Communication system

Abstract

To provide a technique for suppressing the generation of unnecessary traffic when a terminal device on a receiving side is incapable of voice calls.SOLUTION: A second terminal device 100b determines whether or not a voice call is possible based on the strength of a signal received from a second base station device 200b, and transmits a determination result to a server 500. The server 500 manages the determination result as a reception status. A first terminal device 100a transmits a call request signal to a server 400. If the reception status indicates that a voice call is possible, the server 400 transmits a calling signal to the second terminal device 100b.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to communication technology, and more particularly to a communication system that provides voice calls.

Background Art

[0002] The PTT (Push to Talk) function is a function that provides a user experience similar to that of a half-duplex radio. Without entering a phone number or the like, the user can simply press a call button to place a call to multiple other users and speak. For other users, the voice output of the speaking content can be heard from the user's mobile phone without pressing a response button. The service that provides the PTT function via a mobile communication network is the PoC (Push-to-Talk over Cellular) service (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a Proof of Concept (PoC), a terminal device (PoC terminal) with a session set up on the PoC server receives voice signals. However, if the terminal device is located near the fringe (in a weak signal environment), it may fail to receive voice signals or voice calls may not be possible. Taking the LTE (Long Term Evolution) communication system as an example, a terminal device generally receives a reference signal (CRS (Cell-specific Reference Signal)) broadcast from the base station device, measures RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality), and reports the measurement results to the base station device. The base station device disconnects the RRC (Radio Resource Control) connection in the radio bearer section with the terminal device according to the measurement results. However, even if the RRC connection is disconnected, the mobile communication network maintains the EPS (Evolved Packet System) bearer of the core network. Therefore, when attempting to make a call (establish a session for PoC communication) from the transmitting terminal device (hereinafter referred to as "the first terminal device") to the receiving terminal device (hereinafter referred to as "the second terminal device"), the PoC server attempts to set up a session with the second terminal device. This process is performed even if the second terminal device is located near the fringe and therefore unable to make a voice call. As a result, if the receiving terminal device is unable to make a voice call, unnecessary traffic is generated.

[0005] This invention has been made in view of these circumstances, and its purpose is to provide a technology that suppresses the generation of unnecessary traffic when the receiving terminal device is unable to make voice calls. [Means for solving the problem]

[0006] To solve the above problems, a communication system according to one aspect of the present invention comprises a first terminal device and a second terminal device capable of voice calls, a first base station device capable of wireless communication with the first terminal device, a second base station device capable of wireless communication with the second terminal device, a core network connecting the first base station device and the second base station device and establishing a communication network with each of the first and second terminal devices, and a server connected to the core network, which manages calls between the first and second terminal devices and manages the reception status of signals from the second base station device at the second terminal device. The second terminal device determines whether or not a voice call is possible based on the strength of the signal received from the second base station device, and transmits the determination result to the server. When the server receives the determination result from the second terminal device, it manages the determination result as a reception status. The first terminal device transmits a call request signal to the server when initiating a call with the second terminal device, and if the reception status indicates that a voice call is possible, the server transmits a call signal to the second terminal device via the core network and the second base station device.

[0007] Another aspect of the present invention is a communication system. This communication system comprises a first terminal device and a second terminal device capable of voice communication, a first base station device capable of wireless communication with the first terminal device, a second base station device capable of wireless communication with the second terminal device, a core network connecting the first base station device and the second base station device and establishing a communication network with each of the first and second terminal devices, and a server connected to the core network, which manages calls between the first and second terminal devices and manages the reception status of signals from the second base station device at the second terminal device. The second terminal device measures the strength of the signal received from the second base station device and transmits the strength information to the server. When the server receives the strength information from the second terminal device, it manages the strength information as a reception status. The first terminal device transmits a call request signal to the server when initiating a call with the second terminal device. If the reception status indicates a strength suitable for voice communication, the server transmits a call signal to the second terminal device via the core network and the second base station device.

[0008] A communication system according to another aspect of the present invention comprises a first terminal device and a second terminal device capable of voice communication, a first base station device capable of wireless communication with the first terminal device, a second base station device capable of wireless communication with the second terminal device, a core network connecting the first base station device and the second base station device and establishing a communication network with each of the first and second terminal devices, a first server connected to the core network and managing calls between the first and second terminal devices, and a second server connected to the core network and managing the reception status of signals from the second base station device at the second terminal device. The second terminal device determines whether a voice call is possible based on the signal strength received from the second base station device, and transmits the determination result to the second server. The second server, upon receiving the determination result from the second terminal device, manages the determination result as a reception status. The first terminal device sends a call request signal to the first server when initiating a call with the second terminal device. The first server, upon receiving the call request signal from the first terminal device, obtains the reception status from the second server. If the reception status indicates that a voice call is possible, the first server transmits a call signal to the second terminal device via the core network and the second base station device.

[0009] Furthermore, any combination of the above components, as well as conversions of the expression of the present invention between methods, apparatus, systems, recording media, computer programs, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the generation of unnecessary traffic when the receiving terminal device is unable to make voice calls. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram shows the configuration of the communication system according to the embodiment. [Figure 2] This diagram shows the configuration of the terminal device shown in Figure 1. [Figure 3] This diagram shows the configuration of the first server in Figure 1. [Figure 4]This is a flowchart showing the reporting procedure using the second terminal device in Figure 1. [Figure 5] Figure 1 is a flowchart showing the processing procedure performed by the first server. [Modes for carrying out the invention]

[0012] Before describing this embodiment in detail, let's first give an overview. This embodiment relates to a communication system for performing a Proof of Concept (PoC). In the communication system, a first terminal device and a second terminal device are connected to a core network, and an EPS bearer is configured in the core network. The first server, which is the aforementioned PoC server, is also connected to the core network. The second terminal device determines whether or not voice communication is possible based on the signal strength received from the base station device and transmits the determination result to the second server connected to the core network. The second server stores the received determination result as the reception status of the second terminal device.

[0013] In this situation, the first terminal device sends a call request signal to the first server to request the initiation of a voice call with the second terminal device. Upon receiving the call request signal, the first server obtains the reception status of the second terminal device from the second server. If the reception status of the second terminal device indicates that a call is possible, the first server sends a ringing signal to the second terminal device using an EPS bearer. The second terminal device responds to the ringing signal, and a voice call is made between the first and second terminal devices. On the other hand, if the reception status of the second terminal device indicates that a call is not possible, the first server does not send a ringing signal to the second terminal device. In other words, by having the first server determine whether or not to conduct a PoC voice call, unnecessary traffic generated from the first server to the second terminal device is suppressed.

[0014] Figure 1 shows the configuration of the communication system 1000. The communication system 1000 includes a first terminal device 100a and a second terminal device 100b, collectively referred to as terminal devices 100; a first base station device 200a and a second base station device 200b, collectively referred to as base station devices 200; a core network 300; a first server 400; and a second server 500. The number of terminal devices 100 and base station devices 200 included in the communication system 1000 is not limited to "2".

[0015] The communication system 1000 is a PoC system that uses the data communication function of a mobile communication system such as LTE (Long Term Evolution) or 5G. The first terminal device 100a is a wireless communication device used by a user (hereinafter also referred to as "first user") and communicates with the first base station device 200a using a mobile communication wireless communication method. The second terminal device 100b is a wireless communication device used by a user (hereinafter also referred to as "second user") and communicates with the second base station device 200b using a mobile communication wireless communication method. Here, it is assumed that the first terminal device 100a is the transmitting terminal device 100, the second terminal device 100b is the receiving terminal device 100, and that voice calls are made between the first terminal device 100a and the second terminal device 100b.

[0016] The first base station device 200a is a base station device 200 capable of wireless communication with the first terminal device 100a and is also connected to the core network 300. The second base station device 200b is a base station device 200 capable of wireless communication with the second terminal device 100b and is also connected to the core network 300. Here, as an example, the first terminal device 100a and the second terminal device 100b are connected to different base station devices 200, but the first terminal device 100a and the second terminal device 100b may also be connected to the same base station device 200.

[0017] The core network 300 is a network of a mobile communication system that connects the first base station device 200a and the second base station device 200b. In LTE, the core network 300 is called EPC (Evolved Packet Core), and sets up EPS bearers with each of the first terminal device 100a and the second terminal device 100b. In 5G, the core network 300 is called 5GC (5th Generation Core Network), and sets up PDU (Protocol Data Unit) sessions with each of the first terminal device 100a and the second terminal device 100b. For the setup of EPS bearers and PDU sessions in the core network 300, known technologies may be used, so the description is omitted here. Hereinafter, the description will be made assuming that the communication method is LTE.

[0018] The first server 400 is connected to the core network 300 and manages calls between the first terminal device 100a and the second terminal device 100b. Also, the first server 400 manages the accounts of each terminal device 100 and controls PoC voice calls.

[0019] Hereinafter, the processing until the establishment of a voice call by PoC in such a communication system 1000 will be described while also using FIGS. 2 and 3. FIG. 2 is a diagram showing the configuration of the terminal device 100. The terminal device 100 includes a speaker 110, a microphone 112, a PTT button 114, a communication unit 116, a control unit 118, and a storage unit 120. The first terminal device 100a and the second terminal device 100b in FIG. 1 have the same configuration.

[0020] The communication unit 116 performs wireless communication corresponding to the aforementioned mobile communication system and communicates with the base station device 200. The operation of the communication unit 116 is controlled by the control unit 118. The storage unit 120 stores information used for wireless communication or PoC calls in the communication unit 116. For example, the storage unit 120 stores the address information of the present terminal device 100, the address information of other terminal devices 100 to be the destination, etc. Also, the storage unit 120 stores a threshold value to be compared with the signal strength. Such a threshold value may be set by the user.

[0021] The PTT button 114 is a button that can be pressed by the user. This can also be said to be an interface operated by the user using the terminal device 100. The PTT button 114 outputs the received operation to the control unit 118. When the PTT button 114 is pressed down, the communication unit 116 can transmit an audio signal. On the other hand, when the PTT button 114 is not pressed down, the communication unit 116 can receive an audio signal.

[0022] The microphone 112 acquires the voice generated by the user when the user presses down the PTT button 114. The microphone 112 converts the acquired voice into an electrical signal and outputs the converted voice (hereinafter referred to as "audio signal") to the control unit 118. When the user does not press down the PTT button, the control unit 118 receives an audio signal from the communication unit 116, converts the audio signal into voice, and outputs the voice from the speaker 110.

[0023] When the power of the second terminal device 100b is turned on, the control unit 118 causes the communication unit 116 to transmit a signal (hereinafter referred to as "connection request signal") for requesting connection to the core network 300. When the second base station device 200b receives the connection request signal, the second base station device 200b transmits the connection request signal to the core network 300. The core network 300 executes authentication of the second terminal device 100b based on the connection request signal. When the authentication is completed, the core network 300 transmits a signal (hereinafter referred to as "completion report signal") for notifying the completion of authentication to the second terminal device 100b via the second base station device 200b.

[0024] The communication unit 116 of the second terminal device 100b receives the completion report signal from the core network 300. The control unit 118 recognizes the completion of authentication with the core network 300 by the reception of the completion report signal in the communication unit 116. In addition, the second terminal device 100b performs PoC account authentication with the first server, and the communication unit 116 receives account information from the first server 400. The control unit 118 stores the account information received in the communication unit 116 in the storage unit 120.

[0025] When the communication unit 116 receives a signal from the second base station device 200b, such as a reference signal, it measures the signal strength. Specifically, in the case of LTE, the CRS (Common Reference Signal) can be used to measure the signal strength, and in the case of 5G, the CSI-RS (Channel State Information Reference Signal) can be used. The method of measuring the signal strength is not limited to these, and other signals may be used. The control unit 118 compares the signal strength received from the communication unit 116 with a threshold value stored in the storage unit 120. If the signal strength is greater than the threshold value, the control unit 118 determines that voice communication is possible. On the other hand, if the signal strength is below the threshold value, the control unit 118 determines that voice communication is not possible. The control unit 118 outputs the determination result, indicating whether voice communication is possible or not, to the communication unit 116. The communication unit 116 transmits the determination result to the second server 500 via the second base station device 200b and the core network 300.

[0026] The second server 500 is connected to the core network 300 and receives the determination results from the second terminal device 100b via the second base station device 200b and the core network 300. The second server 500 manages the determination results from the second terminal device 100b. The determination results from the second terminal device 100b can be considered the reception status at the second terminal device 100b for the signal from the second base station device 200b. The above operations are also performed at the first terminal device 100a.

[0027] When the first user of the first terminal device 100a initiates a call with the second user of the second terminal device 100b, the first user presses down the PTT button 114 on the first terminal device 100a. At this time, the second terminal device 100b, which is the destination, is selected by the first user's operation. The control unit 118 receives the request to start a call when the PTT button 114 is pressed. Upon receiving the request to start a call, the control unit 118 generates a call request signal. The call request signal includes the address information of the first terminal device 100a, the account information of the destination second terminal device 100b, and a request to establish a session for a voice call between the first terminal device 100a and the first server 400. The call request signal is a signal to request the start of a call with the second terminal device 100b. The communication unit 116 transmits the call request signal to the first server 400 via the first base station device 200a and the core network 300.

[0028] Figure 3 shows the configuration of the first server 400. The first server 400 includes a communication unit 416, a control unit 418, and a storage unit 420. The communication unit 416 receives a call request signal from the first terminal device 100a via the first base station device 200a and the core network 300. The control unit 418 sets up a session with the first terminal device 100a based on the address information and account information of the first terminal device 100a in the received call request signal. The control unit 418 also extracts the account information of the destination second terminal device 100b from the received call request signal. The control unit 418 generates a signal to inquire about the reception status of the second terminal device 100b (hereinafter referred to as the "inquiry signal") and outputs the inquiry signal to the communication unit 416. The inquiry signal also includes the address information of the second terminal device 100b. The communication unit 416 transmits the inquiry signal to the second server 500.

[0029] The second server 500 receives a query signal from the first server 400. The second server 500 obtains the address information of the second terminal device 100b included in the query signal. The second server 500 extracts the reception status of the second terminal device 100b corresponding to the obtained address information and sends a signal (hereinafter referred to as the "response signal") including the reception status of the second terminal device 100b to the first server 400.

[0030] The communication unit 416 of the first server 400 receives a response signal from the second server 500. The control unit 418 obtains the reception status of the second terminal device 100b included in the response signal. If the reception status indicates that a voice call is possible, the control unit 418 generates a call signal. The call signal includes the address information of the first terminal device 100a, which is the source, and the account information of the second terminal device 100b, which is the destination. The communication unit 416 uses an EPS bearer with the second terminal device 100b to transmit the call signal to the second terminal device 100b via the core network 300 and the second base station device 200b. At that time, the control unit 418 sets up a session with the second terminal device 100b. This enables a call between the first terminal device 100a and the second terminal device 100b by sending and receiving voice signals. Known technology can be used for this.

[0031] On the other hand, if the reception status indicates that voice communication is not possible, the control unit 418 does not generate a call signal, and the communication unit 416 does not transmit a call signal to the second terminal device 100b. As a result, no call is made between the first terminal device 100a and the second terminal device 100b. The control unit 418 may also store the voice signal from the first terminal device 100a.

[0032] This configuration can be implemented in hardware terms using the CPU, memory, and other LSIs of any computer, and in software terms using programs loaded into memory, but here we are depicting the functional blocks that are realized through the cooperation of these components. Therefore, it will be understood by those skilled in the art that these functional blocks can be implemented in various ways using hardware alone, software alone, or a combination of both.

[0033] The operation of the communication system 1000 with the above configuration will now be explained. Figure 4 is a flowchart of the reporting procedure by the second terminal device 100b. Power is turned on (S10). The control unit 118 receives notification of authentication completion with the core network 300 via the communication unit 116 (S12). The control unit 118 obtains account information from the first server 400 via the communication unit 116 (S14). The communication unit 116 measures the signal strength from the second base station device 200b (S16). If the strength is greater than the threshold (Y in S18), the communication unit 116 transmits a determination result that a call is possible (S20). On the other hand, if the strength is not greater than the threshold (N in S18), the communication unit 116 transmits a determination result that a call is not possible (S22). The determination result is stored in the second server 500 (S24). Next, the process returns to step S16, and steps S16 to S24 are repeated thereafter. Furthermore, if the result of step S18 is the same as the previous time, the submission of the result may be omitted.

[0034] Furthermore, in step S18, the determination result may be sent only if the signal strength from the second base station device 200b is greater than or less than the threshold. In this case, the determination result may be configured to send only the unique ID of the second terminal device 100b. For example, if the configuration is such that the unique ID of the second terminal device 100b is sent when the communication strength from the second base station device 200b is greater than the threshold, the second server 500 stores the determination result that the second terminal device 100b is able to communicate when it receives the unique ID of the second terminal device 100b, and is unable to communicate when it does not receive the unique ID of the second terminal device 100b. Furthermore, if the configuration is such that the unique ID of the second terminal device 100b is sent when the signal strength from the second base station device 200b is not greater than a threshold, the second server 500 stores a determination result that indicates the second terminal device 100b is unable to communicate when it receives the unique ID of the second terminal device 100b, and that the second terminal device 100b is able to communicate when it does not receive the unique ID of the second terminal device 100b. If the determination result is sent only when the signal strength from the second base station device 200b is greater than or less than a threshold, it is desirable to configure the system so that the determination result is sent when the signal strength from the second base station device 200b is greater than a threshold, assuming a situation where the second terminal device 100b and the second base station device 200b cannot communicate at all.

[0035] Figure 5 is a flowchart showing the processing procedure by the first server 400. The communication unit 416 receives a call request signal from the first terminal device 100a (S50). The control unit 418 sets up a session with the first terminal device 100a (S52). The control unit 418 identifies the second terminal device 100b as the other party (S54). The control unit 418 obtains the reception status of the second terminal device 100b from the second server 500 via the communication unit 416 (S56). If a call is possible (Y in S58), the control unit 418 sets up a session with the second terminal device 100b (S60). As a result, a voice call is performed between the first terminal device 100a and the second terminal device 100b (S62). On the other hand, if a call is not possible (N in S58), the control unit 418 stores the voice signal from the first terminal device 100a (S64).

[0036] (modified version) Previously, each terminal device 100 reflected whether or not a call was possible and transmitted the determination result to the second server 500. In contrast, in the modified version, the determination of whether or not a call is possible is made by the first server 400. The communication system 1000, terminal device 100, and first server 400 in the modified version are of the same type as those shown in Figures 1 to 3. This explanation will focus on the differences from the previous version.

[0037] When the communication unit 116 of the second terminal device 100b receives a signal from the second base station device 200b, such as a reference signal (CRS), it measures the signal strength. The control unit 118 generates a signal (hereinafter referred to as "strength information") that includes the signal strength received from the communication unit 116 and outputs the strength information to the communication unit 116. The communication unit 116 transmits the strength information to the second server 500 via the second base station device 200b and the core network 300.

[0038] The second server 500 receives signal strength information from the second terminal device 100b via the second base station equipment 200b and the core network 300. The second server 500 manages the signal strength information from the second terminal device 100b. The signal strength information from the second terminal device 100b can be considered the reception status at the second terminal device 100b for the signal from the second base station equipment 200b. This operation is also performed at the first terminal device 100a.

[0039] The communication unit 416 of the first server 400 receives a call request signal from the first terminal device 100a via the first base station device 200a and the core network 300. The control unit 418 sets up a session with the first terminal device 100a based on the address information and account information of the first terminal device 100a in the received call request signal. The control unit 418 also extracts the account information of the destination second terminal device 100b from the received call request signal. The control unit 418 generates an inquiry signal to inquire about the reception status of the second terminal device 100b and outputs the inquiry signal to the communication unit 416. The inquiry signal also contains the address information of the second terminal device 100b. The communication unit 416 transmits the inquiry signal to the second server 500.

[0040] The second server 500 receives a query signal from the first server 400. The second server 500 obtains the address information of the second terminal device 100b included in the query signal. The second server 500 extracts the reception status of the second terminal device 100b corresponding to the obtained address information and sends a response signal including the reception status of the second terminal device 100b to the first server 400.

[0041] The communication unit 416 of the first server 400 receives a response signal from the second server 500. The control unit 418 acquires the reception status of the second terminal device 100b, i.e., signal strength information, contained in the response signal. The control unit 418 compares the acquired signal strength information with a threshold value stored in the storage unit 420. If the signal strength information is greater than the threshold value, i.e., if the reception status indicates a signal strength sufficient for voice communication, the control unit 418 generates a call signal. The call signal includes the address information of the first terminal device 100a, which is the source, and the address information of the second terminal device 100b, which is the destination. The communication unit 416 uses an EPS bearer with the second terminal device 100b to transmit the call signal to the second terminal device 100b via the core network 300 and the second base station device 200b. At this time, the control unit 418 sets up a session with the second terminal device 100b. As a result, a call is performed between the first terminal device 100a and the second terminal device 100b by sending and receiving voice signals. This can be done using publicly known technologies.

[0042] On the other hand, if the signal strength information is below a threshold, that is, if the reception status indicates a signal strength that makes voice communication impossible, the control unit 418 does not generate a call signal, and the communication unit 416 does not transmit a call signal to the second terminal device 100b. As a result, no call is made between the first terminal device 100a and the second terminal device 100b. The control unit 418 may also store the voice signal from the first terminal device 100a.

[0043] According to this embodiment, even if an EPS bearer is set up with the receiving terminal device 100, the first server 400 does not send a call signal to the receiving terminal device 100 if it determines that a call is not possible at the receiving terminal device 100. This suppresses the generation of unnecessary traffic when the receiving terminal device is unable to make a voice call. Furthermore, even if an EPS bearer is set up with the receiving terminal device 100, the first server 400 does not send a call signal to the receiving terminal device 100 if the signal strength at the receiving terminal device 100 is such that a call is not possible. This suppresses the generation of unnecessary traffic when the receiving terminal device is unable to make a voice call. In addition, since the first base station device 200a and the second base station device 200b are identical, the degree of flexibility in configuration can be improved.

[0044] The present invention has been described above based on examples. In the examples, audio signals were described, but the invention is not limited thereto and may also be information signals such as data signals. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combination with each component and each processing process, and that such modifications also fall within the scope of the present invention.

[0045] In the above embodiment, the first server and the second server were described as separate entities, but it is also possible to configure the system so that the functions of the first and second servers are combined into a single server. Alternatively, the functions of the first and second servers may be distributed across multiple servers. [Explanation of Symbols]

[0046] 100 Terminal device, 110 Speaker, 112 Microphone, 114 PTT button, 116 Communication unit, 118 Control unit, 120 Storage unit, 200 Base station device, 300 Core network, 400 First server, 416 Communication unit, 418 Control unit, 420 Storage unit, 500 Second server, 1000 Communication system.

Claims

1. A communication system that provides PoC voice calls, A first terminal device and a second terminal device capable of voice calls, The first terminal device and the first base station device capable of wireless communication, The second terminal device and the second base station device capable of wireless communication, The first base station device and the second base station device are connected, and the first terminal device and the second terminal A core network that establishes a communication network with each of the end devices, Connected to the aforementioned core network, the PoC sound between the first terminal device and the second terminal device The system manages voice calls and the reception status of signals from the second base station device at the second terminal device. It includes a server that manages the system, The second terminal device determines whether to perform a voice call based on the signal strength received from the second base station device. Determine whether it is possible or not, and send the determination result to the server. When the server receives the determination result from the second terminal device, it will determine the reception status. The aforementioned determination results are managed, When the first terminal device initiates a PoC voice call with the second terminal device, it sends a call request message The number is sent to the server, The server, when the reception status indicates that voice calls are possible, communicates with the core network and the A call signal is transmitted to the second terminal device via the second base station device, and the reception status is voice-activated. If communication is impossible, regardless of the configuration status of the EPS bearer in the core network. The aforementioned call signal is not transmitted. Communication system.

2. The second terminal device is A memory unit that stores the threshold value of the signal strength, A communication unit that measures the signal strength from the second base station device, The signal strength measured by the communication unit is compared with the signal strength threshold, and the signal strength If the signal strength is greater than the threshold, it is determined that voice communication is possible, and if the signal strength is greater than the threshold A control unit that determines that voice communication is impossible in the following cases, Equipped with, The communication system according to claim 1.

3. A communication system that provides PoC voice calls, A first terminal device and a second terminal device capable of voice calls, The first terminal device and the first base station device capable of wireless communication, The second terminal device and the second base station device capable of wireless communication, The first base station device and the second base station device are connected, and the first terminal device and the second terminal A core network that establishes a communication network with each of the end devices, Connected to the aforementioned core network, the PoC sound between the first terminal device and the second terminal device The system manages voice calls and the reception status of signals from the second base station device at the second terminal device. It includes a server that manages the system, The second terminal device measures the strength of the signal received from the second base station device and provides information on the strength. The report is sent to the aforementioned server, When the server receives the intensity information from the second terminal device, it will determine the reception status and The system manages the intensity information and compares the intensity information with the stored threshold value to determine the voice signal. Determine whether or not communication is possible. When the first terminal device initiates a PoC voice call with the second terminal device, it sends a call request message The number is sent to the server, The server, when the reception status indicates a strength sufficient for voice communication, the core network A call signal is transmitted to the second terminal device via the second base station device, and the reception status is If the signal strength indicates that voice calls are impossible, then the configuration of the EPS bearer in the core network... Regardless of the state, the aforementioned call signal will not be transmitted. Communication system.

4. A communication system that provides PoC voice calls, A first terminal device and a second terminal device capable of voice calls, The first terminal device and the first base station device capable of wireless communication, The second terminal device and the second base station device capable of wireless communication, The first base station device and the second base station device are connected, and the first terminal device and the second terminal A core network that establishes a communication network with each of the end devices, The above-mentioned core network is connected, and the Po between the first terminal device and the second terminal device The first server manages C voice calls, Connected to the core network and corresponding to the signal from the second base station device It includes a second server that manages the reception status on two terminal devices, The second terminal device determines whether to perform a voice call based on the signal strength received from the second base station device. Determine whether it is possible or not, and send the determination result to the second server. When the second server receives the determination result from the second terminal device, it receives the reception status The aforementioned determination results are managed as follows: When the first terminal device initiates a PoC voice call with the second terminal device, it sends a call request message The number is sent to the first server, When the first server receives the call request signal from the first terminal device, the second The reception status is obtained from the server and then... The first server, when the reception status indicates that voice calls are possible, communicates with the core network and A call signal is transmitted to the second terminal device via the second base station device, and the reception status is sound If voice communication is unavailable, it depends on the configuration status of the EPS bearer in the core network. Regardless, the aforementioned call signal is not transmitted. Communication system.

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