Wireless communication system, terminal, wireless communication method, and wireless communication program

Abstract

A wireless communication system according to one embodiment comprises: a terminal; and a relay device that transmits a beacon signal and a data signal at a timing with high periodicity and high reproducibility while moving. The terminal comprises: a communication unit that receives the beacon signal transmitted by the relay device; a storage unit that stores the reception time and reception strength of the beacon signal received by the communication unit; an estimation unit that estimates a timing at which the relay device next transmits the beacon signal and the data signal on the basis of the reception time and reception strength stored by the storage unit; and a control unit that performs control such that the communication unit starts to transmit / receive the data signal to / from the relay device at the timing estimated by the estimation unit.

Description

Wireless communication system, terminal, wireless communication method, and wireless communication program

[0001] The present invention relates to a wireless communication system, a terminal, a wireless communication method, and a wireless communication program.

[0002] To build a mobile network, technologies that use geostationary satellites (GEO: geostationary orbit), low earth orbit satellites (LEO: low earth orbit), high altitude platform stations (HAPS: high altitude pseudo satellites), airplanes, drones, etc. are known (see, for example, Non-Patent Document 1).

[0003] Low Earth orbit (LEO), which is an orbit around the Earth at an altitude of 2,000 km or less, is a communication system that has various advantages because it is closer to the Earth's surface than geostationary orbit (GEO).

[0004] Wei Feng, et al. "UAV-aided MIMO communications for 5G Internet of Things", IEEE Internet of Things Journal, VOL. 6, NO. 2, APRIL 2019,p.1731-1740

[0005] However, the time during which a low-earth orbit satellite and a terrestrial terminal (terminal) can communicate is affected by the orbital information of the low-earth orbit satellite and the surrounding environment. Therefore, in the past, in order for a terminal to perform wireless communication at a specific time, the terminal had to acquire orbital information of the low-earth orbit satellite and perform calculations, or the terminal had to receive an external activation signal.

[0006] Furthermore, in order to establish communication with low-earth orbit satellites, the terminal may consume a lot of power in its arithmetic circuits and receiving circuits, leading to an increase in size and cost.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless communication system, terminal, wireless communication method, and wireless communication program that enable efficient establishment of communication with a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving.

[0008] A wireless communication system according to one embodiment of the present invention is a wireless communication system having a terminal and a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving, wherein the terminal has a communication unit that receives the beacon signals transmitted by the relay device, a memory unit that stores the reception time and reception strength of the beacon signals received by the communication unit, an estimation unit that estimates the timing at which the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit, and a control unit that controls the communication unit to start transmitting and receiving data signals with the relay device at the timing estimated by the estimation unit.

[0009] In addition, a terminal according to one embodiment of the present invention is a terminal that performs wireless communication with a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving, and is characterized by having: a communication unit that receives the beacon signals transmitted by the relay device; a memory unit that stores the reception time and reception strength of the beacon signals received by the communication unit; an estimation unit that estimates the timing at which the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit; and a control unit that controls the communication unit to start transmitting and receiving data signals with the relay device at the timing estimated by the estimation unit.

[0010] Furthermore, a wireless communication method according to one embodiment of the present invention is a wireless communication method in which a terminal communicates wirelessly with a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving, and is characterized by including a receiving step of receiving the beacon signal transmitted by the relay device, a storage step of storing the reception time and reception strength of the beacon signal received by the receiving step, an estimation step of estimating the timing at which the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored by the storage step, and a control step of controlling the relay device to start transmitting and receiving a data signal at the timing estimated by the estimation step.

[0011] In addition, a wireless communication program according to one embodiment of the present invention is a wireless communication program executed by a terminal that performs wireless communication with a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving, and causes a computer to function as each part of the terminal having a communication unit that receives the beacon signals transmitted by the relay device, a memory unit that stores the reception time and reception strength of the beacon signals received by the communication unit, an estimation unit that estimates the timing when the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit, and a control unit that controls the communication unit to start transmitting and receiving data signals with the relay device at the timing estimated by the estimation unit.

[0012] According to the present invention, it is possible to efficiently establish communication with a relay device that transmits beacon signals and data signals at highly periodic and repeatable timings while moving.

[0013] FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment. FIG. 2 is a functional block diagram illustrating a configuration example of a terminal according to an embodiment. FIG. 3 is a diagram illustrating a first operation example of a wireless communication system according to an embodiment. FIG. 4 is a diagram illustrating an example of reception time and field strength stored by a terminal according to an embodiment. FIG. 5 is a diagram illustrating a second operation example of a wireless communication system according to an embodiment. FIG. 6 is a diagram schematically illustrating a result of estimating transmission and reception timing of a data signal based on reception time and field strength actually measured by a terminal according to an embodiment. FIG. 7 is a diagram illustrating an example of a hardware configuration of a terminal according to an embodiment.

[0014] A wireless communication system according to an embodiment will be described below with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a wireless communication system 1 according to an embodiment. As shown in Fig. 1, in the wireless communication system 1 according to an embodiment, communication is relayed to a terminal (terrestrial terminal) 3 that performs wireless communication with a base station 2 by at least one of a HAPS 4, a low earth orbit satellite (sun-synchronous orbit, sun-synchronous quasi-recurrent orbit, etc.) 5, and a geostationary satellite 6.

[0015] In other words, the HAPS 4, the low-earth orbit satellite 5, and the geostationary satellite 6 function as relay devices. The low-earth orbit satellite 5 also functions as a relay device that transmits beacon signals and data signals at highly periodic and repeatable timing while moving.

[0016] 2 is a functional block diagram illustrating an example configuration of a terminal 3 according to an embodiment. As illustrated in FIG. 2, the terminal 3 includes, for example, a communication unit 31, a storage unit 32, an estimation unit 33, and a control unit 34. The terminal 3 also includes at least one communication function corresponding to, for example, IMT-Advanced, Bluetooth (registered trademark), Wi-Fi (registered trademark), IoT (Internet of Things), and the like.

[0017] The communication unit 31 includes a receiving unit 310 and a transmitting unit 312. The receiving unit 310 receives, for example, a beacon signal transmitted by a low-earth orbit satellite 5. The transmitting unit 312 transmits a signal to the low-earth orbit satellite 5.

[0018] The storage unit 32 is configured to store the reception time and reception strength of the beacon signal received by the receiving unit 310 .

[0019] The estimation unit 33 estimates the timing at which the low-earth orbit satellite 5 will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the storage unit 32 .

[0020] The control unit 34 controls each unit constituting the terminal 3. For example, the control unit 34 controls the communication unit 31 to start transmitting and receiving a data signal to and from the low-earth orbit satellite (relay device) 5 at the timing estimated by the estimation unit 33.

[0021] Furthermore, when the control unit 34 controls the communication unit 31 to start transmitting and receiving data signals to and from the low-earth orbit satellite 5, the control unit 34 may also control the communication unit 31 to again receive a beacon signal transmitted by the low-earth orbit satellite 5 after a predetermined period has elapsed. In other words, the control unit 34 can make a correction to the orbit of the low-earth orbit satellite 5 after a predetermined period has elapsed.

[0022] Next, an operation example of the wireless communication system 1 will be described with reference to Figures 3 to 6. Figure 3 is a diagram showing a first operation example of the wireless communication system 1 according to an embodiment. As shown in Figure 3, first, the low-earth orbit satellite 5 transmits a beacon signal or the like to the terminal 3 (S100).

[0023] The terminal 3 receives a beacon signal or the like from the low-earth orbit satellite 5 (S200), stores the reception time and field strength (reception power) internally (S202), and then proceeds to the next second operation example of the wireless communication system 1. Fig. 4 is a diagram illustrating the reception time and field strength (reception power strength) stored by the terminal 3 according to one embodiment.

[0024] 5 is a diagram illustrating a second operation example of the wireless communication system 1 according to an embodiment. As illustrated in FIG. 5, the terminal 3 reads the reception time and the field strength from inside the terminal 3 (S300), and estimates (calculates) the transmission and reception timing of the data signal (S302).

[0025] 6 is a diagram illustrating an example of an estimation result of the transmission and reception timing of a data signal based on the reception time and field strength actually measured by the terminal 3 according to an embodiment. By estimating the transmission and reception timing of the data signal, the terminal 3 can obtain a timing that is likely to result in successful communication with the low-earth orbit satellite 5 (selection of communication parameters with a high frequency of success).

[0026] Then, the terminal 3 starts transmitting and receiving data to and from the low earth orbit satellite 5 at the calculated timing (S304). At this time, the low earth orbit satellite 5 starts transmitting and receiving data to and from the terminal 3 (S400).

[0027] In this way, the wireless communication system 1 estimates the timing when the low-orbit satellite 5 will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit 32, and controls the communication unit 31 to start transmitting and receiving data signals with the low-orbit satellite 5 at the estimated timing, so that communication can be efficiently established with the low-orbit satellite (relay device) 5 that transmits beacon signals and data signals at highly periodic and reproducible timing while moving.

[0028] Furthermore, since the terminal 3 can communicate with the low-earth orbit satellite 5 efficiently, it is configured to consume less power than conventional configurations.

[0029] In addition, each function possessed by terminal 3 may be configured in part or in whole by hardware such as a PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0030] For example, the terminal 3 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0031] 7 is a diagram illustrating an example of the hardware configuration of a terminal 3 according to an embodiment. As illustrated in FIG. 7, the terminal 3 has an input unit 90, an output unit 91, a communication unit 92, a CPU 93, a memory 94, and an HDD 95 connected via a bus 96, and functions as a computer. The terminal 3 is also capable of inputting and outputting data to and from a computer-readable storage medium 97.

[0032] The input unit 90 is, for example, a keyboard and a mouse, etc. The output unit 91 is, for example, a display device such as a display.

[0033] The communication unit 92 is, for example, a communication interface that performs wireless communication.

[0034] The CPU 93 controls each component constituting the terminal 3 and performs predetermined processing, etc. The memory 94 and HDD 95 constitute the storage unit 32 described above that stores data, etc.

[0035] The storage medium 97 is capable of storing programs and the like that cause the terminal 3 to execute the functions of the terminal 3. The architecture that configures the terminal 3 is not limited to the example shown in FIG.

[0036] 1...wireless communication system, 2...base station, 3...terminal, 4...HAPS, 5...low-orbit satellite (relay device), 6...geostationary satellite, 31...communication unit, 32...storage unit, 33...estimation unit, 34...control unit, 90...input unit, 91...output unit, 92...communication unit, 93...CPU, 94...memory, 95...HDD, 96...bus, 97...storage medium, 310...receiving unit, 312...transmitting unit

Claims

1. A wireless communication system having a terminal and a relay device that transmits beacon signals and data signals with highly periodic and reproducible timing while moving, wherein the terminal has: a communication unit that receives the beacon signals transmitted by the relay device; a memory unit that stores the reception time and reception strength of the beacon signals received by the communication unit; an estimation unit that estimates the timing when the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit; and a control unit that controls the communication unit to start transmitting and receiving a data signal to and from the relay device at the timing estimated by the estimation unit.

2. The wireless communication system according to claim 1, wherein the control unit, when controlling the communication unit to start transmitting and receiving a data signal with the relay device, controls the communication unit to receive again a beacon signal transmitted by the relay device after a predetermined period of time has elapsed.

3. The wireless communication system according to claim 1 or 2, wherein the relay device is a low-earth orbit satellite.

4. A terminal that wirelessly communicates with a relay device that transmits beacon signals and data signals with highly periodic and reproducible timing while moving, the terminal having a communication unit that receives the beacon signals transmitted by the relay device, a memory unit that stores the reception time and reception strength of the beacon signals received by the communication unit, an estimation unit that estimates the timing when the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit, and a control unit that controls the communication unit to start transmitting and receiving data signals with the relay device at the timing estimated by the estimation unit.

5. The terminal according to claim 4, wherein the control unit, when controlling the communication unit to start transmitting and receiving a data signal with the relay device, controls the communication unit to receive again a beacon signal transmitted by the relay device after a predetermined period of time has elapsed.

6. A wireless communication method in which a terminal communicates wirelessly with a relay device that transmits beacon signals and data signals at highly periodic and reproducible timing while moving, the wireless communication method comprising: a receiving step of receiving a beacon signal transmitted by the relay device; a storage step of storing the reception time and reception strength of the beacon signal received by the receiving step; an estimation step of estimating the timing at which the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored by the storage step; and a control step of controlling the relay device to start transmitting and receiving a data signal at the timing estimated by the estimation step.

7. The wireless communication method according to claim 6, characterized in that in the control step, when control is performed to start transmission and reception of a data signal with the relay device, control is performed so that the receiving step is performed again after a predetermined period has elapsed.

8. A wireless communication program executed by a terminal that wirelessly communicates with a relay device that transmits beacon signals and data signals with highly periodic and reproducible timing while moving, the wireless communication program causing a computer to function as each part of the terminal having: a communication unit that receives the beacon signal transmitted by the relay device; a memory unit that stores the reception time and reception strength of the beacon signal received by the communication unit; an estimation unit that estimates the timing when the relay device will next transmit a beacon signal and a data signal based on the reception time and reception strength stored in the memory unit; and a control unit that controls the communication unit to start transmitting and receiving data signals with the relay device at the timing estimated by the estimation unit.

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