JP3199107B2 - Multi-station communication device using ring transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-station communication apparatus using a duplex ring transmission line capable of performing communication without a signal transmission delay when a failure occurs.

[0002]

2. Description of the Related Art Working / spare system (commonly referred to as system 0 / system 1)
In the duplexed transmission path, a number of signal transmission stations are connected in a ring, and a predetermined channel (time slot) is dedicated between the stations for communication.

That is, the format shown in FIG. 6 indicates that communication is performed using channels 1 to n following the synchronization signal F. For example, the channel with the number m is predetermined such as that between the stations A and B shown in FIG. 7 and the channel with the number p is used between the stations C and D as shown in FIG. FIG. 7 schematically shows a duplicated transmission line. In FIG. 7, stations A, B, C, and D do not have an upper and lower hierarchy difference on the transmission path, and are transmitted between an active system (system 0) indicated by a solid line and a standby system (system 1) indicated by a dotted line. Road is connected. Each station is connected to an exclusive input / output device, but is not shown.

[0004] When the above channel is abbreviated as CH, CH1
Is between stations A and C, CH2 is between stations A and C, CH
3 is between stations A and D, CH4 is between stations B and D, C is
H5 is set to be used for communication between the stations C and D. Now, it is assumed that the active system (system 0) is in use and the standby system is on standby, and a failure occurs between the A station and the B station on the active transmission line. When detecting the occurrence of the failure, the station B instructs the standby 1-system transmission line to switch to the working channel. The instruction may be transmitted from the B station to the A station via the 1-system transmission line, and then the A station may transmit the instruction to the next D station. As a result, the transmission path of the first system also becomes ring-shaped.

[0005] However, only the station B detects a fault in the system 0 transmission line, and the transmission means in the station B is not a signal transmitted from the station A on the system 0 transmission line from the station B. Is transmitted. Regardless of the validity of the signal, stations B and subsequent stations are operating the transmission line with a signal present, so each station after station B starts transmitting a valid signal through the system 1 transmission line. I can't know.

Therefore, the operation cannot be switched so as to extract the signal from the system 1 through which the legitimate signal is transmitted. This is because conventional signal transmission stations do not have effective means or pickup means for channel switching.

[0007] Therefore, a folded line FL shown in FIG. 7 is formed in the station B. The return line FL is a connection line that short-circuits the 0-system transmission line and the 1-system transmission line in the B station.
When the return line FL is connected, the signal of the 1-system transmission line becomes
The signal is shunted in the B station and transmitted as a predetermined signal on the 0-system transmission line. Therefore, in the station C, the processing for extracting the signal addressed to the own station from the system 0 transmission line and transmitting the other signals to the station D can be performed irrespective of the presence or absence of the failure in the station B, as before.

[0008]

In the above case, for example, in the station D, signals which are not different from those of the related art by the system 0 transmission line should be transmitted and received through the channels CH3, CH4 and CH5. When examining CH5, it is a signal transmitted in the order of C → B (return line) B → C → D using the system 1 transmission line and B → 0 system transmission line. Therefore, since the signal is transmitted over a long distance compared to the case where the signal is originally transmitted from station C to station D using only the system 0 transmission line, there is no way to cause signal transmission delay. It is.

An object of the present invention is to improve the above-mentioned disadvantages, and each signal transmission station forming a ring-shaped transmission path uses an emergency signal from a signal transmission station which has detected a failure in the transmission path as a trigger, It is an object of the present invention to provide a multi-station communication device capable of obtaining a signal transmission state that hardly changes from a normal state by accessing a transmission line of another system.

[0010]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, reference numeral 10 denotes a signal transmission station, 11 denotes monitoring means for constantly monitoring a channel signal transmitted from another station, 12 denotes a transmission means, 13 denotes a signal transmission line, and 14 denotes a standby channel signal for a local station. Means for taking out from the transmission path, 15 means for notifying the transmission means, 16 means emergency signal transmission means, 21 is the working transmission path, and 22 is the protection transmission path.

According to the first aspect of the present invention, there is provided a monitoring means for constantly monitoring a channel signal transmitted from another station, and including a channel originating from the local station when the local channel signal is received. A signal transmission station 10 having transmission means 12 for transmitting the signal, and the signal transmission station 10 and the signal transmission path 1
3. A multi-station communication apparatus using a ring transmission line which comprises a ring transmission line having the same configuration as the working transmission line and a protection transmission line 22 in the opposite direction to the working transmission line. A means for extracting a channel signal arriving at the local station from the protection system transmission line when detecting a transmission signal interruption or deterioration of transmission line characteristics; and a means for notifying the transmission unit of the transmission signal interruption signal. And the transmitting means 12 has a built-in means 16 for transmitting an emergency signal to all channels other than the local destination channel in accordance with the notified signal.

When a plurality of signal transmission paths 13 and a plurality of signal transmission stations 10 are connected to each other to form a ring transmission path, the monitoring means 11 of the signal transmission station always monitors signals transmitted from other stations. Monitoring. The monitoring means 11 is used for the active transmission line 2
1, when the disconnection of the transmission signal is detected,
2 is started to extract the local destination channel signal from the signal transmitted on the protection transmission line 22. Also, it notifies the transmission means 12 of its own station that the transmission signal has been interrupted.

The transmitting means 12 transmits an emergency signal (a signal indicating occurrence of a fault) as a signal to be transmitted to another station via the active transmission line 21. The signal transmitted from this signal transmission station to another station via the protection transmission line does not include an emergency signal. The invention according to claim 2 describes a limitation condition for a signal transmission station that has received a signal on an active transmission line into which the emergency signal has been inserted. That is, the signal transmission station includes an incoming call switch for switching between the working transmission line and the protection transmission line, and when the monitoring means detects that the channel signal arriving at the local station is an emergency signal, the channel is switched. Only when the access is made to the protection system transmission line 22, the access is changed.

According to a third aspect of the present invention, the signal transmitted through the ring-shaped signal transmission path is a synchronous digital hierarchy (SDH) type signal, and the emergency signal is an alarm transfer function of the same type signal. It is constituted by being transmitted by. According to the present invention, since the emergency signal is transmitted by the alarm transfer function, it is a kind of transmission of the maintenance operation signal,
Processing response can be enabled.

[0015]

FIG. 2 is a block diagram specifically showing FIG. In FIG. 2, reference numerals 21 and 22 indicate the active system (0
1) Transmission line and protection line, 30 is a signal transmission station, 31 is a monitoring means, 32 is a transmission means, and 31 and 32 after the signal transmission station 30 correspond to 10, 11, and 12 in FIG. 1, respectively. I do.

Next, a "REC" 33 is a failure detecting unit, which detects the occurrence of a failure due to loss of frame synchronization due to a signal interruption or the like. Also, the abnormality notification signal detection unit 3
Numeral 4 indicates a portion for detecting the transmitted emergency signal.
Reference numeral 35 denotes a 0/1 system switching unit, which is a switch for switching connection to the other transmission line when an emergency signal is detected on the transmission line.

In the transmission means 32, the abnormality notification signal generator 3
Reference numeral 6 denotes a part for generating an emergency signal. The description of the frame synchronizing unit, the speed converting unit, the multiplexing, and the like in the station will be omitted because they indicate the normal operation locations in the normal signal transmission station.
FIG. 3 is a diagram showing an example of a channel signal format in each state in, for example, the B station in FIG. FIG. 3A shows the state of the REC section signal during use of the working transmission line. It is assumed that a failure has occurred at time T1, and the signal of the REC section has changed from "0" to "1", for example.

FIG. 3B shows a received data format received by the station B. F is a synchronization signal, and 1, 2, 3, to N are channel numbers. FIG. 3C shows an output of the 0/1 system switching unit 35, and shows a signal instructing a standby system switching at time T2.

FIG. 3D shows a transmission signal transmitted from the B station to another station via the working transmission path. After time T2, the hatched portion indicates that an emergency signal is transmitted. R
At the time of EC detection, an emergency signal is inserted for channels other than the channel used by the own station. The fact that the channels 1 and 4 are not hatched indicates that the channel is a channel to be received by the station B. In this way, only the transmission station that has detected an abnormality sends a special signal.

FIG. 4 is a diagram showing a data format in the D station which is ring-connected to the B station shown in FIG. FIG. 4A shows the REC signal during use of the active transmission line, and no abnormality is detected in the D station. FIG. 4B shows received data, in which the signal shown in FIG. 3D arrives at station D via station C via the working transmission line. At this time, with respect to channels 2 and 5, station C on the way is a channel used for another station, in this case, pair A and pair D, so that a normal communication signal is inserted at station C in place of the emergency signal. ing.

In the received data shown in FIG.
Since the signals other than the channel 6 are all emergency signals, the 0/1 changeover switch 4 which detects the emergency signal switches from the 0 system to the 1 system at the position of the channel 3 as shown in FIG. 4C. As described above, according to the first aspect of the present invention, signals transmitted from the previous station are transmitted through the transmission path to the subsequent station on channels other than the channel used in the own station. In FIG. 4, it can be seen from FIG. 4D that the emergency signal is inserted after the channel 6 and before the channel indicated by F.

This emergency signal is obtained by parallel-to-serial conversion for each channel, and it is determined whether or not it matches a predetermined emergency signal. In addition, detection of “the number of protection stages n (where n is an integer of 2 or more)” is a necessary condition for matching determination. FIG. 5 is a diagram schematically showing an SDH ring transmission system. In FIG. 5, an emergency signal for transmitting a transmission line failure detected by the station B to the station C and thereafter is transmitted to the system 0 transmission path from the station B. For example, all “1” signals are used as the AIS signals of the TU2, TU3, and TU4 channels. When this signal is received at stations C and D, the reception transmission line is switched from system 0 to system 1. The transmission of the emergency signal is the same in the case of a device failure other than the transmission line failure. SD
Conventionally, the H transmission system has been put to practical use between opposing stations,
The ring transmission system does not transmit the abnormality detection signal and does not switch the transmission path.

[0023]

According to the first aspect of the present invention, when a failure occurs in a transmission line / device in a ring-shaped working transmission line, each of the stations receiving the notification switches to receiving from the protection transmission line. Execute the process. Therefore, normal communication without signal transmission delay can always be performed.

According to the second aspect of the present invention, the transmission path can be switched using the alarm transfer function in the SDH type transmission path. Therefore, there is no need to transmit the emergency signal using the user bits on the transmission path, and it is not necessary to manage the communication protocol.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a configuration diagram specifically shown in FIG. 1;

FIG. 3 is a diagram showing a channel signal format in station B of FIG. 2;

FIG. 4 is a diagram showing a signal format in a D station in FIG. 2;

FIG. 5 is a diagram schematically showing an SDH ring transmission system.

FIG. 6 is a diagram showing a format of multi-station communication.

FIG. 7 is a diagram showing a duplicated transmission path.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 signal transmission station 11 monitoring means 12 transmission means 13 signal transmission path 14 means for taking out the local destination channel signal from protection transmission path 15 means for notifying transmission means 16 emergency signal transmission means 21 working transmission path 22 protection transmission Road

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-63698 (JP, A) JP-A-6-205028 (JP, A) JP-A-7-183906 (JP, A) JP-A-7-183 264228 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/437

Claims (3)

(57) [Claims] 1. A monitoring means for constantly monitoring a channel signal transmitted from another station, and a transmitting means for transmitting a local station-originated channel signal when receiving a local destination channel signal. A ring transmission line is constituted by the signal transmission station provided, and the signal transmission station and the signal transmission line, and a ring transmission line having a protection transmission line of the same configuration as the working transmission line in the opposite direction is used. In the multi-station communication device, when the transmission signal monitoring means detects a transmission signal disconnection or a deterioration in the characteristics of the transmission path, it extracts the local destination channel signal from the standby transmission path and transmits the transmission signal disconnection to the transmission means. A ring for transmitting an emergency signal to all channels other than the local destination channel in accordance with the notified signal. Transmission line Multi station communication apparatus used. 2. The signal transmission station according to claim 1, further comprising an incoming call switch for switching between an active transmission line and a protection transmission line, and wherein said monitoring means for monitoring a transmission signal in said signal transmission station includes an emergency transmission line. A signal transmission station for use in a multi-station communication device, wherein the signal transmission station transmits a signal for switching the incoming call change-over switch when it detects that a reception signal has been received. 3. A signal transmitted through a ring-shaped signal transmission line is a signal of a synchronous digital hierarchy (SDH) format, and an emergency signal is transmitted by an alarm transfer function of the same format signal. The multi-station communication device according to claim 1.