JPH0113778B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission method for transmitting information of various data transmission speeds using one data communication line.

<Prior art> In this type of conventional data transmission method, given the amount of data to be transmitted (data transmission speed),
A line suitable for the data transmission speed was prepared, and a control circuit was configured with a data transmission control procedure tailored to the speed.

Therefore, during a series of data transmission service requests, a data transmission request may require one fixed data transmission rate at a certain point, but a different data transmission rate at another point in time. For this purpose, it is necessary to prepare multiple types of data transmission lines and data transmission control circuits from the beginning.
There were drawbacks such as reduced line usage efficiency and duplication of data transmission control circuits.

<Purpose of the invention> In order to eliminate these drawbacks, the present invention makes it possible to switch one line as appropriate during a series of services depending on the service request, and to set the data transmission speed and number of lines required at each point. The drawings will be described in detail below.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of the present invention, in which data terminal devices 110A and 110B are connected to each other through a data transmission line 105. The data terminal device 110A is the data terminal device 100A,
101A, 102A, data terminal device 110B
are data terminal equipment 100B, 101B, 102B
data terminal equipment 100A, 1
For example, 00B indicates a data transmission rate of 64Kb/s,
Data terminal equipment 101A, 101B is 32Kb/s
The data transmission speed of the data terminal equipment 102A,
It is assumed that each of the 102B has a transmission rate of 16Kb/s. Data terminal equipment 110A, 110B
For example, each data transmission line 105 side in
Data transmission control circuit 103A for procedures such as HDLC,
103B is provided. Data transmission control circuit 10
3A is switched and connected to each input/output port 106A, 107A, 108A of data terminal equipment 100A, 101A, 102A by a switch circuit 104A. The data transmission control circuit 103B controls the data terminal equipment 100B,
Each input/output port 106B of 101B, 102B,
It is switched and connected to 107B and 108B. The control units 109A and 109B each have a switch circuit 10.
6A, 106B switching and data transmission control circuit 1
Controls switching of transmission speeds of 03A and 103B.

Next, the operation of the data transmission system of the present invention will be explained using FIG.

The initial mode of the data terminal devices 110A and 110B is one of data transmission speeds of 64 Kb/s, 32 Kb/s, and 16 Kb/s, for example, 64 Kb/s.
It is assumed that this is set to .

Therefore, when data terminal devices 110A and 110B are connected for a call, the 64Kb/bit data in both terminal devices is
When the terminal devices 100A and 100B of s are activated, the switch circuits 104A and 104B are connected to the input/output ports 106 of the terminal devices 100A and 100B.
A and 106B, respectively. Therefore, the calling connection operation is performed by data terminal equipment 100A, 100.
It is accomplished through B. After that, the terminal device 100A,
If there is a request for data transmission between 100B, continue
Data transmission control circuits 103A and 103B are operated at a data transmission rate of 64 Kb/s to perform communication.

After that, in the middle of that series of services, terminal device 1
Consider a case where a request arises to cancel data transmission at 64 Kb/s between terminal devices 00A and 100B and instead perform data transmission at 32 Kb/s between terminal devices 101A and 101B. This request is transmitted to the control unit 109A through the terminal device 100A or 101A.
This information is also transmitted to the control unit 109B of the partner terminal device 110B through a transmission control procedure described later. After that, the control units 109A, 109B connect the respective switch circuits 104A, 104B to the input/output ports 107 of the terminal devices 101A, 101B.
A, 107B, and instructs the data transmission control circuits 103A, 103B to operate with a 32 Kb/s clock.

After the settings are made, the terminal devices 101A, 1
For example, between 01B and 32Kb/s speed.
Transmission control is performed using a control procedure such as HDLC, and communication is performed after a communication state is established.

Next, the terminal device 101 at this speed of 32Kb/s
During the communication between A and 101B, a new
Terminal equipment 102A, 102B at a speed of 16Kb/s
Even when a request for data transmission occurs between the two, mode switching is performed using the same procedure as above.

However, in the middle of mode switching, the terminal device 11
If an error occurs in the exchange of transmitted and received signals between 0A and 110B, and a mode mismatch occurs between both terminal devices 110A and 110B, a timer measures a certain period of time, and after that time, the Initial mode for both terminal devices (e.g. 64Kb/s mode)
Return to , and begin the process of establishing the control procedure. The control procedure for this will be described later.

In this way, communication can be performed between the terminal devices 110A and 110B, which are composed of terminal devices having a plurality of types of transmission speeds, at various transmission speeds according to service requests.

Next, there is a mode (hereinafter referred to as
64Kb/s mode, 32Kb/s mode, 16Kb/s
This section describes a method for controlling switching between modes (referred to as modes). FIGS. 2 and 3 are diagrams explaining the flow of the control method for switching the modes, with FIG. 2 showing the operation in a normal state, and FIG. 3 showing the processing control procedure in an abnormal state. In these FIGS. 2 and 3, 300 is an explanatory text indicating the operation of the terminal device 110A, 301 is a signal transmitted and received between the terminal devices 110A and 110B,
302 is an explanatory text indicating the operation of the terminal device 110B. It is also assumed that time elapses in the vertical direction of FIGS. 2 and 3 from top to bottom.

An outline of the mode switching operation during normal operation is as follows.

The terminal devices 110A and 110B are set to 64 Kb/s mode in the dormant state (initial state).
(When the terminal device 110A makes a call, it sends a calling signal to the destination terminal device 110B. Upon receiving this signal, the terminal device 110B returns a response signal to the originating terminal device 110A. Thereafter, the terminal device 100
The initial setting of 64Kb/s between A and 100B
Data transmission is performed based on, for example, an HDLC procedure at a data transmission rate of .

After that, when a request for data transmission in 36Kb/s mode using the terminal devices 101A and 101B occurs between the terminal devices 110A and 110B, the terminal device 1
During the 64 Kb/s mode using 00A and 100B, a mode change instruction signal is sent from the terminal device 100A to the terminal device 100B. Thereafter, the terminal device 110A operates a timer for a certain period of time t ₀ (for example, a certain period of time that is sufficiently longer than the elapsed time of 2α or more required for the signal to travel back and forth between the terminal devices 110A and 110B, that is, t ₀ ≫ 2α). It is monitored whether a response signal arrives from the terminal device 100B within that time. Terminal equipment 100B
When the terminal device 10 receives a mode switching signal,
0B returns a reception confirmation signal to the terminal device 100A. Further, the terminal device 100B operates a timer from that point on, and measures a certain period of time t ₁ (t ₁ >2α). If no new instruction request is received from the terminal device 100A within this time, the control unit 109B
the operating mode of the terminal device 110B through
Switch to 32Kb/s mode.

On the other hand, when the terminal device 100A receives the reception confirmation signal within the t ₀ period of the timer (in normal operation, it is received within the t ₀ period), after that a certain period of time t ₂ (t ₂ < t ₁ −α), terminal device 100
Monitor that no new signal from B arrives. Here, the new signal refers to, for example, an instruction signal other than the flag pattern in the HDLC procedure, and it is assumed that the frame synchronization of the terminal device 100B is continuously confirmed using the flag pattern.

In addition, in parallel with the measurement of the timer period t ₂ , measurement is performed for a certain period t ₃ (t ₃ > t ₁ - α), if no new signal is received from the terminal device 100B within the t ₂ period. , and when the _t3 period has passed, the terminal device 1
00A changes the mode from 64Kb/s mode to 32Kb/s
Switch to mode. By doing this, if the signal transmission and reception operations are performed normally between the terminal devices 110A and 110B, both terminal modes will be changed.
Switched to 32Kb/s mode. After that, both terminal devices 101A and 101B attempt to establish a transmission link using the HDLC procedure in 32Kb/s mode,
Data transmission will take place.

At this time, the transmission speed of the transmission line 105 is changed from 64 Kb/s data transmission to 32 Kb/s data transmission. Therefore 32Kb/s
At the start of data transmission, the terminal device 101
It is necessary to establish frame synchronization between A and 101B, but this establishment is possible with 32Kb/s HDLC.
It will be clear that this can be easily achieved by performing frame pattern detection in a procedural manner.

Furthermore, it is clear that further transition to the 16 Kb/s mode can be performed by following the same procedure as described above. If the frame pattern at this new speed cannot be detected even after a predetermined period of time and a transmission link cannot be established between the terminal devices 110A and 110B, use the initial mode (for example, 64Kb/s mode) and
Establish a transmission link in initial mode. This procedure will be described later.

Next, with reference to FIG. 3, the operation when a transmission error occurs during transmission and reception of the transmission mode switching signal will be considered. Assume that a mode change request occurs during data transmission in the 64 Kb/s mode, as in the case of FIG. However, for example, if the mode change instruction signal is incorrect,
Consider a case where the information does not reach the terminal device 110B accurately. At this time, the terminal device 110B is, for example, an HDLC
A retransmission request is sent to the terminal device 110A according to the procedure. This retransmission request is accurate to the terminal device 110A.
If the terminal device 110A does not reach the terminal device 110B, the terminal device 110A sends a retransmission request to the terminal device 110B. Furthermore, if this retransmission request does not accurately reach the terminal device 110B, the terminal device 110B sends a retransmission request to the device 110A. After repeating these steps several times, the retransmission request will eventually correctly reach either the terminal device 110A or the terminal device 110B. At this time, the case where the retransmission request does not correctly reach both terminal devices even after the above-mentioned time t ₀ has passed will be described later.

Next, consider a case where a retransmission request is correctly received at the terminal device 110A. As a result, the terminal device 110A
The terminal device 110B learns from the agreement of the HDLC procedure that this is a retransmission request for the mode change instruction signal, and sends the mode change instruction signal' again. This mode change signal' is sent to the terminal device 110B.
When received correctly (if received incorrectly, the process returns to the case of the above-mentioned retransmission request and the above procedure is repeated), a reception confirmation signal is sent to the terminal device 110A. This reception confirmation signal is sent to the terminal device 110.
If the retransmission request signal is not correctly received by A, the retransmission request signal . At this time as well, what to do if the signal is not correctly received by both terminal devices even after the t ₀ period has passed will be described later.

When the retransmission request signal is correctly received, the terminal device 110B sends out a reception confirmation signal' again.
When the terminal device 110A receives this signal correctly (if it receives it incorrectly, the result is a reception error in the previous reception confirmation signal), the terminal device 11
0A starts measuring periods t ₂ and t ₃ with a timer. Furthermore, at the same time as the reception confirmation signal ' is sent out, the terminal device 110B starts monitoring the _t1 period with a timer (monitoring no signal) and stops sending out new signals.

If something that appears to be a new signal arrives at either terminal device 110A or 110B due to transmission path noise during the no-signal monitoring period of period _t1 or period _t2 , the timer is reset and both terminals are monitored again. device 110
A and 110B exchange retransmission request signals,
Confirm that it is noise and not a new signal. It will be clear that this confirmation can be performed using, for example, an HDLC procedure. The significance of providing the t ₁ and t ₂ periods will be discussed later.

In addition, in the above explanation, if the correct signal cannot be received even after a certain period of time t ₀ , both terminal devices switch to the initial mode of 64Kb/s mode, and send the signal using the 64Kb/s transmission control procedure. In this way, we will send and receive
If control of both terminal devices can be established in the 64 Kb/s mode, switching to the desired mode can be performed.

In this way, both terminal devices 110A, 110B
It is possible to receive a correct mode switching signal and its confirmation signal between each other, and then both terminal devices 110
A and 110B can be switched to the desired mode.

The reason for providing the no-signal monitoring period at t ₁ and t ₂ in the above explanation is that after both terminal devices receive a correct signal, no new signal reaches either terminal, and both terminal devices move to switching mode. This is to confirm that _the terminal device 1
The reason why the terminal 10A did not switch the mode during that period was to prevent the new flag pattern etc. accompanying the mode switching from being mistakenly recognized as a new signal by the partner terminal device 110B. In addition, the values of each timer period above are t ₃ + α > t ₁ > t ₂ + α t ₁ > 2α t ₀ ……There is a relationship that is sufficiently large (1) compared to α, for example, t ₀ = 20α t ₁ = 4α It is possible to choose t ₂ = 2α t ₃ = 4α (2), etc.

In the above explanation, 64Kb/64Kb/
Although we have described three types of speeds: 32Kb/s, 32Kb/s, and 16Kb/s, it is clear that it can be extended to other speeds as well as to communication between terminal devices having four or more types of transmission speeds. Probably.

In addition, in FIG. 1, transmission control circuits 103A, 103
We have described the case where B is commonly switched and used for each transmission speed, but if it is not possible to commonly operate various transmission speeds with one transmission control circuit, each terminal device 100A, 100B, 101A,
It is also obvious that the transmission lines 101B, 102A, and 102B can each be provided individually, and only the transmission line can be switched by a switch.

<Effects> As explained above, in the data transmission system of the present invention, services with various data transmission speeds can be switched and transmitted as required. This method has the advantage that it requires fewer transmission lines to be secured compared to a method in which lines are prepared, and that it is possible to achieve economicalization of terminal devices by sharing transmission control circuits.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the data transmission system of the present invention, Figure 2 is a diagram explaining the flow of signal control during normal operation when switching transmission modes, and Figure 3 is when switching transmission modes. FIG. 2 is a diagram illustrating the flow of signal control when an abnormality occurs. 100A, 101A, 102A, 100B, 1
01B, 102B: Data terminal equipment, 103A,
103B: Transmission control circuit, 104A, 104B:
Switch, 105: Data transmission path, 106A, 1
07A, 108A, 106B, 107B, 108
B: Data terminal input/output port, 109A, 109
B: Control unit, 110A, 110B: Data terminal device.

Claims (1)

[Claims] 1. An input/output port that supports multiple types of data transmission speeds, a data transmission control circuit that operates at the multiple data transmission speeds, and any one input/output port among the input/output ports for the multiple data transmission speeds. and a data transmission line, the switch circuit is configured to set the data transmission speed to one of the plurality of data transmission speeds, and the data transmission control circuit is configured to set the data transmission speed to one of the plurality of data transmission speeds. A data transmission method comprising a communication control unit that controls operation at a data transmission speed.