JP2000244491A - Multi-point conference system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a required transmission channel frequency band from being increased in proportion to the number of participants and to avoid a propagation delay of information and changes in speakers from being increased even when the number of the participants is increased. SOLUTION: An edge device 2 aborts packets from terminals 1 other than a terminal of a speaker based on a speaker notice received from a center device 13. The edge device uses a multi-cast transmission means 21 to transmit information of a speaker terminal t other edge device and a transmitted packet is copied by a multi-cast function of a packet exchange network and delivered to a plurality of edge device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for an apparatus for realizing a conference by three or more users on a communication network.

[0002]

2. Description of the Related Art (Regarding a Multipoint Conference System) A communication system for holding a conference between people at three or more remote locations is called a multipoint conference system. FIG. 13 is a conceptual diagram of the multipoint conference system. As shown in FIG. 13, a function required for the multipoint conference system is a function for transmitting and receiving information between three or more terminal devices on the assumption that any terminal device can be a speaker terminal device. . Further, it is desired that more conferences can be realized with better quality by effectively utilizing the transmission path bandwidth of the network. (Regarding the multicast function of the packet switching device) As a method of realizing the multipoint conference system, a method using a multicast function of a packet switching network such as an IP network is considered. First, the multicast function of the IP network will be described.

An IP network is a network generally used as a communication means between computers, and a packet switching device called an IP router transfers packets.
In the IP network, each terminal device is assigned an address called an IP address.

In order to enable a certain terminal device to communicate with a plurality of terminal devices simultaneously, a logical address is formed by adding a value called a port number to an address.
FIG. 14 is a conceptual diagram of packet communication using an IP network.
FIG. 14 shows that the terminal device TE1 and the terminal device TE4 are communicating, but the terminal device TE1 has an IP address of t1 and uses a port number of a for communication with the terminal device TE4. It has an IP address of t4 and uses a port number of b for communication with the terminal device TE1.

The terminal writes the logical address used by the terminal itself as the source address, writes the logical address used by the terminal of the communication partner as the destination address, and sends the packet to the IP router. The IP router identifies the destination address written in the packet and forwards the packet to an appropriate output port. As shown in FIG. 14, a wide area IP network is constructed by connecting a plurality of IP routers.

Further, many IP routers have a function of copying a packet and transferring the same packet to a plurality of destinations. This is called multicast. FIG. 15 is a conceptual diagram of the multicast transfer by the IP router. In this case, a multicast address is used as the destination address of the packet as shown in FIG.
A multicast address and a list of a plurality of packet transfer destinations corresponding to the multicast address are registered in the multicast group table of the router.

[0007] Upon receiving a packet whose destination address is a multicast address, the IP router transfers the packet to a packet transfer destination corresponding to the multicast address. Meanwhile, packet transfer from one terminal device to one terminal device is called unicast.

[0008] When a plurality of connected IP routers perform multicasting, it is possible to perform multicasting for a plurality of terminal devices connected to a wide area IP network. FIG.
Is a multicast function of IP network (mesh connection is realized)
FIG. As shown in FIG. 16, multicasting over an IP network is characterized in that any terminal device in the multicast group can become a transmitting terminal device. Such communication means between the terminal devices will be referred to as a mesh connection channel.

[0009] In the multicast communication over the IP network, there is a characteristic that any terminal device existing in the delivery range of a packet can participate in the multicast communication. (Multipoint Conference System Using Multicast Function of Packet Switching Network) A packet switching device having a multicast function can realize the above-mentioned multipoint conference system. In other words, when using an IP router as a packet switching device,
One mesh connection channel may be set for the conference group. The characteristics of the communication band required in this system will be described below.

[0010] For example, when a TV conference is held between M participants in the Kanto region and N participants in the Kansai region, video information always flows from the terminal device of the non-speaking participant. M video streams, N from Kansai to Kanto
The video stream of the book will flow. FIG. 17 is a conceptual diagram of a multipoint conference using a mesh connection channel.
FIG. 17 shows the case where M = 3 and N = 3. Focusing on a transmission path (relay path) connecting between two remote areas, there is a characteristic that the transmission path bandwidth to be secured on the path increases in proportion to the number of participants. Also,
Since information from all the participant terminal devices other than the terminal device is transferred to each terminal device, the required bandwidth of the terminal device connection line increases in proportion to the number of participants. (About Multipoint Conference Unit (MCU)) FIG.
FIG. 2 is a conceptual diagram of a multipoint communication using an MCU and an MCU.
FIG. 19 is a conceptual diagram of multipoint conference communication using an MCU. As another method for realizing a multipoint conference system, there is a method using a device called a multipoint conference connection device (MCU). As shown in FIG. 18, the MCU receives information from each participant terminal device, recognizes a terminal device in the conference group as a speaker, and receives the information from the speaker terminal device while responding to the switching of the speaker. A function of broadcasting the information to each participant terminal device. As a recommendation that defines the technical specifications of a data conference using an MCU, ITU-TT. 12
0 as a recommendation that defines the technical specifications of audio / video conferencing using the MCU. 231.

As one method of recognizing a speaker, there is a method of transmitting a control message designating the speaker from the terminal device serving as the chair to the MCU. Another method is for the MCU to automatically select the speaker. In this case, the MCU
Obtains some comparison information for each terminal device based on the information received from each terminal device, and compares the comparison information among the participants to determine the speaker. As a typical method of obtaining comparison information in a TV conference or the like, there is a method of calculating the volume of each participant.

Another method for obtaining comparison information is as follows.
In some cases, when a conference participant wants to speak, control information including a priority and a waiting time until the speech is sent to the MCU. In this case, the MCU performs a comparison operation between the participants using the comparison of the requested arrival time, the comparison of the priority, and the like. One MCU
In the case where multi-point communication is realized by using, the characteristics of the required communication band are described below.

In the above-described example in which the M participants in the Kanto region and the N participants in the Kansai region hold a TV conference, it is assumed that an MCU is installed in the Kanto region as shown in FIG. By using the MCU, the information received by each terminal device is only information from the speaker, so that the required bandwidth of the terminal device connection line is the information transmission rate per terminal device. But,
Information on N terminal devices in Kansai always flows on the Kanto-Kansai transmission line. Therefore, the characteristic that the bandwidth of the transmission path to be secured on the path connecting the two remote areas increases in proportion to the number of participants is not significantly improved.

As a method of reducing the required bandwidth on a transmission path between regions, there is a method of connecting MCUs in multiple stages. FIG.
It is a conceptual diagram of the multistage connection of CU. This is to connect one MCU as another terminal device to another MCU as shown in FIG. In this case, the MCU of the lower tier selects one of the terminal devices connected to itself as the speaker terminal device, and inputs only the information from the speaker terminal device to the upper tier, and from the upper tier, The received information is distributed to the terminal device connected thereto.

In the case where multi-point communication is realized by connecting the MCUs in multiple stages, the characteristics of the necessary communication band will be described below. FIG. 21 is a diagram illustrating multipoint communication using an MCU (an example in which MCUs are connected in multiple stages). As shown in FIG. 21, it is assumed that MCUs are installed in the Kanto region and the Kansai region in an example in which the M participants in the Kanto region and the N participants in the Kansai region have a TV conference. In this case, the bandwidth to be secured on the transmission line between the Kanto and Kansai regions is also the information transmission rate per terminal device.

Most of the MCUs are realized by mounting dedicated software on a general-purpose computer. The MCU performs a process of copying data for the number of connected terminal devices, but since the load of this process is large,
Many Ms realized using general-purpose computers
One CU cannot accommodate many terminal devices. Therefore, even when a conference is held between remote participants, if the number of participants exceeds the number that can be accommodated by one MCU, the MCUs are connected in multiple stages and the processing load is reduced to a plurality of MCUs. Disperse and realize meetings.

However, if the MCUs are connected in multiple stages, the time required for switching the speakers increases in proportion to the number of stages, so that the quality of provision is degraded. For example, when the speaker is automatically identified based on the volume of the participant, the time required for switching the speaker is a value obtained by multiplying the time required to calculate the volume in each stage by the number of connection stages. In addition, since information passes through a plurality of MCUs while being transmitted from the speaker to another participant, the information propagation delay increases in proportion to the number of stages by the delay caused by the information transfer processing in the MCU. .

[0018]

The problem that the required bandwidth increases in proportion to the number of participants, which is a problem of the multipoint conference system using the multicast function of the packet switching network, is solved by the multipoint conference using the MCU. You. However, the multipoint conference using the MCU has the following problems.

The problem of increasing the number of MCU multi-stage connections: one M
Since the number of participants that can be accommodated by a CU is limited, it is necessary to connect MCUs in multiple stages to accommodate many participants. FIG. 22 is a diagram showing the relationship between the number of participants and the number of multistage connections. For example, as shown in FIG.
If the number of participants can be accommodated, it is necessary to connect the MCUs in three stages to realize a conference in which 200 people participate. Also, even if a meeting is held with 100 people, if 100 people are in the same area, the number of MCU connection stages is only two, but 50 people are in Tokyo and 50 people are in Osaka. , The number of MCU connection stages is three. When the number of connection stages increases, problems such as an increase in the time required for switching speakers and an increase in information propagation delay become serious obstacles.

The present invention has been made in such a background, and the required transmission path bandwidth does not increase in proportion to the number of participants, and even if the number of participants increases, the information can be transmitted. An object of the present invention is to provide a multipoint conference apparatus in which propagation delay and switching of speakers do not increase.

[0021]

SUMMARY OF THE INVENTION A multipoint conference apparatus according to the present invention comprises an edge device and a center device, and the center device identifies a speaker terminal among terminal devices participating in a conference. Identification means, and means for transmitting a speaker notification message notifying the identified speaker to the edge device, wherein the edge device receives a packet from the terminal device, and discards or addresses the received packet. The edge device comprises: a filter unit for rewriting; a multicast packet transmitting unit for transmitting the packet with the destination of the packet not discarded after the filtering process as a multicast address; and a unit for receiving a speaker notification message from the center device. Updates the filter settings according to the content of the speaker notification message and is discarded Change the came packet, characterized in that it transferred to other devices using a multicast packet transmitting unit packets received from the speaker terminal. The receiving device of the multicast packet includes an implementation that is an edge device and an implementation that is a terminal device.

Compared with the conventional system in which the MCUs are connected in multiple stages, the feature is that information is copied by the multicast function of the packet switching network, which is performed by the conventional higher-level MCU. Note that the MCU of the lowest order in the conventional method corresponds to the edge device, but the MCU of the lowest order is
For the copying of the information that has been performed, there can be a method realized by the edge device and a method performed by the multicast function.

The center device corresponds to the upper-level MCU in the conventional system, but the center device corresponds to the upper-level MCU.
Instead of transmitting information to the edge device, and updating the filter so that the edge device does not transmit packets from terminal devices other than the speaker based on the information. The points are different.

Further, when the multipoint conference apparatus autonomously recognizes the speaker without using the speaker instruction message from the terminal device, the edge device identifies the speaker from the packet received from the terminal device. Means for obtaining a comparison value as information for transmitting a comparison value notification message indicating the obtained comparison value to the center device, wherein the center device receives a comparison value notification message from the edge device; Wherein the center device identifies the speaker based on the comparison value indicated in the comparison value notification message. It differs from the conventional method in which the upper-level MCU calculates the comparison value from the information received from the lower-level MCU to identify the speaker, in that the center device identifies the speaker using the comparison value received from the edge device.

FIG. 23 is a diagram showing a comparison between the conventional system and the present invention. That is, as shown in FIG. 23, the edge device discards a packet from a terminal device other than the speaker based on the speaker notification received from the center device, so that the conventional filter means of the higher-level MCU is unnecessary. Further, the edge device transmits information of the speaker terminal device to another edge device using the multicast transmission means, and the transmitted packet is copied by the multicast function of the packet switching network and distributed to a plurality of edge devices.

In other words, the broadcast of the copy of the speaker information to the lower-level MCU, which has been performed by the conventional higher-level MCU, is performed by the multicast function of the packet switching network. Since the data is copied and broadcast using the multicast function of the packet switching network, the information is transmitted from the edge device accommodating the speaker terminal device to another edge device by direct packet communication between the edge devices without passing through the upper tier device. Is done. As a result, the portion of the information propagation delay between the terminal devices that has been generated by the transfer processing in the upper-level ladder device disappears, and the effect that the information propagation delay does not need to be large even if the number of participants increases. . Further, if the edge device is provided with the copy broadcasting means, it is not necessary to provide the terminal device with the multicast packet receiving means.

In FIG. 23, the multicast packet receiving device is another edge device. However, as another embodiment of the present invention, a terminal device may be a multicast packet receiving device.

Further, when the speaker is autonomously identified without using the speaker control message from the terminal device, the center device receives the comparison value obtained by the edge device from the edge device, and based on the received comparison value. Identify the speaker. Thus, the speaker can be identified without the center device performing the process of acquiring the comparison value. As a result, the time required for switching speakers can be reduced.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a main part of a multipoint conference apparatus according to the present invention. FIG. 2 is a block diagram of a main part of the multipoint conference apparatus according to the first embodiment of the present invention.

According to the present invention, as shown in FIG. 1, an edge device 2 to which a plurality of terminal devices 1 are connected,
Is a multipoint conference device provided with a center device 3 to which is connected.

Here, the feature of the present invention is that the center device 3 is a speaker identification means 30 for identifying the speaker terminal device 1 among the plurality of terminal devices 1 participating in the conference.
And a speaker notification transmitting unit 31 that transmits a speaker notification message notifying the terminal device 1 of the speaker identified by the speaker identifying unit 30 to the edge device 2. Filter means 20 for receiving a packet, discarding the packet and rewriting the address of the received packet, and a multicast packet for transmitting the packet with the destination of the packet not discarded after filtering by the filter means 20 as a multicast address Transmission means 21 and center device 3
And a speaker notification receiving unit 22 for receiving a speaker notification message from the communication device. The filtering unit 20 discards a packet from the terminal device 1 other than the speaker according to the content of the speaker notification message, and Reference numeral 21 indicates that the packet received from the terminal device 1 of the speaker is transferred to another device by the multicast packet transmitting means 21 in accordance with the content of the speaker notification message.

In the embodiment of the present invention, as shown in FIG. 2, the edge device 2 includes a comparison value acquisition unit 23 for acquiring a comparison value as information for identifying a speaker from a packet received from the terminal device 1. And a comparison value notification transmitting unit 24 for transmitting a comparison value notification message indicating the obtained comparison value to the center device 3. The center device 3 receives the comparison value notification message from the edge device 2.
And the speaker identification means 30 identifies the speaker based on the comparison value indicated in the comparison value notification message.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a diagram showing a protocol stack of the conference terminal device. FIG. 4 is a flowchart showing the operation of the terminal device. FIG. 5 is a diagram illustrating an example of the comparison value table of the edge device. FIG. 6 is a flowchart showing the operation of the edge device. 7 and 8 are diagrams showing examples of the comparison value notification message. FIG. 9 is a diagram illustrating an example of the comparison value table of the center device. FIG. 10 is a flowchart showing the operation of the center device.

The terminal device 1, edge device 2, and center device 3 shown in FIG. 2 are each mounted on a general-purpose PC. The terminal device has means for transmitting and receiving audio and video according to the protocol stack shown in FIG. 3 and means for transmitting and receiving data.
As shown in the flowchart of FIG. 4, information is continuously transmitted and received from the start of the conference to the end of the conference. That is, the destination IP address of information transmission, the port number, the IP address to be received,
A conference is started on the precondition that a port number is set, and information is transmitted and received. The conference ends when the conference time expires or when the user selects the end button.

The edge device is provided with a table for storing user comparison values as shown in FIG.
It operates according to the flowchart shown in FIG. That is,
When the packet arrives from the user, the comparison value is updated, the packet is determined to be passed or discarded according to the setting of the filter means 20, and if the packet is a passed packet, the destination is rewritten to the group address for the conference and the packet is transmitted to the mesh connection channel 40. It forwards and discards the packet if it is a discarded packet. In addition, a comparison value notification message is repeatedly sent to the center device 3 with T1 as a cycle.

When the speaker notification message arrives from the center device 3, the setting of the filter means 20 is updated.
Only packets from the user specified as the speaker are passed packets. The forms of the comparison value notification message and the speaker notification message are as shown in FIGS. 7 and 8, and these messages are transmitted. UDP / IP or TCP / IP may be used as the lower layer protocol.

The center device has a table for storing user comparison values as shown in FIG. 9 and operates according to the flowchart of FIG. That is, when the comparison value notification message arrives from the edge device 2, the comparison value table of the comparison value notification receiving means 32 is updated based on the message. Also, T2
Is transmitted as a cycle to the edge device 2 involved in the conference. At this time, the speaker is updated by referring to the comparison value table and selecting the user having the largest comparison value as the speaker.

Instead of the edge device 2 acquiring the comparison value and notifying the center device 3 of the comparison value, the center device 3 receives the speaker instruction message from the terminal device 1 and identifies the speaker. There can be.

In the first embodiment of the present invention, the multicast packet from the mesh connection channel 40 is directly transferred to the terminal device 1. Therefore, the terminal device 1 includes a multicast packet receiving unit. The illustration of the multicast packet receiving means in the terminal device 1 is omitted.

(Second Embodiment) FIG. 11 shows a second embodiment of the present invention.
This will be described with reference to FIG. FIG. 11 is a block diagram of a main part of a multipoint conference apparatus according to a second embodiment of the present invention.
FIG. 12 is a flowchart showing the operation of the copy broadcasting means.

As shown in FIG. 12, the edge device 2 includes the multicast packet receiving means 26 and the copy broadcasting means 25, and the multicast packet received from the mesh connection channel 40 is transmitted to the terminal device 1 in which the edge device 2 accommodates. On the other hand, this embodiment differs from the first embodiment of the present invention in that copy broadcast transmission is performed. The copy broadcasting means 25 operates according to the flowchart of FIG. That is, the conference is started on the precondition that the IP address and the receiving port number of the accommodated terminal device are registered, and when a multicast packet is received from the mesh connection channel 40, all the terminals accommodated in the edge device 2 are received. A multicast packet is copied to the device 1 and transmitted by multicast. The conference ends when the conference time expires.

The second embodiment of the present invention has an advantage that the terminal device 1 does not need to have the multicast packet receiving means.

[0043]

As described above, according to the present invention,
A multi-person conference can be realized by mutual communication between locations where a plurality of conference devices are distributed without the need to connect MCUs in multiple stages.
As a result, there is an effect that it is possible to realize a multipoint conference in which the required transmission path bandwidth does not increase in proportion to the number of participants and the switching of speakers does not increase even if the number of participants increases. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a multipoint conference device according to the present invention.

FIG. 2 is a block diagram of a main part of the multipoint conference apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a protocol stack of the conference terminal device.

FIG. 4 is a flowchart showing the operation of the terminal device.

FIG. 5 is a diagram showing an example of a comparison value table of the edge device.

FIG. 6 is a flowchart showing the operation of the edge device.

FIG. 7 is a diagram showing an example of a comparison value notification message.

FIG. 8 is a diagram showing an example of a comparison value notification message.

FIG. 9 is a diagram showing an example of a comparison value table of the center device.

FIG. 10 is a flowchart showing the operation of the center device.

FIG. 11 is a block diagram of a main part of a multipoint conference apparatus according to a second embodiment of the present invention.

FIG. 12 is a flowchart showing the operation of the copy broadcasting means.

FIG. 13 is a conceptual diagram of a multipoint conference system.

FIG. 14 is a conceptual diagram of packet communication using an IP network.

FIG. 15 is a conceptual diagram of multicast transfer by an IP router.

FIG. 16 is a conceptual diagram of a multicast function (realizing a mesh connection) of the IP network.

FIG. 17 is a conceptual diagram of a multipoint conference using a mesh connection channel.

FIG. 18 is a conceptual diagram of a mechanism of an MCU and multipoint communication using the MCU.

FIG. 19 is a conceptual diagram of multipoint conference communication using an MCU.

FIG. 20 is a conceptual diagram of multi-stage connection of MCUs.

FIG. 21 is a diagram showing multipoint communication (an example in which MCUs are connected in multiple stages) using an MCU.

FIG. 22 is a diagram showing a relationship between the number of participants and the number of multistage connections.

FIG. 23 is a diagram showing a comparison between a conventional method and the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal device 2 Edge device 3 Center device 20 Filter means 21 Multicast packet transmission means 22 Speaker notification reception means 23 Comparison value acquisition means 24 Comparison value notification transmission means 25 Copy broadcast means 26 Multicast packet reception means 30 Speaker identification means 31 Speaker notification transmitting means 32 Comparison value notification receiving means 40 Mesh connection channel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/15 610 (72) Inventor Shunsuke Yoshida 3-2-1-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone In-house F term (reference) 5C064 AA02 AC09 AC11 AD16 5K015 AA01 AB00 AB01 AF01 JA00 JA01 JA10 JA12 5K030 GA18 HA08 HB16 HD09 JA07 KA04 LA19 LC00 LC18 LD02 LD08 5K033 BA14 CB06 CB09 CB13 DA15 DB12 DB16 DB18 CB10 CC03 CC02 HZ15 HZ23 JJ18 JJ19 JJ23 JJ25 KK56

Claims (4)

[Claims] 1. A multipoint conference apparatus comprising: an edge device to which a plurality of terminal devices are connected; and a center device to which the edge device is connected, wherein the center device includes a plurality of terminal devices participating in a conference. A speaker identification means for identifying the terminal device of the speaker in the terminal device, and a speaker notification message in which information of the terminal device of the speaker identified by the speaker identification device is written to the edge device. Transmitting means, a means for receiving a packet from the terminal device, a filter means for discarding a packet and rewriting an address for the packet received by the receiving means, and a filter by the filter means A multicast packet that sends the packet with the destination of the packet not discarded after processing as the multicast address Communication means, means for receiving a speaker notification message from the center device, and means for recognizing the speaker according to the speaker notification message received by the means for receiving the speaker notification message, wherein the filter means Means for discarding packets from the terminal device other than the speaker recognized by the recognizing means, wherein the multicast packet transmitting means retransmits a packet received from the terminal device of the speaker recognized by the recognizing means. A multipoint conference apparatus comprising means for setting a destination as a multicast address and transferring the address to another apparatus. 2. The apparatus according to claim 1, wherein the means for transferring to another device includes means for transferring to the terminal device, and wherein the terminal device includes means for receiving a packet transferred by the multicast packet transmitting means. The multipoint conference device according to the above. 3. The means for transferring to another device includes means for transferring to another edge device, wherein the edge device has means for receiving a packet transferred by the multicast packet transmitting means, 2. The multipoint conference apparatus according to claim 1, further comprising: means for copying packets received by the receiving means for the number of terminals connected thereto. 4. An edge device for acquiring information for identifying a speaker from a packet received from the terminal device, and a unit for transmitting a message in which the acquired information is written to a center device. The center device includes a unit that receives the message from the edge device, and the speaker identification unit identifies a speaker based on information for identifying the speaker indicated in the message. 2. The multipoint conference apparatus according to claim 1, further comprising means for identifying.