JP3231308B2 - Subscriber line multiplex transmission system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a subscriber line multiplex transmission system in a subscriber multiplex transmission apparatus interposed between an exchange and a subscriber circuit for analog telephones, and in particular, to the subscription thereof. The present invention relates to a subscriber line multiplexing transmission system for preventing each subscriber corresponding circuit in a subscriber circuit from falling into an uncontrollable state due to a transmission error.

[Conventional technology]

Until now, subscription transmission equipment, such as “facility” (No.
7. Vol. 40, 1988, PP30-33), in the optical line multiplexing transmission system, the switching equipment is connected to a subscriber circuit (configured to include a plurality of subscriber corresponding circuits). In addition, in addition to the V signal (voice signal), it is necessary to transmit an S signal (signaling) for controlling a call origination and termination of a subscriber. Until now, when transmitting these S and V signals from the exchange on the office side to the subscriber's circuit, the transmission system is provided with a redundant configuration (consisting of the 0 system and the 1 system).
When a failure occurs in the active system, the system is switched to the standby system to relieve the failure in the transmission system.

[Problems to be solved by the invention]

However, in the related art, the S and V signals themselves are not particularly protected, and may cause a problem in some cases. This is because, when an error occurs in the transmission system, system switching is not performed unless the error reaches a certain level or more.If an error occurs in the S signal from the exchange before performing system switching, There is a risk that the subscriber-corresponding circuit may be stuck (uncontrollable state). If the subscriber-corresponding circuit is stuck, it is no longer possible for the exchange to control the subscriber. is there.

On the other hand, if an error occurs due to a transmission failure in the upstream S signal, the exchange will erroneously recognize the state of the subscriber's telephone, causing a malfunction such as malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a subscriber line multiplexing transmission system in which a subscriber can be controlled from the exchange without the subscriber being stuck even if a failure occurs in the transmission system.

Another object of the present invention is to provide a subscriber line multiplexing transmission system that can easily cope with not only a downlink S signal but also a transmission system failure for an uplink S signal.

[Means for solving the problem]

The above object is achieved by performing data protection on S signals to each of the subscriber corresponding circuits so that an erroneous S signal is not transferred to the corresponding subscriber corresponding circuit. That is, when each of the subscriber corresponding circuits in the analog telephone subscriber circuit is controlled by the multi-frame format signaling (S signal) from the exchange, the subscriber side responds to each of the subscriber corresponding circuits as an S signal. It is determined whether or not the same data has been continuously received N (N: generally an integer of 2 or more) times. If the same data can be received, the S signal is transferred to the corresponding subscriber circuit as a correct signal. While actively controlling, but if you can not receive,
This is achieved by transferring the data of the S signal as all "1" to the corresponding subscriber corresponding circuit and keeping this circuit in the pre-control state until the S signal is continuously received N times.

Another object of the present invention is to monitor the status of an analog subscriber telephone when the same data is continuously transmitted as N signals (N (N)) corresponding to each subscriber telephone on the exchange side of the subscriber multiplex transmission apparatus. : Generally an integer of 2 or more).

[Action]

The S signal from the exchange to the subscriber side constitutes a multiframe for each channel, and its speed is slow in controlling the subscriber side by the exchange. Therefore, the S signal as the same data continuously N times. When the S signal is received, even if the S signal is transferred to the circuit corresponding to the subscriber, no particular problem occurs. When an S signal as the same data is received N times consecutively, the S signal is assumed to be correct and is transferred to the subscriber corresponding circuit, and the subscriber corresponding circuit is actively controlled. is there. On the other hand, if the S signal as the same data is not received continuously N times, the data as the S signal is transferred to the subscriber corresponding circuit as all "1". When the S signal is transferred, the subscriber response circuit is not actively controlled, and maintains the previous control state. Data is all “1”
Instead of transferring the S signal, the same result can be obtained by removing the multi-frame of the S signal and leaving the frame out of frame synchronization.

As described above, when the S signal is protected, it is possible to sufficiently cope with a burst error in the transmission system.

Further, if the same processing is performed for the upstream S signal in addition to the downstream S signal, the exchange can more reliably monitor the state of each of the subscriber telephones, and malfunction in the exchange is prevented. Will be.

〔Example〕

 Hereinafter, the present invention will be described with reference to FIGS.

First, a transmission system according to the present invention will be described. FIG. 2 shows an optical subscriber line multiplex transmission device (CT) as an example of the transmission system.
/ RT). As shown in the figure, an optical line multiplex transmission apparatus is provided with an exchange 1 and a subscriber circuit (multiplexing / demultiplexing function and A / D, D / A switching function, and a plurality of subscriber telephones 1).
S and V signals are bidirectionally transmitted by an optical fiber 12 between the central device CT and the remote device RT.

That is, the S and V signals from the exchange 1 are converted into optical signals by the E / O conversion circuit 4 through the interface circuit 2 in the central unit CT, and are further converted to optical signals in the remote unit RT through the optical fiber 12. After being converted back into an electric signal by the conversion circuit 5, the V signal is directly passed through the interface circuit 9 to the subscriber circuit 10.
The S signal is also transferred to the S signal determination circuit 7, S
The data is transferred to the subscriber circuit 10 via the signal reproducing circuit 8 and the interface circuit 9. The V signal is distributed and D / A-converted to each of the subscriber-corresponding circuits, and is reproduced as voice by the accommodated subscriber telephone set 11. The S-signal controls each of the subscriber-corresponding circuits. It works as much as possible.

On the other hand, various information from the subscriber telephone 11 is stored in the subscriber circuit 10
After being separated and converted into S and V signals by each of the subscriber corresponding circuits, they are multiplexed with those of the other subscriber corresponding circuits, and are then multiplexed with the interface circuit 9 in the remote device RT and the E / O conversion circuit. The optical signal is transmitted on the optical fiber 12 through the optical fiber 6. The S and V signals transmitted through the optical fiber 12 are converted into electric signals by the O / E conversion circuit 3 in the central unit CT and transferred to the exchange 1 through the interface circuit 2.

The essential parts according to the present invention are the S signal determination circuit 7 and the S signal reproduction circuit 8 in the remote device RT. The data protection processing of the S signal is performed by these circuits 7 and 8. Even if any data error occurs in the S signal from the exchange 1 during the transmission, each of the subscriber corresponding circuits in the subscriber circuit 10 is in a stuck state. Is prevented.

FIG. 1 shows a flow of the data protection processing. First, in the S signal determination circuit 7, as shown in the drawing, every time the data of the S signal is captured for each channel, the S signal determination circuit 7 switches between the captured data and the immediately preceding data (data captured in the immediately preceding multiframe). The comparison and collation are performed, and it is determined whether or not the comparison and collation result relating to the match is continuously obtained, for example, three times. When the comparison result concerning the coincidence is obtained three times consecutively, the S signal reproducing circuit 8 transfers the data concerning the coincidence to the subscriber circuit 10 as an S signal, so that each of the subscriber corresponding circuits is controlled. Can be done. On the other hand, if the comparison result relating to the match is not continuously obtained three times, the data of the S signal is all "1" by the S signal reproducing circuit 8, and the multiframe of the S signal is removed. In this state, the data is transferred to the subscriber circuit 10. In the state where the multiframe of the S signal is removed from each of the subscriber corresponding circuits, the previous (controlled) control state is maintained as it is, so that the subscriber corresponding circuit is prevented from being stuck by an erroneous S signal. Can be done.

As described above, the present invention has been described with respect to the downlink S signal.
The processing for such an S signal can be similarly applied to the upstream S signal. For example, a burst error may cause all the subscriber telephone sets to be in an off-hook state, that is, a simultaneous call state, from the point of view of the exchange, but in such a case, the exchange is limited by software processing. In addition, there is a possibility that the exchange may be blocked. If the same processing is performed on the upstream S signal in the central unit of the subscriber multiplex transmission apparatus in order to prevent such a situation, such a situation can be prevented beforehand. It is.

〔The invention's effect〕

As described above, according to the first and second aspects, even if a data error occurs in the S signal from the exchange to the subscriber's circuit, the subscriber's circuit in the subscriber's circuit may fall into a stuck state by mistake. This prevents the unexpected situation that the subscriber circuit is not controlled from the exchange. Further, according to the third aspect, even if a data error occurs in the S signal from the subscriber's circuit to the exchange, the malfunction in the exchange can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a flow of a data protection process for an S signal according to the present invention, and FIG. 2 is a diagram showing an optical line multiplex transmission device (CT / RT) as an example of a transmission system according to the present invention. FIG. 2 is a diagram showing a switching system and a subscriber circuit. 1 ... exchanger, 2,9 ... interface circuit, 3,5 ... O / E conversion circuit, 4,6 ... E / O conversion circuit, 7 ... S signal judgment circuit, 8 ... S signal reproduction circuit , 10 ... subscriber circuit, 11 ... subscriber telephone.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q 1/30-1/50 H04M 3/22-3/36 H04Q 3/42

Claims (3)

(57) [Claims] 1. A subscriber line multiplex transmission system in a subscriber multiplex transmission device interposed between an exchange and an analog telephone subscriber circuit, wherein analog signals are transmitted by a multiframe format signaling (S signal) from the exchange. In controlling each of the subscriber corresponding circuits in the telephone subscriber circuit, the same data as the S signal is continuously N (N: generally 2) corresponding to each of the subscriber corresponding circuits on the subscriber side.
It is determined whether or not the signal can be received (the above integer) times. If the signal can be received, the S signal is transferred to the corresponding subscriber corresponding circuit to control the number of times. Multiplex transmission system in which the data is transferred as "1" to the corresponding circuit corresponding to the subscriber and the circuit is kept in the pre-control state until the S signal is continuously received N times. 2. The subscriber line multiplex transmission system according to claim 1, wherein when the same data cannot be continuously received N times as an S signal on the subscriber side, the multiframe of the S signal is removed. . 3. A subscriber line multiplex transmission system in a subscriber multiplex transmission device interposed between an exchange and an analog telephone subscriber circuit, wherein multi-frame format signaling (S) is sent from the analog telephone subscriber circuit. Signal), the same data is successively transmitted as N signals (N: generally 2) corresponding to each of the subscriber telephones on the exchange side when monitoring the state of each of the analog telephones.
It is determined whether or not the signal can be received (the above integer) times. If the signal can be received, the S signal is transferred to the exchange as a supervisory signal of the subscriber telephone. 3. The system according to claim 1, wherein the data is transferred to the exchange as all "1" s, and the monitoring state of the subscriber telephone is kept in the pre-monitoring state until the S signal is continuously received N times. The subscriber line multiplex transmission system according to any one of the above.