Base station device, control method and program

Abstract

When a terminal device's connection destination is switched from a first wireless communication system (NR system) to a second wireless communication system (LTE system) to provide a voice communication service, the occurrence of processing contention is prevented. In an eNB 31 (base station device), when a handover (HO) request for a UE 10 connected to an NR system 20 to hand over from the NR system 20 to an LTE system 30 for voice communication is received from an MME 35 of the LTE system 30, an HO processing unit 321 performs an HO process according to the HO request. Upon completion of the HO process, a TAU processing unit 322 performs an update process (TAU process) for updating a location registration area of ​​the UE 10 managed by the MME 35. A communication control unit 323 controls communication with the UE 10 so as to suppress handover of the UE 10 in the LTE system 30 while the TAU process is being performed.

Description

[Technical field]

[0001] The present invention relates to a base station device, a control method, and a program in a wireless communication system (mobile communication system). [Background technology]

[0002] The EPS (Evolved Packet System) fallback method is defined as one of the methods for providing voice communication services in a wireless communication system (mobile communication system) of the 5th generation (5G) standard (also called the NR (New Radio) standard) of the 3rd Generation Partnership Project (3GPP (registered trademark)). In the EPS fallback method, a terminal that is waiting or communicating in an NR standard wireless communication system (NR system or 5G NR system) is handed over to an LTE (Long Term Evolution) / LTE Advanced standard wireless communication system (LTE system), and a voice communication service is provided in the LTE system. The NR system is also called a 5G system (5GS), and the LTE system is also called EPS.

[0003] In the EPS fallback method, after the handover (HO) process from the NR system to the LTE system is completed, the management of the location registration area of ​​the terminal needs to be transferred from the NR system to the LTE system. For this reason, after the HO process is completed, a tracking area update (TAU) process is performed to update the location registration area (tracking area) of the terminal (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Shimizu, Abe, Miyazaki, and Obara, "Overview of Core Network Technology for Realizing Voice Calls in 5G SA Method," NTT DOCOMO Journal, Vol. 30, No. 4, January 2023. Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned method, the next HO process (e.g., HO process between cells due to a deterioration in reception quality) of the terminal in the LTE system can be performed immediately after the HO process from the NR system to the LTE system is completed. However, if the next HO process of the terminal is started in the LTE system while the TAU process is being performed, a conflict occurs between the HO process and the TAU process. As a result, the TAU process cannot be completed, and the establishment of the voice call fails.

[0006] Therefore, the present invention provides a technique for preventing the occurrence of processing contention when a voice communication service is provided by switching a connection destination of a terminal device from a first wireless communication system (NR system) to a second wireless communication system (LTE system). [Means for solving the problem]

[0007] A base station device according to one embodiment of the present invention is a base station device of a second wireless communication system that is a handover destination from a base station device of a first wireless communication system, and comprises: a first processing means that, when a handover request for a terminal device connected to the first wireless communication system to hand over from the first wireless communication system to the second wireless communication system to perform voice communication is received from a mobile management device of the second wireless communication system, performs handover processing in accordance with the handover request; a second processing means that, when the handover processing is completed, performs an update processing for updating the location registration area of ​​the terminal device managed by the mobile management device; and a second processing means that prevents measurement settings for handover of the terminal device in the second wireless communication system from being transmitted to the terminal device while the update processing is being performed. When transmitting a response to the handover request received from the mobility management device to the mobility management device, the response is transmitted to the mobility management device without including the measurement configuration. and a communication control means for controlling the communication. Effect of the Invention

[0008] According to the present invention, it is possible to prevent the occurrence of processing contention when switching the connection destination of a terminal device from a first wireless communication system (NR system) to a second wireless communication system (LTE system) to provide a voice communication service. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a communication system. [Diagram 2] FIG. 2 is a block diagram showing an example of the hardware configuration of a base station device (eNB). [Diagram 3] FIG. 2 is a block diagram showing an example of a functional configuration of a base station device (eNB). [Figure 4] FIG. 4 is a sequence diagram showing an example of a sequence of processes executed in the communication system. [Diagram 5] FIG. 4 is a sequence diagram showing an example of a sequence of processes executed in the communication system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] <Communication system configuration> FIG. 1 illustrates a configuration example of a communication system according to an embodiment of the present disclosure. In this embodiment, a communication system that provides a voice communication service by switching a connection destination of a terminal device from a first wireless communication system to a second wireless communication system will be described. The first wireless communication system and the second wireless communication system are cellular communication systems that support different wireless communication technologies (RATs). In this embodiment, as an example, the first wireless communication system is configured as a cellular communication system (NR system) that complies with the 3GPP NR standard (5G standard). Also, the second wireless communication system is configured as a cellular communication system (LTE system) that complies with the 3GPP LTE / LTE Advanced standard.

[0012] The NR system 20 includes a base station device (gNB) 21 and a core network 200. The core network 200 includes an access and mobility management function (AMF) 25 as a mobility management device that performs mobility management of terminal devices. The core network 200 is also referred to as 5GC (5G Core). The core network 200 is connected to a data network 40 such as the Internet.

[0013] The LTE system 30 includes a base station device (eNB) 31 and a core network 300. The core network 300 includes an MME (Mobility Management Entity) 35 as a mobility management device that performs mobility management of terminal devices. The core network 300 is also called an EPC (Evolved Packet Core). The core network 300 is connected to a data network 40.

[0014] The user equipment (UE) 10 is a terminal device (wireless terminal) compatible with the RAT of the NR standard and the RAT of the LTE / LTE Advanced standard, and is, for example, configured as a smartphone or a tablet terminal. The UE 10 can access the data network 40 via the gNB 21 and the core network 200 by wirelessly accessing the gNB 21 of the NR system 20. The UE 10 can also access the data network 40 via the eNB 31 and the core network 300 by wirelessly accessing the eENB 31 of the LTE system 30.

[0015] In the communication system of the present embodiment, the provision of a voice communication service to a terminal device (UE 10) is performed by the LTE system 30. For this reason, when starting to provide a voice communication service to a terminal device that is waiting or communicating in the NR system 20, it is necessary to switch (handover) the connection destination of the terminal device from the NR system 20 to the LTE system 30. Such switching from the NR system 20 to the LTE system 30 is also referred to as EPS fallback, as described above.

[0016] In this embodiment, an example will be described in which a voice communication service is provided to UE 10 in a communication system in a state in which UE 10 is located in an area where a cell of gNB 21 and a cell of eNB 31 overlap.

[0017] <Configuration of base station device (eNB)> 2 shows an example of a hardware configuration of a base station device (eNB 31) of a second wireless communication system (LTE system 30) according to the present embodiment. The eNB 31 includes one or more processors 311, a ROM 312, a RAM 313, a storage device (storage) 314 such as an HDD, and a communication device 315.

[0018] In the eNB31, a program for implementing each function of the eNB31, which is described later and is stored in, for example, the ROM312, the RAM313, or the storage 314, is executed by a processor 311 such as a CPU. The processor 311 may be replaced by one or more processors such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor). The communication device 315 is a communication interface for communicating with an external device (such as a terminal device or a network node of the core network 300) under the control of the processor 311. The communication device 315 includes a wireless communication interface for wireless communication with a terminal device (wireless terminal) in a cell formed by the eNB31. The eNB31 may have a plurality of communication devices 315 each connected to a different destination.

[0019] 3 shows an example of a functional configuration (software configuration) of a base station device (eNB31) of a second wireless communication system (LTE system 30) according to this embodiment. The eNB31 has a handover (HO) processing unit 321, a location registration area update (TAU) processing unit 322, and a communication control unit 323. These functional units of the eNB31 are realized in the eNB31 by the processor 311 executing a program stored in, for example, the ROM 312, the RAM 313, or the storage 314.

[0020] The HO processing unit 321 is configured to perform handover (HO) processing of a terminal device (UE 10) in a cell of the eNB 31. In this embodiment, when the HO processing unit 321 receives a handover (HO) request from the MME 35 for the terminal device (UE 10) connected to the NR system 20 to hand over from the NR system 20 to the LTE system 30 and perform voice communication, the HO processing unit 321 performs HO processing according to the HO request.

[0021] The TAU processing unit 322 is configured to perform an update process (TAU process) for updating a location registration area (tracking area) of the terminal device (UE 10) in a cell of the eNB 31, which is managed by the MME 35. In this embodiment, the TAU processing unit 322 performs the TAU process of the terminal device (UE 10), which is managed by the MME 35, when the HO process from the NR system 20 to the LTE system 30 for the terminal device (UE 10) to perform voice communication is completed.

[0022] The communication control unit 323 is configured to control communication by the communication device 315. For example, the communication control unit 323 controls communication performed in the HO processing by the HO processing unit 321 and the TAU processing by the TAU processing unit 322. In this embodiment, as described later, the communication control unit 323 controls communication with the terminal device (UE 10) so as to suppress handover of the terminal device (UE 10) in the LTE system 30 while the TAU processing is being performed.

[0023] <Processing Procedure> FIG. 4 is a sequence diagram showing an example of a processing sequence executed in a communication system, and shows a sequence of a comparative example with respect to a sequence (FIG. 5) in this embodiment described later.

[0024] This example shows an example of an EPS fallback procedure in which the connection destination of the UE 10 is switched from the NR system 20 to the LTE system 30 (i.e., a handover is performed) and a voice communication service is provided in the LTE system 30. In this example, it is assumed that the UE 10 is in a standby or communicating state in the NR system 20 and is present in a cell (NR cell) formed by the gNB 21. In this example, the gNB 21 is a serving base station that provides communication services to the UE 10 in the cell.

[0025] When a call is made by the UE 10 or an incoming call is made to the UE 10, a process for establishing a voice call to the UE 10 is started in the NR system 20. At S401, the UE 10 transmits a Measurement Report message to a serving gNB (gNB21). The measurement report message includes information indicating measurement results such as received power (RSRP: Reference Signal Received Power) or received quality (RSRQ: Reference Signal Received Quality) for the serving cell (cell of the gNB21) and adjacent LTE cells. The gNB21 determines an LTE cell to be a handover destination for EPS fallback based on the information included in the measurement report message. In this example, it is assumed that the cell of the eNB31 is determined as the handover destination.

[0026] In S402, the gNB 21 transmits a Handover Required message requesting execution of HO processing of the UE 10 from the NR system 20 (NR cell) to the LTE system 30 (LTE) to the AMF 25. The Handover Required message may include a cell ID of the handover destination cell (in this example, the cell of the eNB 31) and the like.

[0027] The AMF 25 which has received the Handover Required message selects a target MME in the LTE system 30 in S403, and transmits a Forward Relocation Request message to the MME notifying the MME that the UE 10 will be handed over. In this example, it is assumed that the Forward Relocation Request message is transmitted to the MME 35. The MME 35 which has received the Forward Relocation Request message transmits a Handover Request message to the eNB 31 corresponding to the LTE cell of the handover destination in S404.

[0028] The eNB 31, which has received the Handover Request message from the MME 35, starts HO processing for the UE 10 according to the received message (HO request). First, in S405, the eNB 31 transmits a Handover Request Acknowledge message to the MME 35 as a response to the Handover Request message. The Handover Request Acknowledge message includes Measurement Configuration. The measurement configuration is included in the Handover Request Acknowledge message for handover (handover between cells, etc.) in the LTE system 30 of the handover destination, and is set for the UE 10. The Handover Request Acknowledge message further includes a "Target to Source Transparent Container" IE (information element) for transmitting wireless-related information from the handover destination to the handover source, and the like.

[0029] When the MME 35 receives the Handover Request Acknowledge message from the eNB 31, in S406, the MME 35 transmits a Forward Relocation Response message to the AMF 25 as a response to the Forward Relocation Request message (S403).

[0030] Upon receiving the Forward Relocation Response message from the MME 35, the AMF 25 transmits a Handover Command message to the gNB 21, which is the handover source gNB, in S407. The Handover Command message includes information in the Handover Request Acknowledge message received by the MME 35 from the eNB 31.

[0031] When the gNB 21 receives the Handover Command message from the AMF 25, it transmits a mobilityFromNRCommand message to the UE 10 in S408. The mobilityFromNRCommand message is an RRC message transmitted to the UE 10 as a handover command instructing a handover from the NR system 20 (NR cell) to the LTE system 30 (LTE cell). The mobilityFromNRCommand message includes the measurement configuration set in the Handover Request Acknowledge message (S405). Therefore, the UE 10 operates to perform measurements for handover in the LTE system 30 (measurements such as RSRP or RSRQ) according to the measurement configuration included in the received message, and transmit a measurement report to the eNB 31.

[0032] The UE 10 connects to the cell of the eNB 31 according to the mobilityFromNRCommand message. If the connection is successful, in S409, the eNB 31 transmits an RRC Reconfiguration Complete message indicating completion of handover. In S410, the eNB 31 receives the message and transmits a Handover Notify message indicating completion of handover of the UE 10 to the MME 35. Through the above process, the eNB 31 completes the HO process of the UE 10 in response to the HO request received from the MME 35. When the HO process from the NR system 20 (NR cell) to the LTE system 30 (LTE cell) is completed, the UE 10 becomes able to perform the next HO process in the LTE system 30 based on the measurement according to the above-mentioned measurement configuration immediately after the completion of the HO process.

[0033] After the above-mentioned HO process is completed, the eNB31 performs a tracking area update (TAU) process for updating the location registration area (tracking area) of the UE10, which is managed by the MME35, in response to receiving a TAU request (TAU accept) message from the UE10. Specifically, the eNB31 transmits a TAU request message requesting an update of the tracking area of ​​the UE10 to the MME35. The TAU request message is included in a UL Information Transfer message in S411 and transmitted from the UE10 to the eNB31. The TAU request message is further included in an UPlink NAS Transport message in S412 and transmitted from the eNB31 to the MME35. The MME35 updates the tracking area of ​​the UE10 according to the TAU request message received from the UE10 in this way.

[0034] In the example of FIG. 4, while the TAU process is being performed, the next HO process (S421 to S427) of the UE 10 is started in the LTE system 30 as described above. Specifically, in S421, the UE 10 performs measurement according to the measurement configuration received in S408 as described above, and transmits a Measurement Report message to the eNB 31. The eNB 31 determines a handover destination base station of the UE 10 in the LTE system 30 based on the received measurement report message. In this example, the eNB 32 is determined as the handover destination base station. That is, the HO process of the UE 10 is performed with the eNB 31 as the source eNB (SeNB) and the eNB 32 as the target eNB (TeNB).

[0035] In S422, eNB31 (SeNB) transmits to eNB32 (TeNB) a Handover Request message requesting execution of handover of UE 10. When eNB32 (TeNB) receives the Handover Request message and decides to accept handover of UE 10, in S423, eNB32 (TeNB) transmits a Handover Request Acknowledge message to eNB31 (SeNB) as a response to the Handover Request message.

[0036] Upon receiving the Handover Request Acknowledge message, the eNB31 (SeNB) transmits an RRC Connection Reconfiguration message including information such as the base station (cell) of the handover destination to the UE 10 in S424. The eNB31 (SeNB) further transmits an SN Status Transfer message including session information of the UE 10 to the eNB32 (TeNB) in S425. The UE 10 also connects to the cell of the eNB32 (TeNB), and upon successful connection, transmits an RRC Reconfiguration Complete message indicating completion of the handover to the eNB32 (TeNB) in S426.

[0037] In this example, after UE 10 completes connection to the cell of eNB 32 (TeNB), in S413, MME 35, which has updated the tracking area of ​​UE 10 in accordance with the TAU request message as described above, transmits a TAU accept message to eNB 31. The TAU accept message is included in a Downlink NAS Transport message and transmitted from MME 35 to eNB 31.

[0038] In this example, eNB31 attempts to transfer the received TAU accept message to UE10 in a Downlink Information Transfer message in S414. However, at this timing, since the switching of the connection of UE10 from the cell of eNB31 (SeNB) to the cell of eNB32 (TeNB) is completed as described above, the Downlink Information Transfer message cannot be delivered to UE10. In this way, if the next HO process of UE10 is performed while the TAU process of UE10 is being performed after the HO process to the LTE system 30 is completed, the HO process and the TAU process conflict with each other, and the TAU process cannot be completed. As a result, the establishment of a voice call to UE10 fails.

[0039] Also, in this example, in S427, the eNB 32 (TeNB) transmits a Path Switch Request message to the MME 35, requesting switching of a path used for transmitting data to and from the UE 10. However, in this example, since the tracking area of ​​the UE 10 has been updated by the TAU process in the MME 35, switching of the path for the UE 10 cannot be performed, and the HO process cannot be completed. In this way, the HO process may not be completed due to the contention between the HO process and the TAU process.

[0040] In this embodiment, when a connection destination of a terminal device (UE 10) is switched from a first wireless communication system (NR system 20) to a second wireless communication system (LTE system 30) to provide a voice communication service, the occurrence of processing contention is prevented. For this purpose, the base station device (eNB 31) of the LTE system 30 in this embodiment performs communication control to control communication with the UE 10 so as to suppress handover of the UE 10 in the LTE system 30 while the TAU processing of the UE 10 (update processing to update the location registration area of ​​the UE 10) is being performed after the HO processing of the UE 10 from the NR system 20 to the LTE system 30 is completed.

[0041] An example of the above-mentioned communication control by the base station device (eNB 31) of the LTE system 30 will be described below with reference to Fig. 5. In this example, the eNB 31 is configured to control communication for HO processing so that handover of the UE 10 in the LTE system 30 is not executable even if the HO processing of the UE 10 from the NR system 20 to the LTE system 30 is completed.

[0042] Fig. 5 is a sequence diagram showing an example of a sequence of processes executed in the communication system of this embodiment. In Fig. 5, the same reference numerals are used for steps that perform basically the same processes as those in the comparative example shown in Fig. 4, and the following mainly describes the parts that are different from the comparative example.

[0043] 5, as in FIG. 4, shows an example of an EPS fallback procedure in which the connection destination of the UE 10 is switched from the NR system 20 to the LTE system 30 (i.e., a handover is performed) to provide a voice communication service in the LTE system 30. In this example, it is assumed that the UE 10 is in a standby or communicating state in the NR system 20 and is present in a cell (NR cell) formed by the gNB 21. In this example, the gNB 21 is a serving base station that provides a communication service to the UE 10 in the cell.

[0044] When a call is made by the UE 10 or a call is received by the UE 10, the NR system 20 starts a process for establishing a voice call to the UE 10. The processes of S401 to S403 are performed in the same manner as in the comparative example (FIG. 4). The MME 35, which has received a Forward Relocation Request message from the AMF 25 in S403, transmits a Handover Request (HO request) message to the eNB 31 corresponding to the LTE cell of the handover destination in S404. This HO request is an example of a handover request for a terminal device (UE 10) connected to the first wireless communication system (NR system 20) to hand over from the first wireless communication system to the second wireless communication system (LTE system 30) and perform voice communication. In this manner, the eNB 31 receives the HO request from the mobility management device (MME 35) of the second wireless communication system (LTE system 30).

[0045] The eNB 31, which has received the Handover Request message from the MME 35, starts the HO process for the UE 10 according to the received message (handover request). At S405, the eNB 31 transmits a Handover Request Acknowledge message to the MME 35 as a response to the Handover Request message. In this embodiment, the eNB 31 operates so as not to include Measurement Configuration in this Handover Request Acknowledge message. In this way, when the eNB 31 transmits a response to the HO request received from the MME 35 to the MME 35, the eNB 31 transmits the response to the MME 35 without including the measurement configuration for handover (handover between cells, etc.) in the LTE system 30 that is the handover destination.

[0046] When the MME 35 receives the Handover Request Acknowledge message from the eNB 31, in S406, the MME 35 transmits a Forward Relocation Response message to the AMF 25 as a response to the Forward Relocation Request message (S403). When the AMF 25 receives the Forward Relocation Response message from the MME 35, in S407, the AMF 25 transmits a Handover Command message to the gNB 21.

[0047] When the gNB 21 receives the Handover Command message from the AMF 25, in S408, it transmits a mobilityFromNRCommand message to the UE 10. As described above, in this embodiment, since the Handover Request Acknowledge message (S405) does not include the measurement configuration, the mobilityFromNRCommand message transmitted from the gNB 21 to the UE 10 does not include the measurement configuration either. In a state where the measurement configuration is not received, the UE 10 does not perform measurements for handover in the LTE system 30 (measurements of RSRP or RSRQ, etc.), and does not transmit a measurement report to the eNB 31.

[0048] The processes of S409 to S410 are performed in the same manner as in the comparative example (FIG. 4). Upon completion of the process of S410, the eNB 31 completes the HO process for the UE 10 in response to the HO request received from the MME 35. In this example, as described above, since the UE 10 is in a state in which it has not received any configuration, even if the HO process is completed, the handover of the UE 10 in the LTE system 30 is not executable. Therefore, the next HO process for the UE 10 will not be started while the following TAU process (S411 to S416) is being performed after the HO process is completed.

[0049] In the TAU process, the processes of S411 to S412 are performed in the same manner as in the comparative example (FIG. 4) described above. After updating the tracking area of ​​the UE 10 according to the TAU request message received from the UE 10, the MME 35 transmits a TAU accept message to the UE 10. The TAU accept message is included in a Downlink NAS Transport message in S413 and transmitted from the MME 35 to the eNB 31. The TAU accept message is further included in a Downlink Information Transfer message in S414 and transmitted from the eNB 31 to the UE 10.

[0050] Upon receiving the TAU accept message, the UE 10 transmits a TAU completion message to the MME 35. In S415, the TAU completion message is included in a UL Information Transfer message and transmitted from the UE 10 to the eNB 31. In S416, the TAU completion message is further included in an UPlink NAS Transport message and transmitted from the eNB 31 to the MME 35. With the above, the TAU process of the UE 10 is completed.

[0051] After the TAU process is completed, when the eNB 31 (communication control unit 323) receives a bearer establishment request for establishing a bearer used for voice communication from the MME 35, the eNB 31 transmits a message including the above-mentioned Measurement Configuration to the UE 10. This enables the UE 10 to perform measurements for handover in the LTE system 30, and enables the next HO process for the UE 10.

[0052] Specifically, in S417, an E-RAB Setup Request message including an Active dedicated EPS bearer context request corresponding to a bearer establishment request for establishing a bearer used for voice communication is received from the MME 35. In response to receiving the message, the eNB 31 transmits a Measurement Configuration message to the UE 10. This message is transmitted as an RRC Configuration Reconfiguration message. The UE 10 that has received the message is then able to perform the next HO process.

[0053] As described above, in the eNB 31 (base station device) of this embodiment, when a handover request (HO request) for a UE 10 (terminal device) connected to an NR system 20 (first wireless communication system) to perform voice communication by handing over from the NR system 20 to an LTE system 30 (second wireless communication system) is received from an MME 35 (mobility management device) of the LTE system 30, the HO processing unit 321 performs handover processing (HO processing) according to the HO request. Upon completion of the HO processing, the TAU processing unit 322 performs an update processing (TAU processing) for updating the location registration area of ​​the UE 10 managed by the MME 35. The communication control unit 323 controls communication with the UE 10 so as to suppress handover of the UE 10 in the LTE system 30 while the TAU processing is being performed.

[0054] According to the present embodiment, the next HO process of the UE 10 is not started in the LTE system 30 while the TAU process is being performed, so that it is possible to prevent contention between the HO process and the TAU process. That is, it is possible to prevent the occurrence of processing contention when switching the connection destination of the terminal device (UE 10) from the first wireless communication system (NR system 20) to the second wireless communication system (LTE system 30) to provide a voice communication service. This makes it possible to prevent failure in establishing a voice call to the terminal device (UE 10).

[0055] [Other embodiments] The terminal device according to the above-described embodiment can be realized by a computer program for causing a computer to function as a server device. The computer program can be stored in a computer-readable storage medium and distributed, or can be distributed via a network.

[0056] Furthermore, with this invention, for example, when providing a voice communication service to a terminal device, it becomes possible to prevent failure to establish a voice call due to processing contention, which will contribute to achieving Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Develop resilient infrastructure, promote sustainable industrialization and foster innovation."

[0057] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0058] 10: UE, 21: gNB, 31: eNB, 25: AMF, 35: MME, 321: HO processing unit, 322: TAU processing unit, 323: communication control unit

Claims

1. A base station device of a second wireless communication system that is a handover destination from a base station device of a first wireless communication system, a first processing means for performing a handover process in accordance with a handover request received from a mobility management device of the second wireless communication system, the handover request being for a terminal device connected to the first wireless communication system to perform voice communication from the first wireless communication system to the second wireless communication system; a second processing means for performing an update process for updating a location registration area of ​​the terminal device, the location registration area being managed by the mobility management device, when the handover process is completed; a communication control means for transmitting a response to the handover request received from the mobility management device to the mobility management device without including the measurement configuration so that a measurement configuration for handover of the terminal device in the second wireless communication system is not transmitted to the terminal device while the update process is being performed; A base station device comprising:

2. The base station apparatus according to claim 1 , wherein the communication control means transmits, after the update process is completed, a message to the terminal apparatus for enabling a handover of the terminal apparatus in the second wireless communication system to be executed.

3. The base station apparatus according to claim 2 , wherein the communication control means transmits a message including the measurement configuration to the terminal apparatus after the update process is completed.

4. The base station device according to claim 3, wherein when the communication control means receives a bearer establishment request from the mobility management device to establish a bearer used for the voice communication after the update process is completed, the communication control means transmits a message including the measurement configuration to the terminal device.

5. The base station apparatus according to claim 3 , wherein the communication control means transmits, to the terminal apparatus, a radio resource control (RRC) connection reconfiguration message including the measurement configuration as the message including the measurement configuration.

6. The base station device according to claim 1 or 2, wherein the first wireless communication system is an NR system, and the second wireless communication system is an LTE system.

7. A method for controlling a base station device of a second wireless communication system that is a handover destination from a base station device of a first wireless communication system, comprising: receiving a handover request from a mobility management device of the second wireless communication system, the handover request being for a terminal device currently connected to the first wireless communication system to perform voice communication from the first wireless communication system to the second wireless communication system, performing a handover process in accordance with the handover request; performing an update process for updating a location registration area of ​​the terminal device managed by the mobility management device when the handover process is completed; a step of transmitting a response to the handover request received from the mobility management device to the mobility management device without including the measurement configuration so that a measurement configuration for handover of the terminal device in the second wireless communication system is not transmitted to the terminal device while the update process is being performed; A control method comprising:

8. A program for causing a processor of a base station device to execute the control method according to claim 7.

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