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 first wireless terminal accommodated in the base station, and a second reflection angle when a second electromagnetic wave incident on the reflection section at the incident angle is reflected to a second wireless terminal not accommodated in the base station. The wireless communication system calculates a second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle, and determines whether the second electromagnetic wave of the calculated second wavelength can be used by the wireless communication system. When it is determined that it can be used, the wireless communication system performs control to assign the second electromagnetic wave of the calculated second wavelength to an electromagnetic wave which the second wireless terminal uses for wireless communication with the base station.SELECTED DRAWING: Figure 4

Description

[[Technical Field]]

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

[0002] Conventionally, a repeater device called a RIS (Reconfigurable Intelligent Surface) reflector, which can electrically change element characteristics and dynamically control the reflection characteristics of electromagnetic waves to relay electromagnetic waves (radio waves) used in radio communication, has been 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 publicly known (see, for example, Non-Patent Document 1). [[Prior Art Literature]] [[Non-Patent Literature]]

[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 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[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 communicate wirelessly via the reflecting section, wherein 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 first wireless terminal housed by the base station, and the second electromagnetic wave incident to the reflecting section at the incident angle is reflected to a second wireless terminal not housed by the base station. The system is characterized by comprising: an acquisition unit that acquires information indicating the second reflection angle in the case of; a wavelength calculation unit that calculates the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle; a determination unit that determines whether or not the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit is available for use in the wireless communication system; and a control unit that, if the determination unit determines that it is available, controls the allocation of the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit to the electromagnetic wave used by the second wireless terminal for wireless communication with the base station.

[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 direction of reflection of electromagnetic waves being controllable 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 first wireless terminal accommodated by the base station, and the second reflection angle when a second electromagnetic wave incident on the reflecting section at the incident angle is reflected to a second wireless terminal not accommodated by the base station; a wavelength calculation unit that calculates the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle; a determination unit that determines whether the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit is usable for wireless communication with the second wireless terminal; and a control unit that, if the determination unit determines that it is usable, controls the allocation of the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit to the electromagnetic wave used for wireless communication with the second wireless terminal.

[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 wireless communication system comprising a base station and a wireless terminal performs wireless communication via the reflecting portion, the first wavelength and incidence angle of a first electromagnetic wave incident from the base station to the reflecting portion, the first reflection angle at which the reflecting portion reflects the first electromagnetic wave to a first wireless terminal accommodated by the base station, and the second electromagnetic wave incident to the reflecting portion at the incidence angle is reflected to a second wireless terminal not accommodated by the base station. The system is characterized by including an acquisition step of acquiring information indicating the second reflection angle in the case of a second reflection angle; a wavelength calculation step of calculating the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle; a determination step of determining whether the second electromagnetic wave of the second wavelength calculated in the wavelength calculation step is usable in the wireless communication system; and a control step of performing control to allocate the second electromagnetic wave of the second wavelength calculated in the wavelength calculation step to the electromagnetic wave used by the second wireless terminal for wireless communication with the base station, if it is determined in the determination step that it is usable. [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 illustrating an example of a wireless communication system in operation. [Figure 8] This figure shows an example of a base station hardware configuration according to one embodiment. [Modes for carrying out the invention]

[0013] First, the outline of the present invention will be explained using a schematic diagram. Figure 1 is a schematic diagram showing the outline of the present invention. Even if the phase shift amount for controlling the reflection direction of electromagnetic waves is the same, if the frequencies of the incident electromagnetic waves are different, the electromagnetic waves will be reflected in different directions.

[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 RIS10, the RIS10 reflects the electromagnetic waves in different directions. The present invention makes it possible to accommodate multiple wireless terminals 101, 102 by utilizing the fact that even if the phase shift amount set in the RIS10 is the same, a shift in the reflection direction occurs when the frequencies (wavelengths) are different, as shown in Figure 1.

[0015] Figure 2 is a diagram illustrating the outline of the present invention in more detail. The present invention makes it possible to determine which frequency can accommodate the wireless terminal 102 when the phase shift amount set in RIS 10 is the same, RIS 10 has already accommodated the wireless terminal 101, and the position of the newly accommodated wireless terminal 102 (reflection angle to wireless terminal 102) is fixed.

[0016] For example, the wireless communication system according to the present invention obtains the spacing d of the multiple reflecting elements 100 provided by RIS10, the common incident angle θ with respect to RIS10, the reflection angle θ1 of the first frequency (first wavelength) λ1, and the reflection angle θ2, and calculates the second frequency (second wavelength) λ2.

[0017] For example, the wireless communication system according to the present invention specifies the wavelength λ2 using the incident angle θ, the reflection angle θ1, the wavelength λ1, and the reflection angle θ2, and can newly accommodate a wireless terminal 102 if the wavelength λ2 is available for use in the wireless communication system.

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

[0019]

Mathematical Expression

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

[0021]

Mathematical Expression

[0022] Then, when electromagnetic waves of a different wavelength λ2 are 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 Expression

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

[0025]

Mathematical Expression

[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 wavelength calculation unit 23, a determination unit 24, and a communication unit 25. 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 of the RIS 3, which is equipped with multiple reflective elements.

[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 allocation of the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit 23 to the electromagnetic wave used by the second wireless terminal for wireless communication with the base station, when the determination unit 24 determines that the second electromagnetic wave is available.

[0039] The acquisition unit 22 acquires information indicating the first wavelength λ1 and incidence angle θ of the first electromagnetic wave incident from the base station 2 to the reflector unit 34, the first reflection angle θ1 at which the reflector unit 34 reflects the first electromagnetic wave to a first wireless terminal (e.g., wireless terminal 4-1) that the base station 2 accommodates, and the second reflection angle θ2 at which the second electromagnetic wave incident to the reflector unit 34 at incidence angle θ is reflected to a second wireless terminal (e.g., wireless terminal 4-2) that the base station 2 does not accommodate.

[0040] The wavelength calculation unit 23 calculates the second wavelength λ2 of the second electromagnetic wave based on the first wavelength λ1, the incident angle θ, the first reflection angle θ1, and the second reflection angle θ2.

[0041] The determination unit 24 determines whether the second electromagnetic wave with the second wavelength λ2 calculated by the wavelength calculation unit 23 is available for use in the wireless communication system 1. For example, the determination unit 24 determines whether the second electromagnetic wave with the second wavelength λ2 calculated by the wavelength calculation unit 23 is available for use in the wireless communication system 1 by determining whether it is included in the multiple channels available in the wireless communication system 1 and whether it is unused.

[0042] The communication unit 25 performs wireless communication with the RIS 3. For example, the communication unit 25 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, an example of the operation of the wireless communication system 1 will be described. Figure 7 is a flowchart of an example of the 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 reflection angle information (reflection angle θ2) 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 wavelength λ2 using equation (4) above.

[0051] In step 108 (S108), base station 2 checks whether the wavelength λ2 is included in the frequency band available to base station 2 and wireless terminal 4 of the wireless communication system 1 and whether it has already been allocated, and determines whether the wavelength λ2 is newly available. If the wavelength λ2 is available (S108: Yes), base station 2 proceeds to process S110, and if it is not available (S108: No), it returns to process S100.

[0052] In step 110 (S110), the base station 2 assigns wavelength λ2 to the unacquired wireless terminal 4, making the wireless terminal 4 an accepted wireless terminal, and returns to the process of S100.

[0053] In this way, the wireless communication system 1 can reflect multiple electromagnetic waves, enabling the wireless communication system to efficiently accommodate multiple wireless terminals.

[0054] 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.

[0055] 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.

[0056] Figure 8 shows an example of the hardware configuration of a base station 2 according to one embodiment. As shown in Figure 8, 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.

[0057] 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.

[0058] 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.

[0059] 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 8. [Explanation of symbols]

[0060] 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... Wavelength calculation unit, 24... Judgment unit, 25... 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 incident 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 first wireless terminal housed by the base station, and the second reflection angle when the second electromagnetic wave incident at the incident angle to the reflecting unit is reflected to a second wireless terminal not housed by the base station. A wavelength calculation unit that calculates the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle, A determination unit determines whether the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit is usable in the wireless communication system, When the determination unit determines that it is available, the control unit controls the allocation of the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit to the electromagnetic wave used by the second wireless terminal for wireless communication with the base station. A wireless communication system characterized by having the following features.

2. The determination unit, The determination of whether or not the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit is included among the multiple channels available in the wireless communication system is made by determining whether or not it is unused. 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 a first wireless terminal housed by the base station, and the second reflection angle when the second electromagnetic wave incident on the reflecting unit at the incident angle is reflected to a second wireless terminal not housed by the base station. A wavelength calculation unit that calculates the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle, A determination unit determines whether the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit can be used for wireless communication with the second wireless terminal, When the determination unit determines that it is available, the control unit performs control to allocate the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit to the electromagnetic wave used for wireless communication with the second wireless terminal. A base station characterized by having the following features.

4. The determination unit, The determination of whether or not the second electromagnetic wave of the second wavelength calculated by the wavelength calculation unit is available among the multiple channels available for wireless communication with the second wireless terminal is made by determining whether or not it is unused. The base station according to claim 3, characterized by the following:

5. In a wireless communication method in which a wireless communication system comprising a base station and a wireless terminal performs wireless communication via a reflecting section, the direction in which the reflecting section reflects electromagnetic waves can be controlled by controlling the phase shift amount of the reflecting section comprising 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 a first wireless terminal housed by the base station, and the second reflection angle when the second electromagnetic wave incident to the reflecting unit at the incidence angle is reflected to a second wireless terminal not housed by the base station. A wavelength calculation step for calculating the second wavelength of the second electromagnetic wave based on the first wavelength, the incident angle, the first reflection angle, and the second reflection angle, A determination step of determining whether the second electromagnetic wave of the second wavelength calculated by the wavelength calculation step is usable in the wireless communication system, If the determination step determines that it is usable, a control step is performed to control the second electromagnetic wave of the second wavelength calculated in the wavelength calculation step to be used by the second wireless terminal for wireless communication with the base station. A wireless communication method characterized by including

6. In the aforementioned determination step, The determination of whether or not the second electromagnetic wave of the second wavelength calculated by the wavelength calculation step is included among the multiple channels available in the wireless communication system is made by determining whether or not it is unused. 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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