First communication device, method for the first communication device, program

Abstract

Since it is necessary to control the switching of communication devices with reduced load on a network, this first communication device comprises: an acquisition unit that acquires an index related to a distance between the first communication device and a terminal device; and a communication switching determination unit that when a voice service is requested from the terminal device, determines whether to switch a communication device that provides the voice service to the terminal device, from the first communication device to a second communication device having a wireless communication system different from the first communication device, on the basis of the index.

Description

Technical Field

[0001] The present invention generally relates to a mobile communication network.

Background Art

[0002] In recent years, communication terminals (e.g., User Equipment (UE)) that support multiple radio access technologies (RAT), such as Wideband Code Division Multiple Access (sometimes also referred to as W-CDMA or 3G), Long Term Evolution (sometimes also referred to as LTE or 4G), and New Radio (sometimes also referred to as NR or 5G), have become widespread. When such a communication terminal requests a voice service from a network node, the network to which the communication terminal is connected may not provide the voice service. In that case, the network node (e.g., a base station) to which the communication terminal is connected may switch the network to which the communication terminal is connected to a network using a different RAT and provide the voice service to the communication terminal (fallback).

[0003] This fallback is processed on the network side, but there is a possibility that network switching processing and the like on the network side may fail. Therefore, Patent Document 1 describes an invention in which the position identifiers of 4G and 3G cells in past fallbacks, the number of fallback failures, etc. are associated and recorded, and fallback is not performed for cells that are likely to fail in fallback.

[0004] Furthermore, with the explosive increase in communication terminals, it has become common practice to use beamforming technology, which utilizes the large array antennas installed in base stations. By effectively using beamforming technology, high-speed, high-capacity wireless communication in NR becomes possible. For example, in order for base stations divided into CU, DU, and RU to perform communication using beamforming, the beamforming technology described in Non-Patent Document 1, for example, can be used. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2019 / 071748 [Non-patent literature]

[0006] [Non-Patent Document 1] Kazuaki Takeda, et al., "Status of Study on Physical Layer Elemental Technologies and High-Frequency Band Utilization in 5G," NTT DOCOMO Technical Journal, Vol. 25, No. 3, October 2017. <https: / / www.nttdocomo.co.jp / binary / pdf / corporate / technology / rd / technical_journal / bn / vol25_3 / vol25_3_005jp.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the technology described in Patent Document 1 performs fallback control based on actual failures in attempting fallback, which may increase the network load while accumulating experience. This is common to switching of communication devices, including not only fallback but also handover. [Means for solving the problem]

[0008] A communication device according to a first aspect of this disclosure is a first communication device comprising: acquisition means for acquiring an index relating to the distance between the first communication device and a terminal device; and communication switching determination means for determining, based on the index, whether to switch the communication device that provides voice service to the terminal device from the first communication device to a second communication device having a different wireless communication method than the first communication device when a voice service is requested from the terminal device. It has.

[0009] A method according to a first aspect of the present disclosure is a method performed by a first communication device, which obtains an index related to the distance between the first communication device and a terminal device, and, when a voice service is requested from the terminal device, determines whether to switch the communication device that provides the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, based on the index. A program recorded on a computer-readable recording medium according to a first aspect of the present disclosure causes the first communication device to perform a process that obtains an index related to the distance between the first communication device and a terminal device, and, when a voice service is requested from the terminal device, determines whether to switch the communication device that provides the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, based on the index. [Effects of the Invention]

[0010] This disclosure provides a base station, a method, and a recording medium that enable switching control of communication devices that can reduce network load. It should be noted that this effect is only one of several effects that the multiple embodiments disclosed herein aim to achieve. Other effects will be revealed in the description herein or in the accompanying drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This is an explanatory diagram illustrating an example of network 1 in the first embodiment. [Figure 2] This is an explanatory diagram illustrating an example of a communication device 2 in the first embodiment. [Figure 3] This is an explanatory diagram illustrating an example of a communication device 3 in the first embodiment. [Figure 4] This is a flowchart illustrating an example of the operation of the communication device 2 in the first embodiment. [Figure 5] This is an explanatory diagram illustrating an example of multiple cells provided by the communication device 7 in the second embodiment. [Figure 6] This is an explanatory diagram illustrating an example of a communication device 7 in the second embodiment. [Figure 7] This is a flowchart illustrating an example of the operation of the communication device 7 in the second embodiment. [Figure 8] This is an explanatory diagram illustrating an example of a communication device 11 in the third embodiment. [Figure 9] This is a sequence diagram illustrating an example of the operation of the communication device 11 in the third embodiment. [Figure 10] This is an explanatory diagram illustrating an example of a communication device 14 in the fourth embodiment. [Figure 11] This is a flowchart illustrating an example of the operation of the communication device 14 in the fourth embodiment. [Figure 12] This is an explanatory diagram illustrating the configuration examples of the communication device 2, etc., in each embodiment. [Modes for carrying out the invention]

[0012] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary to simplify the explanation.

[0013] The embodiments described below can be implemented independently or in combination as appropriate. These multiple embodiments have novel features that differ from each other. Therefore, these multiple embodiments contribute to solving different objectives or problems and contribute to producing different effects.

[0014] As used herein, depending on the context, "(if)~then" may be construed to mean "when", "at or around the time", "after", "upon", "in response to determining", "in accordance with a determination", or "in response to detecting". These expressions may be construed to have the same meaning depending on the context.

[0015] <The first embodiment> Fig. 1 shows a configuration example of network 1 in this embodiment, and Fig. 2 shows a configuration example of communication device 2 in this embodiment. For example, communication devices 2 and 3 in Fig. 1 may be base stations that support radio communication technologies or radio communication methods defined in the Third Generation Partnership Project (3GPP (registered trademark)), such as Wideband Code Division Multiple Access (W-CDMA), Long Term Evolution (LTE), or New Radio (NR). Communication devices 2 and 3 each provide (operate) at least one radio communication area (cell). In Fig. 1, communication device 2 provides cell 20, and communication device 3 provides cell 30. Communication devices 2 and 3 may each provide one cell, or each provide a plurality of cells. When there are a plurality of cells, some or all of the cells may overlap. The radio access technology (RAT) to which the communication services provided by communication devices 2 and 3 to terminal device 4 conform may be different in each communication device. Also, at least one of communication devices 2 and 3 provides a radio communication service (including a data communication service and a voice service) to terminal device 4. The voice service may be, for example, Voice over LTE (VoLTE) or Voice over NR (VoNR).

[0016] Communication devices 2 and 3 are connected to each other by interface 5. Interface 5 may be, for example, an X2 interface or an Xn interface. Also, communication devices 2 and 3 are connected to upper device 100 by interface 6. Interface 6 may be, for example, an S1 interface or an NG interface, and the upper device may be a core network node. Also, the core network node may be a Mobile Management Entity (MME) or an Access and Mobility Management Function (AMF).

[0017] The number of target terminal devices in this embodiment is not particularly limited; there may be only one or multiple devices. Also, as mentioned above, the wireless communication technology or wireless communication method supported by communication device 2 and communication device 3 is not particularly limited. In the following explanation, for the sake of simplicity, we will describe an example where there is one target terminal device, communication device 2 is a base station (gNode B, gNB) that supports NR, and communication device 3 is a base station (evolved node B, eNode B, eNB) that supports LTE. In this embodiment, communication device 2 acts as the first communication device, and communication device 3 acts as the second communication device.

[0018] In Figure 2, the communication device 2 comprises a wireless communication unit 21, a position estimation unit 22, a beam control unit 23, a storage unit 24, a communication switching determination unit 25, a processing unit 26, and an interface communication unit 27.

[0019] The wireless communication unit 21 communicates wirelessly with the terminal device 4 using beamforming. The wireless communication unit 21 also receives measurement reports regarding the communication environment and requests for voice services from the terminal device 4. The measurement report may be a measurement report regarding the communication environment between the terminal device 4 and the communication device 2. The measurement report may also be a Measurement Report as defined by 3GPP. The wireless communication unit 21 may also transmit a reference signal to the terminal device 4. The measurement report received from the terminal device 4 may include the measurement results of the reference signal. The reference signal may be a Positioning Reference Signal (PRS) and a Sounding Reference Signal (SRS). The Positioning Reference Signal may be an NR PRS. For example, the measurement report received from terminal device 4 may include information identifying the cell in which terminal device 4 is located (Cell ID), the received power of the reference signal (Reference Signal Received Power, RSRP), the received quality of the reference signal (Reference Signal Received Quality, RSRQ), the difference between the time the reference signal was received by terminal device 4 and the time it was transmitted by communication device 2, and channel state information (Channel state information, CSI). The reference signal may also be called a reference signal.

[0020] The position estimation unit 22 estimates the position of terminal device 4 in the cell of communication device 2 based on the measurement report received from terminal device 4. The position estimation unit 22 may also store information regarding the estimated position of terminal device 4 or the measurement report in the storage unit 24. The position estimation unit 22 may estimate the position of terminal device 4 based on the measurement report each time the wireless communication unit 21 receives a measurement report. Alternatively, the position estimation unit 22 may periodically read the measurement report from the storage unit 24, estimate the position of terminal device 4 based on the read measurement report, and store information regarding the estimated position in the storage unit 24. Furthermore, the position estimation unit 22 may estimate the position of terminal device 4 when a request for voice service is made from terminal device 4, as described later.

[0021] The position estimation unit 22 may estimate the position of the terminal device 4 using the NR Positioning Protocol A (NRPPa) defined by 3GPP. When using NRPPa, the communication device 2 may estimate the position of the terminal device 4 according to at least one of the Enhanced Cell ID (E-CellID, E-CID) procedure, the NR E-CID procedure, or the Observed Time Difference Of Arrival (OTDOA) procedure.

[0022] When using NRPPa, the wireless communication unit 21 may transmit a reference signal to the terminal device 4 in response to a request from a core network node connected via interface 6. The core network node may be a Location Management Function (LMF). The request may be a request for location information using at least one of the following: Enhanced Cell ID (E-CellID, E-CID), NR E-CID, or Observed Time Difference Of Arrival (OTDOA). More specifically, the request may be an E-CID MEASUREMENT INITIATION REQUEST message, an OTDOA INFORMATION REQUEST message, or a POSITIONING INFORMATION REQUEST message.

[0023] Alternatively, the position estimation unit 22 may request location information of the terminal device 4 from a core network node (e.g., LMF), receive the location information of the terminal device 4 from the core network node, and estimate the location of the terminal device 4. Furthermore, the position estimation unit 22 may estimate the location of the terminal device 4 using the LTE Positioning Protocol (LPP).

[0024] The beam control unit 23 controls the beam's radiation direction and shape (e.g., beam width) according to the position estimated by the position estimation unit 22.

[0025] Specifically, the beam control unit 23 controls the beam's radiation direction so that the beam emitted from the wireless communication unit 21 is directed towards the terminal device 4. For example, the beam control unit 23 controls the beam's radiation direction by controlling the phase of the signals emitted from multiple antenna elements of the array antenna provided by the wireless communication unit 21.

[0026] Furthermore, the beam control unit 23 controls the beam width so that the beam width becomes narrower as the distance between the estimated position of the terminal device 4 and the position of the communication device 2 increases. For example, the beam control unit 23 increases the number of antenna elements used for the beam directed towards the terminal device 4 to narrow the beam width as the distance between the estimated position of the terminal device 4 and the position of the communication device 2 increases. Narrowing the beam width is equivalent to increasing the directivity of the beam and concentrating the power.

[0027] In addition, the beam control unit 23 may provide the number of antenna elements used for the beam used for communication with the terminal device 4 to the communication switching determination unit 25, which will be described later.

[0028] The memory unit 24 may store information or measurement reports regarding the location of the terminal device 4 estimated by the location estimation unit 22.

[0029] When a voice service is requested from the terminal device 4, the communication switching determination unit 25 decides whether or not to switch the communication device to which the terminal device 4 is connected, based on the location of the terminal device 4 estimated by the location estimation unit 22. For example, if the distance between the estimated location of the terminal device 4 and the location of the communication device 2 is greater than or equal to a predetermined threshold, the communication switching determination unit 25 decides to switch the communication device to which the terminal device 4 is connected from the communication device 2 to the communication device 3. For example, if the distance between the estimated location of the terminal device 4 and the location of the communication device 2 is greater than or equal to a predetermined threshold, the communication device 2 determines that the terminal device 4 is located in the cell edge area of ​​the communication device 2. In the following, the area of ​​a cell excluding the cell edge area may be referred to as the central area. When this switch is made, the voice service will be provided from the communication device 3 to the terminal device 4. Also, if the distance between the estimated location of the terminal device 4 and the location of the communication device 2 is shorter than a predetermined threshold, the communication switching determination unit 25 decides to keep the communication device to which the terminal device 4 is connected as the communication device 2. When this decision is made, the voice service will be provided from the communication device 2 to the terminal device 4. The location information of the terminal device 4 used in this decision may be read from the storage unit 24. The location information read by the communication switching determination unit 25 may be the location estimated at the time closest to the time when the terminal device 4 requested voice service.

[0030] Furthermore, a parameter that affects the beam width of the communication device 2 directed towards the terminal device 4 (for example, the number of antenna elements used to form the beam directed towards the terminal device 4) may be used as a parameter representing the distance between the position of the terminal device 4 and the position of the communication device 2. For example, the communication switching determination unit 25 may obtain the number of antenna elements used for the beam directed towards the terminal device 4 from the beam control unit 23, and if the number of antenna elements is equal to or greater than a predetermined threshold, it may decide to switch the communication device to which the terminal device 4 is connected from communication device 2 to communication device 3. Alternatively, if the number of antenna elements used for the beam directed towards the terminal device 4 is less than a predetermined threshold, the communication switching determination unit 25 may decide to keep the communication device to which the terminal device 4 is connected as communication device 2.

[0031] The processing unit 26 performs various processes according to the decision of the communication switching determination unit 25. For example, if the communication switching determination unit 25 decides to switch the communication device to which the terminal device 4 is connected, the processing unit 26 performs the process of switching the communication device. This process may be, for example, a fallback or an intersystem handover. This fallback may be, for example, an EPS fallback. Methods for implementing an EPS fallback include, for example, a handover and redirection, but either one may be used.

[0032] A handover is a process that switches communication devices while maintaining the connection between terminal device 4 and the network. This handover is sometimes also called an Inter-Radio-Telecommunications Handover (Inter-RAT Handover). If communication device 2 is a base station using NR, communication device 2 communicates with the core network node (e.g., AMF) through interface 5, which will be described later, and performs the Handover Preparation procedure defined by the NG interface, for example. Subsequently, communication device 2 performs the Radio Resource Control (RRC) Handover procedure to connect terminal device 4 to communication device 3. In this case, communication device 3 is a base station using LTE.

[0033] Redirection is a process in which the connection between terminal device 4 and the network is temporarily disconnected, and then communication is resumed at the destination communication device (in this case, communication device 3) according to a reconnection request from terminal device 4 (e.g., RRC Release procedure and RRC Re-establishment procedure). Redirection is sometimes referred to as RAT fallback.

[0034] Furthermore, if the communication switching determination unit 25 determines, for example, that the communication device 2 will provide voice services to the terminal device 4, the processing unit 26 will provide voice services to the terminal device 4.

[0035] The interface communication unit 27 is connected to the communication device 3 via interface 5. It is also connected to a higher-level device via interface 6. The higher-level device may be a core network node such as a Mobile Management Entity (MME) or AMF. The interface communication unit 27 also communicates with other network nodes, such as the communication device 3 or the higher-level device, through various interfaces.

[0036] In Figure 3, the communication device 3 comprises a wireless communication unit 31, a processing unit 32, and an interface communication unit 33.

[0037] The interface communication unit 33 is configured similarly to the interface communication unit 27 in the communication device 2. The interface communication unit 33 is connected to the communication device 2 through interface 5 and also to a higher-level device through interface 6.

[0038] The wireless communication unit 31 connects to the terminal device 4 by switching the above-mentioned communication devices (for example, fallback or intersystem handover). The wireless communication unit 31 connects to the terminal device 4 using wireless communication technology and communicates with it. This wireless communication technology may be LTE or NR.

[0039] The processing unit 32 provides a voice service to the terminal device 4 in accordance with a request for the provision of a voice service received from the host device 100. The processing unit 32 may also provide a voice service to the terminal device 4 in accordance with a request for the provision of a voice service received from the terminal device 4 via the host device 100.

[0040] Terminal device 4 transmits a measurement report regarding the communication environment with the communication device to the connected communication device. For example, if terminal device 4 is connected to communication device 2, terminal device 4 may measure the communication environment with communication device 2 and transmit a measurement report of the communication environment to communication device 2. In addition, terminal device 4 may perform measurements regarding the communication environment with communication device 3 and transmit a measurement report regarding the communication environment with communication device 3 to the connected communication device 2. Furthermore, terminal device 4 may transmit measurement reports periodically or on an event-by-event basis. For example, terminal device 4 may transmit a measurement report to communication device 2 in response to a request from communication device 2. Also, terminal device 4 may transmit a measurement report to communication device 2 in response to the reception of a reference signal from communication device 2. For example, terminal device 4 may transmit a measurement report to the connected communication device 2 whenever the connection status between terminal device 4 and communication device 2 or between terminal device 4 and communication device 3 changes.

[0041] Next, an example of the operation of the communication device 2 according to the first embodiment will be described using Figure 4. Figure 4 is a flowchart showing an example of the operation of the communication device 2 according to the first embodiment.

[0042] The wireless communication unit 21 of the communication device 2 receives a measurement report from the terminal device 4 (S101). The position estimation unit 22 of the communication device 2 estimates the position of the terminal device 4 based on the measurement report (S102). The wireless communication unit 21 of the communication device 2 receives a voice service request from the terminal device 4 (S103). The communication switching determination unit 25 of the communication device 2 determines, based on the position of the terminal device 4 estimated by the position estimation unit 22, whether the terminal device 4 is in the central area of ​​the communication device 2 or in the cell edge area (S104). If the terminal device 4 is in the cell edge area, the communication switching determination unit 25 of the communication device 2 determines to perform a switch on the communication device to which the terminal device 4 is connected (S105). The processing unit 26 of the communication device 2 performs the switching process for the communication device to which the terminal device 4 is connected (S106). The communication switching determination unit 25 of the communication device 2 determines that if the terminal device 4 is in the central area of ​​the cell, it will not switch the communication device to which the terminal device 4 is connected, and will provide voice service to the communication device 2 (S107). The processing unit 26 of the communication device 2 provides voice service to the terminal device 4 (S108).

[0043] Naturally, the above operations may be performed individually or in combination as appropriate. Through the above operations, communication device 2 can determine whether to switch communication devices according to the position of terminal device 4. For example, if terminal device 4 is in the center of the cell, no switching of the communication device to which terminal device 4 is connected will be performed, but if terminal device 4 is at the edge of the cell, the switching process for the communication device to which terminal device 4 is connected will be performed. It is thought that terminal devices at the edge of the cell are less likely to fail in the switching process to communication device 3 compared to terminal devices at the center of the cell of communication device 2. This is because terminal devices at the edge of the cell are closer to communication device 3 and are therefore considered to have higher communication quality with communication device 3 compared to terminal devices at the center of the cell of communication device 2. Therefore, it is possible to control the switching of communication devices while reducing the load on the network.

[0044] <Second Embodiment> Figure 5 shows an image diagram of the multiple cells 70-1, 70-2, and 70-3 provided by the communication device 7 in this embodiment, and Figure 6 shows an example of the configuration of the communication device 7 in this embodiment. The communication device 7 corresponds to the communication device 2 in the first embodiment, and the communication device 8 corresponds to the communication device 3 in the first embodiment. The terminal device 9 corresponds to the terminal device 4 in the first embodiment. Also, the interface 10 corresponds to the interface 5 in the first embodiment.

[0045] In Figure 6, the communication device 7 includes a cell location information storage unit 71 and a communication switching determination unit 72. The cell location information storage unit 71 stores the location information of multiple cells provided by the communication device 7. This location information may be information indicating the tracking area (TA) to which the cell belongs, or information indicating the RAN notification area (RNA), as defined by 3GPP.

[0046] When a voice service is requested from a terminal device 9, the communication switching determination unit 72 decides whether or not to switch the communication device to which the terminal device 9 is connected, based on the location of the cell where the terminal device 9 is located. For example, the communication device 7 provides several cells 70-1, 70-2, and 70-3 that are at different distances from the communication device 7. When the communication device 7 receives a voice service request from a terminal device 9, the communication switching determination unit 72 reads information from the cell location information storage unit 71 regarding the location of the cell where the terminal device 9 is located (camp on). The communication switching determination unit 72 then decides whether or not to switch the communication device based on the distance of the cell where the terminal device 9 is located from the communication device 7. For example, if the distance between a particular cell and the communication device 7 is greater than or equal to a predetermined threshold, the communication switching determination unit 72 decides not to provide voice service in that cell. When a voice service is requested from the terminal device 9, the communication switching determination unit 72 decides to change the communication device to which the terminal device 9 is connected from the communication device 7 to the communication device 8. For example, if the distance between a specific cell and the communication device 7 is below a predetermined threshold, the communication switching determination unit 72 decides to provide voice service in that cell. Then, when voice service is requested from the terminal device 9, the communication device 7 provides the voice service to the terminal device 9. The communication switching determination unit 72 may also determine whether or not to switch the communication device for each TA or RNA to which the cell belongs. More specifically, the communication switching determination unit 72 may grasp information regarding the location of the TA or RNA to which the cell belongs and make a decision to switch the communication device based on that information regarding the location of the TA or RNA. Alternatively, the communication switching determination unit 72 may decide in advance whether or not to switch the communication device for each TA or RNA and make a decision to switch the communication device based on that decision.

[0047] Next, an example of the operation of the communication device 7 in the second embodiment will be described using Figure 7. Figure 7 is a flowchart showing an example of the operation of the communication device 7 according to the second embodiment.

[0048] The cell location information storage unit 71 of the communication device 7 records information about the location of each cell (S201). The communication switching determination unit 72 of the communication device 7 reads the cell location information from the cell location information storage unit 71 and, when a voice service is requested from the terminal device, determines whether or not to switch communication devices based on the location of the cell where the terminal device is located (S202). The communication device 7 receives a voice service request from the terminal device 9 (S203). The communication switching determination unit 72 of the communication device 7 identifies the cell where the terminal device 9 is located (S204). The communication switching determination unit 72 of the communication device 7 determines whether or not to switch communication devices based on the information about the location of the cell (S205). If the communication device is to be switched (S205, YES), the communication device 7 performs the process of switching the communication device that will provide voice service to the terminal device 9 to the communication device 8 (S206). If the communication device is not to be switched (S205, NO), the communication device 7 provides voice service to the terminal device 9 (S207).

[0049] This allows the communication device 7 to perform a communication device switch when the terminal device 4 is located in a cell that is subject to communication device switching. Therefore, it becomes possible to reduce the processing load on the communication device 7 associated with communication device switching.

[0050] <Third Embodiment> Figure 8 shows an example of the configuration of the communication device 11 in this embodiment. The communication device 11 corresponds to the communication device 2 in the first embodiment. The communication device 12 in the following description corresponds to the communication device 3 in the first embodiment. The terminal device 13 in the following description corresponds to the terminal device 4 in the first embodiment. Note that the communication device 11 and the communication device 12 may each support different wireless communication methods.

[0051] In Figure 8, the communication device 11 includes an acquisition unit 111 and a communication switching determination unit 112. The acquisition unit 111 acquires, for example, an index related to the distance between the communication device 11 and the terminal device 13. The distance-related index may be the position of the terminal device 13, as in the first embodiment, or it may be a parameter that affects the beam width of the communication device 11 directed towards the terminal device 13 (for example, the number of antenna elements used for the beam directed towards the terminal device 13). Alternatively, the distance-related index may be the position of the cell where the terminal device 13 is located (camp on), as in the second embodiment.

[0052] The communication switching determination unit 112, for example, when a voice service is requested from the terminal device 13, determines whether to switch the communication device providing voice service to the terminal device 13 from communication device 11 to communication device 12 based on the index acquired by the acquisition unit 111. For example, if the index corresponds to a distance longer than a predetermined threshold, the communication switching determination unit 112 decides to switch the communication device providing voice service to the terminal device 13 from communication device 11 to communication device 12. If the index corresponds to a distance less than or equal to a predetermined threshold, the communication switching determination unit 112 decides to keep the communication device providing voice service to the terminal device 13 as communication device 11 without switching from communication device 11 to communication device 12.

[0053] Next, an example of the operation of the communication device 11 according to the third embodiment will be described using Figure 9. Figure 9 is a sequence diagram showing an example of the operation of the communication device 11 according to the third embodiment.

[0054] The acquisition unit 111 of the communication device 11 acquires an index related to the distance between the communication device 11 and the terminal device 13 (S301). When the terminal device 13 requests a voice service, the communication switching determination unit 112 of the communication device 11 determines, based on the index acquired by the acquisition unit 111, whether or not to switch the communication device that provides the voice service to the terminal device 13 from the communication device 11 to the communication device 12 (S302). As a result, the communication device 11 can switch the communication device that provides the voice service to the terminal device 13 based on the distance index between the communication device 11 and the terminal device 13. Therefore, it becomes possible to reduce the processing load on the communication device 11 associated with switching communication devices.

[0055] <Fourth Embodiment> Figure 10 shows an example of the configuration of the communication device 14 in this embodiment. The communication device 14 corresponds to the communication device 2 in the first embodiment. The communication device 15 in the following description corresponds to the communication device 3 in the first embodiment. The terminal device 16 in the following description corresponds to the terminal device 4 in the first embodiment. In the following description, in order to simplify the explanation, we will describe an example where there is one target terminal device, the communication device 14 is a base station (gNode B, gNB) that supports NR, and the communication device 15 is a base station (evolved node B, eNode B, eNB) that supports LTE.

[0056] In Figure 10, the communication device 14 includes a wireless communication unit 141, a communication quality acquisition unit 142, a storage unit 143, a communication switching determination unit 144, a processing unit 145, and an interface communication unit 146.

[0057] The wireless communication unit 141 corresponds to the wireless communication unit 21 of the communication device 2 in the first embodiment. The wireless communication unit 141 communicates wirelessly with the terminal device 16 using beamforming. The wireless communication unit 141 also receives measurement reports regarding the communication environment and requests for voice services from the terminal device 16.

[0058] The communication quality acquisition unit 142 acquires "indicators related to the communication quality of the terminal device 16." For example, the communication quality acquisition unit 142 may acquire predetermined information as "indicators related to the communication quality of the terminal device 16" from the measurement report received from the terminal device 16. In other words, the communication quality acquisition unit 142 of the communication device 14 may acquire these indicators on a per-terminal device basis. Alternatively, the communication quality acquisition unit 142 may acquire these indicators each time it receives a measurement report from the terminal device 16.

[0059] For example, the information included in the measurement report received from the terminal device 16 and acquired by the communication quality acquisition unit 142 as an "indicator of the communication quality of the terminal device 16" may be at least one of the following: information identifying the cell in which the terminal device 16 is located (Cell ID), Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), the difference between the time the reference signal is received by the terminal device 16 and the time it is transmitted by the communication device 14, and Channel state information (CSI).

[0060] The storage unit 143 stores at least one of the above-mentioned measurement report or the "indicators related to the communication quality of the terminal device 16". If there are multiple terminal devices communicating with the communication device 14, the storage unit 43 may store the above-mentioned measurement report and the "indicators related to the communication quality of the terminal device 16" for each terminal device.

[0061] When a voice service is requested from the terminal device 16, the communication switching determination unit 144 decides whether or not to switch the communication device to which the terminal device 16 is connected, based on, for example, the "indicators related to the communication quality of the terminal device 16" acquired by the communication quality acquisition unit 142.

[0062] For example, if the communication switching determination unit 144 indicates that the "indicator of communication quality of terminal device 16" is below a predetermined level, it decides to switch the communication device to which terminal device 16 is connected from communication device 14 to communication device 15. Once this switch is made, the voice service will be provided to terminal device 4 from communication device 15. For example, if the "indicator of communication quality of terminal device 16" indicates that the communication quality is above a predetermined level, the communication switching determination unit 144 decides to keep the communication device to which terminal device 16 is connected as communication device 14. For example, if at least one of the RSRP or RSRQ of the reference signal in the "indicator of communication quality of terminal device 16" is below a predetermined threshold, the communication switching determination unit 144 may decide to switch the communication device to which terminal device 16 is connected from communication device 14 to communication device 15. Furthermore, for example, the communication switching determination unit 144 may decide to keep the communication device to which the terminal device 16 is connected as the communication device 14 if at least one of the RSRP or RSRQ reference signals among the "indicators related to the communication quality of the terminal device 16" is above a predetermined threshold.

[0063] The processing unit 145 corresponds to the processing unit 26 of the communication device 2 in the first embodiment. That is, the processing unit 145 performs various processes according to the decision of the communication switching determination unit 144. For example, if the communication switching determination unit 144 decides to switch the communication device to which the terminal device 16 is connected, the processing unit 145 performs the process of switching the communication device. Also, for example, if the communication switching determination unit 144 decides not to switch the communication device to which the terminal device 16 is connected and that the communication device 14 will provide voice services to the terminal device 16, the processing unit 145 provides voice services to the terminal device 16. The interface communication unit 146 is configured similarly to the interface communication unit 27 of the communication device 2 in the first embodiment. The interface communication unit 146 is connected to the communication device 15 through an interface and is also connected to a higher-level device through another interface.

[0064] Next, an example of the operation of the communication device 14 according to the fourth embodiment will be described using Figure 11. Figure 11 is a flowchart showing an example of the operation of the communication device 14 according to the fourth embodiment.

[0065] The wireless communication unit 141 of the communication device 14 receives a measurement report from the terminal device 16 (S401). The communication quality acquisition unit 142 of the communication device 14 acquires an index related to the communication quality of the terminal device 16 from the received measurement report (S402). The wireless communication unit 141 of the communication device 14 receives a request for voice service from the terminal device 16 (S403). The communication switching determination unit 144 of the communication device 14 determines whether or not to switch the communication device that provides voice service to the terminal device 16 based on the index related to the communication quality of the terminal device 16 acquired by the communication quality acquisition unit 142 (S404). The communication switching determination unit 144 of the communication device 14 determines whether or not to switch the communication device that provides voice service to the terminal device 16 if the index related to the communication quality of the terminal device 16 is at a predetermined level. less than If the communication quality is such that the terminal device 16 is connected to a certain level or higher, the system determines that it will switch the communication device to which the terminal device 16 is connected (S405). The processing unit 145 of the communication device 14 performs the switching process for the communication device to which the terminal device 16 is connected (S406). The communication switching determination unit 144 of the communication device 14 determines that if the indicator for the communication quality of the terminal device 16 is at or above a predetermined level, it will not switch the communication device to which the terminal device 16 is connected and will provide the voice service (S407). The processing unit 145 of the communication device 14 provides the voice service to the terminal device 16 (S408).

[0066] Through the operations described above, the communication device 14 can determine whether to switch communication devices according to the communication quality with the terminal device 16. For example, if the communication quality between the terminal device 16 and the communication device 14 is good, the communication device will not be switched to provide voice service to the terminal device 16. For example, if the communication quality between the terminal device 16 and the communication device 14 is poor, the communication device will be switched to provide voice service to the terminal device 16. This makes it possible to control the switching of communication devices while reducing the network load.

[0067] <Modified form of the fourth embodiment> <1> The "indicator of communication quality of terminal device 16" acquired by the communication quality acquisition unit of communication device 14 may be the number of wireless reconnections performed by terminal device 16 with communication device 14.

[0068] More specifically, the communication quality acquisition unit 142 may acquire the number of wireless reconnection operations performed by the terminal device 16 with the communication device 14. The number of wireless reconnection operations may be, for example, at least one of the following: the number of RRC failure procedures and RRC Re-establishment procedures performed between the communication device 14 and the terminal device 16, or the number of intersystem handover or fallback operations performed from the communication device 14 to the communication device 15.

[0069] For example, if the number of wireless reconnection attempts described above is above a predetermined threshold, the communication switching determination unit 144 may decide to switch the communication device to which the terminal device 16 is connected from communication device 14 to communication device 15. For example, if the number of wireless reconnection attempts described above is below a predetermined threshold, the communication switching determination unit 144 may decide to keep the communication device to which the terminal device 16 is connected as communication device 14.

[0070] <2> As an indicator of the communication quality of the terminal device 16, the communication quality acquisition unit 142 may acquire the number of times an intersystem handover or fallback failed among past attempts to switch between the terminal device 16 and the communication device 15 from the communication device 14. For example, if the number of failed intersystem handovers or fallbacks is below a predetermined threshold, the communication switching determination unit 144 may decide to keep the communication device to which the terminal device 16 is connected as communication device 14. For example, if the number of failed intersystem handovers or fallbacks is above a predetermined threshold, the unit may decide to switch the communication device to which the terminal device 16 is connected from communication device 14 to communication device 15.

[0071] <3> The "indicators related to the communication quality of the terminal device 16" described above may be used in any combination. For example, the communication switching determination unit 144 may determine whether or not to switch the communication device to which the terminal device 16 is connected from communication device 14 to communication device 15 by combining the number of times an intersystem handover or fallback failed in past attempts from communication device 14 to communication device 15 with the reference signal RSRP or RSRQ. For example, even if the reference signal RSRP or RSRQ is below a predetermined threshold, if the number of times an intersystem handover or fallback failed is above a predetermined threshold, the communication switching determination unit 144 may decide to keep the communication device to which the terminal device 16 is connected as communication device 14.

[0072] <4> In the fourth embodiment and its modifications described above, the communication device 14 acquires indicators related to the communication quality with the terminal device on a per-terminal device basis and switches the communication device that provides voice service to the terminal device. On the other hand, the communication quality acquisition unit 142 may acquire "indicators related to the communication quality of the cell." In other words, the communication quality acquisition unit 142 may acquire indicators related to the communication quality on a per-cell basis.

[0073] For example, the "indicator of cell communication quality" may be a statistically processed result of the "indicator of terminal device communication quality" across multiple terminal devices. For instance, the communication quality acquisition unit 142 may acquire the average value of the RSRP and RSRQ reference signals included in measurement reports from multiple terminal devices located in a specific cell as the "indicator of cell communication quality." Alternatively, the communication quality acquisition unit 142 may calculate the total number of wireless reconnection attempts by multiple terminal devices in a specific cell and acquire this as the "indicator of cell communication quality."

[0074] More specifically, the communication quality acquisition unit 142 of the communication device 14 may acquire "indicators related to the communication quality of terminal devices" from each of the multiple terminal devices and record them in the storage unit 143. The communication quality acquisition unit 142 may then read the "indicators related to the communication quality of terminal devices" from the storage unit 143 and acquire "indicators related to the communication quality of cells" by statistically processing these indicators. The communication quality acquisition unit 142 may acquire "indicators related to the communication quality of cells" periodically, or it may acquire "indicators related to the communication quality of cells" whenever the "indicators related to the communication quality of terminal devices" are updated.

[0075] When a terminal device connected to the communication device 14 requests a voice service, the communication switching determination unit 144 may decide whether or not to switch the communication device to which the terminal device is connected, based on the "indicators related to the communication quality of the cell" acquired by the communication quality acquisition unit 142.

[0076] For example, if the average of the RSRP and RSRQ of the reference signals included in the measurement reports from multiple terminal devices located in a particular cell is above a predetermined threshold, the communication switching determination unit 144 may decide to keep the communication device to which terminal device 16 is connected as communication device 14. For example, if the average of the RSRP and RSRQ of the reference signals included in the measurement reports from multiple terminal devices located in a particular cell is below a predetermined threshold, the communication switching determination unit 144 may decide to switch the communication device to which terminal device 16 is connected from communication device 14 to communication device 15.

[0077] For example, if the total number of wireless reconnection attempts by multiple terminal devices in a particular cell exceeds a predetermined threshold, the communication switching determination unit 144 may decide to switch the communication device to which terminal device 16 is connected from communication device 14 to communication device 15.

[0078] For example, if the total number of wireless reconnection attempts by multiple terminal devices in a particular cell is below a predetermined threshold, the communication switching determination unit 144 may decide to keep the communication device to which the terminal device 16 is connected as communication device 14. Through the above operation, the communication device 14 can determine whether to switch communication devices according to the communication quality of each cell. For example, if the communication quality of the cell in which the terminal device 16 is located is good, the communication device that provides that cell and provides voice services to the terminal device will not be switched. For example, if the communication quality of the cell in which the terminal device 16 is located is poor, the communication device that provides voice services to the terminal device 16 will be switched to provide voice services. This makes it possible to control the switching of communication devices while reducing the load on the network.

[0079] <Other Embodiments> The communication devices 2, 3, 7, 8, 11, 12, 14, 15 and terminal devices 4, 9, 13, 16 (hereinafter referred to as communication device 1003, etc.) according to the above-described embodiment may have the following hardware configuration. Figure 12 is a block diagram illustrating the hardware configuration of a computer (information processing device) capable of realizing each embodiment of the communication device.

[0080] Referring to Figure 12, the communication device 1003, etc., includes a network interface 1000, a processor 1001, and memory 1002. The network interface 1000 is used to communicate with other wireless communication devices, including multiple communication terminals. The network interface 1000 may include, for example, a network interface card (NIC) compliant with the IEEE 802.11 series, IEEE 802.3 series, etc.

[0081] The processor 1001 reads and executes software (computer programs) from the memory 1002 to perform processing on the communication device 1003, etc., as described using flowcharts and sequence diagrams in the above embodiment. The processor 1001 may be, for example, a microprocessor, an MPU (Micro Processing Unit), or a CPU (Central Processing Unit). The processor 1001 may include multiple processors.

[0082] Memory 1002 is composed of a combination of volatile and non-volatile memory. Memory 1002 may also include storage located away from the processor 1001. In this case, the processor 1001 may access memory 1002 via an I / O interface (not shown).

[0083] In the example shown in Figure 12, memory 1002 is used to store a group of software modules. The processor 1001 can read these software modules from memory 1002 and execute them, thereby enabling the communication device 1003 and other processes described in the above embodiment.

[0084] As explained using Figure 12, each processor in the communication device 1003, etc., executes one or more programs that include a set of instructions for causing the computer to perform the algorithm described in the diagram.

[0085] In the above example, the program can be stored and supplied to the computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable medium includes various types of tangible storage media. Examples of non-transitory computer-readable medium include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives) and magneto-optical storage media (e.g., magneto-optical disks). Furthermore, examples of non-transitory computer-readable medium include CD-ROM (Read Only Memory), CD-R, and CD-R / W. Further examples of non-transitory computer-readable medium include semiconductor memory. Semiconductor memory includes, for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, and RAM (Random Access Memory). In addition, the program may be supplied to the computer by various types of transient computer-readable medium. Examples of transient computer-readable medium include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable media can supply programs to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0086] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. Furthermore, this disclosure may be implemented by combining the respective embodiments as appropriate.

[0087] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0088] (Note 1) A first communication device, An acquisition means for acquiring an indicator related to the distance between the first communication device and the terminal device, A communication switching determination means that, when a voice service is requested from the terminal device, determines, based on the indicator, whether or not to switch the communication device that provides the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, Having, The first communication device.

[0089] (Note 2) The communication switching determination means determines, when the indicator corresponds to a distance longer than a predetermined threshold, to switch the communication device providing the voice service to the terminal device from the first communication device to the second communication device. The first communication device described in Appendix 1.

[0090] (Note 3) The communication switching determination means determines, when the indicator corresponds to the distance being less than or equal to the predetermined threshold, that the communication device providing the voice service to the terminal device will remain the first communication device without switching from the first communication device to the second communication device. The first communication device described in Appendix 2.

[0091] (Note 4) The aforementioned index is the number of antenna elements used to form a beam used for communication with the terminal device. The first communication device described in any one of the items 1 to 3 of the appendix.

[0092] (Note 5) The acquisition means is, A wireless communication means for receiving measurement reports from the terminal device, A position estimation means for estimating the position of the terminal device as an indicator from the measurement report, Equipped with, The first communication device described in any one of the items 1 to 3 of the appendix.

[0093] (Note 6) The wireless communication means transmits a reference signal to the terminal device and receives the measurement report of the reference signal from the terminal device. The first communication device described in Appendix 5.

[0094] (Note 7) The aforementioned reference signal is a positioning reference signal or a sounding reference signal. The first communication device described in Appendix 6.

[0095] (Note 8) The wireless communication means transmits the reference signal to the terminal device in response to a request from a core network node connected to the first communication device. The first communication device as described in either item 6 or 7 of the appendix.

[0096] (Note 9) The measurement report includes at least one of the following: information identifying the cell in which the terminal device is located, the received power of the reference signal, and the received quality of the reference signal. The first communication device described in any one of the items 6 to 8 of the appendix.

[0097] (Note 10) The measurement report transmitted by the aforementioned terminal device is a Measurement Report. The first communication device described in any one of the items 5 to 9 of the appendix.

[0098] (Note 11) If the communication switching determination means determines that the communication device providing the voice service to the terminal device will be switched from the first communication device to the second communication device, it will perform an intersystem handover or fallback process. The first communication device described in any one of the appendices 1 to 10.

[0099] (Note 12) The aforementioned fallback is EPS fallback. The first communication device described in Appendix 11.

[0100] (Note 13) The first communication device is a base station that supports New Radio (NR), and the second communication device is a base station that supports Long Term Evolution (LTE). The first communication device described in any one of the appendices 1 to 12.

[0101] (Note 14) The voice service provided by the first communication device is Voice over NR (VoNR), and the voice service provided by the second communication device is Voice over LTE (VoLTE). The first communication device described in any one of the appendices 1 to 13.

[0102] (Note 15) A method performed by a first communication device, An index related to the distance between the first communication device and the terminal device is obtained, When a voice service is requested from the terminal device, the system determines whether to switch the communication device providing the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, based on the indicator. A method for the first communication device.

[0103] (Note 16) The first communication device, An index related to the distance between the first communication device and the terminal device is obtained, When a voice service is requested from the terminal device, the system determines whether to switch the communication device providing the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, based on the indicator. A computer-readable recording medium that contains a program to execute a process.

[0104] This application claims priority based on Japanese Patent Application No. 2022-055429, filed on 30 March 2022, and incorporates all of its disclosures herein. [Explanation of symbols]

[0105] 1 Network 2, 3, 7, 8, 11, 12, 14, 15 Communication devices 4, 9, 13, 16 Terminal devices 5, 6, 10 Interfaces 20 cells 21 Wireless Communication Section 22 Position estimation part 23 Beam Control Unit 24 Memory section 25 Communication switching determination unit 26 Processing Unit 27 Interface Communication Unit 30 cells 31 Wireless Communication Section 32 Processing Units 33 Interface Communication Unit Cells 70-1, 70-2, and 70-3 71 Cell position information storage unit 72 Communication switching determination unit 111 Acquisition Department 112 Communication switching determination unit 141 Wireless Communication Section 142 Communication Quality Acquisition Unit 143 Storage section 144 Communication switching determination unit 145 Processing Unit 146 Interface Communication Unit 1000 Network Interfaces 1001 Processor 1002 memory 1003 Communication device

Claims

1. A first communication device, An acquisition means for acquiring an indicator related to the distance between the first communication device and the terminal device, A communication switching determination means, when a voice service is requested from the terminal device, determines, based on the indicator, whether or not to switch the communication device that provides the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, It has, The first communication device, wherein the index is the number of antenna elements used to form a beam used for communication with the terminal device.

2. The communication switching determination means determines, when the indicator corresponds to a distance longer than a predetermined threshold, to switch the communication device providing the voice service to the terminal device from the first communication device to the second communication device. The first communication device according to claim 1.

3. The communication switching determination means determines, when the indicator corresponds to the distance being less than or equal to the predetermined threshold, that the communication device providing the voice service to the terminal device will remain the first communication device without switching from the first communication device to the second communication device. The first communication device according to claim 2.

4. A method performed by a first communication device, An index related to the distance between the first communication device and the terminal device is obtained, When a voice service is requested from the terminal device, a decision is made based on the indicator as to whether or not to switch the communication device that provides the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device. The aforementioned index is the number of antenna elements used to form a beam used for communication with the terminal device. A method for a first communication device.

5. In the first communication device, An index related to the distance between the first communication device and the terminal device is obtained, When a voice service is requested from the terminal device, the system determines whether to switch the communication device providing the voice service to the terminal device from the first communication device to a second communication device that uses a different wireless communication method than the first communication device, based on the indicator. Execute the process, The program wherein the index is the number of antenna elements used to form a beam used for communication with the terminal device.

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