Communication Control Method

Abstract

To provide a communication control apparatus and the like which consider interference and delay between TN and NTN.SOLUTION: A communication control apparatus controls a terrestrial network including a terrestrial base station installed on the ground and capable of communicating with a communication device in a terrestrial communication cell provided by the terrestrial base station on the ground by means of temporally-continuous TN data, and a non-terrestrial network including a flying communication satellite and capable of communicating with a communication device in a satellite communication cell provided by the communication satellite on the ground by means of temporally-continuous NTN data. The communication control apparatus includes: a signal strength reduction unit that reduces signal strength of at least portion of at least one of the TN data and the NTN data at least in an overlapping area of the terrestrial communication cell and the flying communication cell; a communication delay acquisition unit that acquires communication delay between the communication satellite and the satellite communication cell; and a synchronization unit that synchronizes the TN data with the NTN data based on the communication delay acquired by the communication delay acquisition unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a communication control technique in a communication system. [Background technology]

[0002] The number, types, and uses of wireless communication devices, such as smartphones and Internet of Things (IoT) 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 the sixth-generation mobile communication system, or "6G," as the next-generation wireless communication standard following 5G.

[0003] Mobile communication (hereinafter also referred to as mobile communication) networks for mobile or portable communication devices (hereinafter collectively referred to as communication devices), such as smartphones and mobile phones, have generally been constructed using communication cells (hereinafter also referred to as terrestrial communication cells) provided by base stations (hereinafter also referred to as terrestrial base stations) installed on the ground. However, in some areas, it is difficult to install a sufficient number of terrestrial base stations for various reasons, which has led to the problem of relatively low quality of mobile communication.

[0004] To address these regional disparities in mobile communication quality and the so-called "out-of-range" problem of mobile communication devices in some areas, non-terrestrial networks (NTNs) are being considered. In NTNs, communication satellites and unmanned aerial vehicles flying in the atmosphere, such as outer space and the stratosphere, serve as base stations (hereinafter referred to as "airborne base stations," and communication satellites in particular are also referred to as "satellite base stations"), providing communication cells on the ground (hereinafter referred to as "airborne communication cells," and communication cells provided by communication satellites in particular are also referred to as "satellite communication cells"). Devices within the airborne communication cells communicate with the airborne base stations directly or indirectly via other communication devices. Providing airborne communication cells in areas where terrestrial communication cells are insufficient can improve the quality of mobile communication in those areas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-278886 Summary of the Invention [Problem to be solved by the invention]

[0006] The terrestrial communication cells and aerial communication cells provided to the ground by terrestrial base stations and aerial base stations may overlap with each other. When such terrestrial communication cells and aerial communication cells use overlapping or adjacent frequency bands, if the terrestrial communication radio waves from the terrestrial base stations and the aerial communication radio waves from the aerial base stations interfere with each other in the overlapping area of ​​these communication cells, a communication device in the overlapping area may be unable to communicate with one or both of the terrestrial base stations and the aerial base stations. Furthermore, aerial base stations such as communication satellites and unmanned aircraft are located farther from communication devices than terrestrial base stations installed on the ground, and therefore experience significant communication delays or propagation delays. Thus, the present inventors recognized that in a communication system in which a terrestrial network (TN) and a non-terrestrial network coexist, it is necessary to consider the interference and delays between the TN and the NTN.

[0007] The present invention has been made in view of the above circumstances, and its object is to provide a communication control device and the like that takes into consideration interference and delay between TN and NTN. [Means for solving the problem]

[0008] In order to solve the above problem, a communication control device of one embodiment of the present invention is a communication control device that controls a ground network composed of a terrestrial base station installed on the ground and capable of communication with a communication device in a ground communication cell provided to the ground by the terrestrial base station using TN data that is continuous in time with the communication device, and a non-ground network composed of a flying air base station and capable of communication with a communication device in a flight communication cell provided to the ground by the flight base station using NTN data that is continuous in time with the communication device, and is equipped with a signal strength reduction unit that reduces the signal strength of at least a portion of the TN data and NTN data, at least in the overlapping area of ​​the ground communication cell and the flight communication cell, a communication delay acquisition unit that acquires the communication delay between the flight base station and the flight communication cell, and a synchronization unit that synchronizes the TN data and NTN data based on the communication delay acquired by the communication delay acquisition unit.

[0009] According to this aspect, the signal strength reducing unit reduces the signal strength of part of the TN or NTN data, thereby reducing interference between TN communication radio waves and NTN communication radio waves in an overlapping area between a ground communication cell and an airborne communication cell. Also, the synchronization unit synchronizes the TN data and NTN data based on the communication delay between the airborne base station and the airborne communication cell, thereby enabling the signal strength reducing unit to accurately reduce interference between TN communication radio waves and NTN communication radio waves at the desired timing.

[0010] Another aspect of the present invention is a communication control method for controlling a ground network configured by a ground base station installed on the ground and capable of communicating with a communication device in a ground communication cell provided to the ground by the ground base station using TN data that is continuous in time with the communication device, and a non-ground network configured by a flying air base station and capable of communicating with a communication device in an air communication cell provided to the ground by the air base station using NTN data that is continuous in time with the communication device, the method comprising: a signal strength reducing step of reducing signal strength of at least part of the TN data and the NTN data at least in an overlapping area between the ground communication cell and the air communication cell; a communication delay acquiring step of acquiring a communication delay between the air base station and the air communication cell; and a synchronization step of synchronizing the TN data and the NTN data based on the communication delay acquired in the communication delay acquiring step.

[0011] Any combination of the above components, and any transformation of the present invention into a method, device, system, recording medium, computer program, etc., are also valid aspects of the present invention. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a communication control device and the like that takes into consideration interference and delay between a TN and an NTN. [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] A wireless communication system is shown diagrammatically, focusing on a communication satellite. [Figure 3] FIG. 2 is a functional block diagram illustrating the concept of a communication control device. [Figure 4] TN frame and NTN frame are shown schematically. [Figure 5] An example is shown in which a 5G base station on the TN side transmits ABS-related information to another 5G base station on the NTN side. [Figure 6] An example of ABS-related information shared between the TN and NTN sides is shown below. [Figure 7] This shows an NTN frame transmitted from the gateway earlier in time, and a TN frame transmitted from the 5G base station later in time. [Figure 8] 1 shows a first embodiment of a communication control device. [Figure 9] 1 shows a first embodiment of a communication control device. [Figure 10] 2 shows a second embodiment of the communication control device. [Figure 11] 2 shows a second embodiment of the communication control device. [Figure 12] 10 shows a third embodiment of the communication control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 schematically illustrates an overview of a wireless communication system 1 to which a communication control device according to an embodiment of the present invention is applied. The wireless communication system 1 includes a 5G wireless communication system 11 conforming 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), a 4G wireless communication system 12 conforming 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, and a satellite communication system 13 that handles satellite communication via a communication satellite 131. Although not illustrated, 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 (e.g., 6G), or any wireless communication system that is not associated with a generation, such as Wi-Fi (registered trademark).

[0015] The 5G wireless communication system 11 includes communication devices 2A, 2B, 2C, and 2D (hereinafter sometimes 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 sometimes 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 range 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 sometimes collectively referred to as 5G cells 112 or cells 112).

[0016] 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 several hundred meters are called macrocells. 5G often uses high-frequency radio waves such as millimeter waves, and because of their high line-of-sight characteristics, the radio waves are blocked by obstacles, shortening the communication distance. For this reason, 5G tends to use smaller cells than 4G and earlier generations.

[0017] 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.

[0018] The 4G wireless communication system 12 includes multiple 4G base stations 121 (only one of which is shown in FIG. 1 ) that are installed on the ground and 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 coverage area or support area of ​​each 4G base station 121 is also called a cell, and is illustrated as 122.

[0019] 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.

[0020] 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 the EPC core network, and communication with communicator 2B is performed. Furthermore, communicator 2D is not capable of communication with any of the 5G base stations 111 and 4G base station 121, and therefore performs communication via satellite communication system 13, which will be described next.

[0021] The satellite communication system 13 is a wireless communication system that uses a communication satellite 131 as a flight base station, which is a low-orbit satellite that flies in space in a low orbit at an altitude of approximately 500 km to 700 km above the Earth's surface. 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 as a flight base station provides the satellite communication cell 132 as a flight communication cell to the ground. A communication device 2 on the ground can perform satellite communication if it is located within 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 as 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. For this reason, the communication device 2 does not need to be provided with special functions or components for satellite communication.

[0022] 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 that constitute a terrestrial network (TN). In this way, the gateway 133 connects the NTN formed by the communication satellite 131 to the TN formed 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 a communication device 2 in a 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. When the communication satellite 131 performs 4G communication with a 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.

[0023] 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.

[0024] 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 base station, a communication satellite flying in high orbit such as a geostationary orbit, or an unmanned or manned aircraft 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 flying base station in addition to or instead of the communication satellite 131.

[0025] As described above, the wireless communication system 1 according to this embodiment includes ground networks (TN) 11, 12 capable of communicating with communication devices 2 in ground communication cells 112, 122 provided on the ground by ground base stations 111, 121 installed on the ground, and a non-ground network (NTN) 13 capable of communicating with communication devices 2 in flight communication cell 132 provided on the ground by a flying flight base station 131. The communication control device according to this embodiment controls the TN and NTN.

[0026] FIG. 2 shows a schematic diagram of a wireless communication system 1 similar to that shown in FIG. 1, with a communication satellite 131 at the center. As described above, the communication satellite 131 can combine up to 2,800 beams to form one or more satellite communication cells 132 on the ground. A communication device 2 (2C, 2D, etc.) within the satellite communication cell 132 performs 5G communication and / or 4G communication with a communication device 2 (2B, 2C, etc.) within a TN (shown and / or not shown) via the communication satellite 131 and a gateway 133, and / or communicates with any other communication device via a 5G communication network (5GC) and / or an EPC (Electrical Power Control) serving as a core network. The gateway 133, which connects the NTN and the TN so that they can communicate with each other, is installed on the ground and is configured to be able to communicate with both the communication satellite 131 as an airborne base station and the 5G base station 111 and / or 4G base station 121 (not shown) as a terrestrial base station.

[0027] 2 may indicate that the gateway 133 is directly connected to the 5G base station 111, or may indicate that the gateway 133 is indirectly connected to a 5G base station 111 included in another radio access network (RAN) via a CN. In other words, the gateway 133 is configured to be able to communicate with any 5G base station 111 (and / or 4G base station 121) in the 5G wireless communication system 11 (and / or 4G wireless communication system 12) directly without via a CN or indirectly via a CN.

[0028] In the example of Figure 2, only one satellite communication cell 132 of one or more satellite communication cells 132 formed on the ground by a communication satellite 131 is shown, and one 5G cell 112 included therein is formed by one 5G base station 111. In this example, the entire 5G cell 112 is an overlapping area between the 5G cell 112 as a terrestrial communication cell and the satellite communication cell 132 as an airborne communication cell. In this overlapping area, TN communication radio waves from the 5G base station 111 (shown as "Terrestrial gNB" or "TN gNB" in Figure 2) and NTN communication radio waves from the communication satellite 131 (shown as "Satellite gNB" or "NTN gNB" in Figure 2) coexist.

[0029] In a central area A1 of the 5G cell 112 serving as an overlapping area and close to the 5G base station 111, the signal strength of the TN communication radio waves from the 5G base station 111 is significantly greater than the signal strength of the NTN communication radio waves from the communication satellite 131, so that a communication device 2B in the central area A1 can perform stable 5G communication with the 5G base station 111. On the other hand, in a peripheral area A2 of the 5G cell 112 serving as an overlapping area and far from the 5G base station 111, there is no significant difference in the signal strength of the TN communication radio waves from the 5G base station 111 and the NTN communication radio waves from the communication satellite 131, so that the TN communication radio waves and the NTN communication radio waves interfere with each other. The interference is particularly severe when the TN communication radio waves and the NTN communication radio waves use overlapping or adjacent frequency bands, so that a communication device 2C in the peripheral area A2 cannot perform stable 5G communication with either the 5G base station 111 or the communication satellite 131. In addition, in the non-overlapping area A3 of the satellite communication cell 132 that does not overlap with the 5G cell 112, the signal strength of the NTN communication radio waves from the communication satellite 131 is significantly greater than the signal strength of the TN communication radio waves from the 5G base station 111, so the communication device 2D within the non-overlapping area A3 can perform stable 5G communication with the communication satellite 131.

[0030] As described above, in a wireless communication system 1 in which TN and NTN coexist, measures must be taken to ensure stable communication between the communication device 2C in the peripheral area A2 or interference area A2 where the two networks interfere. Figure 3 is a functional block diagram illustrating the concept of a communication control device 3 that achieves stable communication in the interference area A2. The communication control device 3 includes a signal strength reducing unit 31, an orbit information acquiring unit 32, a communication delay acquiring unit 33, and a synchronization unit 34. These functional blocks are implemented by the cooperation of hardware resources, such as a computer's central processing unit, 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 implemented by the hardware resources of a single computer or by a combination of hardware resources distributed across multiple computers. In particular, in this embodiment, some or all of the functional blocks of the communication control device 3 may be implemented by computers or processors provided in the communication device 2 (e.g., 2C), communication satellite 131, gateway 133, or terrestrial base stations 111 and 121 directly or indirectly connected to the gateway 133.

[0031] The signal strength reduction unit 31 reduces the signal strength of at least a portion of the TN data transmitted by the terrestrial base station 111 constituting the TN and the NTN data transmitted by the gateway 133 and / or communication satellite 131 constituting the NTN, at least in the overlapping region or interference region A2 of the terrestrial communication cell 112 and the satellite communication cell 132. Figure 4 schematically shows a TN frame generated and transmitted by the 5G base station 111, and an NTN frame generated by the terrestrial base stations 111 and 121 connected to the gateway 133 and transmitted by the gateway 133. A TN frame (shown as "TN gNB Frame" in Figure 4) is composed of temporally consecutive TN data or TN subframes, and an NTN frame (shown as "NTN GW Frame" in Figure 4) is composed of temporally consecutive NTN data or NTN subframes.

[0032] In 5G, each 10 ms frame is composed of ten 1 ms subframes, each subframe is composed of one or more variable length (1 ms, 0.5 ms, 0.25 ms, etc.) slots, and each slot is composed of 14 variable length OFDM symbols. In this embodiment, an example is described in which TN data or NTN data as a processing unit of the signal strength reducing unit 31 corresponds to a 1 ms subframe, but the signal strength reducing unit 31 may process the TN data or NTN data in units of frames (10 ms), slots, symbols, etc. Furthermore, if a signal configuration different from that of 5G is adopted in a wireless communication standard other than 5G (such as 6G), the signal strength reducing unit 31 may process the TN data or NTN data in any signal unit in the time domain of the signal configuration.

[0033] 4, the signal strength reducing unit 31 reduces the signal strength of some of the 10 TN subframes included in the TN frame. Specifically, the signal strength reducing unit 31 reduces the signal strength of the third TN subframe TN-3 of each TN frame, the sixth TN subframe TN-6 of each TN frame, and the ninth TN subframe TN-9 of each TN frame. In this way, the signal strength reducing unit 31 reduces the signal strength of the TN data according to a predetermined pattern that specifies some (third, sixth, and ninth) subframes included in the TN frame as a TN data group.

[0034] The signal strength reducing unit 31 may reduce the signal strength of the TN subframes TN-3, 6, and 9 to be processed to zero, in which case transmission of TN signals or TN data in the TN subframes TN-3, 6, and 9 to be processed is prohibited. Specifically, in 5G, in the TN subframes TN-3, 6, and 9 to be processed by the signal strength reducing unit 31, data transmission is not performed not only on the PDSCH (Physical Downlink Shared Channel) that transmits actual data but also on the PDCCH (Physical Downlink Control Channel) that transmits control data for the actual data. Note that, even in the TN subframes TN-3, 6, and 9 to be processed by the signal strength reducing unit 31, it is preferable to transmit minimum control data related to communication control in the TN, such as CSI-RS (Channel State Information Reference Signal) and SSB (Synchronization Signal Block), as usual. As described above with reference to FIG. 2, the TN frames transmitted from the 5G base station 111 are used for communication with the communication device 2B in the central area A1. In the example of Figure 4, the TN subframes TN-3, 6, and 9 that are processed by the signal strength reduction unit 31 do not contain actual data, so the communication device 2B communicates with the 5G base station 111 using the seven TN subframes that are not processed by the signal strength reduction unit 31.

[0035] The above-described processing by the signal strength reducing unit 31 is sometimes called ABS (Almost Blank Subframe). In the following embodiments, an example will be described in which the signal strength reducing unit 31 performs ABS processing on a TN frame, but the signal strength reducing unit 31 may also perform ABS processing on an NTN frame, or may reduce the signal strength of some of the 10 NTN subframes included in the NTN frame.

[0036] In the NTN frame that is not subject to ABS processing, all 10 NTN subframes are available for communication of actual data (NTN data). As described above with reference to Figure 2, the NTN frame transmitted from the gateway 133 and / or communication satellite 131 is used for communication with the communication device 2D in the non-overlapping area A3. In the example of Figure 4, the NTN frame is also used for communication with the communication device 2C in the interference area A2. Specifically, of the 10 NTN subframes, three NTN subframes NTN-3, 6, 9 (shown as "TN ABS Subframes" in Figure 4) that are the same timing as the three TN subframes TN-3, 6, 9 that are subject to ABS processing by the signal strength reduction unit 31 are used for communication with the communication device 2C in the interference area A2, and seven NTN subframes (shown as "NTN Data" in Figure 4) that are the same timing as the seven TN subframes (shown as "TN Data" in Figure 4) that are not subject to ABS processing by the signal strength reduction unit 31 are used for communication with the communication device 2D in the non-overlapping area A3.

[0037] In the interference area A2, the TN communication radio waves from the 5G base station 111 and the NTN communication radio waves from the communication satellite 131 interfere with each other, but since the TN communication radio waves from the 5G base station 111 are weakened by the signal strength reduction unit 31 during the ABS processing period, the communication device 2C within the interference area A2 can normally receive the NTN communication radio waves from the communication satellite 131. In this way, the gateway 133 and / or the communication satellite 131 communicate with the communication device 2C within the interference area A2 of the terrestrial communication cell 112 and the satellite communication cell 132 using the NTN data while the signal strength reduction unit 31 is reducing the signal strength of the TN data. On the other hand, in the non-overlapping area A3, the signal strength of the NTN communication radio waves from the communication satellite 131 is significantly greater than the signal strength of the TN communication radio waves from the 5G base station 111, so the communication device 2D within the non-overlapping area A3 can normally receive the NTN communication radio waves from the communication satellite 131 even outside the ABS processing period. In this way, of the 10 NTN subframes, NTN subframes NTN-3, 6, and 9 during the ABS processing period are preferentially allocated to communication device 2C in the interference area A2, and the remaining NTN subframes are allocated to communication device 2D in the non-overlapping area A3.

[0038] The ABS processing in FIG. 4 is executed according to orbital information of the communication satellite 131 acquired by the orbital information acquisition unit 32, which will be described later. For example, based on the orbital information of the communication satellite 131 acquired by the orbital information acquisition unit 32, as shown in FIG. 3, the communication control device 3 recognizes that an overlapping area (A1+A2) exists between the satellite communication cell 132 provided to the ground by the communication satellite 131 and the terrestrial communication cell 112 provided to the ground by the terrestrial base station 111, and that there is an interference area A2 where interference between the NTN communication radio waves and the TN communication radio waves is particularly severe, and starts ABS processing by the signal strength reduction unit 31. The signal strength reduction unit 31 provided on the TN side notifies the NTN side that ABS processing will be started via the terrestrial communication path "Xn" between the terrestrial base station 111 and the gateway 133 (i.e., between the TN and NTN) described with reference to FIG. 2. The orbital information of the communication satellite 131 acquired by the orbital information acquisition unit 32 is also shared with the 5G base station 111 (signal strength reduction unit 31), which executes the ABS processing. Upon receiving the command to start ABS processing, the signal strength reduction unit 31 shares a predetermined ABS pattern (designating the 3rd, 6th, and 9th subframes TN-3, 6, and 9 of the TN frame as ABS) as shown in FIG. 4 with the gateway 133 and / or other terrestrial base stations 111, 121 connected to the gateway 133 via the terrestrial communication path "Xn."

[0039] FIG. 5 shows an example in which the 5G base station 111 "NG-RAN node2" on the TN side, where the signal strength reduction unit 31 is installed, transmits ABS-related information (ABS IE) in a "RESOURCE STATUS UPDATE" to another 5G base station 111' "NG-RAN node1" on the NTN side connected to the gateway 133 via the terrestrial communication path "Xn." FIG. 6 shows an example of ABS-related information shared between the TN side and the NTN side via the terrestrial communication path "Xn." "ABS Pattern Info" indicates an ABS pattern. In the illustrated example, "ABS Pattern Info" is 40-bit data, with each bit corresponding to 40 temporally consecutive TN subframes. In the example of FIG. 4, where one TN frame is made up of 10 TN subframes, each of the 40 TN subframes included in four temporally consecutive TN frames can be individually designated as an ABS (TN subframes whose signal strength is reduced by the signal strength reduction unit 31). Specifically, a TN subframe with a bit of "1" is an ABS, and a TN subframe with a bit of "0" is a non-ABS (a TN subframe in which normal TN data is transmitted). "ABS Inactive" indicates that ABS processing is not being performed. For example, before the signal strength reduction unit 31 starts ABS processing, "ABS Inactive" is enabled, and after the signal strength reduction unit 31 starts ABS processing, "ABS Inactive" is disabled.

[0040] 4, the TN frame transmitted by the 5G base station 111 and the NTN frame transmitted by the gateway 133 and / or the communication satellite 131 must be synchronized with each other. Here, the NTN frame generated by the gateway 133 is transmitted to the communication devices 2C and 2D in the satellite communication cell 132 via the communication satellite 131, and therefore involves a large communication delay, transmission delay, propagation delay, etc. Therefore, in the communication control device 3 according to this embodiment, the orbit information acquisition unit 32, communication delay acquisition unit 33, synchronization unit 34, etc. described below recognize the communication delay of the NTN frame and synchronize the TN frame and the NTN frame.

[0041] The orbit information acquisition unit 32 acquires orbit information or position information of the communication satellite 131 as a flight base station. The communication delay acquisition unit 33 acquires or calculates the communication delay of the NTN frame between the gateway 133 and the satellite communication cell 132 via the communication satellite 131, based on the orbit information of the communication satellite 131 acquired by the orbit information acquisition unit 32, position information of the gateway 133 that is the source of the NTN frame, position information of the satellite communication cell 132 that is the destination of the NTN frame, and / or position information of the communication device 2 within the satellite communication cell 132. Here, the communication satellites 131 and gateways 133 that make up the NTN are broadly classified into a transparent type and a regenerative type, respectively.

[0042] The retransmission-type gateway 133 only has a relay function of retransmitting signals received from the RAN or CN to the communication satellite 131, and the retransmission-type communication satellite 131 only has a relay function of retransmitting signals received from the gateway 133 to the satellite communication cell 132 (the same applies to the reverse communication path). For this reason, the retransmission-type communication satellite 131 and the gateway 133 are not suitable for providing information processing functions such as the orbit information acquisition unit 32 and the communication delay acquisition unit 33. Therefore, when providing an information processing function on the transmitting side of the NTN frame, it is preferable to provide the orbit information acquisition unit 32 and the communication delay acquisition unit 33 in the terrestrial base stations 111 and 121 connected to the gateway 133. Furthermore, when providing an information processing function on the receiving side of the NTN frame, it is preferable to provide the orbit information acquisition unit 32 and the communication delay acquisition unit 33 in the communication devices 2C and 2D in the satellite communication cell 132.

[0043] On the other hand, the regenerative communication satellite 131 and gateway 133 can be provided with information processing functions, and therefore may be provided with an orbit information acquisition unit 32 and a communication delay acquisition unit 33. When the communication satellite 131 is regenerative, the NTN frame communicated in downlink to the satellite communication cell 132 is essentially generated by the communication satellite 131, and therefore the only NTN communication delay that needs to be taken into account in synchronizing the TN frame and the NTN frame is the communication delay between the communication satellite 131 and the satellite communication cell 132 (the communication delay between the gateway 133 and the communication satellite 131 does not need to be taken into account). In this case, the communication delay acquisition unit 33 acquires the communication delay between the communication satellite 131 and the satellite communication cell 132.

[0044] The synchronization unit 34 synchronizes the TN frame or TN data transmitted by the 5G base station 111 and the NTN frame or NTN data transmitted by the gateway 133 and / or the communication satellite 131, based on the communication delay of the NTN acquired by the communication delay acquisition unit 33. A specific example will be described later, but when the synchronization unit 34 is provided on the NTN side (the communication satellite 131, the gateway 133, the terrestrial base stations 111 and 121 connected to the gateway 133, etc.), the synchronization unit 34 causes the gateway 133 and / or the communication satellite 131 to transmit the NTN frame earlier than the TN frame transmitted by the 5G base station 111 by the communication delay calculated by the communication delay acquisition unit 33. Furthermore, when the synchronization unit 34 is provided on the TN side (the terrestrial base stations 111 and 121, the communication device 2, etc.), the synchronization unit 34 delays the start of transmission of the TN frame by the communication delay acquired by the communication delay acquisition unit 33 after the gateway 133 and / or the communication satellite 131 starts transmitting the NTN frame. As shown schematically in Figure 7, in either case, a round trip time (RTT) delay TA corresponding to the communication delay acquired by the communication delay acquisition unit 33 is set between the NTN frame "NTN GW Frame" transmitted earlier from the gateway 133 and the TN frame "TN gNB Frame" transmitted later from the 5G base station 111.

[0045] As described above, the functional blocks 31 to 34 of the communication control device 3 can be realized in a distributed manner on the NTN side (communication satellite 131, gateway 133, terrestrial base stations 111 and 121 connected to the gateway 133, etc.) and the TN side (terrestrial base stations 111 and 121, communication device 2, etc.). In such a case, necessary information is shared in a timely manner among the functional blocks 31 to 34 through the terrestrial communication path "Xn" between the gateway 133 and terrestrial base stations 111 and 121 (i.e., between the NTN and TN) described with reference to FIG. 2, thereby realizing cooperative operation of the various units of the communication control device 3. Note that the orbit information acquisition unit 32 and the communication delay acquisition unit 33 are responsible for highly related processes, and therefore are preferably provided together on either the NTN side or the TN side.

[0046] Next, several examples of communication control by the communication control device 3 will be specifically shown.

[0047] In a first example of the communication control device 3 shown in FIGS. 8 and 9, a communication device 2C in the interference area A2 is equipped with a positioning sensor based on a satellite positioning system such as GPS or GNSS, which can measure its own position information. In this case, the orbital information acquisition unit 32 and the communication delay acquisition unit 33 are implemented in the communication device 2C. The communication device 2C functioning as the communication delay acquisition unit 33 calculates the communication delay between itself (the communication device 2C) and the communication satellite 131 based on its own position information measured by its own positioning sensor and the orbital information of the communication satellite 131 acquired by the orbital information acquisition unit 32. Note that the communication device 2C may acquire positional information of the gateway 133 via the terrestrial communication path "Xn" and the 5G base station 111, and may calculate the communication delay between the gateway 133 and the communication satellite 131 based on the orbital information of the communication satellite 131 acquired by the orbital information acquisition unit 32. The communication delay between the gateway 133 and the communication satellite 131 may be calculated by the 5G base station 111, the communication satellite 131, the gateway 133, the terrestrial base stations 111, 121 connected to the gateway 133, etc.

[0048] As shown in FIG. 8, the communication device 2C (UE) functioning as the communication delay acquisition unit 33 exchanges messages (Msg 1-4) according to a known RACH process or RACH procedure with the NTN-side terrestrial base station (gNB) connected to the gateway 133, thereby acquiring the accurate communication delay between the gateway 133 and the communication device 2C via the communication satellite 131. In this figure, the communication delay is represented as "TA" (Timing Advance). In a first step, when the communication device 2C transmits a first message (Msg 1), the communication device 2C estimates the communication delay (TA) based on its own position information measured by its own positioning sensor and the orbit information of the communication satellite 131 acquired by the orbit information acquisition unit 32, and applies the estimated communication delay (TA) to the first message (Msg 1). In a second step, the communication device 2C receives a second message (Msg 2) from the terrestrial base station (gNB) and applies a correction to the communication delay (TA) based on the second message (Msg 2). In the third step, the communication device 2C schedules the third message “Msg 3.” In the fourth step, the communication delay “TA” specific to the communication device 2C is obtained on the NTN side where the terrestrial base station “gNB” is installed.

[0049] 9 is a schematic diagram illustrating the synchronization process of the synchronization unit 34 based on the NTN communication delay TA acquired by the communication delay acquisition unit 33 through the RACH process of FIG. 8. The synchronization unit 34 causes the gateway 133 to transmit an NTN frame "NTN GW Frame" that is earlier than the TN frame "TN gNB Frame" transmitted by the 5G base station 111 by the communication delay TA acquired by the communication delay acquisition unit 33. As a result, the TN frame and the NTN frame received by the communication device 2C within the interference area A2 are synchronized with each other. Therefore, as described above with reference to FIG. 4, while the communication device 2C is receiving an NTN subframe (such as NTN-3) in the ABS processing target period assigned to the communication device 2C, the corresponding TN subframe (such as TN-3) is an ABS, and therefore the communication device 2C can successfully receive the NTN subframe assigned to itself.

[0050] 10 and 11 is suitable for a case where the communication device 2 in the satellite communication cell 132 does not have a positioning sensor. In the first embodiment in which the communication device 2 has a positioning sensor, all or part of the orbit information acquisition unit 32 and the communication delay acquisition unit 33 are realized in the communication device 2. However, in the second embodiment in which the communication device 2 does not have a positioning sensor, all or part of the orbit information acquisition unit 32 and the communication delay acquisition unit 33 are realized on the NTN side, specifically, in the terrestrial base stations 111 and 121 connected to the gateway 133. Furthermore, in the first embodiment in which the communication device 2 has a positioning sensor, the position information of the communication device 2 is used when calculating the communication delay of the NTN. However, in the second embodiment in which the communication device 2 does not have a positioning sensor, the communication delay of the NTN is calculated using representative position information of the satellite communication cell 132 acquired by the satellite communication cell position acquisition unit 35 as a flight communication cell position acquisition unit. The representative position information of the satellite communication cell 132 is typically position information of the center O of the satellite communication cell 132, as shown in Fig. 10. The satellite communication cell position acquisition unit 35 can calculate the representative position information of the satellite communication cell 132 based on the orbit information of the communication satellite 131 acquired by the orbit information acquisition unit 32 (not shown), terrestrial topography information, or elevation difference information.

[0051] The communication delay acquisition unit 33 (not shown) provided on the NTN side can calculate the communication delay between the communication satellite 131 and the satellite communication cell 132 based on the representative position information of the satellite communication cell 132 acquired by the satellite communication cell position acquisition unit 35 and the orbit information of the communication satellite 131 acquired by the orbit information acquisition unit 32. This communication delay covers the distance d0 between the communication satellite 131 and the center O of the satellite communication cell 132 in FIG. 10. Furthermore, the communication delay acquisition unit 33 provided on the NTN side can calculate the communication delay between the gateway 133 and the communication satellite 131 based on the known position information of the gateway 133 and the orbit information of the communication satellite 131 acquired by the orbit information acquisition unit 32. This communication delay covers the distance d1 between the gateway 133 and the communication satellite 131 in FIG. 10. In this way, the communication delay acquisition unit 33 provided on the NTN side can calculate the communication delay of the NTN over the total distance d0 + d1 between (the center O of) the satellite communication cell 132 and the gateway 133. As described above, when the communication satellite 131 is a regenerative type, the communication delay acquisition unit 33 only needs to acquire the communication delay of NTN over the distance d0 between the satellite communication cell 132 (center O) and the communication satellite 131.

[0052] 11 is a diagram showing a synchronization process of the synchronization unit 34 based on the communication delay TA of the NTN acquired by the communication delay acquisition unit 33 through the process of FIG. 10. After the gateway 133 starts transmitting the NTN frame "NTN GW Frame" corresponding to the ABS process, the synchronization unit 34 delays the start of transmission of the TN frame "TN gNB Frame" corresponding to the ABS process by the communication delay TA "RTT Delay" acquired by the communication delay acquisition unit 33. For example, the synchronization unit 34 sets the transmission start time of the first TN subframe TN-3 of the ABS process target period as "T TN gNB ", then the transmission start time of the first NTN subframe NTN-3 in the ABS processing period is "T TN gNB-RTT Delay". As a result, the TN frame and the NTN frame received by the communication device 2C in the interference area A2 are synchronized with each other, and ABS processing starts simultaneously for the TN frame and the NTN frame. Therefore, it is possible to effectively prevent the communication device 2C in the interference area A2 from receiving an NTN frame after the start of ABS processing while receiving a TN frame before the start of ABS processing, or from receiving a TN frame after the start of ABS processing while receiving an NTN frame before the start of ABS processing.

[0053] The third embodiment of the communication control device 3 shown in FIG. 12 is also suitable for a case where the communication device 2 in the satellite communication cell 132 does not include a positioning sensor. FIG. 12 schematically illustrates synchronization processing by the synchronization unit 34 based on the NTN communication delay TA acquired by the communication delay acquisition unit 33 through processing similar to that of FIG. 10. The synchronization unit 34 causes the gateway 133 to transmit an NTN frame "NTN GW Frame" that is earlier than the TN frame "TN gNB Frame" transmitted by the 5G base station 111 by the communication delay TA acquired by the communication delay acquisition unit 33. As a result, the TN frame and the NTN frame received by the communication device 2C in the interference area A2 are synchronized with each other. Therefore, as described above with reference to FIG. 4, while the communication device 2C is receiving an NTN subframe (e.g., NTN-3) during the ABS processing period assigned to the communication device 2C, the corresponding TN subframe (e.g., TN-3) is an ABS, and therefore the communication device 2C can successfully receive the NTN subframe assigned to itself.

[0054] In general, a communication device 2 constantly measures the signal strength and the like of a serving cell, which is a communication cell in communication, and of adjacent cells adjacent to the serving cell. The communication device 2 also constantly measures channel state information (CSI) of the channel in communication. When such a communication device 2 is located within the interference area A2 shown in Fig. 3, it is necessary to take into consideration the ABS pattern shown in Fig. 4 when measuring the satellite communication cell 132 as a serving cell or an adjacent cell, or measuring the CSI.

[0055] 3 performs measurements for radio link monitoring (RLM) and radio resource management (RRM) of the satellite communication cell 132 as a serving cell during an ABS processing target period (the third, sixth, and ninth subframe periods in the example of FIG. 4) when there is no interference from the 5G cell 112. If the communication device 2C were to measure the satellite communication cell 132 as a serving cell outside the ABS processing target period, interference from the 5G cell 112 would cause radio link failure (RLF).

[0056] Similarly, the communication device 2C in Fig. 3 performs measurements for RRM of the satellite communication cell 132, which is an adjacent cell, during an ABS processing target period when there is no interference from the 5G cell 112. In this case, the communication device 2C is not in communication with the satellite communication cell 132, but acquires an ABS pattern such as that shown in Fig. 4 or 6 via a 5G base station 111 or the like of the 5G cell 112, which is the serving cell, and then measures the satellite communication cell 132, which is an adjacent cell. For example, the NTN base stations 111 and 121 connected to the gateway 133 transmit parameters and configuration information of an SMTC (SSB based Measurement Timing Configuration) window based on the ABS pattern of the satellite communication cell 132 to the communication device 2C via the terrestrial communication path "Xn" or the like, thereby enabling the communication device 2C to accurately measure the NTN subframe of the satellite communication cell 132 during the ABS processing target period.

[0057] When the communication device 2C in the interference area A2 measures the CSI, it is preferable to separately measure a first CSI over the ABS processing period when there is no interference from the satellite communication cell 132 and the 5G cell 112, and a second CSI over the period outside the ABS processing period when there is interference from the satellite communication cell 132 and the 5G cell 112. This is because the channel conditions during the ABS processing period and outside the ABS processing period differ significantly depending on the presence or absence of interference, and measurements taken without distinguishing between the periods will result in an averagely poor CSI. These two types of CSI measurement data make it possible to understand the channel conditions of the satellite communication cell 132 and the 5G cell 112, respectively, and the impact of interference from both cells on the channel conditions, thereby improving the efficiency of communication by the communication device 2C according to the channel conditions.

[0058] The present invention has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and treatment processes, and that such modifications are also within the scope of the present invention.

[0059] The functional configuration of each device 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 other LSIs. Examples of software resources include operating systems, applications, and other programs. [Explanation of symbols]

[0060] 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 signal strength reduction unit, 32 orbit information acquisition unit, 33 communication delay acquisition unit, 34 synchronization unit, 35 satellite communication cell position acquisition unit, 111 5G base station, 112 5G cell, 121 4G base station, 122 4G cell, 131 communication satellite, 132 satellite communication cell, 133 gateway, A2 interference area.

Claims

1. A communication control method for controlling a ground-based network that is configured by a ground base station installed on the ground and that can communicate with a communication device in a ground communication cell provided to the ground by the ground base station using TN data that is continuous in time, and a non-ground-based network that is configured by a flying air base station and that can communicate with a communication device in a flying communication cell provided to the ground by NTN data that is continuous in time, a signal strength reducing step of reducing a signal strength of at least one of the TN data and the NTN data in at least an overlapping area of ​​the ground communication cell and the flight communication cell; a communication delay acquisition step of acquiring a communication delay between the flight base station and the flight communication cell; a synchronization step of synchronizing the TN data and the NTN data based on the communication delay acquired in the communication delay acquisition step; Equipped with A gateway capable of communicating with both the airborne base station and the ground base station is installed on the ground; The communication delay acquisition step acquires a delay in communication between the gateway and the flight communication cell via the flight base station. Communication control method.

2. 2. The communication control method according to claim 1, wherein the signal strength reducing step prohibits transmission of signals using at least a portion of the TN data and / or the NTN data in at least an overlapping area of ​​the ground communication cell and the flight communication cell.

3. 3. The communication control method according to claim 1, wherein the signal strength reducing step reduces the signal strength of a portion of the TN data at least in an overlapping area of ​​the ground communication cell and the flight communication cell.

4. The communication control method of claim 3, wherein the flying base station communicates with a communication device within an overlapping area of ​​the ground communication cell and the flying communication cell using the NTN data while the signal strength reduction step reduces the signal strength of the TN data.

5. 5. The communication control method according to claim 1, wherein said signal strength reducing step reduces the signal strength of the data in accordance with a predetermined pattern that specifies part of the data included in the data group.

6. Further comprising an orbit information acquisition step of acquiring orbit information of the flight base station, The communication delay acquisition step is executed by a communication device equipped with a positioning sensor capable of measuring its own position information, and calculates a communication delay between the flight base station and the communication device within the flight communication cell based on the position information of the communication device measured by the positioning sensor and the trajectory information of the flight base station acquired by the trajectory information acquisition step; The synchronization step causes the flying base station to transmit the NTN data earlier than the TN data transmitted by the ground base station by the communication delay calculated in the communication delay acquisition step.

6. A communication control method according to claim 1.

7. an orbit information acquisition step of acquiring orbit information of the flight base station; a flight communication cell position acquisition step of acquiring representative position information of the flight communication cell; Further provided with The communication delay acquisition step calculates a communication delay between the flight base station and the flight communication cell based on the representative position information of the flight communication cell acquired in the flight communication cell position acquisition step and the trajectory information of the flight base station acquired in the trajectory information acquisition step; The synchronization step causes the flying base station to transmit the NTN data earlier than the TN data transmitted by the ground base station by the communication delay calculated in the communication delay acquisition step.

7. A communication control method according to claim 1.

8. A communication control method described in any one of claims 1 to 7, wherein the synchronization step is executed by the terrestrial base station, and after the flying base station starts transmitting the NTN data, the start of transmission of the NTN data is delayed by the communication delay acquired by the communication delay acquisition step.

9. The communication control method according to claim 1 , wherein the communication delay acquisition step is executed by the terrestrial base station connected to the gateway.

10. Further comprising an orbit information acquisition step of acquiring orbit information of the flight base station, The communication delay acquisition step calculates a communication delay between the gateway and the flight base station based on the trajectory information of the flight base station acquired in the trajectory information acquisition step. The communication control method according to claim 9.

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