Voice communication system, voice communication method, and recording medium

Abstract

Provided is a voice communication system that notifies a terminal device of transmission restriction information when the number of received voice signals reaches a specified number. A server device always counts the number of simultaneous receptions of voice signals. A first terminal device sends a voice signal together with identification information of a second terminal device to the server device. The server device forwards the voice signal sent from the first terminal device to the second terminal device, but when the number of simultaneous receptions reaches a given limit value, the server device adds transmission restriction information to the received voice signal and forwards it to the second terminal device. While the second terminal device is receiving the voice signal to which the transmission restriction information is added, the second terminal device does not send a voice signal even if there is a transmission operation by the user.

Description

Technical Field

[0001] The present invention relates to limiting the number of simultaneously transmitted voice signals in a voice communication system using a network such as a wireless LAN. Background Art

[0002] Wireless LAN transceiver systems have been put into practical use. Voice communication systems such as wireless LAN transceiver systems have multiple terminal devices (transceivers) and server devices connected via a wireless LAN (local area network). The server device relays the communication between the terminal devices. The terminal device sends a voice signal to the server device. The server device that receives the voice signal forwards the voice signal to the terminal device of the communication partner. In the voice communication system, the characteristics of the wireless LAN can be effectively utilized to perform individual communication and group communication in full duplex. The terminal device has a shape similar to a portable transceiver, and the user can use it with the same sense of use as in previous wireless communications. Summary of the invention

[0003] -Problems to be solved by the invention-

[0004] In the above-mentioned voice communication system, the server device relays the communication of the pre-registered terminal device. When the scale of the voice communication system becomes larger, the number of registered terminal devices also increases. When a large number of terminal devices send voice signals to the server device at the same time, the processing capacity of the server device may be exceeded. When the number of voice signals exceeding the processing capacity is sent to the server device, the sound quality of the voice signal forwarded to the communication partner may be reduced or the sound may skip.

[0005] An object of the present invention is to provide a voice communication system which notifies a terminal device of limiting the transmission of voice signals when the number of received voice signals reaches a predetermined number.

[0006] -Methods for solving problems-

[0007] The voice communication system of the present invention comprises a server device and a plurality of terminal devices interconnected via a network. The voice communication system performs the following processing. The sender, i.e., the first terminal device, sends a voice signal and identification information of the communication counterpart (respondent), i.e., the second terminal device, to the server device according to the sending operation of the user. The server device forwards the voice signal sent from the first terminal device to the second terminal device. The server device always counts the number of simultaneous receptions of the voice signal. In other words, the number of simultaneous receptions is the number of terminal devices that send the voice signal. When the number of simultaneous receptions reaches a given limit value, the received voice signal is attached with the sending restriction information and is forwarded to the second terminal device. While the second terminal device is receiving the voice signal to which the sending restriction information is attached, the sending restriction is performed so that the voice signal is not sent even if there is a sending operation by the user.

[0008] The voice communication method of the present invention is a method in which a plurality of terminal devices, including a sender, i.e., a first terminal device, and a responder, i.e., a second terminal device, communicate with each other via a server device, wherein the server device is connected via a network, and includes the following steps. The first terminal device sends a voice signal and identification information of a communication partner, i.e., a second terminal device, to the server device in accordance with a user's sending operation. The server device forwards the voice signal sent from the first terminal device to the second terminal device. The server device always counts the number of simultaneous receptions of the voice signal. When the number of simultaneous receptions reaches a given limit value, the server device adds transmission restriction information to the received voice signal and forwards it to the second terminal device. While the second terminal device is receiving a voice signal to which the transmission restriction information is attached, the server device performs a transmission restriction so that the voice signal is not sent even if there is a user's sending operation.

[0009] The voice communication program of the present invention enables the control unit of a server device that communicates with a plurality of terminal devices including a first terminal device as a sender and a second terminal device as a responder via a network to function as the following units: a first unit that receives a voice signal sent from the first terminal device; a second unit that always counts the number of simultaneous receptions of the voice signal; and a third unit that forwards the received voice signal to the second terminal device, and when the number of simultaneous receptions reaches a given limit value, adds transmission restriction information to the received voice signal and forwards it to the second terminal device.

[0010] -Effects of the Invention-

[0011] According to the present invention, when the number of audio signals transmitted by a terminal device reaches a predetermined number, transmission restriction information can be transmitted to the terminal device to restrict the transmission of audio signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural diagram of a voice communication system as an embodiment of the present invention.

[0013] Figure 2 This is a diagram showing the structure of audio groups.

[0014] Figure 3 It is a block diagram of a terminal device.

[0015] Figure 4 It is a block diagram of a server device.

[0016] Figure 5 This is a diagram showing a terminal table set in a server device.

[0017] Figure 6 This is a diagram showing a group table set in a server device.

[0018] Figure 7 This is a diagram showing a session table set in a server device.

[0019] Figure 8 This is a diagram showing a transmission terminal table set in the server device.

[0020] Fig. 9 This is a flowchart showing the operation of the server device.

[0021] Fig.10 This is a flowchart showing the operation of the server device.

[0022] Fig.11 This is a flowchart showing the operation of the server device.

[0023] Fig.12 This is a flowchart showing the operation of the terminal device.

[0024] Fig.13 This is a flowchart showing the operation of the terminal device. DETAILED DESCRIPTION

[0025] The voice communication system of the present invention will be described with reference to the accompanying drawings. Figure 1 1 is a block diagram of a voice communication system as an embodiment of the present invention. In the voice communication system, a plurality of terminal devices 14 communicate with each other via a network 17. A server device 11 relays the communication. The terminal device 14 has a shape similar to a portable transceiver for wireless communication, such as Figure 3 As shown, a PTT (push-to-talk) switch 220 is provided. If the user presses the PTT switch 220 and simultaneously presses the microphone 240 (refer to Figure 3) speaks, the terminal device 14 transmits the sound signal input from the microphone 240 to the server device 11. The server device 11 forwards the sound signal received from the terminal device 14 to the terminal device 14 of the communication partner.

[0026] From a functional point of view, the terminal device 14 is a wireless network device that transmits and receives the voice packet 100 via the wireless access point (AP) 13. The network 17 is composed of a wired network 15 and a wireless LAN (local area network) 16 such as Wi-Fi (registered trademark). The server device 11 is connected to the wired network 15. The terminal device 14 communicates via the wireless LAN 16. The wireless access point 13 connects the wireless LAN 16 to the wired network 15.

[0027] As the wired network 15, a LAN of Ethernet (registered trademark), the Internet, etc. can be used. When communicating via the Internet, secure communication can be performed by using a VPN (Virtual Private Network). In addition, as the wireless LAN 16, a communication method based on IEEE802.11 such as Wi-Fi can be applied. The terminal device 14 and the wireless access point 13 communicate through the communication method of the wireless LAN 16. Figure 1 In the example, three wireless access points 13 are provided, but the number of wireless access points 13 is not limited in the voice communication system.

[0028] In the voice communication system, voice communication is performed according to the following steps. When the PTT switch 220 is pressed, the terminal device 14 sends a voice signal without a prior communication establishment step. The server device 11 receives the voice signal sent from the terminal device 14 without a prior communication establishment step. Communication control information is attached to the sent voice signal. Based on the communication control information, the server device 11 forwards the voice signal to the terminal device 14 of the communication partner. Through the above steps, in the voice communication system, although it is voice communication via the network 17, there is no need for a communication establishment step such as the SIP step. As a result, the user can perform voice communication via the network 17 by turning on the PTT switch 220 of the terminal device 14 and emitting sound to the microphone 240, just like a conventional wireless communication transceiver.

[0029] The terminal device 14 and the server device 11 packetize the voice signal and transmit and receive it via the network 17. Since packet communication is intermittent communication, the terminal device 14 can perform full-duplex communication in which the voice signal is received in parallel with the transmission of the voice signal. However, the terminal device 14 transmits the voice signal only when the PTT switch 220 is pressed, so that the voice signal is not always continuously transmitted. The terminal device 14 also receives the voice signal of the terminal device 14 of the communication partner during the process of transmitting the voice signal by pressing the PTT switch 220, and the voice is output from the speaker 241.

[0030] In this voice communication system, three communication modes are performed, namely, individual communication, group communication, and overall communication. Individual communication is a one-to-one communication mode in which one terminal device 14 calls another terminal device 14 and communicates with each other. Hereinafter, the terminal device 14 that calls the other party of communication is referred to as the calling terminal device 14. Group communication is a communication mode in which the calling terminal device 14 calls a group to which a plurality of terminal devices 14 belong, and the calling terminal device 14 communicates with the terminal devices 14 belonging to the called group. Overall communication is a group communication with all terminal devices 14 as the target, and is a communication mode in which the calling terminal device 14 calls all, and all terminal devices 14 communicate with each other.

[0031] A plurality of terminal devices 14 are registered (accommodated) in the server device 11. The registered terminal devices 14 can perform voice communication via the server device 11. When there are many users, a large number (e.g., 3,000) of terminal devices 14 are registered in the server device 11, but the number of registered devices may exceed the simultaneous communication processing capacity of the server device 11. For example, it is assumed that the number of voices that the server device 11 can process simultaneously (the maximum number of simultaneous processing) is 2,700. In this way, when all the terminal devices 14 send voice signals at the same time, the server device 11 cannot forward all the voice signals without interruption, resulting in reduced sound quality and sound skipping.

[0032] Therefore, when the number of simultaneous receptions of the voice signal from the terminal device 14 reaches a given limit value (e.g., 2500), the server device 11 limits further transmission of the voice signal by the terminal device 14. Transmission restriction is performed by sending transmission restriction information to the terminal device 14. The transmission restriction information is information notifying each terminal device 14 not to transmit the voice signal. The transmission restriction information is added to the voice signal forwarded to the terminal device 14 and transmitted (restriction mark 101). During the period when the transmission restriction information is sent, the terminal device 14 performs transmission restriction on the terminal device 14 side, and does not transmit the voice signal even if the user operates the PTT switch 220.

[0033] Figure 21 is a diagram showing the structure of a voice packet 100. In this embodiment, an RTP packet is used as the voice packet 100. The voice signal is packetized by RTP every 20 ms. The RTP packet is composed of a header and a data body (payload). The header is composed of an IP header, a UDP header, and an RTP header. Figure 2 The header is shown in a simplified manner. The header includes a destination IP address and a transmission source address. In the case of a sound packet 100 sent from the terminal device 14 to the server device 11, the destination IP address is the IP address of the server device 11, and the transmission source address is the IP address of the terminal device 14. In addition, in the case of a sound packet 100 sent from the server device 11 to the terminal device 14, the destination IP address is the IP address of the terminal device 14, and the transmission source address is the IP address of the server device 11.

[0034] The data body of the voice packet 100 includes a digitized voice signal and communication control information. The communication control information includes a call type, a call ID, a transmission ID, and a restriction mark 101. The call type is information for identifying the type of communication (individual communication, group communication, and overall communication) for which the voice packet 100 is used to transmit the voice signal. The call ID is information for identifying the other party of communication. In the case of individual communication, the terminal number of the terminal device 14 of the other party of communication is used, and in the case of group communication, the group number of the calling group is used. The restriction mark 101 is a mark indicating the transmission restriction of the server device 11. The voice packet 100 sent when the server device 11 implements the transmission restriction is set with the restriction mark 101. That is, the set restriction mark 101 corresponds to the transmission restriction information of the present invention.

[0035] When the audio packet 100 received by the server device 11 from the terminal device 14 is an audio packet 100 for independent communication, the server device 11 re-edits the audio packet 100 as follows and transfers the audio packet 100 to the terminal device 14 of the communication partner.

[0036] The server device 11 performs the following operations.

[0037] The received audio signal (payload of the audio packet 100) is temporarily buffered.

[0038] A voice packet 100 is generated which has the buffered voice signal and communication control information as payload.

[0039] The IP address of the terminal device 14 of the communication partner is written in the audio packet 100 as the destination IP address.

[0040] The IP address of the server device 11 is written in the audio packet 100 as a transmission source address.

[0041] The restriction flag 101 of the audio packet 100 is set / reset according to whether the transmission restriction is implemented / not implemented at this time.

[0042] The re-edited audio packet 100 is transferred to the terminal device 14 of the communication partner.

[0043] When the audio packet 100 received by the server device 11 from the terminal device 14 is an audio packet 100 for group communication, the server device 11 performs mixed audio transfer on the received audio signal. Mixed audio transfer is constituted by the following processing.

[0044] The server device 11 performs the following operations.

[0045] The audio signal (payload of the audio packet 100 ) received from the terminal device 14 belonging to the group is buffered for 20 ms.

[0046] The buffered sound signals are mixed to generate sound signals for forwarding to each terminal device 14 belonging to the group. Mixing is performed for each terminal device 14 so as not to generate echoes. For a terminal device 14 that has not sent a sound signal within 20ms, all buffered sound signals are mixed, and for a terminal device 14 that has sent a sound signal within 20ms, sound signals other than the sound signal sent by the terminal device 14 are mixed.

[0047] A voice packet 100 having the generated voice signal and communication control information as payload is generated for each terminal device 14 belonging to the group.

[0048] The IP address of the terminal device 14 at the transmission destination is written in the audio packet 100 as the destination IP address.

[0049] The IP address of the server device 11 is written in the audio packet 100 as a transmission source address.

[0050] The restriction flag 101 of the audio packet 100 is set / reset according to whether the transmission restriction is implemented / not implemented at this time.

[0051] The audio packet 100 generated for each terminal device 14 is transmitted to the terminal device.

[0052] Figure 31 is a block diagram of the terminal device 14. As described above, from a functional aspect, the terminal device 14 is a wireless network device that transmits and receives the voice packet 100 via the wireless access point (AP) 13 of the wireless LAN 16. The control unit 20 is composed of a microprocessor and controls the operation of the terminal device 14. The control unit 20 has a storage unit 21. The storage unit 21 has a RAM 210 and a flash ROM 211. The RAM 210 is used as a working memory during operation. The flash ROM 211 is used to store information such as network information in a non-volatile manner. A transmission restriction flag 2101 is set in the RAM 210.

[0053] The control unit 20 is connected to the operation unit 22, the display unit 23, the audio circuit 24, and the wireless LAN communication unit 25. The operation unit 22 includes a key switch such as a PTT switch 220, receives a user's operation, and inputs the operation signal to the control unit 20. The display unit 23 includes a liquid crystal display. The liquid crystal display displays the terminal number / group number of the communication partner selected by the user's operation, the terminal number / group number of the communication partner of the incoming call, and the like.

[0054] The audio circuit 24 has a microphone 240 and a speaker 241. The control unit 20 decodes the received voice packet 100 and inputs it to the audio circuit 24. The audio circuit converts the decoded audio signal into an analog signal and outputs it from the speaker 241. In addition, the audio circuit 24 converts the audio signal input from the microphone 240 into a digital signal and inputs it to the control unit 20. The control unit 20 converts the digital audio signal into a voice packet and inputs it to the wireless LAN communication unit 25. The wireless LAN communication unit 25 has a circuit for wireless communication in accordance with the communication method of IEEE802.11. The wireless LAN communication unit 25 transmits the packet input from the control unit 20 to the wireless access point 13. With the above functions, when the user speaks to the microphone 240 while pressing the PTT switch 220, the voice signal is edited into the voice packet 100 and transmitted to the server device 11. In addition, the wireless LAN communication unit 25 inputs the packet received from the server device 11 via the wireless access point 13 to the control unit 20.

[0055] The terminal device 14 has a PTT switch 220 and a VOX circuit 242 together. The VOX circuit 242 is a circuit that determines whether the user's call voice (sound signal) is input based on the input level of the microphone 240 and its duration. When it is determined that the call voice is input, the VOX circuit 242 switches the terminal device 14 to the same transmission state as when the PTT switch 220 is turned on. The terminal device 14 switches the transmission on / off based on and uses one or both of the turning on of the PTT switch 220 and the VOX circuit 242 through mode setting. The turning on of the PTT switch 220 in the description of this embodiment includes the switching to the transmission state performed by the VOX circuit 242.

[0056] Figure 4 1 is a block diagram of a server device 11. The server device 11 includes a control unit 30, a storage unit 31, and a network communication unit 32. The storage unit 31 is composed of, for example, a hard disk, a RAM, etc. The network communication unit 32 controls communication with the wired network 15. The control unit 30 mixes and forwards the audio signal sent from the terminal device 14. The storage unit 31 is set with Figure 5 The terminal table 311 and Figure 6 The group table 312 shown, Figure 7 The session table 313 shown, Figure 8 The illustrated transmitting terminal table 314, transmitting terminal number register 315, and restriction flag 316. The value stored in the transmitting terminal number register 315 corresponds to the "simultaneous reception number" of the present invention.

[0057] Figure 5 1 is a diagram showing a terminal table 311 provided in the storage unit 31 of the server device 11. The terminal table 311 registers the terminal devices 14 used in the voice communication system. The maximum number of terminal devices 14 that can be registered in the terminal table 311 (maximum number of accommodation) is 3,000. Each terminal device 14 is identified by a terminal number that is uniquely assigned. In the terminal table 311, an activity flag, an IP address, and an IP address of a connected wireless access point 13 of the terminal device 14 are stored for each terminal number. The activity flag is a flag indicating that the power of the terminal device 14 is turned on and communication is possible.

[0058] Figure 6 3 is a diagram showing a group table 312. The group table 312 registers groups to which a plurality of terminal devices 14 belong. Each group is identified by a uniquely assigned group number. The group table 312 stores, for each group, a group number and terminal numbers of the terminal devices 14 belonging to the group.

[0059] Figure 71 is a diagram showing a session table (mixing table) 313. The session table 313 is a table used by the server device 11 to manage communication sessions. A communication session is a communication between multiple terminal devices 14 relayed by the server device 11. The session table 313 has multiple rows, and each row stores information about a communication session. When the server device 11 receives a sound signal (sound packet 100) from the terminal device 14, it refers to the session table 313 to determine which communication session the sound signal belongs to.

[0060] When the server device 11 receives the first audio packet 100 (hereinafter referred to as the call audio packet 100 ) for calling the terminal device 14 of the communication partner from the terminal device 14 , the communication session based on the call audio packet 100 is registered in the session table 313 .

[0061] In the session table 313, items of a session number, a calling terminal number, a participating terminal number, and a holding timer (TS) are provided for each communication session. The session number is a number for identifying the communication session. The calling terminal number is the terminal number of the terminal device 14 that has sent the call voice packet 100 of the communication session. The participating terminal number is the terminal number of the terminal device 14 that is currently participating in the communication session. When a voice signal is sent from the terminal device 14 that is currently participating in the communication session, the server device 11 forwards the voice signal to other terminal devices 14 registered in the participating terminal number.

[0062] The holding time timer TS is a timer for counting the non-communication time of the communication session. The so-called non-communication refers to a state where no voice packet 100 is sent from any terminal device 14 participating in the communication session. The server device 11 maintains the communication session for 30 seconds even in the non-communication state. The server device 11 Fig.11 In the session table management process, the communication session whose non-communication time becomes more than 30 seconds is deleted from the session table 313.

[0063] Figure 8 314, a transmission terminal number register 315, and a restriction flag 316. The transmission terminal table 314 registers the terminal numbers of the terminal devices 14 that have transmitted the audio packet 100 to the server device 11 within the last 20 ms. Furthermore, the transmission terminal table 314 stores transmission continuation flags corresponding to the registered terminal numbers. Fig. 9 as well as Fig.10 The details are described in the description of the flowchart.

[0064] Fig. 9The flowchart shows the processing operation when the server device 11 receives a sound signal (sound packet 100) from the terminal device 14. When the server device 11 receives the sound packet 100, it performs the following processing (S10). The server device 11 infers the terminal number of the terminal device 14 that has transmitted the received sound packet 100, and determines whether the terminal number is registered in the transmission terminal table 314 (S11). When the terminal number is not registered in the transmission terminal table 314 (S11: No), the server device 11 registers the terminal number of the terminal device 14 in the transmission terminal table 314 (S12), and adds 1 to the transmission terminal number register 315 (S13). When registering the terminal number, the server device 11 sets the corresponding transmission continuation flag. When the terminal number is already registered in the transmission terminal table 314 (S11: Yes), the server device 11 sets the transmission continuation flag corresponding to the terminal device 14 (S14).

[0065] In S15, the server device 11 refers to the transmission terminal number register 315 to determine whether the number of transmission terminals has reached the number of transmission terminals (limit value) for starting transmission restriction, that is, 2500. When the number of transmission terminals has reached 2500 (S15: Yes), the server device 11 sets the restriction flag 316 (S16). When the number of transmission terminals has not reached the limit value of 2500 (S15: No), the server device 11 resets the restriction flag 316 (S17).

[0066] In S18, the server device 11 determines whether the communication session in which the terminal device 14 of the sender of the received voice packet 100 participates is registered in the session table 313. In the case where the communication session in which the terminal device 14 of the sender of the voice packet 100 participates is not registered in the session table 313 (S18: No), the server device 11 newly registers the communication session with the terminal device 14 and the terminal device 14 or group of the communication partner as participating terminals in the session table 313 (S19). In the case where the communication session in which the terminal device 14 of the sender of the voice packet 100 participates is already registered in the session table 313 (S18: Yes), the server device 11 resets the holding time timer TS of the communication session to 30 seconds (S20).

[0067] After that, the server device 11 forwards the received sound signal. The server device 11 determines whether the restriction mark 316 is set (S21). In the case where the restriction mark 316 is set (S21: Yes), the server device 11 sets the restriction mark 101 on the sound packet 100 and forwards it to the terminal device 14 of the communication partner (S22). In the case where the restriction mark 316 is not set (S21: No), the server device 11 resets the restriction mark 101 on the sound packet 100 and forwards it to the terminal device 14 of the communication partner (S23).

[0068] In the case of individual communication, the server device 11 forwards the sound signal received in S10 to the communicating party's terminal device 14. In the case of group communication, the server device 11 not only receives the sound signal in S10 this time, but also buffers the sound signal received from other terminal devices 14 in the group for 20ms, mixes the buffered sound signal and forwards it.

[0069] Fig.10 1 is a flowchart showing the management process of the sending terminal table 314. This process is repeatedly performed regularly every 20 milliseconds in accordance with the sending interval of the sound packet 100. The server device 11 first specifies the first row of the sending terminal table 314 (S31). The server device 11 determines whether the sending continuation flag of the specified row is set (S32). In the case where the sending continuation flag is reset (S32: No), the server device 11 considers that the terminal device 14 recorded in the row has ended the sending of the sound signal and deletes the registration of the row (S33). The server device 11 subtracts 1 from the sending terminal number register 315 (S34). After the subtraction operation, the number of sending terminals is determined (S35). In the case where the number of sending terminals is less than 2500, which is the limit value (S35: Yes), the server device 11 resets the limit flag 316 (S36).

[0070] In S32, if the transmission continuation flag is set (S32: Yes), the server device 11 considers that the terminal device 14 recorded in the row continues to transmit the sound signal and skips the processing of S33-S36. The server device 11 performs the above processing in sequence until it reaches the last row of the transmission terminal table 314 (S37, S38). By performing the above processing to the last row of the transmission terminal table 314, the terminal device 14 that no longer transmits the sound packet 100 is deleted from the transmission terminal table 314.

[0071] The server device 11 resets the transmission continuation flags corresponding to all the terminal devices 14 registered in the transmission terminal table 314 (S39), and ends the processing. During the next 20 ms, when a voice packet 100 is transmitted from a terminal device 14 registered in the transmission terminal table 314, the server device 11 sets the transmission continuation flag corresponding to the terminal device 14 (refer to Fig. 9 By setting this flag, it is recorded that the terminal device 14 continues to send the voice packet 100. After 20ms, the sending terminal table management process is executed again ( Fig.10 ), the server device 11 regards that the terminal device 14 with the sending continuation mark is continuing to send the sound packet 100, thereby leaving the registration, and the terminal device 14 with the sending continuation mark reset ends the sending of the sound packet 100, thereby deleting the registration.

[0072] Fig.11 1 is a flowchart showing the management process of the session table 313. This process is repeatedly performed regularly every 20 milliseconds in accordance with the transmission interval of the voice packet 100. The server device 11 first specifies the communication session in the first row of the session table 313 (S41). The server device 11 subtracts 1 count (corresponding to 20 milliseconds) from the hold time timer TS of the specified communication session (S42), and determines whether the hold time timer TS becomes 0 by this subtraction (S43). When the hold time timer TS is 0 (S43: Yes), the server device 11 regards the communication session as ended and deletes the communication session in this row (S44). The server device 11 deletes the ended communication session from the session table 313 by performing the above process in sequence until it becomes the last row of the session table 313 (S45, S46).

[0073] Fig.12 1 is a flowchart showing the receiving process of the terminal device 14. This process is repeatedly performed regularly every 20 milliseconds in accordance with the transmission interval of the voice packet 100. The control unit 20 of the terminal device 14 first determines whether the voice packet 100 is received from the server device 11 during the 20 ms period (S51). In the case where the voice packet 100 is not received (S51: No), the control unit 20 resets the transmission restriction flag 2101 (S52) and ends the process. Since the transmission restriction flag 2101 is reset, the terminal device 14 transmits the voice signal when the PTT switch 220 is pressed.

[0074] When the voice packet 100 is received (S51: Yes), the control unit 20 extracts the voice signal from the received voice packet 100 (S53), and outputs the voice signal to the audio circuit 24 (S54). The control unit 20 determines whether the restriction mark 101 of the received voice packet 100 is set (S55). When the restriction mark 101 is set (S55: Yes), the control unit 20 sets the transmission restriction mark 2101 (S56). Since the transmission restriction mark 2101 is set, the terminal device 14 no longer transmits the voice signal even if the PTT switch 220 is pressed. When the restriction mark 101 of the voice packet 100 is not set (S55: No), the control unit 20 resets the transmission restriction mark 2101 (S52). After the processing of S52 or S55, the control unit 20 ends the processing.

[0075] Fig.13 1 is a flowchart showing the operation when the PTT switch 220 is pressed in the terminal device 14. When the PTT switch 220 is pressed (S60), the control unit 20 determines whether the transmission restriction flag 2101 is set (S61). When the transmission restriction flag 2101 is set (S61: Yes), the control unit 20 outputs a restriction sound such as "Pu Pu Pu" from the speaker 241 (S62) and does not transmit the voice signal.

[0076] When the transmission restriction flag 2101 is not set (S61: No), the control unit 20 transmits the audio signal input from the microphone 240 to the server device 11 (S63). The audio signal is packetized by the control unit 20 every 20 ms, and the wireless LAN communication unit 25 transmits the audio packet 100 to the server device 11. The server device 11 continues to transmit the audio signal until the PTT switch 220 is turned off (S64). While the PTT switch 220 is on, the audio signal is continued to be transmitted even if the transmission restriction flag 2101 is set in the process of S56. When the PTT switch 220 is turned off (S64: Yes), the control unit 20 ends the transmission of the audio signal.

[0077] Since the terminal device 14 communicates in full duplex, in the case of group communication (especially in the case of group communication with many participants), it almost always receives the audio signal from the server device 11. Therefore, when the server device 11 starts the transmission restriction and sends the audio packet 100 with the restriction mark 101, the terminal device 14 enters the transmission restriction state where it cannot send from its own device.

[0078] On the other hand, the terminal device 14 not participating in the group communication and not communicating does not set its transmission restriction flag 2101 because it does not receive the voice packet 100 from the server device 11. Therefore, the terminal device 14 not communicating can make a new call, that is, start a communication session.

[0079] For the terminal device 14 of the communication partner called by the new call, a voice packet 100 with a restriction mark 101 is sent from the server device 11. Therefore, the terminal device 14 cannot immediately respond to the call. However, when the called terminal device 14 stops sending sound, since the voice packet 100 is no longer sent to the terminal device 14 of the communication partner, the sending restriction mark 2101 is immediately reset (in 20ms). As a result, the terminal device 14 of the communication partner can respond to the terminal device 14 that has made the call. That is, a simplex communication session such as waiting for the other party's sending to complete and then starting the sending of this device will also be ensured after the server device 11 starts sending restrictions. The limit value (2500) of the communication restriction is set to a value lower than the maximum number of simultaneous processing (2700) in order to ensure the simplex communication. Simplex communication can also be group communication.

[0080] In this embodiment, a so-called wireless LAN transceiver system that communicates via the network 17 including the wireless LAN 16 is described, but the present invention can also be applied to a voice communication system using an LTE network. In this case, it is not necessary Figure 5 The terminal table 311 shown has a column for the connection destination AP.

[0081] In addition to the terminal devices 14 connected via the network 17, the server device 11 can also relay the voice communications of the terminal devices 14 at other locations connected via VPN and the telephones connected via the RoIP gateway. When the communications of these devices are relayed, when there is a call from these devices or a voice signal is sent, these devices can also be counted as the number of sending terminals.

[0082] In this embodiment, the maximum number of server devices 11 to be accommodated is set to 3000, the maximum number of simultaneous processing is set to 2700, and the limit value is set to 2500, but the respective values ​​are not limited thereto. In this embodiment, when the number of sending terminals reaches the limit value, the limit mark 316 is set to be effective, but the limit mark 316 may also be set to be effective when the number of sending terminals exceeds the limit value. In this embodiment, the size of the packetization of the sound signal and the sending interval of the sound packet are set to 20ms, but these values ​​are not limited to 20ms. In addition, the numerical values ​​described in this embodiment can be freely set within the scope of the subject matter.

[0083] In addition, Figure 9-13 The processing steps illustrated in the flowcharts may be different from each other within the range not hindering the processing.

[0084] The voice communication system and the voice communication method described in the column of "Means for Solving the Problem" can be added or modified in the following aspects.

[0085] The terminal device performs full-duplex communication, and while transmitting a voice signal to the server device, it also receives a voice signal transmitted from the server device in parallel.

[0086] The server device and the terminal device divide the audio signal at given time intervals (e.g., 20 ms) and sequentially transmit the audio signal as audio packets. The server device counts the number of simultaneous receptions at given time intervals, and when the number of simultaneous receptions reaches a given limit value, the audio packet is attached with transmission restriction information and transmitted. When the terminal device receives the audio packet with the transmission restriction information, it restricts the transmission for a given time.

[0087] Even if the terminal device receives a voice signal from another terminal device to which transmission restriction information is added during transmission of the voice signal, the terminal device continues to transmit the voice signal until the transmission is completed.

[0088] When the number of simultaneous receptions in the server device reaches a given limit value, the first terminal device and the second terminal device (group) may perform alternate communication (simplex communication). Alternate communication refers to a communication method in which the second terminal device starts sending a sound signal after the first terminal device finishes sending a sound signal, and the first terminal device starts sending a sound signal after the second terminal device finishes sending a sound signal.

[0089] The voice communication program described in the column of "Means for Solving the Problem" can be added or modified in the following ways.

[0090] The first unit sequentially receives audio packets including an audio signal divided at every given time, and the second unit counts the number of simultaneous receptions at every given time.

[0091] -Description of Reference Numerals-

[0092] 11 Server Device

[0093] 13 Wireless Access Point

[0094] 14 Terminal Devices

[0095] 16 Wireless LAN

[0096] 17 Network

[0097] 100 sound groups

[0098] 315 Sending terminal number register

[0099] 101, 316 Restriction Mark

[0100] 2101 Send restriction flag.

Claims

1. A voice communication system comprising a server device and a plurality of terminal devices connected to each other via a network, The voice communication system is characterized in that The first terminal device, which is a sender among the plurality of terminal devices, transmits a voice signal and identification information of the second terminal device, which is a responder among the plurality of terminal devices, to the server device according to a transmission operation of a user. The server device forwards the audio signal sent from the first terminal device to the second terminal device, The server device always counts the number of simultaneous receptions of the audio signal. When the number of simultaneous receptions reaches a given limit value, adding transmission restriction information to the received audio signal and forwarding it to the second terminal device, The second terminal device performs transmission restriction so as not to transmit the audio signal even if there is a transmission operation by the user while receiving the audio signal to which the transmission restriction information is added, The number of simultaneous receptions is the number of the terminal devices that transmit the audio signal to the server device.

2. The voice communication system according to claim 1, in, The terminal device performs full-duplex communication and, while transmitting a voice signal to the server device, simultaneously receives a voice signal transmitted from the server device.

3. The voice communication system according to claim 2, in, The server device and the terminal device divide the audio signal into audio packets at given intervals and transmit them sequentially. The server device counts the number of simultaneous receptions at intervals of the given time, and when the number of simultaneous receptions reaches a given limit value, adds transmission restriction information to the voice packet and transmits the voice packet. The terminal device, when receiving the audio packet to which the transmission restriction information is added, imposes the transmission restriction for the given time.

4. The voice communication system according to any one of claims 1 to 3, in, Even if the terminal device receives a voice signal from another terminal device to which the transmission restriction information is added during transmission of the voice signal, the terminal device continues to transmit the voice signal until the transmission is completed.

5. A voice communication method, comprising a plurality of terminal devices, namely a first terminal device as a sender and a second terminal device as a responder, communicating with each other via a server device, wherein the server device is connected via a network, The voice communication method is characterized in that The first terminal device transmits a voice signal and identification information of the second terminal device, which is a communication partner, to the server device according to a transmission operation of the user. The server device forwards the audio signal sent from the first terminal device to the second terminal device, The server device always counts the number of simultaneous receptions of the sound signal, and when the number of simultaneous receptions reaches a given limit value, adds transmission restriction information to the received sound signal and forwards it to the second terminal device. The second terminal device performs transmission restriction so as not to transmit the audio signal even if there is a transmission operation by the user while receiving the audio signal to which the transmission restriction information is added, The number of simultaneous receptions is the number of the terminal devices that transmit the audio signal to the server device.

6. The voice communication method according to claim 5, in, The terminal device performs full-duplex communication and, while transmitting a voice signal to the server device, simultaneously receives a voice signal transmitted from the server device.

7. The voice communication method according to claim 6, in, The server device and the terminal device divide the audio signal into audio packets at given intervals and transmit them sequentially. The server device counts the number of simultaneous receptions at intervals of the given time, and when the number of simultaneous receptions reaches a given limit value, adds transmission restriction information to the voice packet and transmits the voice packet. The terminal device, when receiving the audio packet to which the transmission restriction information is added, imposes the transmission restriction for the given time.

8. The voice communication method according to any one of claims 5 to 7, in, Even if the terminal device receives a voice signal from another terminal device to which the transmission restriction information is added during transmission of the voice signal, the terminal device continues to transmit the voice signal until the transmission is completed.

9. The voice communication method according to any one of claims 5 to 8, in, When the number of simultaneous receptions in the server device reaches the given limit value, the first terminal device and the second terminal device communicate alternately, that is, after the first terminal device finishes sending the sound signal, the second terminal device starts sending the sound signal, and after the second terminal device finishes sending the sound signal, the first terminal device starts sending the sound signal.

10. A recording medium recording a voice communication program, the voice communication program causing a control unit of a server device that communicates with a plurality of terminal devices including a first terminal device as a sender and a second terminal device as a responder via a network to function as a unit that: A first unit that receives a sound signal sent from the first terminal device; A second unit that always counts the number of simultaneous receptions of the sound signal; and a third unit for forwarding the received sound signal to the second terminal device, and for adding transmission restriction information to the received sound signal and forwarding it to the second terminal device when the number of simultaneous receptions reaches a given limit value, The number of simultaneous receptions is the number of the terminal devices that transmit the audio signal to the server device.

11. The recording medium according to claim 10, in, The first unit sequentially receives voice packets including voice signals divided at given intervals. The second unit counts the number of simultaneous receptions at every given time.

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