JP2023156537A - wireless communication system - Google Patents

Abstract

To provide a sustainable and robust network without degrading the characteristics of next-generation communications.SOLUTION: A wireless communication system includes: a UAV that functions as a relay station or a base station; a terminal that receives carrier waves via the UAV; and a window glass that includes an antenna that receives power based on electromagnetic waves, and wirelessly supplies power received by the antenna and stored power to other electrically operated devices including the UAV via the antenna.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to wireless communication systems.

5G, which is currently being operated as a wireless communication system, uses high-frequency carrier waves of several GHz to several tens of G, and it is expected that the next-generation 6G and 7G wireless communication systems will use even higher frequency carrier waves. be done. Furthermore, it is expected that the occupied bandwidth will become wider, from several hundred MHz to several GHz.

While 5G communication systems and next-generation communication systems can achieve high-capacity communication and low-latency characteristics, they have the problem that the physical phenomenon of radio wave propagation is that the propagation distance of radio waves is significantly reduced. In order to cope with the decrease in propagation distance, increasing the output of radio waves may be considered, but due to the effects of radio waves on the human body and restrictions such as the radio laws and EMC standards of each country, it is not possible to increase the output of radio waves indefinitely. Can not.

In order to make next-generation communication systems, including 5G, more sustainable and robust than conventional communication systems, there are the following problems and challenges.
(1) Since the carrier wave is a high frequency, the propagation distance is short due to the influence of physical propagation loss.
(2) Since the carrier wave is a high frequency, it is significantly affected by obstacles.
(3) In order to apply a communication network between terminals and base stations such as the one built with 4G LTE to 5G, 6G, etc., an unrealistic number of base stations must be installed in a city.

In order to solve such problems, a system has been proposed in which a relay station or a base station in a wireless communication system is configured by, for example, a UAV (Unmanned Aerial Vehicle) such as a drone (see, for example, Patent Document 1). By moving a drone that functions as a relay station or base station, the problem of radio wave propagation distance can be solved.

When a large number of terminals are connected to a UAV and requesting low-latency communication, there is a problem in which it becomes difficult to establish communication if the UAV is about to run out of charge. A possible example is described below in this proposal.

Japanese Patent Application Publication No. 2019-102872

In view of these problems, it is an object of the present invention to provide a sustainable and robust network without deteriorating the characteristics of next-generation communication such as propagation distance and communication time constraints.

In order to achieve the above object, a wireless communication system according to the present invention includes a UAV that functions as a relay station or a base station, a terminal that receives carrier waves via the UAV, and an antenna that receives power based on electromagnetic waves. and a window glass that wirelessly supplies power received by the antenna to other electrically operated devices including the UAV via the antenna.

According to the present invention, it is possible to provide a sustainable and robust network without deteriorating the characteristics of next-generation communication such as propagation distance and communication time constraints.

FIG. 2 is a schematic diagram illustrating problems with conventional wireless communication systems based on 4G, 5G, or the like. FIG. 2 is a schematic diagram illustrating problems with conventional wireless communication systems based on 4G, 5G, or the like. 1 is a schematic diagram illustrating the basic configuration of a wireless communication system according to an embodiment of the present invention. 1 is a schematic diagram illustrating the basic configuration of a wireless communication system according to an embodiment of the present invention. It is a schematic diagram explaining the flight range of UAV21. An example of antenna units ANT1 to ANT12 forming array antenna A or B, which are arranged on the window glass of a building, will be explained. FIG. 2 is a circuit diagram of array antenna A or B (antenna units: ANT1 to ANT12). An example of the configuration of an antenna unit disposed on one window glass will be described. A configuration example of a power storage circuit of an array antenna will be described. An example of further detailed structures of array antennas A and B is shown. FIG. 3 is a diagram simulating a multiband antenna pattern. 12 shows an example of band characteristics of the antenna circuit of FIG. 11.

This embodiment will be described below with reference to the accompanying drawings. In the accompanying drawings, functionally similar elements may be designated by the same number. Although the attached drawings show embodiments and implementation examples in accordance with the principles of the present disclosure, they are for the purpose of understanding the present disclosure, and should not be used to limit the present disclosure in any way. isn't it. The descriptions herein are merely typical examples and do not limit the scope of claims or applications of the present disclosure in any way.

Although the embodiments are described in sufficient detail for those skilled in the art to implement the present disclosure, other implementations and forms are possible without departing from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that it is possible to change the composition and structure and replace various elements. Therefore, the following description should not be interpreted as being limited to this.

Before describing the embodiments, problems with conventional wireless communication systems based on 4G, 5G, etc. will be described with reference to FIGS. 1 and 2.

In a 5G wireless communication system, when using wireless communication from a terminal located indoors (for example, house 6), it may not be possible to directly transmit radio waves from house 6 to base station 1 because the propagation distance of radio waves is short. obtain. In this case, for example, propagation paths 10 and 11 via a relay station installed on the roof of a nearby building 3 are secured, thereby making it possible to establish communication between the residence 6 and the base station 1. At this time, it can be assumed that the antennas of the relay stations on the rooftops of the house 6 and the building 3 are at fixed positions and do not move, and that the propagation path from the house 6 to the base station 1 is secured. I can do it.

On the other hand, mobile terminals such as smartphones and wearable devices, or wireless communication devices installed in cars, are carried by people (numerals 4 and 5) or cars, and therefore there is no communication between these devices and the base station 1. The propagation path between them changes over time. In that case, propagation paths 7, 8, 9, and 10 are secured by relay stations installed on the rooftops of buildings 2 and 3, and communication between those devices and base station 1 is thereby established. Ru. Note that the above communication is basically performed via the same route for both uplink and downlink.

If a mobile terminal, etc. is moved by a person or a car to an area that cannot be covered by base station 1, a hard/soft handover is performed and an appropriate relay station is connected to the new base station in the same way as above. A selection is made and communication is established. There are two methods for building a 5G system. One is local 5G (Private 5G), which constitutes a 5G system in a closed area, and the other is WAN 5G, which is often used for purposes other than corporate activities. WAN 5G, which is used on a daily basis, has an overwhelming number of terminals, network lines, users, applications, and market size compared to local 5G. The present invention is applicable not only to WAN 5G but also to local 5G, and is not limited by applications.

FIG. 2 is a diagram simulating a wireless section from a UE (User Equipment) to a gNB (base station) in a general 5G communication network, regardless of whether it is local 5G or WAN 5G. For example, if a communication terminal configured with local 5G or WAN 5G or a signal from area 13 with a network is transmitted to base station 1, or data from base station 1 is received in area 13, a building 12 may exist on the route connecting the base station 1 and the area 13. Signals transmitted from area 13 propagate through path 14 but are blocked by building 12 . Specifically, due to physical phenomena of radio waves such as reflection, scattering, absorption, etc. (numerals 15 and 16), power cannot be propagated to the base station 1, which is the receiving point.

However, with the current 5G, it is possible to improve the quality of communication using techniques such as beam forming and beam tracking. For example, as shown in FIG. 2, if communication is not possible on the transmission path 14, a propagation path 19 is established between the array antenna 17 installed on the roof of the building 12 and the area 13, so that the array antenna 17 performs beam tracking. and perform beamforming. Similarly, the array antenna 18 installed on the roof of the building 12 establishes a propagation path 20 between the array antenna 18 and the base station 1 by performing beam tracking and beam forming. By establishing these propagation paths 19 and 20, communication between base station 1 and area 13 is established. In other words, data from a device in the area 13 can be transmitted to the base station 1 located a distance d away via the array antennas 17 and 18 installed on the roof of the building 12.

In conventional wireless communication systems, the communication path design is fixed in a certain band, and the cell is designed with a margin in consideration of carrier frequency, device output level, spatial transmission loss, transmitting/receiving antenna gain, etc. I have been designing the base station layout. However, with regard to 5G and next-generation wireless communications, various other wireless protocols such as 4G band, 5G (Sub6 band (FR1)), 28GHz band (FR2), and LPWA (920MHz band) are bundled together and large-capacity lines are created. It will be transmitted to the core wireless protocol with It is becoming important to have software base stations that are functionally/physically distributed and dynamically move hardware devices, rather than fixed base stations or centralized ones. In the future, when the communication generation moves to 6G and beyond, the center frequency of the carrier wave will definitely increase, and the communication distance will be physically shortened. This reduction in propagation distance is in a trade-off relationship with improvement in communication speed.

Although the general concept of existing 5G wireless communication has been explained in the existing wireless communication system used in 5G, the frequency of carrier waves used in future wireless communication will be higher and the bandwidth will be wider. Therefore, when the frequency, band, antenna gain, antenna height, transmission power, reception sensitivity, directivity, propagation environment, etc. are the same, the free space communication distance and propagation loss L of radio waves are calculated by the following formula [Equation 1] It can be expressed generally by

[Number 1]
L=(4πd/λ) ²
however,
L: Free space propagation loss d: Communication distance λ: Wavelength

If the communication distance doubles, the loss will quadruple, or the transmission power will be 1/4. Considering the power ratio, this is a 6 dB reduction. If the carrier frequency used for communication doubles, the loss will quadruple, so compared to 4G LTE, the frequency used for communication using the FR2 band (28GHz band) such as 5G and subsequent next generation communication will be lower. As the communication distance becomes further shortened, physical phenomena such as reflection, scattering, absorption, and interference will cause adverse effects, and the stability of the network will be significantly impaired. Due to multipath fading, the optimal transmission and reception points constantly change over time, so the higher the frequency handled, the shorter the communication distance.

FIG. 3 is a schematic diagram illustrating the basic configuration of a wireless communication system according to an embodiment of the present invention, proposed in view of this point of view. Components that are the same as those in FIG. 2 are denoted by the same reference numerals in FIG. 3, so redundant explanation will be omitted.

The wireless communication system of this embodiment includes a drone or UAV 21 that functions as a relay station. The UAV 21 has functions corresponding to the array antennas (repeater) 17 and 18 in FIG. 2 and a base station function, and is configured to be able to fly in the air. The number of UAVs 21 is not limited to one, and several dozen UAVs may be arranged within a predetermined range as needed, and the number of UAVs 21 is not limited to a specific number.

The UAV 21 in FIG. 3 transmits high-frequency carrier wave signals used for 5G or next-generation wireless communications, respectively, regarding transmission signals to and reception signals from area 13 that have terminals operating under local 5G or WAN 5G network conditions. A contract is established through propagation paths 23, 24, 25, and 26 using . At that time, in order to establish communication with the UAV 21, the terminal within the area 13 performs beam tracking and beam forming 27, 28 before communication, confirms the positions of the terminal and the UAV 21, and performs RSSI, S/N, Carrier Sense. Share information related to communication quality such as level, packet error rate (PER), communication route, delay time, etc. FIG. 3 shows an example of the configured wireless network, and there is no restriction on the number of UAVs such as drones used in the actual configuration.

Similarly, in order to establish communication between the UAV 21 and the base station 1, beam tracking and beam forming 29, 30 are performed before communication to confirm whether or not they can communicate with each other, and check the communication quality, communication route, delay time, etc. etc. is shared between the UAV 21 and the base station 1.

At this time, the position of the UAV 21 is not fixed like the array antennas (repeater) 17 and 18 in FIG. 2, but the UAV 21 automatically and dynamically selects its position and flies. As an example of the functions it has at that time, the UAV 21 shares information regarding radio wave reception sensitivity with the terminals in the area 13 and/or the base station 1, so as to minimize the possibility of disruption of the propagation path and the error rate. , and select the flight position where the reception strength RSSI is maximum and the S/N ratio is maximum.

In addition, when multiple UAV 21s are flying in the same area at the same time, the multiple UAVs 21 can avoid collision by understanding each other's positions based on GNSS information, etc. Considering information related to communication quality, communication route, delay time, etc., measures the optimization of each other's relative positions, and automatically and dynamically determines the optimization of the own position.

A wireless communication system in which the UAV 21 functions as a communication relay station or base station, as shown in FIG. 3, has the advantage of being able to support ultra-high frequency wireless communication with a short radio wave propagation distance. On the other hand, the problem is how to ensure charging of the UAV 21 while minimizing the negative impact on the communication delay specifications of the wireless protocol used in the wireless network.

Therefore, as shown in FIG. 4, the wireless communication system of this embodiment is placed on the window glass of buildings 2 and 3, and receives and stores power from various electromagnetic waves traveling in the air. We propose array antennas A and B that radiate electric power.

In FIG. 4, it is assumed that the UAV 21 has established communication 38 with an area 13 having terminals operating under local 5G or WAN 5G network conditions.
UAV21 is
・Information from base station 1,
・Positional relationship information and transmission output information with array antenna A or B ・Output information transmitted from UAV 21 to array antenna A or B ・RSSI (field strength) information received from array antenna A or B ・Communication routes 36 and 37 It flies by determining the optimization of its own position in real time based on information such as PER (Packet Error Rate) calculated from communication data from the transmission and reception of test pilot signals used.

At this time, the flight range of the UAV 21 is represented by an area S as a cross-sectional view along the vertical direction. The area S can be defined by the directions (30 to 32, 33 to 35) in which array antennas A and B can perform beam tracking and beam forming. The flight range can be recognized by the UAV 21.

In reality, the flight range of UAV21 can be understood as the volume of an elliptical cone, taking into account the radiation directivity of array antennas A and B, as shown in Figure 5, and the volume V is given by the following formula. It will be done.

[Number 2]
V=2/3・r1・r2・d
V: Volume of flight space r1: Horizontal Fresnel radius r2: Vertical Fresnel radius d: Height when made into an elliptical cone

The UAV 21 determines its own communication quality environment, communication priority, and possible flight range based on the UAV 21's parameters such as RSSI, PER, and communication delay time, and the array antennas A and B that provide control signals to the UAV 21 ( It is possible to recognize autonomously based on information such as pilot signals before signal transmission (to). The UAV 21 can be controlled to satisfy various parameters regarding the flight range and ensure communication quality. There is no limit to the number of UAVs 21 that exist within the flight range (volume V).

However, since the UAV 21 has the role of a relay station or a base station, the quality of communication with the upper base station 1 must be ensured. Therefore, the UAV 21 determines its own charging capacity and calculates the quality of communication with the base station 1. When the charging capacity is equal to or greater than the threshold value, the UAV 21 flies within the flight range (volume V), functions as a relay station, etc., and ensures communication quality in the wireless communication system. On the other hand, if the charging capacity is below the threshold, the UAV 21 can have a UAV 21' identical to the UAV 21 fly within its flight range, transfer its own data to the UAV 21', and have the UAV 21' take over the role. Hereinafter, the same UAV 21' that takes over may be referred to as a "copy machine."

The UAV 21 can fly within the flight range while sharing roles with the UAV 21', which is a copy machine, and can receive wireless power supply from the array antenna A or B. Since the UAV 21 can receive wireless power supply from the array antenna A or B embedded in the window glass of buildings 2, 3, etc., the charging capacity of the UAV 21 is unlikely to fall below the threshold, and the copy operation from the UAV 21 to the UAV 21' is The number of situations where this is necessary can be reduced.

In addition to building window glass, for example, automobile shield glass (window glass),
By arranging a similar array antenna on the glass of a touch panel or the like of a mobile terminal such as a smartphone, the UAV 21 can also receive wireless power from such a window glass. When a failure related to some hardware is detected in the UAV 21, information regarding the cause of the failure is transmitted via the base station 1 etc., and the UAV 21 is ordered to return to the base station (not shown). At that time, the UAV 21 will cause the UAV 21', which is a copy machine, to take over the information and role.

With reference to FIG. 6, an example of antenna units ANT1 to ANT12 forming array antenna A or B, which are arranged on the window glass of a building, will be described. Each of the antenna units ANT1 to ANT12 is configured to be capable of receiving electromagnetic waves from the outside, storing the power in a storage battery, etc., and wirelessly feeding power to the UAV 21 using microwaves. The antenna configured on the window glass may have an array antenna configuration. Therefore, it is also possible to have beam forming and beam tracking functions using a single window glass. The stored power may be used not only for the UAV 21 but also for other purposes.

Window glass in buildings is often arranged in a grid or other regular arrangement. Taking advantage of the structural characteristics of regularly arranged window glass on building walls, window glass with array antennas or single antennas are lined up like ANT1 to ANT12 as shown in FIG. These array antennas configured on each window glass are further lined up as ANTs 1 to 12 as shown in Figure 6, so they can be used as an array antenna as a group of window glasses arranged in an orderly manner on the wall of a building. becomes possible. It is possible to supply the power used by the UAV 21 to the UAV 21 as wireless power supply using microwaves, and also to transmit necessary control signals to the UAV 21 at appropriate timing. Further, wireless power can be supplied to the UAV 21 while appropriately performing beam forming and beam tracking.

Referring to FIG. 7, the circuit diagram and operating principle of array antenna A or B (antenna units ANT1 to ANT12) will be explained. In addition to the antenna units ANT1 to ANT12, the array antenna A or B includes a CPU 40, a down-conversion demodulation mixer 41, RF switches 42 and 45, a preamplifier 43, a power amplifier 44, a power divider 46, and phase shifters 47 to 52. It consists of

The CPU 40 is in charge of controlling the antenna units ANT1 to ANT12, and specifically, generates a baseband signal, demodulates the received signal, estimates the direction of arrival of radio waves based on phase calculation, determines the transmission direction of the radio waves, and controls the received strength/signal. Calculation of PER/delay amount, calculation of attenuator adjustment amount for transmitting and receiving power, etc. are executed.

The RF switches 42 and 45 are connected to the power amplifier 44 side when emitting radio waves and transmitting power to the outside, and are connected to the preamplifier 43 side when receiving power by receiving radio waves from the outside. Operate so that it will be done. The carrier wave generated by the CPU 40 is sent to the power amplifier 44 via the down-conversion demodulation mixer 41 and the RF switch 42, and is amplified. ~12. Note that an attenuator may be placed in the circuit block of FIG. 7 for matching adjustment or output adjustment.

The preamplifier 43 and the power amplifier 44 are not limited to the positions shown in FIG. 7, but may be placed on the antenna units ANT1-12 side from the power divider 46 in one-to-one correspondence with the individual antenna units ANT1-12. Further, an AD converter (ADC) may be installed in the CPU 40, may be provided between the CPU 40 and the mixer 41, or an AD converter may be provided one to one for each antenna unit ANT1 to ANT12. Good too.

Furthermore, the antenna units ANT1 to ANT12 may be arranged to support digital beamforming, analog beamforming, and hybrid beamforming of mixed analog and digital. Generally, a DA converter (Digital-Analog Converter) is placed before the power amplifier 44, and an AD converter (Analog-Digital Converter) is placed before the preamplifier 43.

The circuit block in FIG. 7 is an example of the configuration of a hardware circuit related to beam forming and beam tracking, and the example of the configuration of a circuit that implements beam tracking and beam forming is not limited to FIG. 7. In addition, the basic principles regarding beam forming and beam tracking in both the array antenna configured on a single window glass and the window glass group having the array antenna shown in FIG. 7 will be explained below.
When the arrangement interval of antenna units ANT1 to ANT12 is W (see FIG. 6) and the phase difference between antenna units ANT1 to ANT12 is φ1 to φ12, the phase difference Δφ when power is received by each antenna unit ANT1 to ANT12 is can be given by the following formula.

[Number 3]
Δφ=(2π/λ)・W・sinθ

In the circuit illustrated in FIG. 7, when the time delay amount of the signal received by each antenna unit ANT1 to ANT12 is represented by the signal phase difference φ1 to φ12, the arrival direction of the radio wave is determined based on the phase difference φ1 to φ12. be able to. Furthermore, an acknowledgment signal can be transmitted from the array antenna A or B to notify the destination UAV 21 that the radio wave has been received. When the destination is ANT1 to ANT12, the confirmation response signal is similarly transmitted from UAV21.

Furthermore, the radiation direction of the radio wave to be transmitted at the next timing is determined based on the phase differences φ1 to 12 calculated at the time of reception of the radio wave, taking into consideration the RSSI (electric field strength), PER, etc. received at the time of reception. At this time, the gain amount of the power amplifier 44 or the attenuation amount of the programmable attenuator (attenuator) is also adjusted, and together with the radiation angle θ determined from the phase shift amount, the radio wave shown by the arrow 53 in FIG. Radiation direction is controlled.

How much antenna gain is provided in which direction of radiation when the phase differences φ1 to 12 of each antenna unit ANT1 to ANT12 are set is analyzed in advance when designing the array antenna. According to this preliminary analysis result, the CPU 40 performs beamforming by giving phase differences φ1 to φ12 to each antenna unit ANT1 to ANT12 when transmitting radio waves, and performs beamforming by giving phase differences φ1 to φ12 to each antenna unit ANT1 to ANT12 when receiving radio waves. The phase differences φ1 to 12 of the received signals at 12 are detected to perform beam tracking. In addition, by providing a power detector (not shown), the amount of correction for correcting the mismatch in amplitude or phase that occurs due to the adjustment of the power amplifier 44 when transmitting radio waves and the adjustment of the preamplifier 43 when receiving radio waves can be adjusted. , it is possible to achieve maximum power transfer with phase matching.

The antenna units ANT1 to ANT12 have a function of receiving power from countless radio waves propagating in space and storing the received power in a storage battery. The stored power is wirelessly supplied to the UAV 21 as appropriate through electromagnetic waves transmitted via the antenna units ANT1 to ANT12, thereby charging the UAV 21. Currently, space is crowded with radio waves used by various wireless protocols and flying around. Radio waves cannot be seen visually, and it is difficult to grasp the status of countless radio waves in real time. Such radio waves cause interference phenomena due to crosstalk, causing deterioration in communication quality. By recovering power from such countless radio waves, it can be used as a power source for charging the UAV 21 as described above, and it can also contribute to improving communication quality.

Even in next-generation wireless communication networks, including 5G, in which beamforming is the basic technology, radio waves generated during antenna radiation include radiation other than the main lobe, such as side lobes and back lobes, which depend on the antenna system design. Furthermore, the radio waves radiated by the antenna have characteristics such as non-directionality in the horizontal plane, and include radiated power in directions where the antenna is not needed/used. In the present invention, such unnecessary radio waves can be collected near the transmitting antenna and used as power for charging the UAV 21.

Many of the antennas currently in use radiate a lot of power in a useless direction that is different from the direction in which radio waves should be radiated. According to this embodiment, this wasted power is collected in the vicinity of the transmitting antenna or in the far field region using an array antenna placed on a window glass, etc., and the power is stored and used for another workload. can be converted and reused.

With reference to FIG. 8, a configuration example of an antenna unit arranged on one window glass will be described. The antenna unit may be arranged in a module 64 provided within the window sash 60, and may be configured by arranging antenna elements 62 on the window glass 61. Although the antenna elements 62 are arranged in 4 rows and 4 columns in a grid pattern in the example of FIG. 8, the antenna elements 62 are not limited to this, and it is sufficient that they are arranged with a certain regularity, and the number of antenna elements 62 is However, the present invention is not limited to the illustrated example. The antenna may not be placed over the entire window as shown in FIG. 8, but may be placed over a partial area of the window.

Further, it is not necessary to arrange a plurality of antenna elements 62 in one window, and one antenna element 62 is formed in one window, and the array antenna A or B may be formed. Note that the plurality of antenna elements 62 have an RF module and a power storage circuit shown in FIG. 9 inside the RF line 63 and the conductive window sash 60. Although the antenna element 62 is a rectangular conductive layer in the example shown in FIG. 8, it is not limited to this. The type of antenna element is not limited to pattern antennas, and general sleeve antennas, Yagi antennas, waveguides, horn antennas, leaky coaxial cables, dipole antennas, planar aperture antennas, etc. can also be employed. Further, the antenna may be directional or non-directional.

With reference to FIG. 9, a configuration example of a power storage circuit of an array antenna will be described. This power storage circuit includes a rectifier circuit 65 connected to the antenna unit ANT and a power storage circuit 66. Although the rectifier circuit 65 is a full-wave rectifier circuit in the example of FIG. 9, it is not limited to this. The high frequency power (waveform) received by the antenna unit ANT is rectified through a rectifier circuit 65 including an inductance and a capacitance, and is stored in a power storage circuit 66. For example, the power storage circuit 66 can be mounted as a module 64 in the window sash 60 or the like. The circuit configuration of power storage circuit 66 is not limited to a specific one.

Further, the array antenna A or B is not limited to one that receives power from radio waves of a wireless protocol using radio waves of a specific frequency, and the frequency of the radio waves to receive power does not matter as long as it can be used for power storage. The type of wireless protocol is also not limited to a specific one. Furthermore, there are no restrictions on the wireless power feeding method, software structure, or operation of array antenna A or B.

The pattern antenna to be realized may be a multiband system or a single band system, and whether the pattern antenna is a single band or a multiband system can be selected depending on the design of the antenna. Further, the antenna may have a varicap diode or a structure capable of physically changing the reactance component, and may be configured to dynamically change the frequency characteristics. Furthermore, as an implementation technique for frequency characteristic adjustment, a left-handed circuit using CRLH or metamaterial may be implemented to realize real-time performance.

Referring to FIG. 10, an example of a more detailed structure of array antennas A and B is shown. This array antenna A or B includes a transparent conductor 71 formed in a window 70. The transparent conductors 71 are arranged in an orderly manner in the window 70 and function as an antenna. Each antenna element 71 is composed of, for example, a cross-shaped conductor portion and a conductor perpendicular to the tip of the cross portion, but this is just an example and is not limited to this shape.

Each antenna element 71 includes through conductors (VIA) 73 to 78 at the intersection 72 of the cross-shaped conductor portions. Although the example in FIG. 10 illustrates MIMO array antennas arranged in a grid of 3 rows x 3 columns, the number of antennas in the vertical and horizontal directions of the grid is not limited to a specific number. VIAs 73 to 78, which are feed points provided in each antenna element 71, use the medium 70 as a window as a substrate, and high-frequency signals are received and transmitted at these feed points. FIG. 11 is a diagram simulating a multiband antenna pattern. FIG. 12 shows an example of the frequency characteristics of the antenna circuit of FIG. 11.

The frequency characteristics of the antenna of this embodiment are not limited to having one passband. As shown in FIG. 12, it is possible to have two or more passbands centered on frequencies f1 and f2. Further, the antenna may have a structure using liquid crystal or a metamaterial structure, and may have a function of dynamically adjusting the optimum frequency characteristics.

[effect]
As explained above, according to the system of this embodiment, the following effects can be obtained.
(1) Compared to conventional methods, end-to-end communication distance can be secured over a wider area.
(Explanation) In order to form a wireless communication network using a UAV that can fly in the air as a base station or relay station, the propagation path is formed in three dimensions, unlike the conventional system which is a communication network that is approximately horizontal to the ground. can do. Therefore, it is possible to form a propagation path while avoiding obstacles, and it becomes easier to secure a wider propagation distance than in the past.

(2) It is possible to improve the reliability of the entire communication network using wireless signals.
(Explanation) Since UAV can be used as a relay station or base station, it is possible to avoid obstacles and form a propagation path, so it is possible to suppress the occurrence of multipath and reduce communication quality deterioration due to fading. It can be suppressed. In addition, by using a UAV as a relay station or base station, unlike relay stations or base stations that are conventionally fixed to objects on the ground, the position of the UAV that is a relay station or base station can be determined in real time depending on the communication status. , it becomes possible to spatially optimize. By wirelessly supplying power to UAVs that function as relay stations or base stations from array antennas installed on the windows of buildings, cars, etc., the frequency at which UAVs return to the base station can be reduced. It can be significantly reduced and the continuous flight time will be longer. If the flight time is longer, one UAV can continuously function as a base station and a relay station, improving communication efficiency. Although a considerable amount of delay time occurs when executing the handover function with the substitute machine at the time of changeover, the frequency of changeover can be minimized, so the delay time does not occur in the wireless network of the own machine. It is possible to minimize the frequency of delays.

(3) It becomes physically possible to select the priority order of information to be communicated.
(Explanation) In conventional wireless communication systems, priority selection of wireless signals to be transmitted and received is included in the pilot signal or information-related signal header that is transmitted and received before transmitting and receiving the wireless signal, as is also used in 5G. is being executed according to the status information provided. In an emergency/emergency situation, the UAV's flight path is automatically determined with the highest priority to ensure radio signal quality with any specified information, in addition to conventional electrical priority selection. Physically selected and able to fly.

(4) By collecting radio waves that are unrelated to the main communication that exist in space (energy harvesting) and storing electricity, unnecessary multipath paths on the propagation path can be cut off, and coexistence with other systems can be improved. More effective.
(Explanation) Under conditions such as interference with other systems and inter-cell interference between adjacent cells using the same frequency, recovering the power of unnecessary radio waves is a way to prevent interference waves from being given to other systems, and to prevent interference from other systems. This means that no interference waves are received from the receiver, which leads to suppressing the occurrence of unnecessary multipaths at the receiving point.
However, in communication systems that actively utilize communication routes from multipaths, the collection function can be turned off (OFF) using software.

(5) It becomes possible to perform efficient wireless power supply compared to the conventional technology.
(Explanation) Using a MIMO array antenna, information on the position of a UAV to be supplied with power can be obtained by GNSS or beam tracking using the MIMO array antenna, and wireless power can be supplied to the UAV using beamforming technology. When the MIMO array antenna is embedded in the window of a building, it is possible to reduce obstacles between the MIMO array antenna and the UAV, so power can be supplied while suppressing interference from other systems. Furthermore, since loss between communication paths can be suppressed, highly efficient wireless power supply can be realized.

[Modified example]
Various additions, substitutions, modifications, deletions, etc. can be made to the various configurations shown in the embodiments described above within an obvious range based on known techniques and commonly used means. Furthermore, the communication system is not limited to 5G and 6G, but can be applied to Wi-Fi, LPWA, and all other wireless protocols (modulated signals, non-modulated signals, and types of modulated signals). Further, the present invention has no restrictions on radio communication frequencies and signal frequency bands including AM/FM waves, millimeter waves, optical communications, etc.

Note that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. . Further, it is possible to add, delete, or replace a part of the configuration of each embodiment with other known configurations.

1... Base station, 2, 3... Building, 6... House, 7, 8, 9, 10... Propagation path, 12... Building, 13... Area, 14... Transmission path, 17, 18... Array antenna (repeater)
19-26...Propagation path, 40...CPU, 41...Mixer, 42...RF switch, 43...Preamplifier, 44...Power amplifier, 45...RF switch, 46...Power divider, 47-52...Phase shifter, 61...Window Glass, 62... Antenna element, 63... RF line, 64... Window sash, 65... Rectifier circuit, 66... Power storage circuit, 70... Transparent conductor, 70... Window, 71... Transparent conductor, 72... Intersection, 73-78... Through conductor (VIA), A, B...Array antenna, ANT1-12...Antenna unit.

Claims (8)

a UAV functioning as a relay station or base station;
a terminal that receives a carrier wave via the UAV;
A wireless device comprising: a window glass that includes an antenna that receives power based on electromagnetic waves; and a window glass that wirelessly supplies power received by the antenna and stored power to other electrically operated devices including the UAV via the antenna. Communications system. The wireless communication system according to claim 1, wherein the window glass is architectural window glass, automobile window glass, or glass of a mobile terminal such as a smartphone. The wireless communication system of claim 1 , wherein the window pane includes a device configured to feed stored power to the UAV. 2. The wireless communication system of claim 1, wherein the pane comprises a device configured to locate the UAV by beam tracking and emit electromagnetic waves toward the UAV by beamforming. The wireless communication system according to claim 1, wherein the antenna includes a plurality of antenna units arranged on a plurality of window panes of a building. The UAV autonomously determines its own communication quality environment and communication priority based on various parameters including RSSI, PER, and communication latency information, and satisfies the various parameters related to the flight range, The wireless communication system according to claim 1, having a function of ensuring communication quality. Claim 1, further comprising a second UAV different from the UAV, wherein when the UAV returns to a base station for charging, the second UAV functions as a copy machine that takes over information of the UAV. The wireless communication system described in . The wireless communication system according to claim 1, using a UAV that has a function of significantly reducing the frequency of returning for charging compared to wireless power supply.