JP2005333446A - Teleconference system, teleconference method, and communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conference system 10 for simply performing a teleconference without using MCUs, or the like. <P>SOLUTION: One of a plurality of communication terminals 100 for performing teleconferences is a management terminal for managing the teleconference. The management terminal refers to a teleconference management table 130 for managing the connection state of each call of the plurality of communication terminals 100, and establishes the call between the communication terminal 100 that establishes a call only with one of the plurality of communication terminals 100 and the communication terminal 100 that does not establish any calls with any of the plurality of communication terminals 100, thus enabling the communication terminal 100 that does not establish any calls with any of the plurality of communication terminals 100 to participate in the teleconference. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technology for performing a conference using a plurality of communication terminals.

  In recent years, multipoint communication conferences that connect multiple points via a communication network such as the Internet or ISDN and exchange video, audio, computer data, and the like have become widespread. In these multipoint communication conferences, a large-scale conference server device called MCU (Multipoint Connection Unit) or a central device is set, and each conference terminal transmits video and audio to the conference server device. Communication between multiple points is realized by relaying received video and audio to other conference terminals (for example, see Patent Document 1).

JP 2003-18302 A

  However, when such a multipoint communication conference is performed, it is necessary to separately provide an MCU or the like in addition to the communication terminals of the conference participants, and the multipoint communication conference may not be easily performed. In addition, since such an MCU synthesizes voices from a large number of communication terminals in real time, high processing capability is required, and the MCU may be expensive. Therefore, it may be costly to conduct a multipoint communication conference.

  The present invention has been made in view of the above circumstances, and an object of the present invention is that an MCU or the like is not required, and a multipoint communication conference can be easily and inexpensively performed only by a communication terminal of a conference participant. Is to make it.

  In order to solve the above-mentioned problem, the present invention refers to a communication conference management table that manages the connection state of each call of a plurality of communication terminals having a three-way communication function, and one of the plurality of communication terminals By establishing a call between a communication terminal that has established a call only with a communication terminal that has not established a call with any of the plurality of communication terminals, communication is performed by connecting the plurality of communication terminals in a chain. Realize the meeting.

  For example, in a conference system having a plurality of communication terminals, one of the plurality of communication terminals is a management terminal that manages calls between the plurality of communication terminals, and each of the plurality of communication terminals is A call processing means for establishing a call with each of one or two of the plurality of communication terminals, and the communication terminal via a call established by the call processing means Voice processing means for transmitting and receiving voice signals in the case where the call processing means establishes a call only with one communication terminal of the plurality of communication terminals by the call processing means. A voice signal input through a call with the one communication terminal is output from a speaker, and a voice signal input into the microphone is transmitted through a call with the one communication terminal; The plurality of communication terminals by call processing means When a call is established between each of the two communication terminals, the audio signals input through the calls of the two communication terminals are combined and output from the speaker. The voice signal input to the microphone and the voice signal input via a call with one of the two communication terminals are combined to provide the other communication terminal of the two communication terminals. And the voice signal input to the microphone and the voice signal input via the call with the other communication terminal are combined and transmitted to the call with the one communication terminal, The management terminal establishes a call with only one of the plurality of communication terminals by referring to the communication conference management table for managing the connection state of each call of the plurality of communication terminals and the management table. Communication terminal Providing a conference system, characterized in that it comprises a connection management means for establishing a call between the communication terminals that do not establish with any call of the communication terminal.

  According to the present invention, a multipoint communication conference can be realized easily and inexpensively by using only the communication terminals of conference participants without separately providing an MCU or the like.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a configuration diagram of a conference system 10 according to an embodiment of the present invention. The conference system 10 includes a plurality of communication terminals 100A to 100D and a communication network 12. The communication network 12 is, for example, the Internet, a dedicated line of a communication carrier, an in-house LAN, or the like. Each of the plurality of communication terminals 100 </ b> A to 100 </ b> D is, for example, an IP phone, is connected to the communication network 12, and communicates with each other via the communication network 12. Each of the plurality of communication terminals 100 </ b> A to 100 </ b> D enables a communication conference by the users of the plurality of communication terminals 100 </ b> A to 100 </ b> D by transmitting and receiving the user's voice and / or the user's image.

  FIG. 2 is a block diagram illustrating an example of the configuration of the communication terminal 100. The communication terminal 100 includes an audio input / output unit 102, a display unit 104, a key input unit 106, an audio mixer unit 108, a main control unit 110, an RTP processing unit 112, an SIP processing unit 114, a TCP / UDP / IP processing unit 116, and An interface unit 118 is provided. The interface unit 118 transmits / receives a frame storing IP packets to / from a communication partner via the communication network 12 by, for example, Ethernet (registered trademark).

  The TCP / UDP / IP processing unit 116 performs processing defined in TCP / UDP / IP. Specifically, a TCP packet or a UDP packet is extracted from the IP packet received from the interface unit 118, and further, an RTP packet and a SIP packet are extracted from the TCP packet or the UDP packet, and the RTP processing unit 112 and the SIP processing unit 114, respectively. To pass. The RTP packet received from the RTP processing unit 112 and the SIP packet received from the SIP processing unit 114 are stored in a TCP packet or a UDP packet, further stored in an IP packet, and passed to the interface unit 118.

  A SIP (Session Initiation Protocol) processing unit 114 performs processing such as call establishment and disconnection in accordance with a VoIP call control procedure defined in SIP. Specifically, the call control message stored in the SIP packet received from the TCP / UDP / IP processing unit 116 is analyzed, and the result is notified to the main control unit 110. In addition, a SIP packet storing a call control message is generated in accordance with an instruction from the main control unit 110 and passed to the TCP / UDP / IP processing unit 116. Thereby, the SIP processing unit 114 establishes a voice path (call) with the other one communication terminal 100. Note that the SIP processing unit 114 of the present embodiment can perform a three-party call by simultaneously establishing two voice paths with each of the other two communication terminals 100.

  An RTP (Real-time Transport Protocol) processing unit 112 performs processing defined in RTP on a call signal such as a voice signal. Specifically, the RTP packet is received from the TCP / UDP / IP processing unit 116, the RTP session is controlled according to the process defined in RTP, and the audio signal is restored from the received RTP packet. When the communication terminal 100 is performing a three-way call by establishing a call with the other two communication terminals 100, the RTP processing unit 112 transmits the audio signal restored from each audio path to the audio mixer. When the communication terminal 100 has established a call with only one communication terminal 100, the restored audio signal is output to the audio input / output unit 102. Further, when the communication terminal 100 is carrying out a three-party call, it receives an audio signal from the audio mixer unit 108, and when the communication terminal 100 establishes a call with only one communication terminal 100, the audio An audio signal from the input / output unit 102 is received. Then, the RTP processing unit 112 converts the received audio signal into an RTP packet and passes it to the TCP / UDP / IP processing unit 116.

  The voice input / output unit 102 samples the voice input from the microphone and converts it into digital data. Then, depending on whether the communication terminal 100 has established a call with two communication terminals 100 or only with one communication terminal 100, the converted digital data is processed by the audio mixer 108 or RTP processing. Send to section 112. The audio input / output unit 102 converts the digital data audio signal received from the audio mixer unit 108 or the RTP processing unit 112 into an analog signal and outputs the analog signal to the speaker.

  The voice mixer unit 108 realizes a three-party call by synthesizing voices transmitted and received between the three parties with the other two communication terminals 100. Specifically, after the voice path is established between each of the two other communication terminals 100 by the SIP processing unit 114, the voice mixer unit 108 passes through the RTP processing unit 112 from each voice path. The audio signals are received, and the received audio signals are synthesized and output to the speaker by the audio input / output unit 102. Also, a voice signal from a voice path established with one communication terminal 100 on the other side is synthesized with a voice signal received from the voice input / output unit 102 via a microphone, and the other communication terminal 100 is synthesized. The audio signal received from the audio input / output unit 102 via the microphone and the audio input / output unit 102 is transmitted to the audio path to the other communication terminal 100 and the audio signal received from the audio path to the other communication terminal 100 And transmitted to one of them.

  The display unit 104 displays a call state and the like to the user of the communication terminal 100. The display unit 104 may display an image based on the image signal transmitted in synchronization with the audio signal. The key input unit 106 receives a user operation (key operation, hook operation, etc.) input via an operation panel or the like.

  The main control unit 110 includes a communication conference management table 130 that stores information indicating whether or not it is a management terminal, together with information for managing call connection statuses of a plurality of other communication terminals 100 participating in the communication conference. And a connection destination management table 132 for managing which of the other communication terminals 100 has established a call. Detailed operation of the main control unit 110 will be described later.

  Note that each configuration of the communication terminal 100 described above may be implemented by an integrated logic IC such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA), or may be implemented by a DSP (Digital Signal). It may be executed by a computer such as a processor.

  FIG. 3 is a conceptual diagram illustrating an example of a detailed configuration of the audio mixer unit 108. The audio mixer unit 108 includes a jitter buffer 120A, a jitter buffer 120B, an adder 122, an adder 124, and an adder 126. The jitter buffer 120A and the jitter buffer 120B are provided corresponding to the voice path a and the voice path b for transmitting and receiving a voice signal and the like via the communication network 12, respectively, and the jitter of the voice signal received from the corresponding voice path. Absorb. Specifically, the audio signal from the corresponding audio path received from the RTP processing unit 112 is output at a predetermined timing according to the time stamp of the RTP packet including the audio signal.

  The adder 122 synthesizes the audio signal output from the jitter buffer 120 </ b> A and the audio signal received from the microphone of the communication terminal 100 via the audio input / output unit 102 and outputs the result to the audio path b. The adder 126 synthesizes the audio signal output from the jitter buffer 120B and the audio signal received from the microphone of the communication terminal 100 via the audio input / output unit 102, and outputs the synthesized audio signal to the audio path a. The adding unit 124 combines the audio signals output from the jitter buffers 120A and 120B, and sends the combined audio signal to the audio input / output unit 102, so that it is output from the speaker of the communication terminal 100. In this way, the communication terminal 100 according to the present embodiment performs a three-way call with the two communication terminals 100 as communication partners via the communication network 12.

  FIG. 4 shows an example of the structure of data stored in the communication conference management table 130. The communication conference management table 130 includes identification information 1308 for each of the plurality of communication terminals 100 participating in the communication conference, and identification information for a management terminal that manages the connection status of each call of the plurality of communication terminals 100 participating in the communication conference. 1306 is stored in association with identification information 1302 and 1304 of the communication terminal 100 of the other party with which each communication terminal 100 has established a call. In the communication conference management table 130, when the communication terminal 100 having the communication conference management table 130 is not a management terminal, all identification information stored in the communication conference management table 130 is cleared. The main control unit 110 can recognize whether or not it is a management terminal by referring to whether or not the identification information is stored in the communication conference management table 130. Further, by referring to the communication conference management table 130, it is recognized which of the plurality of communication terminals 100 participating in the communication conference has established a call with only one communication terminal 100. can do.

  FIG. 5 shows an example of the structure of data stored in the connection destination management table 132. The connection destination management table 132 stores identification information 1324 and 1326 of the counterpart communication terminal 100 with which the call has been established. By referring to the connection destination management table 132, the main control unit 110 can recognize whether or not it is carrying out a three-way call and recognizes which communication terminal 100 has established a call. can do.

  FIG. 6 is a flowchart illustrating an example of the operation of the main control unit 110. For example, the operation of the main control unit 110 shown in the flowchart starts at a predetermined timing such as when the power is turned on to the communication terminal 100, and the flowchart shows the predetermined timing such as when the supply of power is stopped. The operation of the main control unit 110 stops. First, the main control unit 110 indicates that the SIP processing unit 114 should establish a new call with the communication terminal 100 or a message indicating that the current connection destination should be changed from the management terminal. It is determined whether or not a message has been received (S100). When the message that the current connection destination should be changed or the message that the call should be newly established with the designated communication terminal 100 has not been received (S100: No), the SIP processing unit 114 It is determined whether or not a message indicating that the connection destination has been changed has been received from another communication terminal 100 (S102). When the SIP processing unit 114 has not received a message indicating that the connection destination has been changed (S102: No), the main control unit 110 receives the identification information of the other communication terminal 100 via the key input unit 106. By receiving it, it is determined whether or not a call for participation that causes another communication terminal 100 to participate in the communication conference has been accepted (S104). When the call for participation has not been received (S104: No), the main control unit 110 determines whether or not it has received a request to leave the communication conference via the key input unit 106 (S106). If a withdrawal request has not been accepted (S106: No), the process returns to step 100.

  In step 100, when the SIP processing unit 114 receives a message indicating that the current connection destination should be changed or a message indicating that a call should be newly established with the designated communication terminal 100 (S100: Yes). ) Based on the received message, the main control unit 110 changes the connection destination to the SIP processing unit 114 or makes a new call with the designated communication terminal 100 in accordance with the call control procedure defined in SIP. Establish (S108). Then, the main control unit 110 updates the connection destination management table 132 according to the identification information of the changed communication terminal 100 of the connection destination or the communication terminal 100 of the other party that has newly established a call (S110), and then the step 100 Return to.

  In step 102, when the SIP processing unit 114 receives a message indicating that the connection destination has been changed (S102: Yes), the main control unit 110 stores the message in the communication conference management table 130 based on the received message. By changing the connection destination of the corresponding communication terminal 100, the communication conference management table 130 is updated (S112), and then the process returns to step 100. Thereby, when the communication terminal itself is the management terminal of the communication conference, the call connection state of the other communication terminals 100 participating in the communication conference can always be kept up-to-date.

  If a call for participation is accepted in step 104 (S104: Yes), the main control unit 110 currently makes a three-way call by establishing a call with two other communication terminals 100. Is determined (S114). When oneself is making a three-party call (S114: Yes), the main control unit 110 refers to the communication conference management table 130 and establishes a call with only one communication terminal 100. 100 or a message for establishing a call to a communication terminal 100 to be newly joined to a communication conference specified by the input identification information is transmitted, so that a call is established only with one communication terminal 100. A call is established between another communication terminal 100 and the communication terminal 100 to be newly joined to the communication conference, and the communication terminal 100 to be newly joined to the communication conference is joined to the communication conference (S118). The management table 130 is updated (S112).

  In Step 104, if the terminal itself has not established a call with any other communication terminal 100, or has established a call only with one other communication terminal 100 (S114: No), the main control is performed. The unit 110 controls the SIP processing unit 114 to transmit a message for establishing a call to another communication terminal 100 that has not established a call with any of the communication terminals 100, so that the communication with the communication terminal 100 is established. The call is established, the communication terminal 100 is made to participate in the communication conference (S116), and the communication conference management table 130 is updated (S112). In this embodiment, it is only the management terminal that can hold a communication conference by calling the communication terminal 100 of the participant of the communication conference to participate. Therefore, steps 114, 116, and 118 are operations performed only by the management terminal.

  If a withdrawal request is accepted in step 106 (S106: No), the main control unit 110 refers to the communication conference management table 130 and determines whether or not it is a management terminal (S120). When the terminal itself is a management terminal (S120: Yes), the communication conference management table 130 is referred to and all other communication terminals 100 participating in the communication conference are called via the SIP processing unit 114. A message for instructing disconnection is transmitted (S122). Then, the main control unit 110 clears the contents of the communication conference management table 130 (S124), and then returns to step 100.

  In step 120, when the terminal itself is not the management terminal (S120: No), the main control unit 110 refers to the connection destination management table 132 and determines whether or not the terminal itself is in a three-party call (S126). . When it is in a three-party call (S126: Yes), the main control unit 110 controls the SIP processing unit 114 to transfer one call to the other of the two connected communication terminals 100. The message is transmitted to both of the two communication terminals 100, and the call to the two communication terminals 100 is disconnected by transmitting a message indicating that the call is disconnected to the two communication terminals 100. (S128). Then, the main control unit 110 clears the connection destination management table 132 (S132), and then returns to Step 100. In step 126, when the call control unit 110 establishes a call only with one other communication terminal 100 (S126: No), the main control unit 110 controls the SIP processing unit 114 to establish a call. The call with the partner communication terminal 100 is disconnected (S130), and the connection destination management table 132 is cleared (S132).

  In this example, the management terminal recognizes all the identification information of the plurality of communication terminals 100 participating in the communication conference by input from the user or the like. When a communication conference is held, the management terminal establishes a call with another communication terminal 100 participating in the communication conference, either directly or indirectly through another communication terminal 100 participating in the communication conference. As another example, the management terminal always participates in a communication conference by establishing one call with one other communication terminal 100, and is on the way to the communication conference by the other call. An offer of participation from another participating communication terminal 100 may be accepted. In this case, the communication terminal establishes a call with only one communication terminal 100 by referring to the communication conference management table 130 for the call established with the communication terminal 100 participating in the communication conference halfway. By transferring to the terminal 100, it is possible to always accept an offer to join a communication conference from another communication terminal 100.

  FIG. 7A is a conceptual diagram for explaining the operation of the communication terminal 100 when a communication conference is performed by the three communication terminals 100. In the figure, solid arrows indicate the flow of SIP packets, and dotted arrows indicate the flow of RTP packets having voice signals. In this example, the user of the communication terminal 100A is a communication conference organizer. The communication terminal 100A used by the organizer of the communication conference is a management terminal that manages calls of the plurality of communication terminals 100 participating in the communication conference.

  Communication terminal 100A establishes a call with each of communication terminals 100B and 100C according to a communication procedure defined in SIP. The communication terminal 100A synthesizes the voice signal of the user of the communication terminal 100A with the voice signal received from the communication terminal 100B, sends the synthesized voice signal to the communication terminal 100C, and transmits the synthesized voice signal to the voice signal received from the communication terminal 100C. The voice signal of the user 100A is synthesized and the synthesized voice signal is sent to the communication terminal 100B. Furthermore, the audio signals from communication terminals 100B and 100C are synthesized and output from the speaker of communication terminal 100A. The communication terminal 100B outputs the synthesized voice signals of the user of the communication terminal 100A and the user of the communication terminal 100C received from the communication terminal 100A from the speaker of the communication terminal 100B, and also receives the voice of the user of the communication terminal 100B received via the microphone. Is transmitted to the communication terminal 100A. The communication terminal 100C outputs a synthesized voice signal of the user of the communication terminal 100A and the user of the communication terminal 100B received from the communication terminal 100A from the speaker, and outputs the voice of the user of the communication terminal 100C received via the microphone to the communication terminal 100A. Send to. In this way, a communication conference is performed by the plurality of communication terminals 100A, 100B, and 100C. In the call establishment state as shown in FIG. 7A, the contents of the communication conference management table 130 included in the communication terminal 100A as the management terminal are as shown in FIG. 7B.

  FIG. 8A is a conceptual diagram for explaining the operation of the communication terminal 100A when the communication terminal 100D newly participates in the ongoing communication conference. When the communication terminal 100D newly participates in the ongoing communication conference, the communication terminal 100D notifies, for example, that the communication terminal 100A is participating in the communication conference organizer. The communication terminal 100A refers to the communication conference management table 130 and extracts the communication terminal 100 that has established a call with only one communication terminal 100. In this example, the communication terminal 100A extracts, for example, the communication terminal 100B as the communication terminal 100 that has established a call with only one communication terminal 100. Then, communication terminal 100A transmits a message to instruct communication terminal 100B to establish a call with communication terminal 100D.

  When a call between the communication terminal 100B and the communication terminal 100D is established, the communication terminal 100B synthesizes a voice signal of the user of the communication terminal 100B with a voice signal from the communication terminal 100D and transmits the synthesized voice signal to the communication terminal 100A. The voice signal from terminal 100A is synthesized with the voice signal of the user of communication terminal 100B and sent to communication terminal 100D. Furthermore, the audio signals from communication terminals 100A and 100D are synthesized and output from the speaker of communication terminal 100B. At this time, the audio signal from communication terminal 100A is a combination of the audio signal of the user of communication terminal 100A and the audio signal from communication terminal 100C. The communication terminal 100D outputs a synthesized voice signal of the user of the communication terminal 100A, the user of the communication terminal 100B, and the user of the communication terminal 100C received from the communication terminal 100B from the speaker, and also receives the communication terminal 100D received via the microphone. The user's voice is transmitted to communication terminal 100B. Thereby, a communication conference can be performed between the four parties using only the communication terminal 100 having the three-party call function.

  When a new communication terminal 100D participates in the communication conference, the communication terminal 100A, which is the terminal of the communication conference organizer, adds the communication terminal 100D to the communication conference management table 130 and establishes a call with the communication terminal 100D. By updating the connection status of the communication terminal 100B, the connection status of each of the communication terminals 100 participating in the communication conference is kept up to date. As a result, in the call establishment state as shown in FIG. 8A, the contents of the communication conference management table 130 included in the communication terminal 100A as the management terminal are as shown in FIG. 8B.

  Similarly, when a communication terminal 100N that has not established a call with any communication terminal 100 participates in the communication conference, the communication terminal 100A refers to the communication conference management table 130 and makes a call with only one communication terminal 100. By extracting the established communication terminal 100 and causing the extracted communication terminal 100 to establish a call with the communication terminal 100N, the communication terminal 100N is allowed to participate in the communication conference.

  In this way, a communication conference can be realized between a plurality of communication terminals 100 by establishing a call in a chain form with a plurality of communication terminals 100 having a three-party call function. As a result, the communication conference can be easily realized only by the respective communication terminals 100 of the participants of the communication conference without separately providing devices such as MCUs. Further, if a communication conference is performed using a synthesis device such as an MCU that synthesizes a plurality of voice paths and distributes the synthesized voice signal to each communication terminal 100, the plurality of communication terminals 100 participating in the communication conference. Are all transmitted to the synthesizer. Therefore, a large-capacity communication line is required between the synthesis apparatus and the communication network 12. However, as described in the present embodiment, each communication terminal 100 only uses at most two voice paths, and therefore it is not necessary to provide a large-capacity communication line. Therefore, a communication conference can be realized at low cost.

  FIG. 9 is a sequence diagram illustrating an example of operations of the communication terminals 100A, 100B, and 100D when the communication terminal 100D newly participates in the ongoing communication conference. Prior to this sequence diagram, it is assumed that communication terminals 100A and 100B have established a call according to a call control procedure defined in SIP.

  First, the communication terminal 100A, which is a management terminal, transmits a SUBSCRIBE request, which is a request for notifying the communication terminals 100B and 100C when an event occurs, to the communication terminal 100B with the target event as a connection state ( S200). When the communication terminal 100D notifies the communication terminal 100A of participation in the communication conference, the communication terminal 100A refers to the communication conference management table 130 and establishes a call with only one communication terminal 100. 100B is extracted.

  The communication terminal 100A sets the reference destination as the communication terminal 100D and transmits a REFER request to the communication terminal 100B, thereby causing the communication terminal 100B to start establishing a call to the communication terminal 100D (S202). Note that the REFER request in step 202 includes the message that the connection destination should be changed described in step 100 in FIG. 6 and the call that is established only with one communication terminal 100 described in step 118. Correspond to a message for establishing a call between the other communication terminal 100 and another communication terminal 100 that has not established a call.

  Next, the communication terminal 100B transmits an ACCEPTED response indicating that the REFER request has been accepted to the communication terminal 100A (S204). The communication terminal 100B starts call establishment by transmitting an INVITE request to the communication terminal 100D (S206). In addition, the communication terminal 100B transmits a NOTIFY request to the communication terminal 100A with the progress information as 100 Trying indicating that a call establishment is being attempted (S208). Then, the communication terminal 100A transmits a 200 OK response, which is a final response to the NOTIFY request, to the communication terminal 100B (S210).

  The communication terminal 100D transmits a 100 Trying response, which is an intermediate response indicating that a call establishment attempt is being made, to the communication terminal 100B (S212). Then, the communication terminal 100D outputs IR (Interrupted Ringing) from the voice input / output unit 102 (S214), and transmits 180 Ringing, which is an intermediate response indicating that a call is being made, to the communication terminal 100B (S216). Then, the communication terminal 100B transmits a NOTIFY request to the communication terminal 100A with the progress information as 180 Ringing (S218). Then, the communication terminal 100A transmits a 200 OK response to the NOTIFY request from the communication terminal 100B to the communication terminal 100B (S220).

  When communication terminal 100D accepts a response operation such as off-hook via key input unit 106 (S222), communication terminal 100D transmits a 200 OK response to the INVITE request from communication terminal 100B to communication terminal 100B (S224). Then, the communication terminal 100B transmits an ACK request notifying that the final response to the INVITE request has been received to the communication terminal 100D (S228). The communication terminal 100B sets the progress information to 200 OK, transmits a NOTIFY request to the communication terminal 100A (S226), and receives a 200 OK response to the transmitted NOTIFY request from the communication terminal 100A (S230). Communication terminal 100B then establishes a three-party call between communication terminal 100A and communication terminal 100D, and synthesizes the voice signal of user of communication terminal 100B with the voice signal from communication terminal 100D. And the voice signal from the communication terminal 100A is synthesized with the voice signal of the user of the communication terminal 100B and sent to the communication terminal 100D (S232). Thereby, communication terminal 100D can participate in the communication conference currently performed by communication terminals 100A-C.

  Next, the communication terminal 100B sends a NOTIFY request including information indicating that the call connection state with only the communication terminal 100 has changed to the call connection state with the communication terminal 100A and the communication terminal 100D to manage the communication conference. The communication terminal 100A, which is a terminal, is transmitted (S234), and a 200 OK response to the transmitted NOTIFY request is received from the communication terminal 100A (S236). Note that the NOTIFY request including information indicating that the call connection state has changed in step 234 corresponds to the message indicating that the connection destination has been changed, which has been described in step 102 in FIG.

  The communication terminal 100A updates the communication conference management table 130 by changing the connection destination of the communication terminal 100B and adding the communication terminal 100D based on the connection state of the call received from the communication terminal 100B (S238). . Then, the communication terminal 100A transmits a SUBSCRIBE request for setting the target event to the connected state to the communication terminal 100D newly participating in the communication conference (S240).

  FIG. 10 is a sequence diagram illustrating an example of operations of the communication terminals 100A, 100B, and 100D when the communication terminal 100B leaves the communication conference. Prior to this sequence diagram, it is assumed that communication terminals 100A, 100B, and 100C establish a call and perform a communication conference in the procedure described in FIG.

  When the communication terminal 100B leaves the communication conference, first, the communication terminal 100B includes information indicating that the call with the communication terminal 100B is replaced with the call with the communication terminal 100D, and the REFER with the reference destination as the communication terminal 100D. The request is transmitted to communication terminal 100A (S300). Then, the communication terminal 100A transmits an ACCEPTED response indicating that the REFER request has been accepted to the communication terminal 100B (S302). Note that the REFER request in step 300 corresponds to the message for transferring one call to the other described in step 128 in FIG.

  Next, the communication terminal 100A transmits an INVITE request including information indicating that the call with the communication terminal 100B is replaced with the call with the communication terminal 100D to the communication terminal 100D (S306), and during the establishment of the call A NOTIFY request with 100 Trying indicating progress as progress information is transmitted to the communication terminal 100B (S304). Then, the communication terminal 100B transmits a 200 OK response to the NOTIFY request to the communication terminal 100A (S308). In addition, the communication terminal 100D transmits a 100 Trying response to the communication terminal 100A (S310).

  Next, the communication terminal 100D transmits a BYE request for requesting call disconnection to the communication terminal 100B (S312). Then, the communication terminal 100B transmits a 200 OK response to the BYE request to the communication terminal 100D (S314), whereby the call between the communication terminal 100B and the communication terminal 100D disappears (S316). Note that the BYE request in step 312 corresponds to the message indicating disconnection of the call described in step 128 in FIG.

  Next, the communication terminal 100D transmits a 200 OK response to the INVITE request from the communication terminal 100A to the communication terminal 100A (S318). Then, the communication terminal 100A transmits an ACK request to the communication terminal 100D (S320), thereby establishing a call between the communication terminal 100A and the communication terminal 100D (S322). Then, the communication terminal 100A sets the progress information to 200 OK, transmits a NOTIFY request to the communication terminal 100B (S324), and receives a 200 OK response to the transmitted NOTIFY request from the communication terminal 100B (S326). Thereby, the communication terminal 100B knows that a call has been established between the communication terminal 100A and the communication terminal 100D, and transmits a BYE request to the communication terminal 100A (S328). Then, when the communication terminal 100A transmits a 200 OK response to the BYE request to the communication terminal 100B (S330), the call between the communication terminal 100A and the communication terminal 100B disappears (S332). Note that the BYE request in step 328 corresponds to the message indicating that the call is to be disconnected described in step 128 in FIG.

  Next, the communication terminal 100D is a communication conference management terminal for a NOTIFY request including information indicating that the call connection state with only the communication terminal 100B has changed to the call connection state with only the communication terminal 100A. It transmits to the communication terminal 100A (S334). Note that the NOTIFY request including information indicating that the call connection state has changed in step 334 corresponds to the message indicating that the connection destination has been changed, described in step 102 of FIG.

  Then, the communication terminal 100A transmits a 200 OK response to the NOTIFY request to the communication terminal 100D (S336), changes the connection destination of the communication terminal 100D based on the connection state of the call received from the communication terminal 100D, and The communication conference management table 130 is updated by deleting the communication terminal 100B (S338). By such an operation, the communication terminal 100B can be disconnected from the communication conference without disconnecting the audio signal from the communication terminal 100D during the communication conference.

  In this example, the communication terminal 100B to leave leaves the communication terminal 100A to instruct the transfer to start the removal process, but instructs any communication terminal 100 on the other party of the three-party call to transfer. Accordingly, the separation process may be started. However, even in this case, it is necessary to send a NOTIFY request for notifying the connection status to the communication terminal 100A, which is the management terminal, after the withdrawal process is completed.

  Also, in this example, a case has been described in which the communication terminal 100B that is performing a three-way call between the communication terminal 100A, which is the management terminal, and another terminal leaves, but a direct call has not been established with the management terminal. Even when the communication terminal 100 leaves the communication conference, the leaving process shown in this sequence diagram is performed between the leaving communication terminal 100 and the leaving communication terminal 100 and the communication terminal 100 having a three-way call. Can be applied.

  In the above embodiment, the case where SIP is used as the call control protocol has been described as an example. However, the call control protocol is not limited to this, and HTC 323 of the TTC (The Telecommunication Technology Committee) standard is used for the call control procedure. Even when used, the present invention can be similarly applied.

  The embodiment of the present invention has been described above.

  As described above, according to the present embodiment, a multipoint communication conference can be realized easily and inexpensively by using only the communication terminals of the conference participants without separately providing devices such as MCUs.

  In addition, this invention is not limited to said embodiment, Many deformation | transformation are possible within the range of the summary.

  FIG. 11 is a configuration diagram illustrating another example of the conference system 10. In this example, each of the plurality of communication terminals 100 has a function of performing a multi-party call with a plurality of other communication terminals 100. Specifically, each of the plurality of communication terminals 100 establishes a call with (m−1) communication terminals 100 (m is a natural number), and (m−1) in the voice paths An audio signal from an audio path other than the kth audio path and an audio signal from its own microphone are synthesized and transmitted to the kth audio path to the kth audio path (k is a natural number equal to or less than m). At the same time, it has a function of realizing m-party call by synthesizing audio signals from (m−1) audio paths and outputting them from its own speaker.

  In this example, the communication terminal 100C receives voices D, E, F, and G, which are voice signals from voice paths other than the voice path with the communication terminal 100A, and voice signals from the microphone of the communication terminal 100C. Combined and transmitted to communication terminal 100A. In addition, the communication terminal 100C synthesizes voices A, B, and E, which are voice signals from voice paths other than the voice path with the communication terminal 100D, and voice signals from the microphone of the communication terminal 100C, It transmits to communication terminal 100D. Furthermore, the communication terminal 100C receives voices A, B, D, F, and G, which are voice signals from voice paths other than the voice path with the communication terminal 100E, and voice signals from the microphone of the communication terminal 100C. Combined and transmitted to communication terminal 100A. Thereby, several communication terminal 100A-G can implement | achieve a communication conference.

  According to this example, since the number of communication terminals 100 that relay the audio signal from each communication terminal 100 can be reduced, the delay amount of the audio signal can be reduced. Therefore, a communication conference can be performed using more communication terminals 100.

  In this example, each of the plurality of communication terminals 100 is preferably configured so that the voice paths are not connected in a loop.

  The management terminal that manages the calls of the plurality of communication terminals 100A to 100G is associated with the capacity of the communication line connected to the communication network 12 by each of the plurality of communication terminals 100A to 100G. It is preferable to manage each call of terminals 100A-G. Specifically, in FIG. 11, when the capacity of the communication line between the communication terminals 100D and 100G is larger than the capacity of the communication line between the communication terminals 100D and 100F, a call is made to any of the communication terminals 100. When the communication terminal 100 that has not been established newly participates in the communication conference, the management terminal establishes a call to the communication terminal 100 that newly participates in the communication terminal 100G having a large-capacity communication line. A new communication terminal 100 is allowed to participate in the conference. Thereby, the probability that the audio signal of the communication conference is delayed can be suppressed by causing data other than the communication conference to flow through the communication line used in the communication conference. Therefore, audio signals can be transmitted and received more stably.

1 is a configuration diagram of a conference system 10 according to an embodiment of the present invention. 2 is a block diagram illustrating an example of a configuration of a communication terminal 100. FIG. 3 is a conceptual diagram illustrating an example of a detailed configuration of an audio mixer unit 108. FIG. It is a figure which shows an example of the structure of the data stored in the communication meeting management table. It is a figure which shows an example of the structure of the data stored in the connection destination management table. 3 is a flowchart showing an example of the operation of a main control unit 110. FIG. 7A is a conceptual diagram for explaining the operation of the management terminal when a communication conference is performed by the three communication terminals 100. FIG. 7B shows the contents of the communication conference management table 130 in the case shown in FIG. FIG. 8A is a conceptual diagram for explaining the operation of the communication terminal 100A when the communication terminal 100D newly participates in the ongoing communication conference. FIG. 8B shows the contents of the communication conference management table 130 in the case shown in FIG. It is a sequence diagram which shows an example of operation | movement of communication terminal 100A, 100B, and 100D in case communication terminal 100D newly participates in the communication conference currently being held. It is a sequence diagram which shows an example of operation | movement of communication terminal 100A, 100B, and 100D when the communication terminal 100B leaves | separates from a communication conference. It is a block diagram which shows the other example of the conference system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Conference system, 12 ... Communication network, 100 ... Communication terminal, 102 ... Voice input / output part, 104 ... Display part, 106 ... Key input part, 108 ... Voice Mixer unit, 110 ... main control unit, 112 ... RTP processing unit, 114 ... SIP processing unit, 116 ... TCP / UDP / IP processing unit, 118 ... interface unit, 120 ... Jitter buffer 122 ... adder 124 ... adder 126 + adder 130 ... communication conference management table 132 ... connection destination management table

Claims (6)

A communication conference system having a plurality of communication terminals,
One of the plurality of communication terminals is a management terminal that manages calls between the plurality of communication terminals,
Each of the plurality of communication terminals is
Call processing means for establishing a call with each of one or two of the plurality of communication terminals;
Voice processing means for transmitting and receiving voice signals to and from the communication terminal via a call established by the call processing means,
The voice processing means is
When a call is established only with one communication terminal of the plurality of communication terminals by the call processing means, an audio signal input through a call with the one communication terminal is An audio signal output from the speaker and input to the microphone is transmitted via a call with the one communication terminal,
If a call is established between each of the two communication terminals of the plurality of communication terminals by the call processing means, the voice input via the call of each of the two communication terminals A signal is synthesized and output from the speaker, and a voice signal input to the microphone and a voice signal input via a call with one of the two communication terminals are combined to generate the 2 Transmitting to a call with the other communication terminal of the two communication terminals, and combining the audio signal input to the microphone and the audio signal input via the call with the other communication terminal Send to call with one communication terminal,
The management terminal
A communication conference management table for managing a connection state of each call of the plurality of communication terminals;
Referring to the management table, between a communication terminal that has established a call with only one of the plurality of communication terminals and a communication terminal that has not established a call with any of the plurality of communication terminals. A communication conference system comprising connection management means for establishing a call. The connection management means further includes:
When a communication terminal that has established a call with two communication terminals of the plurality of communication terminals disconnects the call, the two communication terminals are referred to by referring to the communication conference management table The communication conference system according to claim 1, wherein the other call is transferred to any one of the above. A communication terminal having a three-party call function,
Identification information input means for receiving, from a user, identification information of a communication terminal that participates in a communication conference that transmits and receives audio to and from the plurality of communication terminals;
Call processing means for establishing a call with a communication terminal corresponding to the identification information input in the identification information;
A communication conference management table for managing a connection state of each call of the plurality of communication terminals;
A connection destination management table for managing which one of the plurality of communication terminals has established a call;
When the communication terminal is a management terminal that manages the communication terminals participating in the communication conference, the communication terminal refers to the communication conference management table and establishes a call with only one of the plurality of communication terminals. A communication terminal that has not established a call with any of the plurality of communication terminals is allowed to participate in the communication conference by establishing a call to a communication terminal that has not established a call with any of the plurality of communication terminals; Updating the teleconference management table;
A connection management means for establishing a call to the communication terminal instructed by the management terminal and updating the connection destination management table in response to an instruction from the management terminal when the terminal itself is not the management terminal A communication terminal characterized by. A communication terminal having a three-party call function,
When participating in a communication conference that transmits and receives audio to / from a plurality of the communication terminals, a leave instruction input unit that accepts from the user that the user leaves the communication conference;
A connection destination management table for managing which one of the plurality of communication terminals has established a call;
When the withdrawal instruction input means accepts from the user that the withdrawal instruction input means is withdrawn from the communication conference, by referring to the connection destination management table and disconnecting the call with the communication terminal of the other party that has established the call Call processing means for leaving the communication conference;
When leaving the communication conference, referring to the connection destination management table and establishing a call with two communication terminals, a three-way call is performed. When one call is transferred to the other and the connection destination management table is updated and a call is established only with one communication terminal, the call with the one communication terminal is disconnected. A communication terminal comprising: a connection management unit that leaves the communication conference and updates the connection destination management table. A communication conference method for performing a conference using a plurality of communication terminals including a management terminal,
Each of the plurality of communication terminals is
A call processing step for establishing a call with each of one or two of the plurality of communication terminals;
An audio processing step of transmitting and receiving an audio signal to and from the communication terminal via the call established by the call processing step,
The voice processing step includes
When a call is established only with one communication terminal of the plurality of communication terminals by the call processing step, an audio signal input through the call with the one communication terminal is An audio signal output from the speaker and input to the microphone is transmitted via a call with the one communication terminal,
When a call is established between each of the two communication terminals of the plurality of communication terminals by the call processing step, the voice input via the call of each of the two communication terminals A signal is synthesized and output from the speaker, and a voice signal input to the microphone and a voice signal input via a call with one of the two communication terminals are combined to generate the 2 Transmitting to a call with the other communication terminal of the two communication terminals, and combining the audio signal input to the microphone and the audio signal input via the call with the other communication terminal Send to call with one communication terminal,
The management terminal
Managing a call connection state of each of the plurality of communication terminals by a communication conference management table of the management terminal;
Referring to the management table, between a communication terminal that has established a call with only one of the plurality of communication terminals and a communication terminal that has not established a call with any of the plurality of communication terminals. A communication conferencing method comprising: a connection management step for establishing a call. The connection management step further includes:
When a communication terminal that has established a call with two communication terminals of the plurality of communication terminals disconnects the call, the two communication terminals are referred to by referring to the communication conference management table The communication conferencing method according to claim 5, wherein the other call is transferred to any one of the methods.

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