Relaxation of roaming connection restrictions during normal times

Abstract

A communication control device according to the present invention comprises at least one processor which: causes a roaming restriction area setting unit to set a roaming restriction area where roaming connections are restricted at normal times and where roaming connections are allowed in an emergency; and causes a roaming restriction easing unit to ease the restriction on roaming connections at normal times for a specific communication cell included in the roaming restriction area. The roaming restriction area includes a plurality of communication cells. The roaming restriction area includes a terrestrial communication cell provided on the ground by a terrestrial base station installed on the ground, and a non-terrestrial communication cell provided on the ground by a flying non-terrestrial base station. The roaming restriction easing unit eases the restriction on roaming connections at normal times for the non-terrestrial communication cell included in the roaming restriction area. The non-terrestrial base station is a communication satellite flying in outer space.

Description

[Technical Field]

[0001] The present disclosure relates to relaxing restrictions on roaming connections during normal times. [Background technology]

[0002] The number, types, and uses of wireless communication devices (hereinafter referred to collectively as communication devices), such as smartphones and IoT (Internet of Things) devices, are steadily increasing, and wireless communication standards are continually being expanded and improved. For example, commercial service for the fifth-generation mobile communication system, known as "5G," began in 2018, and standardization is still underway at the Third Generation Partnership Project (3GPP). In addition, efforts have begun to develop standards for "6G," or sixth-generation mobile communication systems, as the next-generation wireless communication standard following 5G.

[0003] Patent Document 1 discloses a network selection technique for so-called disaster roaming. In disaster roaming, roaming connection to a specific roaming network is permitted only when the home network becomes unavailable during a disaster. Under normal circumstances, roaming connection to the specific roaming network is prohibited. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2022 / 0264275 Summary of the Invention [Problem to be solved by the invention]

[0005] Connection settings for disaster roaming are rigid, and even if there are sufficient communication resources available for roaming communication in a roaming network, they will go unused and wasted during normal times.

[0006] The present disclosure has been made in consideration of such circumstances, and provides a communication control device and the like that can relax restrictions on roaming connections during normal times. [Means for solving the problem]

[0007] A communication control device according to one aspect of the present disclosure includes at least one processor that executes the following: a roaming restricted area setting unit that sets a roaming restricted area in which roaming connections are restricted under normal circumstances and roaming connections are permitted under emergency circumstances; and a roaming restriction relaxation unit that relaxes the restrictions on roaming connections under normal circumstances for specific communication cells included in the roaming restricted area.

[0008] According to this aspect, it is possible to relax the restrictions on roaming connections during normal times for a specific communication cell included in a roaming restricted area in which roaming connections are restricted except in emergencies.

[0009] Another aspect of the present disclosure is a communication control method that sets a roaming restricted area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies, and relaxes the restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area.

[0010] Yet another aspect of the present disclosure is a storage medium storing a communication control program that causes a computer to set a roaming restricted area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies, and to relax the restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area.

[0011] Any combination of the above components, or any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc., are also encompassed within the present disclosure. [Effects of the Invention]

[0012] According to the present disclosure, restrictions on roaming connections can be relaxed during normal times. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows a schematic overview of a wireless communication system to which a communication control device is applied. [Figure 2] FIG. 2 is a functional block diagram illustrating a communication control device. [Figure 3] 10 is a flowchart illustrating an example of communication control by a communication control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, with reference to the drawings, a detailed description will be given of a mode for carrying out the present disclosure (hereinafter also referred to as an embodiment). In the description and / or drawings, identical or equivalent components, members, processes, etc. are designated by the same reference numerals, and redundant description will be omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the description and should not be interpreted as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present disclosure in any way. Not all features and their combinations presented in the embodiment are necessarily essential to the present disclosure. For convenience, the embodiment is presented broken down into components for each function and / or functional group that realizes the feature. However, one component in the embodiment may actually be realized by a combination of multiple separate components, or multiple components in the embodiment may actually be realized by a single integrated component.

[0015] The communication control device according to this embodiment can be applied to a terrestrial network (TN) constructed by terrestrial communication cells provided to the ground by terrestrial base stations installed on the ground, a non-terrestrial network (NTN) constructed by non-terrestrial communication cells provided to the ground by airborne non-terrestrial base stations, and a network in which TNs and NTNs coexist. These base stations and / or communication cells may belong to the same mobile communication network, public land mobile network (PLMN), mobile network operator (MNO), or mobile virtual network operator (MVNO), or may belong to different mobile communication networks, PLMNs, MNOs, or MVNOs. Hereinafter, mobile communication networks, PLMNs, MNOs, and MVNOs are collectively referred to as PLMNs.

[0016] FIG. 1 schematically illustrates an overview of a wireless communication system 1 to which a communication control device according to an embodiment of the present disclosure is applied. The wireless communication system 1 includes a 5G wireless communication system 11, a 4G wireless communication system 12, and a satellite communication system 13. The 5G wireless communication system 11 conforms to a fifth-generation mobile communication system (5G) that uses NR (New Radio) or 5G NR (Fifth Generation New Radio) as a radio access technology (RAT) and 5GC (Fifth Generation Core) as a core network (CN). The 4G wireless communication system 12 conforms to a fourth-generation mobile communication system (4G) that uses LTE (Long Term Evolution) or LTE-Advanced as a radio access technology and EPC (Evolved Packet Core) as a core network. The satellite communication system 13 is responsible for satellite communication via a communication satellite 131. Although not shown in the figures, the wireless communication system 1 may include a wireless communication system of a generation earlier than 4G, a wireless communication system of a generation later than 5G (such as 6G), or any wireless communication system that is not associated with a generation such as Wi-Fi (registered trademark). Furthermore, the wireless communication system 1 may not include some or all of the 5G wireless communication system 11, the 4G wireless communication system 12, and the satellite communication system 13.

[0017] The 5G wireless communication system 11 includes communication devices 2A, 2B, 2C, and 2D (hereinafter collectively referred to as communication devices 2) such as smartphones that are installed on the ground and are also called UE (User Equipment), and multiple 5G base stations 111A, 111B, and 111C (hereinafter collectively referred to as 5G base stations 111) that can communicate via 5G NR. In 5G, the base station 111 is also called a gNodeB (gNB). The communication range or support area of ​​each of the 5G base stations 111A, 111B, and 111C is called a cell, and is illustrated as 112A, 112B, and 112C, respectively (hereinafter collectively referred to as 5G cells 112).

[0018] The size of the 5G cell 112 of each 5G base station 111 is arbitrary, but typically ranges from a few meters to tens of kilometers in radius. Although there is no established definition, cells with a radius of a few meters to tens of meters are called femtocells, cells with a radius of tens to tens of meters are called picocells, cells with a radius of tens to hundreds of meters are called microcells, and cells with a radius of more than hundreds of meters are called macrocells. 5G often uses high-frequency radio waves such as millimeter waves, and because of their high line-propagation ability, radio waves can be blocked by obstacles, shortening the communication distance. For this reason, 5G tends to use smaller cells than 4G and earlier generations.

[0019] A communication device 2 can perform 5G communication if it is located within at least one of multiple 5G cells 112A, 112B, and 112C. In the illustrated example, a communication device 2B located within 5G cells 112A and 112B can communicate with both 5G base stations 111A and 111B via 5G NR. Furthermore, a communication device 2C located within 5G cell 112C can communicate with 5G base station 111C via 5G NR. Communication devices 2A and 2D are located outside all of the 5G cells 112A, 112B, and 112C and are therefore unable to communicate via 5G NR. 5G communication via 5G NR between each communication device 2 and each 5G base station 111 is managed by the 5GC, which is a core network. For example, the 5GC handles data transmission and reception between each 5G base station 111, data transmission and reception between EPC, a satellite communication system 13, and external networks such as the Internet, and mobility management of the communication device 2.

[0020] The 4G wireless communication system 12 includes multiple 4G base stations 121 (only one is shown in FIG. 1). The multiple 4G base stations 121 are installed on the ground and are capable of communicating with the communication device 2 via LTE or LTE-Advanced. In 4G, the base station 121 is also called an eNodeB (eNB). Like each 5G base station 111, the communication range or support area of ​​each 4G base station 121 is also called a cell and is illustrated as 122.

[0021] If the communication device 2 is located inside the 4G cell 122, it can perform 4G communication. In the illustrated example, communication devices 2A and 2B located inside the 4G cell 122 can communicate with the 4G base station 121 via LTE or LTE-Advanced. Communication devices 2C and 2D are located outside the 4G cell 122 and are therefore unable to communicate via LTE or LTE-Advanced. 4G communication between each communication device 2 and each 4G base station 121 via LTE or LTE-Advanced is managed by the EPC, which is a core network. For example, the EPC handles the exchange of data with each 4G base station 121, the exchange of data with external networks such as 5GC, the satellite communication system 13, and the Internet, and the mobility management of the communication device 2.

[0022] Focusing on each of the communicators 2A, 2B, 2C, and 2D, in the illustrated example, communicator 2A is capable of 4G communication with 4G base station 121, communicator 2B is capable of 5G communication with 5G base stations 111A and 111B and 4G communication with 4G base station 121, and communicator 2C is capable of 5G communication with 5G base station 111C. In cases where there are multiple base stations (111A, 111B, 121) with which communicator 2B can communicate, one base station determined to be optimal in terms of communication quality, etc., is selected under the management of the 5G communication center (5GC) and / or EPC, which are core networks, and communicates with communicator 2B. Furthermore, communicator 2D is not capable of communication with any of the 5G base stations 111 and 4G base station 121, and therefore communicates via satellite communication system 13, which will be described next.

[0023] The satellite communication system 13 is a wireless communication system that uses a communication satellite 131, which is a low-orbit satellite flying in space at an altitude of approximately 500 km to 700 km above the Earth's surface, as a non-terrestrial base station. Similar to the 5G base station 111 and the 4G base station 121, the communication range or support area of ​​the communication satellite 131 is also called a cell and is illustrated as 132. In this way, the communication satellite 131, which is a non-terrestrial base station, provides the satellite communication cell 132, which is a non-terrestrial communication cell, to the ground. A terrestrial communication device 2 can perform satellite communication if it is located inside the satellite communication cell 132. Similar to the 5G base station 111 in the 5G wireless communication system 11 and the 4G base station 121 in the 4G wireless communication system 12, the communication satellite 131, which is a base station in the satellite communication system 13, can wirelessly communicate with the communication device 2 in the satellite communication cell 132 directly or indirectly via an aircraft or the like. The radio access technology that the communication satellite 131 uses for radio communication with the communication device 2 in the satellite communication cell 132 may be 5G NR, the same as the 5G base station 111, or LTE or LTE-Advanced, the same as the 4G base station 121, or any other radio access technology that can be used by the communication device 2. Therefore, the communication device 2 does not need to be provided with special functions or components for satellite communication.

[0024] The satellite communication system 13 includes a gateway 133 as a ground station installed on the ground and capable of communicating with a communication satellite 131. The gateway 133 includes a satellite antenna for communicating with the communication satellite 131, and is connected to a 5G base station 111 and a 4G base station 121 as terrestrial base stations constituting a terrestrial network (TN) via their respective wireless access technologies, such as 5G NR or LTE, or other wired or wireless access technologies or interfaces. In this way, the gateway 133 connects the non-terrestrial network (NTN) constituted by the communication satellite 131 as a non-terrestrial base station or satellite base station and the TN constituted by the terrestrial base stations 111 and 121 so that they can communicate with each other. When the communication satellite 131 performs 5G communication with the communication device 2 in the satellite communication cell 132 using 5G NR, the 5GC connected via the gateway 133 and the 5G base station 111 (or a 5G radio access network) in the TN is used as the core network, and when the communication satellite 131 performs 4G communication with the communication device 2 in the satellite communication cell 132 using LTE or LTE-Advanced, the EPC connected via the gateway 133 and the 4G base station 121 (or a 4G radio access network) in the TN is used as the core network. In this way, appropriate cooperation is achieved between different wireless communication systems such as 5G communication, 4G communication, and satellite communication via the gateway 133.

[0025] Satellite communication using a communication satellite 131 is primarily used to cover areas where terrestrial base stations such as 5G base station 111 and 4G base station 121 are not installed or are few in number. In the illustrated example, a communication device 2D located outside the communication cells of all terrestrial base stations communicates with the communication satellite 131. Meanwhile, communication devices 2A, 2B, and 2C that can communicate satisfactorily with any terrestrial base station are also within a satellite communication cell 132 and can therefore communicate with the communication satellite 131. However, by communicating with a terrestrial base station rather than the communication satellite 131 as a satellite base station, the limited communication resources (including power) of the communication satellite 131 are conserved for the communication device 2D and the like. The communication satellite 131 improves the quality of communication with the communication device 2D by directing communication radio waves toward the communication device 2D within the satellite communication cell 132 using beamforming.

[0026] The size of the satellite communication cell 132 of the communication satellite 131 serving as a satellite base station can be set arbitrarily depending on the number of beams emitted by the communication satellite 131; for example, a satellite communication cell 132 with a diameter of approximately 24 km can be formed by combining up to 2,800 beams. As shown in the figure, the satellite communication cell 132 is typically larger than a terrestrial communication cell such as the 5G cell 112 or the 4G cell 122, and may include one or more 5G cells 112 and / or 4G cells 122 therein. Note that, although the above example illustrates a communication satellite 131 flying in low orbit at an altitude of approximately 500 km to 700 km above the Earth's surface as a flying non-terrestrial base station, a communication satellite flying in high orbit such as a geostationary orbit, or an unmanned or manned aircraft or drone flying in the atmosphere at a lower altitude (for example, approximately 20 km above the Earth's surface) such as the stratosphere, may also be used as a non-terrestrial base station in addition to or instead of the communication satellite 131.

[0027] FIG. 2 is a functional block diagram illustrating a communication control device 3 according to this embodiment. The communication control device 3 includes a roaming restricted area setting unit 31, a roaming restriction relaxation unit 32, a restriction relaxation information providing unit 33, a connection control unit 34, a situation determination unit 35, and a communication quality determination unit 36. Some of these functional blocks may be omitted as long as the communication control device 3 can achieve at least some of the actions and / or effects described below. These functional blocks are realized by the cooperation of hardware resources, such as a central processing unit (CPU), memory, input devices, output devices, and peripheral devices connected to the computer, and software executed using these resources. Regardless of the type or location of the computer, each of the above functional blocks may be realized by the hardware resources of a single computer or by combining hardware resources distributed across multiple computers.

[0028] In particular, in this embodiment, some or all of the functional blocks of the communication control device 3 may be realized in a centralized or decentralized manner by computers and processors provided in the communication device 2, the RAN including the base stations 111, 121, and 131, the gateway 133, and the core network. As will be described later, this embodiment illustrates a PLMN1 (first network) that is a home network for a specific communication device 2 and a PLMN2 (second network) that is a roaming network for that communication device 2. The roaming restricted area setting unit 31, the roaming restriction relaxation unit 32, and the restriction relaxation information providing unit 33 are preferably provided on the PLMN2 side (e.g., the core network and / or RAN of PLMN2) (however, some or all of these may be provided on the PLMN1 side and / or the communication device 2), and the connection control unit 34, the situation determination unit 35, and the communication quality determination unit 36 ​​are preferably provided on the PLMN1 side (e.g., the core network and / or RAN of PLMN1) (however, some or all of these may be provided on the PLMN2 side and / or the communication device 2).

[0029] In this embodiment, a specific example is given of communication control or connection control of the illustrated communication device 2 by the communication control device 3. The communication device 2 is a UE whose home network is PLMN1, which is a first network. That is, a user or administrator of the communication device 2 (hereinafter collectively referred to as a user) has a contract for communication services with a first communication carrier, which is an MNO or MVNO that operates PLMN1. In principle, the communication device 2 communicates by being connected to a base station and / or a communication cell belonging to PLMN1, which is a home network.

[0030] The second network, PLMN2, is operated by a second carrier that is an MNO or MVNO different from the first carrier. Under an alliance or contract between the first carrier and the second carrier, a communication device 2 that has a contract with the first carrier may also be provided with communication services from the PLMN2 that is not under contract. Typically, the PLMN2, which is a roaming network, provides communication services to the communication device 2 as an alternative when there is no communication cell of the PLMN1, which is the home network, at the current location of the communication device 2 or when the communication quality provided by the PLMN1 is insufficient.

[0031] 2 representatively illustrates one communication cell (e.g., a terrestrial communication cell) or home cell HC belonging to PLMN1 as a home network, and one terrestrial communication cell TC and one non-terrestrial communication cell NTC belonging to PLMN2 as a roaming network. PLMN1 and / or PLMN2 may typically include a number of communication cells (not shown). As will be described later, the communication control device 3 appropriately switches the connection destination of the communication device 2 between the home cell HC, the terrestrial communication cell TC, and the non-terrestrial communication cell NTC depending on the situation.

[0032] The roaming restricted area setting unit 31 sets a roaming restricted area RA in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies in PLMN2 as a roaming network. The roaming restricted area RA may be an area including only one communication cell belonging to PLMN2, but is preferably an area including multiple communication cells (e.g., a terrestrial communication cell TC and a non-terrestrial communication cell NTC) belonging to PLMN2, as in the illustrated example.

[0033] More preferably, the roaming restriction area setting unit 31 sets the roaming restriction area RA in units of tracking areas or location registration areas in the PLMN 2 serving as a roaming network. A tracking area is set to track or detect the approximate location of the communication device 2. Each tracking area is typically made up of a large number of base stations and / or communication cells. For example, a certain MNO in Japan covers the entire country with several dozen location registration areas.

[0034] In this way, the roaming restricted area setting unit 31 sets a relatively large area such as a tracking area as a roaming restricted area RA, and thereby permits roaming connection of the communication device 2 in the roaming restricted area RA only in an emergency, in principle. Therefore, in normal times other than an emergency, roaming connection of the communication device 2 to a terrestrial communication cell TC, etc. is restricted or prohibited, in principle, on the assumption that communication services of sufficient quality are provided from the PLMN1 (e.g., home cell HC) as the home network. The roaming restricted area setting unit 31 may be interpreted as a functional unit that sets so-called disaster roaming for the roaming restricted area RA.

[0035] The roaming restriction relaxation unit 32 relaxes the restriction on roaming connections under normal circumstances for specific communication cells included in the roaming restricted area RA set by the roaming restricted area setting unit 31. For example, the roaming restriction relaxation unit 32 removes the prohibition on roaming connections under normal circumstances for specific communication cells included in the roaming restricted area RA. In the illustrated example, the roaming restriction relaxation unit 32 relaxes the restriction on roaming connections under normal circumstances for non-terrestrial communication cells NTC (for example, satellite communication cells 132 provided by communication satellites 131) included in the roaming restricted area RA as a tracking area.

[0036] In this way, the non-terrestrial communication cell NTC in which the restrictions on roaming connections during normal times are relaxed allows the communication device 2 to make a roaming connection during normal times as well as during emergencies. However, the roaming restriction relaxation unit 32 may impose certain restrictions or conditions on the roaming connection to the non-terrestrial communication cell NTC during normal times. Examples of such restrictions or conditions on the roaming connection during normal times include that there are sufficient communication resources available for roaming communication in the non-terrestrial communication cell NTC, that there is no home cell HC to which the communication device 2 can connect, that the communication quality of the home cell HC is insufficient, that roaming connections are permitted only during specific time periods, that roaming connections are permitted only in specific areas within the non-terrestrial communication cell NTC, etc.

[0037] Note that, when the roaming restricted area RA includes multiple non-terrestrial communication cells NTC, the roaming restriction relaxation unit 32 may relax the restriction on roaming connections during normal times for all of the non-terrestrial communication cells NTC, or may relax the restriction on roaming connections during normal times for some of the non-terrestrial communication cells NTC. As an example of the latter, the roaming restriction relaxation unit 32 may relax the restriction on roaming connections during normal times for a relatively wide satellite communication cell 132 provided by a communication satellite 131 flying in low-earth orbit (allowing roaming connections during normal times), while not relaxing the restriction on roaming connections during normal times for a relatively narrow non-terrestrial communication cell NTC provided by an unmanned or manned aircraft or drone flying in the atmosphere. Conversely, the roaming restriction relaxation unit 32 may relax the restriction on roaming connections during normal times for a relatively narrow non-terrestrial communication cell NTC provided by an aircraft or drone, while not relaxing the restriction on roaming connections during normal times for a relatively wide satellite communication cell 132 provided by the communication satellite 131.

[0038] Furthermore, when a roaming restricted area RA includes multiple terrestrial communication cells TC, the roaming restriction alleviation unit 32 may relax the restrictions on roaming connections during normal times for some or all of the terrestrial communication cells TC. For example, the roaming restriction alleviation unit 32 may relax the restrictions on roaming connections during normal times for relatively large macrocells and the like (allowing roaming connections during normal times), while not relaxing the restrictions on roaming connections during normal times for relatively small microcells, picocells, femtocells, and the like.

[0039] The roaming restriction alleviation unit 32 may relax restrictions on roaming connections during normal times for all or some of the communication cells that use a specific radio access technology (RAT) included in the roaming restricted area RA set by the roaming restricted area setting unit 31. For example, the roaming restriction alleviation unit 32 may relax restrictions on roaming connections during normal times (allow roaming connections during normal times) for all or some of the 4G cells 122 that use LTE or LTE-Advanced as the RAT, or for all or some of the satellite communication cells 132 that use a unique RAT conforming to LTE, LTE-Advanced, NR, 5G NR, etc., while not relaxing restrictions on roaming connections during normal times for all or some of the 5G cells 112 that use NR or 5G NR as the RAT.

[0040] The restriction relaxation information providing unit 33 provides restriction relaxation information that can identify a specific communication cell (in the illustrated example, a non-terrestrial communication cell NTC) for which the roaming restriction relaxation unit 32 has relaxed the restriction on roaming connections during normal times to the core network of PLMN1, which is the home network of the roaming connection source. For example, the restriction relaxation information providing unit 33, which is implemented in the core network of PLMN2, which is the roaming network, may provide, as the restriction relaxation information, identification information such as the ID of the non-terrestrial communication cell NTC for which the restriction on roaming connections during normal times has been relaxed, or may provide, as the restriction relaxation information, identification information such as the ID of the terrestrial communication cell TC for which the restriction on roaming connections during normal times has not been relaxed (i.e., for which only disaster roaming during an emergency is permitted). In the latter case, upon receiving the restriction relaxation information, PLMN1 can indirectly recognize that the non-terrestrial communication cell NTC that is not included in the list of communication cells for which only disaster roaming is permitted allows roaming connections during normal times.

[0041] It is preferable that the restriction relaxation information providing unit 33 provides restriction relaxation information in advance to the core network of PLMN1, which is the home network of the roaming connection source, during normal times when no abnormality such as a disaster has occurred. This restriction relaxation information is referenced by PLMN1 and / or the communication device 2 to realize exceptional roaming connections during normal times. Note that in an emergency, as a general rule, all communication cells included in the roaming restriction area RA allow roaming connections through disaster roaming, so the restriction relaxation information does not need to be referenced.

[0042] The connection control unit 34 is responsible for connection control of the communication device 2. In the illustrated example, the connection control unit 34 connects the communication device 2 to either a home cell HC belonging to PLMN1 as a home network, or a terrestrial communication cell TC or non-terrestrial communication cell NTC belonging to PLMN2 as a roaming network. When determining a connection destination for the communication device 2, the connection control unit 34 refers to at least any one of restriction relaxation information provided by the restriction relaxation information providing unit 33, situation information provided by a situation determination unit 35 described later, and communication quality information provided by a communication quality determination unit 36 ​​described later.

[0043] The situation determination unit 35 determines the current situation of the PLMN1 as a home network. For example, the situation determination unit 35 determines whether a disaster or emergency that requires disaster roaming has occurred in the PLMN1. The situation determination unit 35 may determine the current situation of the PLMN1 based on whether a public institution such as a national or local government has declared the occurrence of a disaster or emergency, or may determine the current situation of the PLMN1 based on whether an abnormality has actually occurred in the PLMN1 due to the disaster or emergency. For example, the situation determination unit 35 determines the situation as an "emergency" when the PLMN1 as a home network is in a state where it cannot provide communication services of sufficient quality to the communication device 2 due to a disaster or emergency, and determines the situation as a "normal" state when no disaster or emergency has occurred, or when the PLMN1 is in a state where it can provide communication services of sufficient quality to the communication device 2 even if a disaster or emergency has occurred.

[0044] The communication quality determination unit 36 ​​determines the quality of the communication service that the PLMN 1 serving as a home network provides to the communication device 2. In the illustrated example, the communication quality is determined between the home cell HC belonging to the PLMN 1 and the communication device 2. For example, the communication quality between the home cell HC and the communication device 2 may be determined comprehensively based on the strength of radio waves and the accuracy of reference signals from the communication device 2 measured at a base station (not shown) that provides the home cell HC, the strength of radio waves and the accuracy of reference signals from the base station (not shown) that provides the home cell HC measured at the communication device 2, and other various information that may affect the communication quality as understood by the base station (not shown) that provides the home cell HC and the communication device 2.

[0045] The communication quality determination unit 36 ​​may determine the quality of the communication service provided to the communication device 2 by the PLMN2 serving as a roaming network. In the illustrated example, the communication quality between the communication device 2 and a terrestrial communication cell TC belonging to the PLMN2, or the communication quality between the communication device 2 and a non-terrestrial communication cell NTC belonging to the PLMN2, may be determined. Note that, in determining the communication quality between the home cell HC, the terrestrial communication cell TC, and the non-terrestrial communication cell NTC, the communication device 2 does not need to be connected to each of these communication cells. In a typical example, for the communication device 2 connected to the PLMN1 serving as a home network, the communication quality between the communication device 2 and the connected home cell HC may be precisely determined, and the communication quality between the communication device 2 and the terrestrial communication cell TC and the non-terrestrial communication cell NTC serving as switching or roaming candidates may also be determined. In this case, the connection control unit 34 can appropriately determine whether to switch and which communication cell to switch to, based on a comparison of the communication quality in the connected home cell HC with the communication quality in multiple switching candidate communication cells (the terrestrial communication cell TC and the non-terrestrial communication cell NTC).

[0046] 3 is a flowchart showing an example of communication control by the communication control device 3. "S" in the flowchart denotes a step or process.

[0047] In S1, the roaming restricted area setting unit 31 sets a roaming restricted area RA in PLMN2 as a roaming network, in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies. In S2, the roaming restriction relaxation unit 32 relaxes the restrictions on roaming connections during normal times for specific communication cells (non-terrestrial communication cells NTC in the example of FIG. 2) included in the roaming restricted area RA set in S1. In S3, the restriction relaxation information providing unit 33 transmits restriction relaxation information, which can identify the specific communication cells for which the restrictions on roaming connections during normal times have been relaxed in S2, from the core network of PLMN2 as a roaming network during normal times. In S4, the core network of PLMN1 as a home network receives the restriction relaxation information transmitted in S3.

[0048] In S5, the core network of PLMN1 may notify or share some or all of the restriction relaxation information received in S4 with the communication device 2 connected to the PLMN1 (e.g., home cell HC). Having received the restriction relaxation information in this way, the communication device 2 can recognize in advance the communication cells in which roaming connection is permitted in PLMN2 as a roaming network. This effectively prevents the communication device 2 from making an unnecessary roaming connection request to a communication cell in which roaming connection is restricted or prohibited (e.g., a terrestrial communication cell TC under normal circumstances). Note that, instead of notifying the communication device 2 of the restriction relaxation information received in S4, the core network of PLMN1 may specifically specify the communication cell to which the communication device 2 should make a roaming connection request.

[0049] In S6, the situation determination unit 35 determines the current situation in the PLMN1 as the home network, i.e., whether it is normal or emergency. If the determination result in S7 is normal (Yes), the process proceeds to S8, where the core network of PLMN1 and / or the communication device 2 recognizes that roaming connections are permitted only to the specific communication cell (non-terrestrial communication cell NTC in the example of FIG. 2) for which roaming restrictions have been relaxed in S2, based on the restriction relaxation information received in S4.

[0050] In S10 following S8, the communication quality determination unit 36 ​​may determine the communication quality of a connectable communication cell. In the example of FIG. 2, the communication cells to which the communication device 2 can normally connect are the home cell HC and the non-terrestrial communication cell NTC (the terrestrial communication cell TC is normally unreachable due to the roaming restrictions set in S1). Therefore, in S10, the communication quality determination unit 36 ​​preferably determines the communication quality of each of the home cell HC and the non-terrestrial communication cell NTC. As a result, if it is determined that the communication quality of the home cell HC is sufficient for the communication device 2, in S11 the connection control unit 34 preferentially determines the home cell HC as the connection destination for the communication device 2. In a typical case, since the communication device 2 is already connected to the home cell HC, the connection state is maintained as is based on the determination made in S11.

[0051] On the other hand, if the result of S10 shows that the communication quality of the home cell HC is insufficient for the communication device 2 (for example, at the periphery (edge) of the home cell HC, communication quality is likely to deteriorate due to interference with other surrounding communication cells), and higher communication quality is achieved in the non-terrestrial communication cell NTC, in S11 the connection control unit 34 determines the non-terrestrial communication cell NTC as the (roaming) connection destination of the communication device 2. In a typical case, since the communication device 2 is connected to the home cell HC, a switching procedure such as handover or redirection from the home cell HC to the non-terrestrial communication cell NTC is initiated based on the determination in S11.

[0052] If the determination result in S7 is an emergency (No), the process proceeds to S9, where disaster roaming, etc. is activated. As a result, regardless of the restriction relaxation information for the specific communication cell (non-terrestrial communication cell NTC in the example of FIG. 2) received in S4, the core network of PLMN1 and / or communication device 2 recognizes that roaming connections to all communication cells (terrestrial communication cell TC and non-terrestrial communication cell NTC in the example of FIG. 2) included in the roaming restriction area RA set in S1 are permitted.

[0053] In S10 following S9, the communication quality determination unit 36 ​​may determine the communication quality of a connectable communication cell. In the example of FIG. 2, the communication cells to which the communication device 2 can connect in an emergency are the home cell HC, the terrestrial communication cell TC, and the non-terrestrial communication cell NTC. Therefore, in S10, the communication quality determination unit 36 ​​preferably determines the communication quality of each of the home cell HC, the terrestrial communication cell TC, and the non-terrestrial communication cell NTC. As a result, if it is determined that the communication quality of the home cell HC is sufficient for the communication device 2, in S11 the connection control unit 34 preferentially determines the home cell HC as the connection destination for the communication device 2. Typically, since the communication device 2 is already connected to the home cell HC, the connection state determined in S11 is maintained as is.

[0054] On the other hand, if the result of S10 shows that the communication quality of the home cell HC is insufficient for the communication device 2 (for example, if the entire PLMN 1 or the home cell HC is not functioning normally due to a disaster or emergency), and higher communication quality is achieved in the terrestrial communication cell TC and / or the non-terrestrial communication cell NTC, the connection control unit 34 determines in S11 that of the terrestrial communication cell TC or the non-terrestrial communication cell NTC, whichever has preferably higher communication quality, as the (roaming) connection destination of the communication device 2. In a typical case, since the communication device 2 is connected to the home cell HC, a switching procedure such as handover or redirection from the home cell HC to the terrestrial communication cell TC or the non-terrestrial communication cell NTC is initiated based on the determination in S11. Also, if the communication device 2 has been roaming to the non-terrestrial communication cell NTC during normal times, and higher communication quality is achieved in the terrestrial communication cell TC that has become newly available under the disaster roaming activated in S9, a switching procedure such as handover or redirection from the non-terrestrial communication cell NTC to the terrestrial communication cell TC may be initiated based on the determination in S11.

[0055] According to this embodiment, it is possible to relax the restrictions on roaming connections during normal times for specific communication cells (non-terrestrial communication cells NTC in the example of FIG. 2) included in the roaming restriction area RA in which roaming connections are restricted except in emergencies.

[0056] The present disclosure has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present disclosure.

[0057] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources include processors, ROMs, RAMs, and various integrated circuits. Examples of software resources include operating systems, applications, and other programs.

[0058] This disclosure may be expressed in the following terms:

[0059] Item 1: a roaming restricted area setting unit setting a roaming restricted area in which roaming connection is restricted in normal times and roaming connection is permitted in emergencies; a roaming restriction relaxation unit relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restriction area; A communication control device comprising at least one processor that executes the above. Item 2: Item 1. The communication control device according to item 1, wherein the roaming restricted area includes a plurality of communication cells. Item 3: the roaming restricted area includes a terrestrial communication cell provided on the ground by a terrestrial base station installed on the ground and a non-terrestrial communication cell provided on the ground by a flying non-terrestrial base station; the roaming restriction relaxation unit relaxes restrictions on roaming connections under normal circumstances for the non-terrestrial communication cells included in the roaming restriction area. Item 2. A communication control device. Item 4: 4. The communication control device according to item 3, wherein the non-terrestrial base station is a communication satellite flying in outer space. Item 5: 5. The communication control device according to any one of items 1 to 4, wherein the roaming restriction relaxation unit relaxes restrictions on roaming connections under normal circumstances for communication cells that use a specific wireless access technology included in the roaming restricted area. Item 6: 6. The communication control device according to any one of items 1 to 5, wherein the roaming restricted area setting unit sets the roaming restricted area in units of tracking areas. Item 7: The communication control device according to any one of items 1 to 6, wherein the at least one processor executes a restriction relaxation information providing unit to provide restriction relaxation information that can identify the specific communication cell in which the roaming restriction relaxation unit has relaxed the restrictions on roaming connections during normal times to the network from which the roaming connection originates. Item 8: 8. The communication control device according to item 7, wherein the restriction relaxation information providing unit provides the restriction relaxation information to a roaming connection source network during normal times. Item 9: the roaming restricted area setting unit sets the roaming restricted area in which roaming connection under normal circumstances is prohibited, the roaming restriction relaxation unit lifts the prohibition of roaming connection under normal circumstances for a specific communication cell included in the roaming restriction area. 9. A communication control device according to any one of items 1 to 8. Item 10: Setting a roaming restriction area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies; Relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area; A communication control method for performing the above. Item 11: Setting a roaming restriction area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies; Relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area; A storage medium that stores a communication control program that causes a computer to execute the above.

[0060] This application claims priority from Japanese Patent Application No. 2023-015961, filed on February 6, 2023, the entire contents of which are incorporated by reference. [Industrial Applicability]

[0061] The present disclosure relates to relaxing restrictions on roaming connections during normal times. [Explanation of symbols]

[0062] 1 wireless communication system, 2 communication device, 3 communication control device, 11 5G wireless communication system, 12 4G wireless communication system, 13 satellite communication system, 31 roaming restriction area setting unit, 32 roaming restriction relaxation unit, 33 restriction relaxation information providing unit, 34 connection control unit, 35 situation determination unit, 36 communication quality determination unit, 111 5G base station, 112 5G cell, 121 4G base station, 122 4G cell, 131 communication satellite, 132 satellite communication cell, 133 gateway.

Claims

1. a roaming restricted area setting unit setting a roaming restricted area in which roaming connection is restricted in normal times and roaming connection is permitted in emergencies; a roaming restriction relaxation unit relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restriction area; A communication control device that executes the above.

2. The communication control device according to claim 1 , wherein the roaming restricted area includes a plurality of communication cells.

3. the roaming restricted area includes a terrestrial communication cell provided on the ground by a terrestrial base station installed on the ground and a non-terrestrial communication cell provided on the ground by a flying non-terrestrial base station; the roaming restriction relaxation unit relaxes restrictions on roaming connections under normal circumstances for the non-terrestrial communication cells included in the roaming restriction area. The communication control device according to claim 2 .

4. The communication control device according to claim 3 , wherein the non-terrestrial base station is a communication satellite flying in outer space.

5. The communication control device according to claim 1 , wherein the roaming restriction relaxation unit relaxes restrictions on roaming connections under normal circumstances for communication cells that use a specific radio access technology and are included in the roaming restricted area.

6. The communication control device according to claim 1 , wherein the roaming restricted area setting unit sets the roaming restricted area in units of tracking areas.

7. 2. The communication control device according to claim 1, wherein a restriction relaxation information providing unit provides restriction relaxation information that can identify the specific communication cell in which the roaming restriction relaxation unit has relaxed the restriction on roaming connection during normal times to a network from which the roaming connection originates.

8. The communication control device according to claim 7 , wherein the restriction relaxation information providing unit provides the restriction relaxation information to a roaming source network under normal circumstances.

9. the roaming restricted area setting unit sets the roaming restricted area in which roaming connection under normal circumstances is prohibited, the roaming restriction relaxation unit lifts the prohibition of roaming connection under normal circumstances for a specific communication cell included in the roaming restriction area. The communication control device according to claim 1 .

10. Setting a roaming restriction area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies; Relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area; A communication control method for performing the above.

11. Setting a roaming restriction area in which roaming connections are restricted during normal times and roaming connections are permitted during emergencies; Relaxing restrictions on roaming connections during normal times for specific communication cells included in the roaming restricted area; A communication control program that causes a computer to execute the above.

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