JP2002261718A - Method for transmitting/receiving random pattern and optical digital transmitter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem that additional information, such as an alarm transfer or the like due to an input-off of a transmitter side, cannot be detected at a receiver side in such a 0/1 alternating pattern, even by inserting the 0/1 alternating pattern to hole a mark ratio 1/2 of an optical digital transmission line, when the input-off of a low order group signal 101 is detected by an input off detector 2 in the conventional optical digital transmitters. SOLUTION: A method for transmitting/receiving random pattern comprises the steps of installing a PN pattern generator 3 on a receiver side, providing a PN pattern detector 12 at a downstream unit of the receiver side, and changing the 0/1 alternating pattern to be inserted, when the low order group signal 101 is input-off to the PN pattern. Thus, the mark radio 1/2 can be held on the optical digital transmission line, and additional information, such as the alarm transfer or the like due to the input-off can be also detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a random pattern transmission / reception method for preventing signal transmission from being degraded due to a failure in a transmission signal and transmitting the warning for the failure, and an optical digital transmission using the same. Related to the device.

[0002]

2. Description of the Related Art An optical digital transmission apparatus constituting a synchronous network such as SDH or SONET inputs a low-order group signal to a multiplexing circuit, multiplexes additional bits necessary for optical digital transmission, and transmits a plurality of channels 1 to 4. The signal n is further multiplexed into ultra-high-speed data by an ultra-high-speed multiplexing circuit and transmitted to a transmission line. Here, in the conventional optical digital transmission apparatus, when the input disconnection of the signal occurs in the multiplexing circuit of the low-order group, and this is detected by the input disconnection detecting circuit, the mark ratio of the optical digital transmission line is reduced to 1/2. In order to maintain the above, the 0/1 alternation pattern from the 0/1 alternation pattern generation circuit has been inserted into the multiplexing circuit. Additional information such as transfer could not be detected. FIG. 3 shows a transmission side of an optical digital transmission apparatus provided with a conventional 0/1 alternating pattern generation circuit. Channel multiplexing section 100 for channels 1 to n outputs multiplexed data to ultra-high-speed multiplexing circuit 600. The input disconnection detection circuit 200 monitors that the low-order group signal 201 is being input. The 0/1 alternating pattern generation circuit 300
One alternate pattern is generated and output to the selection circuit 400. The selection circuit 400 is controlled by the input disconnection detection circuit 200 so that the low-order group signal 201
When the input is 00, the low-order group signal 201 is selected, and when the input disconnection is detected, the 0/1 alternating pattern from the 0/1 alternating pattern generation circuit 300 is selected. The multiplexing circuit 500 multiplexes an additional bit necessary for optical digital signal transmission with a signal output from the selection circuit 400 and outputs the multiplexed signal to the ultra-high-speed multiplexing circuit 600. The ultra-high-speed multiplex circuit 600
The channel signal from the channel multiplexing unit 1 is further multiplexed with ultra-high-speed data to generate a high-order group signal 202 and output to the E / O converter 700. The E / O converter 7 converts the input high-order group signal 202 from electricity to light, and
Output to 03. In the conventional example, when the input disconnection detecting circuit 2 detects the input disconnection of the low-order group signal 201, the 0/1 alternating pattern generating circuit 3 outputs 0/1 from the 0/1 alternating pattern generating circuit 3 in order to maintain the mark ratio of the optical digital transmission line. Although the alternating pattern has been inserted into the multiplexing circuit 5, in such a 0/1 alternating pattern, 1 and 0 may appear alternately and continuously in the data itself, so that the input on the transmitting side is interrupted on the receiving side. However, there is a problem that transmission of additional information such as receiving an alarm due to the alternation pattern cannot be performed by detecting this alternating pattern.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its objects:
By changing the 0/1 alternating pattern to be inserted when the low-order group signal is cut off to a PN pattern and providing a PN pattern detection circuit on the receiving side, the mark rate on the optical digital transmission line is reduced to 1/2.
An alarm transfer method and optical digital transmission that can ensure clock recovery on the receiving side while retaining additional information, and enable the receiving side to detect additional information such as alarm transfer due to interruption of input of low-order group signals. It is to provide a device.

[0004]

According to a first aspect of the present invention, there is provided a random pattern transmission / reception method for multiplexing additional bits necessary for optical digital transmission on a low-order group signal, and multiplexing the additional bits. In the optical digital transmission device for synchronously multiplexing the signals into a high-order group signal, transmitting the high-order group signal by performing electrical / optical conversion, and separating the low-order group signal from the received high-order group signal, the transmission-side transmission device includes: When a failure is detected in the low-order group signal, a PN pattern is inserted and transmitted instead of the low-order group signal, and the receiving-side transmission device detects the PN pattern, and when a failure occurs in the low-order group signal, Also holds the mark ratio of the optical digital transmission at 1/2,
An alarm transfer of the failure is performed from the transmission side to the reception side. Further, a random pattern transmission / reception method according to a second aspect of the present invention is characterized in that a plurality of the fault targets are detected in the first aspect of the present invention. Also, in the random pattern transmission / reception method according to the invention according to claim 3 of the present invention, the plurality of faults according to the invention according to claim 2 are specified in an input cutoff state of the low-order group signal and the low-order group signal. The low-order group signal includes an AIS state indicating a state where bits of a code are continuous and a REC state indicating a state where the low-order group signal is out of synchronization. An optical digital transmission apparatus according to claim 4 of the present invention multiplexes additional bits necessary for optical digital transmission on a low-order group signal, and synchronously multiplexes a plurality of signals multiplexed with the additional bits. An optical digital transmission device for converting the high-order group signal into an electrical / optical signal, transmitting the high-order group signal, and separating the plurality of low-order group signals from the received high-order group signal. Means for detecting a failure of the group signal; PN pattern generation means; means for selecting the low-order group signal output or the PN pattern output based on the output signal of the failure detection means; Means for multiplexing the additional bits into a signal, wherein the receiving-side transmission device separates the additional bits necessary for the optical digital transmission from a lower-order signal separated from the higher-order group signal; and From said separated signals to said additional bits based on a specific bit of the timing of the bits P
Means for detecting an N pattern and outputting a detection signal, holding the mark ratio of the optical digital transmission at 1/2 even when the low-order group signal fails, and warning the failure from the transmitting side to the receiving side. The transfer is performed. An optical digital transmission apparatus according to a fifth aspect of the present invention multiplexes additional bits necessary for optical digital transmission on a low-order group signal, and synchronously multiplexes a plurality of signals multiplexed with the additional bits. An optical digital transmission device for converting the high-order group signal into a high-order group signal, transmitting the high-order group signal, and separating the plurality of low-order group signals from the received high-order group signal. Means for detecting a plurality of faults of the group signal, a plurality of PN pattern generating means, and one of the low-order group signal output and the plurality of PN pattern outputs based on an output signal of the fault detecting means. Means to choose;
Means for multiplexing the additional bits to the output signal of the selecting means, wherein the receiving-side transmission device separates the additional bits necessary for the optical digital transmission from the lower-order signal separated from the higher-order group signal; Means for identifying and detecting any of the plurality of PN patterns from a signal obtained by separating the additional bit based on the timing of a specific bit of the additional bit, and outputting a detection signal, The mark ratio of the optical digital transmission is maintained at も even when a group signal is faulty, and the fault is forwarded from the transmitting side to the receiving side. Also, in the optical digital transmission device according to the invention according to claim 6 of the present invention, the plurality of faults according to the invention according to claim 5 are such that the input cutoff state of the low-order group signal and the low-order group signal are specified. The low-order group signal includes an AIS state indicating a state where codes are continuous and a REC state indicating an out-of-synchronization state. In the optical digital transmission apparatus according to a seventh aspect of the present invention, the PN pattern generating means according to the fifth aspect is configured by combining a shift register having a plurality of stages and an exclusive OR. , The plurality of PN pattern generating means are different in the number of stages.

[0005]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a first embodiment of an optical digital transmission apparatus according to the present invention. In a transmission side transmission apparatus, a low-order group signal is synchronously multiplexed with a high-order group signal, and an optical fiber transmission line 103 is connected. 1 shows a configuration of a transmission / reception system for transmitting an optical signal via a transmission line and separating the signal into a low-order group signal in a reception-side transmission device. This transmission system is, for example, SDH or SO
Keep in mind that it forms part of a synchronous network such as NET. The transmitting-side transmission device includes a channel multiplexing unit 1
And an ultra-high-speed multiplexing circuit 6 for multiplexing low-order group signals of channels 1 to n output from the channel multiplexing unit 1 into high-order group signals.
And an E / O converter 7 for converting the output of the ultra-high-speed multiplex circuit into an optical transmission signal to an optical fiber. The receiving-side transmission device includes an O / E converter 9 for converting an optical transmission signal from the optical fiber 103 into an electric signal, an ultra-high-speed separation circuit 10 for separating an O / E-converted high-order group signal into a low-order group signal, and , Channels 1 to n, and an ultra-high-speed multiplexing circuit 6 for multiplexing the output of the channel multiplexing unit 1. First, in the transmission-side transmission device, the channel multiplexing unit 1 for each of the channels 1 to n is configured as follows as shown in FIG. The input disconnection detection circuit 2 monitors that the low-order group signal 101 is being input. The PN pattern generation circuit 3 generates a PN pattern which is a random pattern having a mark rate of 、, and outputs the generated PN pattern to the selection circuit 4.
The selection circuit 4 is controlled by the input disconnection detection circuit 2, selects the low-order group signal 101 when the low-order group signal 101 is normally input to the channel multiplexing unit 1, and detects the input disconnection. , The PN pattern from the PN pattern generation circuit 3 is selected. Further, a frame bit inserter 8 is provided.
The multiplexing circuit 5 multiplexes an additional bit necessary for optical digital signal transmission such as overhead, and outputs the multiplexed signal to the ultra-high-speed multiplexing circuit 6, including the output of the frame bit inserter 8 in the signal output from the selection circuit 1. The ultra-high-speed multiplexing circuit 6 further multiplexes the plurality of channel signals from the channel multiplexing unit 1 with ultra-high-speed data to generate a high-order group signal 102 and outputs the high-order group signal 102 to the E / O converter 7. The E / O converter 7 converts the input high-order group signal 102 from electricity to light and outputs it to the optical fiber 103. In the receiving-side transmission device, the optical fiber 103
Is input to the O / E converter 9 to convert a signal from light to electricity. The ultra-high-speed separation circuit 10 separates the high-order group signal 104 from the O / E converter 9 for each channel and outputs it to the separation circuit 11 provided in each channel separation unit 14. Separation circuit 11 separates additional bits from the received signal and outputs low-order group signal 105. The frame bits among the separated additional bits are detected by the frame bit detector 13 and the PN pattern detection timing is output to the PN pattern detection circuit 12. The PN pattern detection circuit 12 monitors whether the low-order group signal 105 is a PN pattern.
An N pattern detection signal 106 is output.

Next, the operation of the optical digital transmission device will be described. The transmitting side device inputs the low-order group signal 101 to the multiplexing circuit 5 of the channel multiplexing unit 1 and
Multiplexes additional bits required for optical digital signal transmission, including frame bits output from the
Output to The ultra-high-speed multiplexing circuit 6 includes a plurality of channels 1 to
The signal n is further multiplexed to the higher-order group signal 102, converted from an electric signal to an optical signal by the E / O converter 7, and transmitted to the transmission line. When the input disconnection detection circuit 2 detects the input disconnection of the low-order group signal 101, the selection circuit replaces the low-order group signal 101 of the corresponding channel by a selection circuit in order to keep the mark ratio of the optical digital transmission line at 1/2. To PN
The PN pattern signal from the pattern generation circuit 3 is selected and inserted into the multiplexing circuit 5. The E / O converter 7 converts the input high-order group signal 102 from electricity to light, and
Output to In the receiving side device, the optical digital signal from the optical fiber 103 is input to the O / E converter 9,
Converts light to electricity. The ultra-high-speed separation circuit 10
The high-order group signal 104 from the / E converter 9 is separated for each channel and output to the separation circuit 11. Separation circuit 11 separates additional bits from the received signal and outputs low-order group signal 105. The frame bit detector 13 outputs a PN pattern detection timing to the PN pattern detection circuit 12. The PN pattern detection circuit 12 monitors whether the low-order group signal 105 is a PN pattern.
An N pattern detection signal 106 is output. Therefore, when the input of the low-order group signal is interrupted, if the PN pattern is inserted on the transmission side and the PN pattern is detected on the reception side, the mark rate on the transmission path can be maintained at 、. The receiving side can determine the input disconnection alarm of the low-order group signal and perform the alarm transfer.

Next, a second embodiment of the present invention shown in FIG. 2 will be described. The optical digital transmission apparatus of FIG. 2 sets the PN pattern generation circuit 3 of FIG. 1 to a different number of PN pattern stages for each alarm on the transmission side, and multiplexes them by a multiplexing circuit 5 and an ultra-high-speed multiplexing circuit 6 and sends them to the transmission line. I do. The receiving side is provided with a detecting circuit having the same number of PN pattern stages as the transmitting side for each channel, so that it is possible to detect additional information such as an alarm transfer on a channel basis. As is well known, the PN pattern generation circuit is configured by combining a plurality of stages of shift registers and an exclusive OR, and the number of stages is different.
The generated pseudo random pattern and the pattern repetition cycle are different. On the transmission side, the PN31 pattern generation circuit 15
Generates a PN31 pattern and outputs it to the selection circuit 4. P
The N20 pattern generation circuit 16 generates a PN20 pattern,
Output to the selection circuit 4. The PN19 pattern generation circuit 17 generates a PN19 pattern and outputs it to the selection circuit 4. The input disconnection detection circuit 2 determines whether or not the low-order group signal 101 is in the input disconnection state, and notifies the selection circuit 4. The REC detection circuit 18 determines whether the low-order group signal 101 is in the REC state (out of frame synchronization) and notifies the selection circuit 4. In the AIS detection circuit 19, the low-order group signal 101 is in the AIS state (abnormal state such as continuous data of "1" and "0").
Is determined, and the selection circuit 4 is notified. The selection circuit 4 selects a PN pattern generation circuit based on information on input disconnection detection, REC detection, and AIS detection, and outputs a signal to the multiplexing circuit 5. On the receiving side, the PN31 pattern detection circuit 20 monitors the low-order group signal 105 and outputs a PN31 pattern detection signal 107 when detecting a PN31 pattern. The PN20 pattern detection circuit 21 outputs the low-order group signal 10
5 is monitored and a PN20 pattern is detected when a PN20 pattern is detected.
It outputs a pattern detection signal 108. The PN19 pattern detection circuit 22 monitors the low-order group signal 105 and outputs a PN19 pattern detection signal 109 when detecting a PN19 pattern. At the transmitting side, the input disconnection of the low-order group signal 101, AIS,
When a REC condition occurs, a different PN
Send a pattern. On the receiving side, the received low-order group signal 10
5 is monitored, and when a corresponding PN pattern is detected, it is possible to determine which of the REC or AIS alarm has occurred on the transmission side of the channel, that is, the input disconnection of the low-order group signal 101 has occurred.

In the above embodiment, the configuration and operation in one optical path have been described. However, the present invention is effective even in a wavelength division multiplexing optical digital transmission system in which a large number of independent optical paths are set. is there.

[0009]

According to the conventional optical digital transmission apparatus, when the input disconnection detection circuit 2 detects the input disconnection of the low-order group signal 101, the mark ratio of the optical digital transmission line is maintained at 1/2 so as to maintain the mark ratio of 1/2. The alternating pattern was inserted into the multiplexing circuit 5. However, with such a 0/1 alternating pattern, it was not possible for the receiving side to detect additional information such as an alarm transfer due to an input cutoff at the transmitting side. As described above, in the optical digital transmission apparatus of the present invention, the PN pattern generation circuit is provided on the reception side, the PN pattern detection circuit is provided on the downstream side on the reception side, and the low-order group signal 10
By changing the 0/1 alternation pattern to be inserted when 1 is cut off to a PN pattern, the mark rate on the optical digital transmission line can be maintained at 、, and at the same time, the addition of alarm transfer due to the cutoff Information can be detected. Further, the PN pattern generation circuit is set to a different number of PN pattern stages for each alarm, and the reception side is provided with a detection circuit of the same number of PN pattern stages as the transmission side for each channel, so that alarm transfer or the like can be performed for each channel. It is possible to detect additional information.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a first embodiment of an optical digital transmission device according to the present invention.

FIG. 2 is a diagram illustrating a configuration of a second embodiment of the optical digital transmission device of the present invention.

FIG. 3 is a diagram illustrating a configuration of a transmission-side device of a conventional optical digital transmission device.

[Explanation of symbols]

 Reference Signs List 1 channel multiplexing unit 2 input disconnection detection circuit 3 PN pattern generation circuit 4 selection circuit 5 multiplexing circuit 6 ultra high speed multiplexing circuit 7 E / O converter 8 frame bit inserter 9 O / E converter 10 ultra high speed separation circuit 11 separation Circuit 12 PN pattern detection circuit 13 Frame bit detector 14 Channel separation unit 15 PN31 pattern generation circuit 16 PN20 pattern generation circuit 17 PN19 pattern generation circuit 18 REC detection circuit 19 AIS detection circuit 20 PN31 pattern detection circuit 21 PN20 pattern detection circuit 22 PN19 Pattern detection circuit 101 Low-order group signal 102 High-order group signal 103 Optical fiber 104 High-order group signal 105 Low-order group signal 106 PN pattern detection signal 107 PN31 pattern detection signal 108 PN20 pattern detection signal 109 PN19 pattern detection signal 100 channel Le multiplexer 200 input break detection circuit 300 0/1 alternating pattern generation circuit 400 selecting circuit 500 multiplexing circuit 600 ultrafast multiplexing circuit 700 E / O converter 201 low-order group signal 202 high-order group signal 203 optical fiber

Claims (7)

[Claims] 1. An additional bit necessary for optical digital transmission is multiplexed on a low-order group signal, and a plurality of signals multiplexed with the additional bit are synchronously multiplexed into a high-order group signal, and the high-order group signal is subjected to electrical / optical conversion. In the optical digital transmission device that separates the low-order group signal from the received high-order group signal, the transmitting-side transmission device, when detecting a failure in the low-order group signal, substitutes for the low-order group signal. The PN pattern is inserted and transmitted, and the receiving-side transmission device detects the PN pattern, holds the mark ratio of the optical digital transmission at 1/2 even when the low-order group signal fails, and A random pattern transmission / reception method, wherein an alarm transfer of the failure is performed to the receiving side. 2. The random pattern transmission / reception method according to claim 1, wherein a plurality of failure targets are detected. 3. An AIS state in which the plurality of faults are in a state where the input of the low-order group signal is cut off and a state in which a bit of a specific code continues to the low-order group signal, and a state in which the low-order group signal is out of synchronization. 3. The random pattern transmission / reception method according to claim 2, further comprising a REC state indicating 4. A low-order group signal is multiplexed with additional bits required for optical digital transmission, and a plurality of signals multiplexed with the additional bits are synchronously multiplexed into a high-order group signal, and the high-order group signal is subjected to electrical / optical conversion. An optical digital transmission apparatus for separating the plurality of low-order group signals from the received high-order group signal, the transmission-side transmission apparatus comprising: means for detecting a failure of the low-order group signal; Means, based on an output signal of the fault detection means, means for selecting the low-order group signal output or the PN pattern output, and means for multiplexing the additional bit to the output signal of the selection means, The receiving-side transmission device is configured to separate an additional bit necessary for the optical digital transmission from a lower-order signal separated from the higher-order group signal, and based on a timing of a specific bit of the additional bit. Means for detecting the PN pattern from the signal from which the additional bits are separated, and outputting a detection signal, wherein the mark ratio of the optical digital transmission is held at 1/2 even when the low-order group signal fails, and An optical digital transmission device for performing alarm transfer of the fault from a receiving side to the receiving side. 5. A low-order group signal is multiplexed with additional bits required for optical digital transmission, and a plurality of signals multiplexed with the additional bits are synchronously multiplexed into a high-order group signal, and the high-order group signal is subjected to electrical / optical conversion. An optical digital transmission device for separating the plurality of low-order group signals from the received high-order group signal, wherein the transmitting-side transmission device includes a plurality of means for detecting a plurality of faults in the low-order group signal; Means for selecting one of the low-order group signal output or the plurality of PN pattern outputs based on an output signal of the fault detecting means, and an output signal of the selecting means, Means for multiplexing additional bits, the receiving-side transmission device comprising: means for separating additional bits required for the optical digital transmission from a lower-order signal separated from the higher-order group signal; Means for identifying and detecting any of the plurality of PN patterns from the signal obtained by separating the additional bit based on the timing of the bits, and outputting a detection signal. An optical digital transmission device, wherein the digital transmission mark rate is maintained at 1/2, and the fault alarm is transferred from the transmission side to the reception side. 6. The plurality of faults indicate an input disconnection state of the low-order group signal, an AIS state in which the low-order group signal indicates a state in which a specific code continues, and a state in which the low-order group signal is out of synchronization. 6. The optical digital transmission device according to claim 5, comprising a REC state. 7. The apparatus according to claim 1, wherein said PN pattern generation means is configured by combining a plurality of stages of shift registers and exclusive OR, and said plurality of PN pattern generation means have different numbers of said stages. Item 6. The optical digital transmission device according to item 5.