JPH0535613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a multiplex concentrator. In particular, when the quality of the trunk line is normal, transmission is performed with the minimum delay time, and even when the quality of the trunk line deteriorates or in the event of a failure, data transmission for all terminal devices is ensured and optimal throughput is achieved. This invention relates to an improvement of a multiplexing method and device that can obtain the same.

[Description of prior art]

A general multiplexing/concentrating/demultiplexing device is installed oppositely between a terminal device and a communication control device provided at a center station via a relay line and a modulation/demodulation device.

The communication speed of data transmission performed between a communication control device and a terminal device is often made higher in order to improve line usage efficiency. However, as the communication speed increases, the data signal becomes more susceptible to line noise and the like, increasing the error rate and causing problems in data transmission.

Furthermore, when a microwave relay transmission line is used as a relay line, if the electric field strength becomes unstable due to fading or the like, erroneous data transmission is performed in bursts, causing problems in data transmission.

If these problems occur, data transmission can be continued by lowering the communication speed and reducing the error rate of the relay line. However, in this state, the line usage efficiency is poor, so it is necessary to restore the communication speed as soon as the line quality improves.

However, in systems using conventional multiplexing/concentrating/separating equipment, if the line quality of the trunk line deteriorates, this is avoided by reducing the transmission speed of the trunk line. Manual intervention was required to communicate the information and to change the speed of the multiplexing/demultiplexing device and modem. For this reason, maintenance personnel must be assigned to the center station and the opposite station, and a state of low data transmission efficiency continues for a long time, resulting in a reduction in system throughput. In addition, when the relay line is a microwave relay transmission line, unstable electric field strength may cause line deterioration immediately even if the line quality is restored, and there is a drawback that speed changes must be repeated. Ta.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multiplexing and concentrating system in which quality recovery of a trunk line is determined without human intervention and communication speeds of a modem and a multiplexing and concentrating and demultiplexing device are automatically changed.

[Key points of the invention]

The present invention provides a multiplexing and concentrating system that includes a multiplexing and demultiplexing device that multiplexes and demultiplexes a large number of low-speed digital signals into one high-speed digital signal, and a modulation and demodulation device that transmits and receives the high-speed digital signal to and from an opposing station. The concentrator and demultiplexer includes a monitoring means for monitoring the transmission quality with the opposite station using an error control code, and a first control frame _C1 for converting the clock speed based on the output of the monitoring means. means for changing the clock speed of the high-speed digital signal after transmitting it to the opposite station for a predetermined time _t2 , and transmitting a second control frame _C3 for training at the new clock speed; Response frame _C4 from the opposite station to the second control frame _C3 thus transmitted
means for starting data transmission by receiving the data for a second predetermined time _t3 and checking the operation; and means for monitoring the clock speed for a predetermined time _t4 in a state where the clock speed is set to a low value, and detecting that the transmission quality has been recovered. is detected, a predetermined fourth control frame C5 is transmitted at a high clock speed, a response frame _C6 to the fourth control frame is received from the opposite station, and this response frame is transmitted at a _high clock speed. means for changing the clock speed to a high speed after a third predetermined time _t5 has elapsed after transmitting the clock speed to the opposite _station ; means for starting data transmission by receiving a response frame _C8 from the station for a second predetermined time _t3 and confirming operation;
means for timing said second predetermined time _t3 from being controlled to transmit at a high clock speed;
If the monitoring means detects deterioration in the transmission quality again within this predetermined time, it prohibits the operation of the means for changing the clock speed to the high speed and the means for starting data transmission at the high clock speed, and also switches to manual mode. It is characterized by comprising a means for switching.

[Explanation based on examples]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a block diagram showing details of the multiplexing/concentrating/separating devices 3 and 7 shown in FIG.

First, the configuration and connections of this embodiment will be explained based on FIGS. 1 and 2.

This embodiment system includes a communication control device 1, low-speed lines 2-1 to 2-n and 8-1 to 8-n, multiplexing and demultiplexing devices 3 and 7, modem devices 4 and 6, and trunk lines. 5 and terminal devices 9-1 to 9-n
The multiplexing/concentrating/separating devices 3 and 7 are comprised of low-speed line level conversion circuits 10-1 to 10-1.
10-n and low-speed line transmitting/receiving circuits 11-1 to 1
1-n, integrated multiplex circuit 12, and switching circuit 13
, a transmitting/receiving circuit 14, a data frame level conversion circuit (hereinafter referred to as a data level conversion circuit) 15, a speed switching signal level conversion circuit (hereinafter referred to as a signal level conversion circuit) 16,
It is composed of a control circuit 17 and a frame monitoring circuit 18.

As shown in FIG. 1, each of the n inputs and outputs of the communication control device 1 is connected to each of the n first inputs and outputs of the multiplexing concentrator and demultiplexer 3 via low-speed lines 2-1 to 2-n. The second input/output of the multiplexing/concentrating/separating device 3 is connected to the first input/output of the modem 4, and the second input/output of the modem 4 is connected to the demodulator 6 via the trunk line 5. The second input/output of the modem 6 is connected to the first input/output of the multiplexing concentrator 7, and the n second inputs and outputs of the multiplexing concentrator 7 are connected to the first input/output of the modem 6. Each of the outputs is sent to the terminal devices 9-1 through 8-n via low-speed lines 8-1 through 8-n.
It is connected to each input/output of 9-n.

FIG. 2 is a block diagram of each of the multiplexing concentrators 3 and 7. As shown in FIG. As shown in this Figure 2,
The second input/output of the low-speed line level conversion circuits 10-1 to 10-n are respectively connected to the transmitting/receiving circuits 11-1 to 11-n.
connected to each of the first input and output of 11-n,
Each of the second input/outputs of the transmitting/receiving circuits 11-1 to 11-n is connected to each of the n first input/outputs of the line concentrating multiplexing circuit 12, and the line concentrating multiplexing circuit 12
The second output of the switching circuit 13 is connected to the first input of the switching circuit 13, the output of the switching circuit 13 is connected to the first input of the transmitting/receiving circuit 14, and the first output of the transmitting/receiving circuit 14 is connected to the first input of the switching circuit 13. connected to the first input. A second output of the data level converter circuit 15 is connected to a second input of the transmitter/receiver circuit 14 , and a second output of the transmitter/receiver circuit 14 is connected to a second input of the line concentrator/multiplexer circuit 12 . The second output of the transmitter/receiver circuit 14 is also connected to the input of the frame monitoring circuit 18 , the output of the frame monitoring circuit 18 is connected to the input of the control circuit 17 , and the first output of the control circuit 17 is connected to the input of the switching circuit 13 . , a second output of the control circuit 17 is connected to a third input of the switching circuit 13 , a third output of the control circuit 17 is connected to a third input of the concentrator multiplexing circuit 12 , It is connected to the third input of the transmitting/receiving circuit 14 and the input of the signal level conversion circuit 16, respectively.

Furthermore, if a station consisting of a multiplexing concentrator 3 and a modem 4 is called station A, and a station consisting of a multiplexing concentrator 7 and a modem 6 is called a station B, the low speed of station A is Line level conversion circuit 10-1
Each of the first input/outputs of ~10-n is connected to each of the n input/outputs of the communication control device 1, and the second input/output of the data level conversion circuit 15 of station A is connected to the first input/output of the modem device 4. connected to the input/output of station A
The output of the signal level conversion circuit 16 is connected to the second input of the modem 4, and the first input/output of the low-speed line level conversion circuits 10-1 to 10-n of station B are connected to the terminal device 9. -1 to 9-n, and the second input/output of the data level conversion circuit 15 of station B is connected to the first input/output of the modulation/demodulation device 6. The output of the conversion circuit 16 is connected to a second input of the modem 6.

Next, the operation of this embodiment will be explained based on FIGS. 3 to 6.

Here, FIG. 3 shows the structure of a data frame used for data transmission between the multiplexing concentrators 3 and 7, and FIG. 3A shows the data character section 20 corresponding to the transmission data. and the same B
is the control character part 2 corresponding to the control frame
It has 2.

FIG. 4 is a time chart showing the operation of the system of this embodiment, where 1 and 1' represent the operation of the transmitting section of station A, 2 and 2' represent the operation of the receiving section of station A, and 3 and 3' represent the operation of the transmitter of station B, and 4
and 4' represent the operation of the receiving section of station B. Fourth
In the figure, the time axis T is such that the right end of 1 and the left end of 1' are
The right end of 2 and the left end of 2' are joined, the right end of 3 and the left end of 3' are joined, and the right end of 4 and the left end of 4' are joined, and they are not shown separated in the figure. There is. Furthermore, in the time periods divided by the codes α and β, the transmission speeds of this embodiment method are “α” and “β”, respectively, and the codes t ₁ to t
Each t ₅ indicates the time length of the time interval to which this symbol is attached. Further, symbols I and C ₁ to C ₆ indicate transmission data of frame configurations A and B in FIG. 3.

Further, FIGS. 5 and 6 are diagrams showing the transition of data transmission states performed between the multiplexing/concentrating/demultiplexing devices 3 and 7. FIG.

First, based on FIGS. 1, 2, 3, and 4, the operation of each part constituting the system of this embodiment in connection with switching the transmission speed will be explained.

As shown in FIG. 1, data from a communication control device 1 is input to a multiplexing/concentrating/separating device 3 via low-speed lines 2-1 to 2-n, concentrating/multiplexing the data in this device 3, and transmitting data to a modem/modulator. 4 and 6 and the relay line 5 to the multiplexing line demultiplexing device 7 of the opposite station, separated into low-speed lines 8-1 to 8-n, and transmitted to terminal devices 9-1 to 9-n. . On the other hand, data from the terminal devices 9-1 to 9-n is transmitted through the low-speed line 8-
1 to 8-n to the multiplexing/concentrating/separating device 7, concentrating and multiplexing the signals in this device, and inputting the signals to the multiplexing/concentrating/separating device 7 of the opposing station via the modulation/demodulation devices 4, 6 and the relay line 5. The signals are separated into low-speed lines 2-1 to 2-n and transmitted to the communication control device 1. In this way, data transmission between the terminal devices 9-1 to 9-n and the communication control device 1 is performed mutually.

Next, as shown in FIG. 2, the low-speed data from the communication control device 1 or the terminal devices 9-1 to 9-n is transferred to the low-speed circuit level conversion circuits 10-1 to 10-n.
The level is converted by n, and the transmitting/receiving circuits 11-1 to 11
- After being serial-parallel converted by n, the line concentrator multiplexing circuit 1
2 and is multiplexed by this circuit. After passing through the switching circuit 13, the multiplexed data frame is subjected to parallel-to-serial conversion in the transmitting/receiving circuit 14, and further level-converted in the data level conversion circuit 15, and then provided to the modulation/demodulation device 4 or 6.

On the other hand, the data frame input to the modulation/demodulation device 6 or 4 is level-converted by a level conversion circuit 15 and input to the transmitting/receiving circuit 14, where it is serial-to-parallel converted and then separated by a line concentrator/demodulator 12 to support low-speed lines. be done. The separated low-speed data is parallel-to-serial converted by the transmitting/receiving circuits 11-1 to 11-n of each low-speed line, and then sent to the low-speed line level conversion circuit 10.
-1 to 10-n are level-converted and sent to a low-speed line.

Now, in station A, the output of the transmitting/receiving circuit 14 is given to the line concentrator multiplexing circuit 12 and also to the frame monitoring circuit 18. In the frame monitoring circuit 18, a cyclic code check calculation is performed on the characters of the data character section 20 included in the received data frame, and the presence or absence of data errors is detected. This calculation requires, for example, CRC−
In the case of the CCITT method, the generator polynomial X ¹⁶ +X ¹² +
X ⁵ +1 is used.

When the frame monitoring circuit 18 of station A detects that a frame error has continued in the received data frame for a certain period of time "t ₁ " or more, as shown in FIG. 2, a deterioration signal is output from the frame monitoring circuit 18 to the control circuit 17. When this deterioration signal is received by the control circuit 17, the control circuit 17 outputs a switching signal to the switching circuit 13 and also sends out the control frame _C1 . Continuing, Figure 4 1
As shown in FIG.
A control frame C ₁ is transmitted in place of the data signal from the line concentrator multiplexer 12 .

When this control frame C ₁ is received by the frame monitoring circuit 18 of the opposite station B, the frame monitoring circuit 18 sends it to the control circuit 17 as shown in FIG.
A frame response signal is sent. When this frame response signal is received by the control circuit 17, a switching signal is outputted from the control circuit 17 to the switching circuit 13, and a control frame _C2 is sent from the control circuit 17 to the transmitting/receiving circuit 14. It is further transmitted to station A as shown in FIG.

On the other hand, when a certain period of time "t ₂ " has elapsed since the start of transmission of the control frame C ₁ at station A, the control circuit 17 of station A controls the transmitting/receiving circuit 14, line concentrator multiplexing circuit 12, and signal level converting circuit 16. A speed switching signal is sent to each of them, and further, a speed switching signal is sent from the signal level conversion circuit 16 to the modulation/demodulation device 4, and the transmission speed is switched from "α" to "β". Also, at the opposite station B, the control frame
When C ₁ is normally received for a certain period of time “t ₂ ” or more, the control circuit 17 of the opposite station B sends the signal to the transmitter/receiver circuit 1
4. A speed switching signal is sent to each of the line concentrator multiplexing circuit 12 and the signal level conversion circuit 16,
Further, a speed switching signal is sent from the signal level conversion circuit 16 to the modulation/demodulation device 6, and the transmission speed is switched from "α" to "β".

Thereafter, as shown in FIG. 4, a control frame C3 is sent from the control circuit 17 of the station A to the control circuit ₁₇ of the opposing station B at the transmission rate "β". When this control frame _C3 is received by the frame monitoring circuit 18 of the opposite station B, a frame response signal is sent from the frame monitoring circuit 18 to the control circuit 17, as shown in FIG. When this frame response signal is received by the control circuit 17, the control circuit 1
Control frame _C4 is sent from station A to station A as shown in FIG.

When this control frame _C4 is received by the control circuit ₁₇ of station A, as shown in FIG. ₄ is received for a certain period of time "t ₃ ", a switching signal is sent from the control circuit 17 to the switching circuit 13 as shown in FIG. A data frame from the concentrator/multiplexer 12 is sent out instead of the control frame _C4 from the control frame C4.

When the control frame C ₄ is received for a certain period "t ₃ " at the opposite station B, a switching signal is sent from the control circuit 17 to the switching circuit 13 as shown in FIG. From transmitter/receiver circuit 1
4, a data frame from the line concentrator and multiplexer 12 is sent out in place of the control frame _C4 from the control circuit 17.

Next, while data transmission is being carried out at speed "β", the frame monitoring circuit 18 of station A detects errors in the received data for a certain period of time "t ₄ ", as shown in FIG. 4 2 and 2'. If not detected, a deterioration cancellation signal is sent from the frame monitoring circuit 18 to the control circuit 17, as shown in FIG. 4 1'. From this control circuit 17, a switching signal is output to the switching circuit 13, and as shown in FIG.
As shown in , the control frame _C5 is sent to the transmitter/receiver circuit 1.
4, and further transmitted to the opposing station B.

When this control frame _C5 is received by the frame monitoring circuit 18 of the opposite station B, a control frame response signal is sent from the frame monitoring circuit 18 to the control circuit 17, as shown in FIG. 4'. In response to this frame response signal, a control frame _C6 is sent from the control circuit 17 to the transmitting/receiving circuit 14, and further transmitted to station A.

When this control frame _C6 is received by the frame monitoring circuit 18 of station A, the frame monitoring circuit 18 sends it to the control circuit 1 as shown in FIG.
A frame response signal is sent at 7. In response to this control frame response signal, a control frame _C6 is sent from the control circuit 17 to the transmitting/receiving circuit 14, and further transmitted to station B.

When this control frame C ₆ is received by the frame monitoring circuit 18 of the opposite station B, a deterioration cancellation signal is sent from the frame monitoring circuit 18 to the control circuit 17. In response to this deterioration cancellation signal, a speed switching signal is sent from the control circuit 17 to the line concentrator multiplexing circuit 12, the transmitting/receiving circuit 14, and the level converting circuit 16, and the transmission speed is switched from "β" to "α".

Furthermore, when a certain period of time " _t5 " has elapsed after the control frame _C6 was sent to the opposite station B, the transmission rate at the station A is also switched from "β" to "α" by the same operation as the opposite station B. It will be done. Continuing on from this, the fourth
As shown in FIG. 1', a control frame _C7 is sent from the control circuit 17 of station A to the transmitter/receiver circuit 14, and further transmitted to the opposing station B.

When this control frame _C7 is received by the frame monitoring circuit 18 of the opposite station B, a frame response signal is sent from the frame monitoring circuit 18 to the control circuit 17 as shown in FIG. 4'. In response to this frame response signal, a control frame _C8 is sent from the control circuit 17 to the transmitting/receiving circuit 14, and is transmitted to station A as shown in FIG. 4, 3'.

When this control frame _C8 is received by the frame monitoring circuit 18 of station A, the frame monitoring circuit 18 sends it to the control circuit 17 as shown in FIG.
A control frame response signal is sent. In response to this control frame response signal, a control frame _C8 is sent from the control circuit 17 to the transmitting/receiving circuit 14, and the fourth
The signal is transmitted to the opposing station B as shown in FIG. 1'.

On the other hand, when the control frame C ₈ is received at station A for a certain period of time "t ₃ ", as shown in FIG.
A switching signal is sent out, and instead of the control frame from the control circuit 17, a data frame is sent from the line concentrator multiplexing circuit 12 to the transmitting/receiving circuit 14.

Further, when the control frame C ₈ is received at the B station for a certain period of time "t ₃ ", as shown in FIG.
A switching signal is sent out, and instead of the control frame from the control circuit 17, a data frame is sent from the line concentrator multiplexing circuit 12 to the transmitting/receiving circuit 14.

Next, the data transmission operation performed between the multiplexing/concentrating/separating devices 3 and 7 will be explained based on the state transition diagrams of FIGS. 5 and 6.

Reference numeral 24 in FIG. 5 indicates that the trunk line 5 is in a normal data transmission state, and in this state data transmission is performed at the transmission rate "α". Here, if the quality deterioration of the relay line 5 continues for a certain period of time "t ₁ " or more, the state shifts to the first operational training state 25 via the route 28. In this state 25, the transmission rate “α” is the transmission rate “β”
has been changed to. When the data transmission operation is confirmed at the speed "β" for a certain period "t ₃ " in this state 25, the state shifts to the first abnormal data transmission state 26 via the route 29. If no error occurs in data transmission for a certain period of time "t ₄ " in this state 26, a transition is made to a second motion training state 27 via route 30. In this state 27, the transmission rate "β" has been restored to the transmission rate "α". When it is confirmed in this state 27 that the data transmission operation at the transmission rate "α" is normal for a certain period "t ₃ ", the data transmission state 24 returns to the normal data transmission state 24 via the route 31. On the other hand, if the normality of the data transmission operation is not confirmed by the speed "α" for a certain period of time "t ₃ ", the state shifts to the first operation training state 25 via the route 32. Next, as described above, the data transmission state 26 at the time of the first abnormality is passed to the second operation training state 27, and if the normality of the data transmission operation in this state 27 is confirmed, the data transmission operation returns to the normal state. The state returns to the data transmission state 24 at the time. However, if the normality of data transmission operation is not confirmed at this stage,
This will be explained based on the state transition diagram shown in FIG.

In this case, the state moves to the third motion training state 34 via route 33. This state 3
4, the speed "α" is changed to the speed "β". When the normality of the data transmission operation at the speed "β" is confirmed for a certain period "t ₃ " in this state 34, the second abnormal data transmission state 36 at the speed "β" is performed via the route 35. to move to.

In this state 36, it is manually confirmed that the quality deterioration of the trunk line 5 has been restored. Next, when the switch is manually operated, the state shifts to a fourth motion training state 38 via route 37. When the data transmission operation is confirmed at the speed "α" for a certain period " _t3 " in this state 38, the normal transmission state 24 is transmitted via the route 39.
to return to. On the other hand, if the data transmission operation is not confirmed at the speed "α" for a certain period "t ₃ ", the state shifts to the third training state 34 via the route 40. Subsequently, the above-described state transition is repeated.

〔Effect of the invention〕

As described above, the present invention automatically lowers the transmission speed to achieve transmission with a low error rate when the error rate of the trunk line temporarily increases, and also enables the relay line to recover. (1) There is no need for human intervention to contact the opposite station, change the speed of the multiplexer/demultiplexer and modem, and restore data transmission. (2) Communication with low error rate can be achieved even when trunk line quality deteriorates; (3) Even when trunk line quality is temporarily unstable,
This has the effect of obtaining optimal throughput.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a block diagram showing a multiplexing concentrator/separator according to the present invention. FIG. 3 is a configuration diagram of a data frame used in data transmission according to the present invention. FIG. 4 is a time chart explaining the operation of the system according to the embodiment of the present invention. FIGS. 5 and 6 are state transition diagrams showing data transmission states of the present invention. 1... Communication control device, 2-1 to 2-n, 8-1
~8-n...Low speed line, 3,7...Multiplexing/demultiplexing device, 4,6...Modulation/demodulation device, 5...Relay line, 9-1~9-n...Terminal device, 10-1~ 1
0-n...Level conversion circuit for low-speed line, 11-1
~11-n...Low-speed line transmitting/receiving circuit, 12...
Concentrator multiplexing circuit, 13...Switching circuit, 14...Transmitting/receiving circuit, 15...Data level conversion circuit, 1
6... Signal level conversion circuit, 17... Control circuit, 18... Frame monitoring circuit, 19... Flag character, 20... Data character, 21,
23...Frame check character, 22...
control character.

Claims (1)

[Scope of Claims] 1. A multiplexing and concentrating system comprising a multiplexing and demultiplexing device that multiplexes and demultiplexes a large number of low-speed digital signals into one high-speed digital signal, and a modulation and demodulation device that transmits and receives the high-speed digital signal to and from an opposing station. The multiplexing/concentrating/separating device includes a monitoring means for monitoring the transmission quality with the opposite station using an error control code, and a first control frame C for converting the clock speed based on the output of the monitoring means. ₁ to the opposite station for a first predetermined time _t2 , and then changing the clock speed of the high-speed digital signal to send out a second control frame _C3 for training at the new clock speed; means for starting data transmission by receiving a response frame _C4 from the opposite station for a second predetermined time _t3 in response to the second control frame _C3 transmitted at the clock speed and confirming operation; , when the monitoring means detects that the transmission quality has been restored for a certain period of time _t4 while the clock speed is set low, a predetermined fourth control frame _C5 is transmitted at a high clock speed. , receives a response frame C ₆ to the fourth control frame from the opposite station, transmits this response frame to the opposite station, and then changes to a high clock speed after a third predetermined time t ₅ has elapsed. and by receiving for a second predetermined time _t3 a response frame _C8 from the opposite station in response to the fifth training control frame _C7 sent after changing the clock speed to a high clock speed to confirm the operation. means for starting data transmission; means for timing said second predetermined time _t3 after being controlled to transmit at a high clock speed; A multiplexing line concentration system characterized by comprising means for changing the clock speed to the high speed when deterioration is detected, and means for prohibiting the operation of the means for starting data transmission at the high clock speed and switching to manual mode. .