HK1223466B - Relay device, voice communication system, recording medium, and method for relaying voice signal - Google Patents

Description

Relay device, voice communication system, recording medium, and voice signal relay method

Technical Field

The present invention relates to a voice communication system utilizing a network such as a wireless LAN.

Background Art

Conventionally, so-called wireless communication devices, which modulate a high-frequency carrier wave (a continuous-time signal) with an analog or digital signal and transmit it, have been the mainstream for wireless voice communication. While one-to-one communication is a basic function of wireless communication devices, some have also been proposed, including group communication capabilities that allow multiple wireless communication devices to communicate simultaneously (see Non-Patent Document 1).

Conventional group communication using wireless communication devices is achieved by configuring each wireless communication device to belong to a specific group, and then having the wireless communication device determine whether to respond to group calls. Specifically, when a group communication call comes in from another wireless communication device, it determines whether the call is addressed to the group to which the device belongs. If so, the device responds to the call. If there are multiple wireless communication devices (three or more) assigned to the same group, group communication is enabled between these devices.

Prior art literature

Non-patent literature

Non-Patent Document 1: JVC Kenwood Co., Ltd., Business Wireless Network TCP-U90F <URL: http://www2jvckenwood.com/business/tcp_u90f/>

Summary of the Invention

Problems to be solved by the invention

While group communication can be performed using three or more wireless communication devices in Non-Patent Document 1, the communication format is half-duplex. Therefore, even with group communication, only one device can transmit audio signals (can speak). If two or more devices transmit audio signals simultaneously, the transmitting wireless communication device cannot receive signals from other wireless communication devices. Furthermore, because multiple transmissions are jammed, the receiving wireless communication device cannot hear the audio.

In group communication, where the group to which each wireless communication device is assigned is stored, it is impossible to comprehensively manage which wireless communication devices belong to which group. Furthermore, unless the group assigned to each wireless communication device is changed, it is impossible to change the wireless communication device belonging to a group, making it impossible to flexibly change the group settings according to real-time conditions.

An object of the present invention is to provide a voice communication system in which a relay device and a terminal device as a communication device are connected via a communication network, and the relay device manages a group of terminal devices, thereby enabling group communication with a high degree of freedom.

Means for solving problems

The relay device of the present invention comprises: a network communication unit for communicating with a terminal device via a network, a control unit for controlling communication with the terminal device, and a storage unit having a session table set therein. The network communication unit receives a voice signal to which information specifying the terminal device of the communication partner is attached from the terminal device. When the control unit receives the initial voice signal (e.g., a call voice data packet described later) from the terminal device, it registers the terminal device that sent the voice signal and the terminal device specified by the designation information attached to the voice signal in the session table as a communication session of participating terminals. In order to establish a communication session, it is sufficient to start sending the voice signal, and no prior process such as the SIP process is required. Then, the control unit forwards the voice signal received from the participating terminal including the initial voice signal to each participating terminal. When voice signals are received from two or more participating terminals at the same time, the control unit mixes the voice signals and sends the mixed voice signal to the participating terminals.

The program of the present invention causes a computer including a network communication unit for communicating with a terminal device via a network and a relay device having a storage unit configured with a session table to function as the first, second, and third units. The first unit, upon receiving an initial voice signal from a terminal device to which information specifying the communication partner's terminal device is attached, registers the terminal device that transmitted the voice signal and the terminal device specified by the designation information attached to the voice signal as participating terminals in the communication session in the session table. The second unit forwards the voice signal (including the initial voice signal) received from the participating terminal to each participating terminal. The third unit, upon receiving voice signals simultaneously from two or more participating terminals, mixes the voice signals and transmits the mixed voice signal to the participating terminals.

The present invention's audio signal relay method utilizes a relay device equipped with a network communication unit for communicating with terminal devices via a network and a storage unit configured with a session table to relay audio signals. In a first step, upon receiving an initial audio signal from a terminal device, to which information specifying the communicating party's terminal device is attached, the relay device registers the terminal device that transmitted the audio signal and the terminal device specified by the designation information attached to the audio signal as participating terminals in the communication session in the session table. In a second step, the relay device forwards the audio signal received from the participating terminal, including the initial audio signal, to each participating terminal. In a third step, upon receiving audio signals simultaneously from two or more participating terminals, the relay device mixes the audio signals and transmits the mixed audio signal to the participating terminals.

In the third step, the control unit, the third unit, and the relay device may transmit a signal obtained by mixing the received audio signal other than the audio signal transmitted from the terminal device to the terminal device that transmitted the audio signal.

The control unit, the first unit, and the relay device may delete the communication session from the session table in the first step and in the first step if no audio signal is received from any participating terminal and a predetermined time period has elapsed.

The control unit, the first unit, and the relay device can, in the first step, register the terminal device that sent the sound signal and the terminal devices belonging to the original group as participating terminals in the communication session in the session table when the designated information attached to the initial sound signal received from the terminal device is information designating the original group.

The control unit, the first unit, and the relay device can, in the first step, register in the session table a new communication session in which the terminal device that sent the sound signal and the terminal device specified by the designation information are participating terminals upon receiving a sound signal to which designation information is attached that specifies at least one terminal device that is not included in the participating terminals of the communication session previously registered in the session table.

The control unit, the first unit, and the relay device can, in the first step, delete the terminal device that will become the participating terminal of the communication session between the two parties from the (participating terminals of the) previously registered communication session when the participating terminals of the newly registered communication session include the participating terminals of the previously registered communication session.

The voice communication system of the present invention includes: a terminal device equipped with a microphone, a voice output unit, and a terminal network communication unit; and a relay device equipped with a network communication unit, a control unit, and a storage unit. The terminal network communication unit of the terminal device and the network communication unit of the relay device transmit and receive voice signals via a network. The terminal device appends information specifying the terminal device of the communication partner to the voice signal input from the microphone and transmits it to the relay device, and then reproduces the voice signal received from the relay device. The relay device's storage unit includes a session table. The network communication unit of the relay device receives the voice signal with the specified information appended from the terminal device.

Upon receiving the initial audio signal (call audio packet) from a terminal device, the relay device's control unit registers the terminal device that transmitted the audio signal, along with the terminal device specified by the designation information attached to the audio signal, as a participating terminal's communication session in the session table. Establishing a communication session requires only the initiation of audio signal transmission, eliminating the need for prior steps such as those in the SIP process. The control unit then forwards the audio signals received from the participating terminal, including the initial audio signal, to each participating terminal. If audio signals are received simultaneously from two or more participating terminals, the control unit mixes these audio signals and transmits the mixed audio signal to the participating terminals.

The terminal device may further include a push-to-talk (PTT) circuit, and the terminal network communication unit transmits the audio signal input from the microphone to the relay device while the PTT switch is on, and receives the audio signal transmitted from the relay device regardless of whether the PTT circuit is on or off.

The network may have a plurality of access points of a wireless local area network (LAN), and the terminal network communication unit of the terminal device may be connected to the network via any of the access points.

Effects of the Invention

According to the present invention, a relay device and a terminal device are connected via a network, and the relay device relays communication between the terminal devices, thereby enabling group communication with a high degree of freedom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a block diagram of a voice communication system according to an embodiment of the present invention.

FIG2 is a block diagram of a transceiver serving as a terminal device.

FIG3 is a diagram showing an example of the structure of a voice data packet.

FIG4 is a block diagram of a server device.

FIG. 5A is a diagram showing a terminal table set in the server device.

FIG5B is a diagram showing a group table set in the server device.

FIG5C is a diagram showing a hybrid table set in the server device.

FIG6 is a flowchart showing the operation of the transceiver.

FIG7A is a flowchart showing the operation of the server device.

FIG7B is a flowchart showing the operation of the server device.

DETAILED DESCRIPTION

The voice communication system of the present invention will be described with reference to the accompanying drawings. FIG1 is a block diagram of a voice communication system as an embodiment of the present invention. In this voice communication system, a plurality of terminal devices 14 communicate with each other using a wireless LAN 16 such as Wi-Fi. The terminal device 14 is in a shape similar to a portable transceiver for wireless communication and has a PTT (push-to-talk) switch 220 as shown in FIG2 . Functionally, the terminal device 14 is a wireless network device that sends and receives voice data packets via a wireless access point (AP) 13. The server device 11, which serves as a relay device, relays the mutual communication of the plurality of terminal devices 14 via a wired network 15 and a wireless LAN (local area network) 16. In addition, hereinafter, the wired network 15 and the wireless LAN 16 are collectively referred to as a network 17.

When the terminal device 14 is activated, it connects to the network 17. When the terminal device 14 connects to the network 17, the server device 11 transmits configuration data to the terminal device 14, enabling communication with the terminal device 14. The configuration data transmitted by the server device 11 includes, for example, the group number with which the terminal device 14 can communicate, an update program, and the like. Furthermore, various configuration data is transmitted to the terminal device 14 at appropriate times thereafter. Such appropriate times include, for example, when the wireless access point 13 to which the terminal device 14 is connected is switched at regular intervals.

As the wired network 15, an Ethernet (registered trademark) LAN, the Internet, or the like can be used. When the Internet is included in the wired network 15, secure communication can be achieved by using a VPN (Virtual Private Network). Furthermore, as the wireless LAN 16, a communication method compliant with IEEE802.11, such as Wi-Fi, can be used. The terminal device 14 and the wireless access point 13 communicate using the communication method of the wireless LAN 16.

There are multiple wireless access points 13. Each wireless access point 13 is installed on a different floor or room of a building, for example. Therefore, it is possible to estimate which floor or room a terminal device 14 is located based on which wireless access point 13 the terminal device 14 belongs to.

The management device 12 is connected to the wired network 15. The management device 12 is comprised of, for example, a personal computer with a management program installed. Based on an administrator's operation, the management device 12 accesses the server device 11 and sets the tables shown in Figures 5A and 5B on the server device 11. Furthermore, the management device 12 functions as a terminal device and can communicate with other terminal devices 14.

FIG2 is a block diagram of the terminal device 14. As described above, functionally, the terminal device 14 is a wireless network device that transmits and receives voice data packets via the wireless access point (AP) 13 of the wireless LAN. The control unit 20 controls the operation of the terminal device 14 and is composed of a microprocessor. The control unit 20 has a storage unit 21 that stores various data. The setting data downloaded from the server device 11 is stored in the storage unit 21. The control unit 20 is connected to an operation unit 22, a display unit 23, an audio circuit 24, and a wireless LAN communication unit 25. The operation unit 22 includes a push button switch such as a PTT switch 220, and after receiving the user's operation, the operation signal is input to the control unit 20. The display unit 23 includes a liquid crystal display. The liquid crystal display displays the identification number of the communication partner selected by the user's operation, the identification number of the incoming caller, etc.

The audio circuit 24 includes a microphone 240 and a speaker 241. The control unit 20 decodes received audio data packets and inputs them to the audio circuit 24. The audio circuit converts the decoded audio signal into an analog signal and outputs it from the speaker 241. Furthermore, 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 audio data packets and inputs them to the wireless LAN communication unit 25. The wireless LAN communication unit 25 includes circuitry for wireless communication using a communication method compliant with IEEE 802.11. The wireless LAN communication unit 25 transmits data packets input from the control unit 20 to the wireless access point 13 and inputs data packets received from the wireless access point 13 to the control unit 20.

When the user speaks into microphone 240 while pressing PTT switch 220, terminal device 14 compiles the sound signal into a sound data packet and sends it to server device 11. The sound data packet is structured as shown in Figure 3. The header of the sound data packet contains the destination IP address (destination address) and the source address (sender address). The data body contains the communication partner identification number and the source terminal number along with the digitized sound signal. The communication partner identification number is information that identifies the communication partner (target device). In the case of individual communication, the terminal number of the terminal device 14 is used, and in the case of group communication, the group number of the group is used. Although the destination of the sound data packet sent from terminal device 14 is server device 11, the final destination of the sound signal is the communication partner's terminal device 14. Upon receiving the sound data packet, server device 11 extracts the data body from the sound data packet and forwards the sound signal to the communication partner's terminal device 14. If the communication partner's identification number is the identification number of a group, that is, in the case of group communication, the sound signal is forwarded to multiple terminal devices 14 belonging to the group.

When forwarding the sound signal, a new sound data packet is created with the IP address of the forwarding destination terminal device 14 as the destination address and the IP address of the server 11 as the source address. In the case of individual communication, the communication party identification number and the source terminal number contained in the data body of the new data packet are the same as the communication party identification number and the source terminal number contained in the data body of the sound data packet received by the server device 11. In the case of group communication, the communication party identification number contained in the data body of the new data packet is the same as the communication party identification number contained in the data body of the sound data packet received by the server device 11. In addition, the source terminal number can be cleared or the same source terminal number as the source terminal number contained in the data body of the sound data packet received by the server device 11 can be added.

To summarize the above process, when the PTT switch 220 is turned on, the terminal device 14 does not perform the communication establishment process such as the SIP process, but instead sends a voice data packet to the server device 11, which is a voice signal input from the microphone 240 and has the identification number of the communication partner appended to it. The server device 11 forwards this voice signal to the communication partner identified by the identification number. In this way, in this voice communication system, communication begins by sending a voice data packet (RTP data packet), so the user can start communication almost simultaneously with turning on the PTT switch 220, and can communicate with the same user experience as a conventional wireless communication transceiver. To achieve this user experience, the server device 11 manages the IP address, group, etc. of each terminal device 14, and forwards the voice signal.

Terminal device 14 not only has a PTT switch 220 but also a VOX circuit. The VOX circuit determines whether a call (voice signal) is being input based on the input level and duration of microphone 240, and switches the device to a transmitting mode (PTT switch on) if a call is detected. Terminal device 14 can use the VOX circuit in place of or in addition to the PTT switch 220 to switch transmission on and off. Conventional wireless communication transceivers are simplex and cannot receive wireless signals while in the transmitting mode. On the other hand, terminal device 14 transmits and receives voice signals using voice packet communication via wireless LAN 16, enabling simultaneous transmission and reception of voice packets. This functionality enables full-duplex communication, allowing simultaneous transmission and reception of voice signals. However, the terminal device 14, using the PTT switch 220 or VOX function, only edits and transmits voice packets when a call is being input, preventing the continuous transmission of silent voice packets even during full-duplex communication.

The server device 11 forwards the audio signal contained in the audio data packet received from the terminal device 14 via the network 17 to the communicating terminal device 14 via the network 17. In group communication, the audio signal is forwarded to multiple terminal devices 14 belonging to the group. In group communication, multiple users may speak simultaneously, and audio signals may be transmitted simultaneously from multiple terminal devices 14. In such cases, the server device 11 mixes these multiple audio signals, compiles a new audio signal, and forwards this new audio signal as an audio data packet to each terminal device 14. Furthermore, the mixing performed by the server device 11 is configured to be performed for each forwarding terminal device 14, and the audio signal transmitted by the server device 11 is not included in the returned mixed audio. In other words, the server device 11 forwards a mixed signal of all received audio signals to terminal devices 14 that are not transmitting audio signals. For terminal devices 14 that are transmitting audio signals, the server device 11 excludes the audio signal transmitted by that terminal device 14 and forwards a mixed signal of all other audio signals. This prevents the audio signal transmitted by the server device 11 from echoing back to the terminal devices 14.

When group communication is performed, the configuration of the terminal devices 14 belonging to the group is not fixed, but is flexibly increased or decreased according to the communication status of each terminal device 14 at that time. Details will be described with reference to the table in FIG5 .

Figure 4 is a block diagram of the 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, which is composed of, for example, a hard disk or RAM, stores the various tables shown in Figure 5 and configuration data for each terminal device 14. The control unit 30 performs configuration of the terminal devices 14, mixing of audio signals, and other operations. The network communication unit 32 controls communication with the wired network 15.

5A , 5B, and 5C are diagrams showing tables provided in the storage unit 31 of the server device 11 .

FIG5A is a diagram showing a terminal table 301. The terminal table 301 is a table used by the server device 11 to manage the terminal devices 14. Each terminal device 14 is identified by a uniquely assigned identification number (terminal number). In the terminal table 301, an activation flag and a storage address for setting data are stored for each terminal number. The activation flag is a flag indicating that the terminal device 14 is connected to the network 17 and has accessed the server device 11, and has accepted registration and download of various data from the server device 11. In other words, it is a flag indicating that registration is complete and communication is possible. The activation flag is set by the server device 11 when registration of the terminal device 14 is complete. Setting data includes, for example, program update data (firmware), a phone book that records the group to which the terminal device belongs, and other groups with which communication is permitted.

When the terminal device 14 is connected to the network 17, the server device 11 communicates with the terminal device 14 to register the terminal device 14. Furthermore, at an appropriate time thereafter, the server device 11 communicates with the terminal device 14 to update the registration of the terminal device 14. The appropriate time thereafter is, for example, when the wireless access point 13 to which the terminal device is connected is switched at regular intervals.

When selecting a communication partner, the user operates the terminal device 14 to display candidate communication partner numbers on the display unit 23. The candidate communication partner numbers are the terminal number of the activated terminal device 14 and the group number permitted to communicate.

FIG5B is a diagram showing a group table 302. The group table 302 is a table used by the server device 11 to manage groups. Each group is identified by a uniquely assigned identification number (group number). The group table 302 stores the group number and the terminal number of the terminal device 14 (belonging terminal device) belonging to the group for each group. The number of terminal devices 14 belonging to a group can be one or more. The groups registered in the group table 302 correspond to the original groups of the present invention. The terminal table 301 and group table 302 are set on the server device 11 by the administrator operating the management device 12.

Figure 5C shows a hybrid table (session table) 303. Hybrid table 303 is a table used by server device 11 to manage communication sessions. A communication session is the communication status between multiple terminal devices 14 using server device 11 as a relay. Hybrid table 303 has multiple rows, each storing information about a single communication session. When server device 11 receives a voice signal (voice packet) from a terminal device 14, it refers to hybrid table 303 to determine which communication session the voice signal belongs to.

When the server device 11 receives the calling voice data packet as the first voice data packet from the terminal device 14 , the server device 11 registers the communication session based on the voice data packet in the mixed table 303 .

In the mixed table 303, for each communication session, items including a session number, a calling terminal number, a participating terminal number, an additional terminal number, an excluded terminal number, and a remaining holding time (T1) are provided. The session number is a number that identifies the communication session. The calling terminal number is the terminal number of the terminal device 14 (calling terminal device) that sent the initial voice data packet (call voice data packet) of the communication session. The session number only needs to be a unique value for each communication session. In this embodiment, the communication party identification number written in the above-mentioned call voice data packet is used. A communication session in which a terminal number is registered as a session number (for example, "19") is a communication session for single communication. Single communication refers to one-to-one communication between single terminal devices 14. A communication session in which a group number is registered as a session number (for example, "G1") is a communication session for group communication. Group communication refers to communication in which multiple terminal devices 14 (generally more than three) exchange voice signals with each other.

The participating terminal numbers are a list of the terminal numbers of the terminal devices 14 participating in the communication session. When a voice packet is transmitted from a terminal device 14 whose terminal number is registered in the participating terminal numbers, the control unit 30 forwards the voice packet to another terminal device 14 whose terminal number is registered in the participating terminal numbers, thereby enabling mutual communication between the participating terminal devices.

In the case of a group communication session, the participating terminal numbers are the terminal numbers of the calling terminal device and the terminal numbers of the terminal devices 14 belonging to the group designated as the communication partner. However, since terminal devices 14 belonging to the group but not active, or terminal devices 14 currently engaged in other individual communication sessions, cannot participate in the group communication session, the terminal numbers of these terminal devices 14 are excluded from the participating terminal numbers (registered in the excluded terminal number column). Furthermore, if the calling terminal device is a terminal device 14 that does not belong to the group, that is, if the terminal device 14 calls a group other than the one it belongs to, the terminal number of this terminal device 14 is also registered as the participating terminal number. Furthermore, the terminal numbers of additional terminal devices that have been temporarily registered as members are also registered in the additional terminal number column. In other words, in the group communication session, even if the calling terminal device does not belong to the group, it is treated as a terminal device 14 participating in the communication session (a participating terminal device) in the same manner as terminal devices 14 belonging to the group. The columns for additional terminal numbers and excluded terminal numbers in the entries of the mixed table 303 are not required. Table management can be achieved simply by adding or removing terminal numbers in the column of participating terminal numbers.

In the case of a single communication session, the terminal number of the calling terminal device and the terminal number of the communicating party's terminal device 14 are registered as participating terminal numbers. Since it is a one-to-one communication, the additional terminal number and the excluded terminal number are not registered.

The hold time is the time during which the communication session is maintained without canceling it even if no voice data packets are sent from the participating terminal devices. The hold time for each communication session in the server device 11 is set to 30 seconds, for example. The hold time timer (TS) of the mixed table 303 is a timer that counts the elapse of the hold time when no voice data packets are sent. In the processing performed by the control unit 30 (see FIG. 7 ), the hold time timer TS counts down if no voice data packets are sent, and is reset to 30 seconds if a voice data packet is sent. If the timer TS expires due to no voice data packets being sent from the participating terminal devices within 30 seconds, the communication session is canceled, and the information about the communication session is deleted from the mixed table 303.

In the above example, in a group communication session, the calling terminal device is registered in addition to the affiliated terminal device in the participating terminal device field of the mixed table 303, while inactive terminal devices 14, even though affiliated terminal devices, and terminal devices 14 currently in other communication sessions are excluded. However, the terminal devices 14 that are additionally registered in the participating terminal device field and the terminal devices 14 that are excluded are not limited to these cases.

If a participating terminal device starts another communication session (single communication session) during a group communication session, it is excluded from the participating terminal devices of the group communication session at that point in time. In other words, the terminal number of the terminal device 14 is moved from the participating terminal number column to the excluded terminal number column.

Furthermore, in order to continue the communication session, each terminal device 14 also needs to measure a hold time. The hold time (T1) of the terminal device 14 is shorter than the hold time (TS = 30 seconds) of the server device 11. For example, timer T1 is set to 5 seconds. If 5 seconds have passed since the user turned off the PTT switch 220, even if the communication session on the server device 11 is maintained, another communication session can be started by a predetermined operation.

In addition, the mixing table 303 can be divided into two tables consisting of an ongoing mixing table and a backoff table. The ongoing mixing table is a table that registers the currently ongoing mixing session and is formed on a high-speed memory. The session whose communication (transmission and reception of voice data packets) is interrupted is transferred to the backoff table in a short time of about 200 milliseconds and is maintained in the backoff table for a holding time (T1). If communication (transmission and reception of voice data packets) occurs again during the holding time, the session is transferred to the ongoing mixing table again for the execution of mixing. In this way, the release of each terminal device 14 from the mixing table 303 can be advanced.

FIG6 is a flowchart illustrating the communication control process executed by the control unit 20 of the terminal device 14. This process is repeated every 20 milliseconds. In this process, the current communication status is estimated based on the on/off state of the PTT switch 220 and the reception of audio packets (RTP packets). The flags and timers used in this flowchart are as follows.

PTT: is an abbreviation of the push-to-talk switch (PTT switch) 220, but is not limited to the on/off of the PTT switch 220, and also includes the on/off of the transmission signal based on the VOX circuit.

NC0: The identification number (terminal number/group number) of the communication partner selected by the user

NC1: Session number used, a number for identifying the communication session in progress, and the identification number (terminal number/group number) of the communication partner written in the first voice packet for establishing the communication session.

FC: Communication session flag (a flag indicating that the terminal device 14 is participating in a communication session)

FT: Communication flag (a flag indicating that a voice packet is being sent or received)

T1: Hold time timer (a timer for counting the hold time (5 seconds) of a communication session)

S10 to S20 are voice packet transmission management processes. The control unit 20 determines the state of the PTT switch 220 (S10). If the PTT switch 220 is on, the control unit 20 advances the process to S11. If the PTT switch 220 is not on, the process advances to S20.

In S11, the control unit 20 determines whether the communication session flag FC is set. If the communication session flag FC is not set (No in S11), the voice data packet created by turning on the PTT switch 220 this time is a call voice data packet. The control unit 20 sets the communication session flag FC and the communication flag FT indicating that the voice data packet is being transmitted or received (S12). The control unit 20 transfers the communication partner number NC0 selected by the user to the communication session number NC1 (S13), and transmits the voice data packet with the communication session number NC1 written into the data body along with the voice signal to the server device 11 (S14). By transmitting this call voice data packet, the server device 11 starts a communication session. After resetting the hold time timer T1 to 5 seconds (S15), the control unit 20 advances the processing to the voice data packet reception management processing after S30.

If the communication session flag FC is set in S11 (Yes in S11), the control unit 20 determines whether the communication flag FT is set, that is, whether a voice packet is currently being transmitted or received (S16). If the communication flag FT is not set (No in S16), the control unit 20 sets the communication flag FT (S17). The processing proceeds from S11 to S16 to S17, which means that the transmission of a new voice packet (the user's conversation voice) is started while the already-started communication session is maintained. In S18, it is determined whether to continue the already-started communication session and return the current voice packet to the communication session (No in S18), or to terminate the previous communication session and send the current voice packet to a new communication partner, that is, to establish a new communication session (Yes in S18). This determination can be made, for example, based on whether the user performed an operation, such as selecting the communication partner, immediately before the current PTT switch 220 was turned on. When the user performs an operation of selecting a new communication partner, in the process of S19 , a process of establishing a new communication session with the selected communication partner may be performed.

If the communication session is to be updated (YES in S18), the control unit 20 transfers the currently selected communication partner number NC0 to the communication session number NC1 (S19) and proceeds to S14. If the communication session that has already started is to be continued (NO in S18), the control unit 20 proceeds directly from S18 to S14.

If the PTT switch 220 is not on in S10 (No in S10), the control unit 20 resets the communication flag FT (S20). If the communication flag FT has already been reset, the status quo can be maintained. The control unit 20 then advances the process to the voice packet reception management process from S30 onwards.

In S30, the control unit 20 determines whether a voice packet has been received via the network 17. If a voice packet has been received, the control unit 20 advances the process to S31. If a voice packet has not been received, the control unit 20 advances the process to S40.

In S31, the control unit 20 determines whether the communication session flag FC is set. If the communication session flag FC is not set (No in S31), it determines that a new communication session has been established and its initial voice packet has been sent. The control unit 20 sets the communication session flag FC and the communication in progress flag FT (S33). The FT flag indicates that a voice packet is currently being transmitted or received. The control unit 20 transfers the communication partner number contained in the voice packet to the communication session number NC1 (S34). The control unit 20 outputs the voice packet to the audio circuit 24 (S35) and resets the hold timer T1 to 5 seconds (S36).

If the communication session flag FC is already set in S31 (Yes in S31), the control unit 20 sets the communication flag FT in response to the reception of the current voice packet (S32). If the communication flag FT is already set, the current state can be maintained. The control unit 20 then advances the process to S35.

If no audio data packet is received in S30 (No in S30), the control unit 20 determines whether the communication session flag FC is set (S40). If the communication session flag FC is set (Yes in S40), the control unit 20 executes the processing from S41 onwards. If the communication session flag FC is not set (No in S40), the control unit 20 immediately terminates the processing.

In S41, the control unit 20 determines whether the communication flag FT is set. If the communication flag FT is set (Yes in S41), the control unit 20 immediately terminates the process. If the communication flag FT is not set (No in S41), that is, if the communication flag FT is reset but the communication session flag FC is set, the control unit 20 decrements the hold time timer T1 by 1 (20 milliseconds) (S42). Then, the control unit 20 determines whether the hold time timer T1 has reached 0 due to this subtraction (S43). If the hold time timer T1 has reached 0 (Yes in S43), the control unit 20 resets the communication session flag FC to cancel the communication session (S44). If the hold time timer T1 is still greater than 0 in S43 (No in S43), the control unit 20 immediately terminates the process.

7A and 7B are flowcharts showing the operation of the server device 11. Fig. 7A shows the processing when receiving a voice packet, and Fig. 7B shows the mixing table management processing.

In FIG7A , upon receiving a voice packet, the control unit 30 determines whether the communication session, identified by the source terminal number and the communication partner number, is already registered in the hybrid table 303 ( S50 ). If the communication session is already registered in the hybrid table 303 ( YES in S50 ), the control unit 30 forwards the voice signal contained in the received voice packet to the terminal device 14 participating in the communication session based on the participating terminal number in the hybrid table 303 ( S56 ). The control unit then resets the hold timer TS for the communication session in the hybrid table 303 to 30 seconds ( S57 ).

If the communication session for the received voice packet is not registered in mixed table 303 (No in S50), that is, if the voice packet is a call voice packet, a new communication session based on the call voice packet is registered in mixed table 303 (S51). At this time, the communication partner number is registered as the session number, and the terminal number of the terminal device 14 that sent the voice packet is registered as the calling terminal number. As participating terminal numbers, in the case of a single communication session, the communication partner number and the calling terminal number are registered. In the case of a group communication session, the calling terminal number and the terminal numbers of the terminal devices 14 belonging to the group of the communication partner number are registered. In addition, if the calling terminal device does not belong to the group, the calling terminal number is also registered in the additional terminal number. Furthermore, if there is a terminal device 14 belonging to the group that cannot participate in the communication session due to inactivity or being involved in another communication session, its terminal number is excluded from the participating terminal number item and transferred to the excluded terminal number item.

The control unit 30 transfers the audio signal of the received audio packet to the terminal device 14 participating in the communication session (S52). The terminal device 14 participating in the communication session is determined from the participating terminal numbers of the communication session registered in the mixed table 303.

The control unit 30 determines whether a terminal device 14 that has been excluded from the participating terminal devices of the previously registered communication session due to participating in the communication session established in S51 exists (S53). If a corresponding terminal device 14 exists (YES in S53), the terminal number of the terminal device 14 is deleted from the participating terminal numbers of the previously established communication session (S54). The excluded terminal number is transferred to the excluded terminal number. This optimizes the participating terminal devices of each communication session.

The mixed table management process shown in FIG7B is repeatedly executed periodically (e.g., every 20 milliseconds). The control unit 30 first specifies the communication session in the first row of the mixed table 303 (S60). The control unit 30 decrements the hold time timer TS for the specified communication session by 1 (20 milliseconds) (S61) and determines whether the hold time timer TS has reached 0 as a result of this subtraction (S62). If the hold time timer TS has reached 0 (YES in S62), the control unit 30 deems the communication session to have ended and deletes the communication session in that row (S63).

The control unit 30 sequentially executes the above-described processing until the final row of the hybrid table 303 ( S64 , S65 ), thereby managing the hybrid table 303 .

In the voice communication system of this embodiment, the members (participating terminal devices) of a group communication session are not fixed but flexible. For example, a calling terminal device can participate in a group communication even if it does not belong to the group. Furthermore, even during a group communication, a user can exit the group communication and join another communication session. This enables group calls that are tailored to the real-time communication status of each terminal device.

In the above embodiment, it is also possible to enable a terminal device 14 to join a group communication session midway. For example, if a group communication session is being conducted solely by a terminal device 14 belonging to a group, and a call audio packet is sent to the group from a terminal device 14 not belonging to the group, the terminal device 14 can be enabled to join the currently ongoing group communication session, thereby changing the session format to an extended group communication session. Furthermore, if a call audio packet is sent to the group (the extended group) from another terminal device 14 not belonging to the group during the extended group communication session, the terminal device 14 can be further enabled to join the currently ongoing extended group communication session.

In the above embodiment, in group communication and extended group communication, an inactive terminal device is excluded from the communication session as an excluded terminal device. However, the terminal device may be allowed to participate in the communication session when it becomes active.

In the above embodiment, extended group communication between groups can also be performed. For example, by having a terminal device belonging to a certain group call another group on behalf of the group, the server device 11 establishes a communication session of an extended group consisting of all terminal devices of the group to which the terminal device belongs and the called group.

In the above embodiment, a communication session is established in response to a call audio packet transmitted from terminal device 14. However, the trigger for establishing a communication session is not limited to this. For example, an administrator can establish and cancel mixed groups by manipulating mixed table 303 via management device 12. Furthermore, management device 12 can also establish and cancel extended group communications between groups as described above. This approach also enables comprehensive management and flexible modification of mixed groups.

Explanation of symbols

11 Server device (relay device)

12 Management Device

13 Wireless Access Points

14 Terminal Devices

20 Control unit (of terminal device)

30 Control unit (of the server device)

32 Network Communications Department

220 PTT (Push to Talk) switch

301 Terminal Form

302 Group Table

303 Hybrid Form (Session Form)

Claims (15)

1. A relay device, comprising: The network communications department communicates with terminal devices via a network; The control unit controls communication sessions involving multiple terminal devices; and The storage department has a session table set up. The session table records session information, including information about the terminal devices participating in the communication session, i.e., the participating terminals. In the event that audio signals are received simultaneously from two or more participating terminals during the communication session, the control unit sends a mixed audio signal to each terminal device. The relay device is characterized in that... The network communication unit receives from the terminal device an audio signal containing additional information specifying the terminal device of the other party. When the control unit receives the initial audio signal of the first communication session from the terminal device, it registers in the session table the terminal device that sent the audio signal and the session information of the terminal device specified by the specified information attached to the audio signal as participants in the first communication session of the terminal. When the control unit receives the initial audio signal of the second communication session during the continuation of the first communication session, it also registers in the session table the terminal device that sent the audio signal and the session information of the second communication session as a participating terminal, as specified by the designated information attached to the audio signal. If the participating terminal of the first communication session is included in the participating terminal of the second communication session, the control unit removes the terminal device that became a participating terminal of both the first and second communication sessions from the participating terminal of the first communication session. 2. The relay device according to claim 1, characterized in that, In the mixing process, the control unit sends a signal to the terminal device that transmits the sound signal, which is a mixture of received sound signals other than the sound signal transmitted from the terminal device. 3. The relay device according to claim 1 or 2, characterized in that, If the control unit fails to receive an audio signal from any of the participating terminals in the communication session for a given period of time, it considers the communication session to have ended and deletes the session information of the communication session from the session table. 4. The relay device according to claim 1, characterized in that, The storage unit also contains a group table that stores the original groups to which multiple terminal devices belong. If the specified information attached to the initial sound signal received from the terminal device is information specifying the original group, the control unit registers the terminal device that sent the sound signal and the terminal devices belonging to the original group as the participating terminals in the session table of the storage unit. 5. A voice communication system, comprising: The terminal device includes a microphone, a sound output unit, and a terminal network communication unit; and The relay device includes a network communication unit, a control unit, and a storage unit. The terminal network communication unit of the terminal device and the network communication unit of the relay device transmit and receive voice signals via a network. The voice communication system is characterized in that... The terminal device adds information specifying the other party's terminal device to the audio signal input from the microphone, and transmits it to the relay device using the terminal network communication unit. The control unit controls the communication session in which multiple terminal devices participate. A session table is provided in the storage section of the relay device. The session table records session information, including information about the terminal devices participating in the communication session, i.e., the participating terminals. In the event that audio signals are received simultaneously from two or more participating terminals during the communication session, the control unit sends a mixed audio signal to each terminal device. The network communication unit of the relay device receives an audio signal with the specified information attached from the terminal device. When the control unit receives the initial audio signal of the first communication session from the terminal device, it registers in the session table the terminal device that sent the audio signal and the session information of the terminal device specified by the specified information attached to the audio signal as participants in the first communication session of the terminal. When the control unit receives the initial audio signal of the second communication session during the continuation of the first communication session, it also registers in the session table the terminal device that sent the audio signal and the session information of the second communication session as a participating terminal, as specified by the designated information attached to the audio signal. If the control unit includes a participating terminal of the first communication session in the participating terminals of the second communication session, it removes the terminal device that became a participating terminal of both the first and second communication sessions from the participating terminals of the first communication session. The sound reproduction unit of the terminal device reproduces the sound signal received from the relay device. 6. The voice communication system according to claim 5, characterized in that, The terminal device also has a one-button circuit. The terminal network communication unit transmits the sound signal input from the microphone to the relay device while the one-touch circuit is on, and receives the sound signal sent from the relay device regardless of whether the one-touch circuit is on or off. 7. The voice communication system according to claim 5, characterized in that, The network has multiple access points for a wireless local area network. The terminal network communication unit of the terminal device connects to the network via any access point. 8. A recording medium storing a computer program, characterized in that the computer program enables a computer equipped with a network communication unit for communicating with a terminal device via a network and a storage unit containing a session table to function as a unit that... The first unit, upon receiving an initial sound signal, i.e. a call sound signal, from the terminal device, which includes information specifying the terminal device of the communication counterpart, registers in the session table the terminal device that sent the call sound signal and the terminal device specified by the information specified in the call sound signal as participants in the communication session of the terminal. The second unit forwards the audio signal received from the participating terminal, which includes the call audio signal, to each participating terminal; and The third unit, when simultaneously receiving audio signals from two or more participating terminals, mixes these audio signals and sends the mixed audio signal to the participating terminals. After registering the session information of the first communication session based on the first call sound signal to the session table, if the first unit further receives the second call sound signal, it further registers the session information of the second communication session based on the second call sound signal to the session table. If the participating terminal of the second communication session includes the participating terminal of the first communication session, the terminal device that became the participating terminal of both the first and second communication sessions is removed from the participating terminal of the first communication session. 9. The recording medium according to claim 8, characterized in that, In the mixing process, the third unit sends a signal to the terminal device that sent the sound signal, which is a mixture of received sound signals other than the sound signal sent from the terminal device. 10. The recording medium according to claim 8 or 9, characterized in that, If the first unit fails to receive an audio signal from any of the participating terminals in the communication session and a given time has elapsed, it considers the communication session to have ended and deletes the session information of the communication session from the session table. 11. The recording medium according to claim 8, characterized in that, The storage unit also contains a group table that stores the original groups to which multiple terminal devices belong. If the specified information attached to the initial sound signal received from the terminal device is information specifying the original group, the first unit registers the terminal device that sent the sound signal and the terminal device belonging to the original group as the communication session of the participating terminal in the session table of the storage unit. 12. A method for relaying audio signals, comprising a relay device having a network communication unit that communicates with a terminal device via a network and a storage unit having a session table configured, for relaying audio signals. The method for relaying the sound signal is characterized by comprising: In the first step, when the relay device receives the initial voice signal, i.e., the call voice signal, which is attached with information specifying the terminal device of the communication counterpart from the terminal device, it registers the terminal device that sent the call voice signal and the terminal device specified by the information attached to the call voice signal as the communication session information of the participating terminal in the session table. In the second step, the relay device forwards the audio signal received from the participating terminal, which includes the call audio signal, to each participating terminal; and In the third step, when the relay device receives audio signals simultaneously from two or more participating terminals, it mixes these audio signals and sends the mixed audio signal to the participating terminals. In the first step, after registering the session information of the first communication session based on the first call sound signal to the session table, if the relay device further receives the second call sound signal, it further registers the session information of the second communication session based on the second call sound signal to the session table. If the participating terminal of the second communication session includes the participating terminal of the first communication session, the terminal device that became the participating terminal of both the first and second communication sessions is removed from the participating terminal of the first communication session. 13. The method for relaying audio signals according to claim 12, characterized in that, In the third step, during the mixing process, a signal is sent to the terminal device that sent the sound signal, consisting of a mixture of received sound signals other than the sound signal sent from the terminal device. 14. The method for relaying audio signals according to claim 12 or 13, characterized in that, In the first step, if no sound signal is received from any of the participating terminals in the communication session and a given time has elapsed, the communication session is considered to have ended, and the session information of the communication session is deleted from the session table. 15. The method for relaying sound signals according to claim 12, characterized in that, In the first step, if the specified information attached to the initial sound signal received from the terminal device is information about the original group to which multiple terminal devices belong in advance, the terminal device that sent the sound signal and the terminal device belonging to the original group are registered in the session table of the storage unit as the communication session of the participating terminal.