing of amplification, identification reproduction, and retiming.

  According to a sixth aspect of the present invention, there is provided the optical repeater according to any one of the first to fifth aspects, and the optical repeater provided on the center side and connected to the optical repeater via the first optical transmission line. A first optical line terminator, and a second optical line terminator disposed on the subscriber's home side and connected to the repeater via the second optical transmission line. This is an optical transmission system.

  According to a seventh aspect of the present invention, in the optical transmission system according to the sixth aspect, the optical repeater has a third optical transmission between the first optical transmission line and the second optical transmission line. A plurality of connections are made through a road.

  According to the present invention, the management function unit for transmitting the relay device management signal for managing the optical repeater is provided in the optical repeater and is connected to the optical transmission line via the optical line terminator (ONU). Therefore, it is not necessary to install a telecommunication line for managing the optical repeater or to use an optical signal of a wavelength different from that of normal optical transmission, and without affecting the existing operation. An optical repeater management signal can be transmitted to and from the center device.

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

  FIG. 1 is a configuration diagram of a PDS type optical transmission system according to an embodiment of the present invention.

  In FIG. 1, an optical transmission line composed of an optical fiber 2 connected to a center-side optical line terminating device (OLT) 1 such as CATV is connected to a first optical coupler (optical multiplexer / demultiplexer) via an optical repeater 4. ) 5 is connected. The optical transmission lines branched into a plurality by the first optical coupler 5 are optical terminal units (ONUs) 7-1,... At a plurality of subscribers via optical fibers 6-1,. 7-n (n is a natural number). Each of the ONUs 7-1,..., 7-n includes an optical transceiver 8a and an ONU function 8b connected thereto.

  In general, the term ONU includes the function of an optical transceiver. However, in the description of the present invention, the ONU will be described by dividing it into an optical transceiver and an ONU function.

  As OLT1, ONU7-1,... 7-n, GEPON (Gigabit Ethernet (registered trademark) PON) conforming to EFM standard IEEE802.3ah and ITU-T recommendation G. 984. A device that conforms to regulations such as GPON (Gigabit Passive Optical Network) according to x is used.

  The optical repeater 4 includes a first EO / OE section (electrical / optical conversion means) 21 connected to the optical fiber 2 on the OTL 1 side and a second optical transmission line connected to the first optical coupler 5 side. An EO / OE section (electric / optical conversion means) 22 of the first EO / OE section 21, an electric line 23 for transmitting an electric signal between the first EO / OE section 21 and the second EO / OE section 22, and a second EO The optical transmission line connected to the optical input / output end of the / OE unit 22 via the optical waveguide or the optical fiber 19 is branched into at least two systems on the subscriber's home side in the downstream direction, and one system is connected to the subscriber home side. A second optical coupler (optical multiplexer / demultiplexer) 20 connected to the optical fiber 3, and a management ONU 24 optically connected to the second system on the downstream side of the second optical coupler (optical multiplexer / demultiplexer) 20, Various devices such as door open / close sensor, temperature sensor, power supply voltage sensor, alarm, heater, etc. in the optical repeater 4 And a management function for inputting / outputting detection signals and control / setting signals to / from the first and second EO / OE units 21 and 22 and various devices 25. Part 26.

  Downlink is the direction of transmission from the center to the subscriber's house, and uplink is the opposite direction.

  The first and second EO / OE portions 21 and 22 and the electric line 23 that electrically connects them have a configuration as shown in FIG.

  In FIG. 2, an electrical line 23 connecting the first EO / OE unit 21 and the second EO / OE unit 22 includes a first electrical line 23 a that propagates an electrical signal in the upstream direction and an electrical signal in the downstream direction. A second electric line 23b to be propagated is provided.

  The first EO / OE unit 21 converts a first WDM coupler 31 connected to the optical fiber 2 on the OTL1 side and a downstream optical signal received through the first WDM coupler 31 into an electrical signal. 1 light receiving element 32, and a first receiving circuit 33 that outputs the electric signal output from the first light receiving element 32 by performing the 3R or 2R process, and further outputs from the second electric line 23 b. A first drive circuit 44 that outputs a predetermined drive current based on the electrical signal of the optical fiber 2, and light generated by supplying the drive current from the first drive circuit 44 through the first WDM coupler 63. The first light emitting element 45 that outputs to the light source.

  The second EO / OE unit 22 includes a second drive circuit 34 that outputs a predetermined drive current based on a downstream electric signal from the first electric line 23a, and a drive current from the second drive circuit 34. And a second WDM coupler 41 for outputting the light input from the second light emitting element 35 to the optical fiber 19 on the second optical coupler 20 side. Furthermore, a second light receiving element 42 that receives an upstream optical signal propagated from the second optical coupler 20 side through the second WDM coupler 41 and converts it into an electrical signal, and a second light receiving element 42. A second receiving circuit 43 that performs 2R or 3R processing on the output electric signal and outputs the processed electric signal to the second electric line 23b. Note that 2R is a process of identification reproduction and retiming, and 3R is a process obtained by adding equalization amplification to them.

  The management ONU 24 is a device having a protocol specification of the PON interface, and has the same circuit configuration as the ONUs 7-1,..., 7-n on the subscriber premises side, and as shown in FIG. The OUN function unit 24b is electrically connected to the OUN function unit 24b.

  In FIG. 3, an optical transceiver 24 a includes a WDM unit 11 connected to an optical fiber 18 optically coupled to a second WDM coupler 41 via a second optical coupler 20, and one branched by the WDM unit 11. An optical / electrical conversion circuit unit 12 having a light receiving element (not shown) connected to the other optical waveguide and an electric / optical unit having a light emitting element (not shown) connected to the other optical waveguide branched by the WDM unit 11. And a conversion circuit 13.

  The ONU function unit 24b is an electric circuit, and the ONU LSI 31 for PON processing having an input / output unit connected to the optical / electrical conversion circuit unit 12 and the electric / optical conversion circuit 13 includes a 10/100 PHY controller 32, The first LAN interface 35 including the transformer 33 and the RJ25 connector 34, the second LAN interface 39 including the 10/100/1000 PHY controller 36, the transformer 37 and the RJ25 connector 38, the ZBT-RAM 40, and the data bus 41 are connected. Has been. Further, an SRAM 42 and a flash memory 43 are connected to the bus data bus 41, and a program and the like are stored in the flash memory 43. Plugs (not shown) connected to the management signal input / output terminals of the management function unit 25 are inserted into the RJ45 connectors 34 and 38.

  Although not particularly illustrated, device signals such as alarms of various devices 25 may be electrically connected to the GPIO interface in the LSI 31, and the I2C interface in the LSI 31 is connected via an analog / digital conversion board. Of these various devices 25, a temperature sensor or the like may be electrically connected.

  The management function unit 26 inputs state monitoring signals of the first and second EO / OE units 21 and 22 and device signals in the various devices 25, and the first and second EO / OE units 21 and 22. The monitoring / control / setting circuit configuration outputs a signal capable of controlling each device in the various devices 25 and setting conditions.

  In FIG. 1, reference numeral 15 denotes a supervisor connected to the OTL 1, and 16 denotes a monitoring operation device that monitors and operates the optical repeater 4 by inputting and outputting signals to and from the supervisor 15.

  In the optical transmission system having the optical repeater as described above, the 1.3 μm wavelength light transmitted from the ONUs 7-1,..., 7-n at the subscriber's homes through the optical fibers 6-1,. The signals are combined by the first optical coupler 5, transmitted to the optical fiber 3, and input to the optical repeater 4.

  Further, the optical signal input from the subscriber's home side into the optical repeater 4 is combined with the optical signal from the management ONU 24 by the second optical coupler 20, and further, the second EO / The signal is converted into an electric signal in the OE unit 22 and further input to the first EO / OE unit 22 via the electric line 23, where it is converted into an optical signal and output to the optical fiber 2 on the OLT 1 side.

  That is, in FIG. 2, the optical signal input from the optical fiber 19 to the second WDM coupler 41 is converted into an electrical signal by the second light receiving element 42 and further subjected to 2R processing or 3R processing by the second receiving circuit 43. Then, the signal is output to the first drive circuit 44 via the second electric line 23b. Then, the first light emitting element 45 is driven by the driving current output from the first driving circuit 44, and the optical signal in the wavelength band of 1.3 μm output from the first light emitting element 45 is the first WDM coupler 31. Is output to the optical fiber 2 via.

  On the other hand, the optical signal having a wavelength of 1.49 μm output from the OLT 1 propagates through the optical fiber 2 and is input to the first EO / OE unit 21, where it is converted into an electric signal and then passed through the electric line 23. The signal is input to the second EO / OE unit 22 and returned to the optical signal. The optical signal output from the second EO / OE unit 22 is propagated to the optical fiber 19 and the second optical coupler 20.

  That is, in FIG. 2, the optical signal input to the first WDM coupler 31 is converted into an electrical signal by the first light receiving element 32, and further subjected to 3R or 2R processing by the first receiving circuit 33. It is output to the second drive circuit 34 through the electric line 23a. Then, the second light emitting element 35 is driven by the drive current output from the second drive circuit 34, and an optical signal is output to the optical fiber 19 via the second WDM coupler 41.

  The optical signal propagated in the downstream direction from the optical fiber 19 is branched by the second coupler 20, and a part of the optical signal is further branched by the first optical coupler 5 and then the optical fibers 6-1,. 6-n is transmitted to ONUs 7-1,...

  By the way, the management function unit 26 in the optical repeater 4 is an ONU function unit of the management ONU 24 that uses detection signals, abnormality signals, and the like input from the first and second EO / OE units 21 and 22 and various devices 25 as electrical signals. To 24b. The ONU function unit 24b performs processing such as converting the input electrical signal into a predetermined channel, that is, an ONU logical channel corresponding to the management ONU, and outputs the processed signal to the optical transceiver 24a. The optical transceiver 24a converts the electrical signal into an optical signal having a wavelength of 1.3 μm and outputs it to the second optical coupler 20 through a predetermined channel. The predetermined channel is a channel that is not selected by the subscriber's home.

  The optical signal of the predetermined channel input to the optical transceiver 24a is combined with the optical signal transmitted from the subscriber premises by the second optical coupler 20 and transmitted to the second EO / OE unit 22, and further the electric signal. The signal is transmitted to the OLT 1 via the line 23, the first EO / OE unit 21, and the optical fiber 2.

  On the other hand, a management control / setting signal, which is an optical signal of a predetermined channel, output from the OLT 1 via the supervisor 15 from the monitoring operation device 16 is transmitted through the optical fiber 2 at a wavelength of 1.49 μm together with other optical signals. The signal is input to the first EO / OE unit 21, where it is converted into an electric signal, and further input to the second EO / OE unit 22 via the electric line 23, where it is returned to the optical signal. The optical signal output from the second EO / OE unit 22 is branched by the second coupler 20 and output to the management ONU 24 and the first optical coupler 5.

  In the management ONU 24, when the input optical signal is converted into an electrical signal by the optical transceiver 24a and transmitted to the ONU function unit 24b, the ONU function unit 24b manages a predetermined channel of the input signal as a management control / setting signal. To the unit 26.

  Based on the management control / setting signal, the management function unit 26 sets parameters of various devices 25 to predetermined values, or controls the devices of the EO / OE units 21 and 22. Control of the devices of the EO / OE units 21 and 22 includes adjustment of light output power of the light emitting elements 32 and 42, output detection command signals of the light emitting elements 32 and 42, and the like. Also. The parameters of the various devices 25 include, for example, heater temperature setting and alarm sound intensity setting.

  The optical signals are transmitted between the ONUs 7-1,... 7-n and the OTL 1 as usual through the optical repeater 4, and connected to the Internet line or the CATV center device or the like. In this case, in the ONUs 7-1,..., 7-n, optical signals of channels other than a predetermined channel used in the optical signal 24 from the management ONU 24 are selected.

  The system functions in the above optical transmission system are logically shown in FIG. 4, and the management ONU 24 of the optical repeater 4 is a system with the same protocol specifications as the ONUs 7-1,... Therefore, the management ONU 24 can also utilize operations performed between the OTL 1 and the ONUs 7-1,.

  Therefore, the management of the optical repeater 4 installed in the optical transmission line between the OTL 1 and the ONUs 7-1 and 7-n is to use a new separate line for the purpose of extending the distance of the PON optical transmission system. And can be efficiently accommodated in the optical transmission line without affecting the existing operation.

In this case, the second optical coupler 20 provided in the optical repeater 4 needs at least a two-branch structure. Further, the intensity of the optical signal branched by the second optical coupler 20 is larger than that of the second optical coupler 20 in consideration of the difference in transmission distance from the ONUs 7-1,... It is preferable to reduce the power to the management ONU 24 that is the shortest, for example, 10%.
(Second Embodiment)
FIG. 5 is a block diagram showing a configuration of an optical transmission system according to the second embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same elements, and the configuration is the same as that of the first embodiment except for the optical repeater.

  The optical repeater 4 shown in FIG. 5 includes a second optical coupler 20A connected to the optical fiber 2 on the OTL1 side, and a first EO / connected to the first port on the downstream side by the second optical coupler 20. An OE unit (electrical / optical converting unit) 21, a second EO / OE unit (electrical / optical converting unit) 22 connected to the optical fiber 3 on the subscriber's home side, and a first EO / OE unit 21; An electrical line 23 that transmits electrical signals between the second EO / OE units 22, a management ONU 24 that is optically connected to the second port on the downstream side of the second optical coupler 20A, and the optical repeater 4 Connected to the electrical signal input / output terminal of the management ONU 24 and the detection signals and control / setting signals to the first and second EO / OE units 21 and 22 and the various devices 25. And a management function unit 26 for inputting and outputting.

  The first and second EO / OE units 21 and 22 and the electric line 23 connecting them have the configuration as shown in FIG. 2 as in the first embodiment.

  In the optical transmission system having the optical repeater as described above, the optical signal of the wavelength band of 1.3 μm transmitted from the ONUs 7-1,... Is further input to the optical repeater 4 through the optical fibers 3, 6-1, ... 6-n.

  The optical signal input from the subscriber's home side to the optical repeater 4 is input to the second EO / OE unit 22 where it is converted into an electrical signal, and further through the electrical line 23, the first EO / OE. The signal is input to the OE unit 22, converted into an optical signal, and output to the second optical coupler 20A. The second optical coupler 20A combines the optical signal output from the first EO / OE unit 22 and the optical signal of the predetermined channel output from the management ONU 24 and transmits the multiplexed optical signal to the optical fiber 2 on the OLT 1 side. .

  Here, the signal output from the management ONU 24 is based on the optical signal output from the management function unit 26. That is, the management function unit 26 uses the ONU function unit 24b of the management ONU 24 to send detection signals, abnormal signals, and the like input from the first and second EO / OE units 21 and 22 and the various devices 25 constituting the optical repeater 4. Send to. The ONU function unit 24b transmits the input electrical signal to the optical transceiver 24a through a predetermined channel. The optical transceiver 24a converts the electrical signal input from the ONU function unit 24b into an optical signal and outputs the optical signal to the second optical coupler 20A.

  On the other hand, the 1.49 μm wavelength optical signal output from the OLT 1 propagates through the optical fiber 2 and is input to the second optical coupler 20A, where it is branched and connected to the first EO / OE unit 21 for management. It is transmitted to the ONU 24.

  The optical signal input to the first EO / OE unit 21 is converted into an electrical signal here, and then input to the second EO / OE unit 22 via the electrical line 23 to be returned to the optical signal again. The optical signal output from the second EO / OE unit 22 is propagated to the ONUs 7-1 and 7-n at a plurality of subscriber homes via the optical fiber 3 and the first optical coupler 5.

  A management control / setting signal, which is an optical signal of a predetermined channel, output from the monitoring operation device 16 to the OLT 1 via the supervisor 15 is input from the OLT 1 to the second optical coupler 20A via the optical fiber 2. The process branches here and is input to the management ONU 24. The signal output from the OLT 1 may be based on a signal from the network.

  The optical signal input from the second optical coupler 20A to the management ONU 24 is converted into an electrical signal by the optical transceiver 24a, and the ONU function unit 24b converts the signal of a predetermined channel into a management control / setting signal. Is output. Based on the management control / setting signal, the management function unit 26 sets parameters of various devices 25 to predetermined values, or controls the devices of the EO / OE units 21 and 22.

  Therefore, when the system function in the above optical transmission system is logically shown, it is the same as that shown in FIG. 4, and the management ONU 24 of the optical repeater 4 has the same protocol as the ONUs 7-1,. Since the system can be configured according to the specifications, the management ONU 24 can also utilize operations performed between the OTL 1 and the ONUs 7-1,.

  Therefore, the management of the optical repeater 4 installed in the optical transmission line between the OTL 1 and the ONUs 7-1 and 7-n can be performed without using a new separate line for the purpose of extending the distance of the PON optical transmission system. In addition, it is possible to efficiently multiplexly accommodate the optical transmission line without affecting the existing operation.

  The second optical coupler 20A provided in the optical repeater 4 needs at least a two-branch structure. Further, the intensity of the optical signal branched by the second optical coupler 20A is distributed to the EO / OE 21 and the management ONU 24, and the optical transmission distance between the OLT 1 and the optical repeater 4 is secured to the maximum. In consideration of this, if the minimum light reception levels of the EO / OE 21 and the management ONU 24 are equal, the second optical coupler 20A is preferably equally distributed, for example, 50% to 50%.

  When the required optical transmission distance is compared with the embodiment shown in FIG. 1 and the present embodiment shown in FIG. 5, when it is mainly required to increase the transmission distance of the optical fiber 3, 5 which does not require the optical coupler 20 on the output side of the second EO / OE 22 is advantageous, and conversely, it is mainly required to increase the transmission distance of the optical fiber 2. For this purpose, the embodiment shown in FIG. 1 is advantageous.

Further, when the failure shown in FIG. 1 is compared with the present embodiment shown in FIG. 5 on the assumption that the relay device 4 has failed, the failure in which the EO / OEs 21 and 22 in the relay device 4 fail and do not operate. In the embodiment of FIG. 1, the optical signal 18 cannot be transmitted to the OLT 1 side even if the management ONU 24 is operating normally. However, in this embodiment shown in FIG. If the ONU 24 for operation is operating normally, there is an advantage that failure information can be transmitted to the OLT 1 side via the coupler 20A.
(Third embodiment)
FIG. 6 is a diagram showing an optical transmission system according to the third embodiment of the present invention, where the same reference numerals as those in FIG. 1 denote the same elements.

  6, a plurality of relay apparatuses 4-1,..., 4-m having the same structure as the optical relay apparatus 4 shown in FIG. 1 or 5 are provided between the OTL 1 and the optical coupler 5 via the optical fiber 2a. By connecting and increasing the number, it is possible to further increase the distance of optical transmission.

  According to this, it is not necessary to install a separate line for management as in the case where a telecommunication line is provided for managing the optical repeaters 4-1,..., 4-m or an optical interface is provided for management. The ONU function unit 27 for electrical signals makes it possible to multiplex the management signal onto the existing PON optical transmission line.

  The management ONU function 24 in the optical repeaters 4-1 to 4-m is substantially the same as the ONUs 7-1 to 7-n on the subscriber premises side, and FIG. As shown in FIG. 7, the management ONU 24 in the optical repeaters 4-1,..., 4-m is logically configured with the existing PON protocol specifications, so the operations of OTL1, ONU7-1,. Can be used.

  As described above, according to the first to third embodiments, the management ONU 24 is connected to the optical transmission lines 2 and 3 between the OLT 1 and the first optical coupler 5 in the optical repeater 4. Therefore, the optical loss to the management ONU 24 can be minimized (optimized). Therefore, the optical transmission line 2 or the optical transmission line 3 for the main signal can be obtained. It is possible to configure the management ONU 24 while ensuring the maximum allowable optical loss, and to utilize the operation between the existing OLT and the ONU function unit.

  Furthermore, according to the optical transmission system using the optical repeater, it becomes possible to manage the optical repeater 4 with an optical signal having the same wavelength as that of the subscriber's house, and a new optical communication line with a special wavelength can be established. There is no need to install or multiplex with optical signals for subscribers using optical signal processing devices with different wavelengths, and it is possible to easily multiplex connections to PON lines using the PON specification protocol. There is an advantage that the management of the network and the management of the optical repeater can be easily integrated.

FIG. 1 is a configuration diagram of an optical transmission system according to the first embodiment of the present invention. FIG. 2 is a block diagram showing a photoelectric conversion unit of the optical repeater used in the optical transmission system according to the first embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of the management ONU in the optical repeater used in the optical transmission system according to the first embodiment of the present invention. FIG. 4 is a block diagram showing a relationship with the ONU function viewed from the OLT of the optical transmission system according to the first embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of an optical repeater used in the optical transmission system according to the second embodiment of the present invention. FIG. 6 is a block diagram showing a configuration of an optical transmission system according to the third embodiment of the present invention. FIG. 7 is a block diagram showing a relationship with the ONU function viewed from the OLT of the optical transmission system according to the second embodiment of the present invention.

Explanation of symbols

1: OLT
2, 3: optical fibers 4, 4-1, ... 4-m: optical repeater 5: optical couplers 6-1, ... 6-n: optical fibers 7-1, ... 7-n: ONU
20, 20A: Optical coupler 21, 22: EO / OE section 23: Electric line 24: ONU for management
24a: Optical transceiver 24b: ONU function unit 25: Various devices 26: Management function unit

Claims (7)

In a relay device installed in an optical transmission line between at least one subscriber premises and a center,
An optical signal processing unit connected between the first optical transmission line on the center side and the second optical transmission line on the subscriber premises side of the optical transmission line;
An optical multiplexer / demultiplexer connected to the optical transmission line;
An optical repeater comprising: a management optical line terminating device that inputs / outputs a management electrical signal and is connected to the optical transmission line via the optical multiplexing / demultiplexing unit. 2. The optical repeater according to claim 1, wherein the management optical line terminator has a function equivalent to that of an optical line terminator arranged on the subscriber premises side. The management optical line terminator is connected to either the first optical transmission line or the second optical transmission line via the optical multiplexing / demultiplexing unit. The optical repeater according to claim 1 or 2. The optical signal processor
First electrical / optical conversion means connected to the first optical transmission line on the center side for performing photoelectric conversion and reverse photoelectric conversion;
A second electrical / optical conversion means connected to the second optical transmission line on the subscriber side for performing photoelectric conversion and reverse photoelectric conversion;
4. An electric line connected between the first electric / optical converting means and the second electric / optical converting means and transmitting an electric signal between them. The optical repeater according to any one of the above. The at least one of the first electrical / optical conversion unit and the second electrical / optical conversion unit includes a processing circuit for performing equalization amplification, identification reproduction, and retiming processing. The optical repeater according to claim 1. An optical repeater according to any one of claims 1 to 5,
A first optical line terminator provided on the center side and connected to the optical repeater via the first optical transmission line;
An optical transmission system comprising: a second optical line terminating device disposed on the subscriber premises side and connected to the optical repeater via the second optical transmission line. The optical repeater is connected in plural via a third optical transmission line between the first optical transmission line and the second optical transmission line. Optical transmission system.

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