JP2001308814A - Communications equipment for automatic identification of frame configuration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize a fault state and to specify faults place on a transmission line by enabling automatic identification of frame configuration, even in the so-called transparent mode transmission in which a frame is not set in a digital transmission network based on frame synchronization. SOLUTION: The receiving interface part of a slow-speed side receiving transmission line is provided with a frame synchronization detecting part for taking frame synchronization and performing synchronous protection, the frame synchronization detecting part detects a frame synchronous pattern in a received signal, and a multi-frame configuration is accordingly identified even at the transparent mode transmission. Detection and generation of a send alarm is made possible according to the decision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication apparatus for automatically identifying a frame configuration, and identifies a frame configuration even in a transparent mode transmission communication in which a frame configuration is not set, thereby forming a communication network. An alarm can be detected and transmitted in the event of an abnormality. In particular, frame synchronous transmission at a transmission rate of 1.5 Mbit / s, in which communication is performed in a frame configuration of a 12-multiframe configuration or a 24-multiframe configuration. The present invention relates to a frame configuration automatic identification communication device suitable for use in a communication device such as a device.

[0002]

2. Description of the Related Art At present, a frame structure of a frame synchronous transmission having a transmission rate of 1.5 Mbit / s, which is generally used in Japan, has a 12-multiframe structure (hereinafter, referred to as a "multi-frame structure").
There are two types: a "12MF" or a 24 multi-frame configuration (hereinafter referred to as "24MF").

[0003] The signal contains a control signal such as a frame synchronization pattern necessary for establishing communication between opposing devices, in addition to the actual data for communication. By setting the communication device (hereinafter referred to as “non-transparent mode transmission”), communication can be established, a failure state can be recognized, and a failure point on the transmission path can be specified. However, when performing non-transparent mode transmission, the user must know the frame configuration to be used. For this reason, there is a problem that a communication failure occurs due to erroneous recognition of the user or a setting error.

[0004] On the other hand, the frame configuration is not set in each communication device, and the synchronization and operation of the frame are not performed in the communication device as a conventional technology regarding a mode of transmitting through (hereinafter referred to as "transparent mode transmission"). There is a "transparent communication system" in JP-A-6-46100.

[0005] As represented by this prior art, in a transparent mode transmission, a control signal ("control code B" in the specification) such as a frame synchronization pattern necessary for establishing communication is transmitted to a receiving side device. By performing the communication that removes the signal, the user can perform the communication without depending on the frame configuration of the transmitted signal.

[0006]

However, in the conventional transparent mode transmission typified by Japanese Patent Application Laid-Open No. 6-46100, a control signal necessary for establishing communication is removed by a receiving device. There has been a problem that it is difficult to recognize a failure state and to specify a failure location on a transmission line.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to automatically identify a frame configuration even in a transparent mode transmission in a digital transmission network using frame synchronization. Accordingly, an object of the present invention is to provide a frame configuration automatic identification communication device capable of recognizing a failure state and specifying a failure location on a transmission path.

[0008]

In order to achieve the above object, the present invention relates to a frame configuration automatic identification communication apparatus, which comprises a frame used in a digital transmission network in which frame synchronous transmission of a multi-frame configuration is performed. In the automatic identification communication device, the communication device includes a reception interface unit for terminating a reception signal from a low-speed reception transmission line, and a transmission unit for transmitting a transmission signal to a high-speed transmission transmission line. And a frame synchronization detecting section for performing synchronization protection. The frame synchronization detecting section detects a frame synchronization pattern in a received signal to identify a multi-frame configuration.

More specifically, in the above-mentioned automatic identification communication apparatus for frame configuration, the reception interface unit further includes an AIS detection unit for detecting an AIS alarm for notifying that the line is a faulty line, and a bipolar coding rule for a reception signal. A bipolar coding rule violation detecting unit for detecting a violation pulse,
A CRC error detection unit for detecting a CRC operation error of the received signal;
And a SEND detection unit for detecting a SEND alarm for notifying that a transmission abnormality has occurred on the opposite device side when an EC alarm is detected, wherein the CRC error is detected in accordance with the multi-frame configuration determined by the frame synchronization detection unit. The detection unit makes it possible to detect a CRC error.
The detection unit can detect a SEND alarm.

More specifically, in the above-mentioned automatic frame configuration identification communication device, the frame configuration automatic identification communication device further includes a receiving section for terminating a reception signal from the high-speed reception transmission line, and a transmission section for transmitting to the low-speed transmission transmission line. And a transmission interface unit for transmitting a signal, wherein the transmission interface unit has an R signal indicating disconnection of a signal or loss of frame synchronization.
It has a SEND insertion unit that inserts a SEND alarm at a predetermined position in a frame when an EC alarm is detected to notify that there is a transmission error on the opposite device side, and a frame signal processing unit that performs multi-frame signal processing. According to the multi-frame configuration determined by the frame synchronization detection unit, the frame signal processing unit and the SEND insertion unit adapt S to the multi-frame configuration determined by the frame synchronization processing unit.
An END alarm is created.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS. The frame configuration automatic identification communication device of the present invention enables automatic identification of the frame configuration even in a transparent mode transmission state in digital transmission using frame synchronization, thereby enabling predetermined frame errors and the like. The feature is that it is possible to detect the warning of the above.

(I) Outline of Frame Configuration and Principle for Automatically Identifying the Configuration First, the outline of the frame configuration and the principle for automatically identifying the configuration will be described with reference to FIG. Here, in the present embodiment, the communication speed is 1.5 Mbi.
A description will be given by taking 12 MF and 24 MF used in signal transmission of t / s (hereinafter, simply referred to as “1.5 Mbit / s signal”) as an example. FIG. 2 shows 1.5 Mbit
FIG. 3 is a diagram for explaining a frame configuration of a / s signal.

As shown in FIG. 2A, usually,
The frame used in the 1.5 Mbit / s signal is
It is composed of 192 bits (24 time slots × 8 bits) and 1-bit frame (F) bits, for a total of 193 bits. One frame is transmitted every 125 μsec.

The F bit is a bit of a pattern for forming a multi-frame.
The frame is repeated 12 times and makes one cycle. When the frame is 24 MF, the frame is repeated 24 times. This is,
It is a unit called one multi-frame.

[0015] In a method of receiving a frame, F bits are extracted for each frame from the received frame, and recognized as a multi-frame according to a specific frame synchronization detection pattern. That is, a multi-frame is one monitoring section during synchronous communication using frames.

FIG. 2B shows a frame pattern (FP) in the case of 12 MF. The fixed pattern for detecting frame synchronization is (10001101110) as shown in FIG. When such an F-bit frame arrives, the receiving side recognizes that the frame configuration is 12 MF. The twelfth bit is a SEND bit (normal: 0, abnormal: 1), and is a bit indicating an abnormality on the transmitting side of the opposing device. That is, when the F bit of the twelfth frame is 1, it indicates that an abnormality has occurred on the transmitting side of the opposing device. Here, the term “opposite device” means a communication device that is transmitting a signal.

The configuration of the 24 MF shown in FIG. 2C is slightly more complicated than that of the 12 MF, and the configuration as a multi-frame, that is, the meaning of the F bit is FP bit, CRC (Cyclic Redundancy Chec
k) bits and DLK (Data Link) bits. That is, with F bits of 24 multiframes, the fourth, eighth, first,
The 2, 16, 20, 24th frame is a FP bit, the second, 6, 10, 14, 18, and 22nd frame is a CRC bit, and 1, 3, 5, 7, 9, 11, 1
The 3, 15, 17, 19, 21, and 23rd frames are D
Interpreted as LK bits.

As shown in FIG. 2C, the fixed pattern of the 24 MF frame synchronization detection is (00101).
1), and on the receiving side, the fourth, eighth, twelfth, sixteenth, and twentieth
When the F bit of the second frame comes in this pattern, it can be recognized as 24MF.

The CRC bit is a bit for monitoring a code error (CRC operation), and the second, sixth, tenth, fourteenth, eighteenth, and twoteenth bits described as the C bit shown in FIG.
The F bit of the second frame is used for this.

The DLK bit is a bit used for a data link, and is the first, third, fifth, seventh, ninth, and one.
The F bits at the 1, 13, 15, 17, 19, 21, and 23rd frame are used for this purpose. The DLK bit is also used as a SEND bit indicating an abnormality of the opposing device. When an abnormality occurs in the opposing device, all bits are set to “1” or “1111111110000000”.
This is a rule that is sent out as a pattern.

Under such a multi-frame configuration, an important idea of the present invention is to automatically identify the multi-frame configuration using FP bits, which are fixed bits in the multi-frame configuration. That is, 12
The FP bit pattern of the MF is (1000110111
0), and the FP bit pattern of the 24MF is (001).
011), by examining this pattern, it is possible to identify the configuration of a multi-frame even in transparent mode transmission.

(II) Configuration of Communication Device and Method of Communication Now, based on such an idea, a specific configuration of a communication device and a method of communication will be described.

(II-1) Outline of Configuration of Automatically Identifying Frame Configuration Communication Device First, the outline of the configuration of the automatic frame configuration identification communication device according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a frame configuration automatic identification communication device.

In the communication apparatus shown in FIG. 1, when the communication transmission flow enters from the low-speed reception transmission line 2 and exits to the high-speed transmission transmission line 3, the 1.5 Mbit / s reception interface unit 10, When the MUX unit 11 and the transmission unit 12 operate, and conversely, when entering from the high-speed reception transmission line 4 and exiting to the low-speed transmission transmission line 5, the reception unit 15, the DMUX
Unit 14, 1.5 Mbit / s transmission interface unit 13
Will work.

The 1.5 Mbit / s receiving interface unit 10 is a terminal of the network on the low-speed receiving transmission line 2,
The MUX unit 11 has a function of multiplexing the terminated signals, and the transmission unit 12 sends out the multiplexed signal from the MUX unit 11 to the high-speed transmission line 3.

On the other hand, the receiving section 15
And the DMUX unit 14 separates the transmitted multiplexed signal. Then, the 1.5 Mbit / s transmission interface unit 13 transmits those signals to the low-speed transmission transmission line 5.

(II-2) Configuration and Operation of 1.5 Mbit / s Reception Interface Unit 10 Here, 1.5 Mbit / s reception interface unit 10
Let us explain in detail the configuration and operation of this. 1.5M
The bit / s reception interface unit 10 includes an AIS detection unit 10a, a frame synchronization detection unit 10b, a bipolar code error detection unit 10c, a CRC error detection unit 10d, and a SEND detection unit 10e.

The AIS detector 10a is an AIS (Alarm Indication Signal) transmitted from the low-speed side reception transmission line 2.
This is a circuit for detecting an alarm. The AIS alarm is an alarm for notifying an abnormality from a higher-level communication device to a lower-level communication device, when an abnormality is found, assuming that a signal flows as a higher order and a flowing signal as a lower order. It is. Later on how this AIS alert is used,
The case in the prior art and the case in the present invention will be described in detail.

The AIS alarm is sent as continuous "1" data. Therefore, the AIS detection unit 10a counts "0" in the received signal, and determines that an AIS alarm has occurred when the number of "0" included in the received signal for 24 frames is one or less. I will do it. Further, when the number of “0” is two or more, it is canceled.

The next frame synchronization detector 10b detects frame synchronization and determines the configuration of a multi-frame according to the principle described above. The frame synchronization detector 10b is a core component of the present invention, and will be described later in detail with reference to FIG.

Next, the operation of the subsequent circuits will be described. Although the present invention is premised on operating in the transparent mode transmission, the operation of the subsequent circuit described below is the same as the operation in the non-transparent mode transmission. As a result, it is possible to detect a CRC code error and a SEND alarm regardless of the transparent mode transmission.

The operation of the subsequent circuit differs depending on whether the multi-frame configuration is 12 MF or 24 MF.

First, the operation when the configuration of the multi-frame is 12 MF will be described.

The bipolar code error detector 10c detects a violation of the 1.5 Mbit / s received signal in accordance with the bipolar coding rule. As a result, the error rate is 1
When the error rate is equal to or higher than 0 ^-4 , an error rate deterioration alarm is transmitted. When the error rate is equal to or lower than 10 ^-6 , the alarm is canceled.

The next CRC error detection unit 10d is 12MF
Does not work when This is because CRC error detection is not performed in a 12MF multi-frame configuration.

The next SEND detection section 10e is a circuit for detecting a SEND alarm, and receives the SEND bit "1" of the twelfth bit in the multi-frame pattern five times in succession, thereby detecting a transmission error of the opposite apparatus. SE for
When the ND alarm is detected, and when the SEND bit “0” is continuously received three times, it is interpreted that the SEND alarm has been released.

Next, the operation when the multi-frame configuration is 24MF will be described.

When the configuration of the multi-frame is 24MF, no bipolar code detection is performed, and the bipolar code detection unit 10c does not operate.

The next CRC error detector 10d is a circuit for detecting a code error based on a CRC check.
CRC bits in the multi-frame pattern,
The C bit shown in FIG.
When it becomes ^-4 or more, an error rate degradation warning is issued and 10 ^-6
Release the state below.

In the next SEND detector 10e, 12MF
As in the case of the operation at the time of (1), it plays the role of detecting the SEND alarm, but the detection pattern is different. 24
In the case of the MF, the DLK bits in the 24-bit multi-frame pattern, that is, the D bits displayed in FIG. 2C are (11111110000000) patterns, and the pattern is continuously received 16 times. A SEND alarm indicating a transmission abnormality of the other device is detected. On the other hand, it is interpreted that the SEND alarm has been released by receiving the other patterns four times in succession.

Alternatively, if the number of "0" included in the 60 bits of the DLK bit is 1 or less, a SEND alarm is detected, and the number of "0" included in the 60 bits is 4 or more. In this case, it is interpreted that the SEND warning has been released.

(II-3) Configuration and Operation of 1.5 Mbit / s Transmission Interface Unit 13 Next, the configuration and operation of the 1.5 Mbit / s transmission interface unit 13 will be described in detail. 1.
The 5 Mbit / s transmission interface unit 13 includes a CRC insertion unit 13a, a frame signal processing unit 13b, a DLK / SE
It is composed of an ND insertion section 13c.

The communication device according to the present invention is premised on operating in the transparent mode transmission. However, even in the transparent mode transmission, the multi-frame configuration is recognized, the SEND alarm is detected, and
It is characterized by transmitting. In the 1.5 Mbit / s transmission interface unit 13, transmitting a SEND alarm is a feature here. For this reason, under the transparent mode transmission, the 1.5 Mbit / s transmission interface unit 13 only needs to operate at 12 MF based on the multi-frame determination signal generated in the 1.5 Mbit / s reception interface unit 10. Or 24 MF should be operated.

Among the components of the 1.5 Mbit / s transmission interface unit 13, those operating in the transparent mode transmission are the frame signal processing unit 13b and the DL
K / SEND insertion section 13c, and CRC insertion section 13a
Will not work. That is, in the communication device of the present invention, the DLK bit (also used as a SEND alarm) is generated under the transparent mode transmission,
The RC bit is passed through.

As described above, the 1.5 Mbit / s transmission interface unit 13 operates based on the multi-frame determination signal from the 1.5 Mbit / s reception interface unit 10, and operates at 12 MF and at 24 MF. The behavior is different.

First, the operation when the multi-frame configuration is 12 MF will be described.

The DLK / SEND insertion unit 13c is adapted to send a signal to the SEND when a signal input is lost or frame synchronization is lost.
This is a circuit that generates an alarm. In the case of 12MF, specifically, the SEND bit shown in FIG. 2B is inserted to notify the SEND alarm. That is, "1" is inserted into a predetermined SEND bit position of the multiframe to create a SEND alarm. The detection of the loss of frame synchronization is performed by the 1.5 Mbit / s reception interface unit 1.
This is performed by receiving an out-of-synchronization signal transmitted by 0.

The next frame signal processing section 13b is a circuit having a function of monitoring the structure of a frame and inserting necessary F bits. In the case of 12MF operation,
If normal, “100” is set as the FP bit pattern.
When “01101110” generates a SEND alarm, “10001101111” is generated and transmitted to the low-speed transmission line 5 side.

Next, the operation when the multi-frame configuration is 24MF will be described.

The function of the DLK / SEND insertion circuit 13c is to generate a SEND alarm when a signal input is interrupted or frame synchronization is lost, as in the case of the 12MF, but since it is 24MF, the generation pattern is generated. Is different. More specifically, a SEND alarm is generated by inserting a pattern of all bits “1” or “1111111110000000” into the position of the DLK bit shown in FIG. It is sent to the road 5. When out of frame,
Receiving the out-of-sync signal transmitted by the 1.5 Mbit / s reception interface unit 10 is the same as in the case of 12 MF.

The next frame signal processing unit 13b is
In the case of the operation of F, the above-mentioned SEND alarm is put in the position of the DLK bit, the processing as a multi-frame configuration is performed, and the processing is transmitted to the low-speed side transmission transmission line 5.

As described above, the CRC insertion unit 13a does not operate because the communication is performed in the transparent mode transmission.

(III) Configuration and Operation of Frame Synchronization Detector 10b Next, the configuration and operation of the frame synchronization detector 10b will be described in detail with reference to FIG. FIG. 3 is a block diagram illustrating a configuration of the frame synchronization detection unit 10b.

The frame synchronization detecting section 10b is a main technology that forms the core of the present invention, and can identify the configuration of a multi-frame even in transparent mode transmission. As described above, It is possible to detect a SEND alarm or an out-of-synchronization to generate and send a SEND alarm.

In the conventional frame synchronization circuit used for frame-synchronous digital transmission, only one of the circuits synchronized with the multiframe operates during non-transparent mode transmission. In this case, no operation is performed because no frame synchronization is performed. Frame synchronization detector 10b according to the present invention
It should be noted that the feature is that both of the synchronization circuits for identifying the multi-frame are operated to recognize and synchronize the frame pattern of the multi-frame.

When data is sent from the low-speed reception transmission line 2, the 12MF synchronization pattern detection unit 20 extracts data D1 delayed by 193 bits from the reception signal D0 from the transmission line, and further extracts 193 bits from D1. The bit-delayed data D2 is extracted, and the delayed data up to D11 is sequentially extracted.

On the other hand, the 24MF synchronous pattern detecting section 21
Extracts the data D1 delayed by 772 bits from the received signal D0 from the transmission path, extracts the data D2 delayed by 772 bits further from D1, and extracts the delayed data up to D11 in order.

The size of the delay bit of the 12MF synchronization pattern detection unit 20 is 193 bits, and the size of the delay bit of the 24MF synchronization pattern detection unit 21 is 772 bits, that is, 193 × 4. , FP bits in the multi-frame configuration of both.
In the case of 12 MF, as shown in FIG. 2B, F bits are extracted for each frame and FP bits are configured, so that data of 193 bits is examined for synchronization detection. In this case, as shown in FIG. 2 (c), the F bit is extracted every four frames and the FP bit is formed.
× The data of every 4 bits will be examined.

In the next 12MF synchronous pattern matching circuit 22 and 24MF synchronous pattern matching circuit 23, 12MF
The data created by the synchronization pattern detection unit 20 and the 24MF synchronization pattern detection unit 21 are subjected to pattern matching.
As described above, the bit pattern of the FP bit synchronized in 12MF is (1000110111S), and in the case of 24, the bit pattern is different in (001011), and the 12MF and 24MF are erroneously recognized. Never.

12MF synchronous pattern matching circuits 22 and 24
When a pattern matches in any of the MF synchronization pattern matching circuits 23, a pattern matching signal is sent to the rear protection circuit 24. When the number of times reaches the specified number, the rear protection circuit 24 considers that frame synchronization has been established, A synchronization establishment signal reporting that synchronization of either 12MF or 24MF has been established is sent to the next multi-frame determination circuit 2.
5 Here, the backward protection circuit 24 performs the backward protection that is usually performed by the frame synchronization technique, and the backward protection determines that synchronization has been achieved for the first time when the synchronization codes match for a specified number of times. Method. Backward protection is a safety measure to prevent accidentally recognizing that synchronization has been achieved due to an accidental pattern even though the frame has not been synchronized. If four stages of rear protection are used, it is possible to more accurately identify.

The multi-frame determination circuit 25 outputs a multi-frame determination signal 26 and transmits it to each circuit in the communication device. As a result, each circuit can perform an operation conscious of 12 MF and 24 MF even in the transparent transmission mode. To receive the multi-frame determination signal 26, specifically, 1.5 Mbi
Bipolar code detecting section 10c, CRC error detecting section 10 which is a subsequent circuit in t / s receiving interface section 10.
d, SEND detection unit 10e, and 1.5 Mbit / s
The frame signal processing unit 13b and the DLK / SEND insertion unit 13c in the transmission interface unit 13 have been described in (II-2) and (II-3).

Further, the multi-frame determination circuit 25
Upon receiving either the 2MF or 24MF synchronization establishment signal, the synchronization pattern detection unit (20 or 21) on the side where frame synchronization has not been established and the synchronization pattern matching circuit (2).
The detection stop signal 27 for stopping the operation of 2 or 23) is output. This is because the circuit that is not in frame synchronization is unnecessary.

The above is the operation up to frame synchronization. Next, the operation when frame synchronization is lost will be described below.

When frame synchronization is established and the operation of the synchronizing pattern matching circuit (22 or 23) on the operating side detects a mismatch of the synchronizing pattern, the mismatch of the pattern is sent to the forward protection circuit 28. Has reached the prescribed number of times, it is determined that the frame is out of synchronization, and the
To the multi-frame determination circuit 25. Here, the forward protection circuit 28 performs forward protection that is usually performed by the frame synchronization technique. The forward protection means that the synchronization is lost for the first time when the synchronization codes do not match for a specified number of times. It is a technique to judge.

The multi-frame judging circuit 25 releases the detection stop signal 27 by this, and operates both the synchronous pattern detecting sections (20 or 21) and the synchronous pattern matching circuit (22 or 23). The operation for establishing frame synchronization is started.

When controlled by the multi-frame control signal 30 from an external control device or the like, the multi-frame determination circuit 25 gives priority to the control content of the multi-frame control signal 30 over the result of its own determination, and This is reflected on the frame determination signal 26 and the detection stop signal 27.
Such a multi-frame control signal 30 may be sent when the communication mode is set to the non-transparent mode transmission.

(IV) Maintenance work in a communication network using a conventional communication network and a frame configuration automatic identification communication device according to the present invention. Next, in order to show the advantages of the present invention, FIGS. A description will be given of a comparison of maintenance work between a communication network of the related art and a communication network using the frame configuration automatic identification communication device according to the present invention. FIG. 4 is a schematic diagram for explaining fault evaluation in three types of patterns in a conventional communication network in transparent mode transmission. FIG. 5 is a schematic diagram for explaining fault evaluation in three types of patterns in a communication network using the frame configuration automatic identification communication device according to the present invention in transparent mode transmission.

The transmission speed of the communication network is 1.5 Mbit / s as described in the above examples, and it is assumed that communication is performed by transparent mode transmission.

The model is simplified, as shown in FIG. 4, as shown in FIG.
The station subscriber transmission device 43 and the relay transmission device 42 are arranged, and when the device detects an alarm indicating a failure, it is considered how to evaluate in which section the failure has occurred. Note that a low-speed transmission path is provided between the subscriber transmission device 40 and the relay transmission device 41 at the station A, and the transmission is multiplexed by the relay transmission device 41 so that the relay transmission device 41 and the relay transmission device 42 Be careful to hit the road.

First, a case where transparent mode transmission is performed in a conventional communication network will be described with reference to FIG.

(Pattern 1) Subscriber transmission device 40 of station A
When REC Alarm is Detected in REC alarm is an alarm that is issued when signal input is lost or frame synchronization is lost. When the REC alarm is detected by the subscriber transmission device 40 of the A station, the subscriber transmission device 40 notifies the transmission side abnormality of the opposite device of SEND.
Generate and send alerts.

Since the relay transmission device 41 is in the transparent mode transmission, the SEN from the subscriber transmission device 40
The multiplexed high-speed signal is transmitted without recognizing the D alarm. This is because the transparent mode transmission is a transmission mode that does not recognize the frame configuration, and thus does not recognize the contents of such an alarm.

The relay transmission device 42 separates the high-speed signal from the relay transmission device 41, and transmits a 1.5 Mbit / s signal including the SEND alarm transmitted from the subscriber transmission device 40. The subscriber transmission device 43 receives the 1.5 Mbit / s signal including the SEND alarm, and detects the SEND alarm.

Therefore, in this case, the subscriber transmission device 40 of the station A only receives the REC alarm and the subscriber transmission device 43 of the station B only receives the SEND alarm, and a failure occurs between the two devices. I just know that it has happened. This faces a very difficult maintenance problem.

(Pattern 2) When REC alarm due to signal input disconnection is detected in relay transmission device 41 In a conventional communication network, in a transparent mode transmission, the relay transmission device does not detect out-of-frame synchronization, but does not detect a signal loss. It is possible to recognize the REC alarm of the input interruption. In such a case, the relay transmission device 41 generates and sends an AIS alarm. The AIS alarm is a signal issued from a higher-level communication device to a lower-level communication device in the signal flow, and the relay transmission device 41 of the A station issues an AIS alarm toward the B station. This AIS alarm is received by the subscriber transmission device 43. In this case,
The relay transmission device 41 receives the REC alarm, and the subscriber transmission device 43 detects the AIS alarm.
It can be estimated that the section including 1 is a failure section, and the failure section is also between the subscriber transmission device 40 and the subscriber transmission device 43.

(Pattern 3) When the Signal Received by the Relay Transmission Device 41 is Out of Frame Synchronization Next, it is assumed that the signal received by the relay transmission device 41 is degraded until it reaches the out of frame state.

The relay transmission device 41 cannot detect a REC alarm due to loss of frame synchronization because of the transparent mode transmission.

Therefore, a high-speed signal obtained by multiplexing the signal received from the subscriber transmission device is simply transmitted to the high-speed network. The relay transmission device 42 separates the high-speed signal from the relay transmission device 41, and sends out the deteriorated 1.5 Mbit / s signal to the subscriber transmission device 43 until the frame synchronization is lost.

The subscriber transmission device 43 includes a relay transmission device 42
The REC alarm is detected by receiving the signal from.

In this case, the subscriber transmission device 43
Since only the C alarm is received, it cannot be specified at which point the failure has occurred. In this case, too, a problem that is difficult to maintain arises in Pattern 1,
This is the same as pattern 2.

Next, a case in which a transparent mode transmission is performed in a communication network using the frame configuration automatic identification communication device according to the present invention will be described with reference to FIG.

The frame configuration automatic identification communication device described so far includes the relay transmission device 41 and the relay transmission device 42.
Note that it will be installed inside.

(Pattern 1) Subscriber transmission device 40 of station A
In the case where the REC alarm is detected in, when the REC alarm is detected in the subscriber transmission device 40 of the station A, the subscriber transmission device 40 generates and sends a SEND alarm for notifying the transmission side abnormality of the opposite device.

The relay transmission device 41 provided with the automatic identification and communication device for frame configuration of the present invention can detect the SEND alarm despite the transmission in the transparent mode. This is a point different from the conventional relay transmission device.

As described above, the SEND alarm is an alarm indicating an abnormality from the opposing device through which a signal flows, and therefore, the failure section includes the device that has detected the REC alarm,
This can be specified between the devices that have detected the SEND alarm, that is, between the subscriber transmission device 40 and the relay transmission device 41, which is extremely advantageous for maintenance.

(Pattern 2) In the case where the relay transmission device 41 detects the REC alarm due to the interruption of the signal input.
The detection of the alarm is the same as that of the prior art, but the relay transmission device provided with the frame configuration automatic identification communication device according to the present invention generates SEND and sends it to the subscriber transmission device 40. That is different. It is the same as in the prior art that an AIS alarm is issued in the direction of the station B and the subscriber transmission device 43 receives the AIS alarm.

In order to detect the SEND alarm, the subscriber transmission device 40 has a failure section between the device that has detected the REC alarm and the device that has detected the SEND alarm, the relay transmission device 41 and the subscriber transmission device. It can be specified that it is between 40 and 40.

In the prior art, a faulty section could be specified only in a section including the relay transmission apparatus 41. In the present invention, however, it is specified that the faulty section is between the subscriber transmission apparatus 40 and the relay transmission apparatus 41. become.

(Pattern 3) When Signal Received by Relay Transmission Apparatus 41 is Out of Frame Synchronization In this case, according to the prior art, during transmission in the transparent mode, the relay transmission apparatus 41 detects out of frame synchronization. Although it was not possible, in the relay transmission device 41 in which the frame configuration automatic identification communication device according to the present invention is installed,
An REC alarm due to loss of frame synchronization can be detected. Then, a SEND alarm is sent to the subscriber transmission device 40. As a result, a failure section can be identified as a failure section between the device that has detected the REC alarm and the device that has detected the SEND alarm, that is, between the relay transmission device 41 and the subscriber transmission device 40.

In the case of pattern 2, REC when signal input is interrupted
It is an alarm, and even in transparent mode transmission, AI
An S alarm is generated. In comparison with the S alarm, a REC alarm due to loss of frame synchronization is obtained in the case of pattern 3,
In this case, under transparent mode transmission,
No AIS alarm is generated.

Therefore, the subscriber transmission device 43 only detects the REC alarm, but the subscriber transmission device 40 detects the SEND alarm as described above, so that it is possible to specify the failure section. Here is pattern 2
However, since it is the same that the failure transmission section can be specified between the relay transmission device 41 and the subscriber transmission device 40, the advantage in maintenance can be similarly evaluated.

[0092]

According to the present invention, in a digital transmission network using frame synchronization, the frame configuration can be automatically identified even in transparent mode transmission,
Thus, it is possible to provide a frame configuration automatic identification communication device capable of recognizing a failure state and specifying a failure location on a transmission line.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a frame configuration automatic identification communication device.

FIG. 2 is a diagram for explaining a frame configuration of a 1.5 Mbit / s signal.

FIG. 3 is a block diagram illustrating a configuration of a frame synchronization detection unit 10b.

FIG. 4 is a schematic diagram for explaining fault evaluation in three types of patterns in a conventional communication network in transparent mode transmission.

FIG. 5 is a schematic diagram for explaining fault evaluation in three types of patterns in a communication network using the frame configuration automatic identification communication device according to the present invention in transparent mode transmission.

[Explanation of Codes] 1 ... Automatic identification communication device for frame configuration 2 ... Low-speed reception transmission line 3 ... High-speed transmission transmission line 4 ... High-speed reception transmission line 5 ... Low-speed transmission transmission line 10 ... 1.5Mbit / s reception interface Unit 10a AIS detection unit 10b Frame synchronization detection unit 10c Bipolar code error detection unit 10d CRC error detection unit 10e SEND detection unit 11 MUX unit 12 Transmission unit 13 1.5 Mbit / s transmission interface unit 13a CRC insertion unit 13b ... Frame signal processing unit 13c ... DLK / SEND insertion unit 14 ... DMUX unit 15 ... Reception unit 20 ... 12MF synchronization pattern detection unit 21 ... 24MF synchronization pattern detection unit 22 ... 12MF synchronization pattern matching circuit 23 ... 24MF synchronization pattern Verification circuit 24 Backward protection circuit 25 Multiframe determination circuit 2 ... multi-frame determination signal 27 ... detection stop signal 28 ... forward protection circuit 29 ... out-of-sync signal 30 ... multi-frame control signal 40 ... subscriber transmission device 1 41 ... relay transmission device 1 42 ... relay transmission device 2 43 ... subscriber transmission Device 2

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 29/14 H04L 13/00 313 (72) Inventor Keiichi Otani 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Hidemasa Narita 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5K014 AA01 BA01 FA09 5K028 AA14 KK01 KK03 KK12 MM09 MM17 NN02 NN12 PP05 PP12 QQ02 5K034 AA06 HH02 HH05 HH09 HH12 HH63 JJ24 PP05 TT01 TT02 5K035 CC03 EE02 EE10 FF02 5K047 AA12 CC01 HH02 HH11 HH21 HH57 KK04 KK13 KK17

Claims (3)

[Claims] 1. A receiving interface unit for terminating a signal received from a low-speed receiving transmission line, comprising: a receiving interface unit for terminating a signal received from a low-speed receiving transmission line; A transmission section for transmitting a transmission signal to a channel, the reception interface section including a frame synchronization detection section for performing frame synchronization and performing synchronization protection, and the frame synchronization detection section includes a frame synchronization pattern in the reception signal. A frame configuration automatic identification communication device characterized in that a multi-frame configuration is identified by detecting a frame configuration. 2. An AIS detecting section for detecting an AIS alarm for notifying that a line is faulty, and a bipolar coding rule violation detecting section for detecting a bipolar coding rule violation pulse of a received signal. A CRC error detection unit for detecting a CRC calculation error of a received signal; and a SEND alarm for notifying that a transmission error has occurred on the opposite device side when detecting a REC alarm indicating signal input disconnection or loss of frame synchronization. A SEND detection unit for detecting, according to the multi-frame configuration determined by the frame synchronization detection unit, the CRC error detection unit enables detection of a CRC error, and the SEND detection unit detects a SEND alarm. 2. The automatic frame configuration identification communication device according to claim 1, wherein the communication device is capable of performing automatic identification. Further, the frame configuration automatic identification communication device has a receiving section for terminating a received signal from a high-speed receiving transmission path, and a transmission interface section for transmitting a transmission signal to a low-speed transmitting transmission path. The transmission interface unit inserts a SEND alarm at a predetermined position in a frame when a REC alarm indicating a loss of signal input or loss of frame synchronization is detected at a predetermined position in the frame. And a frame signal processing unit that performs multi-frame signal processing. According to the multi-frame configuration determined by the frame synchronization detection unit, the frame signal processing unit and the SEND insertion unit
3. The communication apparatus according to claim 1, wherein a SEND alarm adapted to the determined multi-frame configuration is created.