Wireless communication system, control station, wireless communication control method, and control program

Abstract

This enables the efficient provision of wireless communication services using multiple mobile base stations. [Solution] A wireless communication system according to one embodiment includes a plurality of mobile base stations, each accommodating wireless terminals located around a moving path, and a fixed base station that forms a wireless communication network together with the plurality of mobile base stations, and provides wireless communication services within a predetermined area. The wireless communication system includes an acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area, and environmental information indicating the environment affecting the propagation path of radio waves within the predetermined area, and a control unit that controls the moving path and speed of each of the plurality of mobile base stations, as well as the topology of the wireless communication network, based on the distribution information and environmental information, so that the number of wireless terminals or the amount of traffic accommodated by each of the plurality of mobile base stations is balanced.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, a control station, a wireless communication control method, and a control program. Background Art

[0002] In wireless communication systems such as the fifth-generation mobile communication system (5G), mobile base stations, in which mobile stations such as ships, automobiles, and unmanned aerial vehicles (drones) are equipped with wireless communication functions to operate as base stations, have attracted attention (see, for example, Non-Patent Document 1).

[0003] Mobile base stations are effective as an emergency means for constructing communication infrastructure during large-scale disasters, and drone-based mobile base stations in particular are important in that they can easily provide communication services to isolated areas.

[0004] Since drone base stations operate on batteries, it is necessary to construct a communication system that can be implemented with low power consumption. In particular, when transmitting large-capacity information, it is important to achieve high communication efficiency while maintaining low power consumption. As a method for this purpose, an air-to-ground wireless network using circularly orbiting drone base stations has been proposed (see, for example, Non-Patent Documents 2 and 3).

[0005] For example, the conventional technology utilizes the property that drones consume less power when moving at an appropriate speed than when hovering in the air, and achieves high energy efficiency by constantly causing a plurality of drone base stations to orbit in a circle (see, for example, Non-Patent Document 4). Here, energy efficiency means communication capacity relative to power consumption. Prior Art Documents Non-Patent Documents

[0006] Non-Patent Document 1 "Information and Communication Situation during the 2024 Noto Peninsula Earthquake," [online], Ministry of Internal Affairs and Communications Information and Communications White Paper (2024 Edition), Part I, Special Feature 1: Website, [Accessed February 19, 2025], Internet <URL: https: / / www.soumu.go.jp / johotsusintokei / whitepaper / ja / r06 / html / nd112420.html> [Non-Patent Document 2] Wang Ziyan, et al., "Basic Performance Evaluation of Air-to-Ground Networks Using Circular-Rotating UAV Base Stations," IEICE General Conference, B-11-01, March 2024. [Non-Patent Document 3] Wang Ziyan, et al., "Performance Evaluation of Air-to-Ground Network Using Circular Orbiting UAV Base Stations Considering User Density," IEICE Technical Report, vol. 124, no. 191, CQ2024-50, pp. 42-47, September 2024. [Non-Patent Document 4] Y. Zeng, J. [Overview of the project] [Problems that the invention aims to solve]

[0007] Traditionally, drone base stations have always moved at a constant speed. However, in areas where drone base stations are flying, if there are no users on the ground using wireless terminals, or if there are many obstacles such as buildings, there are many periods when wireless communication services cannot be provided efficiently.

[0008] Furthermore, conventionally, the movement routes of drone base stations were set with the aim of ensuring communication quality and accommodating as much traffic as possible for ground users using wireless terminals. However, since user traffic accommodated by drone base stations is aggregated to fixed base stations and then forwarded from fixed base stations to the backbone network, setting the routes of drone base stations considering only the wireless terminals used by ground users resulted in the problem of traffic concentrating on specific drone base stations, such as those located near fixed base stations.

[0009] The present invention has been made in view of the above-mentioned problems, and aims to provide a wireless communication system, a control station, a wireless communication control method, and a control program that enable efficient provision of wireless communication services using multiple mobile base stations. [Means for solving the problem]

[0010] A wireless communication system according to one embodiment of the present invention comprises a plurality of mobile base stations, each accommodating wireless terminals located around a moving path, and a fixed base station that, together with the plurality of mobile base stations, constitutes a wireless communication network, and provides wireless communication services within a predetermined area. The wireless communication system is characterized by having an acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area and environmental information indicating the environment affecting the propagation path of radio waves within the predetermined area, and a control unit that controls the moving path and speed of each of the plurality of mobile base stations, as well as the topology of the wireless communication network, based on the distribution information and the environmental information, so as to balance the number of wireless terminals or the amount of traffic accommodated by each of the plurality of mobile base stations.

[0011] Furthermore, a control station according to one embodiment of the present invention is a control station that controls wireless communication services provided within a predetermined area by a plurality of mobile base stations, each accommodating wireless terminals located around a moving path, and a fixed base station that constitutes a wireless communication network together with the plurality of mobile base stations, and is characterized by having an acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area and environmental information indicating the environment affecting the propagation path of radio waves within the predetermined area, and a control unit that controls the moving path and moving speed of each of the plurality of mobile base stations, as well as the topology of the wireless communication network, based on the distribution information and the environmental information, so as to balance the number of wireless terminals or the amount of traffic accommodated by each of the plurality of mobile base stations.

[0012] Furthermore, a wireless communication control method according to one embodiment of the present invention is a wireless communication control method performed by a wireless communication system that provides wireless communication services within a predetermined area, comprising a plurality of mobile base stations each accommodating wireless terminals located around a moving path, and a fixed base station that constitutes a wireless communication network together with the plurality of mobile base stations, characterized in that it includes an acquisition step of acquiring distribution information indicating the distribution of wireless terminals located within the predetermined area and environmental information indicating the environment affecting the propagation path of radio waves within the predetermined area, and a control step of controlling the moving path and moving speed of each of the plurality of mobile base stations, as well as the topology of the wireless communication network, based on the distribution information and the environmental information, so as to balance the number of wireless terminals or the amount of traffic accommodated by each of the plurality of mobile base stations.

[0013] Furthermore, a control program according to one embodiment of the present invention is a control program executed by a control station that controls wireless communication services provided within a predetermined area by a plurality of mobile base stations, each accommodating wireless terminals located around a moving path, and a fixed base station that constitutes a wireless communication network together with the plurality of mobile base stations, wherein the control station functions as a computer, and each part of the control station includes: an acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area and environmental information indicating the environment affecting the propagation path of radio waves within the predetermined area; and a control unit that controls the moving path and moving speed of each of the plurality of mobile base stations, as well as the topology of the wireless communication network, so that the number of wireless terminals or the amount of traffic accommodated by each of the plurality of mobile base stations is balanced based on the distribution information and the environmental information. [Effects of the Invention]

[0014] According to the present invention, it becomes possible to efficiently provide wireless communication services using multiple mobile base stations. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an overview of a wireless communication system according to one embodiment. [Figure 2] This figure shows a more specific configuration example of a wireless communication system according to one embodiment. [Figure 3] This diagram illustrates the relationship between the speed and time of a mobile base station circling along a predetermined path. [Figure 4] This diagram schematically shows the topology of a wireless communication system based on the control of the control unit. [Figure 5] This figure shows an example of the hardware configuration of a control station according to one embodiment. [Modes for carrying out the invention]

[0016] A radio communication system 10 according to an embodiment is described below with reference to the drawings. FIG. 1 is a diagram outlining the radio communication system 10 according to an embodiment.

[0017] As shown in FIG. 1, the radio communication system 10 according to an embodiment includes, for example, a fixed base station 20 fixed to the ground, a plurality of mobile base stations 30, and a control station 40. The mobile base station 30 is, for example, a drone base station that moves by flying. The control station 40 controls radio communication services provided by the radio communication system 10.

[0018] The radio communication system 10 provides radio communication services within a predetermined area by, for example, the plurality of mobile base stations 30 each accommodating radio terminals 60 located around a turning flight (moving) route, and the fixed base station 20 that forms a radio communication network together with the plurality of mobile base stations 30.

[0019] Here, an air-to-ground network is formed between the radio terminals 60 and the mobile base stations 30. Furthermore, an airborne network is formed between the plurality of mobile base stations 30 and the fixed base station 20.

[0020] Then, the control station 40 adaptively sets the movement route and movement speed of each mobile base station 30 based on the distribution of ground users who use the radio terminals 60 within the predetermined area where the radio communication service is provided, and topographic and map information within the predetermined area.

[0021] The plurality of mobile base stations 30 cooperate with each other under the control of the control station 40, and balance the number of accommodated users (radio terminals 60) and energy efficiency, respectively. Then, the radio communication system 10 distributes traffic generated within the predetermined area to the plurality of mobile base stations 30, thereby providing radio communication services efficiently over a long period of time.

[0022] Figure 2 shows a more specific configuration example of a wireless communication system 10 according to one embodiment. The fixed base station 20 is a base station fixed at a predetermined location on the ground as described above, and performs wireless communication by connecting with at least one of the multiple mobile base stations 30.

[0023] The mobile base station 30 is, for example, a drone base station. Each mobile base station 30 is equipped with, for example, a control unit 300, a transmitting / receiving unit 302, a route / speed control unit 304, a topology control unit 306, and a propagation path estimation unit 308, and operates in a circular flight (movement) in accordance with the control of the control station 40, and accommodates wireless terminals 60 located around the route of the circular flight (movement).

[0024] The control unit 300 controls each component of the mobile base station 30. The transmitting / receiving unit 302 performs wireless communication with the wireless terminal 60, other mobile base stations 30, and the control station 40.

[0025] The route and speed control unit 304 controls the flight path and flight speed of the mobile base station 30. The topology control unit 306 controls the topology of the wireless communication system 10 together with other mobile base stations 30 in accordance with the control of the control station 40. The propagation path estimation unit 308 estimates propagation path information that shows the propagation paths around the mobile base station 30.

[0026] The control station 40 has an estimation unit 400, an observation unit 402, an acquisition unit 404, and a control unit 406, and communicates with multiple mobile base stations 30 and fixed base stations 20 via a transceiver unit (not shown). The control station 40 acquires information such as propagation path information, traffic volume, travel path coordinates, and travel speed from each of the multiple mobile base stations 30, and controls the travel paths and travel speeds of the multiple mobile base stations 30, as well as the topology of the wireless communication system 10, so that the wireless communication system 10 can efficiently provide wireless communication services.

[0027] For example, the estimation unit 400 estimates the air-to-ground propagation path characteristics at the location of the user using the wireless terminal 60, and outputs information indicating the estimation result to the acquisition unit 404. The air-to-ground propagation path characteristics may be accurate propagation path coefficients, or they may be simplified information indicating whether the wireless terminal 60 used by the user at each location can connect to the mobile base station 30. The estimation unit 400 may also estimate the traffic volume of each mobile base station 30.

[0028] The observation unit 402 observes the ground distribution of users using the wireless terminal 60 and outputs information indicating the observation results to the acquisition unit 404. The observation unit 402 may also observe the distribution of users using the wireless terminal 60 and the amount of traffic handled by each mobile base station 30 via the mobile base station 30.

[0029] The acquisition unit 404 acquires distribution information showing the distribution of wireless terminals 60 located within a predetermined area providing wireless communication services, and environmental information showing the environment affecting the propagation path of radio waves within the predetermined area, based on the information output by the estimation unit 400 and the observation unit 402, and outputs these to the control unit 406. The acquisition unit 404 may also be configured to acquire user density distributions, etc., held by telecommunications carriers, etc.

[0030] Based on the distribution information and environmental information output by the acquisition unit 404, the control unit 406 controls the travel paths and travel speeds of each of the multiple mobile base stations 30, as well as the topology of the wireless communication network in the wireless communication system 10, so that the number of wireless terminals 60 accommodated by each of the multiple mobile base stations 30 or the amount of traffic are balanced.

[0031] Furthermore, the control unit 406 may calculate the amount of traffic and communication quality that the mobile base station 30 will accommodate in its current mobile path, based on the propagation path information and distribution information. Various indicators such as throughput and signal-to-noise ratio can be used for communication quality. Communication quality may also be the average or minimum value of the wireless terminal 60 connected to the mobile base station 30.

[0032] Furthermore, the control unit 406 may determine the mobile path of each mobile base station 30 and the topology of the airborne network based on the traffic volume and communication quality, so that each wireless terminal 60 meets a predetermined communication quality and satisfies the requirements of the airborne network. The requirements of the airborne network include, for example, minimizing the load on the traffic volume to be accommodated.

[0033] Subsequently, the control unit 406 notifies each of the multiple mobile base stations 30 of the travel route and network topology via a transmitting / receiving unit (not shown).

[0034] Then, each of the multiple mobile base stations 30 orbits the air based on the notified information and connects to other mobile base stations 30 or the like, which become adjacent nodes.

[0035] Furthermore, if the control unit 406 has a first area within a predetermined area for providing wireless communication services where wireless terminals 60 are distributed, and a second area where the density of wireless terminals 60 is lower than that of the first area, it individually controls the movement speed of each mobile base station 30.

[0036] Figure 3 illustrates the relationship between the movement speed and time of a mobile base station 30 that rotates along a predetermined movement path.

[0037] For example, the control unit 406 controls the mobile base station 30 to move along a predetermined path at a first movement speed in a first region where wireless terminals 60 are distributed, and to move along a predetermined path at a second movement speed faster than the first movement speed in a second region where the density of wireless terminals 60 is lower than in the first region.

[0038] As a result, the wireless communication system 10 can reduce the power consumption of the batteries of each mobile base station 30 and efficiently provide wireless communication services.

[0039] Figure 4 schematically shows the topology of the wireless communication system 10 based on the control of the control unit 406. For example, the control unit 406 controls the mobile paths and connections of each mobile base station 30 so that the load of traffic that each mobile base station 30 transfers to the fixed base station 20 is evenly distributed.

[0040] For example, the mobile base station 30 can accommodate more traffic the longer its travel path is when turning.

[0041] At this time, the control unit 406 controls the mobile base station 30 so that the mobile path length of the mobile base station 30 that receives a large amount of traffic from other mobile base stations 30 is shorter than the mobile path length of the mobile base station 30 that receives a small amount of traffic from other mobile base stations 30. In other words, the mobile base station 30 shortens its mobile path length and reduces the number of ground-based wireless terminals 60 it accommodates.

[0042] Furthermore, the control unit 406 controls the movement paths of mobile base stations 30 so that areas closer to the fixed base station 20 include more mobile base stations 30 than areas farther away from the fixed base station 20. In other words, the control unit 406 controls the movement paths of mobile base stations 30 so that there are more mobile base stations 30 as they get closer to the fixed base station 20, thereby distributing the traffic load of each mobile base station 30.

[0043] Thus, the wireless communication system 10 according to one embodiment controls the travel path and travel speed of each of the multiple mobile base stations 30, as well as the topology of the wireless communication network, making it possible to efficiently provide wireless communication services.

[0044] Furthermore, each function of the control station 40 may be partially or entirely comprised of hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or it may be comprised of a program executed by a processor such as a CPU.

[0045] For example, the control station 40 can be implemented using a computer and a program, and the program can be recorded on a storage medium or provided via a network. Furthermore, each function of the control station 40 may be configured to be provided by either the fixed base station 20 or the mobile base station 30.

[0046] Figure 5 shows an example of the hardware configuration of a control station 40 according to one embodiment. As shown in Figure 5, for example, the control station 40 has an input unit 50, an output unit 51, a communication unit 52, a CPU 53, a memory 54, and an HDD 55 connected via a bus 56, and is equipped with computer functions. The control station 40 is also configured to input and output data to and from a computer-readable storage medium 57.

[0047] The input unit 50 is, for example, a keyboard and mouse. The output unit 51 is, for example, a display device such as a display that outputs images. The communication unit 52 is, for example, a wireless network interface.

[0048] The CPU 53 controls each component of the control station 40 and performs predetermined processing. The memory 54 and HDD 55 are storage units that store data, etc.

[0049] The storage medium 57 is capable of storing programs and the like that which cause the control station 40 to execute its functions. Note that the architecture of the control station 40 is not limited to the example shown in Figure 5. [Explanation of symbols]

[0050] 10... Wireless communication system, 20... Fixed base station, 30... Mobile base station, 40... Control station, 50... Input unit, 51... Output unit, 52... Communication unit, 53... CPU, 54... Memory, 55... HDD, 56... Bus, 57... Storage medium, 60... Wireless terminal, 300... Control unit, 302... Transmit / receive unit, 304... Route / speed control unit, 306... Topology control unit, 308... Propagation path estimation unit, 400... Estimation unit, 402... Observation unit, 404... Acquisition unit, 406... Control unit

Claims

1. A wireless communication system that provides wireless communication services within a predetermined area, comprising a plurality of mobile base stations each accommodating wireless terminals located around a moving path, and a fixed base station that, together with the plurality of mobile base stations, constitutes a wireless communication network, An acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area, and environmental information indicating the environment that affects the propagation path of radio waves within the predetermined area, Based on the distribution information and the environmental information, a control unit controls the travel path and travel speed of each of the multiple mobile base stations, as well as the topology of the wireless communication network, so that the number of wireless terminals or the amount of traffic accommodated by each of the multiple mobile base stations is balanced. A wireless communication system characterized by having the following features.

2. The control unit, When a predetermined area includes a first area where wireless terminals are distributed and a second area where the density of wireless terminals is lower than that of the first area, the mobile base station is controlled to move along a predetermined path at a first speed in the first area, and to move along a predetermined path at a second speed faster than the first speed in the second area. The wireless communication system according to claim 1, characterized by the following:

3. The control unit, Control the mobile base station so that the travel path length of a mobile base station receiving a large amount of traffic from other mobile base stations is shorter than the travel path length of a mobile base station receiving a small amount of traffic from other mobile base stations. The wireless communication system according to claim 1, characterized by the following:

4. The control unit, Control the system so that areas with a short distance from the fixed base station include more mobile base station travel paths than areas with a long distance from the fixed base station. The wireless communication system according to claim 1, characterized by the following:

5. In a control station that controls wireless communication services provided within a predetermined area by multiple mobile base stations, each accommodating wireless terminals located around a moving path, and fixed base stations that constitute a wireless communication network together with the multiple mobile base stations, An acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area, and environmental information indicating the environment that affects the propagation path of radio waves within the predetermined area, Based on the distribution information and the environmental information, a control unit controls the travel path and travel speed of each of the multiple mobile base stations, as well as the topology of the wireless communication network, so that the number of wireless terminals or the amount of traffic accommodated by each of the multiple mobile base stations is balanced. A control station characterized by having the following features.

6. The control unit, When a predetermined area includes a first area where wireless terminals are distributed and a second area where the density of wireless terminals is lower than that of the first area, the mobile base station is controlled to move along a predetermined path at a first speed in the first area, and to move along a predetermined path at a second speed faster than the first speed in the second area. The control station according to claim 5, characterized in that

7. A wireless communication control method performed by a wireless communication system that provides wireless communication services within a predetermined area, comprising a plurality of mobile base stations each accommodating wireless terminals located around a moving path, and a fixed base station that, together with the plurality of mobile base stations, constitutes a wireless communication network, An acquisition step of acquiring distribution information showing the distribution of wireless terminals located within the predetermined area, and environmental information showing the environment that affects the propagation path of radio waves within the predetermined area, Based on the distribution information and the environmental information, a control step controls the movement path and movement speed of each of the multiple mobile base stations, as well as the topology of the wireless communication network, so that the number of wireless terminals or the amount of traffic accommodated by each of the multiple mobile base stations is balanced. A wireless communication control method characterized by including the following:

8. In a control program executed by a control station that controls wireless communication services provided within a predetermined area by multiple mobile base stations, each accommodating wireless terminals located around a moving path, and fixed base stations that constitute a wireless communication network together with the multiple mobile base stations, An acquisition unit that acquires distribution information indicating the distribution of wireless terminals located within the predetermined area, and environmental information indicating the environment that affects the propagation path of radio waves within the predetermined area, Based on the distribution information and the environmental information, a control unit controls the travel path and travel speed of each of the multiple mobile base stations, as well as the topology of the wireless communication network, so that the number of wireless terminals or the amount of traffic accommodated by each of the multiple mobile base stations is balanced. A control program for causing a computer to function as each part of the control station having the above-mentioned components.

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