JPH05276196A - Data transfer system - Google Patents

Abstract

PURPOSE:To provide the data transfer system eliminating the excess connection period of communication channels partially making a plurarity of call setting signals success calls, making an effective use of the communication channel and reducing the unrequired communication cost. CONSTITUTION:At the call setting, a call setting signal inserting user-user information requring two information channels is sent from television telephone set on the transmission. At the incoming television telephone set, when idle information channels as many as notified by the user-user information are present, a response signal is returned for the call setting signal. On the other hand, in the absence of idle information channels as many as notified by the user-user information, a release end signal is to be returned for the call setting signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for communicating between communication devices connected via an ISDN network by simultaneously using a plurality of communication channels.

[0002]

2. Description of the Related Art In recent years, ISDN (Integrated Services Digital Network) is being constructed to centrally manage information such as voice and data by a digital network in which a plurality of communication networks are integrated.

In the basic interface provided by this ISDN, two information (B1, B2) channels each having a bit rate of 64 kbps and one channel are provided on one communication line.
One signal (D) channel having a bit rate of 6 kbps is multiplexed and transmitted. Also, in the ISDN primary rate interface, 23 information channels each having a transmission rate of 64 kbps and the same 64 kbp are used.
One signal channel having a transmission rate of s is multiplexed and transmitted. The signal channel is a channel for commonly controlling a plurality of information channels transmitted by a basic interface or a primary rate interface, and for example, for transmitting a call control signal for controlling transmission / reception between a terminal and a network. Used. Further, one communication terminal can use a plurality of information channels at the same time, and thus, for example, a voice / data composite terminal in which voice and data are combined, or a videophone in which voice and image are combined, etc. Realization of a multimedia terminal becomes easy.

By the way, in the above-mentioned voice / data composite terminal, videophone, etc., it is necessary to set two information channels for transmission of voice and data, or voice and image, respectively, prior to the start of communication. Call setting is performed as follows, for example. FIG. 7 shows a circuit switching call control procedure by the D channel between the voice / data composite terminals which can use the two information channels B1 and B2. In the figure, the calling terminal first sends a call setting signal requesting the setting of the voice communication channel to the network, and then sends a call setting signal requesting the setting of the data communication channel. To do. A destination subscriber number for designating a communication partner is inserted in these call setting signals, and in the network, the B1 channel is designated for voice communication with respect to each of the two call setting signals coming from the calling side terminal. Also, a call setting signal that designates the B2 channel for data communication is sent to the terminal designated by the destination subscriber number.
When the called terminal responds to these call setting signals, the B1 and B2 channels are connected between the calling terminal and the called terminal, and thereafter voice communication using the B1 and B2 channels is performed. Data communication becomes possible.

Further, as shown in FIG. 8, a called terminal which has received two call setting signals from the network in response to a call setting request from the calling terminal has already used both B1 and B2 channels with a third party. In the case of performing voice and data communication by the caller terminal, the callee terminal sends back a release completion signal containing information indicating user busy to the two call setting signals, so that the caller terminal requests. Release each of the two call settings. In this case, the caller terminal will make a call again later.

Further, as shown in FIG. 9, when the receiving side terminal which has received two call setting signals from the network is already performing voice communication with a third party, for example, using only the B1 channel. This called terminal sends a response signal to one of the above two call setting signals,
A release completion signal including information indicating user busy is sent to the other call setting signal. As a result, for example, although the call setup for data communication is accepted and data communication becomes possible, the call setup for voice communication becomes an incomplete call and the call cannot be performed. In this case, the originating terminal disconnects the data communication channel that has been successfully connected, and re-transmits until the necessary information channel is secured.

[0007]

As described above, the terminal requesting call setup to the terminal already communicating with the third party is
When only a part of the required information channel can be secured, the terminal which has made the call setting request once gives up the communication and tries again afterwards. However, there is a problem in that the communication charge is added each time the information channel once connected is disconnected, and the utilization efficiency of the information channel is reduced due to the disconnection.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission system which eliminates a meaningless connection period of a communication channel to effectively utilize the communication channel and can reduce unnecessary communication cost.

[0009]

To achieve the above object, the present invention provides a data transmission system for performing data transmission between communication devices connected via an ISDN network using a plurality of communication channels simultaneously. The originating communication device has a user interface that indicates the number of communication channels required at call setup.
The number of units notified by the user / user information when the call setting signal including the user / user information has arrived at the communication device on the receiving side, while having means for transmitting the call / setting signal in which the user information is inserted. And a call setting control means for determining whether or not there is an available communication channel. When there is the number of available communication channels notified by the user / user information as a result of the determination by the determination means, the call setting control means responds to the call setting signal, while When there is no available communication channel of the number notified by the user / user information as a result of the determination, the call setting control means releases the call setting signal.

[0010]

As a result, according to the present invention, even if the communication device on the receiving side has an empty communication channel, the number of empty information channels is secured by the number notified by the user / user information in the call setting signal. Only in this case, a response is made to the call setup signal and the subsequent call setup signal, and the communication channel is set up. If the number of free communication channels in the communication device on the receiving side is less than the number notified by the user / user information, the call setting signal is released and the communication channel is not set. As a result, it is possible to prevent a problem that a plurality of call setting requests sent from the communication device on the calling side partially become successful calls and a useless connection period of the communication channel occurs.

[0011]

EXAMPLE An example of the present invention will be described below. In this embodiment, the ISDN basic interface (2B + D)
A case will be described as an example where voice and image communication is performed between videophones using the.

FIG. 1 is a block diagram showing the configuration of a video telephone used in a data transmission system according to an embodiment of the present invention. In the figure, this video telephone has a microprocessor unit (MPU) 1 and a ROM 2
, RAM3, handset 4, voice codec 5
, A television camera 6, a display 7, an image codec 8, an ISDN network interface (ISDNI /
F) 9, an operation unit 10, and a speaker 11. The voice codec 5 PCM-encodes the analog call signal input from the handset 4 into a digital call signal of 64 kbps and transmits it, and decodes the digital call signal of 64 kbps coming from the partner terminal to restore the original analog call signal. After reproduction, this analog call signal is supplied to the handset 4 to output a voice. Further, the image codec 8 band-compresses the image signal input from the television camera 6 into a digital image signal of 64 kbps, performs inter-frame coding and transmits, and decodes the digital image signal of 64 kbps coming from the other party's terminal. After reproducing the original image signal, the image signal is supplied to the display 7 to output an image.

The ISDN network interface 9 functions as an interface with an ISDN network (not shown), and has two information (B1, B2) channels and one signal (D) channel according to the channel structure of the basic interface. And multiplex and separate. The ISDN network interface 9 and the voice codec 5 are connected via a B1 channel, and the ISDN network interface 9 and the image codec 8 are connected via a B2 channel.

The MPU 1 controls the entire videophone during data transmission according to a control program stored in the ROM 2 in advance, and the call setting information notifying means 1
a and call setting control means 1b. The call setting information notifying means 1a is user / user information indicating the number of information channels required in the call setting signal of the first one of the two call setting signals generated at the time of transmission, that is, "2".
The number of information channels required for communication is notified to the terminating side terminal by inserting user / user information indicating the. Further, the call setting control means 1b supplies the user / user information to the RAM 3 for temporary storage when the call setting signal including the user / user information arrives from the ISDN network. The presence / absence of the notified number of free information channels, that is, the presence / absence of two free information channels is determined. If both of the information channels are free as a result of this determination, a response signal to the call setting signal is generated and sent to the ISDN network. On the other hand, if at least one information channel is occupied by communication with another terminal, a release completion signal for releasing the call setting signal is generated and sent to the ISDN network. Next, the operation of the data transmission system configured as described above will be described.

FIG. 2 shows B in the video telephone of the receiving side.
6 shows a call control procedure when both the 1 and B2 channels are idle. In the figure, the calling party makes a call by dialing the subscriber number of the communication partner from the operation unit 10 of the videophone. Then, a call setting signal for setting a voice communication channel is first sent from the video telephone to the network. Here, in general, the ISDN user
According to the layer 3 protocol of the network interface, for example, as shown in FIG. 5, a protocol identifier 51, a message type 52, a transmission capability information element 53, a channel identifier information element 54, a called number information element 55 and user / user information 56. A call control message composed of each call control information is inserted.

The protocol identifier 51 indicates whether the information transmitted in this message is for the D channel signal or X. Two
5 is for packet calls. The message type 52 is for identifying various messages such as call origination / response / disconnection / release completion for call control. The transfer capability information element 53 is for designating the exchange format (line / packet) and the information transfer capability (voice / digital, etc.). The channel identifier information element 54 specifies the information channel used on the interface.
The called party number information element 55 is for designating a destination. The user-user information 56 is information that is transparently transferred between data terminals without being checked by the network, and is used for transmitting relatively short information between users. In the case of the call setting signal, (a) of FIG.
, The protocol identifier 51 is for the D channel signal, the message type 52 is the call setting, and the transfer capability information element 5
A call setup message is inserted in which the switching format of No. 3 is circuit switching, the information transfer capability is voice, and the channel identifier information element 54 designates an arbitrary B channel on the basic interface. Also, the subscriber number of the receiving side video telephone is inserted in the called number information element 55, and the number of information channels required by the calling side video telephone, that is, the user / user information indicating "2" is included in the user / user information 56. Is inserted.

Now, in the network which has received the call setting signal including the above call setting message from the calling side video telephone, the line of the video telephone designated as the incoming call based on the called number information element 55 included in this call setting signal. After selecting, the call setting signal for designating the B1 channel for voice communication is sent to the video telephone. The videophone on the called side analyzes the user / user information in the call setting signal coming from the network, and based on the communication status of the own device at this point, the number of empty information channels notified by the user / user information. , Ie, the presence or absence of two free information channels. As a result, B1 and B2
When it is determined that both channels are in the idle state and there are two available information channels requested by the videophone on the calling side, the videophone on the called side generates a response signal to the call setting signal and sends it to the network. Send out. The response message included in this response signal is, for example, as shown in FIG. 6B, each call in which the protocol identifier 51 is for the D channel signal, the message type 52 is the response, and the channel identifier information element 54 is the B1 channel selection. It is composed of control information. Also, the videophone on the receiving side that has sent this response signal regulates call setting requests from other videophones after the same time. Such incoming control is performed by storing a caller ID number (not shown) included in the call setting message in the RAM 3 and comparing it with a caller ID number in a call setting signal that arrives thereafter. .. That is, the source I stored in the RAM 3
When the D number and the sender ID number in the call setting signal coming from the network do not match, the release completion signal is sent to reject the incoming call from the third party. The network that has received the response signal is channel identifier information element 5
A response signal in which 4 is designated as the B1 channel is sent to the videophone on the calling side.

On the other hand, the videophone on the calling side sends the call setting signal for setting the voice communication channel, and thereafter does not send the call setting signal for setting the image communication channel, and the above-mentioned voice communication. It is in a waiting state for a reply to a call setting signal for setting a communication channel. When a response signal from the network is received, it is determined that the videophone on the receiving side has two available information channels, and a call setting signal for setting the image communication channel is sent to the network. The network that received this call setup signal
A call setting signal that designates the B2 channel for image communication is sent to the receiving side video telephone. At this time, the videophone on the receiving side surely secures the B2 channel due to the above-mentioned incoming call regulation, and when the call setting signal for setting the above-mentioned image communication channel is received, it is confirmed that the sender ID numbers match. Then return the response signal. That is, in the videophone on the calling side, when a response signal is received in response to a call setting signal for setting a channel for voice communication, a call setting signal for setting a channel for image communication to be sent subsequently is set. Also, the response signal can be received without fail. When a response is made to each of the two call setting signals in this way, communication of an audio signal by the B1 channel and an image signal by the B2 channel becomes possible thereafter, and the communication as a videophone is started. Next, a call setting procedure when only the B1 channel is already used for voice communication in the videophone on the receiving side will be described with reference to FIG.

In the figure, when the caller on the caller side dials in the subscriber number of the callee, a call set-up signal for setting a voice communication channel is sent from the videophone on the caller side to the network. .. The call setting signal shown in FIG.
The call setup message shown in (a) is inserted,
The network sends a call setup signal with the channel identifier information element 54 designated as the B2 channel toward the videophone designated by the called number information element 55. The videophone on the receiving side determines the presence / absence of two idle information channels based on the user / user information in the incoming call setting signal. As a result, when only the B2 channel is in an empty state, and when it is determined that there are no two empty information channels requested by the videophone on the calling side, the videophone on the called side releases the user busy signal to the call setting signal. A completion signal is generated and sent to the network, and the network sends a release completion signal to the originating videophone. On the other hand, when the videophone on the calling side, which is waiting for a reply to the call setting signal for setting the channel for voice communication, receives the release completion signal from the network, the videophone on the called side receives two empty information channels. If it is determined that there is no such a call, the call setting signal for setting the image communication channel is not sent, and the call is released.

As described above, according to the present embodiment, when the number of available information channels in the videophone on the receiving side is less than the number notified as user / user information from the videophone on the calling side, that is, "2". , The called videophone does not send back a response, but instead sends a release complete signal. Therefore, it is possible to prevent the problem that a wasteful information channel is set between the videophone on the calling side and the videophone on the receiving side, which can reduce unnecessary communication cost and make effective use of the information channel. Is possible.

The present invention is not limited to the above embodiment. For example, in the above embodiment, when the number of information channels notified as user / user information from the calling side video phone at the time of call setting in the called side video phone cannot be secured, the call setting is rejected. As shown in FIG. 4, the call setting signal for voice communication is first accepted as the call setting accepting state or the calling state, and the response is delayed until the number of information channels notified by the user / user information is secured. , When a required information channel is secured, a response signal is sent out, a voice communication channel is connected, and then the arrival of a call setup signal for image communication is awaited, while other call setup requests are regulated. Good. In this way, even if the incoming call side signal is rejected due to the user's busyness or the like in the videophone on the receiving side, it is possible to prevent the need for re-calling and to prevent unnecessary monopolization of the signal channel.

Further, in the above-mentioned embodiment, the description has been made by taking the video telephone as an example of the communication terminal. However, a plurality of such terminals can be used for simultaneous communication of different information media such as a voice / data composite terminal for transmitting voice and data. The present invention can be applied to all communication terminals that sequentially set call settings. Further, in the above embodiment, the communication terminal using the ISDN basic interface has been described, but it is also possible to apply this to a communication terminal using an interface in which a larger number of communication channels are multiplexed, such as a primary rate interface. Is. In addition, various modifications can be made without departing from the scope of the present invention.

[0023]

As long as the number of idle information channels in the communication device on the receiving side is secured by the number notified by the user / user information in the call setup signal, the call setup signal is answered and the incoming call is received. When the number of idle communication channels in the communication device on the side is less than the number notified by the user / user information, the call setting signal is released. Data that can prevent unnecessary connection period of communication channel due to partial success of call setup request, thereby enabling effective use of communication channel and reducing unnecessary communication cost A transmission system can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video phone used in a data transmission system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a communication sequence of a D channel call control procedure according to an embodiment of the present invention.

FIG. 3 is a diagram showing a communication sequence of a D channel call control procedure according to an embodiment of the present invention.

FIG. 4 is a diagram showing a communication sequence of a D channel call control procedure according to an embodiment of the present invention.

FIG. 5 is a diagram showing a call control message inserted in a call control signal.

FIG. 6 is a diagram showing a call setup message and a response message.

FIG. 7 is a diagram showing a communication sequence of a D channel call control procedure according to a conventional example.

FIG. 8 is a diagram showing a communication sequence of a D channel call control procedure according to a conventional example.

FIG. 9 is a diagram showing a communication sequence of a D channel call control procedure according to a conventional example.

[Explanation of symbols]

1 ... Microprocessor unit (MPU), 2 ... RO
M, 3 ... RAM, 4 ... Handset, 5 ... Audio codec, 6 ... Television camera, 7 ... Display, 8 ... Image codec, 9 ... ISDN network interface (ISDNI)
/ F), 10 ... Operation unit, 11 ... Speaker.

Claims (2)

[Claims] 1. A data transmission system for performing data transmission between communication devices connected via an ISDN network by simultaneously using a plurality of communication channels, wherein the communication device on the originating side has a communication channel required at the time of call setup. The communication device on the receiving side is provided with means for transmitting a call setting signal in which user / user information indicating the number is inserted, and when the call setting signal including the user / user information arrives, Judgment means for judging the presence or absence of the notified free communication channels, and the call setting signal when it is judged by this judgment means that there are the free communication channels notified by the user / user information. To the user
A data transmission system, comprising: a call setting control means for releasing the call setting signal when it is determined that the number of available communication channels notified by the user information does not exist. 2. A data transmission system for performing data transmission between communication devices connected via an ISDN network by simultaneously using a plurality of communication channels, wherein the communication device on the originating side has a communication channel required at the time of call setup. The communication device on the receiving side is provided with means for transmitting a call setting signal in which user / user information indicating the number is inserted, and when the call setting signal including the user / user information arrives, Judgment means for judging the presence or absence of the notified free communication channels, and the call setting signal when it is judged by this judgment means that there are the free communication channels notified by the user / user information. To the user
If it is determined that the number of available communication channels notified by the user information does not exist, a call that delays the response to the call setting signal until the number of available communication channels notified by the user / user information is secured. A data transmission system comprising: setting control means.