JPH0548670A - Isdn terminal equipment - Google Patents

Abstract

PURPOSE:To effectively transmit data by setting a transmission mode with a smaller communication cost from between the line exchange mode and the packet exchange mode. CONSTITUTION:The picture of a transmission original set in a scanner is read and picture information obtained by this is stored 102 in a picture storing device. Communication time in the line exchange mode is calculated based on relation between transmission speed in the line exchange mode and the information quantity of stored picture information to multiply the communication cost so that the communication cost CA in the line exchange mode is calculated 103. Next, a packet number needed for transmitting picture information is calculated from relation between the information quantity of stored picture information and a max. packet size usable in the packet exchange mode to multiply the communication cost so that the communication cost CB in the packet exchange mode is calculated 104. Here, a destination terminal is called 105, 106 and 110 by the transmission mode with the smaller communication cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ISDN terminal device having a circuit switching mode information channel transmission procedure function and a packet switching mode information channel transmission procedure function.

[0002]

2. Description of the Related Art One ISDN basic interface has
One signal channel and two information channels are multiplexed, and there are two types of data transmission modes using the information channel: a circuit switching mode and a packet switching mode. By making a call operation by designating the transmission mode of, data transmission in a desired transmission mode can be performed.

Generally, data transmission using the circuit switching mode is suitable for transmitting a large amount of data with high density. On the other hand, data transmission using the packet switching mode is suitable for data transmission in which the amount of data to be transmitted is relatively small and real-time performance is not required, for example, when interactive data transmission is performed.

[0004]

In this way, the IS
Since there are two types of transmission modes for data transmission using DN, which transmission mode is selected is left to the user who specifies the data transmission, and efficient data transmission may not be possible. It was

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ISDN terminal device capable of efficient data transmission.

[0006]

The present invention comprises a first cost calculating means for calculating a transmission time in a circuit switching mode, a second cost calculating means for calculating a transmission time in a packet switching mode, and a first cost calculating means. The control unit selects the transmission mode corresponding to the smaller one of the calculation results of the first cost calculation unit and the second calculation unit and starts the call setting operation in the transmission mode. Further, when the information channel is not established in the transmission mode initially set, the control means recalls the destination in the other transmission mode.

[0007]

Therefore, the transmission mode with the smaller communication cost is set between the circuit switching mode and the packet switching mode, so that efficient data transmission can be performed. Also. If the other terminal does not have the first selected transmission mode and the first call setup operation does not end normally, the call is re-established in the other transmission mode, ensuring reliable data transmission. It can be performed.

[0008]

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

FIG. 1 shows a group 4 facsimile apparatus according to an embodiment of the present invention.

In FIG. 1, a control unit 1 mainly performs control processing of each unit of the group 4 facsimile apparatus, and a system memory 2 executes a control processing program executed by the control unit 1 and a processing program. In addition to storing various kinds of data necessary for the operation, the work area of the control unit 1 is configured, and the parameter memory 3 is for storing various kinds of information unique to the group 4 facsimile machine. ..

The scanner 4 is for reading an original image at a predetermined resolution, the plotter 5 is for recording and outputting an image at a predetermined resolution, and the operation display unit 6 is a facsimile device. For operation,
It consists of various operation keys and various indicators.

The encoding / decoding unit 7 is for encoding and compressing the image signal and for decoding the encoded and compressed image information into the original image signal. The image storage device 8 is
This is for storing image information in a coded and compressed state.

The ISDN interface circuit 9 connects the group 4 facsimile apparatus to the ISDN and integrates the signal processing function of the layer 1 and the D channel (signal channel) signal and the two B channel (information channel) signals. Since the D channel transmission control unit 10 has a separation function, the D channel transmission control unit 10 performs ISD such as call setup / call release procedure processing.
This is for executing signal processing on the N D channel, and the B channel transmission control units 11 and 12 are for realizing the group 4 facsimile transmission procedure function performed on the B channel. In addition, the D channel transmission control unit 10
Also has a call control function in the packet switching mode, and
The channel transmission control units 11 and 12 also have a packet switching mode transmission function.

These control unit 1, system memory 2,
Parameter memory 3, scanner 4, plotter 5, operation display unit 6, encoding / decoding unit 7, image storage device 8, D channel transmission control unit, and B channel transmission control units 11 and 1.
2 is connected to the system bus 13, and data is exchanged between these respective elements mainly via the system bus 13.

FIG. 2 shows an example of a series of procedures from the calling operation to the call releasing operation in the circuit switching mode of the group 4 facsimile machine.

First, the calling terminal sends a call setup message SETUP destined to the intended destination terminal to the ISDN to request call setup with the called terminal, and the ISDN sends a call setup message to the designated called terminal. Send SETUP to make a call.

When the called terminal responds to the incoming call, it sends a response message CONN to the ISDN, and the ISDN sends a response message CONN to the calling terminal to notify that the called terminal has accepted the call and to notify the call setting status. A call setting acceptance message CALL_PROC for sending to the calling terminal.

The ISDN also sends a response confirmation message CONN_ACK to the destination terminal to confirm the response of the destination terminal, at which point an information channel (B channel) for data transmission between the source terminal and the destination terminal. , Which causes the originating and terminating terminals to initiate transmission procedures on the B channel.

First, the calling terminal sends a command SABM to request the setting of the link layer, and the called terminal responds with a response UA, whereby the link layer is set.

Then, the calling terminal sends a signal SQ in order to set up the network layer end to end,
The destination terminal sends a signal SF to accept it,
Then, the calling terminal sends a signal CR for a calling request, and the called terminal responds with a signal CA to accept the call, whereby the network layer is set.

Next, the calling terminal sends a signal TCR to set the transport layer, and the called terminal sends a signal TCA to accept it, whereby the transport layer is set.

Then, the calling terminal sends a session start command CSS in order to set up a session layer connection, and the called terminal responds with a session start acknowledge response RSSP, whereby the session layer is started. ..

Next, the calling terminal sends a document function list command CDCL to negotiate the transmission function to be used, and the called terminal sends a document function list affirmative response RDCLP, whereby the reception capability is confirmed. Adjustments are made.

When the preparation for image information transmission is completed in this manner, the calling terminal transmits image information for one document using a plurality of document user information command CDUIs following the document start command CDS. When the transmission is completed, the document end command CDE is sent to notify the end of the image information of one document. In addition, in the document start command CDS, in order to distinguish the document to be transmitted,
The document reference number is added.

The destination terminal is the document end command CD
When E is received, a document end affirmative response RDEP indicating that the document reception is normally completed is transmitted.

When the transmission of the image information for one document is completed in this way, the calling terminal sends the session end command CSE.
And the destination terminal sends a session end affirmative response RS
Send EP to release the session layer connection.

Next, the calling terminal sends the command DISC of the link layer and the called terminal sends the response UA, whereby the link layer is released.

In this way, when the link on the B channel is released, the calling terminal sends the disconnect message DISC to I
Send to SDN to initiate D channel release procedure, IS
The DN sends a disconnection message DISC to the destination terminal to notify the restoration of the information channel.

As a result, when the called terminal responds to the ISDN with a release message REL notifying the completion of the channel disconnection, the release message REL is sent from the ISDN to the calling terminal. When the channel release is completed, the calling terminal sends a release complete message REL_COMP to the ISDN to notify it, whereby the ISDN sends a release complete message REL_COMP to the destination terminal, thereby ending the call release. ..

In this way, the image information is transmitted from the calling terminal to the called terminal.

FIG. 3 shows an example of a transmission procedure when the group 4 facsimile apparatus transmits data in the packet switching mode.

First, the calling terminal ISDN sends a call setup message SETUP specifying the transfer mode as the packet mode.
To send to.

As a result, the ISDN responds to the calling terminal with a call setting acceptance message CALL_PROC and sends a response message CONN to the calling terminal to set a communication path of an information channel with the calling terminal.

In this way, when the information channel is allocated, the calling terminal sends the calling packet CR to the ISDN with the ISDN address of the called terminal set as the destination address.

As a result, the ISDN recognizes the destination terminal and sends a call setup message SETUP to the destination terminal with the use channel set to the B or D channel and the communication mode set to the packet mode. It is sent to the destination terminal.

Thus, when the called terminal responds with the response message CONN in which the used channel is set to the B channel, the ISDN sets the B channel to the communication path and sends the called packet CN to the called terminal.

As a result, when the incoming call acceptance packet CA is returned from the called terminal, the ISDN sends a connection completion packet CC to the calling terminal, whereby a packet communication path is established between the calling terminal and the called terminal. Is set.

After that, the data transfer phase is executed according to the transmission procedure defined between the calling terminal and the called terminal, and the transmission file is sent from the calling terminal to the called terminal. In this data transfer phase, data transmission procedure signals of layer 4 and above are exchanged using the data packet DT.

That is, in this case, first, in the same manner as the data transmission procedure of the layer 4 or higher in the circuit switching mode described above,
The calling terminal sends a signal TCR to set the transport layer, and the called terminal sends a signal TCA to accept it, whereby the transport layer is set.

Then, the calling terminal sends a session start command CSS to set the session layer connection, and the called terminal responds with a session start acknowledge response RSSP, whereby the session layer is started. ..

Next, the calling terminal sends a document function list command CDCL to negotiate the transmission function to be used, and the called terminal sends a document function list affirmative response RDCLP, whereby the reception capability is confirmed. Adjustments are made.

In this way, when the preparation for image information transmission is completed, the calling terminal transmits the image information for one document using a plurality of document user information commands CDUI after the document start command CDS, When the transmission is completed, the document end command CDE is sent to notify the end of the image information of one document.

The destination terminal is the document end command CD
When E is received, a document end affirmative response RDEP indicating that the document reception is normally completed is transmitted.

When the transmission of the image information for one document is completed in this way, the calling terminal sends the session end command CSE.
And the destination terminal sends a session end affirmative response RS
Send EP to release the session layer connection.

When the data transfer phase ends, the calling terminal sends a restoration request packet CQ to the ISDN to request the release of the communication path with the called terminal, and the ISD
N sends a disconnection instruction CI packet to the destination terminal.

As a result, the destination terminal sends the disconnection confirmation packet CF to the ISDN to release the communication path, and the ISDN sends the restoration confirmation packet CF to the calling terminal.

In this way, when the packet communication path between the calling terminal and the called terminal and the communication path between the calling terminal and the ISDN are opened, the calling terminal then sends the disconnection message DISC. To the ISDN to request the release of the information channel, which causes the ISDN to send a disconnect message DISC to the destination terminal to signal the restoration of the information channel.

As a result, the destination terminal sends the release message RE.
When L is responded to ISDN, ISDN sends a release message REL to the calling terminal. The calling terminal sends a release complete message REL_COMP to the ISDN, which causes the ISDN to release the release complete message REL_COMP.
To the destination terminal, whereby the information channel established between the source terminal and the destination terminal is completely released.

In this way, an information channel is set between the calling terminal and the called terminal, a packet communication path is set on the information channel, and packet mode data transmission is performed using the packet communication path. .. Then, when the data transmission is completed, the packet communication path and the information channel are sequentially released.

Now, each message for call setup is, as shown in FIG. 4A, a protocol identifier for identifying a protocol specification (format, sequence, etc.) that defines a layer 3 call control message, and its message. Call number to identify which call is involved in each message, message type to identify the content of each message, mandatory information element that is always added to each message, and required for each message It consists of additional information elements added according to. In addition,
0, 1, or a plurality of essential information elements are set according to the message type, and 0, 1, or a plurality of additional information elements are arranged according to the situation.

The call setup message SETUP is, as shown in FIG. 7B, a "transmission capability" as an essential information element.
And the additional information element is, for example, "calling number",
It has information elements such as "Called Number", "Lower Layer Consistency", and "Higher Layer Consistency".

The outline of these information elements will be described.

The "transfer capability" information element is an information transfer indicating whether the content of information to be transmitted is voice, unrestricted digital information, restricted digital information, 3.1 KHz audio, 7 KHz audio, or video. Capability, transfer mode indicating whether the switching function used is circuit switching or packet switching, information transfer speed indicating information transfer speed, information indicating information transfer mode, and information indicating user information protocol, etc. Consists of.

The "calling number" information element is the ISDN of the calling terminal.
Represents the address (number), and the "Called party number" information element is
Indicates the ISDN address of the destination terminal.

The "lower layer compatibility" information element is for use in checking the communicability with the partner terminal, and its basic contents are the same as the "transmission capability" information element. Furthermore, this "lower layer compatibility" information element contains more detailed content.

The "higher layer compatibility" information element is used for consistency check with the partner terminal, and includes group 2 / group 3 facsimile, group 4 facsimile, mixed mode, teletex, videotex,
Displays whether a telex or message handling system is provided as a terminal function.

For example, in the procedure example shown in FIG. 3, the call setup message SETUP sent when the calling terminal activates the packet processing device PH is the packet transfer mode in the transfer mode information of the "transfer capability" information element. Is set, and default values are used for other information contents.

FIG. 5 shows an example of processing performed by the group 4 facsimile apparatus shown in FIG. 1 when making a call.

First, the designated destination ISDN number is stored (step 101), the image of the transmission original set in the scanner 4 is read, and the image signal obtained thereby is encoded by the encoding / decoding unit 7. The image information obtained by compression is stored in the image storage device 8 (process 102).

Then, the transmission rate in the circuit switching mode,
The communication time in the circuit switching mode is calculated based on the relationship with the amount of accumulated image information, and the communication cost CA in the circuit switching mode is calculated by multiplying the communication time by the communication cost per unit time. (Process 103).

Next, the number of packets required to transmit the image information is calculated from the relationship between the information amount of the accumulated image information and the maximum packet size that can be used in the packet switching mode. The communication cost CB in the packet switching mode is calculated by multiplying the communication cost per packet (process 104).

Communication cost CA calculated in this way
, Is determined to be equal to or lower than the communication cost CB (decision 105). When the communication cost CA in the circuit switching mode is small and the result of determination 105 is YES, the destination is called in the circuit switching mode using the stored ISDN number of the other party (process 106).

At this time, when the call setup procedure processing is normally executed and the B channel is established (the result of judgment 107 is YES), the above-mentioned transmission procedure in the circuit switching mode is executed and the image storage device 8 is executed. When the image information of the stored transmission image is transmitted to the partner terminal (process 108) and the image information transmission operation is completed, a call release operation is performed (process 109) and a series of transmission operations is completed.

On the other hand, when the communication cost CA in the packet switching mode is small and the result of the judgment 105 is NO, the destination is called in the packet switching mode using the stored ISDN number of the destination ( Process 110).

At this time, when the call setting procedure processing is normally executed and the B channel is established (the result of the judgment 111 is YES), the above-mentioned packet switching mode transmission procedure is executed and the image storage device 8 is executed. The image information of the stored transmission image is transmitted to the partner terminal (process 112), and when the image information transmission operation ends, the call release operation is performed (process 11).
3) Then, a series of transmission operations is completed.

When the call setting operation is first performed in the circuit switching mode and the B channel is not established with the other party and the result of determination 107 is NO, the calling operation is terminated. Then, the process shifts to processing 110, and the other terminal is called again in the packet switching mode.

When the call setting operation is first performed in the packet switching mode and the B channel is not established with the other party and the result of determination 111 is NO, the call originating operation is terminated. Then, the processing shifts to the processing 106, and the other terminal is called again in the circuit switching mode.

Therefore, in this embodiment, based on the information amount of the image information formed by reading the image of the transmission original set on the scanner 4, the communication cost in the line switching mode or the packet switching mode is higher. Since the small transmission mode is selected, the cost required for image information transmission can be reduced.

Further, when the B channel is not established with the partner terminal in the initially set transmission mode, the same destination is called again in another transmission mode. The transmission mode that is available can be used accurately.

By the way, although the communication cost is calculated only from the amount of information in the above-mentioned embodiment, it is preferable to calculate the total communication cost in consideration of the communication cost required for the transmission procedure on the B channel. ..

For example, in the packet switching mode, B
When the data packet DT of the channel is charged and the data packet DT received from the called terminal is also charged to the calling terminal side, the communication cost is increased by the number of the transmission procedure signals of Layer 4 or higher. ..

In the above-described embodiment, the case where the present invention is applied to the group 4 facsimile machine has been described, but the present invention can be similarly applied to other ISDN terminal devices.

[0073]

As described above, according to the present invention,
Since the transmission mode with the smaller communication cost is set between the circuit switching mode and the packet switching mode, efficient data transmission can be performed. Also. If the other terminal does not have the first selected transmission mode and the first call setup operation does not end normally, the call is re-established in the other transmission mode, ensuring reliable data transmission. You get the effect that you can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a group 4 facsimile apparatus according to an embodiment of the present invention.

FIG. 2 is a time chart showing an example of a transmission procedure in a circuit switching mode.

FIG. 3 is a time chart showing an example of a transmission procedure in a B channel packet switching mode.

FIG. 4 is a schematic diagram showing an example of a signal format of a call setting message.

5 is a flowchart showing an example of processing when the device of FIG. 1 makes a call.

[Explanation of symbols]

 1 control unit 2 system memory 11, 12 B channel transmission control unit

Claims (2)

[Claims] 1. An ISDN terminal device having an information channel transmission procedure function in a circuit switching mode and an information channel transmission procedure function in a packet switching mode, and first cost calculation means for calculating a transmission time in a circuit switching mode, A second cost calculating means for calculating the transmission time in the packet switching mode, and a transmission mode corresponding to the smaller one of the calculation results of the first cost calculating means and the second calculating means are selected. , An ISDN having control means for starting a call setting operation in the transmission mode.
Terminal device. 2. The control means, if the information channel is not established in the initially set transmission mode, recalls the destination in the other transmission mode. ISDN terminal equipment.