Terminal and IMS access gateway

Abstract

This terminal comprises: a communication unit that performs voice communication in a first system; and a control unit that determines whether to continue the voice communication in a second system. The communication unit transmits, to a network node commonly used in both the first system and the second system, a first voice call setting change request message requesting resetting of the voice communication.

Description

Terminal and IMS Access Gateway

[0001] The present invention relates to a terminal and an IMS access gateway in a communication system.

[0002] 3GPP (Registered Trademark) (3rd Generation Partnership Project)'s 5GS (5G System) and 6GS (6G System) each have independent network functions (NFs: Network Function), and a method for continuing voice communication between these different systems is being studied.

[0003] 3GPP TS 23.502 V19.2.0(2025-01)3GPP TS 23.228 V19.1.0(2024-12)3GPP TS 23.334 V18.1.0(2024-06)

[0004] For example, when not using the UPF (User Plane Function) as a combo node, a change in the IP address may occur, making it difficult to continue the session of IMS voice communication. Thus, in the conventional specification, there is a possibility that voice communication may be interrupted during network migration.

[0005] The terminal in this embodiment includes a communication unit that performs voice communication in a first system, and a control unit that determines to continue the voice communication in a second system. The communication unit transmits a first voice call setting change request message requesting a reset of the voice communication to a network node commonly used in both the first system and the second system.

[0006] According to this embodiment, even when a movement occurs between 5GS and 6GS, IMS voice communication can be continued without interruption.

[0007] This is a diagram illustrating an example of a communication system. This is a diagram illustrating an example of a communication system in a roaming environment. This is a diagram illustrating an example of an IMS data channel network. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 1. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 1. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 1. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 2. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 2. This is a sequence diagram showing an example of the operation procedure of the communication system in Embodiment 2. This is a diagram showing an example of the functional configuration of a base station and network node in this embodiment. This is a diagram showing an example of the functional configuration of a terminal in this embodiment. This is a diagram showing an example of the hardware configuration of a base station, terminal and network node in this embodiment. This is a diagram showing an example of the configuration of a vehicle in this embodiment.

[0008] This embodiment will be described below with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention applies are not limited to those described below.

[0009] In the operation of the wireless communication system of this embodiment, existing technologies will be used as appropriate. Existing technologies include, for example, existing communication methods based on 3GPP standards such as NR (New Radio) (5G) / 5GC (5G Core network). However, existing technologies are not limited to NR / 5GC, but also include LTE, LTE-Advanced and NR (5G) and later methods, or wireless LAN (Local Area Network).

[0010] In this embodiment, "configuring" wireless parameters means that predetermined values ​​are set in advance, or that wireless parameters notified by the network node or terminal 20 are set.

[0011] Figure 1 is a diagram illustrating an example of a communication system. As shown in Figure 1, the communication system consists of a terminal 20 (UE) and multiple network nodes. Hereafter, one network node will be assigned to each function, but one network node may implement multiple functions, or multiple network nodes may implement one function. Also, the "connection" described below may be a logical connection or a physical connection.

[0012] The RAN (Radio Access Network) is a network node having wireless access functionality, which may include a base station 10, and is connected to the UE, AMF (Access and Mobility Management Function), and UPF (User plane function). The AMF is a network node having functions such as terminating the RAN interface, terminating the NAS (Non-Access Stratum), registration management, connection management, reachability management, and terminal mobility management. The UPF is a network node interconnected with the DN (Data Network) and having functions related to user plane data processing, such as PDU (Protocol Data Unit) session point to the outside, packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0013] AMF is connected to UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0014] SMF is a network node with functions such as session management, IP (Internet Protocol) address allocation and management for UEs, DHCP (Dynamic Host Configuration Protocol) functionality, ARP (Address Resolution Protocol) proxy, and roaming functionality. NEF is a network node with the function of notifying other NFs (Network Functions) of capabilities and events. NSSF is a network node with functions such as selecting the network slice to which the UE connects, determining the allowed NSSAI (Network Slice Selection Assistance Information), determining the NSSAI to be set, and determining the AMF set to which the UE connects. PCF is a network node with the function of controlling network policies. AF is a network node with the function of controlling application servers. NRF is a network node with the function of discovering NF instances that provide services. UDM is a network node that manages subscriber data and authentication data. UDM is connected to UDR (User Data Repository) which holds this data.

[0015] Figure 2 is a diagram illustrating an example of a communication system in a roaming environment. As shown in Figure 2, the network consists of a terminal 20 (UE) and multiple network nodes. Hereafter, one network node will be assigned to each function, however, one network node may implement multiple functions, or multiple network nodes may implement one function. Furthermore, the "connection" described below may be a logical connection or a physical connection.

[0016] The RAN is a network node with wireless access capabilities and is connected to the UE, AMF, and UPF. The AMF is a network node with functions such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node interconnected with the DN, acting as a PDU session point to the outside world, routing and forwarding packets, and handling QoS for the user plane. The UPF and DN constitute a network slice. In the wireless communication network of this embodiment, multiple network slices are constructed.

[0017] AMF is connected to UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

[0018] SMF is a network node with functions such as session management, IP address allocation and management for UEs, DHCP functionality, ARP proxy, and roaming functionality. NEF is a network node with the function of notifying other NFs of capabilities and events. NSSF is a network node with functions such as selecting the network slice to which a UE connects, determining which NSSAIs are allowed, determining which NSSAIs are configured, and determining which AMF set a UE connects to. PCF is a network node with the function of controlling network policies. AF is a network node with the function of controlling application servers. NRF is a network node with the function of discovering NF instances that provide services. SEPP is an opaque proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). vSEPP shown in Figure 2 is SEPP in the visited network, and hSEPP is SEPP in the home network.

[0019] As shown in Figure 2, the UE is in a roaming environment connected to the RAN and AMF in the Visited PLMN. The Visited PLMN and Home PLMN are connected via vSEPP and hSEPP. The UE can communicate with the UDM of the Home PLMN, for example, via the AMF of the Visited PLMN.

[0020] Figure 3 is a diagram illustrating an example of an IMS data channel network. As shown in Figure 3, the IMS data channel network consists of a terminal 20 (UE) and multiple network nodes in both the originating network and the terminating network. Hereafter, one network node will be assigned to each function, however, one network node may implement multiple functions, or multiple network nodes may implement one function. Also, the "connection" described below may be a logical connection or a physical connection. A network node may have the following functions, for example.

[0021] IMS-AGW (Access Gateway) is a network node that functions as a gateway between the UE and the IMS network, and also has functions related to voice communication access processing.

[0022] P-CSCF (Proxy-Call Session Control Function) is a network node that provides proxy functionality between the UE and IMS network, as well as access control functions for voice communications.

[0023] S-CSCF (Serving-Call Session Control Function) is a network node that has functions related to session control for the User Agent (UE).

[0024] An I-CSCF (Interrogate-Call Session Control Function) is a network node in an IMS network that serves as a connection point between networks (e.g., a caller and a caller) and has functions such as forwarding received SIP requests to its own network's S-CSCF.

[0025] The IMS AS (IP Multimedia Subsystem Application Server) is a network node in the IMS network that has functions such as communicating with the DCSF (Data Channel Signalling Function) for event notification, and receiving data channel control instructions from the DCSF and communicating with the MF (Movement Function). The IMS AS also receives registration requests for communication termination points from the DCSF, converts the received registration requests into SIP Registers, and sends them to the S-CSCF (Serving-Call Session Control Function). Furthermore, the IMS AS converts data channel establishment requests received from the DCSF into SIP INVITEs and sends them to the S-CSCF.

[0026] DCSF (Data Channel Signaling Function) is a network node that receives event reports from IMS-AS and has functions such as deciding whether or not to allow the provision of data channel services, managing bootstrap data channels, and HTTP web server functionality.

[0027] A Media Function (MF) in an IMS network is a network node that performs functions such as media resource management and data channel media traffic forwarding. The MF processes media between the Data Channel Application Server (DCAS), which is the communication termination point, and the destination termination point, based on configuration information received from the Data Channel Application Server (DCSF). The MF may also be called a Data Channel Media Function (DCMF). Furthermore, the MF may also be called a Multimedia Resource Function (MRF).

[0028] DCAS (Data Channel Application Server) is a network node in the IMS network that has functions such as being a communication termination point for media and signaling.

[0029] 3GPP's 5GS and 6GS, whose details will be further considered, each have independent network functions, but methods for maintaining voice communication between these different systems are being explored. For example, if a UPF (User Plane Function) is not used as a combo node, a change in IP address may occur, potentially making it difficult to continue IMS voice communication sessions. Thus, under the current specifications, voice communication may be interrupted during network migrations.

[0030] According to this embodiment, even if movement occurs between 5GS and 6GS, IMS voice communication can be continued without interruption. The following describes each embodiment of this design.

[0031] In this embodiment, 5GS is an example of the first system, and 6GS is an example of the second system. However, the first system and the second system may be any different system. For example, the first system may be 6GS, and the second system may be a successor to 6GS.

[0032] (Example 1) Example 1 shows a method for continuing IMS voice communication when migrating from 5GS to 6GS. In Example 1, UE 20 decides to migrate to 6GS and performs SIP renegotiation via P-CSCF 30F and IMS AGW 30G. Due to the system change, the P-CSCF buffers SIP messages and the IMS AGW temporarily stores the voice media to prevent communication interruption.

[0033] An example of the operation of the communication system of Embodiment 1 will be explained using Figures 4A-4D. Figure 4A-4D shows a series of operations, but this embodiment may be applied to some of the steps in the figure or to any combination of multiple steps.

[0034] In the example in Figure 4, an IMS voice call is in progress, and the 5GS (5G System) is providing service to UE 20. UE 20 has a PDU session held within the 6GS (6G System) and remembers the IP address for that PDU session.

[0035] In step S101 of Figure 4A, UE 20, which is communicating using 5GS, decides to move to 6GS. In this step, UE 20 decides to move to 6GS based on current network conditions or changes in QoS requirements.

[0036] In step S102, the UE 20 generates a SIP re-INVITE message and decides to send it. In this step, the UE 20 sends the SIP re-INVITE message to initiate session renegotiation in the IMS network.

[0037] In step S103, UE 20 sends a SIP re-INVITE (Reason header=IP-CAN change, SDP offer (c=UE IP address of 6GS PDU session)) to P-CSCF 30F. IP-CAN change may be an optional feature. In this step, UE 20 sends a SIP re-INVITE message with an SDP offer containing the IP address of the 6GS PDU session, along with a Reason header indicating an IP-CAN change. The SIP re-INVITE message is used by the IMS network to recognize network switching and allocate appropriate resources. SIP re-INVITE is an example of a first voice call configuration change request message. P-CSCF 30F is an example of a network node commonly used in both 5GS and 6GS. IP-CAN change is an example of information indicating that the network system accommodating voice communications is changing.

[0038] In step S104, if DL SIP messages exist based on the IP-CAN change, the P-CSCF 30F buffers the DL SIP messages. In this step, the P-CSCF 30F temporarily buffers the messages to prevent the loss of downlink SIP messages due to the IP-CAN change. This makes it possible to avoid session interruption.

[0039] In step S105, the P-CSCF 30F sends a message to the IMS AGW 30G: Configure AGW Connection Point (towards UE) (Remote Connection Address = UE IP address of 6GS PDU session). In this step, the P-CSCF 30F requests the IMS AGW 30G to configure a connection point using the UE IP address of the 6GS PDU session. This represents an initial setup to enable data communication on the new network.

[0040] In step S106, the IMS AGW 30G sends a Configure AGW Connection Point Ack to the P-CSCF 30F. In this step, the IMS AGW 30G responds to the connection configuration request from the P-CSCF 30F and sends a response message to confirm that the configuration is completed.

[0041] In step S107, the P-CSCF 30F sends a SIP re-INVITE to the IMS AS 30H.

[0042] In step S108, the IMS AS 30H sends a SIP 200 OK to the P-CSCF 30F.

[0043] In step S109, the P-CSCF 30F sends a SIP 200 OK to the UE 20.

[0044] These steps S107 - S109 represent the signaling exchange to complete the session update process within the IMS network, and notify the UE 20 that the session has been successfully reconfigured.

[0045] In step S110 of FIG. 4B, the IMS AGW 30G sends DL voice media to the 6G UPF 30E.

[0046] In this step, the IMS AGW 30G sends the voice media stream to the UPF (User Plane Function) of 6G, and starts the routing of voice data.

[0047] In step S111, the 6G UPF 30E sends a PFCP Session Report request (Downlink Data Report) to the 6G SMF 30D.

[0048] In step S112, the 6G SMF 30D sends a Namf_Communication_N1N2MessageTransfer request to the 6G AMF 30C.

[0049] In step S113, the 6G AMF 30C sends a Namf_Communication_N1N2MessageTransfer response to the 6G SMF 30D.

[0050] In steps S111-S113, the presence of downlink data is notified from the 6G SMF 30D to the 6G AMF 30C using the PFCP protocol and SBI interface within the 6GS core network, and appropriate communication processing is performed.

[0051] In step S114, the 6G AMF 30C may suppress paging using other IPR mechanisms. In this step, the 6G AMF can avoid unnecessary paging by using other IPR-based methods.

[0052] In step S115 of Figure 4C, UE 20 moves to 6GS. In this step, UE 20 physically or logically transitions its connection to the 6G system (6GS). The move to 6GS is performed to improve QoS and network efficiency.

[0053] In step S116, the UE 20 sends an RRCSetupRequest to the 6G NB 30B. In this step, the UE 20 requests the 6GS NB 30B to initialize the RRC connection. This is the procedure for initiating communication in 6GS.

[0054] In step S117, the 6G NB 30B sends RRCSetup to the UE 20. The 6G NB 30B sends an RRC setup message to the UE 20 to configure the RRC connection. This message contains the necessary resource configuration information.

[0055] In step S118, UE 20 sends RRCSetupComplete (dedicatedNAS-Message (Registration request)) to 6G NB 30B. If the UE is dual-registered, a Service request may be used instead of a Registration request. In this step, the UE notifies that the RRC setup is complete and sends RRCSetupComplete, which includes a dedicated NAS message. This NAS message represents a registration request in 6GS.

[0056] In step S119, the 6G NB 30B sends an Initial UE message (NAS-PDU (Registration request)) to the 6G AMF 30C.

[0057] In step S120, the 6G AMF 30C sends an Nsmf_PDUSession_UpdateSMContext request to the 6G SMF 30D.

[0058] In step S121, the 6G SMF 30D sends a PFCP Session Modification request to the 6G UPF 30E.

[0059] In step S122, the 6G UPF 30E sends a PFCP Session Modification response to the 6G SMF 30D.

[0060] In step S123, the 6G SMF 30D sends the Nsmf_PDUSession_UpdateSMContext response to the 6G AMF 30C.

[0061] In steps S119-S123, the initial UE message is forwarded to the AMF, and a PDU session update is performed.

[0062] In step S124, the 6G AMF 30C sends a PDU Session Resource Setup request to the 6G NB 30B.

[0063] In step S125, the 6G NB 30B sends RRCReconfiguration to the UE 20.

[0064] In step S126, UE 20 sends RRCReconfigurationComplete to 6G NB 30B.

[0065] In step S127, the 6G NB 30B sends a PDU Session Resource Setup response to the 6G AMF 30C.

[0066] In step S128, the 6G AMF 30C sends an Nsmf_PDUSession_UpdateSMContext request to the 6G SMF 30D.

[0067] In step S129, the 6G SMF 30D sends a PFCP Session Modification request to the 6G UPF 30E.

[0068] In step S130, the 6G UPF 30E sends a PFCP Session Modification response to the 6G SMF 30D.

[0069] In step S131, the 6G SMF 30D sends an Nsmf_PDUSession_UpdateSMContext response to the 6G AMF 30C.

[0070] In step S132, the 6G AMF 30C sends a Downlink NAS Transport (NAS-PDU (Registration accept)) to the 6G NB 30B.

[0071] In step S133, the 6G NB 30B sends a DLInformationTransfer (dedicatedNAS-Message (Registration accept)) to the UE 20.

[0072] In steps S124-S133, the PDU session resource is set up and the registration response is notified. This completes the configuration for UE 20 to fully resume communication within 6GS.

[0073] In step S134 of Figure 4D, the 6G UPF 30E transmits DL voice media to the UE 20. In this step, the 6G UPF transfers downlink voice data to the UE. This indicates that voice communication on 6GS is functioning correctly.

[0074] In step S135, UE 20 sends a SIP Register to P-CSCF 30F. UE 20 sends a SIP registration request for re-registration within the IMS network. This procedure notifies IMS of UE 20's new IP address.

[0075] In step S136, P-CSCF 30F sends SIP 200 OK to UE 20. P-CSCF 30F accepts the SIP registration and sends a 200 OK response to the UE, completing the registration process.

[0076] In step S137, if buffered DL SIP messages exist, the P-CSCF 30F sends DL SIP messages to the UE 20 with the destination IP address set to the target IP address. In this step, the P-CSCF 30F forwards buffered SIP messages using the new IP address. This prevents session interruption.

[0077] According to Embodiment 1, it is possible to prevent interruptions in IMS voice communication during movement between 5GS and 6GS. Furthermore, by ensuring the independence of 5GS and 6GS, the complexity of the system can be reduced and the efficiency of the network can be improved.

[0078] (Example 2) Example 2 demonstrates a method for continuing IMS voice communication when there are no PDU sessions held within 6GS. In Example 2, UE 20 uses SIP re-INVITE with dummy values ​​to enable a seamless transition to the IMS network. After the network transition, renegotiation including the new IP address is performed to ensure the continuation of voice media.

[0079] An example of the operation of the communication system of Embodiment 2 will be explained using Figures 5A-5C. Figure 5A-5C shows a series of operations, but this embodiment may be applied to some of the steps shown in the figure or to any combination of multiple steps.

[0080] In the example shown in Figure 5, an IMS voice call is in progress, and 5GS is providing service to UE 20. Unlike Example 1, Example 2 assumes that UE 20 does not maintain a PDU session within 6GS.

[0081] In step S201 of Figure 5A, UE 20 decides to move to 6GS.

[0082] In step S202, UE 20 sends a SIP re-INVITE.

[0083] In step S203, UE 20 sends SIP re-INVITE (Reason header=IP-CAN change, SDP offer (c=dummy)) to P-CSCF 30F. IP-CAN change is an optional function. Unlike step S103 in Figure 4A of Example 1, a dummy value is specified in the c field of the SDP offer in step S203. The dummy value is a temporary value before the actual IP address is set. In this way, UE 20 includes information in the SIP re-INVITE message that a dummy value has been set as the destination for the voice media.

[0084] In step S204, if a DL SIP message exists based on the IP-CAN change, the P-CSCF 30F buffers the DL SIP message.

[0085] In step S205, P-CSCF 30F sends Configure AGW Connection Point (towards UE)(Remote Connection Address=dummy) to IMS AGW 30G.

[0086] In step S206, the IMS AGW 30G sends a Configure AGW Connection Point Ack to the P-CSCF 30F.

[0087] In step S207, the IMS AGW 30G starts buffering the DL audio media.

[0088] In step S208, P-CSCF 30F sends a SIP re-INVITE to IMS AS 30H.

[0089] In step S209, IMS AS 30H sends SIP 200 OK to P-CSCF 30F.

[0090] In step S210, P-CSCF 30F sends SIP 200 OK to UE 20.

[0091] In step S211 of Figure 5B, UE 20 moves to 6GS. The UE initiates the process of migrating its connection to 6GS due to a change in network conditions or service requirements.

[0092] In step S212, the registration procedure in 6GS is performed. In step S213, the PDU session establishment procedure in 6GS is performed. In steps S212-S213, the registration and PDU session establishment procedures in 6GS are performed. This ensures that the UE has the resources to enable communication within 6GS. UE 20 recognizes that an IP address has been assigned to its terminal (UE 20) in 6GS.

[0093] In step S214, UE 20 sends SIP Register to P-CSCF 30F. In step S215, P-CSCF 30F sends SIP 200 OK to UE 20. In step S216, if buffered DL SIP messages exist, P-CSCF 30F sets the destination IP address to the target IP address and sends the DL SIP messages to UE 20. Steps S214-S216 perform SIP registration and the forwarding of buffered SIP messages.

[0094] In step S217 of Figure 5C, UE 20 sends a SIP re-INVITE (SDP offer (c=UE IP address of 6GS PDU session)) to P-CSCF 30F. The SIP re-INVITE includes information that the IP address assigned to the terminal in 6GS is set as the destination for the voice media. The SIP re-INVITE in step S217 is an example of a second voice call configuration change request message.

[0095] In step S218, P-CSCF 30F sends Configure AGW Connection Point (towards UE) (Remote Connection Address=UE IP address of 6GS PDU session) to IMS AGW 30G.

[0096] In step S219, the IMS AGW 30G sends a Configure AGW Connection Point Ack to the P-CSCF 30F.

[0097] In step S220, P-CSCF 30F sends a SIP re-INVITE to IMS AS 30H.

[0098] In step S221, IMS AS 30H sends SIP 200 OK to P-CSCF 30F.

[0099] In step S222, P-CSCF 30F sends SIP 200 OK to UE 20.

[0100] In step S223, the IMS AGW 30G sends the DL voice media to the UE 20.

[0101] In steps S217-S223, the SIP session is updated using the new IP address in 6GS and the voice media is transferred.

[0102] According to Embodiment 2, even in the case of IMS voice communication where there is no PDU session held within 6GS, interruption of IMS voice communication during movement between 5GS and 6GS can be prevented. Furthermore, by ensuring the independence of 5GS and 6GS, the complexity of the system can be reduced and the efficiency of the network can be improved.

[0103] (Device Configuration) Next, an example of the functional configuration of the base station 10, network node 30, and terminal 20 that perform the processing and operations described above will be explained. The base station 10, network node, and terminal 20 include the functions to perform the embodiments described above. However, the base station 10, network node, and terminal 20 may each have only some of the functions in the embodiments.

[0104] <Base Station and Network Nodes> Figure 6 shows an example of the functional configuration of a base station 10 and a network node. As shown in Figure 6, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Figure 6 is merely an example. The functional classifications and names of the functional units can be anything as long as they can perform the operation according to this embodiment. Note that the network node may have the same functional configuration as the base station 10. Furthermore, a network node having multiple different functions in the system architecture may be composed of multiple network nodes separated by function.

[0105] The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 or other network node and transmitting the signal by wire or wireless. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 or other network node and obtaining information from the received signal, for example, information of a higher layer. A communication unit including the transmitting unit 110 and the receiving unit 120 may be configured.

[0106] The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20 in a storage device, and reads them from the storage device as needed.

[0107] The control unit 140 performs the processes described in the embodiment. The control unit 140 also performs processing related to communication with the terminal 20. The signal transmission function in the control unit 140 may be included in the transmission unit 110, and the signal reception function in the control unit 140 may be included in the reception unit 120.

[0108] <Terminal> Figure 7 is a diagram showing an example of the functional configuration of terminal 20. As shown in Figure 7, terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Figure 7 is merely an example. Any functional classification and name of functional unit is acceptable as long as it can perform the operation according to this embodiment. In addition, the communication device that becomes the resource holder 20 may have a functional configuration similar to that of terminal 20.

[0109] The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and obtains signals from higher layers from the received physical layer signals. The receiving unit 220 also has the function of receiving control signals or reference signals transmitted from network nodes. A communication unit including the transmitting unit 210 and the receiving unit 220 may be configured.

[0110] The setting unit 230 stores various setting information received from network nodes by the receiving unit 220 in a storage device and reads it from the storage device as needed. The setting unit 230 also stores pre-configured setting information.

[0111] The control unit 240 performs the processing described in the embodiment. The signal transmission function in the control unit 240 may be included in the transmission unit 210, and the signal reception function in the control unit 240 may be included in the reception unit 220.

[0112] (Hardware Configuration) The block diagrams (Figures 6 and 7) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may be realized by combining the one device or the multiple devices with software.

[0113] Functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited.

[0114] For example, the base station 10, network node, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 8 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 according to one embodiment of the present disclosure. The network node may have a hardware configuration similar to that of the base station 10. The base station 10 and terminal 20 described above may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0115] In the following explanation, the term "device" can be replaced with "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices.

[0116] Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the storage device 1002 and auxiliary storage device 1003.

[0117] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001.

[0118] Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 6 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 7 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-described processes have been explained as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from the network via a telecommunications line.

[0119] The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of the present disclosure.

[0120] The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital multipurpose disk, a Blu-ray® disk), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

[0121] The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting and receiving antenna, amplifier section, transmitting and receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting and receiving section may be implemented in a physically or logically separated manner, with a transmitting section and a receiving section.

[0122] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0123] Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0124] Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components.

[0125] Figure 9 shows an example of the configuration of vehicle 2001. As shown in Figure 9, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect / embodiment described in this disclosure may be applied to a communication device mounted on vehicle 2001, for example, to the communication module 2013.

[0126] The drive unit 2002 consists of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0127] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2029 installed in the vehicle 2001 are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0128] Signals from various sensors 2021 to 2029 include current signals from current sensor 2021 for sensing motor current, front and rear wheel rotation speed signals acquired by rotation speed sensor 2022, front and rear wheel air pressure signals acquired by air pressure sensor 2023, vehicle speed signals acquired by vehicle speed sensor 2024, acceleration signals acquired by acceleration sensor 2025, accelerator pedal depression signals acquired by accelerator pedal sensor 2029, brake pedal depression signals acquired by brake pedal sensor 2026, shift lever operation signals acquired by shift lever sensor 2027, and detection signals acquired by object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0129] The Information Service Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Service Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The Information Service Unit 2012 may include input devices that accept input from the outside (e.g., keyboard, mouse, microphone, switch, button, sensor, touch panel, etc.) and output devices that perform output to the outside (e.g., display, speaker, LED lamp, touch panel, etc.).

[0130] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0131] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29 provided in the vehicle 2001.

[0132] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information with external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0133] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021-2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include the information based on the above input.

[0134] The communication module 2013 receives various information (traffic information, signal information, inter-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021-2029, etc., provided in the vehicle 2001.

[0135] <Note> (Note 1) A terminal comprising: a communication unit that performs voice communication in a first system (e.g., 5GS); and a control unit that decides to continue the voice communication in a second system (e.g., 6GS), wherein the communication unit transmits a first voice call configuration change request message (e.g., SIP re-INVITE) to a network node (e.g., P-CSCF) that is used in common by both the first and second systems, requesting the reconfiguration of the voice communication.

[0136] (Note 2) The terminal as described in Note 1, wherein the control unit includes information that a dummy value has been set as the destination of the voice media in the first voice call setting change request message.

[0137] (Note 3) The terminal according to Note 1, wherein the communication unit receives a response message to the first voice call setting change request message from the network node, the communication unit connects to the second system, the control unit recognizes that an IP address has been assigned to the terminal in the second system, and the communication unit sends a second voice call setting change request message (e.g., SIP re-INVITE) to the network node, which includes information setting the IP address as the destination for the voice media.

[0138] (Note 4) The terminal as described in Note 1, wherein the control unit includes in the first voice call setting change request message information setting an IP address assigned to the terminal in the second system as the destination of the voice media.

[0139] (Note 5) The terminal described in Note 1, wherein the first voice call setting change request message includes information indicating that the network system accommodating voice communication is being changed.

[0140] (Appendix 6) An IMS access gateway comprising: a receiving unit that receives a message from a first network node (e.g., P-CSCF) requesting the setting of a connection point with a dummy value specified as the destination, and a receiving unit that receives IP packets from a second network node (e.g., another IMS access gateway); a control unit that buffers the IP packets; and a transmitting unit that transmits the IP packets, wherein the receiving unit receives a message from the first network node requesting the setting of a connection point with an IP address specified as the destination, and the transmitting unit transmits the buffered IP packets with the IP address as the destination.

[0141] Any of the provisions in Appendix 1-6 can prevent interruptions to IMS voice communication during travel between 5GS and 6GS. Furthermore, ensuring the independence of 5GS and 6GS reduces system complexity and improves network efficiency.

[0142] (Supplement to Embodiments) Although these embodiments have been described above, the disclosed invention is not limited to these embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention, and matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. The processing procedures described in the embodiments may be rearranged as long as they do not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to this embodiment and the software operated by the processor of the terminal 20 according to this embodiment may be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium.

[0143] Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling), broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0144] Each aspect / embodiment described in this disclosure refers to LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (where x is, for example, an integer or decimal)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20 may apply to at least one system utilizing UWB (Ultra-WideBand), Bluetooth®, or other appropriate systems, and to next-generation systems extended, modified, created, or defined based thereon. Alternatively, multiple systems may be applied in combination (e.g., a combination of at least one of LTE and LTE-A with 5G).

[0145] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0146] In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0147] The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

[0148] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices.

[0149] The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value).

[0150] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0151] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0152] The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0153] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0154] The terms “system” and “network” as used in this disclosure are interchangeable.

[0155] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0156] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way.

[0157] In this disclosure, terms such as "Base Station (BS)", "wireless base station", "base station equipment", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0158] A base station can accommodate one or more (e.g., three) cells. If a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage.

[0159] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0160] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0161] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or several other appropriate terms.

[0162] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0163] Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything)). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel.

[0164] Similarly, the term "user terminal" in this disclosure may be replaced with "base station." In this case, the base station may be configured to have the same functions as the user terminal described above.

[0165] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0166] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0167] The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard.

[0168] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0169] Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way.

[0170] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0171] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0172] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0173] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0174] Each aspect / embodiment described in this disclosure may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0175] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0176] 10 Base station 110 Transmitting unit 120 Receiving unit 130 Setting unit 140 Control unit 20 Terminal 210 Transmitting unit 220 Receiving unit 230 Setting unit 240 Control unit 30 Network node 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheel 2008 Rear wheel 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driver assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port (I / O port)

Claims

1. A terminal comprising: a communication unit that performs voice communication in a first system; and a control unit that decides to continue the voice communication in a second system, wherein the communication unit transmits a first voice call setting change request message to a network node used in common by both the first system and the second system, requesting the reconfiguration of the voice communication.

2. The terminal according to claim 1, wherein the control unit includes information in the first voice call setting change request message that a dummy value has been set as the destination of the voice media.

3. The terminal according to claim 1, wherein the communication unit receives a response message from the network node to the first voice call setting change request message, the communication unit connects to the second system, the control unit recognizes that an IP address has been assigned to the terminal in the second system, and the communication unit transmits a second voice call setting change request message to the network node, which includes information that the IP address has been set as the destination for the voice media.

4. The terminal according to claim 1, wherein the control unit includes in the first voice call setting change request message information setting an IP address assigned to the terminal in the second system as the destination of the voice media.

5. The terminal according to claim 1, wherein the first voice call setting change request message includes information indicating that a network system accommodating voice communications is being changed.

6. An IMS (IP Multimedia Subsystem) access gateway comprising: a receiving unit that receives a message from a first network node requesting the setting of a connection point with a dummy value specified as the destination, and receives IP packets from a second network node; a control unit that buffers the IP packets; and a transmitting unit that transmits the IP packets, wherein the receiving unit receives a message from the first network node requesting the setting of a connection point with an IP address specified as the destination, and the transmitting unit transmits the buffered IP packets with the IP address as the destination.

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