JPH01241959A - Communication system between multi-point - Google Patents

Abstract

PURPOSE:To obtain a multi-point conference system with simple constitution by applying different communication to incoming and outgoing direction of a communication channel, and transmitting one communication information to one direction of a loop communication channel and sending other communication information to other direction. CONSTITUTION:A terminal equipment 211 sends its own picture signal P1 to an outgoing line of a channel CH2 and the picture signal P1 is received via a terminal equipment 212 via a channel CH1 of the terminal equipment 212 and a digital network 22. The terminal equipment 212 receives the picture signal P1 to display the picture and sends it to an outgoing line of a channel CH2, then the picture signal P1 is received by a terminal equipment 213 via a digital network 22. The same operation as the terminal equipment 212 is applied to the terminal equipment 213 to display the received picture signal P1 and sent to a terminal equipment 214. The operation is applied sequentially by terminal equipments 212-21n to display the picture sent from the terminal equipment 211 on the terminal equipments 212-21n. Thus, with the transmission right of the picture given properly to each terminal equipment, the picture conference communication is applied among plural terminal equipments 211-21n.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a point-to-point communication system that performs communication such as image communication between multiple terminals at multiple points, such as a video conference telephone system.

The purpose of this invention is to put into practical use a multi-point conference system such as a video conference call between a large number of users with a simple configuration, without installing a large-scale and complicated conference telephone device on the digital network side.

Each of the plurality of terminals is connected to two other terminals via a digital network using different communication channels, thereby establishing a loop-shaped communication channel connecting the plurality of terminals. By performing different communications in each direction, the loop-shaped communication channel is configured such that one piece of communication information is transmitted in one direction and another piece of communication information is transmitted in the opposite direction.

[Industrial application field]

The present invention relates to an inter-point communication system, such as a video conference telephone system, in which communication such as image communication is performed between a plurality of terminals at multiple points.

[Conventional technology]

FIG. 4 shows an example of a conventional audio teleconference system as a system for simultaneous communication between terminals at multiple locations.

In this system, terminals 31 to 34 of each user participating in a telephone conference communicate with a communication bus 37. ~
374 and collect the audio signals v1 to v4 of each user to the -tan audio conference device 36, and in this audio conference device 36, the audio signals 2 and 4 of each user are added and distributed to each terminal 31 to 34. It sends synthesized voice signals of other users, thereby enabling simultaneous communication with multiple parties.

[Problem to be solved by the invention]

The above-mentioned audio conference telephone system has a problem in that as the number of users participating in the conference increases, the audio conference equipment installed within the communication network becomes complex and its scale rapidly increases. Also, when performing video conference communication using video communication as point-to-point communication.

Video signals, like audio signals, are burst signals (usually 1
Since there is only one speaker, there are silent periods in the audio signal from each user, and information is generated in bursts), but instead of a signal that needs to be displayed continuously (images of users participating in the conference). exist continuously), and cannot be simply added and synthesized like audio signals, so it is difficult to realize a video conference telephone system using the above-mentioned audio conference system. in this case,
Instead of simply adding and synthesizing video image signals, it is also possible to divide the screen according to the number of users participating in the conference and display each user's image on each divided screen, but l5D
When transmitting images and audio at a transmission speed of about 64khps, such as the N network.

In particular, it is necessary to perform significant bandwidth compression for images.
As a result, the image quality of the screen divided into many parts becomes extremely poor, so this method cannot be said to be practical.

Therefore, an object of the present invention is to avoid providing a large-scale and complicated conference telephone device on the digital network side.

An object of the present invention is to provide a point-to-point communication system that can realize a long point-to-point conference system such as a video conference phone between a large number of users with a simple configuration.

[Means to solve problems]

FIG. 1 is a block diagram of the principle according to the present invention.

In the point-to-point communication system according to the present invention, each of the plurality of terminals 211 to 21n is connected to the other two terminals via the digital network 22 using different communication channels C), CH2. multiple terminals 21.
A loop-shaped communication channel connecting between ~21□1 is set up,
By performing different communications in the up and down directions of the communication channels CI, C) 12, one communication information is transmitted in one direction through the loop communication channel, and another communication information in the opposite direction is transmitted. be done.

[Effect]

The point-to-point communication system according to the present invention is @terminal21. An example will be explained in which a terminal sends its own image signal P1 to other terminals 212 to 21n. 'Terminal 2h sends images B
The self-portrait signal P1 is sent to the F line of the channel CH2.

This image signal P is received by the terminal 212 via the digital network 22 and the uplink of the channel CH of the terminal 21. The terminal 212 receives this image signal P, displays it as an image, and sends it to channel CH2 as it is.
Send to the down line. As a result, this image signal P is then received by the terminal 213 via the digital network 22.

The terminal 213 performs the same operations as the terminal 21° to display the received image signal P1 as an image and send it to the terminal 214. When each of the terminals 212 to 21n sequentially performs this operation, the image transmitted from the terminal 211 is displayed on each of the terminals 21° to 2h. If image transmission rights are given to each terminal appropriately, multiple terminals 211
Image conference communication can be performed between 21□1.

[Example] The present invention will be described in detail below with reference to one drawing. FIG. 2 is a block diagram showing a video conference communication system using an inter-point communication method as an embodiment of the present invention. In the figure, 1 to 4 are user terminals, and each terminal 1 to 4 is equipped with an image communication function and an audio communication function. Each terminal 1 to 4 is connected to a basic 1sDN (integrated service digital network) line 1Jl15 via communication paths 11 to I4, and this l5
Each of the terminals 1 to 4 is interconnected via a DN network 5. Although the 15DN network 5 includes switching offices and the like, illustration of these switching offices and the like is omitted in FIG. 1 for the sake of clarity.

Two communication channels CH, CH2 of 64 kbps and one signal channel (not shown) of 16 kbps are set in the communication channels 11 to 14 by time division multiplexing.
Each of the terminals 1 to 4 is connected to the other two terminals via the l5DN line network 5 using these two communication channels CH, , CH2. A loop-shaped communication channel is configured.

A detailed configuration example of each terminal 1 to 4 is shown in FIG. In each terminal, when performing normal communication between two terminals, iN! The communication channel CH is used for image communication, and the communication channel CH2 is used for voice communication. Therefore, the communication channel CH is connected to the 64 kbps image codec 1 via the selector IL 12.
Connected to 0. Image codec 10 is decoder 1
In normal operation, the decoder 10 decodes the image signal Pr received from the uplink of the communication channel C1 and sends it to the image display device, and the encoder 102 decodes the image signal Pr received from the uplink of the communication channel C1 (, The image signal Ps from the camera is encoded and sent to the downlink of the communication channel CH.

Communication channel CH2 is connected to PCM audio codec 14 via selector 13. The audio codec 14 includes a decoder 14 and an encoder 142.

Normally, the decoder 141 decodes the audio signal Vr received via the uplink of the communication channel CH2 and sends it to the speaker, and the encoder 142 encodes the audio signal Vs from the microphone and sends it to the speaker. It is designed to be sent to the down line.

Selectors 11 to 13 are not normal one-to-one communications between two terminals.
This is a switch for switching between when performing conference call communication between multiple terminals and when performing conference call communication between multiple terminals.Input a side is selected in the case of communication between two terminals, and input side is selected in the case of conference call communication. is output. Therefore, in the case of conference telephone communication, the image signal Pr received via the up line of communication channel CH, is looped back to the down line G of communication channel CH2 via selector I1.13, and the audio signal of the own terminal is Vs is switched from being sent to the down line of the communication channel CH2 to being sent to the down line of the -ζ communication channel H via the selector 12.

Subtractor 16. Adder 18. Gates 5 and 17 and echo canceller 19 are circuits for performing conference telephone communication, and in the case of communication between two terminals, gates H5 and 17 are closed, and the audio signal S from the microphone is sent to adder 18. The decoded audio signal Vr from the decoder 141 is sent to the speaker via the subtractor 16. The echo canceller 19 is for canceling the audio signal (2) of the own terminal included in the received audio signal during conference telephone communication.

The operation of the embodiment described above will now be explained. When a conference call is made between terminals 1 to 4, each terminal is connected to two other terminals via the 15DN network 5, and a second terminal is connected between each terminal 1 to 4.
A loop-shaped communication channel as shown in the figure is set up.

At this time, the selectors 11-13 in each terminal 1-4 are switched to the input side. As a result, one image signal P is inputted to each terminal 1 to 4 via the uplink of the communication channel CH of each communication path 11 to 14, and is sent to other terminals via the downlink of the communication channel CH2. Therefore, the signal is transmitted counterclockwise through one line of the loop-shaped communication channel. - On the other hand, the voice signal is similarly transmitted clockwise over the opposite line of the looped communication channel.

First, image communication will be explained. In this system, only one terminal among terminals 1 to 4 participating in a conference can obtain the right to transmit images and transmit its own image signal to other terminals. There are various methods to obtain this transmission right.

For example, it is possible to determine which terminal is to be given the transmission right through negotiation between terminals through packet communication via a signal channel (D channel). In this negotiation, for example, a method such as giving the transmission right to the main speaker in the conference can be considered.

Assume that terminal 1 has now obtained the transmission right. Then, the terminal 1 switches the selector 11 to three input examples, thereby encoding the self-portrait signal P1 from the video camera in the encoder 102, and then transmitting it to the communication channel CH via the selector 11.13.
Send to the down line of 2. on the other hand.

In other terminals 2 to 4 that do not have transmission rights, the selectors 11 to 13 are switched to the input side, so the image signal P received via the uplink of 1 communication channel CH is decoded. The image is sent to the image display device via the converter 101 and displayed as an image, and is also sent as is to the downlink of the communication channel CH2 via the selector IL 13. Therefore, this image signal P] is sequentially sent counterclockwise from the terminal 1 through the loop communication channel to the terminals 2 to 4, and is displayed as an image at each terminal. In this way, by appropriately passing the image transmission right to each terminal, image communication between multiple terminals becomes possible.

Next, voice communication will be explained. Each terminal 1 to 4 converts its own audio signal Vs to an encoder 142. It is sent to the downlink of the communication channel CH through the selector 12, thereby sending out the looped communication channel clockwise sequentially to each terminal. At this time, the adder 18 of each terminal uses the communication channel CH
Since the audio signals of other terminals received via 2 are added to the audio signals of the own terminal, in the end, the audio signals sent from each terminal are the audio signals of all terminals participating in the conference.
.

-■ It becomes an addition composite signal of 4. Further, the synthesized voice signal (V, +V2 +V3→-V4) received by each terminal 1 to 4 via the uplink of the communication channel CH2 is decoded by the decoder 141, and then the voice signal of the terminal is decoded by the subtracter 16. , the audio signal output to the speaker is only a synthesized sound of audio signals from other terminals. By doing this, oscillations caused by the audio signal of the own terminal looping back through the loop-shaped communication path can be prevented.

Various modifications are possible in implementing the invention. For example, in the above-mentioned embodiment, moving image signals and audio signals are used as communication media information, but the communication is not limited to this, and communication of various media such as still image signals, facsimile image signals, or data communication signals can be handled. It is also possible. Furthermore, it goes without saying that the number of terminals is not limited to the four in the embodiment, and the configuration of the terminals is also not limited to that shown in the embodiment. Each terminal and l5DN
The communication path connecting the line networks is not limited to the time division multiplex communication path of the embodiment, but may also be, for example, a frequency division multiplex communication path or a space division communication path.

〔Effect of the invention〕

According to the present invention, a point-to-point communication system such as a video conference system can be realized with a simple configuration without setting up a large-scale special conference telephone device in a digital network. Furthermore, even if the number of users participating in the conference communication increases, no special measures need to be taken.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram according to the present invention. FIG. 2 is a block diagram showing a communication system using a multipoint borrowing method as an embodiment of the present invention. FIG. 3 is a block diagram showing an example of a detailed configuration of the terminal in FIG. 2. FIG. 4 is a block diagram showing a conventional conference telephone communication system. In fig. 1 to 4, 31 to 34 User terminals 11 to 14 - Communication path 5 - ISDN line network 10 - Image code filters 11 to 13 - Selector 14 - Audio code filters 15, 17 - Gate 16 - Subtractor 18 = - Addition Device 19 - Echo canceller Principle block diagram of the present invention

Claims (1)

[Claims] Each of the plurality of terminals (21_1 to 21_n) communicates with the other two terminals through different communication channels (CH_1, CH_n).
2) is used to connect the plurality of terminals (21_1 to 21_n) via the digital network (22), thereby establishing a loop-shaped communication channel connecting the plurality of terminals (21_1 to 21_n), and in the upstream direction of the communication channels (CH_1, CH_2). A multipoint communication system configured such that one piece of communication information is transmitted in one direction and another piece of communication information is transmitted in the opposite direction through the loop-shaped communication channel by performing different communications in the downstream direction.