Communication system, mobile terminal, program, and communication method

Abstract

In the present invention, in cases where a relay terminal (110) is present within a range (102) reached by radio waves from a base station (101) and a remote terminal (130) is present outside of the range (102) reached by radio waves from the base station (101), when emergency warning information for issuing notification of emergency situations is received from the base station (101), the relay terminal (110) transmits the emergency warning information to the remote terminal (130) using a connection established between the remote terminal (130) and the relay terminal (110) in order to communicate in a one-to-one manner using a physical sidelink shared channel (PSSCH).

Description

[Technical Field]

[0001] The present disclosure relates to a communication system, a mobile terminal, a program, and a communication method. [Background technology]

[0002] There have been technologies for transmitting highly urgent information from mobile phone network base stations to mobile devices. For example, the Public Warning System (PWS) is a method for transmitting emergency alert information standardized by the Third Generation Partnership Project (3GPP) to mobile devices via base stations. The Earthquake and Tsunami Warning System (ETWS) is a method for transmitting ETWS information, which is warning information about earthquakes and tsunamis, using the PWS mechanism.

[0003] By following the ETWS procedure, mobile devices that can communicate directly with a base station can receive ETWS information. However, mobile devices that are outside the range of the base station's radio waves cannot receive ETWS information using the ETWS procedure. Considering that ETWS information is important information related to people's safety, it is considered desirable to be able to send ETWS information to mobile devices that are outside the range of the base station's radio waves.

[0004] In 3GPP 5G NR (Fifth Generation New Radio), there is a UE (User Equipment)-to-Network Relay method that uses Side Link Relay communication in ProSe (Proximity-based Services) as shown in Non-Patent Document 1 in order to transmit ETWS information to a mobile terminal that is located outside the range where radio waves from a base station cannot reach.

[0005] In the UE-to-Network Relay scheme, a remote terminal, which is a mobile terminal located outside the coverage area of ​​a base station, communicates with the base station by using a relay function provided by a relay terminal, which is a mobile terminal that can communicate directly with the base station. For example, the relay terminal has a function to transfer short message information to the remote terminal and a function to transfer system information including SIB1, SIB6, and SIB7. Using these functions, when the relay terminal receives short messages, SIB1, SIB6, and SIB7, transmitted by the base station for ETWS, the relay terminal relays and transmits the information to the remote terminal. The remote terminal acquires ETWS information based on the contents of the short messages, SIB1, SIB6, and SIB7, relayed and transmitted by the relay terminal. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP TS 23.303 Proximity-based services Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional UE-to-Network Relay scheme, the base station, the relay terminal, and the remote terminal all need to support the UE-to-Network Relay scheme. Because base stations are mobile phone network infrastructure equipment that will be used for a long time, it may take time for them to support the UE-to-Network Relay method for 5G NR, which is being newly standardized by 3GPP. As a result, it may take time to create a mobile phone network environment that can transmit ETWS information to remote terminals using conventional methods.

[0008] Therefore, one or more aspects of the present disclosure aim to enable a relay terminal to transmit emergency alert information to a remote terminal even when a base station does not support the UE-to-Network Relay method. [Means for solving the problem]

[0010] A communication system according to a second aspect of the present disclosure is a communication system that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), and includes a base station, a first mobile terminal, and a second mobile terminal that can communicate with the first mobile terminal using ProSe (Proximity-based Services). When the first mobile terminal is present within a range reached by radio waves from the base station and the second mobile terminal is present outside the range reached by radio waves from the base station, upon receiving emergency alert information from the base station, which is information for notifying of an emergency situation, Apart from the timing of transmitting system information to the second mobile terminal, The broadcast message including the emergency alert information is transmitted to the second mobile terminal using a PSSCH (Physical Sidelink Shared CHannel).

[0011] A communication system according to a third aspect of the present disclosure is a communication system that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), and includes a base station, a first mobile terminal, and a second mobile terminal that can communicate with the first mobile terminal using ProSe (Proximity-based Services). When the first mobile terminal is located within a range of radio waves from the base station and the second mobile terminal is located outside the range of radio waves from the base station, the first mobile terminal, upon receiving emergency alert information from the base station, which is information for notifying an emergency situation, transmits the emergency alert information to the second mobile terminal using a connection established with the second mobile terminal for one-to-one communication using a PSSCH (Physical Sidelink Shared CHannel), and also transmits a broadcast message including the emergency alert information to the second mobile terminal using the PSSCH.

[0013] A mobile terminal according to a second aspect of the present disclosure is a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), and includes a communication unit that receives emergency alert information, which is information for notifying an emergency situation from a base station, and when the communication unit receives the emergency alert information, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, Apart from the timing of transmitting system information to the other mobile terminal, The mobile terminal is characterized by further comprising a control unit that causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using a PSSCH (Physical Sidelink Shared CHannel).

[0014] A mobile terminal according to a third aspect of the present disclosure is a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), and is characterized in that it comprises: a communication unit that receives emergency alert information, which is information for notifying an emergency situation from a base station; and a control unit that, when the communication unit receives the emergency alert information, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, causes the communication unit to transmit the emergency alert information to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using PSSCH (Physical Sidelink Shared CHannel), and causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using PSSCH.

[0016] A program according to a second aspect of the present disclosure includes a computer that functions as a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), a communication unit that receives emergency alert information that is information for notifying an emergency situation from a base station, and when the communication unit receives the emergency alert information, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, Apart from the timing of transmitting system information to the other mobile terminal, The present invention is characterized in that the control unit functions as a control unit that causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using a PSSCH (Physical Sidelink Shared CHannel).

[0017] A program according to a third aspect of the present disclosure is characterized in that it causes a computer that functions as a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project) to function as: a communication unit that receives emergency alert information, which is information for notifying an emergency situation, from a base station; and a control unit that, when the communication unit receives the emergency alert information, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, causes the communication unit to transmit the emergency alert information to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using PSSCH (Physical Sidelink Shared CHannel), and causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using PSSCH.

[0019] A communication method according to a second aspect of the present disclosure is a communication method performed by a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), and includes receiving emergency alert information, which is information for notifying an emergency situation, from a base station. When the emergency alert information is received, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, Apart from the timing of transmitting system information to the other mobile terminal, The broadcast message including the emergency alert information is transmitted to the other mobile terminal using a PSSCH (Physical Sidelink Shared CHannel).

[0020] A communication method according to a third aspect of the present disclosure is a communication method performed by a mobile terminal performing Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), which receives emergency alert information from a base station, which is information for notifying an emergency situation, and when the emergency alert information is received, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside the range of radio waves from the base station, the emergency alert information is transmitted to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using PSSCH (Physical Sidelink Shared CHannel), and a broadcast message including the emergency alert information is transmitted to the other mobile terminal using PSSCH. [Effects of the Invention]

[0021] According to one or more aspects of the present disclosure, even if a base station does not support the UE-to-Network Relay scheme, a relay terminal can transmit emergency alert information to a remote terminal. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a block diagram schematically showing a configuration of a wireless communication system according to first to sixth embodiments. [Figure 2] This is a sequence diagram showing the procedure for transmitting ETWS information by ETWS in 3GPP 5G NR between a base station and a relay terminal within the range of the base station's radio waves. [Figure 3] 2 is a block diagram schematically showing a configuration of a relay terminal in the first embodiment. FIG. [Figure 4] 10A and 10B are block diagrams showing an example of a hardware configuration. [Figure 5] FIG. 2 is a block diagram schematically showing a configuration of a remote terminal according to the first embodiment. [Figure 6] FIG. 4 is a sequence diagram showing a communication procedure of ETWS information in the first embodiment. [Figure 7] FIG. 10 is a block diagram schematically illustrating a configuration of a relay terminal according to a second embodiment. [Figure 8] FIG. 10 is a block diagram schematically illustrating a configuration of a remote terminal according to a second embodiment. [Figure 9] FIG. 10 is a sequence diagram showing a communication procedure of ETWS information in the second embodiment. [Figure 10] FIG. 11 is a block diagram schematically showing the configuration of a relay terminal in a third embodiment. [Figure 11] FIG. 11 is a block diagram schematically illustrating a configuration of a remote terminal according to a third embodiment. [Figure 12] FIG. 11 is a sequence diagram showing a communication procedure of ETWS information in the third embodiment. [Figure 13] FIG. 13 is a block diagram schematically showing the configuration of a relay terminal in a fourth embodiment. [Figure 14] FIG. 10 is a schematic diagram illustrating an example of ETWS information and a transmission end time. [Figure 15] FIG. 13 is a block diagram schematically illustrating a configuration of a relay terminal according to a fifth embodiment. [Figure 16] FIG. 20 is a block diagram schematically showing the configuration of a relay terminal in a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Embodiment 1 FIG. 1 is a block diagram schematically showing a configuration of a wireless communication system 100 according to the first embodiment. The wireless communication system 100 includes a relay terminal 110 and a remote terminal 130 . The wireless communication system 100 is a communication system that performs side link relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project).

[0024] 1, relay terminal 110 is a mobile terminal located within range 102 of radio waves from base station 101, and remote terminal 130 is a mobile terminal located outside the range of radio waves from base station 101. Relay terminal 110 is also referred to as a first mobile terminal, and remote terminal 130 is also referred to as a second mobile terminal.

[0025] The relay terminal 110 is capable of communicating directly with the base station 101 regardless of whether the UE-to-Network Relay scheme is used, and has a function of communicating using ProSe. The remote terminal 130 is located outside the range of the radio waves of the base station 101 and has the function of communicating with the relay terminal 110 via ProSe.

[0026] First, emergency information transmission using PWS will be described using the example of ETWS with reference to Fig. 2. Fig. 2 is a sequence diagram showing the procedure for transmitting ETWS information by ETWS in 3GPP 5G NR between base station 101 and relay terminal 110 located within radio wave coverage area 102 of base station 101.

[0027] First, the base station 101 transmits a short message indicating the presence of ETWS information to the relay terminal 110 on a communication channel of the PDCCH (Physical Downlink Control Channel) (S10). In this way, the base station 101 notifies the relay terminal 110 that the ETWS information exists.

[0028] Upon receiving the short message indicating the presence of ETWS information, the relay terminal 110 receives SIB (System Information Block) 1 transmitted on the BCCH (Broadcast Control Channel), which is a broadcast communication channel, in order to receive information indicating the transmission timing of the ETWS information (S11). This allows the relay terminal 110 to know the transmission timing of SIB6 and SIB7 indicating the ETWS information on the BCCH from the contents of the received SIB1.

[0029] Based on the transmission timings of SIB6 and SIB7 on the BCCH known in step S11, relay terminal 110 receives SIB6 and SIB7 on the BCCH (S12, S13). This allows relay terminal 110 to obtain the ETWS information.

[0030] If a mobile terminal is present within range 102 of radio waves from base station 101, ETWS information can be transmitted from base station 101 to the mobile terminal through the above procedure. Next, a case where ETWS information is transmitted to a mobile terminal that is outside the range of radio waves from the base station 101 will be described.

[0031] In the first embodiment, when a relay terminal 110 is present within a range 102 that can receive radio waves from a base station 101 and a remote terminal 130 is present outside the range 102 that can receive radio waves from the base station 101, the relay terminal 110 receives emergency alert information from the base station 101, which is information for notifying the remote terminal 130 of an emergency situation, and transmits the emergency alert information to the remote terminal 130 using the connection established with the remote terminal 130 for one-to-one communication using PSSCH. In the first embodiment, it is assumed that the connection between relay terminal 110 and remote terminal 130 is established before emergency alert information is received. Furthermore, if relay terminal 110 is to transmit system information to remote terminal 130, the establishment of a connection between relay terminal 110 and remote terminal 130 is to be performed at a timing different from the timing of transmitting the system information.

[0032] FIG. 3 is a block diagram schematically showing the configuration of relay terminal 110 according to the first embodiment. The relay terminal 110 includes a communication unit 111, a ProSe communication data processing unit 112, a ProSe communication connection control unit 113, a PSSCH communication connection recording unit 114, an ETWS processing unit 115, and an ETWS information transfer processing unit .

[0033] The communication unit 111 communicates with the base station 101 and the remote terminal 130. For example, the communication unit 111 transmits data plane and control plane messages to the remote terminal 130 on a communication channel used by ProSe. The communication unit 111 also receives ETWS information from the base station 101, which the base station 101 transmits using short messages and the BCCH.

[0034] The ProSe communication data processing unit 112 processes a communication protocol for transmitting messages between the data plane and the control plane on a communication channel used by ProSe. The ProSe communication data processing unit 112 passes necessary data (e.g., control plane messages) received by the communication unit 111 on the communication channel used by ProSe to the ProSe communication connection control unit 113.

[0035] The ProSe communication connection control unit 113 processes communication messages of the control plane, such as connection establishment and release, that are necessary for communication on a communication channel used by ProSe.

[0036] The PSSCH communication connection recording unit 114 records information about the remote terminal 130 to which the relay terminal 110 is currently connected as a result of the control plane processing for establishing and releasing a connection performed by the ProSe communication connection control unit 113 .

[0037] The ETWS processing unit 115 passes the ETWS information received by the communication unit 111 to the ETWS information transfer processing unit 116.

[0038] Upon receiving ETWS information from the ETWS processing unit 115, the ETWS information transfer processing unit 116 requests the ProSe communication data processing unit 112 to transmit an ETWS notification message including the ETWS information on the PSSCH to the remote terminal 130 with which a connection for one-to-one communication using the PSSCH has been established, based on the information recorded in the PSSCH communication connection recording unit 114.

[0039] Here, the ProSe communication data processing unit 112, the ProSe communication connection control unit 113, the ETWS processing unit 115, and the ETWS information transfer processing unit 116 are also referred to as a control unit 119. When emergency alert information is received, if there is a remote terminal 130, which is another mobile terminal that can communicate with the relay terminal 110 via ProSe, outside the range 102 reached by radio waves from the base station 101, the control unit 119 causes the communication unit 111 to transmit the emergency alert information to the remote terminal 130 using the connection established with the remote terminal 130 for one-to-one communication using PSSCH.

[0040] As shown in FIG. 4A, some or all of the ProSe communication data processing unit 112, ProSe communication connection control unit 113, ETWS processing unit 115, and ETWS information transfer processing unit 116 described above can be configured by a memory 10 and a processor 11, such as a CPU (Central Processing Unit), that executes a program stored in the memory 10. Such a program may be provided via a network or may be provided by being recorded on a recording medium. That is, such a program may be provided as, for example, a program product. In other words, the relay terminal 110 can be realized by a computer.

[0041] In addition, some or all of the ProSe communication data processing unit 112, the ProSe communication connection control unit 113, the ETWS processing unit 115, and the ETWS information transfer processing unit 116 can also be configured with a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), as shown in Figure 4(B). As described above, the ProSe communication data processing unit 112, the ProSe communication connection control unit 113, the ETWS processing unit 115, and the ETWS information transfer processing unit 116 can be realized by a processing circuit network.

[0042] Furthermore, the communication unit 111 can be realized by a wireless communication device having a wireless communication function. The PSSCH communication connection recording unit 114 can be realized by a volatile memory or a non-volatile memory.

[0043] FIG. 5 is a block diagram schematically showing the configuration of remote terminal 130 in the first embodiment. The remote terminal 130 includes a communication unit 131, a ProSe communication data processing unit 132, a ProSe communication connection control unit 133, a PSSCH communication connection recording unit 134, and an ETWS information processing unit 135.

[0044] The communication unit 131 communicates with the base station 101 and the relay terminal 110. In this case, the remote terminal 130 is located outside the range of the radio waves from the base station 101, and therefore the communication unit 131 cannot communicate with the base station 101 and communicates with the relay terminal 110. For example, the communication unit 131 transmits messages in the data plane and the control plane on a communication channel used by ProSe.

[0045] The ProSe communication data processing unit 132 processes a communication protocol for transmitting messages between the data plane and the control plane on a communication channel used by ProSe. For example, the ProSe communication data processing unit 132 passes an ETWS notification message received on the PSSCH to the ETWS information processing unit 135, and passes necessary data (e.g., control plane messages) received on the communication channel used by ProSe to the ProSe communication connection control unit 133.

[0046] The ProSe communication connection control unit 133 processes communication messages of the control plane, such as connection establishment and release, that are necessary for communication on a communication channel used by ProSe.

[0047] The PSSCH communication connection recording unit 134 records information about the relay terminal 110 to which the remote terminal 130 is currently connected as a result of the control plane processing for establishing and releasing a connection performed by the ProSe communication connection control unit 133.

[0048] The ETWS information processing unit 135 processes the ETWS notification message received from the ProSe communication data processing unit 132.

[0049] Part or all of the ProSe communication data processing unit 132, ProSe communication connection control unit 133, and ETWS information processing unit 135 described above can be configured, for example, as shown in FIG. 4(A), by a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided over a network or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product. In other words, the remote terminal 130 can be realized by a computer.

[0050] In addition, some or all of the ProSe communication data processing unit 132, the ProSe communication connection control unit 133, and the ETWS information processing unit 135 can also be configured as a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC, or an FPGA, as shown in Figure 4(B). As described above, the ProSe communication data processing unit 132, the ProSe communication connection control unit 133, and the ETWS information processing unit 135 can be realized by a processing circuit network.

[0051] Furthermore, the communication unit 131 can be realized by a wireless communication device having a wireless communication function. The PSSCH communication connection recording unit 134 can be realized by a volatile memory or a non-volatile memory.

[0052] FIG. 6 is a sequence diagram showing a communication procedure of ETWS information in the first embodiment. First, some trigger causes the remote terminal 130 and the relay terminal 110 to establish a connection for one-to-one communication using the PSSCH (S20).

[0053] Specifically, in remote terminal 130, ProSe communication connection control unit 133 uses ProSe communication data processing unit 132 and communication unit 131 to transmit and receive control messages for establishing a connection for one-to-one communication using PSSCH to and from relay terminal 110. In relay terminal 110, ProSe communication connection control unit 113 uses ProSe communication data processing unit 112 and communication unit 111 to transmit and receive control messages for establishing a connection for one-to-one communication using PSSCH to and from remote terminal 130.

[0054] Then, when the exchange of control messages according to the protocol for establishing the connection is completed, ProSe communication connection control unit 133 of remote terminal 130 records information about the connection with relay terminal 110 in PSSCH communication connection recording unit 134. Also, ProSe communication connection control unit 113 of relay terminal 110 records information about the connection with remote terminal 130 in PSSCH communication connection recording unit 114.

[0055] Next, the base station 101 transmits a short message indicating the presence of ETWS information to the relay terminal 110 on the PDCCH (S21). In this way, the base station 101 notifies the relay terminal 110 that the ETWS information exists.

[0056] Here, the communication unit 111 of the relay terminal 110 receives the short message, and the ETWS processing unit 115 recognizes that the ETWS information is to be notified.

[0057] The relay terminal 110, which has received the short message indicating the presence of ETWS information, receives SIB1 transmitted on the BCCH in order to receive information indicating the transmission timing of the ETWS information (S22).

[0058] For example, the communication unit 111 of the relay terminal 110 receives SIB1 transmitted on the BCCH to receive information indicating the transmission timing of the ETWS information. The received SIB1 is then provided to the ETWS processing unit 115. This allows the ETWS processing unit 115 to know the transmission timing on the BCCH of SIB6 and SIB7 indicating the ETWS information from the contents of the received SIB1.

[0059] Based on the transmission timing of SIB6 on the BCCH found in step S22, relay terminal 110 receives SIB6 on the BCCH (S23). For example, at the transmission timing of SIB6 on the BCCH found in step S22, ETWS processing unit 115 causes communication unit 111 to receive SIB6 on the BCCH and acquires the SIB6.

[0060] The relay terminal 110 transmits an ETWS notification message including the contents of the received SIB6 to the remote terminal 130 using a connection for one-to-one communication using the PSSCH (S24).

[0061] For example, the ETWS processing unit 115 passes the contents of SIB6 received in step S23 to the ETWS information transfer processing unit 116. The ETWS information transfer processing unit 116 generates an ETWS notification message including the contents of the passed SIB6, and causes the ProSe communication data processing unit 112 and the communication unit 111 to transmit the ETWS notification message to the remote terminal 130 with which a connection for one-to-one communication using PSSCH has been established in step S20. Specifically, the ETWS information transfer processing unit 116 reads out information about the connected remote terminal 130 recorded in the PSSCH communication connection recording unit 114, passes an ETWS notification message to the ProSe communication data processing unit 112, and requests transmission to the remote terminal 130 on the PSSCH.

[0062] The remote terminal 130 then acquires the ETWS information from the contents of SIB6 included in the received ETWS notification message. Specifically, the ETWS information processing unit 135 processes the contents of SIB6 included in the received ETWS notification message as earthquake and tsunami warning information.

[0063] Furthermore, based on the transmission timing of SIB7 on the BCCH known in step S22, relay terminal 110 receives SIB7 on the BCCH (S25). For example, at the transmission timing of SIB7 on the BCCH known in step S22, ETWS processing unit 115 causes communication unit 111 to receive SIB7 on the BCCH and acquires the SIB7.

[0064] The relay terminal 110 transmits an ETWS notification message including the contents of the received SIB7 to the remote terminal 130 using a connection for one-to-one communication using the PSSCH (S26).

[0065] For example, the ETWS processing unit 115 passes the contents of SIB7 received in step S25 to the ETWS information transfer processing unit 116. The ETWS information transfer processing unit 116 generates an ETWS notification message including the contents of the passed SIB7, and causes the ProSe communication data processing unit 112 and the communication unit 111 to transmit the ETWS notification message to the remote terminal 130 with which a connection for one-to-one communication using PSSCH has been established in step S20. Specifically, the ETWS information transfer processing unit 116 reads out information about the connected remote terminal 130 recorded in the PSSCH communication connection recording unit 114, passes an ETWS notification message to the ProSe communication data processing unit 112, and requests transmission to the remote terminal 130 on the PSSCH.

[0066] The remote terminal 130 then acquires the ETWS information from the contents of SIB7 included in the received ETWS notification message. Specifically, the ETWS information processing unit 135 processes the contents of SIB7 included in the received ETWS notification message as earthquake and tsunami warning information.

[0067] As a result, even if base station 101, relay terminal 110, and remote terminal 130 do not support the UE-to-Network Relay method, ETWS information can be transmitted to remote terminal 130.

[0068] Furthermore, by combining the above-described embodiment 1 with the method described in Patent Document 1 or the method described in the following document, it becomes possible for the relay terminal 110 to transmit ETWS information to the remote terminal 130 using multiple communication methods. Transactions of Information Processing Society of Japan, Vol. 60, No. 2, 514-526 (February 2019)

[0069] Embodiment 2 As shown in FIG. 1, a wireless communication system 200 according to the second embodiment includes a relay terminal 210 and a remote terminal 230. In the second embodiment, when relay terminal 210 is located within range 102 of radio waves from base station 101 and remote terminal 230 is located outside range 102 of radio waves from base station 101, upon receiving emergency alert information from base station 101, which is information for notifying of an emergency situation, relay terminal 210 transmits a broadcast message including the emergency alert information to remote terminal 230 using PSSCH. Here, when relay terminal 210 is to transmit system information to remote terminal 230, it transmits a broadcast message containing emergency alert information at a timing different from the timing of transmitting the system information.

[0070] FIG. 7 is a block diagram schematically showing the configuration of relay terminal 210 in the second embodiment. The relay terminal 210 includes a communication unit 111, a ProSe communication data processing unit 112, an ETWS processing unit 115, and a Discovery transmission unit 217.

[0071] The communication unit 111, ProSe communication data processing unit 112, and ETWS processing unit 115 of the relay terminal 210 in the second embodiment are the same as the communication unit 111, ProSe communication data processing unit 112, and ETWS processing unit 115 of the relay terminal 110 in the first embodiment. However, when the ProSe communication data processing unit 112 in the second embodiment receives a request to send a Discovery message from the Discovery transmission unit 217, it causes the communication unit 111 to transmit the Discovery message to the remote terminal 230. Also, the ETWS processing unit 115 in the second embodiment passes the ETWS information received by the communication unit 111 to the Discovery transmission unit 217.

[0072] The Discovery transmission unit 217 transmits a Discovery message at an autonomously determined timing via the ProSe communication data processing unit 112 and the communication unit 111. For example, after receiving ETWS information from the ETWS processing unit 115, the Discovery transmission unit 217 generates a Discovery message including ETWS information as the first Discovery message to be transmitted, and otherwise generates a Discovery message not including ETWS information and requests the ProSe communication data processing unit 112 to transmit that Discovery message.

[0073] Here, the ProSe communication data processing unit 112, the ETWS processing unit 115, and the Discovery transmission unit 217 are also referred to as a control unit 219. When emergency alert information is received, if there is a remote terminal 230 that can communicate with the relay terminal 210 via ProSe outside the range 102 reached by radio waves from the base station 101, the control unit 219 causes the communication unit 111 to transmit a broadcast message including the emergency alert information to the remote terminal 230 using PSSCH.

[0074] A part or all of the above-described Discovery transmission unit 217 can be configured, for example, as shown in FIG. 4(A), by a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided via a network, or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product. In other words, the relay terminal 210 can be realized by a computer.

[0075] In addition, part or all of the discovery transmission unit 217 can also be configured with a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC, or an FPGA, as shown in Figure 4(B). As described above, the discovery transmission unit 217 can be realized by a processing circuit network.

[0076] FIG. 8 is a block diagram showing a schematic configuration of remote terminal 230 according to the second embodiment. The remote terminal 230 includes a communication unit 131, a ProSe communication data processing unit 132, an ETWS information processing unit 135, and a Discovery receiving unit 236.

[0077] The communication unit 131, ProSe communication data processing unit 132, and ETWS information processing unit 135 of the remote terminal 230 in the second embodiment are the same as the communication unit 131, ProSe communication data processing unit 132, and ETWS information processing unit 135 of the remote terminal 130 in the first embodiment. However, the ProSe communication data processing unit 132 in the second embodiment passes the Discovery message received by the communication unit 131 to the Discovery receiving unit 236. Also, the ETWS information processing unit 135 in the second embodiment processes the ETWS information passed from the Discovery receiving unit 236 as earthquake and tsunami warning information.

[0078] The Discovery receiving unit 236 processes a Discovery message passed from the ProSe communication data processing unit 132. For example, if ETWS information is included in the Discovery message, the Discovery receiving unit 236 passes the ETWS information to the ETWS information processing unit 135.

[0079] A part or all of the above-described Discovery receiving unit 236 can be configured, for example, as shown in FIG. 4(A), by a memory 10 and a processor 11 such as a CPU that executes a program stored in the memory 10. Such a program may be provided over a network or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product. In other words, the remote terminal 230 can be realized by a computer.

[0080] The discovery receiving unit 236 can also be configured, for example, as shown in FIG. 4(B), with a processing circuit 12 such as a single circuit, a composite circuit, a processor operated by a program, a parallel processor operated by a program, an ASIC, or an FPGA. As described above, the discovery receiving unit 236 can be realized by a processing circuit network.

[0081] FIG. 9 is a sequence diagram showing a communication procedure of ETWS information in the second embodiment. First, base station 101 transmits a short message indicating the presence of ETWS information to relay terminal 210 on the PDCCH (S30). In this way, base station 101 notifies relay terminal 210 that ETWS information exists.

[0082] The relay terminal 210, which has received the short message indicating the presence of ETWS information, receives SIB1 transmitted on the BCCH in order to receive information indicating the transmission timing of the ETWS information (S31).

[0083] Based on the transmission timing of SIB6 on the BCCH known in step S31, relay terminal 210 receives SIB6 on the BCCH (S32).

[0084] The relay terminal 210 transmits a Discovery message including the content of the received SIB6 to the remote terminal 230 (S33).

[0085] For example, the ETWS processing unit 115 passes the content of SIB6 received in step S32 to the Discovery transmission unit 217. The Discovery transmission unit 217 transmits a Discovery message at timing that is determined autonomously. Here, after the content of SIB6 is passed to the Discovery transmission unit 217, the Discovery transmission unit 217 generates a Discovery message by including the content of SIB6 in the Discovery message that is to be transmitted first. Then, the Discovery transmission unit 217 requests the ProSe communication data processing unit 112 to transmit the generated Discovery message. In cases other than those described above, the Discovery transmission unit 217 generates a Discovery message that does not include ETWS information and requests the ProSe communication data processing unit 112 to transmit the generated Discovery message. Then, the ProSe communication data processing unit 112 causes the communication unit 111 to transmit the Discovery message.

[0086] Then, the remote terminal 230 acquires the ETWS information from the contents of SIB6 included in the received Discovery message. For example, when the communication unit 131 receives a Discovery message, the ProSe communication data processing unit 132 of the remote terminal 230 passes the Discovery message to the Discovery receiving unit 236. If the passed Discovery message includes SIB6, the Discovery receiving unit 236 passes the contents of SIB6 to the ETWS information processing unit 135. The ETWS information processing unit 135 processes the passed contents of SIB6 as earthquake and tsunami warning information.

[0087] Based on the transmission timing of SIB7 on the BCCH obtained in step S31, relay terminal 210 receives SIB7 on the BCCH (S34).

[0088] The relay terminal 210 transmits a Discovery message including the content of the received SIB7 to the remote terminal 230 (S35).

[0089] For example, the ETWS processing unit 115 passes the contents of SIB7 received in step S34 to the Discovery transmission unit 217. After receiving the contents of SIB7, the Discovery transmission unit 217 generates a Discovery message by including the contents of SIB7 in the Discovery message to be transmitted first. Then, the Discovery transmission unit 217 requests the ProSe communication data processing unit 112 to transmit the generated Discovery message. Then, the ProSe communication data processing unit 112 causes the communication unit 111 to transmit the Discovery message.

[0090] Then, the remote terminal 230 acquires the ETWS information from the contents of SIB7 included in the received Discovery message. For example, when the communication unit 131 receives a Discovery message, the ProSe communication data processing unit 132 of the remote terminal 230 passes the Discovery message to the Discovery receiving unit 236. If the passed Discovery message includes SIB7, the Discovery receiving unit 236 passes the contents of SIB7 to the ETWS information processing unit 135. The ETWS information processing unit 135 processes the passed contents of SIB7 as earthquake and tsunami warning information.

[0091] As a result, even if the base station 101, the relay terminal 210, and the remote terminal 230 do not support the UE-to-Network Relay method, it is possible to transmit the ETWS information to the remote terminal 230.

[0092] Furthermore, by combining the above-described first embodiment with the method described in Patent Document 1 or the method described in the document described in the above-described first embodiment, it becomes possible for the relay terminal 210 to transmit ETWS information to the remote terminal 230 using multiple communication methods.

[0093] In the second embodiment described above, a Discovery message is used, but a message other than a Discovery message may be used as long as it is a broadcast message that can be received by a remote terminal 230 that has not yet established a connection for one-to-one communication with relay terminal 210 using PSSCH.

[0094] Embodiment 3 As shown in FIG. 1, a wireless communication system 300 according to the third embodiment includes a relay terminal 310 and a remote terminal 330. In embodiment 3, when relay terminal 310 is located within range 102 of radio waves from base station 101 and remote terminal 330 is located outside range 102 of radio waves from base station 101, upon receiving emergency alert information from base station 101, which is information for notifying of an emergency situation, relay terminal 310 transmits the emergency alert information to remote terminal 330 using the connection established with remote terminal 330 for one-to-one communication using PSSCH, and also transmits a broadcast message including the emergency alert information to remote terminal 330 using PSSCH. Here, it is assumed that relay terminal 310 establishes a connection with remote terminal 330 before receiving the emergency alert information. In addition, when relay terminal 310 is to transmit system information to remote terminal 330, it establishes a connection with remote terminal 330 at a timing different from the timing of transmitting the system information, and transmits a broadcast message including emergency alert information.

[0095] FIG. 10 is a block diagram schematically showing the configuration of relay terminal 310 in the third embodiment. The relay terminal 310 includes a communication unit 111, a ProSe communication data processing unit 312, a ProSe communication connection control unit 113, a PSSCH communication connection recording unit 114, an ETWS processing unit 315, an ETWS information transfer processing unit 116, and a Discovery transmission unit 217.

[0096] The communication unit 111, ProSe communication connection control unit 113, PSSCH communication connection recording unit 114, and ETWS information transfer processing unit 116 of the relay terminal 310 in embodiment 3 are the same as the communication unit 111, ProSe communication connection control unit 113, PSSCH communication connection recording unit 114, and ETWS information transfer processing unit 116 of the relay terminal 110 in embodiment 1. Furthermore, the discovery transmission unit 217 of the relay terminal 310 in the third embodiment is the same as the discovery transmission unit 217 of the relay terminal 210 in the second embodiment.

[0097] The ProSe communication data processing unit 312 processes the communication protocol for transmitting messages between the data plane and the control plane on the communication channel used by ProSe. The ProSe communication data processing unit 312 passes necessary data (e.g., control plane messages) received by the communication unit 111 on the communication channel used by ProSe to the ProSe communication connection control unit 113. Furthermore, upon receiving a request to send a Discovery message from the Discovery transmission unit 217 , the ProSe communication data processing unit 312 causes the communication unit 111 to transmit the Discovery message to the remote terminal 330 .

[0098] The ETWS processing unit 315 passes the ETWS information received by the communication unit 111 to the ETWS information transfer processing unit 116 and the Discovery transmission unit 217.

[0099] Here, the ProSe communication data processing unit 312, the ProSe communication connection control unit 113, the ETWS processing unit 315, the ETWS information transfer processing unit 116, and the Discovery transmission unit 217 are also referred to as a control unit 319. When emergency alert information is received, if there is a remote terminal 330 that can communicate with the relay terminal 310 via ProSe outside the range 102 reached by radio waves from the base station 101, the control unit 319 causes the communication unit 111 to transmit the emergency alert information to the remote terminal 330 using the connection established with the remote terminal 330 for one-to-one communication using PSSCH, and also causes the communication unit 111 to transmit a broadcast message including the emergency alert information to the remote terminal 330 using PSSCH.

[0100] FIG. 11 is a block diagram showing a schematic configuration of remote terminal 330 according to the third embodiment. The remote terminal 330 includes a communication unit 131, a ProSe communication data processing unit 332, a ProSe communication connection control unit 133, a PSSCH communication connection recording unit 134, an ETWS information processing unit 335, and a Discovery receiving unit 236.

[0101] The communication unit 131, ProSe communication connection control unit 133, and PSSCH communication connection recording unit 134 of the remote terminal 330 in embodiment 3 are the same as the communication unit 131, ProSe communication connection control unit 133, and PSSCH communication connection recording unit 134 of the remote terminal 130 in embodiment 1. Furthermore, the discovery receiving unit 236 of the remote terminal 330 in the third embodiment is the same as the discovery receiving unit 236 of the remote terminal 230 in the second embodiment.

[0102] The ProSe communication data processing unit 332 processes a communication protocol for transmitting messages between the data plane and the control plane on a communication channel used by ProSe. For example, the ProSe communication data processing unit 332 passes an ETWS notification message received on the PSSCH to the ETWS information processing unit 335, and passes necessary data (e.g., control plane messages) received on the communication channel used by ProSe to the ProSe communication connection control unit 133. In addition, the ProSe communication data processing unit 332 passes the Discovery message received by the communication unit 131 to the Discovery receiving unit 236.

[0103] The ETWS information processing unit 335 processes the ETWS notification message received from the ProSe communication data processing unit 332. For example, the ETWS information processing unit 335 processes the ETWS information included in the received ETWS notification message as earthquake and tsunami warning information. In addition, the ETWS information processing unit 335 processes the ETWS information passed from the Discovery receiving unit 236 as earthquake and tsunami warning information.

[0104] FIG. 12 is a sequence diagram showing a communication procedure of ETWS information in the third embodiment. First, some trigger causes the remote terminal 330 and the relay terminal 310 to establish a connection for one-to-one communication using PSSCH (S40).

[0105] Next, the base station 101 transmits a short message indicating the presence of ETWS information to the relay terminal 310 on the PDCCH (S41). In this way, the base station 101 notifies the relay terminal 310 that the ETWS information exists.

[0106] The relay terminal 310, which has received the short message indicating the presence of ETWS information, receives SIB1 transmitted on the BCCH in order to receive information indicating the transmission timing of the ETWS information (S42).

[0107] Based on the transmission timing of SIB6 on the BCCH obtained in step S22, relay terminal 310 receives SIB6 on the BCCH (S43).

[0108] The relay terminal 310 transmits an ETWS notification message including the contents of the received SIB6 to the remote terminal 330 using a connection for one-to-one communication using the PSSCH (S44).

[0109] For example, the ETWS processing unit 315 passes the contents of SIB6 received in step S43 to the ETWS information transfer processing unit 116. The ETWS information transfer processing unit 116 generates an ETWS notification message including the contents of the passed SIB6, and causes the ProSe communication data processing unit 312 and the communication unit 111 to transmit the ETWS notification message to the remote terminal 330 with which a connection for one-to-one communication using PSSCH has been established in step S40. Specifically, the ETWS information transfer processing unit 116 reads out information about the connected remote terminal 330 recorded in the PSSCH communication connection recording unit 114, passes an ETWS notification message to the ProSe communication data processing unit 312, and requests transmission to the remote terminal 330 on the PSSCH.

[0110] The remote terminal 330 then acquires the ETWS information from the contents of SIB6 included in the received ETWS notification message. Specifically, the ETWS information processing unit 335 processes the contents of SIB6 included in the received ETWS notification message as earthquake and tsunami warning information.

[0111] Furthermore, the relay terminal 310 transmits a Discovery message including the content of the received SIB6 to the remote terminal 330 (S45).

[0112] For example, the ETWS processing unit 315 passes the contents of SIB6 received in step S43 to the Discovery transmission unit 217. After receiving the contents of SIB6, the Discovery transmission unit 217 generates a Discovery message by including the contents of SIB6 in the Discovery message to be transmitted first. Then, the Discovery transmission unit 217 requests the ProSe communication data processing unit 312 to transmit the generated Discovery message. The ProSe communication data processing unit 312 causes the communication unit 111 to transmit the Discovery message.

[0113] Then, the remote terminal 330 acquires the ETWS information from the contents of SIB6 included in the received Discovery message. For example, when the communication unit 131 receives a Discovery message, the ProSe communication data processing unit 332 of the remote terminal 330 passes the Discovery message to the Discovery receiving unit 236. If the passed Discovery message includes SIB6, the Discovery receiving unit 236 passes the contents of SIB6 to the ETWS information processing unit 335. The ETWS information processing unit 335 processes the passed contents of SIB6 as earthquake and tsunami warning information.

[0114] Furthermore, based on the transmission timing of SIB7 on the BCCH known in step S42, relay terminal 310 receives SIB7 on the BCCH (S46). For example, at the transmission timing of SIB7 on the BCCH known in step S42, ETWS processing unit 315 causes communication unit 111 to receive SIB7 on the BCCH and acquires the SIB7.

[0115] The relay terminal 310 transmits an ETWS notification message including the received contents of SIB7 to the remote terminal 330 using a connection for one-to-one communication using PSSCH (S47). The processing here is the same as when the contents of SIB6 are received.

[0116] The remote terminal 330 then acquires the ETWS information from the contents of SIB7 included in the received ETWS notification message. Specifically, the ETWS information processing unit 135 processes the contents of SIB7 included in the received ETWS notification message as earthquake and tsunami warning information.

[0117] Furthermore, relay terminal 310 transmits a Discovery message including the received contents of SIB7 to remote terminal 330 (S48). The processing here is the same as when the contents of SIB6 are received.

[0118] Then, the remote terminal 330 obtains the ETWS information from the contents of SIB7 included in the received Discovery message.

[0119] As a result, even if the base station 101, the relay terminal 310, and the remote terminal 330 do not support the UE-to-Network Relay method, it is possible to transmit ETWS information to the remote terminal 330. Furthermore, as a result of the above, the relay terminal 310 can transmit ETWS information to the remote terminal 330 using a plurality of communication methods.

[0120] Embodiment 4 As shown in FIG. 1, a wireless communication system 400 according to the fourth embodiment includes a relay terminal 410 and a remote terminal 230. Remote terminal 230 in wireless communication system 400 according to the fourth embodiment is similar to remote terminal 230 in wireless communication system 200 according to the second embodiment. In the fourth embodiment, when relay terminal 410 receives emergency alert information, it determines a deadline for transmitting the emergency alert information, and transmits a broadcast message including the emergency alert information to remote terminal 230 multiple times within the deadline.

[0121] FIG. 13 is a block diagram schematically showing the configuration of relay terminal 410 in the fourth embodiment. The relay terminal 410 includes a communication unit 111, a ProSe communication data processing unit 112, an ETWS processing unit 415, a Discovery transmission unit 417, and an ETWS information storage unit 418.

[0122] The communication unit 111 and the ProSe communication data processing unit 112 of the relay terminal 410 in the fourth embodiment are the same as the communication unit 111 and the ProSe communication data processing unit 112 of the relay terminal 110 in the first embodiment. However, when ProSe communication data processing unit 112 in the fourth embodiment receives a request to transmit a Discovery message from Discovery transmission unit 417, it causes communication unit 111 to transmit the Discovery message to remote terminal 230.

[0123] The ETWS processing unit 415 receives the ETWS information received by the communication unit 111 and determines the transmission end time, which is the time to end transmission of the ETWS information. Then, the ETWS processing unit 415 associates the ETWS information with the transmission end time and stores them in the ETWS information storage unit 418. The transmission end time is the deadline for transmitting the ETWS information.

[0124] The ETWS information storage unit 418 records the ETWS information provided by the ETWS processing unit 415 in association with the transmission end time. FIG. 14 is a schematic diagram showing an example of the ETWS information and transmission end time stored in the ETWS information storage unit 418.

[0125] 13, the Discovery transmission unit 417 transmits a Discovery message via the ProSe communication data processing unit 112 and the communication unit 111 at autonomously determined timing. Here, when the Discovery transmission unit 417 transmits the Discovery message, if the transmission end time has not passed, in other words, if ETWS information whose transmission end time is later than the current time is stored in the ETWS information storage unit 418, the Discovery transmission unit 417 generates a Discovery message including such ETWS information. Note that if such ETWS information is not stored in the ETWS information storage unit 418, the Discovery transmission unit 417 generates a Discovery message that does not include ETWS information. Then, the Discovery transmission unit 417 requests the ProSe communication data processing unit 112 to transmit the generated Discovery message.

[0126] Here, the ProSe communication data processing unit 112, the ETWS processing unit 415, and the Discovery transmission unit 417 are also referred to as a control unit 419. When the communication unit 111 receives emergency alert information, the control unit 419 determines a deadline for transmitting the emergency alert information and causes the communication unit 111 to transmit a broadcast message including the emergency alert information to the remote terminal 230 multiple times within that deadline.

[0127] The ETWS information storage unit 418 described above can be realized by a volatile or non-volatile memory.

[0128] The sequence showing the ETWS information communication procedure in the fourth embodiment is almost the same as the sequence showing the ETWS information communication procedure in the second embodiment shown in FIG. However, when the communication unit 111 receives SIB6 on the BCCH in step S32 of Fig. 9, the ETWS processing unit 415 receives the contents of SIB6 and stores the contents as ETWS information in the ETWS information storage unit 418. Then, the ETWS processing unit 415 determines the transmission end time of the ETWS information and stores the transmission end time in association with the ETWS information in the ETWS information storage unit 418. The transmission end time can be set to, for example, the current time plus a predetermined time. Note that the transmission end time may also be determined by other methods, such as using a timer notified by the base station 101.

[0129] Then, in step S33, when autonomously transmitting a Discovery message, the Discovery transmission unit 417 checks the transmission end time stored in the ETWS information storage unit 418, and if there is ETWS information whose transmission end time is later than the current time, it generates a Discovery message including that ETWS information, and if there is no such ETWS information, it generates a Discovery message that does not include the ETWS information and requests the ProSe communication data processing unit 112 to transmit the generated Discovery message. In response to such a request, the ProSe communication data processing unit 112 transmits the Discovery message.

[0130] In steps S34 and S35 in FIG. 9, the same processing as above is performed on SIB7.

[0131] As a result, for a certain period of time after the relay terminal 410 receives the ETWS information, the relay terminal 410 can transmit the ETWS information to the remote terminal 430 in a Discovery message. This increases the likelihood that the remote terminal 430 will receive the ETWS information.

[0132] Embodiment 5. As shown in FIG. 1, a wireless communication system 500 according to the fifth embodiment includes a relay terminal 510 and a remote terminal 130. Remote terminal 130 in wireless communication system 500 according to the fifth embodiment is similar to remote terminal 130 in wireless communication system 100 according to the first embodiment. In the fifth embodiment, upon receiving emergency alert information, relay terminal 510 determines a time limit for transmitting the emergency alert information, and transmits the emergency alert information to remote terminal 130 multiple times within the time limit.

[0133] FIG. 15 is a block diagram schematically showing a configuration of relay terminal 510 in the fifth embodiment. The relay terminal 510 includes a communication unit 111, a ProSe communication data processing unit 112, a ProSe communication connection control unit 113, a PSSCH communication connection recording unit 114, an ETWS processing unit 515, an ETWS information transfer processing unit 516, and an ETWS information storage unit 518.

[0134] The communication unit 111, ProSe communication data processing unit 112, ProSe communication connection control unit 113, and PSSCH communication connection recording unit 114 of the relay terminal 510 in embodiment 5 are the same as the communication unit 111, ProSe communication data processing unit 112, ProSe communication connection control unit 113, and PSSCH communication connection recording unit 114 of the relay terminal 110 in embodiment 1.

[0135] The ETWS processing unit 515 receives the ETWS information received by the communication unit 111 and determines the transmission end time, which is the time to end the transmission of the ETWS information. The ETWS processing unit 515 then provides the ETWS information to the ETWS information transfer processing unit 516 and stores the ETWS information and the transmission end time in the ETWS information storage unit 518 in association with each other.

[0136] The ETWS information storage unit 518 associates and records the ETWS information and the transmission end time provided from the ETWS processing unit 515. The information stored here is the same as that in the fourth embodiment, for example, as shown in FIG.

[0137] Upon receiving ETWS information from the ETWS processing unit 515, or upon an autonomously determined timing, the ETWS information transfer processing unit 516 requests the ProSe communication data processing unit 112 to transmit an ETWS notification message including ETWS information on the PSSCH to the remote terminal 130 with which a connection for one-to-one communication using the PSSCH has been established, based on the information recorded in the PSSCH communication connection recording unit 114.

[0138] The ProSe communication data processing unit 112, the ProSe communication connection control unit 113, the ETWS processing unit 515, and the ETWS information transfer processing unit 516 are also referred to as a control unit 519. When communication unit 111 receives emergency alert information, control unit 519 determines a deadline for transmitting the emergency alert information and causes communication unit 111 to transmit the emergency alert information to remote terminal 130 multiple times within the deadline.

[0139] The sequence showing the ETWS information communication procedure in the fifth embodiment is almost the same as the sequence showing the ETWS information communication procedure in the first embodiment shown in FIG. 6, when the communication unit 111 receives SIB6 on the BCCH, the ETWS processing unit 515 receives the contents of SIB6 and stores the contents as ETWS information in the ETWS information storage unit 518. Then, the ETWS processing unit 515 determines the transmission end time of the ETWS information and stores the transmission end time in association with the ETWS information in the ETWS information storage unit 518. The transmission end time may be determined in the same manner as in the fourth embodiment.

[0140] Then, the ETWS processing unit 515 passes the contents of SIB6 received in step S23 to the ETWS information transfer processing unit 516. The ETWS information transfer processing unit 516 generates an ETWS notification message including the contents of the passed SIB6, and causes the ProSe communication data processing unit 112 and the communication unit 111 to transmit the ETWS notification message to the remote terminal 130, with which a connection for one-to-one communication using PSSCH has been established in step S20, using the connection for one-to-one communication using PSSCH. The processing here is the same as in embodiment 1.

[0141] Furthermore, the ETWS information transfer processing unit 516, at an autonomously determined timing, checks the transmission end time stored in the ETWS information storage unit 518, and if there is ETWS information whose transmission end time is later than the current time, generates an ETWS notification message including that ETWS information, and causes the ProSe communication data processing unit 112 and the communication unit 111 to transmit the ETWS notification message to the remote terminal 130 with which a connection for one-to-one communication using PSSCH has been established in step S20. Note that if such ETWS information does not exist at an autonomous timing, the ETWS processing unit 515 does not cause the ETWS notification message to be transmitted.

[0142] In addition, in steps S25 and S26 in FIG. 6, the same processing as above is performed on SIB7.

[0143] As a result, for a certain period of time after the relay terminal 510 receives the ETWS information, the relay terminal 510 can transmit the ETWS information to the remote terminal 130 in an ETWS notification message. This increases the likelihood that the remote terminal 130 will receive the ETWS information.

[0144] Embodiment 6 As shown in FIG. 1, a wireless communication system 600 according to the sixth embodiment includes a relay terminal 610 and a remote terminal 130. Remote terminal 130 in wireless communication system 600 according to the fifth embodiment is the same as remote terminal 130 in wireless communication system 100 according to the first embodiment. In the sixth embodiment, when relay terminal 610 receives emergency alert information, it determines a time limit for transmitting the emergency alert information, and transmits the emergency alert information to remote terminal 130 multiple times within the time limit. In the sixth embodiment, when the relay terminal 610 receives emergency alert information, if the relay terminal 610 has not established a connection with the remote terminal 130, the relay terminal 610 establishes a connection with the remote terminal 130 again and then transmits the emergency alert information to the remote terminal 130.

[0145] FIG. 16 is a block diagram schematically showing a configuration of relay terminal 610 in the sixth embodiment. The relay terminal 610 includes a communication unit 111, a ProSe communication data processing unit 112, a ProSe communication connection control unit 613, a PSSCH communication connection recording unit 114, an ETWS processing unit 515, an ETWS information transfer processing unit 616, and an ETWS information storage unit 518.

[0146] The communication unit 111, ProSe communication data processing unit 112, and PSSCH communication connection recording unit 114 of the relay terminal 610 in embodiment 6 are the same as the communication unit 111, ProSe communication data processing unit 112, and PSSCH communication connection recording unit 114 of the relay terminal 110 in embodiment 1. Moreover, the ETWS processing unit 515 and the ETWS information storage unit 518 of the relay terminal 610 in the sixth embodiment are similar to the ETWS processing unit 515 and the ETWS information storage unit 518 of the relay terminal 510 in the fifth embodiment.

[0147] The ProSe communication connection control unit 613 processes control plane communication messages such as connection establishment and release necessary for communication on a communication channel used by ProSe. In the sixth embodiment, upon receiving a request from the ETWS information transfer processing unit 616, the ProSe communication connection control unit 613 establishes a connection for one-to-one communication with the remote terminal 130 using the PSSCH.

[0148] The ETWS information transfer processing unit 616, upon receiving ETWS information from the ETWS processing unit 515 or upon an autonomously determined timing, requests the ProSe communication data processing unit 112 to transmit an ETWS notification message including ETWS information on the PSSCH to the remote terminal 130 with which a connection for one-to-one communication using the PSSCH has been established, based on the information recorded in the PSSCH communication connection recording unit 114. In the sixth embodiment, when an ETWS notification message is transmitted, if a connection for one-to-one communication using PSSCH with the remote terminal 130 has not been established, the ETWS information transfer processing unit 616 requests the ProSe communication connection control unit 613 to establish a connection for one-to-one communication using PSSCH with the remote terminal 130. Whether a connection for one-to-one communication using PSSCH with the remote terminal 130 has been established can be determined by checking the information recorded in the PSSCH communication connection recording unit 114.

[0149] Here, the ProSe communication data processing unit 112, the ProSe communication connection control unit 613, the ETWS processing unit 515, and the ETWS information transfer processing unit 616 are also referred to as a control unit 619. When communication unit 111 receives emergency alert information, control unit 619 determines a deadline for transmitting the emergency alert information, and causes communication unit 111 to transmit the emergency alert information to remote terminal 130 multiple times within the deadline. If the communication unit 111 receives emergency alert information and a connection with the remote terminal 130 has not been established, the control unit 619 establishes a connection with the remote terminal 130 again, and then causes the communication unit 111 to transmit the emergency alert information to the remote terminal 130.

[0150] As a result, for a certain period of time after the relay terminal 610 receives the ETWS information, it becomes possible for the relay terminal 610 to establish a new connection for one-to-one communication using PSSCH with a remote terminal 130 with which a connection for one-to-one communication using PSSCH has not yet been established, and to transmit the ETWS information to the newly established remote terminal 130. This increases the likelihood that the remote terminal 130 will receive the ETWS information.

[0151] In addition, in embodiment 1 or embodiment 3, even if a connection with the remote terminal 130, 330 has not been established when the relay terminal 110, 310 receives emergency alert information, the ETWS information transfer processing unit 116 may instruct the ProSe communication connection control unit 113 to establish a connection with the remote terminal 130, 330.

[0152] In the above explanation, ETWS information has been used as an example of emergency alert information transmitted using a PWS. However, embodiments 1 to 6 can also be applied to other emergency alert information that can be transmitted using a PWS, such as the Commercial Mobile Alert System (CMAS), the Korean Public Alert System (KPAS), or EU-Alert. [Explanation of symbols]

[0153] 100,200,300,400,500,600 wireless communication system, 101 base station, 110,210,310,410,510,610 relay terminal, 111 communication unit, 112,312 ProSe communication data processing unit, 113,613 ProSe communication connection control unit, 114 PSSCH communication connection recording unit, 115,315,415,515 ETWS processing unit, 116,516,616 ETWS information transfer processing unit, 217,417 discovery transmission unit, 418,518 ETWS information storage unit, 119,219,319,419,519,619 control unit, 130,230,330 remote terminal, 131 communication unit, 132,332 ProSe communication data processing unit, 133 ProSe communication connection control unit, 134 PSSCH communication connection recording unit, 135,335 ETWS information processing unit, 236 Discovery receiving unit.

Claims

1. A communication system that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), A base station; a first mobile terminal; a second mobile terminal capable of communicating with the first mobile terminal using ProSe (Proximity-based Services); When the first mobile terminal is present within a range where radio waves from the base station reach, and the second mobile terminal is present outside the range where radio waves from the base station reach, the first mobile terminal, upon receiving emergency alert information from the base station, which is information for notifying an emergency situation, transmits a broadcast message including the emergency alert information to the second mobile terminal using a PSSCH (Physical Sidelink Shared Channel) separately from the timing of transmitting system information to the second mobile terminal. A communication system comprising:

2. Upon receiving the emergency alert information, the first mobile terminal determines a time limit for transmitting the emergency alert information, and transmits the broadcast message to the second mobile terminal a plurality of times within the time limit.

2. The communication system according to claim 1, wherein:

3. A communication system that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), A base station; a first mobile terminal; a second mobile terminal capable of communicating with the first mobile terminal using ProSe (Proximity-based Services); When the first mobile terminal is present within a range reached by radio waves from the base station and the second mobile terminal is present outside the range reached by radio waves from the base station, upon receiving emergency alert information from the base station, which is information for notifying the first mobile terminal of an emergency situation, the first mobile terminal transmits the emergency alert information to the second mobile terminal using a connection established with the second mobile terminal for one-to-one communication using a PSSCH (Physical Sidelink Shared CHannel), and also transmits a broadcast message including the emergency alert information to the second mobile terminal using the PSSCH. A communication system comprising:

4. The first mobile terminal establishes the connection before receiving the emergency alert information or after receiving the emergency alert information.

4. The communication system according to claim 3, wherein:

5. The first mobile terminal establishes the connection and transmits the broadcast message separately from the timing of transmitting system information to the second mobile terminal.

5. The communication system according to claim 3 or 4, wherein:

6. A mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), a communication unit that receives emergency alert information from a base station, the emergency alert information being information for informing the user of an emergency situation; and a control unit that, when the communication unit receives the emergency alert information, if another mobile terminal that can communicate with the mobile terminal via ProSe (Proximity-based Services) is present outside a range reached by radio waves from the base station, causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using a PSSCH (Physical Sidelink Shared Channel) separately from a timing of transmitting system information to the other mobile terminal. A mobile terminal characterized by:

7. A mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), a communication unit that receives emergency alert information from a base station, the emergency alert information being information for informing the user of an emergency situation; and a control unit that, when the communication unit receives the emergency alert information, if another mobile terminal that can communicate with the mobile terminal via ProSe (Proximity-based Services) is present outside a range reached by radio waves from the base station, causes the communication unit to transmit the emergency alert information to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using a PSSCH (Physical Sidelink Shared Channel), and causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using the PSSCH. A mobile terminal characterized by:

8. A computer that functions as a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), a communication unit that receives emergency alert information from a base station, the emergency alert information being information for informing the user of an emergency situation; When the communication unit receives the emergency alert information, if there is another mobile terminal that can communicate with the mobile terminal via ProSe (Proximity-based Services) outside a range reached by radio waves from the base station, the control unit causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using a PSSCH (Physical Sidelink Shared Channel) separately from the timing of transmitting system information to the other mobile terminal. A program characterized by.

9. A computer that functions as a mobile terminal that performs Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), a communication unit that receives emergency alert information from a base station, the emergency alert information being information for informing the user of an emergency situation; When the communication unit receives the emergency alert information, if another mobile terminal that can communicate with the mobile terminal via ProSe (Proximity-based Services) is present outside a range reached by radio waves from the base station, the control unit causes the communication unit to transmit the emergency alert information to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using a PSSCH (Physical Sidelink Shared Channel), and also functions as a control unit that causes the communication unit to transmit a broadcast message including the emergency alert information to the other mobile terminal using the PSSCH. A program characterized by.

10. A communication method performed by a mobile terminal performing Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), Receives emergency alert information from a base station, which is information to notify of an emergency situation, When the emergency alert information is received, if there is another mobile terminal that can communicate with the mobile terminal by ProSe (Proximity-based Services) outside the range of radio waves from the base station, a broadcast message including the emergency alert information is transmitted to the other mobile terminal using a PSSCH (Physical Sidelink Shared Channel) separately from the timing of transmitting system information to the other mobile terminal. A communication method characterized by:

11. A communication method performed by a mobile terminal performing Side Link Relay communication of 5G NR (Fifth Generation New Radio) defined by 3GPP (Third Generation Partnership Project), Receives emergency alert information from a base station, which is information to notify of an emergency situation, When the emergency alert information is received, if there is another mobile terminal that can communicate with the mobile terminal using ProSe (Proximity-based Services) outside a range reached by radio waves from the base station, the emergency alert information is transmitted to the other mobile terminal using a connection established with the other mobile terminal for one-to-one communication using a PSSCH (Physical Sidelink Shared CHannel), and a broadcast message including the emergency alert information is transmitted to the other mobile terminal using the PSSCH. A communication method characterized by:

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