Wireless communication system, control device, destination position determining method, and program

Abstract

This wireless communication system comprises: one or more movable wireless station devices which wirelessly communicate with one or more terminal devices; and a control device. The control device: calculates, on the basis of the positions of the terminal devices, a plurality of movement destination position candidates of the respective movable wireless station devices at which a required quality of communication with the terminal devices is satisfied; and selects, from among the plurality of movement destination position candidates, a movement destination position candidate at which the sum of movement costs for the movable wireless station devices to move from a home position to the movement destination becomes minimum, or a movement destination position candidate at which the maximum value of movement cost among the one or more movable wireless station devices to move from the home position to the movement destination becomes minimum, as a movement destination position for the movement control.

Description

[Technical Field]

[0001] The present invention relates to a technique for controlling the movement of mobile radio station devices such as mobile base station devices. [Background technology]

[0002] Wireless communication technologies such as 5G and wireless LAN are becoming widespread. In recent years, a technology has been studied to provide a natural communication environment in which users are not aware of the wireless network by moving base station devices according to the degree of congestion of terminal devices and changes in the spatial environment (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Institute of Electronics, Information and Communication Engineers 2021 General Conference B-5-131 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, by moving the base station device, it is possible to effectively utilize radio resources and provide an appropriate radio communication service to the terminal device.

[0005] However, if the distance (or time) required to move the base station device is long, there is a possibility that the communication quality of the terminal device will deteriorate during the movement. In addition, the power consumption required for the movement will increase. Note that the object to be moved is not limited to a base station device. For example, the object to be moved may be a relay station device, an AP (access point), etc. The object to be moved will be collectively referred to as a "mobile radio station device."

[0006] The present invention has been made in view of the above points, and aims to provide a technology for suppressing deterioration in communication quality during movement and suppressing an increase in power consumption due to movement when performing mobility control on a mobile radio station device. [Means for solving the problem]

[0007] According to the disclosed technology, a communication device that communicates with one or more terminal devices multiple A wireless communication system comprising a mobile radio station device and a control device, The control device calculating a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device based on the location of each terminal device; Among multiple destination location candidates, the travel cost required to move from the home position to the destination is multiple The destination location candidate with the smallest maximum value among the mobile radio station devices is selected as the destination location for the movement control. A wireless communication system is provided. [Effects of the Invention]

[0008] According to the disclosed technique, when performing mobility control on a mobile radio station device, it is possible to suppress deterioration in communication quality while the device is moving, and also to suppress an increase in power consumption due to movement. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the overall configuration of a system. [Figure 2] 10 is a diagram for explaining an outline of the operation of determining a destination position by the control device 30. FIG. [Figure 3] FIG. 1 is a diagram illustrating an example of an apparatus configuration. [Figure 4] 4 is a flowchart illustrating the operation of the control device 30. [Figure 5] FIG. 1 illustrates hierarchical clustering. [Figure 6] FIG. 2 illustrates an example of a hardware configuration of the apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention (the present embodiment) will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0011] In the following description of the embodiment, a mobile base station device is used as the mobile radio station device to be moved, but this is just an example. The base station device mentioned below may be replaced with a relay station device, an AP, or any other mobile radio station device.

[0012] Furthermore, the base station device may be a base station device in a cellular communication network (e.g., 3G, 4G / LTE, 5G, 6G), a base station device in a wireless LAN, or a base station device in a communication system other than these. Note that, hereinafter, the base station device may be referred to as "BS."

[0013] (Example of overall system configuration) An example of the overall configuration of a system according to this embodiment is shown in Fig. 1. As shown in Fig. 1, this system includes a plurality of base station devices 10 and a plurality of terminal devices 20. There is also a control device 30 that controls the mobility of the base station devices 10. A system consisting of one or more base station devices 10 and the control device 30 may be called a wireless communication system.

[0014] Each base station device 10 can move based on control from the control device 30. The base station device 10 may be called a mobile base station device. Any means for movement may be used. For example, the movement may be achieved by mounting the base station device 10 on a drone, or by mounting the base station device 10 on rails so that the base station device 10 can move on the rails, or by mounting the base station device 10 on a vehicle, or by other means. Here, the "base station device 10" is also intended to include a means for movement (drive unit).

[0015] Furthermore, if the direction of the antenna provided in the base station device 10 is variable, the control device 30 can also change the direction of the antenna provided in the base station device 10.

[0016] Each base station device 10 can communicate wirelessly with a terminal device 20. Furthermore, each base station device 10 can communicate with a control device 30 via wire or wirelessly. A terminal device 20 can communicate wirelessly with one or more base station devices 10.

[0017] (Outline of operation of determining destination position by control device 30) As described above, if the distance (or time) required to move the base station device 10 is long, there is a possibility that the communication quality of the terminal device 20 will deteriorate during the movement. In addition, the power consumption required for the movement will increase.

[0018] Therefore, in this embodiment, the control device 30 determines the destination location of the base station device 10 in consideration of the movement cost of the base station device 10. An outline of a method for determining the destination location will be described with reference to Fig. 2.

[0019] First, the control device 30 acquires the position of each terminal device 20. In this embodiment, it is assumed that the terminal position cannot be predicted (or is difficult), and the position of each terminal device 20 here is the current position. However, if it is a short time in the future, and the future position of the terminal can be predicted, the position of each terminal device 20 here may be a future position. In this embodiment, a destination position of the base station device 10 suitable for the position of each terminal device 20 acquired here is determined.

[0020] The control device 30 calculates destination position candidates for each base station device 10 based on the acquired positions of each terminal device 20. The calculation method will be described in detail later.

[0021] In this embodiment, each base station device 10 has a predetermined position (called a home position).

[0022] An example is shown in Fig. 2. In the example of Fig. 2, the control device 30 calculates a destination location candidate where the route from the home position to the destination is route 1, and a destination location candidate where the route from the home position to the destination is route 2. Of these two destination location candidates, the control device 30 selects the destination location candidate of route 1, which has the lowest travel cost from the home position to the destination, and executes movement of each base station device 10 using the destination location of route 1.

[0023] It should be noted that the origin position is not necessarily the home position when each base station device 10 moves. In other words, in this embodiment, for the next movement of a base station device 10 located at a certain position, the destination position is determined using the travel cost from the home position to the destination.

[0024] (Device configuration example) Fig. 3 shows an example of the configuration of devices that make up a wireless communication system according to this embodiment. As shown in Fig. 3, this wireless communication system has a control device 30 and a base station device 10. As mentioned above, the base station device 10 is an example of a mobile wireless station device that is subject to mobility control. Although Fig. 3 shows one base station device 10, in reality there are one or more base station devices 10.

[0025] The control device 30 and the base station device 10 are connected by wire or wirelessly. As shown in FIG.

[0026] The base station device 10 includes a driving unit 11. The driving unit 11 moves the base station device 10 to a desired position in response to an instruction from the control unit 34 of the control device 30.

[0027] The control device 30 includes a terminal position acquisition unit 31, a destination candidate calculation unit 32, a destination position determination unit 33, and a control unit 34. In the example of Fig. 3, an environment recognition unit 35 (camera, sensor, etc.) is provided outside the control device 30.

[0028] The terminal position acquisition unit 31 acquires the position of each terminal device 20. For example, the terminal position acquisition unit 31 acquires the position of each terminal device 20 from information indicating the location of each terminal device 20 acquired by the environment recognition unit 35.

[0029] The destination candidate calculation unit 32 calculates destination position candidates for the base station device 10 based on the positions of the terminal devices 20 acquired by the terminal position acquisition unit 31. The destination position determination unit 33 determines a destination position to be used for actual movement control from the multiple destination position candidates.

[0030] The control unit 34 executes control to move each base station device 10 to the destination position of each base station device 10 determined by the destination position determination unit 33. The control unit 34 may be provided outside the control device 30.

[0031] (Example of operation) Next, the operation of the control device 30 will be described in accordance with the procedure of the flowchart in Fig. 4. In the operation described below, it is assumed that there is an area (called a target area) that the control device 30 is responsible for, and that the terminal devices 20 and base station devices 10 within this target area are the control targets. Furthermore, one or more terminal devices 20 and one or more base station devices 10 exist within the target area. Furthermore, there is a home position for each base station device 10. The home position may be located within the target area or outside the target area.

[0032] <s101> In S101, the terminal position acquisition unit 31 acquires the position of each terminal device 20.

[0033] <s102> In S102, the destination candidate calculation unit 32 calculates a plurality of destination position candidates for each base station device 10 based on the position of the terminal obtained by the terminal position acquisition unit 31. The method of calculating the destination position candidates for each base station device 10 is not limited to a specific method, but for example, the following calculation method example 1 or calculation method example 2 can be used.

[0034] Note that the following calculation method examples 1 and 2 assume that the antenna of the base station device 10 is an omnidirectional antenna. If the antenna of the base station device 10 is a directional antenna (an antenna whose direction can be changed), for example, in the calculation of the predicted communication quality below, the predicted communication quality may be calculated when the antenna is pointed in the direction that provides the best predicted communication quality.

[0035] Calculation method example 1: The destination candidate calculation unit 32 first randomly changes the terminal clustering initial value for multiple terminal devices 20 in the target area and performs terminal clustering using the k-means method. Specifically, for example, the initial terminal clustering value is set to the number (M) of target base station devices 10, and the multiple terminal devices 20 are divided into M clusters. This type of clustering is performed multiple times with the initial terminal clustering value being randomly changed.

[0036] Clustering may also be performed using the hierarchical clustering disclosed in Non-Patent Document 1. Fig. 5 shows an image of the hierarchical clustering in Non-Patent Document 1.

[0037] The destination candidate calculation unit 32 moves the base station device 10 (on a computer) to the center of gravity of each cluster, and obtains location candidates where the predicted communication quality after the move (the predicted communication quality at the terminal device 20) is equal to or greater than a predetermined value. In other words, it calculates destination location candidates for each base station device 10 where communication with the terminal device 20 satisfies the required quality.

[0038] For example, suppose the target base station devices are BS1 and BS2, and the BS location candidates (denoted as (BS, P)) obtained based on two clustering runs with different initial values ​​are {(BS1, P11), (BS2, P21)} and {(BS1, P12), (BS2, P22)}.

[0039] In this case, for example, if the predicted communication quality of only {(BS1, P11), (BS2, P21)} of the two locations is equal to or greater than a predetermined value, {(BS1, P11), (BS2, P21)} becomes a location candidate.

[0040] The method for calculating the predicted communication quality is not limited to a specific method, but for example, the visibility area ratio, the predicted throughput integrated value, or the rate of terminals achieving the required quality can be used.

[0041] The visibility area ratio is the ratio of the area of ​​the target area to the area of ​​the area where the terminal devices 20 are present and where the base station devices 10 can be seen from the terminal devices 20 (i.e., there are no obstacles between the terminal devices 20 and the base station 10). For example, by dividing the target area into mesh areas, it is possible to find the area of ​​the area where the terminal devices 20 are present and where the base station devices 10 can be seen from the terminal devices 20.

[0042] As an example, if BS1 and BS2 exist and their respective locations are P11 and P21, and the visibility area ratio for terminal device 20 under BS1 (within BS1's cluster) is 30%, and the visibility area ratio for terminal device 20 under BS2 (within BS2's cluster) is 20%, then the visibility area ratio for {(BS1, P11), (BS2, P21)} is 50%.

[0043] The integrated predicted throughput value is a value obtained by integrating (summing up) the predicted throughputs of the terminal device 20 for all of the target terminal devices 20. The throughput can be estimated from the received power of the signal from the base station device 10 at the terminal device 20.

[0044] The required quality achievement terminal rate is the rate of terminal devices 20 that achieve the required quality among all target terminal devices 20. The required quality is, for example, throughput. As described above, throughput can be estimated from received power, so by comparing the estimated throughput with the required quality, it can be determined for each terminal device 20 whether the required quality is achieved.

[0045] Note that performing terminal clustering, as in calculation method example 1, has the effect of reducing the amount of calculation. If clustering is not performed, the path loss between each base station device and all terminal devices in the target area is calculated for all combinations of BS placement, as explained in calculation method example 2, to determine the reception quality at the terminal point, which can result in a large amount of calculation depending on the conditions. In contrast, performing terminal clustering makes it possible to calculate the path loss between the terminal devices included in each cluster and the corresponding base station device, thereby reducing the amount of calculation and determining the BS placement.

[0046] Calculation method example 2: The destination candidate determination unit 32 calculates the predicted communication quality for all possible location candidates of the base station device 10, and obtains location candidates whose predicted communication quality is equal to or greater than a predetermined value. An example of the method for calculating the predicted communication quality is as described above.

[0047] For example, suppose the target base station devices are BS1 and BS2, and the possible location candidates for the BSs (denoted as (BS, P)) are {(BS1, P11), (BS2, P21)} and {(BS1, P12), (BS2, P22)}.

[0048] In this case, for example, if the predicted communication quality of only {(BS1, P11), (BS2, P21)} among the above two locations (locations of each BS) is equal to or greater than a predetermined value, {(BS1, P11), (BS2, P21)} becomes a location candidate.

[0049] <s103> In S103, the destination position determination unit 33 calculates the travel cost from the home position of each base station device 10 to the destination. The travel cost is not limited to a specific one, but may be, for example, the travel distance from the home position to the destination position, the power consumption required to travel from the home position to the destination position, or the time required to travel from the home position to the destination position. The power consumption required for travel can be calculated by multiplying the travel distance by the power consumption per unit travel distance, which has been obtained in advance. The time required for travel can be calculated by multiplying the travel distance by the time per unit travel distance, which has been obtained in advance.

[0050] This will be explained using a specific example. The position P of the BS is represented as (BS, P). As a result of S102, two candidates for the destination position are obtained: "Candidate 1: {(BS1, P1A), (BS2, P2A)}" and "Candidate 2: {(BS1, P1B), (BS2, P2B)}." In addition, the home position of the BS is represented as {(BS1, HP1), (BS2, HP2)}.

[0051] The destination position determination unit 33 calculates the travel cost of each BS in candidate 1 as follows: for BS1, it calculates C1A as the travel cost required to travel from HP1 to P1A, and for BS2, it calculates C2A as the travel cost required to travel from HP2 to P2A.

[0052] In addition, the destination position determination unit 33 calculates the travel cost of each BS in candidate 2 as follows: for BS1, it calculates C1B as the travel cost required to travel from HP1 to P1B, and for BS2, it calculates C2B as the travel cost required to travel from HP2 to P2B.

[0053] <s104> In S104, the destination position determination unit 33 determines the destination position of each base station device 10 based on the movement cost calculated in S103. As examples of specific destination position determination methods, there are the following determination method 1 and determination method 2.

[0054] Determination method 1: For each destination position candidate, the destination position determination unit 33 obtains the sum of the movement costs for all the target base station devices 10, and selects the destination position candidate with the minimum sum of the movement costs as the final destination position.

[0055] In the above specific example, the destination position determination unit 33 calculates “C1A + C2A” as the sum of the movement costs in candidate 1, and calculates “C1B + C2B” as the sum of the movement costs in candidate 2.

[0056] If the destination position determination unit 33 determines that “(C1A + C2A) < (C1B + C2B)”, then since the movement cost of candidate 1 is smaller than that of candidate 2, candidate 1 is selected as the final destination position.

[0057] Determination method 2: For each destination position candidate, the destination position determination unit 33 obtains the maximum movement cost among the movement costs of all the target base station devices 10, and selects the destination position candidate with the minimum maximum movement cost as the final destination position.

[0058] In the above specific example, assume that C1A is larger than C2A among the movement costs of the two BSs in candidate 1. Also, assume that C2B is larger than C1B among the movement costs of the two BSs in candidate 2.

[0059] If the destination position determination unit 33 determines that “C1A < C2B)”, then since the maximum movement cost in candidate 1 is smaller than the maximum movement cost in candidate 2, candidate 1 is selected as the final destination position.

[0060] <s105> In S105, the control unit 34 executes control to move each base station device 10 based on the determination result in S104.

[0061] (Example of hardware configuration) The control device 30 can be realized, for example, by causing a computer to execute a program. This computer may be a physical computer or a virtual machine on the cloud.

[0062] That is, the control device 30 can be realized by using hardware resources such as a CPU and memory built into a computer to execute a program corresponding to the processing performed by the control device 30. The program can be recorded on a computer-readable recording medium (such as a portable memory) and can be saved or distributed. The program can also be provided via a network such as the Internet or email.

[0063] Fig. 6 is a diagram showing an example of the hardware configuration of the computer. The computer in Fig. 6 includes a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, an output device 1008, and the like, all of which are interconnected via a bus BS.

[0064] A program for realizing processing on the computer is provided by a recording medium 1001 such as a CD-ROM or a memory card. When the recording medium 1001 storing the program is set in the drive device 1000, the program is installed from the recording medium 1001 to the auxiliary storage device 1002 via the drive device 1000. However, the program does not necessarily have to be installed from the recording medium 1001, but may be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files, data, etc.

[0065] When an instruction to start a program is received, the memory device 1003 reads the program from the auxiliary storage device 1002 and stores it. The CPU 1004 implements functions related to the control device 30 in accordance with the program stored in the memory device 1003. Specifically, the CPU 1004 executes, for example, the procedure shown in FIG.

[0066] The interface device 1005 is used as an interface for connecting to a network, etc. The display device 1006 displays a GUI (Graphical User Interface) etc. according to a program. The input device 1007 is composed of a keyboard, mouse, buttons, a touch panel, etc., and is used to input various operation instructions. The output device 1008 outputs the calculation results.

[0067] (Effects of the embodiment) As described above, in the technology according to the present embodiment, the destination location is determined taking into consideration the travel cost, so that when performing mobility control on the mobile radio station device, it is possible to suppress the deterioration of communication quality during movement and to suppress the increase in power consumption due to movement.

[0068] In this embodiment, it is possible to suppress deterioration of communication quality and power consumption during movement, particularly when the movement route of the terminal device is unpredictable and the mobile radio station device moves continuously.

[0069] More specifically, in this embodiment, control is performed to always reduce the moving distance or moving time from the same home position, so when multiple movements are assumed, the quality degradation time during the entire (series) movement of the mobile radio station device can be minimized without predicting the terminal position. The technology according to this embodiment is suitable for cases where the mobile radio station device moves relatively frequently. When selecting an optimal position taking into account only each movement, there is a possibility that movements with extremely high movement costs will occur depending on the conditions, but the technology according to this embodiment makes it possible to avoid this.

[0070] Furthermore, since the system performs control to reduce the power required for movement, the system can be operated with low power consumption, especially when continuous movement is assumed.

[0071] (Addendum) This specification discloses at least the wireless communication system, control device, destination position determining method, and program described in the following sections. (Additional note 1) A wireless communication system comprising one or more mobile radio station devices that communicate with one or more terminal devices, and a control device, The control device calculating a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device based on the location of each terminal device; Among the plurality of destination position candidates, a destination position candidate for which the sum of the movement costs for the mobile radio station devices required for movement from the home position to the destination is the smallest, or a destination position candidate for which the maximum value of the movement costs for the one or more mobile radio station devices required for movement from the home position to the destination is the smallest, is selected as the destination position for movement control. Wireless communication system. (Additional note 2) The control device calculates destination position candidates for each mobile radio station device by performing clustering on the terminal devices. Item 1. A wireless communication system according to claim 1. (Additional note 3) A control device in a wireless communication system including one or more mobile radio station devices that communicate with one or more terminal devices, the control device comprising: Memory and at least one processor coupled to said memory; Including, The processor: calculating a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device based on the location of each terminal device; Among the plurality of destination position candidates, a destination position candidate for which the sum of the movement costs for the mobile radio station devices required for movement from the home position to the destination is the smallest, or a destination position candidate for which the maximum value of the movement costs for the one or more mobile radio station devices required for movement from the home position to the destination is the smallest, is selected as the destination position for movement control. Control device. (Additional note 4) The processor calculates destination position candidates for each mobile radio station device by performing clustering on the terminal devices. The control device according to claim 3. (Additional note 5) A method for determining a destination position in a wireless communication system including one or more mobile wireless station devices that communicate with one or more terminal devices and a control device, comprising: a step in which the control device calculates, based on the position of each terminal device, a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device; a step in which the control device selects, from among the plurality of destination location candidates, a destination location candidate for which the sum of the movement costs for the mobile radio station devices required for movement from the home position to the destination is the smallest, or a destination location candidate for which the maximum value of the movement costs for the movement from the home position to the destination among one or more mobile radio station devices is the smallest, as a destination location for movement control; A destination position determination method comprising: (Additional note 6) A non-transitory storage medium storing a program for causing a computer to function as each part of the control device described in appended paragraph 3 or 4.

[0072] Although the present embodiment has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0073] 10 Base station equipment 11 Drive unit 20 Terminal equipment 30 Control device 31 Terminal location acquisition unit 32 Destination candidate calculation unit 33 Destination position determination unit 34 Control Unit 35 Environmental Understanding Department 1000 Drive Device 1001 Recording media 1002 Auxiliary storage device 1003 Memory device 1004 CPU 1005 Interface device 1006 Display device 1007 Input Device 1008 Output Device

Claims

1. A wireless communication system including a plurality of mobile radio station devices that communicate with one or more terminal devices, and a control device, The control device calculating a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device based on the location of each terminal device; Among the plurality of destination position candidates, the destination position candidate for which the maximum value of the movement cost required for movement from the home position to the destination among the plurality of mobile radio station devices is the smallest is selected as the destination position for movement control. Wireless communication system.

2. The control device calculates destination position candidates for each mobile radio station device by performing clustering on the terminal devices.

10. The wireless communication system of claim 1.

3. A control device in a wireless communication system including a plurality of mobile radio station devices that communicate with one or more terminal devices, the control device comprising: a destination candidate calculation unit that calculates a plurality of destination position candidates for each mobile radio station device that satisfy a required quality of communication with the terminal device based on the location of each terminal device; a destination position determining unit that selects, from among the plurality of destination position candidates, the destination position candidate that has the smallest maximum value of the movement cost required for movement from the home position to the destination among the plurality of mobile radio station devices, as the destination position for movement control; A control device comprising:

4. The destination candidate calculation unit calculates destination position candidates for each mobile radio station device by performing clustering on the terminal devices. The control device according to claim 3 .

5. A method for determining a destination position in a wireless communication system including a plurality of mobile wireless station devices that communicate with one or more terminal devices and a control device, comprising: a step in which the control device calculates, based on the position of each terminal device, a plurality of candidate destination locations for each mobile radio station device that satisfy a required quality of communication with the terminal device; a step in which the control device selects, from among the plurality of destination position candidates, a destination position candidate which has the smallest maximum value of movement costs required for movement from a home position to the destination among the plurality of mobile radio station devices, as a destination position for movement control; A destination position determination method comprising:

6. A program for causing a computer to function as each unit in the control device according to claim 3 or 4.

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