JP3173824B2 - Optical terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical terminal apparatus in an optical transmission system for performing optical transmission between terminal stations each having one or more active apparatuses and one standby apparatus. In such an optical transmission device, the configuration for switching from the active device to the backup device is simplified and flexibility is provided, and the signal switched to the backup device is not out of synchronization at the time of switching. Technology is desired.

[0002]

2. Description of the Related Art FIGS. 15 and 16 show an optical transmission system between a terminal station A and a terminal station B having an optical terminal apparatus proposed by the present applicant in Japanese Patent Application No. 293420/1990. 1 shows a schematic configuration. In the arrangements of FIGS. 15 and 16 (and throughout the following description), the components of terminal A are denoted by the reference numeral "no" and the components of terminal B are denoted by "
The attached reference numerals are added. Further, since the configurations of the terminal station A and the terminal station B are basically the same, the following description will be made only for one terminal station. 15 and 16
, 110 is a standby terminal device (standby device), 11
,... 11N are working terminal devices (working devices), TX is a transmitting unit, RX is a receiving unit, 210, 211,.
.., 21N are one-to-two optical couplers, 311,
, 31N are one-to-two optical couplers,
Or one-to-two optical switch, LPS is a low priority signal, T
S1, TS2, · · · TSN, respectively, the end station (lower-level) signal, L ₀ is the preliminary optical transmission path between end stations, and,
L ₁ , L ₂ ,..., L _N are working optical transmission lines between terminal stations.

As shown in FIGS. 15 and 16, each of the standby device and the working device has two pairs of a transmitting section TX and a receiving section RX, and one pair has a transmission section corresponding to each apparatus. The other pair, when connecting each working device to the protection transmission line, between the working device and the protection device, a two-way optical transmission line indicated by a solid line with an arrow in the figure. Provided for exchanging optical signals via The optical couplers 210, 211,..., 21N connect a transmitting unit and a receiving unit in a pair for exchanging optical signals between the working device and the standby device, respectively, to a bidirectional optical transmission line. It is for. The optical couplers or optical switches 311, 312,... 31N are connected to the spare optical transmission line L ₀ due to a failure of the corresponding optical transmission line.
It is provided for connecting an active device to be connected to a standby device and a standby device. Within the backup unit, to connect the optical transmission path and the protection optical transmission line L ₀ that connects the working apparatus of the end station of the. The optical couplers or optical switches 311, 31 corresponding to each of the optical couplers 210, 211,.
2,... 31N are connected as shown in FIG.

FIGS. 18 and 19 show another optical transmission system between a terminal A and a terminal B having an optical terminal device proposed by the present applicant in Japanese Patent Application No. 293420/1990. 1 shows a schematic configuration. In the configuration of FIGS. 18 and 19, reference numeral 120 denotes a standby terminal device (standby device);
.., 12N are working terminal devices (working devices), 321, 322,.
, 33N are one-to-two optical couplers or one-to-two optical switches, respectively. In the configuration of FIGS. 18 and 19, the optical transmission path is provided for connecting the working unit and the backup unit to be connected to the spare optical transmission line L ₀ is made up of one direction transmission channel pair, For each one-way transmission line, the above-mentioned one-to-two optical coupler, or
A set of one-to-two optical switches 321, 322,... 32N,
, 331, 332,... 33N are provided.

FIGS. 20 and 21 show still another optical transmission between a terminal A and a terminal B equipped with an optical terminal device proposed by the present applicant in Japanese Patent Application No. 293420/1990. 1 shows a schematic configuration of a system. FIG. 20 and FIG.
, 10N are working terminal devices (working devices), and 200, 201,... 20N are each one-to-two. The optical coupler 300 is a one-to-many optical coupler or a one-to-many optical switch. In the configuration of FIGS. 20 and 21, one-to-many optical coupler or a 1-many optical switch 300 is connected to the spare optical transmission line L ₀ from the bidirectional optical transmission line connected to the working device It is provided for selecting a device corresponding to the active device to be connected and connecting to the standby device.

[0006]

However, in recent years,
In each of the above optical terminal devices, the low-order group signal accommodated in each working device, or the low-order group signal accommodated in a plurality of working devices is various (for example, in transmission speed), Of such a variety of low-order group signals, a signal of a desired combination, the flexibility is required to be able to exchange between the opposite terminal via the standby optical transmission line, This is not possible in the configurations of FIGS. 18 to 21 described above.

Further, according to the above configuration, it is difficult to match the clock signals of the active device and the standby device at the bit level, and therefore, when switching from the active device to the standby optical transmission line, the standby system has There is a possibility that frame synchronization loss or the like may occur instantaneously. An object of the present invention is to provide an optical terminal device capable of exchanging a signal of a desired combination among various low-order group signals with an opposite terminal via a standby optical transmission line. As a first object.

A second object of the present invention is to provide an optical terminal device which does not cause frame synchronization loss or the like in the standby system when switching from the active device to the standby optical transmission line.
The purpose of.

[0009]

FIG. 1 shows a basic configuration of a first embodiment of the present invention. In FIG. 1, 1 is a spare transmission means, 2 is a multiplexing / demultiplexing means, 3 ₁ , 3 ₂ ,.
_n is a switching means, 4 ₁ , 4 ₂ ,..., 4 _m is a group of a plurality of working terminal devices, and 5 ₁ , 5 _{2 ,.}
Is a group of a plurality of working terminal devices.

A first aspect of the present invention is a system wherein each
Terminal device 4₁, 4_Two, ... 4_m, 5 ₁, 5_Two, ... 5_rYou
And one spare terminal device 14, the terminals facing each other.
Between the stations, the plurality of working terminal devices 4₁, 4_Two, ... 4_m,
5₁, 5_Two, ... 5_rAs a result, the plurality of working terminal devices
Optical transmission via multiple working optical transmission lines connected to each other
When a failure occurs in any of the working optical transmission lines.
The opposite terminal station via the standby terminal apparatus 14.
Light that performs optical transmission by switching to a standby optical transmission line that connects between
Optical terminal equipment included in each terminal of the transmission system
It has the following features.

The working optical transmission line transmits an optical signal at a transmission speed corresponding to each working optical transmission line among one or more types of first transmission speeds. It said plurality of working terminal unit _{4 1, 4 2, ··· 4} m, 5 1, 5 2, ··· 5 r are each belonging to any of a plurality of groups. The standby terminal device 14 includes a standby transmission unit 1 and a multiplexing / demultiplexing unit 2, and the standby transmission unit 1 performs the first transmission via the standby optical transmission line with the opposite terminal. Optical transmission is performed at a predetermined second transmission rate higher than the transmission rate, and the multiplexing / demultiplexing means 2 inputs and outputs signals at the first transmission rate, respectively, and outputs a plurality of signals provided for the plurality of groups. First
, And a second input / output port connected to the backup transmission means 1 for inputting / outputting the signal of the second transmission rate, and the second input / output port received by the backup transmission means 1 A signal of a transmission rate is separated into a plurality of signals of the first transmission rate and output from the first input / output port, and a plurality of signals having the first transmission rate are output from the first input / output port. Is received and multiplexed, converted into a signal equal to the second transmission rate, and supplied to the spare transmission means 1 from the second input / output port.

The working optical terminal equipment is provided for each of the groups, and is selected from one or a plurality of working terminal equipments 4 ₁ , 4 ₂ ,... 4 _m belonging to each group. 1
A plurality of switching means 3 ₁ , 3 ₂ ,... 3 _n for connecting one working terminal device to a corresponding first input / output port in the multiplexing / demultiplexing means 2 by an optical transmission line. FIG. 2 shows a basic configuration of the second embodiment of the present invention.

In FIG. 2, 1 is a spare transmission means, 2 'is a second multiplexing / demultiplexing means, 6 is a switching connection means, 7 ₁ , 7 ₂ ,
... 7 _s is a plurality of working terminal devices, 8 ₁ , 8 ₂ , ... 8 _s
The low-order side multiplexing and demultiplexing _{means, 9 1, 9 2, ···} 9 s high order side multiplexing and demultiplexing _{means, 10 1, 10 2, ···} 10 s is a pre-side connection means. A second aspect of the invention, each of a plurality of working terminal unit 7 _1, 7 _2, · · · 7 _s and one spare terminal unit 1
Has a 5, between the end stations which face each other, said plurality of working terminal unit 7 _1, 7 _2, by · · · 7 _s, a plurality of working beams are connected to the respective plurality of working terminal unit transmits The optical transmission is performed via a channel, and when a failure occurs in any of the working optical transmission lines, the optical network is switched to a standby optical transmission line connecting the opposed terminal stations via the standby terminal device 15. The present invention relates to an optical terminal device provided in each terminal station of an optical transmission system for performing optical transmission by using the following features.

The working optical transmission line may include one or more types.
Of the first transmission speed of
The optical signal is transmitted at a corresponding transmission speed. The spare optical transmission line
Transmits an optical signal at a second transmission rate. The plurality of current
Terminal equipment 7₁, 7_Two, ... 7_sIs the lower-order multiplexing / demultiplexing hand
Step 8₁, 8 _Two, ... 8_sAnd higher-order multiplexing / demultiplexing means 9₁, 9
_Two, ・ ・ ・ 9_sAnd the spare side connection means 10₁,Ten_Two,···Ten_sWhen
And the lower-order multiplexing / demultiplexing means 8₁, 8_Two, ... 8
_sReceives the low-order group signal and outputs one or more third
Multiplexes to a transmission rate signal, and the one or more
The signal of the third transmission rate is separated and output as a low-order group signal.
Force, higher-order multiplexing / demultiplexing means 9₁, 9_Two, ・ ・ ・ 9_sIs before
Further multiplexing the one or more third transmission rate signals;
The working optical transmission line connected to the working terminal equipment.
Multiplex to 1 transmission rate, and through the working optical transmission line
The first transmission rate signal received by the
A plurality of third transmission rate signals are separated into spare side connection means.
Ten₁,Ten_Two,···Ten_sIs the lower-order multiplexing / demultiplexing means 8₁,
8_Two, ... 8_sThe one or more third
The transmission speed signal is connected to the standby terminal device 15 side.
Switch to

The protection terminal device 15 receives the signal of the second transmission rate received by the protection terminal device, separates the signal into the one or a plurality of signals of the third transmission rate, and outputs the signal. A standby device multiplexing / demultiplexing means 2 'for inputting and multiplexing the plurality of signals of the third transmission rate and outputting the multiplexed signals as the signal of the second transmission speed;
Wherein 1 or the signal of a plurality of third transmission rate is output pre connector means 10 _1, 10 _2, of the terminals of · · · 10 _s, the selected ones, the backup unit multiplexing and demultiplexing A switching connection means 6 is provided for connecting the terminal to which the signal of the one or a plurality of third transmission rates is input / output by the means 2 'to the one corresponding to the transmission rate.

FIG. 3 shows a basic configuration of a third embodiment of the present invention. In FIG. 3, 1 'is a spare transmission means,
11 is a working transmission means, 12 is a protection terminal equipment, 13 is a working terminal equipment, 16 is a switching means, and 17 is a synchronization means. According to a third aspect of the present invention, each of the above-mentioned one or more working terminal devices includes one or more working terminal devices 13 and one spare terminal device 12, and 13, by performing optical transmission through a plurality of working optical transmission lines connected to the plurality of working terminal devices, and when a failure occurs in any of the working optical transmission lines, The present invention relates to an optical terminal apparatus provided in each terminal station of an optical transmission system that performs optical transmission by switching to a standby optical transmission path connecting the opposite terminal stations via the apparatus 12, and has the following features. .

Each of the working optical terminal devices 13 includes a working transmission means 11 for performing optical transmission via a working optical transmission line connected to each working optical terminal device, and a transmission device via the working optical transmission line. Switching means 16 for switching an optical signal to be connected to the standby terminal device side.

The protection terminal device 12 transmits a signal to be transmitted by the protection terminal device 1 'for performing synchronous optical transmission via the protection optical transmission line and a signal to be transmitted by the working terminal device connected by the switching device 16. A synchronization unit 17 for synchronizing with the internal clock of the standby terminal device 12 is provided.

[0019]

According to the first aspect of the present invention, one of the plurality of working terminal devices belonging to each group is selected.
One of the signals to be transmitted to the opposite station is the switching means 3 ₁ ,
3 ₂ is connected to the preparatory terminal unit by · · · 3 _n. Therefore, signals from these multiple groups are multiplexed
The multiplexed signal is multiplexed by the demultiplexing means 2 and transmitted to the opposite station via the standby optical transmission line by the standby transmission means 1. , And transmitted to the selected working terminal device via the corresponding group switching means 3 ₁ , 3 ₂ ,... 3 _n . Therefore, as compared with the conventional configuration, there is an advantage that a single protection terminal device can simultaneously function as a protection device for a plurality of working terminal devices.

According to the second embodiment of the present invention, the plurality of working terminal devices 7 ₁ , 7 ₂ ,..., 7 _s have lower-order side multiplexing / demultiplexing means 8 ₁ , 8 ₂ ,. The one or a plurality of signals of the third transmission rate multiplexed by 8 _s are all switched and connected via the spare connection means 10 ₁ , 10 ₂ ,... 10 _s of the respective working terminal devices. Applied to means 6. The switching connection means 6 supplies the selected signal to the standby apparatus multiplexing / demultiplexing means 2 '. The protection device multiplexing / demultiplexing means 2 'of the protection terminal equipment multiplexes the plurality of selected signals and transmits the multiplexed signals to the opposite station via the protection optical transmission line by the protection transmission means 1. Also, the signal transmitted from the opposite station is received by the standby transmission means 1 and the standby device multiplexing / multiplexing is performed.
After being separated by the separating means 2 'into the signal of the second transmission rate, the signal is supplied by the switching connecting means 6 to the protection side connecting means of the working terminal equipment corresponding to the selected signal. In this case, the transmission speeds of the signals connected from each working terminal device to the protection terminal device by the switching connection means 6 are not the same as each other, but are equal to the transmission speeds of the signals accommodated by the protection device multiplexing / demultiplexing means 2 '. If they are equal (if correspondence is given), it is good. In this way, a single protection terminal device can simultaneously function as a protection device for a plurality of working terminal devices, and the flexibility with respect to the combination of signals of the working terminal devices transmitted simultaneously by the protection terminal devices is increased. growing.

According to the third aspect of the present invention, in a working terminal device in which a failure has occurred in a corresponding working optical transmission line,
The switching means 16 switches an optical signal to be transmitted via the working optical transmission line so that the optical signal is connected to the standby terminal device side. The switched signal is synchronized with the internal clock of the protection terminal device 12 by the synchronization means 17 before being supplied to the protection transmission means 1 'for performing synchronous optical transmission via the protection optical transmission line. When switching from the device to the spare optical transmission line, frame synchronization in the spare system does not occur.

[0022]

FIG. 4 shows the structure of a first embodiment of the present invention.
Things. In FIG. 4, 130 is a standby optical terminal device,
131 ... 13N are working optical terminal equipments, 600 and 60
1,... 604, 605,.
Unit, 621 is a switch unit, 622 is a higher-order side multiplexing / demultiplexing unit
623 is a low-order group signal interface and multiplex
Separating part, L₀Is a spare optical transmission line between the terminal stations, and L₁,
L _Two, ... L_NIs the working optical transmission line between the terminal stations, C1,.
C8 is an optical coupler or an optical switch. The present invention
The first embodiment is configured to realize the first embodiment of the present invention.
This is an example of the configuration. In the first embodiment of the present invention,
Since the configurations at the stations A and B are the same,
In the following, only the configuration of the terminal station A will be described.

The transmitting / receiving unit 6 in each of the protection optical terminal device 130 and the working optical terminal devices 131... 13N.
., 619 are a spare optical transmission line L ₀ connected to each device and a working optical transmission line L ₁ ,
L ₂ ,... Are transmission / reception units for transmitting / receiving optical signals to / from the terminal station B opposed via L _N. Other transmitting / receiving units 601,... 604, and 606, 60
Reference numerals 8, 610, 612, 614, 616, 618, and 620 are provided in the terminal station A for connecting the working optical terminal apparatus and the standby optical terminal apparatus by an optical transmission line. is there. Transmission / reception unit 6 of standby optical terminal apparatus 130
01,... 604 each have a pair of one-way optical couplers or optical switches C1 and C2,.
8, two working optical terminal equipments are connected to each other.

When C1, C3,... C7 (transmitting an optical signal in the direction of the standby optical terminal device) are optical switches, each of the working optical terminal devices is connected to the standby optical terminal device. An optical signal to be transmitted to the opposing terminal station B is always output from the transmitting / receiving section (regardless of the normal or abnormal state of the corresponding optical transmission line), and the transmitting / receiving section 610 of the standby optical terminal apparatus.
.. the optical switch connected to each of the optical switches is at most one of a plurality of active optical terminal devices connected to the optical switch.
Control is performed so that only one optical signal is transmitted to the standby optical terminal equipment. In FIG. 4, each optical switch and
As will be described later, a control unit for controlling the switches in the standby optical terminal device and the working optical terminal devices is provided for each of the terminal stations A and B, though not shown.

When C1, C3,... C7 are optical couplers, optical signals from at most one of a plurality of working optical terminal devices connected to the optical coupler are transmitted to the standby optical terminal device. Transmission / reception units (particularly, transmission units) in each working optical terminal device so that they are transmitted (so that optical signals from two working optical terminal devices are not simultaneously input to one optical coupler).
Is controlled.

An E / O conversion circuit (conversion of an electric signal to an optical signal) included in the transmission unit of the transmission / reception unit includes an automatic power control circuit (APC circuit), and is turned on from an OFF state.
Since it takes time to start up (response) when switching to the state, there is a risk of data loss when switching from the OFF state to the ON state.
More preferably, 7 (for transmitting an optical signal in the direction of the standby optical terminal device) is an optical switch.

When C2, C4,... C8 (for transmitting an optical signal from the protection optical terminal equipment to the working optical terminal equipment) are optical switches, the transmission of the protection optical terminal equipment is performed. The optical switch connected to each of the receiving units 610... 604 transmits the optical signal from the standby optical terminal device to at most one of the plurality of working optical terminal devices connected to the optical switch. I do.

When C2, C4,... C8 are optical couplers, the transmitting / receiving sections 610,.
The optical coupler connected to each of the optical transmitters 04 transmits the optical signal from the standby optical terminal to all of the plurality of working optical terminal devices connected to the optical coupler. The O / E conversion circuit (converting an optical signal into an electric signal) included in the reception unit of the transmission / reception unit includes an automatic gain control circuit (AGC circuit).
C2, C4,..., And C8 are light because there is a risk of data loss when switching from the input OFF state to the input ON state because a rise (response) when switching from the FF state to the input ON state takes time. More preferably, it is a coupler.

In the configuration of FIG. 4, the transmission speeds of the plurality of transmission / reception units 601 to 604 of the standby optical terminal may be different from each other. FIG.
2 shows a configuration example of each working optical terminal device in the above configuration. In the configuration of FIG. 5, 161 is a low-order group interface, 162 is a multiplexing / demultiplexing unit, 163 is a switch unit,
164 is a transmitting unit that transmits an optical signal to the working optical transmission line connected to the working optical terminal device, 165 is a receiving unit that receives an optical signal from the working optical transmission line connected to the working optical terminal device, Reference numeral 166 denotes a transmitting unit for transmitting an optical signal to the standby optical terminal, and 167 denotes a receiving unit for receiving an optical signal from the standby optical terminal.

The low-order group signal interface receives the low-order group signal TSi (i = 1 to 8) from the low-order group transmission line and supplies it to the multiplexing / demultiplexing unit 162, which separates the signals. The low-order group signal is sent out onto the low-order group transmission path. The multiplexing / demultiplexing unit 162 multiplexes the low-order group signals and switches the signals.
63, and separates the signal received from the switch unit 163 into a low-order group signal.
61.

FIGS. 6 and 7 show the switch section 16 of FIG.
3 shows a configuration example. In FIG. 6, switches 168 and 169 for electric signals are shown in FIG.
The input / output of the multiplexing / demultiplexing unit 162 is transmitted to the transmitting / receiving unit 164.
And 165, or the transmission / reception units 166 and 167
To either one of Also, in FIG.
Is a switch for an electric signal, and the receiving unit 165
Alternatively, one of the outputs of the receiving unit 167 is multiplexed in FIG.
Connect to the input of separation unit 162. In the configuration of FIG. 7, the output from the multiplexing / demultiplexing unit 162 is always
64 and 166.

The configuration of the protection optical terminal device 130 in FIG. 4 also differs from the above-mentioned working optical terminal device in the configuration of the switch section.
In response to the provision of a plurality of transmission / reception units for performing optical transmission with the working optical terminal equipment, multiplexing /
There are a plurality of higher-order input / output signals of the separation unit 623.
Therefore, the transmission / reception unit 600 corresponding to the standby optical transmission line L ₀
Except that a higher-order multiplexing / separating unit 622 is provided between the lower-order group-side multiplexing / separating unit 623,
This is realized by a configuration similar to the configuration of FIG.

FIG. 8 shows the configuration of the switch unit 621 in the standby optical terminal unit 130. In FIG. 8,
It is omitted to show the configuration of a plurality of transmission / reception units for performing the optical transmission from the low-order side multiplexing / demultiplexing unit 623 to the plurality of pairs of high-order side input / outputs and the working optical terminal equipment. Thus, one pair of input / output of the plurality of pairs of higher-order inputs / outputs from the lower-order multiplexing / separating unit 623 and one pair of input / outputs of the plurality of pairs of inputs / outputs of the higher-order multiplexing / separating unit 622 described above. One of a plurality of transmission / reception units (the transmission / reception units 164 to 164 in FIG. 5) for performing input / output of the data and optical transmission to / from the working optical terminal equipment.
167) (corresponding to 167), only the connection between a pair of input / output signals to be input / output is shown, but in actuality, four configurations of FIG. 8 exist in parallel. In FIG. 8, one of the four pairs of inputs and outputs on the lower side of the higher-order multiplexing / demultiplexing unit 622 is one.
Reference numerals 64 'and 165' denote input / output of one of a plurality of transmission / reception units (for example, transmission / reception unit 601) 166 'and 167 for performing optical transmission with the working optical terminal equipment. '. With the configuration of FIG. 8, for example,
One of lower-order outputs 165 'of higher-order multiplexing / demultiplexing section 622
Is always one input (DM) of the lower-order multiplexing / demultiplexing unit 623.
X) as well as to the transmission section 166 '. The signal received from the working optical terminal unit by the receiving unit 167 ′ is transmitted to one of the lower-order inputs of the higher-order multiplexing / demultiplexing unit 622 under the control of the switch 170.
4 connected to the 'can be transmitted to the terminal station B which is opposed via the protection optical transmission line L _0.

FIG. 9 shows the configuration of the second embodiment of the present invention. In the configuration of FIG. 9, the working optical terminal device also has one or a plurality of transmission / reception units for transmitting an optical signal to / from the standby optical terminal device. In the configuration of FIG. 9, the standby optical terminal device has the same configuration as that of FIG. 4, and has a plurality of transmission / reception units for transmitting optical signals to and from the standby optical terminal device. The optical terminal equipment, like the standby optical terminal equipment, has a lower-order side (for example,
638) and a multiplexing / demultiplexing unit on the higher-order side (for example, 637), and a switch unit (for example, 636) between them. This switch section is realized by a configuration in which the configurations of FIG. 6 or FIG. 7 are arranged in parallel and the number of transmission / reception sections for transmitting an optical signal to / from the standby optical terminal device is arranged. You. In FIG. 9, 1
14N are working optical terminal devices, and reference numerals 700, 630, 640, 650, and 6 are working optical terminal devices.
Reference numeral 60 denotes a transmitting unit, 701, 631, 641, 651, and 661 denote receiving units, 702,.
635, 642, 643, 652 and 662 are transmission / reception units, 706, 636, 646, 656 and
666 is a switch unit, 708, 638, 648, 65
8, and, 668 low-order group signal interface and multiplexing and demultiplexing section, 707,637,647,657, and, 667 higher side multiplexing and demultiplexing unit, 723, L ₀ is the preliminary optical transmission path between end stations , And L ₁ , L ₂ ,..., L _N
.. C8 'are optical couplers or optical switches. The second embodiment of the present invention is an example of a configuration for realizing the above-described second embodiment of the present invention. In the second embodiment of the present invention, since the configurations of the terminal station A and the terminal station B are the same,
Only the configuration of the terminal station A will be described.

The transmitting / receiving unit 7 in each of the standby optical terminal unit 140 and the working optical terminal units 141... 14N.
00 and 701, 630 and 631, 640 and 641, 650 and 651, and 660 and 6
61, preliminary optical transmission line L ₀ is connected to a respective device, and the working optical transmission lines L _1, L _2, transmission of optical signals between the terminal station B to face each other with a · · · L _N A transmission / reception unit that performs reception. Other transmission / reception units 702
... 705, 632 to 635, 642, 643, 65
Reference numerals 2 and 662 are provided for connecting the working optical terminal device and the standby optical terminal device in the terminal station A by an optical transmission line. Each of the transmission / reception units 702,... 705 of the standby optical terminal device 140 has a pair of one-way optical couplers or optical switches C1 'and C2',.
Two transmission / reception units of the working optical terminal equipment are connected via C7 'and C8', respectively.

In the configuration of FIG. 9, the transmission speeds of the plurality of transmission / reception units 702 to 705 of the standby optical terminal may be different from each other. That is, in the configuration of FIG. 9, a signal different transmission speeds of the working optical terminal device transmits, via the protection optical transmission line L ₀ is switched to multiple simultaneous parallel in the transmission rate of the backup optical terminal equipment To the opposite terminal station B.

In the configuration shown in FIGS. 4 and 9, if a plurality of transmission / reception units of the same working optical terminal unit can be connected to a plurality of transmission / reception units of the standby optical terminal unit, FIG.
, The wavelength division multiplexing devices 251 and 253 and the wavelength division demultiplexing devices 250 and 254 are divided into a plurality of transmission / reception units of the standby optical terminal device and a plurality of transmission / reception units of the working optical terminal device. And can be transmitted via a single optical fiber as wavelength division multiplexed optical signals (multiplexed optical signals having different wavelengths).

When a plurality of transmitting / receiving sections of the same working optical terminal apparatus can be connected to a plurality of transmitting / receiving sections of the standby optical terminal apparatus, as shown in FIG. Alternatively, they can be connected by a ribbon fiber formed by bundling a plurality of optical fibers. In the configurations of FIG. 4 and FIG. 9, connected to each transmitting / receiving unit of the standby optical terminal device is at most two working optical terminal devices or transmitting / receiving units in the working optical terminal device. However, in general, when a large number of working optical terminal devices or transmitting / receiving units in the working optical terminal device are connected to each transmitting / receiving unit of the standby optical terminal device, a plurality of corresponding optical Using a coupler or an optical switch, or an optical coupler or an optical switch formed by connecting a plurality of optical couplers or optical switches in a tree shape as shown in FIG. A large number of working optical terminal devices or transmitting / receiving units in the working optical terminal devices can be connected to the receiving unit.

FIG. 13 shows the configuration of the third embodiment of the present invention. The third embodiment of the present invention realizes the above-described third embodiment of the present invention. The configuration in FIG. 13 shows one configuration (as a representative) of the standby optical terminal device and the working optical terminal device among the configurations in the terminal station. In FIG. 13, reference numeral 150 denotes a standby optical terminal unit,
Is an active optical terminal unit, and 351 and 352 are optical couplers or optical switches. In addition, 720 and 730 are low-order group signal interfaces and multiplexing / demultiplexing units, and 721
And 731 are switch units, 722, 724, 732,
734 multiplexing unit, 723,725,733,735 separation unit, 726 transmission unit for transmitting the optical signal to the spare optical transmission line L _0, 727 receiving unit that receives an optical signal from the auxiliary optical transmission line L _0, 728 and 729 are transmission / reception devices for transmitting optical signals between the protection optical terminal equipment and the working optical terminal equipment.
Receiving unit, 736 transmission unit for transmitting the optical signal to the working optical transmission path L _i, 737 receiving unit that receives an optical signal from a working optical terminal apparatus _i, 738 and 739 are spare optical end at the working optical terminal equipment It is a transmission / reception unit for transmitting an optical signal to / from a station device.

Multiplexing units 722 and 73 in the configuration of FIG.
2 and 734 each have a built-in configuration for synchronizing signals to be multiplexed with their own internal clocks.
One example of this configuration is shown in FIG. 14, 600 is a clock generator, 620 is a justification circuit, 630 is a multiplexing circuit, and 611 to 61.
n is a buffer (FIFO) memory. A plurality of signals to be multiplexed are written to the memories 611 to 61n via a signal line 640 at the timing of a write clock (each reception clock). The data written in the memory is read out cyclically at the timing of the read clock (clock synchronized with the clock generated by the clock generator 600) and supplied to the multiplexing circuit 630.
Here, the signals are multiplexed and output from the signal line 650. The justification control circuit 620 supplies the write clock and the read clock to the memory. The clock generated by the clock generator 600 has a frequency slightly higher than the frequency of the above-mentioned received clock. However, in order to prevent the same bit data from being read twice from the memory, the justification control circuit is used. 620 monitors whether the phase of the read clock is a phase timing for reading twice with respect to the phase of the write clock, and when the timing for reading twice is reached, removes one pulse of the read clock. Thus, a plurality of signals input to the multiplexing circuit 630 are multiplexed while being synchronized with the internal clock.

[0041]

As described above, according to the first and second embodiments of the present invention, a signal of a desired combination among a variety of low-order group signals is opposed via a spare optical transmission line. Enables communication with terminal stations. According to the third embodiment of the present invention, when switching from the active device to the standby optical transmission line, frame synchronization in the standby system can be prevented from being lost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a basic configuration of a second embodiment of the present invention.

FIG. 3 is a diagram showing a basic configuration of a third embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

5 is a diagram illustrating a configuration example of each working optical terminal device in the configuration of FIG. 4;

FIG. 6 is a diagram illustrating a configuration of a switch unit 163 in FIG. 5;

FIG. 7 is a diagram illustrating a configuration of a switch unit 163 in FIG. 5;

8 is a diagram illustrating a configuration of a switch unit 621 in the standby optical terminal device 130. FIG.

FIG. 9 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 10 is a diagram illustrating a configuration example for transmitting an optical signal subjected to a wavelength division multiplexing circuit between a standby optical terminal device and a working optical terminal device.

FIG. 11 is a diagram showing a configuration example of a one-to-many coupler used in a modification of the first and second embodiments of the present invention.

FIG. 12 is a diagram showing a configuration of a ribbon fiber.

FIG. 13 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 14 is a diagram showing a configuration example for synchronization in the configuration of FIG. 13;

FIG. 15 is a diagram illustrating a schematic configuration of another optical transmission system between the terminal station A and the terminal station B including the optical terminal apparatus, which has been disclosed by the present applicant.

FIG. 16 is a diagram showing a schematic configuration of another optical transmission system between a terminal station A and a terminal station B having an optical terminal apparatus disclosed by the present applicant.

FIG. 17 is a diagram showing an optical coupler and a transmission route of an optical signal between the optical coupler or the optical switch in the configurations of FIGS. 15 and 16;

FIG. 18 is a diagram illustrating a schematic configuration of another optical transmission system between a terminal station A and a terminal station B including an optical terminal apparatus disclosed by the present applicant.

FIG. 19 is a diagram showing a schematic configuration of another optical transmission system between a terminal station A and a terminal station B having an optical terminal apparatus disclosed by the present applicant.

FIG. 20 is a diagram showing a schematic configuration of another optical transmission system between a terminal station A and a terminal station B having an optical terminal apparatus disclosed by the present applicant.

FIG. 21 is a diagram showing a schematic configuration of another optical transmission system between a terminal station A and a terminal station B having an optical terminal apparatus disclosed by the present applicant.

[Explanation of symbols]

130 ... standby optical terminal equipment 131 ... 13N ... working optical terminal equipment 600,601, ... 604,605, ... 620
.., Transmission / reception section 621 switch section 622 high-order side multiplexing / demultiplexing section 623 low-order group signal interface and multiplexing / demultiplexing section L ₀ … standby optical transmission lines L ₁ , L ₂ ,. _LN : working optical transmission line between terminal stations C1,... C8: optical coupler or optical switch 161: low-order group interface 162: multiplexing / demultiplexing unit 163: switch unit 164: connected to the working optical terminal device A transmitting unit 165 for transmitting an optical signal to the working optical transmission line; a receiving unit 166 for receiving an optical signal from the working optical transmission line connected to the working optical terminal device; 166 transmitting an optical signal to the standby optical terminal device 167: a receiving unit for receiving an optical signal from a standby optical terminal device 140: a standby optical terminal device 141 ... 14N: a working optical terminal device 700, 630, 640, 650, and 660 … Transmission unit 701, 631, 641, 651, and 661 ... Receiving unit 702 ... 705, 632-635, 642, 64
3, 652, and 662: transmission / reception units 706, 636, 646, 656, and 666: switch units 708, 638, 648, 658, and 668: low-order group signal interface and multiplexing / demultiplexing units 707, 637 , 647, 657, and 667... Higher-order side multiplexing / demultiplexing unit L ₀ ... Standby optical transmission line between terminal stations L ₁ , L ₂ ,... L _N. .. C8 ′ optical coupler or optical switch 150 standby optical terminal equipment 151 working optical terminal equipment 351 and 352 optical coupler or optical switch 720 and 730 low-order group signal interface and multiplexing / demultiplexing unit 721 731 ... switching unit 722,724,732,734 ... multiplexing unit 723,725,733,735 ... separating portion 726 ... spare optical transmission line L ₀ ... light Transmission and for transmitting optical signals between the current optical terminal station in the receiving section 728 and 729 ... spare optical terminal device for receiving an optical signal from the transmitting unit 727 ... spare optical transmission line L ₀ to delivering No. receiving unit 736 ... and the backup optical terminal equipment in the working optical transmission path L _i receiving unit 738 and 739 ... working optical terminal device for receiving an optical signal from the transmitting unit 737 ... working optical terminal apparatus _i for transmitting the optical signal to A transmission / reception unit 600 for transmitting an optical signal among them 600 clock generator 620 justification circuit 630 multiplexing circuit 611-61n buffer (FIFO) memory

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/74 H04B 10/02

Claims (5)

(57) [Claims] 1. Each of a plurality of working terminal devices (4 ₁ , 4 ₂ ,
4 _m , 5 ₁ , 5 ₂ ,... 5 _r ) and one standby terminal device (14), and the plurality of working terminal devices (4 _{1) , 4 2, ··· 4 m,} 5 1, 5 2, ·
.. _5r ) performs optical transmission through a plurality of working optical transmission lines connected to the plurality of working terminal devices,
When a failure occurs in any of the working optical transmission lines, an optical transmission for performing optical transmission by switching to a standby optical transmission line connecting the opposed terminal stations via the standby terminal device (14). In the optical terminal device provided in each terminal station of the system, the working optical transmission line transmits an optical signal at a transmission speed corresponding to each working optical transmission line among one or a plurality of types of first transmission speeds. Transmitting the plurality of working terminal devices (4 ₁ , 4 ₂ ,..., 4 _m , 5 ₁ , 5
_2, · · · 5 _r), respectively belonging to any of a plurality of groups, the preparatory terminal unit (14), the first through the preliminary optical transmission path between the terminal stations to the opposite A spare transmission means (1) for performing optical transmission at a predetermined second transmission rate higher than the transmission rate; and a plurality of signals provided at the plurality of groups, respectively, for inputting and outputting signals at the first transmission rate. A first input / output port, and a second input / output port connected to the standby transmission means (1) for inputting / outputting a signal at the second transmission rate, wherein the standby transmission means (1) The signal of the second transmission rate received by the first input / output port is separated into a plurality of signals of the first transmission rate and output from the first input / output port. Receiving and multiplexing a plurality of signals having a transmission rate and equalizing the second transmission rate; Multiplexing / demultiplexing means (2) for converting the signal into a signal and supplying the signal from the second input / output port to the protection transmission means (1), wherein the working optical terminal equipment is provided for each group, One or more working terminal devices (4 ₁ ,
4 _2, · · · 4 _m) of the said multiplexing and demultiplexing means by an optical transmission line of any one working terminal unit that has been selected (2)
3. The optical terminal device according to claim 1, further comprising a plurality of switching means (3 ₁ , 3 ₂ ,... 3 _n ) connected to the corresponding first input / output port. 2. Each of the plurality of working terminal devices (7 ₁ , 7 ₂ ,
.. 7 _s ) and one standby terminal device (15), and between the opposing terminals, the plurality of working terminal devices (7 ₁ , 7 ₂ ,... 7 _s ) Optical transmission is performed through a plurality of working optical transmission lines connected to the plurality of working terminal devices, respectively. When a failure occurs in any of the working optical transmission lines, the protection terminal device (15) ), An optical terminal device provided in each terminal station of an optical transmission system that performs optical transmission by switching to a standby optical transmission line that connects the opposing terminal stations via: Transmitting an optical signal at a transmission rate corresponding to each of the working optical transmission paths among the first transmission rates of the type, the spare optical transmission path transmits an optical signal at a second transmission rate; the working terminal unit _{(7 1, 7 2, ···} 7 s) are each 1 or multiple enter the low order group signals Multiplexes up to the third transmission rate of the signal, and, the one or more third
Multiplexing / separating means (8 ₁ , 8 ₂ ,..., 8 _s ) for demultiplexing a signal having a transmission rate of ₁ and outputting it as a low-order group signal; Are further multiplexed up to the first transmission rate of the working optical transmission line connected to the working terminal equipment, and the signal of the first transmission rate received via the working optical transmission line is Multiplexing the higher-order side multiplexing signal into one or a plurality of signals of the third transmission rate.
Separating means _{(9 1, 9 2, ···} 9 s) and the low-order side multiplexing and demultiplexing means _{(8 1, 8 2, ···} 8 s) the one or more third input and output to The transmission speed signal is
The preliminary connector means _{(10 1, 10 2, ···} 10 s) for switching to connect the side of the preparatory terminal unit (15) and having a, the preparatory terminal unit (15), said preliminary The terminal device receives the signal at the second transmission rate, separates the signal into the one or more signals at the third transmission rate, outputs the signal, and receives the signals at the third transmission rate. Multiplexing and demultiplexing means for outputting a signal of the second transmission rate as a signal at the second transmission rate.
_{Alternatively,} of the terminals of the spare side connection means (10 ₁ , 10 ₂ ,..., 10 _s ) to which a plurality of signals of the third transmission rate are input / output,
A switching unit that connects the selected one to a terminal to which the one or a plurality of signals of the third transmission rate is input / output by the standby device multiplexing / demultiplexing means (2 '), the one corresponding to the transmission rate respectively; An optical terminal device comprising connection means (6). 3. Each of the plurality of working terminal devices (7 ₁ , 7 ₂ ,
.. 7 _s ) and one standby terminal device (15), and between the opposing terminals, the plurality of working terminal devices (7 ₁ , 7 ₂ ,... 7 _s ) Optical transmission is performed through a plurality of working optical transmission lines connected to the plurality of working terminal devices, respectively. When a failure occurs in any of the working optical transmission lines, the protection terminal device (15) ), An optical terminal device provided in each terminal station of an optical transmission system that performs optical transmission by switching to a standby optical transmission line that connects the opposing terminal stations via: Transmitting an optical signal at a transmission rate corresponding to each of the working optical transmission paths among the first transmission rates of the type, the spare optical transmission path transmits an optical signal at a second transmission rate; the working terminal unit _{(7 1, 7 2, ···} 7 s) at least one of the inputs the low-order group signal Multiplexes up to each one or a plurality of third transmission rate of the signal, and, the one or more third
Multiplexing / separating means (8 ₁ , 8 ₂ ,..., 8 _s ) for demultiplexing a signal having a transmission rate of ₁ and outputting it as a low-order group signal; Are further multiplexed up to the first transmission rate of the working optical transmission line connected to the working terminal equipment, and the signal of the first transmission rate received via the working optical transmission line is Multiplexing the higher-order side multiplexing signal into one or a plurality of signals of the third transmission rate.
Separating means _{(9 1, 9 2, ···} 9 s) and the low-order side multiplexing and demultiplexing means _{(8 1, 8 2, ···} 8 s) the one or more third input and output to The transmission speed signal is
The preliminary connector means _{(10 1, 10 2, ···} 10 s) for switching to connect the side of the preparatory terminal unit (15) and having a, the preparatory terminal unit (15), said preliminary The terminal device receives the signal at the second transmission rate, separates the signal into the one or more signals at the third transmission rate, outputs the signal, and receives the signals at the third transmission rate. Multiplexing and demultiplexing means for outputting a signal of the second transmission rate as a signal at the second transmission rate.
_{Alternatively} , terminals of the spare side connection means (10 ₁ , 10 ₂ ,..., 10 _s ) to which a plurality of signals of the third transmission rate are input / output are connected by the spare apparatus multiplexing / demultiplexing means (2 ′). Connecting means (6) for connecting to one of a plurality of terminals for inputting / outputting the signal of the third or third transmission rate, respectively, corresponding to the transmission rate, wherein the spare side connection means (10 ₁ , 10 ₂₎ ,... 10 _s ) a terminal for inputting and outputting the signal of the one or more third transmission rates,
And the first device of the standby device multiplexing / demultiplexing means (2 ').
Alternatively, wavelength division multiplexing / demultiplexing means (2) for wavelength division multiplexing / demultiplexing the one or plurality of third transmission rate signals to terminals to which a plurality of third transmission rate signals are input / output, respectively.
50, 251, 253, 254), and the wavelength division multiplexing / demultiplexing means (250, 251, 253, 254) transmits the wavelength division multiplexed optical signal through a single optical transmission line. An optical terminal device. 4. Each of the plurality of working terminal devices (7 ₁ , 7 ₂ ,
.. 7 _s ) and one standby terminal device (15), and between the opposing terminals, the plurality of working terminal devices (7 ₁ , 7 ₂ ,... 7 _s ) Optical transmission is performed through a plurality of working optical transmission lines connected to the plurality of working terminal devices, respectively. When a failure occurs in any of the working optical transmission lines, the protection terminal device (15) ), An optical terminal device provided in each terminal station of an optical transmission system that performs optical transmission by switching to a standby optical transmission line that connects the opposing terminal stations via: Transmitting an optical signal at a transmission rate corresponding to each of the working optical transmission paths among the first transmission rates of the type, the spare optical transmission path transmits an optical signal at a second transmission rate; the working terminal unit _{(7 1, 7 2, ···} 7 s) at least one of the inputs the low-order group signal Multiplexes up to each one or a plurality of third transmission rate of the signal, and, the one or more third
Multiplexing / separating means (8 ₁ , 8 ₂ ,..., 8 _s ) for demultiplexing a signal having a transmission rate of ₁ and outputting it as a low-order group signal; Are further multiplexed up to the first transmission rate of the working optical transmission line connected to the working terminal equipment, and the signal of the first transmission rate received via the working optical transmission line is Multiplexing the higher-order side multiplexing signal into one or a plurality of signals of the third transmission rate.
Separating means _{(9 1, 9 2, ···} 9 s) and the low-order side multiplexing and demultiplexing means _{(8 1, 8 2, ···} 8 s) the one or more third input and output to The transmission speed signal is
The preliminary connector means _{(10 1, 10 2, ···} 10 s) for switching to connect the side of the preparatory terminal unit (15) and having a, the preparatory terminal unit (15), said preliminary The terminal device receives the signal at the second transmission rate, separates the signal into the one or more signals at the third transmission rate, outputs the signal, and receives the signals at the third transmission rate. Multiplexing and demultiplexing means for outputting a signal of the second transmission rate as a signal at the second transmission rate.
_{Alternatively} , terminals of the spare side connection means (10 ₁ , 10 ₂ ,..., 10 _s ) to which a plurality of signals of the third transmission rate are input / output are connected by the spare apparatus multiplexing / demultiplexing means (2 ′). Connecting means (6) for connecting to one of a plurality of terminals for inputting / outputting the signal of the third or third transmission rate, respectively, corresponding to the transmission rate, wherein the spare side connection means (10 ₁ , 10 ₂₎ ,... 10 _s ) a terminal through which the signal of the one or more third transmission rates is input / output;
And the first device of the standby device multiplexing / demultiplexing means (2 ').
Alternatively, an optical terminal apparatus characterized in that terminals for inputting and outputting a plurality of signals of a third transmission rate are connected by a ribbon fiber made up of a plurality of optical fibers. 5. Each of the plurality of active terminal devices and one standby terminal device includes a plurality of active terminal devices, and the plurality of active terminal devices are connected between the terminal stations facing each other by the one or more active terminal devices. Performs optical transmission through a plurality of working optical transmission lines connected to each of the terminal station devices, and when a failure occurs in any of the working optical transmission lines, the optical communication is performed via the standby terminal device. In an optical terminal device provided in each terminal of an optical transmission system that performs optical transmission by switching to a standby optical transmission line that connects between the terminal stations, the working optical terminal device inputs a plurality of signals , respectively. Predetermined timing of the working optical terminal equipment
Multiplexed with grayed, and active transmission means for performing active system synchronous optical transmission through the working optical transmission path connected to the current optical terminal station, the preliminary signals after multiplexing in the current optical terminal station Switching means for switching to be connected to the terminal equipment side, wherein the spare terminal equipment is a multiplexed signal from a working optical terminal equipment.
And a plurality of separated signals are input to the standby optical terminal.
And multiplexing at a predetermined timing device, said pre 備光end station
And a backup transmission means for performing a preliminary system synchronizing the optical transmission through the preliminary optical transmission path connected devices, optical terminal apparatus, characterized in that.