JP2011228756A - Optical transmission system, optical transmission apparatus and optical transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission system capable of a low-delay transmission and a power saving operation, an optical transmission apparatus and an optical transmission method.SOLUTION: An optical transmission system of the present invention comprises a means in which an optical transmission apparatus (20) disposed between an first optical transmission apparatus (10) and a second optical transmission apparatus (30) acquires frame length information FL1 of a light signal transmitted from the first optical transmission apparatus (10) as well as frame length information FL2 from an optical receiver for receiving a light signal from the second optical transmission apparatus (30), and if a light signal from the optical transmission apparatus (10) is transmitted with low delay based on the two pieces of frame length information FL1 and FL2, or if the optical transmission apparatus (20) is made to operate with power saving as much as possible, instruction information is transmitted for instructing a frame length of the frame length information FL1 to be set as long as possible in a range less than a frame length of the frame length information FL2 to the first optical transmission apparatus (10).

Description

  The present invention relates to an optical transmission device having a function of transmitting an optical signal as it is and a function of converting an optical signal into an electric signal and then converting it again into an optical signal, and in particular, enables low-delay transmission and power-saving operation. The present invention relates to an optical transmission system, an optical transmission device, and an optical transmission method.

  OEO (Optical-Electrical-Optical) conversion for avoiding transmission delays due to electrical processing such as routing, etc. that occurs in relay network transmission devices and reducing the scale of this processing unit as the traffic volume on the Internet increases in recent years Researches on photonic networks that do not perform such are actively conducted (for example, see Non-Patent Document 1). However, in photonic networks such as optical packet switching, it is difficult to realize optical buffers, so in future networks, not all will be replaced with photonic networks, but with existing networks based on electrical processing, It is thought that the network architecture will coexist with these photonic networks.

  Based on the background as described above, a network having both functions of optical processing and electrical processing has been proposed (for example, see Non-Patent Document 2). A system configuration example based on this technology is shown in FIG. The optical transmission system of FIG. 5 includes an optical transmission device 901, an optical transmission device 903, and an optical transmission device 902 connected between the optical transmission devices 901 and 903. The optical transmission device 902 is an optical transmission device from the optical transmission device 901. An optical splitter 9020 that branches the signal, an optical receiver 9021 that receives the branched optical signal, an electrical buffer 9022 that stores electrical signals from the optical receiver 9021, an additional electrical buffer 9023 that is different from the electrical buffer 9022, A determination control circuit 9024 that reads the electrical signal of the buffer 9022 and the electrical signal of the additional electrical buffer 9023, an optical delay line 9025 that transmits the optical signal branched by the optical splitter 9020, and optically amplifies the optical signal from the optical delay line 9025. Optical amplifier 9026 and semiconductor optical amplifier for optically reproducing or saturating the optical signal from optical amplifier 9026 A vessel 9027, and a light modulator 9028 for modulating the electrical signal based on the saturation signal from the semiconductor optical amplifier 9027 electrically buffer 9022 from the additional electrical buffer 9023.

  Here, after receiving the optical signal from the optical transmission device 901, the optical receiver 9021 transmits the header information of the received signal to the determination control circuit 9024. The determination control circuit 9024 uses the received header information based on the received header information. Then, it is determined whether or not the optical signal from the optical transmission device 901 is optically regenerated by the optical amplifier 9026 and the semiconductor optical amplifier 9027. The optical delay line 9025 is an optical delay line corresponding to the time required for signal reception processing by the optical receiver 9021 and signal determination processing in the determination control circuit 9024, and the determination control circuit 9024 receives the optical signal from the optical receiver 9021. And a clock signal generation function, taking into account the time required for the clock signal, the distance of the designed optical delay line 9025, the signal reception processing by the optical receiver 9021, and the signal determination processing in the determination control circuit 9024. The timing at which the optical signal transmitted through the optical delay line 9025 passes through the optical amplifier 9026 and the semiconductor optical amplifier 9027 is matched with the control timing of the optical amplifier 9026 and the semiconductor optical amplifier 9027.

  When the control in Non-Patent Document 2 is performed in the optical transmission apparatus 902, the optical amplifier 9026 and the semiconductor optical amplifier 9027 perform optical regeneration when there is no electrical signal in the additional electrical buffer 9023 for the optical signal from the optical transmission apparatus 901. When the additional electric buffer 9023 has an electric signal, optical saturation is performed by the optical amplifier 9026 and the semiconductor optical amplifier 9027, and then the electric buffer 9022 and the additional electric buffer 9023 are based on the CW light from the semiconductor optical amplifier. The optical signal is modulated by an optical modulator 9028. That is, when the electric signal of the electric buffer 9022 does not collide with the electric signal of the additional electric buffer 9023 in time, it is transmitted through the optical processing route of the optical delay line 9025 → the optical amplifier 9026 → the semiconductor optical amplifier 9027. Transmission is performed by an electrical processing route of the receiver 9021 → the electric buffer 9022 → the optical modulator 9028. This control is a first-in first-out (FIFO) method in which signals are read in the order of arrival (see, for example, Non-Patent Document 3). Here, the data deletion operation by optical saturation in the optical amplifier 9026 and the semiconductor optical amplifier 9027 can be realized by using the characteristics of the semiconductor optical amplifier 9027 (for example, see Non-Patent Document 4).

  With this configuration and control, when there is no electrical signal in the additional electrical buffer 9023, the optical signal from the optical transmission device 901 is not stored in the electrical buffer 9022, but the optical delay line 9025 → the optical amplifier 9026 → semiconductor Since it is transmitted through the optical processing route of the optical amplifier 9027, it is possible to transmit with low delay. Even when there is an electrical signal in the additional electrical buffer 9023, the determination control circuit 9024 preferentially reads the electrical signal in the electrical buffer 9022 over the electrical signal in the additional electrical buffer 9023, thereby staying in the electrical buffer 9022. Since time is reduced, it can be considered that transmission with low delay is possible.

S.J.Ben Yoo, “Optical Packet and Burst Switching Technologies for the Future Photonic Internet,” Journal Lightwave Technology, Vol.24, No.12, pp.4468-4492, December 2006. Shimada Tatsuya et al., “Examination of SOA Multistage Access Network,” Shinso Univ. 2009 B-10-29. Takahashi Takataka, Yamamoto Naoyo, Yoshino Hideaki, Toda Akira, “Intuitive Queuing System”, IEICE, 2003. Satoshi Narikawa, “Gbit-Class Transmission Using SOA Data Rewriter for WDM-PON,” IEICE TRANS COMMUN., Vol.E91-B, No.2, pp.399-408, February 2008.

  However, there are two problems in the configuration and control of Non-Patent Document 2 as described above. One is related to transmission delay. In order to give priority to the transmission delay of the optical signal from the optical transmission device 901, when the optical signal from the optical transmission device 901 is received by the optical receiver 9021, even if there is an electric signal in the additional electric buffer 9023, the electric signal is read out. Is always controlled so that the optical signal from the optical transmission device 901 is transmitted through the optical processing route of the optical delay line 9025 → the optical amplifier 9026 → the semiconductor optical amplifier 9027, the electric signal of the additional electric buffer 9023 is As long as an optical signal is transmitted from the optical transmission device 901, it is necessary to continue waiting in the additional electric buffer 9023, so that the buffer size of the additional electric buffer 9023 needs to be increased. Further, the processing is stopped during reading of the electric signal of the additional electric buffer 9023, and the stop processing is performed so that the optical signal from the optical transmission device 901 passes through the optical amplifier 9026 and the semiconductor optical amplifier 9027. It is necessary to design the optical delay line 9025 longer for the time. As a result, even if transmission is performed through the optical processing route of the optical delay line 9025 → the optical amplifier 9026 → the semiconductor optical amplifier 9027, the delay characteristic is deteriorated.

  Another problem is related to power consumption. FIG. 6 shows an example of the optical input-optical output characteristics of the semiconductor optical amplifier. As shown in FIG. 6, in the optical transmission apparatus 902, it is necessary to control with the optical input A when performing the optical regeneration operation, and to control with the optical input B having the optical saturation characteristic when performing the optical saturation operation. is there. Here, since the optical input B is larger than the optical input A, it is necessary to increase the optical power input to the semiconductor optical amplifier 9027 when performing the optical saturation operation compared to the optical reproduction operation. That is, when performing the optical saturation operation, it is necessary to output a strong optical power from the optical amplifier 9026, so that the power consumption necessary for controlling the optical amplifier 9026 increases.

  The problem here is that the optical transmission system of FIG. 5 does not have a sufficient countermeasure function for the power consumption increase of the optical amplifier 9026 due to the optical saturation operation described above. The optical saturation operation is required when reading the electric signal of the additional electric buffer 9023 and when reading the optical signal of the optical transmission device 901 from the electric buffer 9022. In order to reduce the power consumption of the optical amplifier 9026 in the optical transmission system of FIG. 5, an optical saturation operation is always required when reading the electric signal of the additional electric buffer 9023. This is when the optical signal of the device 901 is read from the electrical buffer 9022.

  As a countermeasure, there is a method of reducing the number of operations that must be performed in a light saturation operation in order to transmit an optical signal from the optical transmission device 901 by the optical transmission device 902. The maximum number of operations is reduced even when there is an electrical signal of the additional electrical buffer 9023 described above, and reading of the signal is stopped, and the optical signal from the optical transmission device 901 is always sent from the optical delay line 9025 to the optical amplifier 9026 to the semiconductor. In this control method, the optical amplifier 9027 is controlled to be transmitted through the optical processing route. However, this control method leads to suppression of power consumption in the optical amplifier, but as described above, there arises a problem that the buffer size of the additional electric buffer 9023 is increased and the optical delay line is extended.

  The present invention has been carried out in the background as described above, and reduces the problems such as the increase in the buffer size of the additional electric buffer 9023 and the extension of the optical delay line 9025 caused by the above-described measures, and the low-delay transmission / power-saving operation. An object of the present invention is to provide an optical transmission system, an optical transmission apparatus, and an optical transmission method that enable the above.

  An aspect of the present invention is to provide the optical transmission apparatus 902 with a function of adjusting the frame length of the optical signal from the optical transmission apparatus 901 in order to achieve the above object.

That is, the optical transmission system of the present invention is an optical transmission system in which three optical transmission devices are connected in a row,
An optical transmission device positioned between the first optical transmission device and the second optical transmission device is
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. And an optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter. In
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and uses the frame length adjuster for the frame length information. Means to send to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. The apparatus further comprises means for transmitting instruction information for increasing the frame length as much as possible to the first optical transmission device via the optical transmitter.

The optical transmission device of the present invention is an optical transmission device positioned between a first optical transmission device and a second optical transmission device in an optical transmission system in which three optical transmission devices are connected in a line. There,
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. And an optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter. In
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and uses the frame length adjuster for the frame length information. Means to send to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. The apparatus further comprises means for transmitting instruction information for increasing the frame length as much as possible to the first optical transmission device via the optical transmitter.

The optical transmission method of the present invention is an optical transmission system in which three optical transmission apparatuses are connected in a line, and is based on the optical transmission apparatus positioned between the first optical transmission apparatus and the second optical transmission apparatus. An optical transmission method,
The optical transmission device is:
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. An optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter,
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The processing procedure of the optical transmission apparatus is as follows:
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and the frame length information is converted into the frame length adjuster. Sending to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, the first length When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. Transmitting instruction information for increasing the frame length as much as possible to the first optical transmission device via the optical transmitter;
It is characterized by including.

  When low delay transmission is desired, as described above, it is necessary to reduce as many times as possible the number of operations that must be performed with optical saturation. According to the optical transmission system of the present invention, by reducing the frame length as much as possible, it is possible to realize a reduction in the number of operations in which the optical saturation operation must be performed. For example, if the transmission band of the optical signal from the first optical transmission device is constant, the number of frames decreases as the frame length of the optical signal increases. Therefore, the smaller the number of frames, the lower the number of operations that must be performed with the light saturation operation. Here, the frame length of the frame length information FL1 is limited to a range that is equal to or smaller than the frame length of the frame length information FL2. If the frame length is longer than the frame length of the frame length information FL2, the second light This is because there is a possibility that the transmission apparatus cannot receive the data. Quantitative consideration of the frame length and the number of operations that the optical saturation operation must be performed will become clear from the description of the embodiments described later.

  In order to save power, not only the number of operations in which the light saturation operation must be performed but also the total time for the light saturation operation is important. The time during which the optical saturation operation is performed in order to transmit the optical signal from the first optical transmission device by the optical transmission device according to the present invention is the number of frames (the number of electrical signals) in which the optical saturation operation must be performed. ) And the time for these frames to be read from the electrical buffer. The time read from the electrical buffer depends on the frame length of the corresponding frame. That is, the longer the frame length, the longer the time for reading from the electrical buffer, and the shorter the frame length, the shorter the time for reading. Therefore, if the frame length is increased, the time required for the optical saturation operation will increase, but if the number of frames required for further optical saturation operation decreases, the total optical saturation operation time can be expected to be reduced. it can. The quantitative consideration of the frame length and the operation time during which the optical saturation operation must be performed will become clear from the description of the embodiments described later.

  According to the present invention, it is possible to provide a low-delay transmission and a power saving function of an optical amplifier in an optical transmission system having both optical processing and electrical processing.

It is a figure which shows the optical transmission system of one Example by this invention. It is a figure which shows the flowchart of the frame length adjustment system in the optical transmission apparatus of the optical transmission system of one Example by this invention. It is a figure which shows the example of a relationship between frame length and the frequency | count of operation | movement which must perform optical saturation operation | movement in the optical transmission system of one Example by this invention. It is a figure which shows the example of relationship between the frame length and the operation time which must perform optical saturation operation | movement in the optical transmission system of one Example by this invention. It is a figure which shows the conventional optical transmission system. It is a figure which shows the example of the optical input-light output characteristic of a semiconductor optical amplifier.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an optical transmission system according to an embodiment of the present invention. FIG. 2 is a diagram showing a flowchart of the frame length adjustment method in the optical transmission apparatus of the optical transmission system according to the embodiment of the present invention. FIG. 3 is a diagram showing an example of the relationship between the frame length and the number of operations that must be performed in the optical saturation operation in the optical transmission system according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an example of the relationship between the frame length and the operation time in which the optical saturation operation is required in the optical transmission system according to an embodiment of the present invention.

  In the optical transmission system according to the embodiment of the present invention, as shown in FIG. 1, three optical transmission devices 10, 20, and 30 are connected in a line, and an arbitrary (for example, existing) first optical transmission device 10 and This is realized by providing the optical transmission device 20 according to the present invention between the second optical transmission devices 30.

  The optical transmission device 20 includes a first wavelength splitter 2001 that demultiplexes the optical signal from the first optical transmission device 10, an optical regenerative modulation unit 210 that transmits the optical signal from the first wavelength splitter 2001, Via a second wavelength splitter 2002 that combines the optical signals from the reproduction modulator 210 and the wavelength splitter 2002 that combines the optical signals from the second optical transmission device 30 and the optical signal from the optical reproduction modulator 210. An optical receiver 201 that receives the signal after the optical receiver 201, an optical transmitter 202 that transmits a signal from the optical receiver 201 to the first optical transmission device 10, and a frame length adjuster that transmits frame length information from the optical transmitter 200.

  The optical regenerative modulation unit 210 splits the optical signal from the first wavelength splitter 2001 that demultiplexes the optical signal from the first optical transmission device 10, and one optical signal from the optical splitter 2100. The optical receiver 2101 for receiving, the electric buffer 2102 for storing the electric signal from the optical receiver 2101, another additional electric buffer 2103 different from the electric buffer 2102, and the header information of the optical signal is read from the optical receiver 2101 And a determination control circuit 2104 having a function of reading an electric signal from the electric buffer and the additional electric buffer, an optical delay line 2105 that transmits the other optical signal among the branched optical signals, and an optical delay line 2105 An optical amplifier 2106 for optically amplifying the optical signal, and a half for optically reproducing or saturating the optical signal from the optical amplifier 2106 It comprises a body optical amplifier 2107, and an optical modulator 2108 which modulates the electrical signals from the electrical buffer 2102 and additional electrical buffer 2103 based on the saturation signal from the semiconductor optical amplifier 2107.

  The determination control circuit 2104 of the optical regenerative modulation unit 210 acquires the frame length information FL1 of the optical signal transmitted from the first optical transmission device 10 based on the header information, and adjusts the frame length information FL1 to the frame length. Means for delivering to the device 200.

  The frame length adjuster 200 acquires the frame length information FL2 from the optical receiver 201 that receives the optical signal from the second optical transmission device 30, and based on the two frame length information FL1 and FL2, When the optical signal from the optical transmission device 10 is transmitted with low delay, or when the optical transmission device 20 according to the present invention is operated with power saving as much as possible, the frame length is within the range of the frame length information FL2 or less. Means for transmitting instruction information for increasing the frame length of the information FL1 to the first optical transmission apparatus 10 via the optical transmitter 202 is provided.

  Here, a feature of the present invention is that a function of adjusting the frame length of the optical signal from the first optical transmission device 10 is provided, thereby providing low delay transmission and a power saving function of the optical amplifier 2106. It is a point to do.

  FIG. 2 shows a flowchart of the frame length adjustment method in the optical transmission apparatus of the present invention. The determination control circuit 2104 of the optical transmission apparatus 20 acquires the frame length FL1 of the transmitted signal based on the optical signal from the first optical transmission apparatus 10 received by the optical receiver 2101, and the frame length adjuster. The information is transmitted to 200 (S101).

  Next, the frame length adjuster 200 acquires the frame length information FL2 from the optical receiver 201 that receives the optical signal from the second optical transmission device 30 (S102).

  Next, the frame length adjuster 200 transmits an optical signal from the first optical transmission device 10 with low delay based on the two pieces of frame length information FL1 and FL2 (in the case of Yes in S103), and further The frame length in the frame length information FL1 is compared with the size of the frame length in the frame length information FL2. If FL1 <FL2 (Yes in S104), the frame length information FL2 is transmitted to the first optical transmission apparatus 10. The instruction information for transmitting the frame length information FL1 as long as possible within a range equal to or less than the frame length is transmitted (S105). If FL1 <FL2 is not satisfied (No in S104), the frame length instruction information is transmitted. No (S106).

  On the other hand, when it is not necessary to transmit the optical signal from the first optical transmission apparatus 10 with low delay (in the case of No in S103), the optical transmission apparatus 20 is operated with power saving (in the case of Yes in S107). Further, the frame length in the frame length information FL1 and the frame length in the frame length information FL2 are compared. If FL1 <FL2 (Yes in S108), the first optical transmission apparatus 10 is compared with the frame length. Instruction information for making the frame length of the frame length information FL1 as long as possible within a range equal to or smaller than the frame length of the information FL2 is transmitted (S109). If FL1 <FL2 is not satisfied (No in S108), the frame length instruction information Is not transmitted (S110). Then, when it is not necessary to operate the optical transmission apparatus 20 with power saving (No in S107), the frame length instruction information is not transmitted from the optical transmission apparatus 20 to the first optical transmission apparatus 10 (S111).

  The acquisition of the frame length information (S101, S102) may be performed in the reverse order or simultaneously, and the determination process (S103, S107) is performed after S107 is performed first and then after determination of No in S107. , S103 may be implemented, and the present invention is not limited to the flow described in FIG.

  As described above, by adjusting the frame length in the optical transmission device 20, low delay transmission and the power saving function of the optical amplifier 2106 can be provided.

  FIG. 3 shows an example of the ratio of the number of operations that the optical saturation operation must be performed when the adjustment method of the frame length adjuster 200 according to the present invention is implemented. The ratio of the optical saturation operation is obtained by dividing the number of frames that must perform the optical saturation operation by the total number of frames transmitted from the first optical transmission device 10. The frame transmitted from the first optical transmission device 10 and the frame transmitted to the additional electrical buffer 2103 are assumed to follow the Poisson process and are read out by the FIFO method. The transmission speed is 1 Gbit / s, the transmission band of the frame transmitted from the first optical transmission apparatus 10 is 512 Mbit / s, and the frame length is calculated as a parameter. One additional electric buffer 2103 has a transmission band of 128 Mbit / s, and the frame length of the frame is variable from 64 to 1518 bytes and is randomly generated. The transmission band described here is a band obtained by combining both the header information and the data information of the frame.

  From FIG. 3, it can be understood that as the frame length is increased, the ratio of the light saturation operation decreases. Therefore, it can be seen that low delay transmission can be realized by adjusting the frame length of the present invention.

  FIG. 4 shows an example of an operation time in which the optical saturation operation must be performed when the adjustment method of the frame length adjuster 200 according to the present invention is implemented. The optical saturation operation time is the total optical saturation operation time when the total number of frames when the frame length of a frame transmitted from the first optical transmission device 10 is 1518 bytes is 1, and as described above, It was determined by multiplying the number of frames (number of electrical signals) that must be operated by the time for which these frames are read from the electrical buffer 2102. The conditions regarding the transmission speed, signal readout method, frame arrival, frame transmission band, and frame length of the frame are the same as in the example shown in FIG.

  From FIG. 4, it can be understood that the light saturation operation time decreases as the frame length increases. Therefore, the power saving function of the optical amplifier can be realized by adjusting the frame length of the present invention.

  In the above-described example, the optical transmission device 20 instructs the first optical transmission device 10 (or the second optical transmission device 30) to change the frame length, so that the first optical transmission device 10 It is assumed that (or the second optical transmission device 30) includes means capable of changing the frame length based on this instruction information.

  The frame length information FL1 is the frame length read from the raw data signal transmitted from the first optical transmission device 10, while the frame length information FL2 is transmitted from the second optical transmission device 30. Note that this is the frame length read from the incoming control signal, not the raw data signal.

  Although the present invention is not limited to Ethernet (registered trademark), for example, in the case of Ethernet, a signal having a certain frame length is transmitted from the first optical transmission device 10 to the second optical transmission device 30. If the second optical transmission device 30 cannot transmit this signal, the frame length information that can be received at the maximum is transmitted from the second optical transmission device 30 to the first optical transmission device 10, and the second optical transmission is performed. The apparatus 30 can be configured to discard the optical signal from the first optical transmission apparatus 10 that could not be normally received. In addition, the first optical transmission device 10 can be configured to perform retransmission to the second optical transmission device 30 again based on the maximum frame length information that can be received. It should be noted that transmission of information (control signal) of the maximum frame length that can be received from the second optical transmission device 30 is not only when the reception is not normally performed as described above, but also periodically (for example, 10 It can be configured to transmit from the second optical transmission device 30 to the first optical transmission device 10 every minute).

  Further, the control signal information from the second optical transmission device 30 is held in the optical transmission device 20 according to the present invention, so that the comparison of the frame length information FL1 and FL2 is realized. FL1 <FL2 In this case, if the frame length of the raw data signal from the second optical transmission device 30 is equal to or smaller than the maximum receivable frame length in the first optical transmission device 10, the first optical transmission device 10 A signal from the second optical transmission device 30 can be received.

  In the above example, the case of the first optical transmission device 10 → the second optical transmission device 30 has been described. However, the transmission of the data signal from the second optical transmission device 30 → the first optical transmission device 10 is explained. It should be noted that the same applies to In this case, the frame length is changed in the same manner as described above within a range satisfying FL1 (maximum receivable frame length of the first optical transmission device 10)> FL2 (frame length from the second optical transmission device 30). Therefore, as an apparatus configuration of the optical transmission apparatus 20 according to the present invention, for example, a frame length adjuster 200, an optical receiver 201, between the first wavelength splitter 2001 and the second wavelength splitter 2002 in FIG. The optical transmitter 202 and the optical regenerative modulation unit 210 may be further provided with configurations in opposite directions. Therefore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  According to the present invention, it is possible to construct an optical transmission system having both optical processing and electrical processing that provides low delay transmission and a power saving function of an optical amplifier, which is useful for any system using an optical transmission device.

10 Optical transmission device (first optical transmission device)
20 Optical transmission device (optical transmission device according to the present invention)
30 Optical transmission device (second optical transmission device)
DESCRIPTION OF SYMBOLS 200 Frame length adjuster 201 Optical receiver 202 Optical transmitter 210 Optical regenerative modulation part 901,902,903 Optical transmission apparatus 2001,2002 Wavelength splitter 2100 Optical splitter 2101 Optical receiver 2102 Electric buffer 2103 Additional electric buffer 2104 Determination control circuit 2105 Optical delay line 2106 Optical amplifier 2107 Semiconductor optical amplifier 2108 Optical modulator 9020 Optical splitter 9021 Optical receiver 9022 Electrical buffer 9023 Additional electrical buffer 9024 Decision control circuit 9025 Optical delay line 9026 Optical amplifier 9027 Semiconductor optical amplifier 9028 Optical modulator

Claims (5)

An optical transmission system in which three optical transmission devices are connected in a row,
An optical transmission device positioned between the first optical transmission device and the second optical transmission device is
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. And an optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter. In
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and uses the frame length adjuster for the frame length information. Means to send to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. An optical transmission system comprising means for transmitting instruction information for increasing the frame length as much as possible to the first optical transmission device via the optical transmitter. The frame length adjuster is
When an optical signal from the first optical transmission device is transmitted with low delay based on the two frame length information FL1 and FL2, the frame length in the frame length information FL1 and the frame length in the frame length information FL2 Only when FL1 <FL2, the frame length of the frame length information FL1 is made as long as possible to the first optical transmission device within a range not exceeding the frame length of the frame length information FL2. 2. The optical transmission system according to claim 1, further comprising means for transmitting instruction information to the first optical transmission apparatus. The frame length adjuster is
Based on the two frame length information FL1 and FL2, when it is not necessary to transmit the optical signal from the first optical transmission device with low delay, when the optical transmission device is operated with power saving, the frame The frame length in the length information FL1 is compared with the frame length in the frame length information FL2, and a range that is less than or equal to the frame length of the frame length information FL2 with respect to the first optical transmission apparatus only when FL1 <FL2. 2. The optical transmission system according to claim 1, further comprising means for transmitting instruction information for increasing the frame length of the frame length information FL <b> 1 as much as possible to the first optical transmission apparatus. In an optical transmission system in which three optical transmission devices are connected in a row, an optical transmission device located between the first optical transmission device and the second optical transmission device,
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. And an optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter. In
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and uses the frame length adjuster for the frame length information. Means to send to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. An optical transmission apparatus comprising: means for transmitting instruction information for increasing the frame length as much as possible to the first optical transmission apparatus via the optical transmitter. In an optical transmission system in which three optical transmission devices are connected in a row, an optical transmission method using an optical transmission device positioned between a first optical transmission device and a second optical transmission device,
The optical transmission device is:
A first wavelength splitter for demultiplexing an optical signal from the first optical transmission device; an optical regenerative modulator for transmitting the optical signal from the first wavelength splitter; and an optical signal from the optical regenerative modulator And a second wavelength splitter that combines the optical signal from the second optical transmission device and the optical signal that is received after passing through the second wavelength splitter that combines the optical signal from the optical reproduction modulator. An optical transmitter for transmitting a signal from the optical receiver to the first optical transmission device, and a frame length adjuster for transmitting frame length information from the optical transmitter,
The optical regenerative modulation unit receives an optical splitter for branching an optical signal from the first wavelength splitter that demultiplexes an optical signal from the first optical transmission device, and one optical signal from the optical splitter. An optical receiver for storing the electrical signal from the optical receiver, another additional electrical buffer different from the electrical buffer, reading header information of the optical signal from the optical receiver, and an electrical buffer And a determination control circuit having a function of reading an electric signal from the additional electric buffer, an optical delay line that transmits the other optical signal among the branched optical signals, and light that optically amplifies the optical signal from the optical delay line An amplifier, a semiconductor optical amplifier that optically regenerates or optically saturates the optical signal from the optical amplifier, and the electrical buffer and the additional electrical buffer based on the saturation signal from the semiconductor optical amplifier. And an optical modulator for modulating electrical signal,
The processing procedure of the optical transmission apparatus is as follows:
The determination control circuit of the optical regenerative modulation unit acquires frame length information FL1 of an optical signal transmitted from the first optical transmission device based on the header information, and the frame length information is converted into the frame length adjuster. Sending to
The frame length adjuster acquires frame length information FL2 from an optical receiver that receives an optical signal from the second optical transmission device, and based on the two frame length information FL1 and FL2, the first length When the optical signal from the optical transmission apparatus is transmitted with low delay, or when the optical transmission apparatus is operated with power saving as much as possible, the frame length information FL1 is within the range of the frame length information FL2 or less. Transmitting instruction information for increasing the frame length as much as possible to the first optical transmission device via the optical transmitter;
An optical transmission method using an optical transmission device.

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