Network control device and program

Abstract

To achieve optimal wireless communication across the entire RAN.SOLUTION: A network control device controls a wireless communication network in which terminal devices communicate wirelessly with each other via a plurality of distributed access points, and includes an AP cluster identification unit that identifies an AP cluster indicating one or more access points that communicate wirelessly with the terminal devices, and a CPU selection unit that selects, for each AP cluster for each terminal device, a CPU to be connected to the access point included in the AP cluster.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a network control device and a program. [Background technology]

[0002] Conventionally, technology related to CF-mMIMO (Cell-Free massive Multi-Input Multi-Output) has been known. According to CF-mMIMO, each base station distributes multiple antennas and links these antennas to suppress the effects of interference between a terminal and multiple base stations. In addition, the base station transmits a reference signal to the terminal while sweeping a downlink beam in multiple directions. The terminal receives the reference signal and notifies the base station of the identifier of the best downlink beam that maximizes the received signal power. CF-mMIMO is disclosed, for example, in Non-Patent Document 1. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Emil Bjornson, Luca Sanguinetti, "Scalable Cell-Free Massive MIMO Systems" arXiv:1908.03119v2 [cs.IT] 8 May 2020 Summary of the Invention [Problem to be solved by the invention]

[0004] In the architecture shown in Non-Patent Document 1, an external controller calculates the cluster of access points and transmits it to the CPU. However, there is no description of a specific control scheme or interface, making it difficult for even those skilled in the art to realize it.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a network control device and a program that can realize suitable wireless communication throughout the entire RAN. [Means for solving the problem]

[0006] (1) One aspect of the present invention is a network control device that controls a wireless communication network in which terminal devices communicate with each other wirelessly via a plurality of distributed access points, and includes an AP cluster identification unit that identifies an AP cluster indicating one or more of the access points that communicate wirelessly with the terminal devices, and a CPU selection unit that selects, for each of the AP clusters for each of the terminal devices, a CPU to be connected to the access point included in the AP cluster. (2) Furthermore, one aspect of the present invention is that in the network control device of (1) above, the AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the multiple CPUs, and the RIC acquires transmission path and computer resource information from a distributed unit (O-DU), and then updates policy information of the AP cluster according to the usage status of the transmission path and computer. (3) Also, one aspect of the present invention is that in the network control device described above in (2), the RIC identifies the AP cluster after updating the policy information of the AP cluster, and notifies the distributed unit of the identified new AP cluster. (4) Furthermore, one aspect of the present invention is that in any of the network control devices described above in (1) to (3), an upper limit value of the access points that form the AP cluster is predetermined, and the AP cluster identification unit identifies the AP cluster within a range that does not exceed the predetermined upper limit value of the access points. (5) Furthermore, one aspect of the present invention is that in any of the network control devices described above in (1) to (4), a lower limit value of the wireless quality between the access point and the terminal device that can be used as the AP cluster is predetermined, and the AP cluster identification unit does not identify the access point as the AP cluster if the wireless quality falls below the predetermined lower limit value. (6) Furthermore, one aspect of the present invention is that in the network control device of (5) above, the terminal device and the access point perform beamforming on each other, and the wireless quality is the quality of the best beam that maximizes the received signal power as a result of the beamforming. (7) Furthermore, one aspect of the present invention is that in the network control device of (5) above, the terminal device and the access point perform beamforming on each other, and the wireless quality is determined based on the received signal power for each combination of the beam of the terminal device and the beam of the access point as a result of the beamforming. (8) Furthermore, one aspect of the present invention is a network control device according to (6) or (7) above, wherein the terminal device is equipped with multiple antennas that can be used simultaneously, and the multiple antennas equipped on the terminal device are each capable of outputting beams in different directions, and the AP cluster identification unit identifies the AP cluster based on the antennas that can be used simultaneously by the terminal device. (9) Furthermore, one aspect of the present invention is that in the network control device of any of (1) to (8) above, the AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the multiple CPUs, and the RIC recalculates the AP cluster and related parameters after obtaining radio quality information and service information from a distributed unit (O-DU). (10) Also, one aspect of the present invention is that in the network control device of (9) above, a list of access points to be used in the AP cluster is predetermined, and the AP cluster identification unit identifies the AP cluster according to the predetermined list of access points. (11) Furthermore, one aspect of the present invention is that in the network control device of (10) above, a list of the terminal devices to be used in the AP cluster is predetermined, and the AP cluster identification unit identifies the AP cluster according to the predetermined list of the terminal devices. (12) Furthermore, one aspect of the present invention is that in the network control device of any of (1) to (11) above, the AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the multiple CPUs, and the RIC acquires transmission power information indicating the transmission path and the power of the beam transmitted by the terminal device from a distributed unit (O-DU) at a different site, and performs pilot allocation calculations based on the acquired information. (13) Another aspect of the present invention is a program for executing a network control device that controls a wireless communication network in which terminal devices communicate wirelessly with each other via a plurality of distributed access points, the program executing an AP cluster identification step of identifying an AP cluster indicating one or more access points that communicate wirelessly with the terminal device, and a CPU selection step of selecting, for each AP cluster for each terminal device, a CPU to be connected to the access point included in the AP cluster. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a network control device and a program that can realize suitable wireless communication throughout the entire RAN. [Brief explanation of the drawings]

[0008] [Figure 1]FIG. 1 is a diagram illustrating a configuration of a wireless communication network according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a logical configuration of a wireless communication network according to the first embodiment. [Figure 3] 2 is a functional configuration diagram showing an example of the functional configuration of the network control device according to the first embodiment. FIG. [Figure 4] FIG. 10 is a sequence diagram showing a sequence when an AP cluster is calculated by a Near-RT RIC in the network control device according to the first embodiment. [Figure 5] FIG. 4 is a sequence diagram showing a sequence when an AP cluster is calculated in an O-DU in the network control device according to the first embodiment. [Figure 6] 1 is a diagram showing a logical configuration of a wireless communication network according to a first embodiment. [Figure 7] FIG. 4 is a diagram illustrating an example of an upper limit value of the number of access points that form an AP cluster according to the first embodiment. [Figure 8] FIG. 4 is a diagram illustrating an example of a lower limit value of wireless quality according to the first embodiment. [Figure 9] FIG. 2 is a diagram illustrating a first example of beamforming of a terminal device and an access point according to the first embodiment. [Figure 10] FIG. 2 is a diagram illustrating an example in which only the best beam is considered as the wireless quality according to the first embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example in which a plurality of beams is considered as wireless quality according to the first embodiment. [Figure 12] FIG. 10 is a diagram illustrating a second example of beamforming of a terminal device and an access point according to the first embodiment. [Figure 13] FIG. 10 is a sequence diagram showing an example of an interface for information related to an AP cluster change according to the first embodiment. [Figure 14] 1 is a diagram showing a logical configuration of a wireless communication network according to a first embodiment. [Figure 15]FIG. 4 is a diagram illustrating an example of a list of access points used in an AP cluster for each user according to the first embodiment. [Figure 16] FIG. 2 is a diagram showing an example of a list of spatially multiplexed users according to the first embodiment. [Figure 17] FIG. 2 is a diagram illustrating an example of optimization of an AP cluster depending on the RAN resource situation according to the first embodiment. [Figure 18] FIG. 2 is a diagram illustrating an example of optimization of an AP cluster in accordance with user movement according to the first embodiment. [Figure 19] FIG. 10 is a diagram illustrating a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. [Figure 20] FIG. 10 is a sequence diagram showing details of a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. [Figure 21] FIG. 11 is a first diagram showing a logical configuration of a wireless communication network for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to a second embodiment. [Figure 22] FIG. 11 is a first detailed sequence diagram showing details of a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. [Figure 23] FIG. 10 is a second diagram illustrating the logical configuration of a wireless communication network for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. [Figure 24] FIG. 10 is a second detailed sequence diagram showing details of the processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. [Figure 25] FIG. 11 is a configuration diagram illustrating beamforming in a first example according to a third embodiment. [Figure 26] FIG. 11 is a functional configuration diagram of a terminal in a first example according to a third embodiment. [Figure 27]13 is a communication quality table in a first example according to the third embodiment. [Figure 28] 10 is a diagram showing a beam table in a first example according to a third embodiment. [Figure 29] FIG. 11 is a sequence diagram of a first example according to the third embodiment. [Figure 30] FIG. 10 is a configuration diagram showing a combination of beams that can be used simultaneously by a terminal in a first example according to a third embodiment. [Figure 31] 31 is a beam table based on FIG. 30. [Figure 32] FIG. 11 is a configuration diagram illustrating beamforming in a second example according to the third embodiment. [Figure 33] FIG. 11 is a functional configuration diagram of a base station in a second example according to the third embodiment. [Figure 34] 13 is a communication quality table in a second example according to the third embodiment. [Figure 35] 10 is a beam table in a second example according to the third embodiment. [Figure 36] FIG. 1 is a diagram illustrating the configuration of a wireless communication network according to a conventional technique. [Figure 37] FIG. 10 is a diagram for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the conventional technology. DETAILED DESCRIPTION OF THE INVENTION

[0009] A network control device and a program according to an aspect of the present invention will be described in detail below with reference to preferred embodiments and the accompanying drawings. Note that the aspects of the present invention are not limited to these embodiments and include various modifications and improvements. In other words, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical, and the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention. Furthermore, in the drawings below, the scale and number of components may differ from the scale and number of the actual components to make each configuration easier to understand.

[0010] [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that, as a premise for the description of this embodiment, in a wireless communication network according to this embodiment, terminal devices communicate wirelessly with each other via access points. This embodiment assumes the use of Cell-Free massive MIMO (CF-mMIMO), which cooperatively uses a large number of antennas arranged in a wide communication area. This embodiment also assumes a mechanism in which signals from multiple distributed access points are processed by MU-MIMO (Multi-User MIMO) or the like at a base where the access points are aggregated.

[0011] Fig. 36 is a diagram for explaining the configuration of a wireless communication network according to the conventional technology. First, with reference to the same figure, the configuration of a wireless communication network 9 according to the conventional technology and problems will be explained. The wireless communication network 9 includes access points AP1 to AP8 and CPUs (Central Processing Units) 1 to CPU2. The same figure also shows terminal devices UE1 to UE4. Each terminal device performs wireless information communication with other terminal devices via an access point located nearby.

[0012] By performing beamforming, the terminal device and the access point search for a suitable beam (best beam) and perform concentrated information communication using a beam with a narrow wide-angle range. This configuration makes it possible to compensate for propagation loss. In the following description, a beam transmitted from a terminal device to an access point may be referred to as an uplink beam. Also, a beam transmitted from an access point to a terminal device may be referred to as a downlink beam. In the illustrated example, each terminal device transmits beams in four directions. Also, each access point transmits beams in eight directions. The reference signal contains the identifier # of that beam.

[0013] An AP cluster is configured as a group of access points consisting of one terminal device and one or more access points. In other words, an AP cluster includes one or more access points determined for each terminal device, and is a group of access points that transmit and receive wireless signals. In the example shown in the figure, AP clusters APC1 to APC4 are configured.

[0014] Specifically, in AP cluster APC1, terminal device UE1 transmits beam #1 and access point AP1 transmits beam #5 to communicate with each other, and terminal device UE1 transmits beam #3 and access point AP2 transmits beam #8 to communicate with each other. Also, in AP cluster APC2, terminal device UE2 transmits beam #4 and access point AP2 transmits beam #4 to communicate with each other, and terminal device UE2 transmits beam #2 and access point AP4 transmits beam #5 to communicate with each other. Also, in AP cluster APC3, terminal device UE3 transmits beam #1 and access point AP5 transmits beam #8 to communicate with each other, and terminal device UE3 transmits beam #2 and access point AP6 transmits beam #8 to communicate with each other. Furthermore, in AP cluster APC4, terminal device UE4 transmits beam #3, and access point AP6 transmits beam #3, thereby communicating information with each other; terminal device UE4 transmits beam #1, and access point AP7 transmits beam #8, thereby communicating information with each other; terminal device UE4 transmits beam #2, and access point AP8 transmits beam #8, thereby communicating information with each other.

[0015] Here, the terminal device includes information and communication devices such as smartphones, tablet devices, and wearable devices used by users. In other words, the terminal device is considered to move along with the user's movement. Therefore, as the user moves, the relative positional relationship between the terminal device and the access point is considered to change dynamically. However, according to conventional technology, it has been difficult to dynamically switch the access points included in an AP cluster as the user moves.

[0016] Furthermore, according to the prior art, when a terminal device exists between access points controlled by different CPUs, cooperation between CPU1 and CPU2 is not performed properly, resulting in a problem of degraded communication quality.

[0017] [First embodiment] 1 is a diagram for explaining the configuration of a wireless communication network according to a first embodiment. The configuration of the wireless communication network 1 according to the first embodiment will be explained with reference to the same figure. In this embodiment, the wireless communication network 1 differs from a wireless communication network 9 according to the conventional technology in that it includes a RAN Intelligent Controller (RIC) that controls the multiple CPUs. In the example shown in the figure, the RIC controls CPU1 and CPU2.

[0018] In the connection between the terminal device UE and the access point AP, according to this embodiment, the terminal device UE3 connects to a different destination. Specifically, in the AP cluster APC3, the terminal device UE3 further transmits beam #4, and the access point AP4 transmits beam #2, thereby performing information communication with each other. That is, the terminal device UE3 performs information communication with the access points AP4, AP5, and AP6.

[0019] Here, access point AP4 is controlled by CPU 1, and access points AP5 and AP6 are controlled by CPU 2. That is, terminal device UE3 is capable of communicating information with a plurality of access points controlled by different CPUs.

[0020] 2 is a diagram for explaining the logical configuration of a wireless communication network according to the first embodiment. In this embodiment, a terminal device connects to a plurality of access points, and therefore, it is necessary for each terminal device to determine which access point to transmit and receive data to and from. In addition, since the location of a terminal device changes from moment to moment, it is required to appropriately update the AP cluster.

[0021] As shown in the figure, wireless quality changes depending on how an AP cluster is formed. Wireless quality is significantly affected by the relative distance and orientation between a terminal device and an access point. For example, if an AP cluster is formed using terminal devices and access points that are not at a suitable relative distance or orientation, wireless quality may be degraded (even though a different combination could actually provide better wireless quality).

[0022] Furthermore, the transmission bandwidth changes depending on which CPU controls which access point, depending on the relationship between the CPUs and the access points. In other words, the transmission bandwidth changes depending on how the AP cluster is formed.

[0023] Furthermore, if access is concentrated on an access point controlled by a CPU, the load on that CPU may become uneven. In other words, the amount of computer resource consumption may change depending on how the AP cluster is formed.

[0024] According to this embodiment, by forming an AP cluster appropriately, it becomes possible to achieve various KPIs (Key Performance Indicators) such as wireless quality, transmission path bandwidth, and computer resource consumption. Furthermore, according to this embodiment, by controlling both the network and wireless on a per-user basis, it becomes possible to ensure communication quality for each user in any location.

[0025] 3 is a functional configuration diagram showing an example of the functional configuration of a network control device according to the first embodiment. An example of the functional configuration of the network control device 10 according to this embodiment will be described with reference to the same figure. The network control device 10 controls a wireless communication network 1. The network control device 10 may be included as part of the functions of an Open Radio Access Network (Open RAN, O-RAN or ORAN) architecture. The part of the functions of the O-RAN architecture may be, for example, a RAN Intelligent Controller (RIC).

[0026] The network control device 10 includes an AP cluster identification unit 11 and a CPU selection unit 12. The network control device 10 may include a CPU (not shown), a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory), etc., which are connected via a bus, and may function as a device including the AP cluster identification unit 11 and the CPU selection unit 12 by executing a network control program. Note that all or part of the functions of the network control device 10 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field-Programmable Gate Array).

[0027] The AP cluster identification unit 11 identifies an AP cluster. An AP cluster is identified for each terminal device. An AP cluster indicates one or more access points that communicate wirelessly with the terminal device. The number of access points included in an AP cluster may be, for example, about one to three. The AP cluster identification unit 11 identifies an AP cluster based on information acquired from the terminal device or the access point, for example.

[0028] The CPU selection unit 12 selects, for each AP cluster, a CPU to be connected to the access points included in the AP cluster. Here, the CPU may be a distributed unit (O-DU) in the O-RAN architecture. In the O-RAN architecture, the RIC uses a controller such as a non-real time (RT) RIC that controls at a cycle of 1 [sec] or more, or a near-real time (RT) RIC that controls at a cycle of 10 [msec] to 1 [sec], to instruct the O-DU on Massive MIMO parameter information. The CPU selection unit 12 selects, for each AP cluster, which CPU (O-DU) to connect the access points included in the AP cluster to.

[0029] In this embodiment, it is desired to control Massive MIMO so that various KPIs can be achieved in the entire wireless communication network 1, but currently there is a lack of an interface for collecting necessary information and issuing control instructions.

[0030] For example, there is a lack of an interface for AP cluster information. Currently, O-RAN does not define policy information or instruction formats, such as constraints and prerequisites for AP cluster formation based on the computer and transmission path resource status of each site. Therefore, it is difficult to form an AP cluster taking into account the computer and transmission path resources of each site. This can lead to a shortage of transmission paths and resources. Furthermore, when a terminal device performs beamforming, in CF-mMIMO, the terminal device's beam connects to multiple access points with different received signal powers at the access points and different best beams at that time. In such cases, it is not easy to appropriately determine beams between multiple combinations of access points and terminal devices simply by combining the best beams between the access points and terminal devices.

[0031] In addition, there is a lack of an interface for information related to AP cluster changes. Currently, O-RAN does not define the configuration information or command format for changing AP clusters. Therefore, it is not possible to change AP clusters or related MIMO parameter information using Near-RT RIC in response to user movement or service changes, which could result in a deterioration of wireless quality.

[0032] Considering the wide-area deployment of CF-mMIMO, there are issues with scalability because the computational load of transmission and reception processing and the transmission path load between the access point and the CPU are concentrated on a single CPU. Therefore, methods of distributing CPUs are being considered. In a distributed CPU environment, interference occurs between terminal devices connected to different CPUs (hereinafter referred to as inter-site UE interference), which may degrade the wireless quality of terminal devices located near the CPU boundary. To continuously provide the communication quality required for each application at every user location, it is necessary to suppress this inter-site interference.

[0033] Hereinafter, with reference to the drawings, an example of a specific implementation means when the network control device according to this embodiment is incorporated into the O-RAN architecture will be described.

[0034] First, specific means for solving the problem of insufficient interfaces for AP cluster information will be described with reference to Figures 4 to 12. Specifically, in this embodiment, a message instructing a change of policy information required when the Near RT RIC determines an AP cluster, and that policy information, are added to the interface between the Non-RT-RIC and the Near RT RIC (A1) and between the Non-RT-RIC and the O-DU (O1).

[0035] 4 is a sequence diagram showing a sequence when an AP cluster is calculated by a Near-RT RIC in a network control device according to the first embodiment. The diagram shows the processing of a Non-RT RIC (SMO), a Near-RT RIC, and an O-DU. The processing at each step will be explained below.

[0036] (Step S11) First, Data collection (O1) is transmitted from the O-DU to the Non-RT RIC. The information transmitted here includes information on transmission paths and computer resources, etc.

[0037] (Step S12) After acquiring transmission path and computer resource information from the O-DU, the Non-RT RIC changes the policy information of the AP cluster according to the usage status of the transmission path and computer.

[0038] (Step S13) Next, the Non-RT RIC transmits an Updated Configuration (A1) to the Near RT RIC. The Updated Configuration (A1) includes new messages and additional information. The information transmitted here includes AP cluster policy information and change instructions.

[0039] (Step S14) Upon receiving the Updated Configuration (A1) from the Non-RT RIC, the Near RT RIC recalculates the AP cluster based on the new AP cluster policy information.

[0040] (Step S15) After the AP cluster is recalculated, the Near RT RIC transmits an Updated Configuration (E2) to the O-DU. The transmitted information includes information regarding the instruction of the recalculated AP cluster.

[0041] Fig. 5 is a sequence diagram showing a sequence when an AP cluster is calculated in an O-DU in a network control device according to the first embodiment. As in Fig. 4, the figure shows the processing of a Non-RT RIC (SMO), a Near-RT RIC, and an O-DU. In the explanation given with reference to Fig. 5, the same steps as those in Fig. 4 are denoted by the same reference numerals, and explanations thereof may be omitted. Specifically, explanations of steps S11 and S12 will be omitted because similar processing is performed.

[0042] (Step S16) The Non-RT RIC transmits an Updated Configuration (O1) to the O-DU. The Updated Configuration (O1) includes new messages and additional information. The information transmitted here includes AP cluster policy information and change instructions.

[0043] (Step S17) When the O-DU receives the Updated Configuration (O1) from the Non-RT RIC, it recalculates the AP cluster based on the new AP cluster policy information.

[0044] 4 and 5, it is possible to change AP cluster policy information according to the usage status of resources (transmission paths and computers) of the entire RAN, and the Near RT RIC or O-DU (CPU) recalculates the AP cluster, thereby controlling resource consumption. Therefore, according to this embodiment, it is possible to prevent quality degradation due to resource shortages.

[0045] FIG. 6 is a diagram showing the logical configuration of a wireless communication network according to the first embodiment. This diagram shows the same logical configuration as the wireless communication network 1 shown in FIG. 2. Here, as the total number of access points forming an AP cluster increases, the amount of transmission path usage and the amount of computer resources usage increase. Therefore, in this embodiment, it is preferable to set an upper limit on the number of access points that can be used as an AP cluster. In this case, the upper limit of the number of access points that form an AP cluster is set in advance, and the AP cluster identification unit 11 can also be said to identify an AP cluster within a range that does not exceed the predetermined upper limit of access points.

[0046] By setting an upper limit on the number of access points that transmit and receive signals as an AP cluster, it is possible to prevent the total number of access points that form an AP cluster from increasing too much. As a result, it is possible to prevent an increase in the usage of transmission paths and computer resources due to an excessive increase in the total number of access points that form an AP cluster.

[0047] 7 is a diagram showing an example of the upper limit of the number of access points that form an AP cluster according to the first embodiment. In the diagram, an upper limit of the number of access points that form an AP cluster is set for each of CPU1 to CPU3. Specifically, the upper limit of the number of access points for CPU1 is 3, the upper limit of the number of access points for CPU2 is 3, and the upper limit of the number of access points for CPU3 is 3. In the example shown, the upper limit is the same regardless of the CPU, but may be different for each CPU.

[0048] Returning to FIG. 6, in this embodiment, there are cases where the connection between the access points forming the AP cluster and the terminal devices is below the expected quality. It is preferable to eliminate such connections below the expected quality. Therefore, in this embodiment, it is preferable to set a lower limit value for the wireless quality between the access points forming the AP cluster and the terminal devices. In this case, the lower limit value for the wireless quality between the access points and the terminal devices that can be used as an AP cluster is predetermined, and the AP cluster identification unit 11 can also be configured not to identify an access point as part of an AP cluster if the wireless quality falls below the predetermined lower limit value. Specifically, the signal-to-noise ratio (SINR) may be used as the wireless quality.

[0049] According to this embodiment, by setting a lower limit value of the wireless quality between the access points and the terminal devices that form the AP cluster, it is possible to prevent the wireless quality between the access points and the terminal devices from falling below the expected quality. Furthermore, according to this embodiment, it is possible to eliminate connections that are below the expected quality, so it is possible to reduce the consumption of computer resources and transmission path resources.

[0050] 8 is a diagram showing an example of a lower limit value of wireless quality according to the first embodiment. In the diagram, a lower limit value of wireless quality between an access point forming an AP cluster and a terminal device is set for each of CPU1 to CPU3. Specifically, the lower limit value of wireless quality for CPU1 is 10 [dB], the lower limit value of wireless quality for CPU2 is 5 [dB], and the lower limit value of wireless quality for CPU3 is 10 [dB]. As in the example shown in the figure, the lower limit value of wireless quality may be different for each CPU, or may be the same.

[0051] Here, the beam transmitted from the terminal device is taken into consideration when determining the wireless quality between the access points forming the AP cluster and the terminal device. Regarding the beam transmitted from the terminal device, only the best beam may be taken into consideration, or multiple candidates may be taken into consideration. Hereinafter, with reference to Figs. 9 to 12, an example of a beam taken into consideration when determining the wireless quality between the access points forming the AP cluster and the terminal device will be described.

[0052] 9 is a diagram showing a first example of beamforming of a terminal device and an access point according to the first embodiment. The diagram shows a terminal device UE1 and access points AP1 to AP3 present in the vicinity of the terminal device UE1. The access points AP1 to AP3 each sweep their own beams. In the example shown, each access point AP outputs beams #1 to #8. The terminal device UE1 measures the received signal power of the beams output from the access point AP while changing its own beam. The terminal device UE1 identifies the received signal power of the beams from the access point AP for each beam it outputs.

[0053] First, it is possible to consider only the best beam as the wireless quality. That is, the terminal device UE and the access point AP perform beamforming with each other, and the wireless quality in this case can be said to be the quality of the best beam that maximizes the received signal power as a result of beamforming. The terminal device UE1 notifies the best beam of each access point AP for the number of beams it outputs, and associates it with the index number of the beam it outputs. Each access point AP can know the best beam for the beam output by the terminal device UE1 and its received signal power. Through this processing, a beam between the terminal device UE1 and the access points AP1 to AP3 is determined.

[0054] 10 is a diagram showing an example of a case where only the best beam is considered as the wireless quality according to the first embodiment. In the diagram, each access point AP is associated with the best beam (the index of the beam output by the access point AP) for each beam output by the terminal device UE1, and the received signal power. Specifically, when the terminal device UE1 outputs beam #1, the best beam is beam #4 in relation to access point AP1, beam #4 in relation to access point AP2, and beam #7 in relation to access point AP3. When the terminal device UE1 outputs beam #2, the best beam is beam #3 in relation to access point AP1, beam #4 in relation to access point AP2, and beam #7 in relation to access point AP3. When the terminal device UE1 outputs beam #3, the best beam is beam #4 in relation to access point AP1, beam #5 in relation to access point AP2, and beam #1 in relation to access point AP3. When the terminal device UE1 outputs beam #3, the best beam is beam #4 in relation to access point AP1, beam #5 in relation to access point AP2, and beam #1 in relation to access point AP3. Furthermore, when the terminal device UE1 outputs beam #4, the best beam is beam #3 in relation to access point AP1, beam #2 in relation to access point AP2, and beam #4 in relation to access point AP3.

[0055] Returning to FIG. 9, it is next possible to consider multiple beams as the wireless quality. That is, the terminal device UE and the access point perform beamforming with each other, and the wireless quality can be determined based on the received signal power for each combination of the beam of the terminal device UE and the beam of the access point AP as a result of the beamforming. When multiple beams are considered as the wireless quality, the access points AP1 to AP3 each sweep their own beams. Next, each access point AP transmits an instruction regarding the number of beam candidates returned by the terminal device UE1 via a physical broadcast channel (PBCH) or the like. The terminal device UE1 measures the received signal power of the beam output from the access point AP while changing the beam it outputs. The terminal device UE1 identifies the received signal power of the beam from the access point AP for each beam it outputs.

[0056] The terminal device UE1 notifies the terminal device UE1 of beam candidates for each access point AP based on the conditions instructed by the access point AP, for the number of beams it outputs. At that time, the terminal device UE1 associates the index of the beam it outputs with the beam candidate of each access point AP. Through this process, each access point AP can know the beam candidate for the beam output by the terminal device UE1 and its received signal power.

[0057] 11 is a diagram showing an example of a case where multiple beams are considered as the wireless quality according to the first embodiment. In the diagram, each access point AP is associated with multiple beams (two in this case) for each beam output by the terminal device UE1, and received signal power. Specifically, when the terminal device UE1 outputs beam #1, the best beams are beam #4 and beam #5 in relation to access point AP1, beam #4 and beam #8 in relation to access point AP2, and beam #7 and beam #1 in relation to access point AP3. When the terminal device UE1 outputs beam #2, the best beams are beam #3 and beam #1 in relation to access point AP1, beam #4 and beam #5 in relation to access point AP2, and beam #7 and beam #8 in relation to access point AP3. When the terminal device UE1 outputs beam #3, the best beam is beam #4 in relation to access point AP1, beam #5 in relation to access point AP2, and beam #1 in relation to access point AP3. Furthermore, when the terminal device UE1 outputs beam #4, the best beam is beam #3 in relation to access point AP1, beam #2 in relation to access point AP2, and beam #4 in relation to access point AP3.

[0058] 12 is a diagram showing a second example of beamforming of a terminal device and an access point according to the first embodiment. The illustrated example shows an example in which the terminal device UE1 can use multiple beams simultaneously. In the second example, the terminal device UE1 is equipped with an antenna capable of outputting beams #1 and #2, and an antenna capable of outputting beams #3 and #4. That is, in the second example, the terminal device UE1 is equipped with multiple antennas capable of outputting multiple beams simultaneously. The multiple antennas equipped in the terminal device UE1 are each capable of outputting beams in different directions. In the illustrated example, the number of beams that the terminal device UE1 can use simultaneously is two, and the combinations that can be used simultaneously are beams #1 and #3, beams #1 and #4, beams #2 and #3, and beams #2 and #4. In this case, the AP cluster identification unit 11 identifies an AP cluster based on the antennas that the terminal device UE1 can use simultaneously.

[0059] Hereinafter, even when the terminal device UE1 can use multiple beams simultaneously, the processing procedures will be described for both the case where the best beam is considered as the wireless quality and the case where multiple beams are considered as the wireless quality.

[0060] A case will be described in which the best beam is considered as wireless quality. The access point AP sweeps its own beam. The terminal device UE1 measures the received signal power of the beam output from the access point AP while changing its own beam. The terminal device UE1 identifies the received signal power of the beam from the access point AP for each beam it outputs. The terminal device UE1 notifies the best beam of each access point AP for the number of beams it outputs, and associates it with the index number of the beam it outputs. Furthermore, the terminal device UE1 also notifies the number of beams it can use simultaneously and their combinations. Each access point AP can know the best beam for the beam output by the terminal device UE1, its received signal power, and the beams that the terminal device UE1 can use simultaneously. Through this processing, beams between the terminal device UE1 and access points AP1 to AP3 are determined.

[0061] A case where multiple beams are considered as wireless quality will be described. The access point AP sweeps its own beams. Each access point AP transmits an instruction regarding the number of beam candidates returned by the terminal device UE1 via a physical broadcast channel (PBCH) or the like. The terminal device UE1 notifies each access point AP of the best beam for the number of beams it outputs, and associates them with the index numbers of the beams it outputs. Furthermore, the terminal device UE1 also notifies the number of beams it can use simultaneously and their combinations. Each access point AP can know the best beam for the beams output by the terminal device UE1, its received signal power, and beams that the terminal device UE1 can use simultaneously. Through this process, beams between the terminal device UE1 and access points AP1 to AP3 are determined.

[0062] Next, specific means for solving the problem of a lack of interfaces for information related to AP cluster changes will be described with reference to Figures 13 to 16. Specifically, in this embodiment, an instruction message for changing AP clusters and related MIMO parameter information, as well as the AP clusters and parameter information, are added to the interface between Near-RT-RIC and O-DU (E2).

[0063] 13 is a sequence diagram showing an example of an interface for information related to an AP cluster change according to the first embodiment. The diagram shows the processing of the Non-RT RIC (SMO), Near-RT RIC, and O-DU. The processing in each step will be described below.

[0064] (Step S21) First, Data collection (O1) is transmitted from the O-DU to the Near-RT RIC. The information transmitted here includes user wireless quality information, service information, and the like.

[0065] (Step S22) After acquiring the wireless quality information and service information, the Near-RT RIC recalculates the AP cluster and related parameters.

[0066] (Step S23) Next, the Near-RT RIC transmits an Updated Configuration (E2) to the O-DU. The Updated Configuration (E2) includes a new message and additional information. The information transmitted here includes AP cluster information and a change instruction.

[0067] (Step S24) After receiving the Updated Configuration (E2), the O-DU calculates the weight of MU-MIMO based on the new AP cluster and related parameters.

[0068] By adopting this configuration, it is possible to change the AP cluster and MIMO parameters required for signal processing calculations in response to user movement and changes in services. It is also possible to provide wireless quality appropriate for the environment after movement and the services currently being used. Furthermore, it is possible to continuously ensure the communication quality desired by the user.

[0069] FIG. 14 is a diagram showing the logical configuration of a wireless communication network according to the first embodiment. The diagram shows the same logical configuration as the wireless communication network 1 shown in FIG. 2. Here, an example of information related to an AP cluster change is a list of access points used in an AP cluster for each user. In the example shown in the figure, the access points used in the AP cluster of the terminal device UE4 are access point AP5, access point AP6, and access point AP7. That is, according to this embodiment, the list of access points AP used in the AP cluster is predetermined, and the AP cluster identification unit 11 can also be said to identify the AP cluster according to the predetermined list of access points AP.

[0070] In this way, by defining a list of access points used in an AP cluster for each user as information related to an AP cluster change, the AP cluster for transmitting and receiving data to and from the terminal device UE can be changed to an AP cluster that can ensure the required wireless quality in accordance with user movement or service changes. Therefore, according to this embodiment, it is possible to continuously provide the communication quality desired by the user. Note that the wireless quality between the access point AP and the terminal device UE can be acquired using the method described with reference to FIGS. 9 to 12.

[0071] 15 is a diagram showing an example of a list of access points used in an AP cluster for each user according to the first embodiment. In the diagram, a list of access points forming an AP cluster is associated with each of terminal devices UE1 to UE4. Specifically, access points AP1 and AP2 are associated with terminal device UE1, access points AP2 and AP4 are associated with terminal device UE2, access points AP4, AP5, and AP6 are associated with terminal device UE3, and access points AP6, AP7, and AP8 are associated with terminal device UE4.

[0072] 14, an example of information related to an AP cluster change is a list of users who are spatially multiplexed into the same PRB (Physical Resource Block) during the same MU-MIMO signal processing. In the example shown in the figure, terminal apparatus UE1 and terminal apparatus UE2 are spatially multiplexed, and terminal apparatus UE3 and terminal apparatus UE4 are spatially multiplexed. That is, according to this embodiment, a list of terminal apparatuses UE to be used in an AP cluster is predetermined, and the AP cluster identification unit 11 can also be said to identify an AP cluster according to the predetermined list of terminal apparatuses UE.

[0073] In this way, by defining a list of spatially multiplexed users as information related to an AP cluster change, it becomes possible to control the combination of users to be spatially multiplexed in MU-MIMO in accordance with changes in the interference situation between users due to changes in the positional relationships between multiple users, etc. Therefore, according to this embodiment, continuous communication quality for users can be ensured.

[0074] 16 is a diagram showing an example of a list of spatially multiplexed users according to the first embodiment. In the figure, spatial multiplexing IDs are associated with a list of user IDs. Specifically, spatial multiplexing ID 1 is associated with terminal apparatus UE1 and terminal apparatus UE2, and spatial multiplexing ID 2 is associated with terminal apparatus UE3 and terminal apparatus UE4.

[0075] Next, a specific example of AP cluster optimization using the above-described embodiment will be described with reference to FIGS.

[0076] Fig. 17 is a diagram showing an example of optimization of an AP cluster depending on the RAN resource situation. With reference to the same figure, an example of optimization of an AP cluster depending on the RAN resource situation will be described. Fig. 17(A) is a diagram showing an example of the logical configuration of a wireless communication network 1, and Fig. 17(B) is a diagram showing an example of the functional configuration of an O-RAN architecture.

[0077] First, wireless quality information between the access point AP and the terminal device UE, RAN transmission path resource usage rate, computer resource usage rate, user spatial distribution, service usage status, etc. are acquired via the O1 interface. Next, the Non-RT RIC determines AP cluster policy information using mathematical programming or machine learning according to the KPI based on the collected RAN resource information and user service information. Here, examples of KPIs include the total throughput of each user, the throughput satisfaction level of each user, wireless resource usage rate, computer resource usage rate, and transmission path bandwidth usage rate.

[0078] Furthermore, the Non-RT RIC transmits AP cluster policy information and a change instruction to the Near-RT RIC using the AP cluster policy information interface described above. The Near-RT RIC then updates the AP cluster for each user using the updated AP cluster policy. Furthermore, the Near-RT RIC transmits a setting change instruction to the O-DU using the AP cluster change-related interface described above, and starts communication using the updated AP cluster.

[0079] In this way, the AP cluster is updated according to the RAN resource situation, and the usage situation of the computer and the usage situation of the transmission path are optimized. Here, users operating terminal devices UE may be present in different locations during the day and at night (for example, the density increases in business districts where many workplaces are located during the day, and the density increases in residential areas at night). Therefore, the distribution of terminal devices UE during the day and the distribution of terminal devices UE at night may differ from each other. According to this embodiment, the AP cluster can be updated in real time to a suitable AP cluster according to the respective distribution situations. Therefore, according to this embodiment, suitable wireless communication can be realized throughout the RAN.

[0080] Fig. 18 is a diagram showing an example of optimization of an AP cluster accompanying user movement according to the first embodiment. With reference to the same figure, an example of optimization of an AP cluster accompanying user movement will be described. Fig. 18(A) is a diagram showing an example of the logical configuration of a wireless communication network 1, and Fig. 18(B) is a diagram showing an example of a functional configuration diagram of an O-RAN architecture.

[0081] First, wireless quality information and user service information between the access point AP and the terminal device UE are acquired via the O1 interface. Next, the Near-RT RIC calculates AP cluster policy information and a list of users to be spatially multiplexed using MU-MIMO using mathematical programming or machine learning according to the KPIs based on the collected wireless quality information and user service information. Here, examples of KPIs include the total throughput of each user, the throughput satisfaction level of each user, the utilization rate of wireless resources, the utilization rate of computer resources, and the utilization rate of transmission path bandwidth.

[0082] Next, the AP cluster information is transmitted from the Near-RT RIC to the O-DU. This transmission is performed using the interface related to the AP cluster change described above. Optimal communication is initiated after a user moves using a new AP cluster for each user and MU-MIMO parameters. Therefore, according to this embodiment, even if a user moves, the AP cluster can be updated in real time to a suitable AP cluster. Therefore, according to this embodiment, suitable wireless communication can be realized throughout the RAN.

[0083] [Second embodiment] A second embodiment will be described with reference to Fig. 19 to Fig. 24. In the second embodiment, a processing procedure for suppressing interference between terminal devices UE present between different sites will be described. The second embodiment aims to continuously provide communication quality required for each application in any location where users are present. To achieve this aim, it is required to suppress interference between terminal devices UE at different sites (hereinafter, may be referred to as interference between different site UEs) occurring to users near the boundary between distributed CPUs.

[0084] Conventional technologies have been used to suppress interference between UEs at different sites by replicating and forwarding the main signal (IQ signal) to a CPU at another site and forming an AP cluster across CPUs at different sites. However, because the main signals (IQ signals) transmitted and received by each UE are aggregated at one site for wireless signal processing, the IQ signals must be transmitted to the BH between CPUs at different sites, which places a heavy load on the BH. This requires limiting the size of the AP cluster across sites so as not to exceed the BH capacity, which may result in incomplete elimination of interference between UEs at different sites. When a UE also performs beamforming, there is a problem that the beam cannot be appropriately determined by simply combining the best beam between the access point AP and the UE when the UE is connected to multiple access points, such as CF-mMIMO, where the received signal power of the access point AP and the best beam at that time vary depending on the UE's beam.

[0085] 37 is a diagram for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the conventional technology. With reference to the same figure, problems with the processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network 9 according to the conventional technology will be explained. In the same figure, the AP cluster of terminal device UE1 is made up of access points AP1 to AP6, and the AP cluster of terminal device UE2 is made up of access points AP7 to AP9. Here, there is an interference signal from terminal device UE1 to terminal device UE2 (access points AP7 and AP8).

[0086] According to the conventional technology, the RIC first calculates an AP cluster, with the wireless quality required for the user being within a range not exceeding the BH capacity. Here, the object of control of the RIC is the AP cluster that receives the main signal for each terminal device UE. In this case, IQ signals from access points AP5 and AP6 included in the AP cluster of the terminal device UE1 are transferred to and aggregated by the CPU1. The CPU1 performs channel estimation and signal processing for the terminal device UE1. Signals to access points AP that are not included in the AP cluster of the terminal device UE1, i.e., interference signals from the terminal device UE1 to access points AP7 and AP8, are treated as noise. For this reason, when the CPU2 calculates the weight for the terminal device UE2, it is not possible to separate the interference signal from the terminal device UE1, resulting in degradation of wireless quality.

[0087] Therefore, in this embodiment, each terminal device UE starts up a CPU that performs only channel estimation of same-site and different-site UE interference signals at multiple local sites to which access points AP that cause different-site UE interference are directly connected, and simultaneously performs channel estimation of different-site UE interference signals at each site. Next, using this estimated channel of the different-site UE interference signals, a weight calculation is performed to suppress different-site UE interference with the terminal device UE that performs main signal processing in the CPU of its own site.

[0088] Pilot allocation information of terminal devices UE that are sources of inter-site UE interference, which are necessary for channel estimation of inter-site UE interference signals at multiple sites, and a list of access points APs that perform channel estimation of inter-site UE interference are calculated by an external controller and transmitted to the CPU of each site. Note that the list of access points APs that perform channel estimation of inter-site UE interference is limited to access points APs that are sufficiently affected by the interference, and is not performed for access points APs whose interference is weak and unnecessary. Note that the wireless quality between the access points APs and the terminal devices UEs can be acquired using the methods described with reference to Figures 9 to 12.

[0089] 19 is a diagram for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. With reference to the diagram, a method for solving the above-mentioned problems will be explained.

[0090] First, the RIC performs calculations for the control objects. The control objects include AP clusters that transmit and receive main signals for each terminal device UE, pilot allocation information, beam information transmitted by the terminal device UE, and instructions to start up AP clusters and estimation CPUs that only perform channel estimation for each terminal device UE. After the calculations, the RIC issues instructions to each CPU.

[0091] Next, IQ signals of access points AP5 and AP6 included in the AP cluster of terminal device UE1 are transferred and aggregated to CPU 1. Subsequently, CPU 1 performs channel estimation and signal processing for terminal device UE1.

[0092] Furthermore, a channel estimation CPU1' for a different-site UE interference signal from the terminal device UE1 is started up at the local site, and channel estimation is performed. Subsequently, channel information is shared from the channel estimation CPU1' to the CPU2. The CPU2 calculates a weight for the terminal device UE2 using estimated channels between the terminal device UE1 and the access point AP7 and between the terminal device UE1 and the access point AP8. A minimum mean squared error (MMSE) criterion may be used in this calculation process. By separating the different-site UE interference signal from the terminal device UE1, it is possible to suppress interference from the terminal device UE1.

[0093] That is, according to this embodiment, there are access points AP (in the illustrated example, access points AP7 and AP8) that perform only channel estimation for the terminal device UE1. The access points AP use the estimated channels to calculate the weights for the terminal device UE2. Note that in the illustrated example, the interference from the terminal device UE1 to the access point AP9 is weak, so channel estimation is not performed.

[0094] It is also assumed that the terminal device UE2 also starts up a CPU 2' for channel estimation at site #1 in order to reduce interference with the terminal device UE1. However, in the explanation given with reference to the same figure, this explanation is omitted to avoid complicating the description.

[0095] According to this embodiment, channel estimation of an inter-site UE interference signal from a terminal device UE is performed simultaneously at multiple local sites to which the interfered access point AP is connected, and weight calculation for suppressing inter-site UE interference is performed at each local site using the estimated channel, thereby making it possible to suppress inter-site UE interference without transmitting an IQ signal to the BH between sites. In other words, it is possible to suppress inter-site UE interference over a wide area without expanding the AP cluster and increasing the BH load that accompanies this. Therefore, according to this embodiment, it is possible to know the best beam of the access point AP for the beam transmitted by the terminal device UE, and to select an appropriate beam. Therefore, according to this embodiment, it is possible to improve the quality of wireless communication.

[0096] 20 is a sequence diagram showing details of a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. The diagram shows the processing of a Non-RT RIC or Near-RT RIC (i.e., RIC) and an O-DU. The processing in each step will be described below.

[0097] (Step S31) First, Data Collection (O1) is transmitted from an O-DU at a different site to a RIC. The transmitted information includes information on the transmission power of the terminal device UE, propagation path information, and information on the beam of the terminal device UE. When multiple O-DUs exist, each O-DU transmits Data Collection (O1).

[0098] (Step S32) The RIC performs pilot allocation calculation based on the Data Collection (O1) acquired from multiple O-DUs at different sites. Details of this calculation will be described later with reference to FIGS. 21 and 22.

[0099] (Step S33) After calculating the pilot allocation, the RIC transmits an Updated Configuration (O1 or E2) to the O-DU. Here, the transmitted information includes pilot allocation information, information on the transmission power of the terminal device UE, a change instruction, information on the beam of the terminal device UE, etc. If there are multiple O-DUs, the RIC transmits an Updated Configuration (O1 or E2) to each O-DU.

[0100] (Step S34) Next, the RIC calculates the range of channel estimation for each user. Details of this calculation will be described later with reference to FIGS.

[0101] (Step S35) After calculating the pilot allocation, the RIC transmits an Updated Configuration (O1 or E2) to the O-DU. Here, the transmitted information includes a list of access points AP for which channels have been estimated for each user, a change instruction, information on the beam of the terminal device UE, etc. If there are multiple O-DUs, the RIC transmits an Updated Configuration (O1 or E2) to each O-DU.

[0102] (Step S36) The O-DU performs channel estimation based on the new pilot information and the list of access points AP. If there are multiple O-DUs, each O-DU performs channel estimation.

[0103] Next, the pilot allocation calculation in step S32 described above will be described in detail with reference to FIGS.

[0104] Fig. 21 is a first diagram showing a logical configuration of a wireless communication network for explaining a processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. Fig. 22 is a first detailed sequence diagram showing details of the processing procedure for suppressing interference between terminal devices at different sites using a wireless communication network according to the second embodiment. A detailed processing procedure for calculating pilot allocation will be explained with reference to Figs. 21 and 22.

[0105] Here, it is preferable that instruction forms for pilot allocation information and transmission power information of the terminal device UE be defined for inter-site channel estimation of an interference signal from a terminal device UE that is a source of inter-site interference. However, currently, there is no definition for these in the O-RAN architecture. Therefore, a CPU of a different site cannot distinguish a pilot signal of a terminal device UE that causes inter-site interference. In other words, currently, there is a problem that channel estimation of an interference signal is not possible.

[0106] Furthermore, when the terminal device UE also performs beamforming, it is conceivable that the terminal device UE will be connected to multiple access points AP such as CF-mMIMO, in which the received signal power of the access points AP and the best beam at that time differ depending on the beam of the terminal device UE. In such a case, there has been a problem in that it is not easy to appropriately determine the beam between the multiple access points AP and the terminal device UE simply by combining the best beam between the access points AP and the terminal device UE.

[0107] Therefore, in this embodiment, a message instructing addition and change of pilot allocation information and transmission power information for each terminal device UE and its parameter information are added to the interface between the Near-RT-RIC and O-DU (E2) or between the Non-RT-RIC and O-DU (O1) (which can be considered as the RIC and O-DU in the illustrated example).Using such an interface, the user transmission power and pilot allocation information for each terminal device UE are transmitted from the RIC to each site.

[0108] According to this embodiment, O-DU2' (vCPU2) performs channel estimation for the terminal device UE2 and access points AP1 to AP4, and O-DU1' (vCPU1) performs channel estimation for the terminal device UE1 and access points AP5 to AP8. That is, according to this embodiment, channel estimation across sites is realized. In this way, it is possible to calculate a weight for suppressing interference between UEs of different sites using the estimated channel.

[0109] Below, specific examples of the interface between Near-RT-RIC and O-DU (E2) and specific examples of the interface between Non-RT-RIC and O-DU (O1) will be explained.

[0110] First, a specific example of the interface between Near-RT-RIC and O-DU (E2) will be described. In this case, it is required to reduce the overhead caused by expanding pilot resources while preventing pilot contamination. Therefore, the Non-RT-RIC calculates the pilot sequence length according to the user density in the area so as to balance the degree of pilot contamination and the overhead of the pilot signal (including beam information of the terminal device UE). In this way, an interface is added to instruct the O-DU as the sequence length for each area.

[0111] By adding an interface that instructs the O-DU as the sequence length for each area, for example, in a certain area, during periods of high user density, the pilot sequence length can be extended, improving the directivity of pilots and preventing degradation of radio quality due to pilot contamination. Conversely, during periods of low user density, the pilot sequence length can be shortened, increasing the proportion of radio resources allocated to the main signal and improving frequency utilization efficiency. Since large changes in user density are expected to occur in periods of minutes to hours, it is preferable to utilize a Non-RT-RIC, which is suitable as a controller for the same period.

[0112] Next, a specific example of the interface between the Non-RT-RIC and the O-DU (O1) will be described. In this case, the interference situation between pilot signals of users changes due to user movement, and there is a problem that pilot contamination occurs between users to which the same pilot is assigned. Therefore, the Near RT-RIC calculates pilot allocation information (including beam information of the terminal equipment UE) each time so as to reduce pilot contamination based on the interference situation between users according to the user's movement. Furthermore, the calculated pilot allocation information for each terminal equipment UE is shared with all O-DUs that accommodate other terminal equipment UEs to which the terminal equipment UE may cause interference.

[0113] By adopting this configuration, pilot contamination can be reduced by instructing optimal pilot allocation according to changes in the interference situation between users due to user movement.In addition, channel estimation can be performed independently at all O-DUs that are subject to inter-site interference.Since channel fluctuations due to user movement are expected to occur in periods from milliseconds to seconds, it is preferable to utilize Near RT-RIC, which is suitable as a controller with the same period.

[0114] By defining the above-described interface, pilot allocation information is shared among a plurality of sites. Therefore, it is possible to perform channel estimation at a plurality of sites for an interference signal of a terminal device UE, which is a source of interference between different-site UEs. By using this estimation channel for interference between different-site UEs to perform weight calculation of MIMO for suppressing the interference signal at each site, it is possible to suppress interference between different-site UEs. That is, according to this embodiment, it is possible to know the best beam of the access point AP for the beam of the terminal device UE. Therefore, according to this embodiment, it is possible to select an appropriate beam for each of the access point AP and the terminal device UE, and it is possible to achieve quality improvement.

[0115] Next, the calculation of the range of channel estimation for each user in step S34 described above will be described in detail with reference to FIGS.

[0116] Fig. 23 is a second diagram of the logical configuration of a wireless communication network for explaining the processing procedure for suppressing interference between terminal devices at different sites using the wireless communication network according to the second embodiment. Fig. 24 is a second detailed sequence diagram showing details of the processing procedure for suppressing interference between terminal devices at different sites using the wireless communication network according to the second embodiment. With reference to Figs. 23 and 24, the detailed processing procedure for calculating the range of channel estimation for each user will be explained.

[0117] In this situation, when O-DUs (CPUs) are distributed across multiple sites, it is preferable to define a list of access points APs that perform only channel estimation for each terminal device UE, and a form of instruction for this. However, currently, the O-RAN architecture does not have any definitions for these. Therefore, there is a problem that the amount of calculation by the O-DU may increase due to channel estimation between access points APs and terminal devices UEs where interference between different sites is weak and interference cancellation is not required.

[0118] Furthermore, when the terminal device UE also performs beamforming, it is conceivable that the terminal device UE will be connected to multiple access points AP such as CF-mMIMO, in which the received signal power of the access points AP and the best beam at that time differ depending on the beam of the terminal device UE. In such a case, there has been a problem in that it is not easy to appropriately determine the beam between the multiple access points AP and the terminal device UE simply by combining the best beam between the access points AP and the terminal device UE.

[0119] Therefore, in this embodiment, a message instructing each site to change the list information of the access point AP that only performs channel estimation for each terminal device UE, and its parameter information, are added to the interface between Near-RT-RIC and O-DU (E2) or between Non-RT-RIC and O-DU (O1) (which can be considered as RIC and O-DU in the example shown).

[0120] The O-DU1′ performs channel estimation of interference between different-site UEs only between the designated access point AP and the terminal device UE. In this way, it is possible to calculate a weight for suppressing interference between different-site UEs using the estimated channel.

[0121] Furthermore, according to this embodiment, it is also possible to perform only channel estimation by A-DU2 between the terminal device UE1 and the access point AP7, and between the terminal device UE1 and the access point AP8. In other words, by narrowing down to only between the access point AP and the terminal device UE where different-site UE interference occurs, it is also possible to obtain an effect of suppressing the amount of calculation.

[0122] According to this embodiment, the O-DU (CPU) performs channel estimation only for the terminal device UE and the access point AP from which interference should be removed, depending on the interference situation between users, and can use this for weight calculation to suppress interference. Also, according to this embodiment, it is possible to prevent an increase in the amount of O-DU calculation due to channel estimation between the access point AP and the terminal device UEE where the interference signal is weak and interference removal is not required. Also, according to this embodiment, it is possible to know the best beam of the access point AP for the beam of the terminal device UE. Therefore, according to this embodiment, it is possible to select an appropriate beam for each of the access point AP and the terminal device UE, and to achieve quality improvement.

[0123] [Third embodiment] A third embodiment will be described with reference to Figures 25 to 34. In the third embodiment, a specific aspect of a method for acquiring wireless quality between an access point AP and a terminal device UE, as described with reference to Figures 9 to 12, will be described. The third embodiment can also be said to be a specific method for ensuring wireless quality, as described with reference to Figures 9 to 12. Note that in the description of the third embodiment, reference numerals are newly assigned, and therefore may overlap with the reference numerals of the above-mentioned embodiments.

[0124] The third embodiment will be described in the following two examples. Example 1 When one terminal is connected to multiple base stations at the same time, the combination of multiple uplink beams from the terminal and multiple downlink beams from each of the multiple base stations is used. <Example 2> When one base station communicates with multiple terminals at the same time, the combination of multiple downlink beams from the base station and multiple uplink beams from each of the multiple terminals is used.

[0125] Example 1 FIG. 25 is a configuration diagram illustrating beamforming in a first example according to the third embodiment of the present invention.

[0126] According to FIG. 25, when one terminal is connected to multiple base stations at the same time, it represents a combination of multiple uplink beams of the terminal and multiple downlink beams of each of the multiple base stations. The system of FIG. 25 includes a terminal 1, three base stations 21 to 23, and a base station control device 3. The terminal 1 has a beamforming-compatible multi-antenna capable of transmitting uplink beams in multiple directions, and communicates simultaneously with multiple base stations 2. Here, the transmission beam from the terminal 1 is referred to as an "uplink beam." According to Fig. 25, the multi-antenna of terminal 1 is capable of transmitting uplink beams #1 to #4 in each of four directions. The multi-antenna transmits reference signals of the uplink beams in different directions while performing beam sweeping. The reference signals include the identifier # of the uplink beam.

[0127] Each of the base stations 21 to 23 also has a beamforming-compatible multi-antenna capable of transmitting downlink beams in multiple directions, and communicates simultaneously with the terminal 1. Here, the transmission beam from each of the base stations 21 to 23 is referred to as a "downlink beam." 25, the multi-antennas of the base stations 21 to 23 are each capable of transmitting downlink beams #1 to #8 in eight directions. The multi-antennas transmit reference signals for the downlink beams in different directions while performing beam sweeping. The reference signals include the identifier # of the downlink beam.

[0128] The base station control device 3 controls each of the base stations 21 to 23 by determining the best downlink beam for communication with the terminal 1. The base station control device 3 also manages the uplink beam of the terminal 1.

[0129] FIG. 26 is a functional configuration diagram of a terminal in a first example according to the third embodiment of the present invention.

[0130] 26, terminal 1 has a multi-antenna 100, as well as a communication quality measurement unit 101, a downlink best beam selection unit 102, an uplink best beam selection unit 103, an uplink beam control unit 104, a beam table notification unit 105, and an uplink beam notification unit 106. These functional components other than the multi-antenna are realized by executing a program that causes a computer installed in the terminal to function. The processing flow of these functional components can also be understood as a beam selection method in a terminal having multiple antennas.

[0131] [Communication Quality Measurement Unit 101] The communication quality measurement unit 101 measures the communication quality of a plurality of downlink beams from each base station 2 for each uplink beam in a different direction at the terminal 1. The communication quality may be, for example, received signal power.

[0132] FIG. 27 is a communication quality table in a first example according to the third embodiment of the present invention. 27, the received signal power (communication quality) for each of the uplink beams #1 to #4 of the terminal 1 and the downlink beams #1 to #8 of the base stations 21 to 23 is shown.

[0133] [Downstream best beam selection unit 102] The best downlink beam selector 102 selects, for each uplink beam in a different direction in the terminal 1, a "best downlink beam" from among a plurality of downlink beams in each base station, whose communication quality satisfies a predetermined condition or higher. The "predetermined condition" for selecting the best downlink beam may be, for example, the selection of the downlink beam with the highest communication quality.

[0134] 27, for example, for the uplink beam #1 of terminal 1, downlink beam #1 having the highest communication quality is selected as the best downlink beam among downlink beams #1 to #8 in base station 21. Similarly, next, for the uplink beam #1 of terminal 1, downlink beam #4 having the highest communication quality is selected as the best downlink beam among downlink beams #1 to #8 in base station 22. Furthermore, for the uplink beam #2 of the terminal 1, the downlink beam #3 having the highest communication quality is selected as the best downlink beam among the downlink beams #1 to #8 of the base station 21.

[0135] [Uplink best beam selection unit 103] The uplink best beam selector 103 selects, from among a plurality of uplink beams for the terminal 1, a "uplink best beam" such that the sum of the communication qualities of the downlink best beams for all base stations 2 is equal to or exceeds a predetermined condition. The "predetermined condition" for selecting the best uplink beam may be, for example, selecting the downlink beam with the highest communication quality.

[0136] According to FIG. 27, for example, among a plurality of uplink beams #1 to #4 for the terminal 1, the sum of the communication qualities of the best downlink beams for all base stations 2 is calculated. According to the uplink beam #1 of terminal 1, the sum of the communication qualities of the downlink beam #1 of base station 21, the downlink beam #4 of base station 22, and the downlink beam #7 of base station 23 is calculated as the best downlink beam. Similarly, according to the uplink beam #2 of terminal 1, the sum of the communication qualities of the downlink beam #3 of base station 21, the downlink beam #4 of base station 22, and the downlink beam #4 of base station 23 is calculated as the best downlink beam. Ultimately, the uplink beam #2 of the terminal 1, which has the highest sum of communication qualities of the best downlink beams in all base stations 2, is selected as the "best uplink beam."

[0137] [Uplink beam control unit 104] The uplink beam control unit 104 controls the multi-antenna 100 so as to communicate with a plurality of base stations 2 simultaneously using the "best uplink beam."

[0138] [Beam Table Notification Unit 105] The beam table notification unit 105 creates a "beam table" that associates the identifiers of a plurality of uplink beams of the terminal 1 with the identifiers of the best downlink beams of each base station.

[0139] The beam table can be used for beam management, for example. Based on the technical specifications for beam management, the following controls are defined: Beam determination: Selecting the transmit beam / receive beam Beam measurement: Communication quality of the received signal of the beam Beam reporting: Reporting beam information Beam sweeping: Sweeping a spatial area (e.g., 360 degrees)

[0140] FIG. 28 shows a beam table in a first example according to the third embodiment of the present invention.

[0141] 28, a plurality of uplink beams #1 to #4 are arranged in a vertical row for the terminal 1. Each uplink beam is associated with an identifier of the best downlink beam for each of the base stations 21 to 23. According to FIG. 28, for example, the following beam table is created. The uplink beam #1 of the terminal 1 is associated with the identifier of the best downlink beam #1 having the highest received signal strength among the best downlink beams received from the base station 21. Of the best downlink beams received from the base station 21, the identifier of the best downlink beam #3 having the highest received signal strength is associated with the uplink beam #2 of the terminal 1. The identifier of the best downlink beam #4, which has the highest received signal strength among the best downlink beams received from the base station 21, is associated with the uplink beam #3 of the terminal 1. Of the best downlink beams received from the base station 21, the identifier of the best downlink beam #2 having the highest received signal strength is associated with the uplink beam #4 of the terminal 1. ... In this way, when viewed from the terminal 1, the other base stations 21 and 23 can be associated in the same way.

[0142] Furthermore, the beam table notification unit 105 may further associate the "communication quality" of the best downlink beam from each base station 2 with each of the identifiers #1 to #4 of the uplink beam of the terminal 1 in the beam table.

[0143] Then, the beam table notification unit 105 notifies the base station control device 3 of the beam table via the base station 2. Depending on the uplink beam selected by the terminal 1, the base station control device 3 can know which of the best downlink beams from each of the base stations 21 to 23 should be selected to improve communication quality.

[0144] [Upstream beam notification unit 106] The uplink beam notification unit 106 notifies each base station 2 of the identifier of the uplink beam of the terminal 1 and the identifier of the best downlink beam of the base station corresponding to the identifier of the uplink beam.

[0145] FIG. 29 is a sequence diagram of a first example according to the third embodiment of the present invention.

[0146] The uplink beam notification unit 106 notifies each base station 2 of the identifier of the best uplink beam selected for the terminal 1.

[0147] FIG. 30 is a configuration diagram showing a combination of beams that can be used simultaneously by a terminal in a first example according to the third embodiment of the present invention.

[0148] 30, it is assumed that terminal 1 has a plurality of multi-antennas 100. Terminal 1 can simultaneously transmit a plurality of uplink beams. In this case, the beam table notification unit 105 further notifies the terminal 1 of a combination of identifiers of uplink beams that can be transmitted simultaneously, among a plurality of uplink beams for the terminal 1. Number of beams that can be used simultaneously: 2 Simultaneous use possible combinations (Upstream beam #1, Upstream beam #3) (Up beam #1, Up beam #4) (Up beam #2, Up beam #3) (Up beam #2, Up beam #4)

[0149] FIG. 31 is a beam table based on FIG.

[0150] The above-mentioned downlink best beam selection unit 102 may select one or more downlink best beams that satisfy a communication quality that meets or exceeds a predetermined condition. For example, when the communication quality is the received signal power, the following predetermined conditions can be set to select multiple best downlink beams. (Predetermined condition 1) Up to xx downlink beams in descending order of received signal power (Prescribed condition 2) Downlink beam with received signal power of yy dBm or more (Prescribed condition 3) Up to xx downlink beams with received signal power of yy dBm or more As a result, in the beam table of FIG. 31, compared to the beam table of FIG. 28, one or more best downlink beams are associated with each uplink beam of terminal 1.

[0151] The beam table in FIG. 31 also includes combinations of beams that can be used simultaneously by terminal 1 in FIG. As a result, the base station control device 3 that has received the beam table can know the best downlink beam with high communication quality for the base station 2 for each simultaneously usable beam for the terminal 1.

[0152] <Example 2> FIG. 32 is a configuration diagram illustrating beamforming in a second example according to the third embodiment of the present invention.

[0153] Compared with FIG. 25, FIG. 32 shows a combination of multiple downlink beams of the base station and multiple uplink beams of each of the multiple terminals when one base station 2 communicates with multiple terminals simultaneously. The terminal 1 has a beamforming-compatible multi-antenna capable of transmitting uplink beams in multiple directions. The functions of the terminal 1, base station 2, and base station control device 3 are exactly the same as those in FIG.

[0154] FIG. 33 is a functional configuration diagram of a base station in a second example according to the third embodiment of the present invention.

[0155] 33, the base station 2 has a communication quality measurement unit 201, an uplink best beam selection unit 202, a downlink best beam selection unit 203, a downlink beam control unit 204, a beam table notification unit 205, and a downlink beam notification unit 206, in addition to a multi-antenna 200. These functional components other than the multi-antenna are realized by executing a program that causes a computer installed in the base station to function. The processing flow of these functional components can also be understood as a beam selection method in a base station having multiple antennas. Comparing FIG. 33 with the previously described FIG. 26, the following functions are relatively the same. <Device side in Figure 26> <-> <Base station side in Figure 33> Communication quality measurement unit 101 Communication quality measurement unit 201 Downstream best beam selector 102 Upstream best beam selector 202 Uplink best beam selector 103 Downlink best beam selector 203 Uplink beam control unit 104 Downlink beam control unit 204 Beam table notification unit 105 Beam table notification unit 205 Uplink beam notification unit 106 Downlink beam notification unit 206

[0156] [Multi-Antenna 200] The multi-antenna 200 is compatible with beamforming and can transmit downlink beams in multiple directions.

[0157] [Communication Quality Measurement Unit 201] The communication quality measurement unit 201 measures the communication quality of a plurality of uplink beams from each of the terminals 11 to 13 for each downlink beam in a different direction in the base station 2.

[0158] FIG. 34 is a communication quality table in a second example according to the third embodiment of the present invention. According to FIG. 34, downlink beams #1 to #8 in different directions in the base station 2 are associated with the received signal power (communication quality) of a plurality of uplink beams #1 to #4 from each of the terminals 11 to 13.

[0159] [Uplink best beam selection unit 202] The uplink best beam selector 202 selects, for each of the terminals 11 to 13, from among the multiple uplink beams for each downlink beam in a different direction, the uplink best beam that satisfies a communication quality that meets or exceeds a predetermined condition. 34, for example, for downlink beam #1 of base station 2, uplink beam #1 having the highest communication quality is selected as the best uplink beam among uplink beams #1 to #4 in terminal 11. Similarly, next, for downlink beam #1 of base station 2, uplink beam #4 having the highest communication quality is selected as the best uplink beam among downlink beams #1 to #4 in terminal 12. Furthermore, for the downlink beam #2 of the base station 2, the uplink beam #3 having the highest communication quality among the uplink beams #1 to #4 in the terminal 11 is selected as the best uplink beam. The uplink best beam selector 202 may select one or more uplink best beams that satisfy a predetermined condition or higher in communication quality.

[0160] [Downstream best beam selection unit 203] The downlink best beam selector 203 selects, from among a plurality of downlink beams in the base station 2, a downlink best beam that satisfies a predetermined condition or higher in the sum of the communication qualities of the uplink best beams in all terminals 1. According to FIG. 34, for example, among a plurality of uplink beams #1 to #8 in the base station 2, the sum of the communication qualities of the best downlink beams for all terminals 1 is calculated. According to downlink beam #1 of base station 2, the sum of the communication qualities of uplink beam #1 of terminal 11, uplink beam #4 of terminal 12, and uplink beam #3 of terminal 13 is calculated as the best uplink beam. Similarly, according to downlink beam #2 of base station 2, the sum of the communication qualities of uplink beam #3 of terminal 11, uplink beam #4 of terminal 12, and uplink beam #4 of terminal 13 is calculated as the best uplink beam. Ultimately, the downlink beam #2 of the base station 2, which has the highest sum of communication qualities of the downlink best beams for all the terminals 11 to 13, is selected as the "downlink best beam."

[0161] The downlink beam control unit 204 controls the multi-antenna 200 with the selected best downlink beam.

[0162] [Beam Table Notification Unit 205] The beam table notification unit 205 notifies the base station control device 3 of a beam table in which the identifiers of the downlink beams of the base station are associated with the identifiers of the best uplink beams of each terminal.

[0163] FIG. 35 shows a beam table in a second example according to the third embodiment of the present invention.

[0164] According to FIG. 35, for example, the following beam table is created. The downlink beam #1 of the base station 2 is associated with the identifier of the best uplink beam #1 having the highest received signal strength among the best uplink beams received from the terminal 11. The downlink beam #2 of the base station 2 is associated with the identifier of the best uplink beam #3, which has the highest received signal strength among the best uplink beams received from the terminal 11. The downlink beam #8 of the base station 2 is associated with the identifier of the best uplink beam #2 having the highest received signal strength among the best uplink beams received from the terminal 11.

[0165] Furthermore, the beam table notification unit 205 may associate the beam table with identifiers of one or more best uplink beams for each terminal. Furthermore, the beam table notification unit 205 may further associate the communication quality of the best uplink beam for each terminal with each identifier of the downlink beam of the base station in the beam table. Furthermore, the beam table notification unit 205 may further notify a combination of identifiers of downlink beams that can be transmitted simultaneously from among a plurality of downlink beams in the base station.

[0166] [Downstream beam notification unit 206] The downlink beam notification unit 206 notifies each terminal 1 of the identifier of the downlink beam of the base station 2 and the identifier of the best uplink beam for the terminal corresponding to the identifier of the downlink beam.

[0167] As described above in detail, according to the terminal, base station, and program of the present invention, when multiple connections are made simultaneously between the terminal and the base station, the optimal combination of uplink beams and downlink beams in beamforming can be selected.

[0168] Furthermore, the above-described embodiment makes it possible to, for example, "effectively utilize wireless resources between terminals and base stations," thereby contributing to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0169] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present invention.

[0170] In addition, a computer program for realizing the functions of each of the above-described devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. Note that the "computer system" here may also include hardware such as an OS and peripheral devices. In addition, "computer-readable recording medium" refers to writable non-volatile memory such as a flexible disk, optical magnetic disk, ROM, or flash memory, portable media such as a DVD (Digital Versatile Disc), or a storage device such as a hard disk built into a computer system.

[0171] Furthermore, the term "computer-readable recording medium" also includes a storage medium that stores a program for a certain period of time, such as a volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that serves as a server or client when the program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may also be transmitted from a computer system that stores the program in a storage device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may also be a program that realizes part of the aforementioned functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the aforementioned functions in combination with a program already stored in the computer system. [Explanation of symbols]

[0172] 1... wireless communication network, AP... access point, UE... terminal device, 10... network control device, 11... AP cluster identification unit, 12... CPU selection unit

Claims

1. A network control device that controls a wireless communication network in which terminal devices communicate with each other via a plurality of distributed access points, an AP cluster identification unit that identifies an AP cluster indicating one or more of the access points that perform wireless communication with the terminal device; a CPU selection unit that selects, for each of the AP clusters for each of the terminal devices, a CPU to be connected to the access point included in the AP cluster; A network control device comprising:

2. The AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the plurality of CPUs, The RIC acquires information on transmission paths and computer resources from the distributed unit (O-DU), and then updates the policy information of the AP cluster according to the usage status of the transmission paths and computers. The network control device according to claim 1 .

3. After the policy information of the AP cluster is updated, the RIC identifies the AP cluster and notifies the distributed unit of the identified new AP cluster. The network control device according to claim 2 .

4. an upper limit number of the access points that form the AP cluster is determined in advance; the AP cluster identification unit identifies the AP cluster within a range not exceeding a predetermined upper limit value of the access points; The network control device according to claim 1 .

5. a lower limit value of wireless quality between the access point and the terminal device that can be used as the AP cluster is determined in advance; the AP cluster identification unit does not identify the access point as part of the AP cluster if the wireless quality is below a predetermined lower limit value; The network control device according to claim 1 .

6. the terminal device and the access point perform beamforming with each other, The wireless quality is the quality of a best beam that maximizes received signal power as a result of beamforming. The network control device according to claim 5 .

7. the terminal device and the access point perform beamforming with each other, The wireless quality is determined based on received signal power for each combination of a beam of the terminal device and a beam of the access point as a result of beamforming. The network control device according to claim 5 .

8. The terminal device is provided with a plurality of antennas that can be used simultaneously, the plurality of antennas included in the terminal device are each capable of outputting beams in different directions; The AP cluster identification unit identifies the AP cluster based on antennas that can be used simultaneously by the terminal device.

8. The network control device according to claim 6 or 7.

9. The AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the plurality of CPUs, The RIC recalculates the AP cluster and related parameters after obtaining radio quality information and service information from the distributed unit (O-DU); The network control device according to claim 1 .

10. a list of the access points to be used for the AP cluster is predetermined; the AP cluster identification unit identifies the AP cluster according to a predetermined list of the access points; The network control device according to claim 9 .

11. a list of the terminal devices to be used in the AP cluster is determined in advance; the AP cluster identification unit identifies the AP cluster according to a predetermined list of the terminal devices. The network control device according to claim 9 .

12. The AP cluster identification unit and the CPU selection unit are included in a RAN Intelligent Controller (RIC) that controls the plurality of CPUs, The RIC acquires transmission power information indicating the power of the transmission path and the beam transmitted by the terminal device from a distributed unit (O-DU) at a different site, and performs pilot allocation calculation based on the acquired information. The network control device according to claim 1 .

13. A program for causing a network control device to execute a network control device that controls a wireless communication network in which terminal devices communicate with each other via a plurality of distributed access points, an AP cluster identification step of identifying an AP cluster indicating one or more of the access points that perform wireless communication with the terminal device; a CPU selection step of selecting, for each of the AP clusters for each of the terminal devices, a CPU to be connected to the access point included in the AP cluster; A program that executes the following.

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