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

Abstract

To make it possible for a wireless communication system to efficiently accommodate a plurality of wireless terminals by reflecting a plurality of electromagnetic waves.SOLUTION: A wireless communication system obtains information indicating a first wavelength and an incident angle of a first electromagnetic wave that is incident on a reflection section from a base station, a first reflection angle at which the reflection section reflects the first electromagnetic wave to a wireless terminal accommodated in the base station, and a second wavelength of a second electromagnetic wave that can be used for wireless communication by other wireless terminals not accommodated in the base station. The wireless communication system calculates a second reflection angle at which the reflection section reflects the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength, and controls the base station to accommodate another wireless terminal that is located closest to the direction of the calculated second reflection angle and not accommodated by the base station by using the second electromagnetic wave.SELECTED DRAWING: Figure 4

Description

[[Technical Field]]

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

[0002] Conventionally, a repeater device called a RIS (Reconfigurable Intelligent Surface) reflector, which electrically changes element characteristics to dynamically control the reflection characteristics of electromagnetic waves for relaying electromagnetic waves (radio waves) used in wireless communication, is known.

[0003] Further, a technique of controlling the direction in which a RIS reflector reflects electromagnetic waves by performing phase control on an incident wave of a specific frequency is known (see, for example, Non-Patent Document 1). In addition, Non-Patent Document 2 discloses a method for expanding a reflected beam width. [[Prior Art Documents]] [[Non-Patent Documents]]

[0004] [[Non-Patent Document 1]] Yashuai Cao, Tiejun Lv and Wei Ni, "Intelligent Reflecting Surface Aided Multi-User mmWave Communications for Coverage Enhancement", 2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications: Track 1 - PHY and Fundamentals, 2020 [[Non-Patent Document 2]] Corentin Fonteneau, Matthieu Crussiere, Bruno Jahany, “A Systematic Beam Broadening Method for Large Phased Arrays”, 2021 Joint European Conference on Networks and Communications & 6G Summit (EuCNC / 6G Summit): Physical Layer and Fundamentals (PHY) [Overview of the project] [Problems that the invention aims to solve]

[0005] When using an RIS reflector to reflect electromagnetic waves, even if the phase controlled relative to the RIS reflector is the same, if the frequency of the incident electromagnetic wave is different, the direction of reflection will also be different. Furthermore, when high-frequency bands are used for wireless communication, the bandwidth is generally wider. And even with wireless communication systems of the same standard, if the channels are different, the frequencies will differ significantly, and the direction of reflection by the same RIS reflector will also differ.

[0006] Therefore, conventional base stations had to operate by switching the phase control of the RIS reflector directed towards a single wireless terminal at minute intervals, which sometimes made it difficult to accommodate multiple wireless terminals simultaneously.

[0007] The present invention has been made in view of the above-mentioned problems, and aims to provide a wireless communication system, base station, wireless communication method, and wireless communication program that enable a wireless communication system to efficiently accommodate multiple wireless terminals by reflecting multiple electromagnetic waves. [Means for solving the problem]

[0008] A wireless communication system according to one aspect of the present invention is a wireless communication system in which a reflecting section comprising a plurality of reflecting elements can control the direction in which the reflecting section reflects electromagnetic waves by controlling the amount of phase shift of the reflecting section, and a base station and a wireless terminal perform wireless communication via the reflecting section, characterized in that it comprises: an acquisition unit that acquires information indicating the first wavelength and incident angle of a first electromagnetic wave incident from the base station to the reflecting section, the first reflection angle at which the reflecting section reflects the first electromagnetic wave to a wireless terminal accommodated by the base station, and the second wavelength of a second electromagnetic wave that can be used for wireless communication by other wireless terminals not accommodated by the base station; a reflection angle calculation unit that calculates the second reflection angle at which the reflecting section reflects the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength; and a control unit that controls the base station to accommodate other wireless terminals not accommodated by the base station, which are located closest to the direction of the second reflection angle calculated by the reflection angle calculation unit, using the second electromagnetic wave.

[0009] Furthermore, a base station according to one aspect of the present invention is a base station that performs wireless communication with a wireless terminal via a reflecting section equipped with a plurality of reflecting elements, the reflecting section being able to control the direction of reflection of electromagnetic waves by controlling the amount of phase shift, and is characterized by comprising: an acquisition unit that acquires information indicating the first wavelength and incident angle of a first electromagnetic wave incident on the reflecting section, the first reflection angle at which the reflecting section reflects the first electromagnetic wave to a wireless terminal accommodated by the base station, and the second wavelength of a second electromagnetic wave that can be used for wireless communication by other wireless terminals not accommodated by the base station; a reflection angle calculation unit that calculates the second reflection angle at which the reflecting section reflects the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength; and a control unit that controls the base station to accommodate other wireless terminals not accommodated by the base station, which are located closest to the direction of the second reflection angle calculated by the reflection angle calculation unit, using the second electromagnetic wave.

[0010] Furthermore, in a wireless communication method according to one aspect of the present invention, the direction in which a reflecting portion reflects electromagnetic waves can be controlled by controlling the phase shift amount of a reflecting portion comprising a plurality of reflecting elements, and in a wireless communication method in which a base station and a wireless terminal communicate via the reflecting portion, the method includes an acquisition step of acquiring information indicating a first wavelength and incident angle of a first electromagnetic wave incident from the base station to the reflecting portion, a first reflection angle in which the reflecting portion reflects the first electromagnetic wave to a wireless terminal accommodated by the base station, and a second wavelength of a second electromagnetic wave that can be used for wireless communication by other wireless terminals not accommodated by the base station; a reflection angle calculation step of calculating a second reflection angle in which the reflecting portion reflects the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength; and a control step of controlling the base station to accommodate other wireless terminals not accommodated by the base station, which are located closest to the direction of the second reflection angle calculated in the reflection angle calculation step, using the second electromagnetic wave. [Effects of the Invention]

[0011] According to the present invention, it is possible to reflect multiple electromagnetic waves to enable a wireless communication system to efficiently accommodate multiple wireless terminals. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically illustrates the outline of the present invention. [Figure 2] This figure provides a more specific overview of the present invention. [Figure 3] This figure shows an example configuration of a wireless communication system according to one embodiment. [Figure 4] This is a functional block diagram illustrating the functions of a base station and a RIS (Routing System). [Figure 5] This diagram illustrates the information stored in the RIS information storage unit. [Figure 6] This diagram illustrates the information stored in the wireless terminal information storage unit. [Figure 7] A flowchart showing the first operational example of a wireless communication system. [Figure 8] It is a flowchart illustrating a second operation example of a wireless communication system. [Figure 9] It is a diagram illustrating a hardware configuration example of a base station according to an embodiment. MODE FOR CARRYING OUT THE INVENTION

[0013] First, the outline of the present invention will be described with reference to schematic diagrams. Figure 1 is a diagram schematically illustrating the outline of the present invention. Even if the amount of phase shift for controlling the reflection direction of electromagnetic waves is the same for a RIS (RIS reflector) 10, if the frequencies of incident electromagnetic waves are different, the electromagnetic waves will be reflected in different directions respectively.

[0014] For example, when an electromagnetic wave of a first frequency and an electromagnetic wave of a second frequency different from the first frequency are incident on the RIS 10, the RIS 10 reflects the electromagnetic waves in different directions respectively. The present invention makes it possible to accommodate a plurality of wireless terminals 101 and 102 by utilizing the fact that even if the same phase shift amount is set for the RIS 10, a deviation in reflection direction occurs when the frequency (wavelength) is different as shown in Figure 1.

[0015] Figure 2 is a diagram more specifically illustrating the outline of the present invention. The present invention enables determination of which reflection angle can accommodate a newly accommodated wireless terminal 102 when the phase shift amount set for the RIS 10 is the same, the RIS 10 already accommodates the wireless terminal 101, and the available frequency of the newly accommodated wireless terminal 102 (the wavelength of electromagnetic waves available to the wireless terminal 102) is fixed.

[0016] For example, the wireless communication system according to the present invention obtains the spacing d between a plurality of reflecting elements 100 included in the RIS 10, the common incident angle θ with respect to the RIS 10, the reflection angle θ1 of a first frequency (first wavelength) λ1, and a second frequency (second wavelength) λ2, and calculates the reflection angle θ2.

[0017] For example, the wireless communication system according to the present invention can specify the reflection angle θ2 using the incident angle θ, the reflection angle θ1, the wavelength λ1, and the wavelength λ2, and newly accommodate the wireless terminal 102 located in the direction of the reflection angle θ2.

[0018] Specifically, in the wireless communication system, for example, when the spacing d between a plurality of reflecting elements included in the RIS 10, the wavelength λ1, and the incident angle θ are given, the reflection angle θ1 is calculated by the following formula (1).

[0019] [Mathematical formula]

[0020] Note that the phase shift amount θr is calculated by the following formula (2).

[0021] [Mathematical formula]

[0022] Then, when an electromagnetic wave with a different wavelength λ2 is incident on the RIS 10 to which the phase shift amount θr has been set, the reflection angle θ2 is calculated by the following formula (3).

[0023] [Mathematical formula]

[0024] Then, when the wavelength λ1, the incident angle θ, the reflection angle θ1, and the reflection angle θ2 are given, the wavelength λ2 is calculated by the following formula (4).

[0025] [Mathematical formula]

[0026] Next, a wireless communication system 1 according to one embodiment will be described. Figure 3 is a diagram showing an example of the configuration of a wireless communication system 1 according to one embodiment. As shown in Figure 3, the wireless communication system 1 is configured such that, for example, a base station 2 can accommodate a plurality of wireless terminals 4-1 to 4-4 via, for example, RIS3-1 and 3-2.

[0027] The wireless communication system 1 has a function to control the direction in which the reflecting part reflects electromagnetic waves by controlling the amount of phase shift of the reflecting part, which is equipped with multiple reflecting elements. The wireless communication system 1 then communicates wirelessly between the base station 2 and multiple wireless terminals 4 via the reflecting part.

[0028] Note that if you are not specifying which of the multiple configurations, such as RIS3-1 or RIS3-2, you can simply abbreviate it as RIS3.

[0029] Next, we will explain a specific configuration example of base station 2 and RIS3 using Figure 4. Figure 4 is a functional block diagram illustrating the functions of base station 2 and RIS3.

[0030] For example, base station 2 has a memory unit 20, a control unit 21, an acquisition unit 22, a reflection angle calculation unit 23, and a communication unit 24. Base station 2 also has the function of simultaneously transmitting electromagnetic waves of different wavelengths to each of the multiple wireless terminals 4. Furthermore, base station 2 has the function of controlling the direction in which the RIS 3 reflects electromagnetic waves by controlling the phase shift amount of the reflection unit 34, which has multiple reflective elements in the RIS 3.

[0031] Furthermore, RIS3 includes a communication unit 30, a phase shift amount control unit 32, and a reflection unit 34. The functions of RIS3 will be described later.

[0032] First, let's explain the functions of base station 2. The memory unit 20 includes, for example, an RIS information memory unit 200 and a wireless terminal information memory unit 202, and stores the information necessary for base station 2 to communicate wirelessly with multiple wireless terminals 4 via RIS 3.

[0033] Figure 5 is a diagram illustrating the information stored by the RIS information storage unit 200. As shown in Figure 5, the RIS information storage unit 200 stores information such as the location information of the RIS3, the incidence angle of the signal (electromagnetic wave) from the base station 2 to the RIS3, the wireless terminal 4 connected via the RIS3, and the control reflection angle to the RIS3.

[0034] Here, location information may be acquired, for example, when RIS3 is installed, or it may be acquired by RIS3 itself using GPS or the like, or it may be acquired via control signals or the like.

[0035] The incidence angle of the signal from base station 2 may be calculated from the base station location information and RIS3 location information known at the time of installation.

[0036] The wireless terminal 4 connected via RIS3, and the control reflection angle relative to RIS3, may be determined from control signals from RIS3, etc.

[0037] Figure 6 is a diagram illustrating the information stored by the wireless terminal information storage unit 202. As shown in Figure 6, the wireless terminal information storage unit 202 stores information such as the location information of the wireless terminal 4, the wavelength of electromagnetic waves usable by the wireless terminal 4, the RIS3 that houses the wireless terminal 4, and the reflection angle as seen from the RIS3 that houses the wireless terminal 4.

[0038] The control unit 21 (Figure 4) controls each component of the base station 2. For example, as will be described later, the control unit 21 has a function to control the base station 2 to use the second electromagnetic wave to accommodate other wireless terminals that are located closest to the direction of the second reflection angle calculated by the reflection angle calculation unit 23 and are not currently accommodated by the base station 2.

[0039] Furthermore, the control unit 21 may also have a function to correct the phase shift amount with respect to the reflector 34 so that, if there are no other wireless terminals not connected to the base station 2 in the direction of the second reflection angle calculated by the reflection angle calculation unit 23 (described later), the sum of the throughput of the wireless terminals connected to the base station 2 and other wireless terminals not connected to the base station 2 is maximized.

[0040] The acquisition unit 22 acquires information indicating the first wavelength and incidence angle of the first electromagnetic wave incident from the base station 2 to the reflector 34, the first reflection angle at which the reflector 34 reflects the first electromagnetic wave to the wireless terminals housed in the base station 2, and the second wavelength of the second electromagnetic wave that can be used for wireless communication by other wireless terminals not housed in the base station 2.

[0041] The reflection angle calculation unit 23 calculates the second reflection angle θ2 at which the reflection unit 34 reflects the second electromagnetic wave, based on the first wavelength λ1, the incident angle θ, the first reflection angle θ1, and the second wavelength λ2.

[0042] The communication unit 24 performs wireless communication with the RIS 3. For example, the communication unit 24 transmits the results processed by the base station 2 to the RIS 3, which is equipped with a reflector 34.

[0043] Next, the functions of RIS3 (Figure 4) will be described. As mentioned above, RIS3 has a communication unit 30, a phase shift amount control unit 32, and a reflection unit 34.

[0044] The communication unit 30 performs wireless communication with the base station 2. For example, the communication unit 30 receives information transmitted by the communication unit 26.

[0045] The phase shift control unit 32 controls the phase shift amount of the reflector 34 based on the phase shift amount calculated by the base station 2.

[0046] As described above, the reflective section 34 comprises multiple reflective elements and changes the reflection direction of the incident electromagnetic wave based on a set phase shift amount.

[0047] Next, a first example of operation of the wireless communication system 1 will be described. Figure 7 is a flowchart of the first example of operation of the wireless communication system 1. As shown in Figure 7, in step 100 (S100), for example, base station 2 determines whether or not there are any unconnected wireless terminals 4. If there are any unconnected wireless terminals 4 (S100: Yes), base station 2 proceeds to process S102, and if there are no unconnected wireless terminals 4 (S100: No), the process ends.

[0048] In step 102 (S102), the base station 2 acquires information, for example, the incident angle θ, first wavelength λ1, and first reflection angle θ1 of the electromagnetic wave from the RIS information storage unit 200 to the RIS3.

[0049] In step 104 (S104), the base station 2 selects, for example, one unconnected wireless terminal 4 and obtains the wavelength information (wavelength λ2) of the selected wireless terminal 4 from the wireless terminal information storage unit 202.

[0050] In step 106 (S106), base station 2 calculates the accommodable reflection angle θ2 using equation (3) above.

[0051] In step 108 (S108), base station 2 determines whether or not there is an unacquired wireless terminal in the direction of reflection angle θ2. If base station 2 determines that there is an unacquired wireless terminal in the direction of reflection angle θ2 (S108: Yes), it proceeds to process S112. If base station 2 determines that there is no unacquired wireless terminal in the direction of reflection angle θ2 (S108: No), it proceeds to process S110.

[0052] In step 110 (S110), base station 2 corrects the phase shift amount θr relative to RIS3 using the following equation (5) and corrects the beam width (see Non-Patent Document 2).

[0053]

number

[0054] Specifically, base station 2 adjusts the beamwidth coefficient B2 according to equation (5) above, so that the sum of the throughput of already accommodated wireless terminals and newly selected unaccommodated wireless terminals is maximized, using the multiple reflective elements x, reflection direction coefficient B1, beamwidth coefficient B2, and number of reflective elements L provided by the reflector 34, and corrects the phase shift amount.

[0055] In step 112 (S112), base station 2 designates an unconnected wireless terminal as a connected wireless terminal and returns to the process of S100.

[0056] Next, a second example of operation of the wireless communication system 1 will be described. Figure 8 is a flowchart of the second example of operation of the wireless communication system 1. As shown in Figure 8, in step 200 (S200), for example, base station 2 determines whether or not there are any unconnected wireless terminals 4. If there are any unconnected wireless terminals 4 (S200: Yes), base station 2 proceeds to processing S202, and if there are no unconnected wireless terminals 4 (S200: No), the process ends.

[0057] In step 202 (S202), the base station 2 acquires information, for example, the incident angle θ, first wavelength λ1, and first reflection angle θ1 of the electromagnetic wave from the RIS information storage unit 200 to the RIS3.

[0058] In step 204 (S204), the base station 2 calculates the accommodable reflection angle θx for all unaccommodated wireless terminals 4 using the following equation (6) and stores it in the wireless terminal information storage unit 202.

[0059]

number

[0060] In step 206 (S206), base station 2 selects the wireless terminal whose positional relationship to the accommodable reflection angle θx is closest.

[0061] In step 208 (S208), base station 2 corrects the phase shift amount θr relative to RIS3 using equation (5) above, corrects the beam width, and returns to processing in S200.

[0062] In this way, the wireless communication system 1 can reflect multiple electromagnetic waves, enabling the wireless communication system to efficiently accommodate multiple wireless terminals.

[0063] Furthermore, each function of base station 2 and RIS3 may be partially or entirely comprised of hardware such as PLDs (Programmable Logic Devices) or FPGAs (Field Programmable Gate Arrays), or it may be comprised of a program executed by a processor such as a CPU.

[0064] For example, the wireless communication system according to the present invention can be implemented using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0065] Figure 9 shows an example of the hardware configuration of a base station 2 according to one embodiment. As shown in Figure 9, for example, the base station 2 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 base station 2 is also configured to be able to input and output data to and from a computer-readable storage medium 57.

[0066] 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. The communication unit 52 is, for example, a wireless network interface.

[0067] The CPU 53 controls each component of the base station 2 and performs predetermined processing. The memory 54 and HDD 55 are storage units that store data, etc.

[0068] The storage medium 57 is capable of storing programs and the like that which cause the base station 2 to perform its functions. Note that the architecture of the base station 2 and RIS 3 is not limited to the example shown in Figure 9. [Explanation of Symbols]

[0069] 1... Wireless communication system, 2... Base station, 3-1, 3-2, 10... RIS, 4-1~4-4, 101, 102... Wireless terminal, 20... Memory unit, 21... Control unit, 22... Acquisition unit, 23... Reflection angle calculation unit, 24... Communication unit, 30... Communication unit, 32... Phase shift amount control unit, 34... Reflection unit, 50... Input unit, 51... Output unit, 52... Communication unit, 53... CPU, 54... Memory, 55... HDD, 56... Bus, 57... Storage medium, 100... Reflecting element, 200... RIS information storage unit, 202... Wireless terminal information storage unit

Claims

1. In a wireless communication system in which a base station and a wireless terminal communicate wirelessly via a reflecting section, the direction in which the reflecting section reflects electromagnetic waves can be controlled by controlling the amount of phase shift of the reflecting section, An acquisition unit that acquires information indicating the first wavelength and incidence angle of the first electromagnetic wave incident from the base station to the reflecting unit, the first reflection angle at which the reflecting unit reflects the first electromagnetic wave to a wireless terminal housed in the base station, and the second wavelength of the second electromagnetic wave that can be used for wireless communication by other wireless terminals not housed in the base station. A reflection angle calculation unit calculates a second reflection angle at which the reflecting unit reflects the second electromagnetic wave, based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength. A control unit located closest to the direction of the second reflection angle calculated by the reflection angle calculation unit controls the base station to accommodate other wireless terminals not accommodated by the base station using the second electromagnetic wave. A wireless communication system characterized by having the following features.

2. The control unit, If there are no other wireless terminals not connected to the base station in the direction of the second reflection angle calculated by the reflection angle calculation unit, the phase shift amount for the reflection unit is corrected so that the sum of the throughput of the wireless terminals connected to the base station and the other wireless terminals not connected to the base station is maximized. The wireless communication system according to claim 1, characterized by the following:

3. In a base station that performs wireless communication with a wireless terminal via a reflector equipped with multiple reflecting elements, the direction of reflection of electromagnetic waves can be controlled by controlling the amount of phase shift, An acquisition unit that acquires information indicating the first wavelength and incident angle of the first electromagnetic wave incident on the reflecting unit, the first reflection angle at which the reflecting unit reflects the first electromagnetic wave to the wireless terminals housed in the base station, and the second wavelength of the second electromagnetic wave that can be used for wireless communication by other wireless terminals not housed in the base station. A reflection angle calculation unit calculates a second reflection angle at which the reflecting unit reflects the second electromagnetic wave, based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength. A control unit located closest to the direction of the second reflection angle calculated by the reflection angle calculation unit controls the base station to accommodate other wireless terminals not currently accommodated by the base station using the second electromagnetic wave. A base station characterized by having the following features.

4. The control unit, If there are no other wireless terminals not connected to the base station in the direction of the second reflection angle calculated by the reflection angle calculation unit, the phase shift amount for the reflector is corrected so that the sum of the throughput of the wireless terminals connected to the base station and the other wireless terminals not connected to the base station is maximized. The base station according to claim 3, characterized by the following:

5. In a wireless communication method in which a base station and a wireless terminal perform wireless communication via a reflecting section, the direction in which the reflecting section reflects electromagnetic waves can be controlled by controlling the amount of phase shift of the reflecting section, the reflecting section comprises multiple reflecting elements, An acquisition step of acquiring information indicating the first wavelength and incidence angle of the first electromagnetic wave incident from the base station to the reflecting unit, the first reflection angle at which the reflecting unit reflects the first electromagnetic wave to the wireless terminals housed in the base station, and the second wavelength of the second electromagnetic wave that can be used for wireless communication by other wireless terminals not housed in the base station. A reflection angle calculation step, which calculates the second reflection angle at which the reflecting part reflects the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second wavelength, A control step which controls the base station to use the second electromagnetic wave to accommodate other wireless terminals that are located closest to the direction of the second reflection angle calculated in the reflection angle calculation step and are not currently accommodated by the base station. A wireless communication method characterized by including

6. In the control process described above, If there are no other wireless terminals not connected to the base station in the direction of the second reflection angle calculated by the reflection angle calculation step, the phase shift amount for the reflector is corrected so that the sum of the throughput of the wireless terminals connected to the base station and the other wireless terminals not connected to the base station is maximized. The wireless communication method according to claim 5, characterized by the above.

7. A wireless communication program for causing a computer to function as a component of the base station described in claim 3 or 4.

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