JPH01154643A - Transmission control system - Google Patents

Abstract

PURPOSE:To correct the error even for a burst error of control information by providing an error correction code generating section and an error correction processing section respectively to an intra-station terminator and a remote terminator. CONSTITUTION:A digital exchange 1 and a subscriber terminator 2 are connected by a multiplex transmission line 5 via the intra-station terminator 3 and the remote terminator 4 to send the information between subscribers and the control information with multiplex. In this case, an error correction code generation section 6 and an error correction processing section 7 are provided respectively to the intra-station terminator 3 and the remote terminator 4. Since an error correction code to correct 1-bit error generated by the generation section 6 is added to the circuit information between the exchange 1 and the terminator 2 and the result is sent, error correction is applied by the error correction processing section 7 at the receiver side in the presence of 1-bit error.

Description

[Detailed Description of the Invention] [Summary] In a system in which a digital exchange and a subscriber terminal are connected via an in-office terminal and a remote terminal, transmission errors in control information can be corrected. With regard to the transmission control system that has been developed, the aim is to be able to correct burst errors in control information. In a transmission control method in which information and control information between subscribers is multiplexed and transmitted through a multiplexed transmission path, the in-office terminal device and the remote terminal device have an error correction code generation unit and an error correction code generator. a correction processing unit is provided, and the error correction code generated by the error correction code generation unit is added to the control information between the digital exchange and the subscriber terminal equipment, and sent in a multiframe format, and the error correction The error correction processing section is configured to receive control information to which a correction code is added and perform error correction in the error correction processing section.

[Industrial application field]

The present invention relates to a transmission control method that is capable of correcting transmission errors in control information in a system in which a digital exchange and a subscriber termination device are connected via an in-office termination device and a remote termination device. It is.

The l5DN (integrated service digital network) consists of a residential line termination unit (DSU) that accommodates subscriber terminal equipment, and
In-office subscriber terminal equipment (SLT) that constitutes the interface
A system connected to a digital exchange via E) is common. In addition, if the subscriber is in a remote location from the digital switch, a subscriber terminal equipment (SLTE) is installed on the subscriber side, and a subscriber terminal is installed between the subscriber terminal equipment (SLTE) and the digital switch. Systems are also known that are connected via a remote termination (RT) and a local termination (CT) on the central office side.

In such systems where subscribers are located in remote locations, control information between the digital exchange and the subscriber terminal equipment (SLTE) is transmitted between the local terminal equipment (CT) and the remote terminal equipment (RT). It is multiplexed between the two and transmitted, and it is desired that there be no transmission errors.

[Conventional technology]

As mentioned above, when the subscriber is located relatively close to the digital exchange, as shown in FIG. 71 composition has been adopted. That is, a plurality of main line termination units (DSU) 33 are connected to the digital switch 31 via a local subscriber termination unit (SLTE) 32, and
An arbitrary number of data terminal devices 34 and telephone terminal devices 35 are connected to the terminal 3. The in-office subscriber terminal 32 has multiplexing and demultiplexing functions, and is connected to the digital exchange 31 via, for example, a 4 Mb/S highway.

If the subscriber is located far away from the digital exchange, the configuration shown in FIG. 6 is adopted. That is, a subscriber terminal equipment (SLTE) 42 is installed on the subscriber side, and this subscriber terminal equipment 42 is connected to a plurality of home line terminal equipment (DS
U) 43 and between it and the digital exchange 41,
An in-office termination device (CT) 44 is provided, a remote termination device (RT) 45 is provided on the subscriber side, and a transmission path 46 connects the in-office termination device 44 and the remote termination device 45.
The various information multiplexed into 6.6 Mb/S is transmitted at, for example, 6.3 Mb/S.

In the configuration shown in FIG. 6, a subscriber termination device 42 is installed on the subscriber side, and an in-office termination device 44, a transfer path 46, and a remote termination device 45 are interposed between the subscriber termination device 42 and the digital exchange 41. Therefore, it is necessary to configure the subscriber terminal device 42 so that it can transmit control information and the like in a nearly error-free state similar to when it is installed in a station as shown in FIG.

For this purpose, a parity focus is added to the control information and sent, and if a parity error is detected, the previous information in which no parity error occurred is retained, and it is retained until the error disappears. A freezing method is used to output the information that has been stored.

[Problem that the invention seeks to solve]

In the case of control information transmitted between the digital exchange 41 and the subscriber terminal device 42, for example, status information transmitted at a predetermined cycle in call connection control, the parity bit is added and transmitted as described above. If a transmission error occurs due to noise in the transmission path 46, etc., a parity error will occur, and when a parity error is detected, the previous status information where there was no parity error is output. . Therefore, if the state information is information for sequential state transitions such as A-B-0-D-E, the state may be skipped.

For example, when transitioning from state B to state C, if a parity error is detected in the state information of state C, the previous state
Status information indicating status B will be output. When a parity error is detected after 4t[, status information indicating status B will be output each time. Then, if no parity error is detected in the state information to be transitioned to the next state, the state is transitioned from state LQB to state GC, skipping state LQB. In other words, the state transition pattern is no longer normal, resulting in malfunction.

Furthermore, when a burst error occurs, if it is an even-numbered bit error, it cannot be detected as a parity error, and there is a drawback that control is performed according to control information containing the error.

An object of the present invention is to enable correction of burst errors in control information.

[Means for solving problems]

The transmission control method of the present invention distributes control information in a multi-frame format and transmits it with an error correction code added thereto, and will be explained with reference to FIG.

A multiplex transmission line 5 is connected between the digital exchange 1 and the subscriber terminal 2 via the local terminal 3 and the remote terminal 4.
In a transmission control method in which information and control information between subscribers is multiplexed and transmitted, the in-office terminal device 3 and the remote terminal device 4 have an error correction code generation section 6 and an error correction processing section 7. are provided, respectively, and an error correction code capable of correcting a 1-bit error, such as a Hamming code generated by the error correction code generation unit 6, is added to the control information between the digital exchange 1 and the subscriber terminal equipment 2 to generate a multiframe. format, and receive control information with an error correction code added,
The error correction processing unit 7 performs error correction when there is a 1-bit error.

[Effect]

Since an error correction code is added to the control information and transmitted in a multi-frame format, the control information and error correction code are distributed over multiple frames and transmitted, so even if a burst error occurs, the control information In most cases, this will be a 1-bit error, and since the 1-bit error can be corrected using an error correction code, correct control information can be transmitted.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, and 11 is a block diagram of an embodiment of the present invention.
70 type digital exchange, 12 is a subscriber terminal equipment,
13 is an in-office termination device, 14 is a remote termination device, 5 is a transmission line, 16 is a home line termination device, 17 is a data terminal device,
18 is a telephone terminal device, 21.23 is a transmitter having a function of transmitting control information in a multi-frame format, 22.24
25.27 is an error correction code generation unit, and 26.28 is an error correction unit. This is the processing section.

As the error correction code, for example, a Hamming code capable of correcting a 1-bit error can be used.

In that case, if the control information is made up of 8 bits, for example, 4
All that is required is to add a bit-structured error correction code. In order to generate such an error correction code and add it to the control information, a 4-bit error correction code is added to the control information using a read-only memory (ROM) that is accessed using 8-bit control information as an address. It is possible to adopt a configuration in which a total of 12 bits of transmitted information are read out.

That is, the error correction code generation sections 25 and 27 can be constructed from read-only memories (ROMs) as described above.

The control information to which this error correction code has been added is sent from the transmitter 21.23 to the transmission line 15 in a multiframe format.

In addition, the receiving units 22 and 24 receive transmission information in a multi-frame format, and each frame consists of an error correction code and control information.
Since 1-bit error correction is performed using 2-bit transmission information, one
A configuration may be adopted in which control information having an 8-bit configuration in which bit errors have been corrected is read out. That is, the error correction processing sections 26 and 28 can be constructed from a read-only memory (ROM) as described above. If there is a 2-bit error,
The error detection signal can be configured to be read out,
A freezing method can be used in which the previous control information is output when the error detection signal is read.

FIG. 3 is an explanatory diagram of a frame configuration of an embodiment of the present invention,
(a) is a B channel, and tb) is a D channel at 128 timesloft on a 4 Mb/S highway between the digital exchange 11 and the local terminal equipment 13, respectively.
Indicates the frame format that constitutes the frame, fa
), IB, 2B,
As shown in ..., 30 subscribers' B channels are allocated, and 30 subscribers' B channels are allocated by 60 time slots from the 69th time slot to the 128th time slot after 4 time slots. There is.

Also in (bl), similarly to (al), 60 time slots from the 5th time slot to the 64th time slot allow 3 times as shown by ID, IC, 2D, 2C, etc.
0 subscriber's various data and control signals are transmitted from the 69th time slot to the 12th time slot after 4 time slots.
30 by 60 time slots up to 8 time slots
Various subscriber data and control signals are transmitted. (C1 is an enlarged view of the fifth to eighth time slots described above, ID and 2D are time slots for various data with an 8-bit configuration, and Ic and 2C are control signals CI I to CIa+ with an 8-bit configuration. CZI~C2
This is time slot B.

Further, (d) shows information of, for example, 6.3 Mb/S on the transmission line 15 between the local terminal device 13 and the remote terminal device 14,
Information for two subscribers is transmitted in five time slots. That is, frame BF18 of 5 time slots from the 89th time slot to the 93rd time slot is (el
The 89th time slot and the 90th time slot are shown enlarged in
IBl, I of the subscriber's B channel consisting of time slots
B2 time slot, 2B, 2B of other subscribers' B channels in the 91st and 92nd time slots
Various data D j + + control signals C, , C, , various data D j 2 + control signals C3J, and multi-frame signal MF are transmitted at the 2nd time loft and the 93rd time loft.

FIG. 4 is an explanatory diagram of control signals and error correction bits according to an embodiment of the present invention. One multiframe is composed of 24 frames, and 4-bit error correction bits are added to an 8-bit control signal. Shown on the left. CI on the left side of this
, C2, C3 column CIl~clal Cz+”Cza
+ Cz+ to C3g are 8-bit configuration control signals, and t
If"' L 14* t21~j t4r j
! 1 to t34 indicate error correction bits EC having a 4-bit configuration, and column C4 indicates multiframe bits. Also, in order to transmit a total of 12-bit signals consisting of an 8-bit control signal and 4-bit error correction bits in 24 frames, the signals are arranged vertically in 24 bits as shown.

Then, as shown on the right side, data bit DJl and control signal CIl+
CZI and Databit Dj! , control signal C31, and multi-frame bit MF O are inserted and transmitted. Similarly, control signals and error correction bits are distributed and transmitted in each frame F2 to F24.

For example, regarding the control signal from the digital exchange 11, the transmitting unit 21 of the local terminal device 13 accesses the error correction code generating unit 25 using the 8-bit control signal as an address, and generates a 12-bit error correction code with a 4-bit error correction code added. A control signal with a bit configuration is read out, and as shown on the left side of FIG. 4, 24 bits are arranged vertically, and this is converted vertically and horizontally, so that each bit is arranged vertically as shown on the right side of FIG. The frame is sent from the transmitter 21 to the transmission path 15.

The receiving section 22 of the remote terminal device 14 accumulates 24 frames of transmission information received via the transmission path 15, performs horizontal stripe conversion in reverse to the above-mentioned transmitting section 21, and converts the information into an 8-bit control signal and a 4-bit signal. Extract 12 bits with the error correction bit of
When the error correction processing unit 26 is accessed using 2 bits as an address, an 8-bit control signal with 1-bit error correction is read out.
Transfer to.

Furthermore, when a burst error occurs, since the 8-bit configuration control signal is distributed over 8 frames, this corresponds to a 1-bit error, and the error can be corrected by the error correction processing section 26. . Also, subscriber terminal equipment 1
2 to the digital exchange 11, the control signal is processed in the same manner as described above, and the error-corrected control signal can be transmitted. Therefore, even when transmitting state information, control using a regular state transition pattern is possible.

The present invention is not limited to the above-described embodiments; for example, the control signal can have a configuration other than 8 bits, and an error correction code with a corresponding bit configuration can be generated and added. It will be a good thing if you do. Furthermore, the number of frames constituting a multiframe can be selected based on the total number of bits of the control signal and error correction code.

〔Effect of the invention〕

As explained above, the present invention provides an error correction code generation section 6 and an error correction processing section 7 in the in-office terminal device 3 and the remote terminal device 4, respectively, adds an error correction code to control information, and adds the error correction code to the control information. is transmitted in a multi-frame format, and in the conventional example in which parity bits are added, it is only for detecting transmission errors, but in the present invention, an error correction code is added. , it is possible to reliably correct a 1-bit error. Therefore, correct control information can be transmitted.

Also, since the control signal is transmitted in a multi-frame format, even if a burst error occurs, it corresponds to a 1-bit error for the control signal, and as mentioned above, 1-bit errors can be corrected. , it has the advantage of being able to transmit correct control signals. Therefore, when transmitting state information that requires a regular state transition pattern, there is almost no possibility of skipping state transitions, which has the advantage of enabling normal control. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is an explanatory diagram of a frame configuration of an embodiment of the present invention, and FIG. 4 is a control diagram of an embodiment of the present invention. 5 and 6 are explanatory diagrams of a conventional system. 1 is a digital exchange, 2 is a subscriber terminal, 3 is an in-office terminal, 4 is a remote terminal, 5 is a transmission path, 6 is an error correction code generator, and 7 is an error correction processor.

Claims (1)

[Claims] Digital exchange (1) and subscriber termination device (2) are connected by a multiplex transmission line (5) via an in-office termination device (3) and a remote termination device (4). In a transmission control system that multiplexes and transmits information and control information between subscribers, the in-office terminal device (3) and the remote terminal device (4) include an error correction code generator (6). Error correction processing unit (7)
and the digital exchange (1) and the subscriber terminal device (2) are provided, respectively.
), the error correction code generation unit (6)
The transmission is characterized in that the error correction code generated in is added and transmitted in a multi-frame format, the control information to which the error correction code is added is received, and the error correction processing section (7) performs error correction. control method.