Control device for setting relay device taking into consideration load on base station device and control method thereof, base station device and communication method thereof, and program

Abstract

To suppress an increase in load on a base station device that a repeater relays.SOLUTION: A control device acquires, from a plurality of base station devices, information that can identify a load due to a first terminal device directly connected to each of the plurality of base station devices and a load due to a second terminal device connected via a relay station to each of base station devices whose communication is relayed by the relay station among the plurality of base station devices, and based on information about each of the plurality of base station devices, determines whether to change the base station devices whose communication the relay station relays. If it is determined that a base station device whose communication the relay station relays is to be changed, the control device controls the relay station to point its beam in a direction of a base station device after the change.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a technique for operating a relay device in a wireless communication system. [Background technology]

[0002] In order to meet the increasing demand for cellular communications, the use of high frequency bands such as the 28 GHz band, which allows for easy securing of signal bandwidth, is being considered. Radio waves in such high frequency bands have large propagation losses and are strongly affected by obstacles. For this reason, in order to ensure sufficient area coverage, it is necessary to place many base station devices densely. However, installing such a large number of base station devices significantly increases costs. In contrast, by using repeaters such as wireless repeaters, it is possible to ensure area coverage at a relatively low cost. Summary of the Invention [Problem to be solved by the invention]

[0003] The terminal device is connected to the base station device via a repeater, and the repeater amplifies the radio signal transmitted by the base station device and relays it to the terminal device, and also amplifies the radio signal transmitted by the terminal device and relays it to the base station device. In this way, the base station device can accommodate both the terminal device directly connected thereto and the terminal device connected thereto via a repeater. As a result, for example, if the repeater relays the communication of a base station device with a large number of directly connected terminal devices, the load on the base station device increases, which may lead to a decrease in throughput and an increase in delay in the terminal device. [Means for solving the problem]

[0004] The present invention provides a technique for suppressing an increase in the load on a base station device that is a relay target of a repeater.

[0005] A control device according to one embodiment of the present invention has an acquisition means for acquiring information from a plurality of base station devices that can identify the load due to a first terminal device directly connected to each of the plurality of base station devices and the load due to a second terminal device connected via a relay station to each of the plurality of base station devices whose communications are relayed by a relay station, a decision means for deciding whether to change the base station device to which the relay station relays communications based on the information for each of the plurality of base station devices, and a control means for controlling the relay station to direct its beam in the direction of the changed base station device when it is determined that the base station device to which the relay station relays communications will be changed.

[0006] A base station device according to one embodiment of the present invention is a base station device having a function of a Distributed Unit (DU) of an Open-Radio Access Network (O-RAN), and has a notification means for notifying a control device having a function of the O-RAN's SMO (Service Management and Orchestration), using an O1 interface of the O-RAN, of information capable of identifying a load due to a first terminal device directly connected to the base station device and, when communication of the base station device is relayed by a relay station, a load due to a second terminal device connected via the relay station. Effect of the Invention

[0007] According to the present invention, it is possible to suppress an increase in the load on a base station device that is a relay target of a repeater. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 11 is a diagram illustrating an example of information collected in a base station device. [Diagram 3] FIG. 4 is a diagram illustrating an example of information acquired in the control device. [Figure 4] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station device and a control device. [Diagram 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Figure 6] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device. [Figure 7] FIG. 2 is a diagram outlining the flow of processing executed in a wireless communication system. [Figure 8] 11 is a diagram illustrating an example of a flow of a process executed by the control device to determine whether or not a relay target needs to be changed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] (System Configuration) FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. In the wireless communication system of FIG. 1, a base station device 101 and a base station device 102 each form a cell having a different physical cell identifier (PCI). FIG. 1 shows an example in which the base station device 101 forms a cell with PCI=1, and the base station device 102 forms a cell with PCI=2. The base station device 101 and the base station device 102 can form a plurality of beams that transmit different synchronization signal blocks (SSBs). In FIG. 1, the base station device 101 and the base station device 102 each form beams with SSB identifiers (SSB IDs) of 1 to 3. Then, a terminal device located within the range of at least one of the cells formed by each base station device can connect to the base station device using one of the beams formed by the base station device and communicate. By forming a beam with a narrow beam width and a high peak gain, the communicable distance from the base station device can be extended. In the following discussion, it is assumed that the base station device forms a plurality of beams, but beam formation is not essential. That is, in the following discussion, control that takes into account the load of each base station device is described, so beam formation is not necessarily required. On the other hand, the following discussion may be performed as control that takes into account the load of each beam.

[0011] In the wireless communication system according to the present embodiment, a relay station 103, which is a relay device such as a wireless repeater, is used. The relay station 103 relays communication between a base station device and a terminal device. The relay station 103 is capable of forming a beam. For example, in FIG. 1, the relay station 103 is arranged at a position where it can transmit and receive signals between both the base station device 101 and the base station device 102, and is configured to be able to switch the base station device to which the communication is to be relayed by directing a beam to one of the two. FIG. 1 shows a state in which the relay station 103 directs a beam, for example, toward the base station device 101 and relays communication by a beam of SSB ID=3 formed by the base station device 101. The relay station 103 can also direct a beam, for example, toward the base station device 102 and relay communication by a beam of SSB ID=1 formed by the base station device 102. In this way, in the present embodiment, it is assumed that the relay station 103 can change the base station device to which the communication is to be relayed.

[0012] The base station device 101 and the base station device 102 are configured to be able to communicate with the control device 111. For example, the base station device 101 and the base station device 102 are connected to the control device 111 using a wired line, and can transmit and receive information. The control device 111 is configured to collect information from the base station device 101 and the base station device 102, for example, and control the entire network. For example, the control device 111 can change the base station device to be relayed at each relay station via a management device 112 that manages the relay stations.

[0013] The control device 111 may obtain in advance information indicating which base station device's communication the relay station can relay. For example, in FIG. 1, the control device 111 may obtain in advance information indicating that the relay station 103 can relay the communication of the base station device 101 and the base station device 102. The control device 111 may obtain in advance information indicating which of a plurality of beams formed by each base station device the relay station can relay. For example, in FIG. 1, the control device 111 may obtain in advance information indicating that the relay station 103 can relay the communication of the beam with SSB ID=3 of the base station device 101 and the beam with SSB ID=1 of the base station device 102. The communication of which base station device (and beam) each relay station can relay can be specified by having the relay station measure the quality of the radio signal arriving from the surrounding base station device when the relay station is installed, and providing the measurement result to the control device 111 via, for example, the management device 112. For example, a combination of the PCI (and SSB ID) and the measurement result of the wireless quality is provided to the control device 111. Then, the control device 111 can specify a base station device that provides a cell of the PCI (or a beam corresponding to the SSB ID) associated with a wireless quality equal to or higher than a predetermined level as a candidate base station device to be relayed by the relay station.

[0014] The measurement of the radio quality of the relay station is performed in a state where a receiving beam is formed in the relay station. That is, the information in which the PCI (and SSB ID) and the radio quality are associated with each other is further associated with the identification information (beam ID) of the beam formed in the relay station. For example, when the relay station 103 uses a beam with beam ID=m (m is, for example, an integer), the relay station 103 receives a radio signal from the beam with SSB ID=3 of the base station device 101 with radio quality equal to or higher than a predetermined level, and the control device 111 is notified of beam ID=m, PCI=1, SSB ID=3, and information in which the radio quality is associated with each other. Similarly, when the relay station 103 uses a beam with beam ID=n (n is, for example, an integer), the relay station 103 receives a radio signal from the beam with SSB ID=1 of the base station device 102 with radio quality equal to or higher than a predetermined level, and the control device 111 is notified of beam ID=n, PCI=2, SSB ID=1, and information in which the radio quality is associated with each other. Thereafter, the control device 111 may notify the management device 112 that, for example, when the relay station 103 is to relay communication of the base station device 101, the relay station 103 should use a beam with a beam ID=m. Similarly, the control device 111 may notify the management device 112 that, for example, when the relay station 103 is to relay communication of the base station device 102, the relay station 103 should use a beam with a beam ID=n.

[0015] The management device 112 is connected to one or more relay stations, for example, by using a wired line, and manages relay communication such as switching of base station devices to be relayed at each relay station. For example, the management device 112 notifies the relay station 103 of a beam ID according to a control signal from the control device 111, thereby instructing a reception beam to be used and controlling the relay target by the relay station 103. In the above description, an example was described in which the control device 111 holds information indicating the relationship between the reception beam at the relay station and the base station device to be relayed, but this information may be held in the management device 112. In this case, the control device 111 manages only the PCI (and SSB ID) of the base station device that can be a relay target at each relay station, determines only which base station device (and beam) the relay station should relay communication of, and can notify the management device 112 of the result of the decision. This notification is performed, for example, by using the PCI (and SSB ID). The control device 111 manages the base station device (and beam) that is currently a relay target for each relay station, and also manages information on candidates for changing the relay target. Then, for example, when changing the relay target of the relay station, the control device 111 notifies the management device 112 of the PCI (and SSB ID). The management device 112 can manage each PCI (and SSB ID) in association with the beam ID of the reception beam of the corresponding relay station, and can notify the relay station to use the reception beam of the beam ID corresponding to the notified PCI (and SSB ID). In this way, the division of roles between the control device 111 and the management device 112 can be determined arbitrarily.

[0016] This network may be configured using an Open-Radio Access Network (O-RAN). For example, the control device 111 has a function as Service Management and Orchestration (SMO) of the O-RAN. The SMO includes a Non-Real Time RAN Intelligent Controller (Non-RT RIC). The base station device 101 and the base station device 102 may function as an O-RAN Distributed Unit (O-DU). The SMO (Non-RT RIC) collects various information from the O-DU using an O1 interface, and determines a policy for network control based on the collected information. In this embodiment, the SMO (Non-RT RIC) determines a policy for setting a base station device to be a relay target in the relay station, and transmits an instruction to the management device 112 functioning as an Element Management System (EMS) to control the relay station based on the policy.

[0017] In this embodiment, the control device 111 operates to appropriately set a base station device to be a relay target at the relay station based on the load (usage amount / usage rate of resource blocks, number of terminal devices connected simultaneously, etc.) in each base station device. For this process, the control device 111 acquires information from each base station device that can identify the load in that base station device. Here, each base station device can classify connected terminal devices into a first terminal device directly connected to the base station device and a second terminal device connected via a relay station, and notify the control device 111 of information that can identify the load due to the first terminal device and the load due to the second terminal device.

[0018] For example, a signal transmitted from a terminal device connected via a relay station is observed to be affected by a large propagation delay at the base station device due to relay processing by the relay station. As a result, the base station device sets a large timing advance value for the terminal device. Therefore, the base station device can identify a terminal device whose timing advance value is equal to or less than a predetermined value as a first terminal device, and identify a terminal device whose timing advance value exceeds the predetermined value as a second terminal device. Note that the predetermined value here can be, for example, the maximum value of the timing advance value set for the terminal device in each base station device while the relay station is not installed or the power supply of the relay station is off. That is, a terminal device whose timing advance value exceeds the maximum timing advance value when the relay station is not used can be determined to be a terminal device connected via a relay station. Note that the classification between the first terminal device and the second terminal device may be performed without using the timing advance value. As an example, a first time-frequency resource for random access used by a terminal device when directly connecting to a base station device may be different from a second time-frequency resource for random access used by a terminal device when connecting to a base station device via a relay station. In this case, the base station device may identify the terminal device connected via the first time-frequency resource as the first terminal device, and the terminal device connected via the second time-frequency resource as the second terminal device.

[0019] In this way, the base station device may identify the number of first terminal devices directly connected to the base station device itself and the number of second terminal devices connected via a relay station, and may notify the control device 111 of the identified numerical values. In the example of FIG. 1, the base station device 101 may identify that there are seven first terminal devices directly connected and three second terminal devices connected via a relay station 103, and may notify the control device 111 of the identified results. Similarly, the base station device 102 may notify the control device 111 that there are two first terminal devices directly connected and no second terminal device connected via a relay station. The base station device may also count the number of first terminal devices and second terminal devices connected for each beam, and notify the control device 111 of the number. That is, the base station device 101 may notify the control device 111 that there are three first terminal devices directly connected to the beam of SSB ID=1, three first terminal devices directly connected to the beam of SSB ID=2, one first terminal device directly connected to the beam of SSB ID=3, and three second terminal devices connected to the beam of SSB ID=3 via the relay station 103. Similarly, the base station device 102 may notify the control device 111 that there is one first terminal device directly connected to the beam of SSB ID=2, and one first terminal device directly connected to the beam of SSB ID=3.

[0020] Also, each base station device may notify the control device 111 of the usage amount and usage rate of the radio resources (frequency and time resources) by each of the first terminal device and the second terminal device. That is, the base station device may notify the control device 111 of the amount of radio resources allocated to each of the first terminal device directly connected and the second terminal device connected via a relay station, or the ratio of the amount of the allocated radio resources to the total amount of available radio resources. This amount of radio resources may be indicated by, for example, an accumulated value or an average value over a certain period of time. Also, the amount of radio resources may be an amount estimated according to the type of communication performed by each terminal device. That is, the amount of resources according to the amount of data communicated during a certain period in an application used by the terminal device may be specified as the amount of resources allocated to the terminal device. The base station device may notify the control device 111 of the result of summing up the amount of resources allocated to each of the terminal device in direct connection and the second terminal device in connection via a relay station.

[0021] Here, the information that the base station device 101 and the base station device 102 notify to the control device 111 will be described with reference to FIG. 2 and FIG. 3. In FIG. 2, UE1 to UE12 are identifiers assigned to the 12 terminal devices, respectively, and PCI indicates which base station device these terminal devices are connected to. Also, SSB ID indicates which beam formed by the base station device the terminal devices are communicating through. In the example of FIG. 2, it is shown that UE1 to UE3 are communicating through a beam with SSB ID=1 formed by the base station device 101. Similarly, UE4 to UE6 are communicating through a beam with SSB ID=2 formed by the base station device 101, and UE7 to UE10 are communicating through a beam with SSB ID=3 formed by the base station device 101. Here, it is assumed that the timing advance value of the base station device 101 while the relay station is not used is, for example, 15. In this case, it can be determined that UE7 is a first terminal device directly connected, and UE8 to UE10 are second terminal devices connected via a relay station. Therefore, the base station device 101 can notify the control device 111 that, for example, seven first terminal devices and three second terminal devices exist. The base station device 101 may also notify the control device 111 that three first terminal devices are connected to a beam with SSB ID=1, three first terminal devices are connected to a beam with SSB ID=2, and one first terminal device and three second terminal devices are connected to a beam with SSB ID=3. Similarly, the base station device 102 can notify the control device 111 that two first terminal devices (UE11 and UE12) exist under its own device, or that one first terminal device is connected to a beam with SSB ID=2 and one first terminal device is connected to a beam with SSB ID=3.

[0022] Also, the base station device 101 and the base station device 102 may add up the amount of resources used in each beam and notify it, for example, as shown in FIG. 3. For example, as shown in FIG. 2, the downlink resource usage rates (ratios (%) of the number of allocated RBs to all resource blocks (RBs)) by UE1 to UE3 are 5, 5, and 10, respectively. In this case, the base station device 101 may add up these and determine the resource usage rate of the first terminal device in the uplink in the beam with SSB ID=1 as 20%. Similarly, the base station device 101 may determine the resource usage rate of the first terminal device in the downlink in the beam with SSB ID=1 as 15%. Also, the base station device 101 may determine the resource usage rates of the first terminal device (UE7) in the downlink and uplink in the beam with SSB ID=3 as 5% and 3%, respectively, and the resource usage rates of the second terminal device (UE8 to UE10) in the downlink and uplink in the beam with SSB ID=3 as 10% and 9%, respectively. FIG. 3 shows the result of such identification based on the information as shown in FIG. 2. In addition, in the "terminal device type" in FIG. 3, "0" represents the first terminal device, and "1" represents the second terminal device. The base station device can notify the control device 111 of the information as shown in FIG. 3. In addition, all of the information in FIG. 3 does not need to be notified to the control device 111. That is, for example, only the number of the first terminal device and the second terminal device connected to each beam, which is indicated by the "number of simultaneously connected UEs", may be notified, or only the resource usage rate may be notified. In addition, for example, only the higher value of the resource usage rates of the downlink and uplink may be notified to the control device 111. In addition, the example of FIG. 3 shows information for each beam, but information for each cell (PCI) may be notified to the control device 111. In addition, in the above example, an example is shown in which information on the resource usage rate is notified to the control device 111, but the amount of resources (for example, the number of RBs) may be notified to the control device 111.

[0023] In the above example, the base station device identifies the first terminal device and the second terminal device, and notifies the control device 111 of the result of counting the number of each terminal device, but this is not limited to the above. For example, the base station device may notify the control device 111 of information that enables classification of the first terminal device and the second terminal device, such as information on the connected terminal device and its timing advance value. In one example, the base station device may notify the control device 111 of a list of the timing advance values ​​of each of the connected communication devices. The control device 111 may identify the number of first terminal devices and the number of second terminal devices based on the timing advance value for each of the terminal devices connected to each base station device. In addition, the base station device may notify the control device 111 of flag information indicating whether each of the connected terminal devices is a first terminal device or a second terminal device. That is, a flag indicating whether each of the connected terminal devices is a first terminal device or a second terminal device may be set for each of the multiple terminal devices, and the flag information may be notified to the control device 111. The control device 111 can identify the number of first terminal devices and second terminal devices connected to each base station device based on the information of the flag set in each terminal device. Also, each base station device may notify the control device 111 of the resource usage rate and the amount of used resources in each terminal device. That is, each base station device may notify the control device 111 of the information shown in Fig. 2 regarding the terminal devices connected to the base station device without processing it into the information shown in Fig. 3.

[0024] The control device 111 determines the relay target of the relay station 103 based on the notified information. For example, the control device 111 determines whether or not to change the relay target of the relay station 103 so as to correct the imbalance in the number of terminal devices simultaneously connected to each base station device. For example, in the state of FIG. 1, the number of terminal devices connected to the base station device 101 is 10, while the number of terminal devices connected to the base station device 102 is 2, and there is a large difference in the number of simultaneous connections. Therefore, by setting the base station device 102 as the relay target of the relay station 103, the number of terminal devices connected to the base station device 101 becomes 7, and the number of terminal devices connected to the base station device 102 becomes 5. Therefore, for example, the control device 111 can determine whether or not to change the base station device that is the relay target of the relay station 103 depending on whether the number of simultaneous connections of terminal devices in the base station device currently being the relay target exceeds a predetermined number. In addition, the control device 111 determines, for example, whether or not there is a base station device that can perform relay by the relay station and is not currently being the relay target, and the current number of simultaneous connections is equal to or less than a predetermined number. If such a base station device exists, the control device 111 decides to change the relay target of the relay station to that base station device. Note that, when making this determination, the control device 111 may focus only on the number of first terminal devices directly connected. That is, by comparing the number of terminal devices directly connected at the same time, excluding the influence of the second terminal device communicating via the relay station, and relaying the communication of the base station device with a smaller number to the relay station, it is possible to suppress the bias in the number of connected terminal devices. For example, focusing on the first terminal devices, seven first terminal devices are connected to the base station device 101, while two first terminal devices are connected to the base station device 102. Here, if the predetermined value is 5, the number of simultaneous connections of the first terminal devices of the base station device 101 exceeds the predetermined value, and the number of simultaneous connections of the first terminal devices of the base station device 102 is equal to or less than the predetermined value. Therefore, the control device 111 may determine that the relay target of the relay station 103 should be the base station device 102.

[0025] The control device 111 may also determine whether to change the base station device to be relayed depending on whether at least one of the number of terminal devices connected via a relay station, the resource usage rate, and the resource usage rate exceeds a predetermined reference value. For example, when there are many terminal devices connected to a base station device via a specific relay station, or when the terminal devices use a large amount of resources in ongoing communication, a change in the relay target by the specific relay station may cause communication interruption or an increase in signaling overhead due to processing such as handover. For this reason, the control device 111 may determine not to change the base station device to be relayed when at least one of the number of terminal devices connected to the base station device via the relay station to be controlled, the resource usage rate by the terminal devices, and the resource usage rate in use by the terminal devices exceed a predetermined reference value. The control device 111 may also determine to change the base station device to be relayed when all of the number of terminal devices connected to the base station device via the relay station to be controlled, the resource usage rate by the terminal devices, and the resource usage rate in use by the terminal devices are equal to or less than a predetermined reference value. In addition, the control device 111 may decide to change the base station device to be relayed when at least one of the number of terminal devices connected to the base station device via the relay station to be controlled, the amount of resources used by the terminal devices, and the usage rate of the resources being used by the terminal devices is below a predetermined value.

[0026] In addition, the control device 111 may determine to change the base station device to be relayed when the resource usage rate or usage amount by the first terminal device in at least one of the downlink and the uplink of the base station device currently being relayed exceeds a predetermined value. That is, when the load of the terminal device directly connected to the current base station device to be relayed is high, it is assumed that the base station device is in a high-load state due to the additional load due to relaying on the base station device. Therefore, the control device 111 may determine to change the base station device to be relayed in order to remove the base station device from the relay target in order to reduce the load of such a base station device. Note that the predetermined value used for this determination may be different for the downlink and the uplink.

[0027] Furthermore, the control device 111 may determine whether or not there is a base station device that is not currently a relay target, in which the resource usage rate or usage amount by the first terminal device in at least one of the downlink and the uplink does not exceed a predetermined value. Then, the control device 111 may decide to change the relay target base station device on the condition that such a base station device exists. That is, even if the load of the terminal device directly connected to the current relay target base station device is high, if the load of other base station devices is also high, it is not necessary to change the relay target base station device. Note that the predetermined value used for this determination may also be different between the downlink and the uplink.

[0028] The control device 111 may use only one of the above-mentioned determinations of whether or not to determine the base station device to be relayed, or may use a combination of two or more. That is, it may be determined whether or not to change the base station device to be relayed according to only one of the above-mentioned examples, or two or more may be combined, and the base station device to be relayed may not be changed unless it is determined in any of the determinations that the base station device to be relayed should be changed. In addition, in the above-mentioned example, control based on the load is performed in units of base station devices, but control may be performed in units of beams.

[0029] In the example of Figure 1, only a small number of base station devices and repeaters are shown, but it should be understood that a large number of base station devices may be deployed, one repeater may be capable of relaying three or more base station devices, and a large number of repeaters may also be deployed.

[0030] (Device configuration) Next, a configuration example of the control device and base station device as described above will be described. FIG. 4 is a diagram showing a hardware configuration example of the control device and base station device. In one example, the control device and base station device are configured to include a processor 401, a ROM 402, a RAM 403, a storage device 404, and a communication circuit 405. The processor 401 is a computer configured to include one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the control device and base station device and each processing described later by reading and executing a program stored in the ROM 402 or the storage device 404. The ROM 402 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the control device and base station device. The RAM 403 functions as a workspace when the processor 401 executes a program, and is a random access memory that stores temporary information. The storage device 404 is, for example, a removable external storage device. The communication circuit 405 is a communication circuit for communicating with other devices. The control device includes, for example, a communication circuit 405 for connecting and communicating with each base station device, and a communication circuit 405 for connecting and communicating with a management device that manages the relay station. The base station device also includes, for example, a communication circuit 405 for wired communication with the control device, and a communication circuit 405 for wireless communication with the terminal device.

[0031] FIG. 5 is a diagram showing an example of the functional configuration of a base station device. The base station device includes, as its functional configuration, a UE information collecting unit 501, a UE classifying unit 502, and an information notifying unit 503. These functions can be realized, for example, by the processor 401 executing a program stored in the ROM 402 or the storage device 404. However, this is only an example, and these functions may be realized by dedicated hardware or a processing circuit in the communication circuit 405. Note that FIG. 5 shows only functions related to this embodiment, and the base station device naturally has functions (not shown) that a normal base station device in a cellular communication system has. In addition, when the wireless communication system is configured using O-RAN, the base station device also has a function as an O-DU.

[0032] The UE information collecting unit 501 collects information on terminal devices connected to the base station device itself. The UE information collecting unit 501 collects information on the number of terminal devices currently connected and the amount of at least one of the downlink and uplink resources allocated to each of the terminal devices. The UE information collecting unit 501 may also obtain information on the timing advance value of each terminal device as necessary. The UE classifying unit 502 classifies each terminal device connected to the base station device itself as either a first terminal device directly connected to the base station device or a second terminal device connected via a relay station. For example, the UE classifying unit 502 classifies a terminal device whose timing advance value is equal to or less than a predetermined value as a first terminal device, and classifies a terminal device whose timing advance value exceeds the predetermined value as a second terminal device. For example, the UE classifying unit 502 may determine that the terminal device is a second terminal device connected via a relay station when the frequency / time resource used in the random access procedure when the terminal device connects is a resource for the relay station. The UE classification unit 502 may determine whether the terminal device is a first terminal device or a second terminal device by a procedure other than these. In addition, such UE classification may be performed in the control device, and in that case, the UE classification unit 502 may be provided in the control device, not in the base station device. The information notification unit 503 notifies the control device of information capable of identifying the load due to the first terminal device and the load due to the second terminal device based on the information collected in the UE information collection unit 501. For example, the information notification unit 503 may transmit information collected in the UE information collection unit 501 as shown in FIG. 2 to the control device as it is, or may transmit information aggregated as shown in FIG. 3 to the control device. In addition, when the base station device is an O-DU, the information notification unit 503 notifies the control device functioning as an SMO of information using the O1 interface.

[0033] Fig. 6 is a diagram showing an example of the functional configuration of the control device. The control device is configured to include, as its functional configuration, an information acquisition unit 601, a relay target determination unit 602, and a relay station control notification unit 603. These functions can be realized, for example, by the processor 401 executing a program stored in the ROM 402 or the storage device 404. However, this is only an example, and these functions may be realized by dedicated hardware. Note that Fig. 6 shows only functions related to this embodiment, and for example, when the wireless communication system is configured using O-RAN, the control device naturally has a function as an SMO.

[0034] The information acquisition unit 601 receives information for use in controlling the relay station from each base station device. For example, as shown in FIG. 3, the information acquisition unit 601 may receive information from each base station device that can identify the load caused by a first terminal device directly connected to each base station device and the load caused by a second terminal device connected to each base station device via a relay station. The load here may be, for example, the number of terminal devices, the amount of resource usage, and the resource usage rate. The amount of resource usage and the usage rate may be expressed as the amount of resource block usage and the usage rate. Although information per beam is shown in FIG. 3, information per base station device may be notified to the control device. Also, the information acquisition unit 601 may receive individual information of the terminal devices connected to the base station device as shown in FIG. 2. In this case, the information acquisition unit 601 has, for example, the same function as the above-mentioned UE classification unit 502 (not shown), and classifies each terminal device included in the received information into a first terminal device and a second terminal device. Then, the information acquisition unit 601 may acquire information that specifies the load due to the first terminal device and the load due to the second terminal device connected to each base station device via a relay station based on the classification result. The relay target determination unit 602 may determine the base station device to be relayed by the relay station based on the information acquired by the information acquisition unit 601. As described above, this determination process is performed so that the load is distributed based on the number of first terminal devices in each base station device, the amount of resources used by the first terminal devices, the number of second terminal devices, the amount of resources used by the second terminal devices, and the like. Note that the relay target determination unit 602 recognizes in advance candidates for base station devices that can be relayed by the relay station, and selects a base station device to be relayed by the relay station from among the candidates. For example, when a relay station is newly installed, the relay target determination unit 602 may collect measurement results of the wireless quality of wireless signals sent from surrounding base station devices at the relay station, and may specify the base station device to be a candidate for the relay target based on the results. The relay target candidates may be specified under the control of a management device, and the specified result may be notified from the management device to the control device. The relay target determination unit 602 may repeatedly execute the above-mentioned determination process at regular intervals.When it is determined in the determination process by the relay target determination unit 602 that the base station device to be relayed at the relay station is to be changed, the relay station control notification unit 603 transmits an instruction to the management device to direct the direction of the reception beam of the relay station to the base station device to be the relay target after the change. In response to receiving this instruction, the management device controls the relay station to direct the direction of the reception beam of the relay station to the direction of the base station device to be the relay target after the change.

[0035] (Processing flow) Next, an example of the flow of processing executed in a wireless communication system will be described with reference to Fig. 7. The example of Fig. 7 shows an example of processing executed in a configuration as shown in Fig. 1. That is, it is assumed that the base station device 102 initially communicates only with a first terminal device (UE) directly connected thereto (S701, S702), and the base station device 101 communicates with the first terminal device directly connected thereto (S704 to S706) as well as with a second terminal device connected via a relay station 103 (S707). Here, it is assumed that the number of first terminal devices directly connected to the base station device 101 is greater than the number of first terminal devices directly connected to the base station device 102, and the load on the base station device 101 is increased by the second terminal device connected to the base station device 101 via the relay station 103.

[0036] Each base station device acquires information that can identify the load caused by the connected terminal device (S703, S708). This information may be only information that can identify whether each terminal device is a first terminal device or a second terminal device, such as a timing advance value in each terminal device or information on resources used during random access, or may include information on the amount of resources (usage amount / usage rate) allocated to each terminal device. Then, each base station device aggregates, for example, the number of first terminal devices and the number of second terminal devices, and information on the amount and rate of resource usage by each of the first terminal device and the second terminal device, and notifies the control device 111 (S709, S710). This notification is performed, for example, using the O1 interface. Note that each base station device may notify the control device 111 of the information collected about each terminal device as it is, without aggregating the information. In this case, however, information including at least information for identifying whether each terminal device is a first terminal device or a second terminal device is notified to the control device 111, and the control device 111 determines whether each terminal device is a first terminal device or a second terminal device. As a result, in either case, the control device 111 obtains information for identifying the load caused by the first terminal device and the load caused by the second terminal device.

[0037] The control device 111 determines the base station device to be the relay target based on the information notified from each base station device (S711). Here, it is assumed that the control device 111 determines that the base station device 101 currently set as the relay target is in a high load state, and decides to change the relay target to the base station device 102. In this case, the control device 111 notifies the management device 112 of information on the changed relay target (e.g., the PCI of the cell formed by the base station device 102) in order to change the relay target of the relay station 103 (S712). Then, the management device 112 transmits an instruction to change the relay target to the relay station 103 (S713), and the relay station 103 changes the relay target according to this instruction (S714). For example, the management device 112 notifies the relay station 103 of a beam ID for identifying the reception beam to be set, and the relay station 103 uses the reception beam corresponding to the beam ID, thereby changing the relay target.

[0038] Then, when the base station device to be relayed is changed from the base station device 101 to the base station device 102 in the relay station 103, communication is performed according to the changed settings (S715 to S720). Note that, for example, the second terminal device, which is communicating using the relay station 103, will perform processing such as handover due to the change in the base station device to be relayed. For this reason, for example, the control device 111 may transmit an instruction to the base station device 101 to have the second terminal device perform handover to the base station device 102 in parallel with instructing the management device 112 to change the relay target by the relay station 103. For example, the control device 111 may adjust the timing of the change in the relay target by the relay station 103 and the handover processing led by the base station device 101 so that the second terminal device can transmit a random access preamble to the base station device 102 via the relay station 103 immediately after the change in the relay target by the relay station 103. By such processing, it is possible to shorten the period during which the communication of the second terminal device is interrupted.

[0039] Next, an example of the flow of the relay target determination process executed by the control device 111 in S711 will be described with reference to Fig. 8. Note that this process is only an example, and in particular, only a part of the several determination processes described below may be performed, or additional conditions may be added. Also, the order of the processes may be freely changed within the scope that does not change the purpose of the processes.

[0040] The control device 111 judges whether the number of second terminal devices connected to the base station device via the relay station or the resource usage by the second terminal device exceeds a reference value (S801). Here, for convenience, the term "reference value" is used as a criterion for condition judgment regarding the number of second terminal devices and the resource usage by the second terminal device, but the reference value when the number of second terminal devices is used for judgment and the reference value when the resource usage by the second terminal device is used for judgment are naturally different values. Also, in this judgment, an example is described in which either the number of second terminal devices or the resource usage by the second terminal device is used for judgment, but it may be judged whether both are satisfied. Also, instead of the resource usage, the resource usage rate may be used for judgment. When the number of second terminal devices or the resource usage by the second terminal device exceeds the reference value (YES in S801), the control device 111 ends the process without changing the base station device to be relayed by the relay station. This is because, when the number of second terminal devices is greater than a predetermined number or the resource usage by the second terminal devices exceeds a predetermined amount, changing the base station device to be relayed by the relay station is expected to have a large effect on the communication of the second terminal devices. That is, when the number of second terminal devices is large, the signaling overhead such as handover due to the change of the relay target increases, and the communication performance may deteriorate. Also, when the resource usage by the second terminal devices is large, the disconnection of communication due to handover may greatly deteriorate the communication quality. For this reason, the control device 111 may decide not to change the base station device to be relayed by the relay station in such a situation.

[0041] If both the number of second terminal devices and the resource usage by the second terminal devices do not exceed the reference value (NO in S801), the control device 111 subsequently judges whether the resource usage in the current relay target exceeds a predetermined value (S802). This judgment may be performed using the sum of the resource usage by the first terminal device and the resource usage by the second terminal device, or only the resource usage by the first terminal device may be the subject of the judgment. Here, it is judged whether the base station device of the current relay target is in a high load state. If the resource usage in the current relay target does not exceed a predetermined value (NO in S802), it is not in a high load state, so the control device 111 ends the process without changing the base station device of the relay target. Note that this judgment may be performed separately for the resource usage of the downlink and the resource usage of the uplink, and if the resource usage in both does not exceed the predetermined value, it may be judged not to change the base station device of the relay target. That is, when either the downlink resource usage or the uplink resource usage exceeds a predetermined value, it may be determined that the resource usage in the current relay target base station device exceeds the predetermined value (YES in S802).

[0042] When the control device 111 determines that the resource usage in the current relay target base station device exceeds a predetermined value (YES in S802), it then determines whether or not the number of first terminal devices directly connected to the current relay target base station device exceeds a predetermined number (S803). When the number of first terminal devices directly connected to the current relay target base station device does not exceed a predetermined number (NO in S803), the control device 111 ends the process without changing the relay target base station device. When the number of first terminal devices directly connected to the current relay target base station device is so large that it exceeds a predetermined number (YES in S803), the control device 111 determines that the base station device is in a high load state, and proceeds to the process in S804. Note that the process in FIG. 8 is a process in which it is determined that the base station device is in a high load state when the resource usage in the current relay target base station device exceeds a predetermined value and the number of first terminal devices directly connected to the base station device exceeds a predetermined number, but it may be determined that the base station device is in a high load state by only one of these determinations. In other words, a base station device may be determined to be in a high-load state if the resource usage by a first terminal device exceeds a predetermined value even if there are only a few first terminal devices directly connected to the current relay target base station device, or if the number of first terminal devices exceeds a predetermined number even if the resource usage by the first terminal device at the current relay target base station device does not exceed a predetermined value.

[0043] In S804, the control device 111 judges whether there is a base station device that is a candidate for a relay target and is not a current relay target, and whose resource usage does not exceed a predetermined value. This judgment can be performed in the same manner as S802. Then, when such a base station device that is a candidate for a relay target exists (YES in S804), the control device 111 judges whether the number of first terminal devices directly connected to the base station device exceeds a predetermined number (S805). That is, the control device 111 judges whether there is a base station device that is a candidate for a relay target in a relatively low load state. Then, when such a base station device does not exist (NO in S804 or NO in S805), the control device 111 decides not to change the relay target and ends the process. That is, when the relay target is changed to a base station device in a high load state, the change process of the relay target from that base station device is simply executed again, so such a change can be prevented. On the other hand, when a base station device in a low load state exists (YES in S805), the control device 111 decides to change the base station device as the relay target to the base station device in the low load state (S806). The determination of whether or not there is a base station device in a low load state may be performed by only one of the determinations in S804 and S805. That is, when there are many first terminal devices directly connected to a base station device that is a candidate for relaying, but the resource usage by the first terminal devices does not exceed a predetermined value, or when the resource usage by the first terminal devices in the base station device that is a candidate for relaying exceeds a predetermined value but the number of first terminal devices does not exceed a predetermined number, the base station device may be determined to be in a low load state.

[0044] In this embodiment, as described above, by appropriately setting the base station device to be relayed by the relay station, it is possible to distribute the load between the base station devices and improve the efficiency of communication. Therefore, it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0045] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. an acquisition means for acquiring information capable of identifying a load caused by a first terminal device directly connected to each of the plurality of base station devices and a load caused by a second terminal device connected via a relay station to each of the plurality of base station devices whose communication is relayed by the relay station; a determination means for determining whether to change a base station device that is a relay target of communication of the relay station based on the information for each of the plurality of base station devices; a control means for controlling, when it is determined that a base station device for relaying communication by the relay station is to be changed, to direct a beam of the relay station in a direction toward the changed base station device; A control device comprising:

2. The control device is a device having a function of Service Management and Orchestration (SMO) of an Open-Radio Access Network (O-RAN), Each of the plurality of base station devices is an apparatus having a function of a Distributed Unit (DU) of the O-RAN, The information is notified from the plurality of base station devices to the control device using an O1 interface of the O-RAN. The control device according to claim 1 .

3. The control device according to claim 2, characterized in that the control means notifies a management device that manages the relay station of information indicating the changed base station device, and causes the management device to transmit an instruction to the relay station to direct the beam of the relay station in the direction of the changed base station device.

4. The control device according to claim 1 , characterized in that the information for each of the plurality of base station devices includes information indicating the number of the first terminal devices and the number of the second terminal devices for each of the plurality of base station devices.

5. The control device according to claim 1, characterized in that the information for each of the plurality of base station devices includes information indicating, for each of the plurality of base station devices, a usage rate of at least one of an uplink resource block and a downlink resource used by each of the first terminal device and the second terminal device.

6. The control device according to claim 1, characterized in that the information for each of the plurality of base station devices includes information indicating, for each of the plurality of base station devices, a usage amount of at least one of uplink resource blocks and downlink resources used by each of the first terminal device and the second terminal device.

7. the acquiring means acquires, for each of the plurality of base station devices, a timing advance value for each terminal device connected to the respective plurality of base station devices; the acquiring means, for each of the plurality of base station devices, identifies a terminal device whose timing advance value is equal to or less than a predetermined value as a first terminal device, and identifies the number of the first terminal devices as information on the load caused by the first terminal devices, and identifies a terminal device whose timing advance value is greater than a predetermined value as a second terminal device, and identifies the number of the second terminal devices as information on the load caused by the second terminal devices. The control device according to claim 1 .

8. the acquiring means acquires, for each of the plurality of base station devices, a timing advance value for each terminal device connected to the respective plurality of base station devices and a value indicating a load for each terminal device; the acquiring means, for each of the plurality of base station devices, identifies a terminal device whose timing advance value is equal to or less than a predetermined value as the first terminal device, and identifies a sum of load values ​​of the first terminal device as information on the load of the first terminal device, and identifies a terminal device whose timing advance value is greater than the predetermined value as the second terminal device, and identifies a sum of load values ​​of the second terminal device as information on the load of the second terminal device. The control device according to claim 1 .

9. A base station device having a function of a Distributed Unit (DU) of an Open-Radio Access Network (O-RAN), A base station device characterized by having a notification means for notifying a control device having a Service Management and Orchestration (SMO) function of the O-RAN of information capable of identifying a load due to a first terminal device directly connected to the base station device and a load due to a second terminal device connected via a relay station when communication of the base station device is relayed by the relay station, using an O1 interface of the O-RAN.

10. An acquisition means for acquiring a timing advance value for each terminal device connected to the base station device; a determination means for determining the number of the first terminal devices as information on the load caused by the first terminal devices, when the terminal devices have a timing advance value equal to or less than a predetermined value, and for determining the number of the second terminal devices as information on the load caused by the second terminal devices, when the terminal devices have a timing advance value greater than the predetermined value, and and The notifying means notifies the control device of the number of the first terminal devices and the number of the second terminal devices as information on a load caused by the first terminal devices and a load caused by the second terminal devices. The base station device according to claim 9 .

11. An acquisition means for acquiring a timing advance value for each terminal device connected to the base station device and a value indicating a load for each terminal device; a determination means for determining a terminal device whose timing advance value is equal to or less than a predetermined value as the first terminal device, determining a value obtained by adding up load values ​​of the first terminal device as information on the load of the first terminal device, and determining a terminal device whose timing advance value is greater than the predetermined value as the second terminal device, determining a value obtained by adding up load values ​​of the second terminal device as information on the load of the second terminal device; and The notifying means notifies the control device of information on the load caused by the first terminal device and the load caused by the second terminal device identified by the identifying means. The base station device according to claim 9 .

12. A control method executed by a control device, comprising: acquiring information from a plurality of base station devices that can identify a load caused by a first terminal device directly connected to each of the plurality of base station devices and a load caused by a second terminal device connected via a relay station to each of the plurality of base station devices whose communication is relayed by the relay station; determining whether to change a base station device that is a relay target of communication of the relay station based on the information about each of the plurality of base station devices; When it is determined that the base station device for relaying communication by the relay station is to be changed, control is performed to direct the beam of the relay station in the direction of the changed base station device; A control method comprising:

13. A communication method executed by a base station device having a function of a Distributed Unit (DU) of an Open-Radio Access Network (O-RAN), comprising: The method includes notifying a control device having a function of SMO (Service Management and Orchestration) of the O-RAN of information capable of identifying a load caused by a first terminal device directly connected to the base station device and a load caused by a second terminal device connected via a relay station when communication of the base station device is relayed by the relay station, using an O1 interface of the O-RAN. A communication method comprising:

14. A computer provided in the control device acquiring information from a plurality of base station devices that can identify a load caused by a first terminal device directly connected to each of the plurality of base station devices and a load caused by a second terminal device connected via a relay station to each of the plurality of base station devices, communication of which is relayed by a relay station; determining whether to change a base station device that is a relay target of communication of the relay station based on the information for each of the plurality of base station devices; When it is determined that the base station device to which the relay station relays communication is to be changed, control is performed to direct the beam of the relay station in the direction of the changed base station device. Program for.

15. A computer provided in a base station device having a function of a Distributed Unit (DU) of an Open-Radio Access Network (O-RAN), A control device having a function of SMO (Service Management and Orchestration) of the O-RAN is notified of information capable of identifying a load caused by a first terminal device directly connected to the base station device and a load caused by a second terminal device connected via a relay station when communication of the base station device is relayed by the relay station, using an O1 interface of the O-RAN; Program for.

Images