COMMUNICATION CONTROL SYSTEM AND COMMUNICATION CONTROL METHOD

A communication control system for controlling communication with a flying object that is taking off or landing, includes a control system including a computation device that executes a prescribed process, and a storage device that is connected to the computation device, and a flying object that communicates with the control system via a base station. The control system stores a radio map indicating a radio quality of each position and each flight altitude of the flying object and each base station. With reference to the radio maps of a plurality of altitudes, a base station that has a favorable radio quality is selected on a taking-off and landing route in a taking-off and landing port.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese patent application No. 2021-199987 filed on Dec. 9, 2021, the content of which is hereby incorporated by reference into this application.

TECHNICAL FIELD

The present invention relates to a communication control system for controlling communication between a flying object and a management system, and more particularly, relates to a communication control method during taking-off and landing.

BACKGROUND ART

In recent years, a system for delivering packages using a flying object, which is called “drone,” that takes off and lands vertically with respect to a landing surface, has been proposed. The delivering system using drones is configured to input data that indicates a horizontal flight plan route for a drone, to acquire a reference altitude value that indicates the altitude of a ground surface below a plurality of points on the flight plan route, and to use, as altitude data on the flight plan route, a value obtained by adding a flight altitude to the altitude reference value of a relevant point. Accordingly, the delivering system allows the drone to fly along the flight plan route without colliding with an obstacle.

In such a delivering system using drones, it is important to cause many drones to arrive at respective destinations and take off/land efficiently. As in the case of planes, drones require a control system. Communication between a flying object such as a drone and a control system is performed wirelessly, movement along a flight plan route is confirmed, and an adjustment such as a route change is made.

The background art of the technical field includes the following documents: Patent Document 1 (WO2016/190793); and Patent Document 2 (WO2018/159794). Patent Document 1 describes a wireless base station including a reception state acquisition unit that acquires either interference levels in multiple cells including an own cell being connected with a user device, or reception communication qualities of the user device in the multiple cells, and a power control unit that restricts transmission power if the interference levels or the reception communication qualities in the multiple cells acquired by the reception state acquisition unit are within a prescribed range.

Patent Document 2 describes a movement adjustment device for adjusting movement of wireless transmitters/receivers that are moving in accordance with a plan based on a route over a wireless communication network, and are simultaneously performing communication for an application having a service requirement in the wireless communication network, the wireless communication network including cells, the movement adjustment device being operable so as to acquire wireless network condition data concerning a cell group including the current cell in which a wireless transmitter/receiver is located and including multiple adjacent cells to which the wireless transmitter/receiver can move, to analyze the wireless network condition data in regards to satisfaction of the service requirement of the application, and to make an adjustment to the planned movement if the analysis indicates that the adjustment will improve satisfaction of the service requirement.

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

The aforementioned Patent Document 1 describes that a flying object moves in accordance with the plan based on a route via a wireless communication network, and flies while analyzing a wireless communication condition in a wireless communication area on a route from the current position to a next destination, and making an adjustment to the movement route so as to satisfy a radio quality required by an application installed in the flying object. However, according to this technology, an optimum cell is selected from among a plurality of cells, and thus, this is not suitable for movement such as taking off or landing along a height direction within one cell. In a case where the communication environment in one cell is deteriorated, or in a case where a plurality of base stations with which connection can be established are found, handover processing for connection switching to an optimum base station occurs. There has been a problem that communication cannot be performed during taking off and landing because a communication interruption occurs during handover processing.

In addition, Patent Document 2 indicates that a radio wave reception level and an interference level are managed by each altitude, and an optimum base station and optimum transmission power at a certain altitude are controlled. However, the total quality of wireless communication to be performed during height-direction movement from a landing start point, where downward movement is started, to a taking-off and landing port, which is a landing area, or to be performed during takeoff from the taking-off and landing port to an altitude at which a horizontal flight is started, is not taken into consideration. Therefore, there has been a problem that handover processing for switching to an optimum base station occurs, and a communication interruption occurs.

Moreover, no consideration is given to radio wave interference from an area above a flying object. Therefore, when a certain flying object is moving downwardly, a radio environment can be changed due to a plurality of flying objects that are on standby above the moving flying object. If the radio environment becomes worse than expected after downward movement for landing is started, the problem arises that handover processing for switching to an optimum base station occurs, and a communication interruption occurs.

In view of the above problems, an object of the present invention is to provide a system for allowing safety takeoff and landing without interrupting wireless communication when landing onto a taking-off and landing port from the air is made and when a takeoff from a taking-off and landing port into the air is made.

Means for Solving the Problem

One representative aspect of the invention disclosed herein is as follows. That is, a communication control system for controlling communication with a flying object that is taking off or landing, including: a control system including a computation device that executes a prescribed process, and a storage device that is connected to the computation device; and a flying object that communicates with the control system via a base station, in which the control system stores a radio map indicating a radio quality of each position and each flight altitude of the flying object and each base station, and with reference to the radio maps of a plurality of altitudes, a base station that has a favorable radio quality is selected on a taking-off and landing route in a taking-off and landing port.

Advantage of the Invention

According to one aspect of the present invention, when a flying object takes off from or lands onto a taking-off and landing port, the flight can be safely made without interruption of wireless communication. Any other problems to be solved, configurations, and effects will become apparent from the following explanation of embodiments.

MODES FOR CARRYING OUT THE INVENTION

According to embodiments of the present invention, in a taking-off and landing system including a flying object101and a control system103, the control system103manages a flight plan, the position, the altitude, and the radio quality condition of the flying object101, creates radio maps on the basis of information on a flight route from the current altitude of the flying object101to the taking-off and landing port102and respective radio qualities at altitudes, selects an optimum base station on the basis of the created radio maps, and indicates the optimum base station to the flying object101. In addition, corresponding to the radio qualities determined from the radio maps, the control system103applies control on re-transmissions of radio data (radio packets) having the same content and control on consecutive transmissions of consecutively transmitting the same packet, to communication between the flying object101and the control system103, so that the reliability of wireless communication is improved. Furthermore, the flying object101has a function of adjusting an antenna directivity for maintaining connection with an optimum base station during taking off and landing on the taking-off and landing port, a body control function for adjusting the antenna directivity, and a function for enabling steady connection with a specific base station.

First Embodiment

Hereinafter, the configuration of a first embodiment according to the present invention will be explained with reference toFIGS.1to7, and processes in this embodiment will be explained with reference toFIGS.8and9. It is to be noted that the present invention is not limited to the following embodiments, and modifications and applications thereof are included within the scope of the present invention under the technical concept of the present invention.

FIG.1is a diagram depicting a schematic configuration of a system according to the first embodiment of the present invention.

The system according to the first embodiment includes the flying object101, the taking-off and landing port102, the control system103, and base stations104and105.

The flying object101is a flying object such as a drone that can fly in a vertical direction. The flying object is, for example, a drone or an eVTOL that can take off and land vertically. It is to be noted that the present invention is applicable not only to an unmanned drone, but also to any other flying object such as a manned flying object that can take off and land vertically, without limited to the shape of the flying object and the flight form including a manned flight, an unmanned flight, an autonomously controlled flight, a flight controlled by a pilot, and the like.

The taking-off and landing port102is formed of a taking-off and landing area106where a flying object takes off and land, and the control system103that controls flight of the flying object101that is taking off or landing. The base stations A104and B105for communicating with the taking-off and landing area106and the flying object101that is taking off or landing, are disposed near the taking-off and landing port102.

The taking-off and landing port102includes one taking-off and landing area106inFIG.1, but may include a plurality of the taking-off and landing areas106.

The control system103is connected with the taking-off and landing port102including the taking-off and landing area106, the base station A104, and the base station B105, and manages the take-off/landing order and the take-off/landing timings of a plurality of the flying objects101. In addition, since the control system103establishes stable communication with the flying object101and the control system103, the control system103makes selection of a base station as a communication destination, and manages the quality of communication between the flying object101and the taking-off and landing area106during movement.

The base station A104is a wireless facility for performing communication between the flying object101and the control system103, and is a base station of a communication carrier providing offering a wireless communication infrastructure for LTE or 5G, or is a communication base station of a private wireless network such as a wireless LAN, a private LTE, local 5G, or the like. It is to be noted that the radio system of the base station A104is not limited as long as the base station A104is a wireless facility or device that can realize wireless communication between the control system103side and the flying object101. The explanation of the base station A104has been given above, but the base station B105has the same configuration.

FIG.2is a block diagram depicting configurations of the flying object101and the control system103according to the first embodiment.

FIG.2depicts a representative configuration of the flying object101. In a case where there are a plurality of the flying objects101, which is not depicted inFIG.2, each of the flying objects101has the same configuration.

The flying object101includes a CPU201, a flight control device202, a positioning device203, a directivity adjustment wireless communication device A204-a1, an antenna204-a2, a directivity adjustment wireless communication device B204-b1, an antenna204-b2, a radio information storage device205, and a communication control device206.

The CPU201is a computation device that controls execution of all functions for controlling the flying object.

The flight control device202controls the body direction and the flight speed in accordance with a flight control program which is executed by the CPU201.

The positioning device203measures current flying position information on the flying object101, and for example, a positioning system such as a GNSS (Global Navigation Satellite System) can be used therefor. The positioning device203may have any other form or system as long as the positioning device203can acquire the position information on the flying object101with high precision. In a case where the positioning device203is a GNSS, the positioning device203can provide accurate time information.

The directivity adjustment wireless communication device A204-a1is a wireless device having a function of adjusting the directivity of the antenna204-a2which is connected with the directivity adjustment wireless communication device A204-a1. The antenna204-a2has a non-directivity characteristic for transmitting/receiving radio waves of a constant intensity in a 360-degrees space, and a directivity characteristic for transmitting/receiving radio waves in a specific direction. For example, these characteristics can be realized by mechanically changing the direction of a directivity antenna, installing an adaptive array antenna having an electrically changeable directivity, or installing two antennas which are a non-directivity characteristic antenna and a directivity antenna. In addition, the directivity adjustment wireless communication device A204-a1is a wireless device having a transmission/reception function corresponding to a wireless communication system such as LTE or 5G utilized as a mobile network, or WiFi utilized as private radio waves.

Like the directivity adjustment wireless communication device A204-a1, the directivity adjustment wireless communication device B204-b1has a transmitting/receiving function corresponding to a wireless system, and a function of adjusting the directivity of the antenna204-b2. The wireless system of the directivity adjustment wireless communication device A204-a1may be identical to, or may be different from that of the directivity adjustment wireless communication device B204-b1. In a case where the wireless systems are identical to each other, services for establishing connection with portable networks provided by different communication carriers, may be offered. Various combinations of the communication system of the directivity adjustment wireless communication device A204-a1and the communication system of the directivity adjustment wireless communication device B204-b1, can be adopted.

The radio information storage device205stores radio information as well as the position information and the time information provided from the positioning device203. The radio information to be stored in the radio information storage device205includes the intensities of radio waves received by the flying object101from the base stations104and105, interference information, a communication speed, and a wireless communication KPI (Key Performance Indicator) such as a packet error rate.

The communication control device206is formed of a communication quality measurement unit207, a re-transmission/consecutive transmission control unit208, a route control unit209, and an antenna directivity adjustment unit210. The communication control device206is a device that controls communication.

The communication quality measurement unit207measures the intensity of a radio wave received by the flying object101from the base station104or105, and the communication success probability of transmission to the base station104or105.

The re-transmission/consecutive transmission control unit208has communication reliability improving functions including a re-transmission function of, in a case where the base station104or105fails to receive radio data (radio packets) transmitted from the flying object101, transmitting the failed data again so as to improve the communication success probability, and a consecutive transmission function of transmitting the same data multiple times such that the base station can receive the data at least one time so as to improve the communication success probability. In addition, the re-transmission/consecutive transmission control unit208has a function of, in a case where the same data sets are received from the base station104or105as a result of a re-transmission function or consecutive transmission function of the base station104or105, keeping one of the data sets and discarding the remaining data sets. To implement the re-transmission function and the consecutive transmission function, the data may have a structure to which a unique sequence number has been given, but any various configurations and implementation means can be adopted because, in the present embodiment, it is sufficient that the same data can be identified.

The route control unit209decides a communication route such that data transmitted from the flying object101is transmitted through either or both of a plurality of the wireless communication devices204-a1and204-b1included in the flying object101. For example, by selection of one communication method having high reliability or by multiplexing, a route the communication reliability of which can be improved is decided. Like the re-transmission/consecutive transmission control unit208, the route control unit209can adopt a variety of communication route decision methods.

The antenna directivity adjustment unit210transmits a control command for adjusting the direction of the antenna204-a2to the directivity adjustment wireless communication device A204-a1, and a control command for adjusting the direction of the antenna204-b2to the directivity adjustment wireless communication device B204-b1. In order to adjust the directions of the antennas, a method using a mechanical structure such as a motor, a method of selecting, from among a plurality of directivity antennas, one corresponding to a proper direction, or a method using an adaptive array antenna is used. Various directivity adjustment methods can be adopted.

The control system103includes a route planning device211, a radio information management device212, a communication device213, a radio information DB214, and the base station A104.

The route planning device211plans a flight route of the flying object101to the taking-off and landing port102.

The radio information management device212includes a radio information registration unit215, a radio information updating unit216, a radio information acquisition unit217, and a radio map creation unit218. The radio information registration unit215provides a user interface (seeFIG.3) for registering the position and altitude of a flying object and radio information into the radio information DB214. The radio information updating unit216updates registered radio information to the latest radio information, or adds the latest radio information to registered radio information. To record and manage one set of radio information for each position and altitude, it is preferable to update the radio information. To record and manage a plurality of data sets in time-series data for each position and altitude, it is preferable to additionally register radio information. The radio information acquisition unit217acquires information recorded in the radio information DB214. The radio map creation unit218calculates one value to be registered in a radio map from radio information being managed by each base station corresponding to the position and altitude or the position, altitude, and time, and from the radio information acquired from the radio information DB214by the radio information acquisition unit217on the flight route created and managed by the route planning device211, the position of a flying object, a base station to be connected, and the position and altitude. For example, a plurality of sets of radio information managed by altitudes in accordance with the flight route are added up, so that the value to be registered in the radio map can be calculated.

The communication device213can perform communication in accordance with the radio system of the flying object101. The communication device213communicates with the flying object101via the base station A104through LTE or 5G which is a portable network, or WiFi which is a private radio system, for example. Here, the communication device213can adopt a variety of communication systems, in the same manner as in the flying object101. In addition, the base station A104is ready to support the communication device213. One base station is connected inFIG.2, but a plurality of base stations may be connected.

The radio information DB214stores radio information acquired by the flying object101, and radio information acquired by the communication device213of the control system103. Since the radio information is managed in each area size, as shown in a radio map management table400(seeFIG.4), an area is calculated from the position and altitude in the radio information measured by the flying object101, and the radio information is stored in a table of the corresponding area. In the present embodiment, a variety of types of databases can be adopted.

FIG.3is a diagram depicting one example of a radio map management screen300according to the first embodiment.

The radio map management screen300includes a managed-information display section301and a radio map registration section306.

The managed-information display section301is a user interface including an indication region302of base stations around the taking-off and landing area, a base station selection region303, an indication region304of a selected radio map, and a position and altitude selection region305.

In the indication region302of a base station around the taking-off and landing area, a base station that is present around the taking-off and landing port selected in the base station selection region303is indicated. For example, in the depicted indication region302of a base station around the taking-off and landing area, the taking-off and landing port102and base stations307to309are plotted on a map.

The indication region304of a selected radio map indicates a radio map of the base station selected in the base station selection region303, at the position and altitude selected in the position and altitude selection region305. A base station is selected in the base station selection region303, a selection button314in the position and altitude selection region305is operated, and then, a display button311is operated to display the radio map. However, the display button311is not necessarily required. A corresponding radio map may be automatically displayed after a base station, a position, and an altitude are selected. A variety of implementation forms can be adopted.

The radio map registration section306is a user interface that is used to register a new radio map, register an additional radio map, or update a radio map. A position314, an altitude315, an area size316of a radio map to be registered, and a radio map file317for expressing radio information are designated for the flying object101, and a registration button318is operated to register a radio map. As the format of the radio map file, any format can be adopted as long as the format is a predetermined one such as a CSV (Comma Separated Values) format or a JSON (JavaScript Object Notation) format.

FIG.4is a diagram depicting a configuration example of the radio map management table400that is managed inFIG.3.

In the radio map management table400, a flying object position401, an area size402, a base station ID403, and a radio map ID404, are managed by columns. The position (X, Y) of the flying object position401is expressed by latitude and longitude information, and the altitude (Z) is expressed by the altitude with respect to the ground surface, for example. In addition, the area size402designates the mesh size of the radio map. The radio maps are managed by altitudes (Z) of the flying object position401such that each of the radio maps is centered on the position (X, Y). Therefore, radio information acquired at a certain position (X, Y) is a value representing a distance to a position away from the position (X, Y) by a value obtained by dividing the area size402by2.

The area size402which is recorded in the radio map management table400may be changed depending on the altitude, or may be set to be constant irrespective of the altitude. If the area size is managed so as to be changed depending on the altitude, the difference in communication distance characteristics among the altitudes can be addressed. For example, communication at a high altitude can be regarded as line-of-sight communication because there are no or less obstacles at such a high altitude than at a low altitude. That is, radio wave attenuation due to the communication distance at a high altitude is less than at the ground. Therefore, radio information may be managed by a large area. An effect of reducing the storage area in a database, and being capable of making a determination corresponding to communication distance characteristics, can be obtained. On the other hand, when management based on equal area sizes is performed regardless of altitudes, as depicted inFIG.7, the management of radio maps becomes easy.

The radio map ID404is identification information or a name for uniquely identifying a registered radio map.

FIG.5is a diagram depicting one example of a table configuration of a radio map.FIG.5indicates an example of a radio map405.

In the radio map405, cells501arranged in a vertical direction (having the same X-axis value) constitute each column, and cells502arranged in a horizontal direction (having the same Y-axis value) constitute each row. The radio map405is formed of values503of cells that are sectioned by the columns and the rows. In the present embodiment, the values503are expressed by strong, medium, and weak levels. Alternatively, numerical values directly representing measurement results as radio information, or numerical values representing radio qualities such as radio intensities, packet error rates, or delays, are sufficient. A variety of values can be adopted therefor.

FIG.6is a diagram depicting one example of a route for landing from a certain altitude to the taking-off and landing port, and radio maps, and depicts selection of values on radio maps corresponding to a flight route for landing from a position602of the flying object101onto a taking-off and landing point601in the taking-off and landing port102.

InFIG.6, a radio map405of an altitude of 20 m, a radio map406of an altitude of 50 m, and a radio map407of an altitude of 100 m, are managed as radio maps around the taking-off and landing port102. The area sizes in the respective radio maps are 10, 20, and 40 m, as shown in the radio map management table400inFIG.4. Here, corresponding to a passing route, radio information which represents a radio quality at a landing time is calculated from three values: the value of one cell of a mesh which is sectioned into 16 parts in the radio map405; the value of one cell of a mesh which is sectioned into 4 parts in the radio map406; and the value of a cell of a mesh which is not sectioned in the radio map407. In this manner, the management can be performed while changing an area size corresponding to an altitude.

FIG.7is a diagram depicting one example of a route for landing from a certain altitude onto the taking-off and landing port, and radio maps, and depicts selection of values of radio maps corresponding to a flight route for landing from a position702of the flying object101onto a taking-off and landing point701in the taking-off and landing port102.

In the example depicted inFIG.7, the radio map405of an altitude of 20 m, a radio map703of an altitude of 50 m, and a radio map704of an altitude of 100 m, are managed as radio maps around the taking-off and landing port102. The area sizes in all the radio maps are 10 m. In the same manner as inFIG.6, corresponding to a passing route, radio information which represents a radio quality at a landing time is calculated from three values: the value of one cell of a mesh which is sectioned into 16 parts in the radio map405; the value of one cell of a mesh which is sectioned into 16 parts in the radio map703; and the value of one cell of a mesh which is sectioned into 16 parts in the radio map704. In this manner, the management can be performed with the area size set to be equal to each other regardless of an altitude.

Next, with reference toFIGS.8to10and on the basis of radio maps, an explanation will be given of the flow of controlling wireless communication during taking off and landing of the flying object101, and of an operation flow of determining control information.

FIG.8is a sequence diagram depicting a control flow in accordance with which the control system103creates a radio map for a certain flying object, and communication is performed between the flying object101and the control system103.

The radio information registration unit215receives a new radio map registration request from the radio map registration section306of the radio map management screen300(800), and makes an inquiry about the presence/absence of an existing radio map to the radio information acquisition unit217(801). Upon receiving the existing data confirmation request, the radio information acquisition unit217tries to acquire a requested radio map from the radio information DB214. When the requested radio map is successfully acquired, an existing radio map is present. When acquisition of the requested radio map fails, no existing map is present. The radio information acquisition unit217sends a determination result803in response to the existing data confirmation request, through the radio information acquisition unit217to the radio information registration unit215. In accordance with the returned determination result803, the radio information registration unit215executes a radio map registration, updating, and adding process (804).

Next, when the communication quality measurement unit207of the flying object101receives a communication start request805, a process for checking the quality of communication between the base station104connected to the control system103and the flying object101, is executed. First, the communication quality measurement unit207of the flying object101transmits the position, the altitude of the flying object101, and acquired radio information to the communication device213of the control system103(806). The communication device213transmits the received position, altitude, and radio information to the radio information acquisition unit217(807), and acquires a relevant radio wave map on the basis of the position and the altitude (810). In addition, new radio information received from the flying object101is transmitted to the radio information updating unit216(808), and radio information updating is performed (809).

The radio map creation unit218creates a radio map between the flying object101and the taking-off and landing port on the basis of the radio information acquired from the radio information acquisition unit217(811). The details of this radio map creation process811will be explained later with reference toFIG.10. The radio map creation unit218transmits the created radio map to the communication device213(812). The communication device213transmits the received radio map to the flying object101through wireless communication (813). Here, the communication device213determines a radio wave reliability on the basis of the created radio map (815). In the reliability determination process815, in order to improve the communication reliability, operation parameters for the re-transmission/consecutive transmission control unit and the route control unit of the communication device213are determined, and communication with the flying object101is performed by a determined communication method. The re-transmission/consecutive transmission control unit of the communication device213in the control system also makes determinations in the same manner as in the re-transmission/consecutive transmission control unit208and the route control unit209, so that the communication reliability is improved.

Upon receiving the radio map, the communication quality measurement unit207determines the necessity of radio control (814) in the same manner as in the communication device213of the control system103, so that the number of times of performing consecutive transmissions/re-transmissions and a transmission route are determined. The details of the radio control determination process814will be explained later with reference to FIG.9.

FIG.9is a flowchart of the radio control determination process814of determining necessity of radio control with respect to the flying object. It is to be noted that the flowchart inFIG.9indicates control that is performed in a case where all the functions of the first embodiment and second and third embodiments, which will be explained later, are installed. Steps corresponding to functions that are not installed in an embodiment, are skipped. That is, the first embodiment corresponds to steps S704to S705, the second embodiment corresponds to steps S706to S707, and the third embodiment corresponds to step S703.

In the radio control determination process814, in step S901first, the communication quality measurement unit207receives radio maps from the radio map creation unit218. In step S902, a base station candidate of a connection destination is designated from a plurality of the received radio maps. Since radio maps are managed for each base station, there is a possibility that one or more connection candidates are present. In step S902, for each of the connection candidates, a base station candidate for ensuring a communication reliability that is suitable as a connection destination for which steps S903to S910will be executed, is designated. Then, the process proceeds to step S903.

In step S903, whether or not an applicable base station can be designated is determined. In a case where a specific base station can be designated, the process proceeds to step S908because continuous connection can be established with the designated base station without controlling the object body or adjusting the antenna directivity. In contrast, in a case where a specific base station cannot be designated, the process proceeds to step S904.

In step S904, whether or not the directivity of an antenna of the flying object101is adjustable, is determined. In a case where a structure capable of adjusting the antenna directivity is provided to obtain a desired directivity, the process proceeds to step S905. In a case where the antenna directivity is not adjustable, the process proceeds to step S906.

In step S905, the antenna directivity is adjusted toward a direction for improving a directivity toward the base station so as to continue communication with the base station. After an adjustment parameter is determined, the process proceeds to step S908.

In step S906, whether or not the antenna directivity can be adjusted by body control of the flying object, is determined. In a case where the directivity can be adjusted with respect to the base station when the flying object body is rotated in a horizontal direction, the process proceeds to step907(S907). In a case where the directivity is not adjustable, the process proceeds to step S908.

In step S908, the number of times of performing re-transmissions and the number of times of performing consecutive transmissions for improving the reliability of communication with the base station, are determined. In a case where the same radio packet is re-transmitted by the number of times determined in this step, and where the same application data is consecutively transmitted by the number of times determined in this step (for example, the number of times of performing re-transmissions and the number of times of performing consecutive transmissions are set to 2 and 3, respectively), up to 9 opportunities (the number of times of performing consecutive transmissions×the number of performing re-transmissions+1) of performing wireless transmissions can be obtained for the same application data, compared to a case where the number of times of performing re-transmissions is set to zero and the number of times of performing consecutive transmissions is set to zero. Therefore, to attain successful wireless communication, it is sufficient that at least one of the up to 9 radio packets reaches the destination base station. Accordingly, the reliability is improved. In the aforementioned manner, parameters for improving the reliability of wireless communication are determined in this step. Besides the number of times of performing re-transmissions or the number of times of performing consecutive transmissions, a function for improving the communication reliability can be added to the present step in the present embodiment. A variety of reliability improving functions can be adopted.

In step S909, whether or not there is an unchecked base station is confirmed. In a case where there is an unchecked base station, the process returns to step S902to execute the process for the next base station candidate. In contrast, in a case where the process for all the base station candidates has been executed, the process proceeds to step S910.

In step S910, an optimum base station is selected from among the base station candidates in view of the radio maps and the communication reliability. For example, in a case where the intensity of radio waves from a base station is taken as a reference, a base station having the highest radio wave intensity on a route from the current position of the flying object, which is calculated from a plurality of radio maps being managed by altitudes, to a landing point, is selected. After a base station is selected, the process proceeds to step S911.

In step S911, whether there is a yet-to-be-set communication device is determined. The flying object101has one or more wireless communication devices. Thus, in a case where any one of the communication devices has not been set, the process proceeds to step S902. In a case where all the communication devices have been set, the process proceeds to step S912to execute the process for the next communication device. On the other hand, in a case where the processes for all the communication devices have been executed, the process ends.

FIG.10is a flowchart of the radio map creation process811.

In the radio map creation process811, in step S1101first, whether or not there is an existing radio map corresponding to the position and altitude, is determined. In a case where there is an existing radio map, the process proceeds to step S1002. In a case where there is no existing radio map, a radio map corresponding to the next position and altitude is searched for.

In step S1102, an applicable radio map is acquired from the radio information DB204, and then, the process proceeds to step S1003.

In step S1003, whether or not radio maps of all altitudes within a section from the landing start point of the flying object101to the taking-off and landing port102or a section from the taking-off and landing port102to a flight altitude after taking off, have been acquired, is determined. In a case where the radio maps of all altitudes have been acquired, the process proceeds to step S1004. In a case where any one of the radio maps has not been acquired, the process returns to step S1001.

In step S1004, in order to acquire radio information on a position on the flight route of the flying object101, a relevant cell in each of the radio maps is extracted on the basis of the position information and the cell size, and a radio information value of the extracted cell is stored. After the cell values are extracted and stored from all the radio maps, the process proceeds to step S1005.

In step S1005, a map combining process using all the values of the relevant cells in the radio maps stored in step1004is performed. For example, in the map combining process, all the cell values may be added up. In the map combining process, a variety of modifications of, for example, performing the addition while changing the weight corresponding to each altitude, may be made. After the map combining process is completed, the process ends in step S1006.

As explained so far, according to the first embodiment, disconnection of wireless communication due to handover processing during taking off and landing of the flying object101can be suppressed, and further, the reliability of wireless communication can be improved to be suited for the route.

Second Embodiment

In the first embodiment, in order to suppress handover during taking off and landing, a mechanical structure capable of adjusting an antenna directivity for maintaining connection with a certain base station is required in the antenna204-a2or the antenna204-b2, so that the body weight of the flying object is increased. The second embodiment offers an example of addressing this problem by changing the body direction of a flying object itself without requiring a mechanical structure having an adjustment function. The configuration of the flying object of the second embodiment depicted inFIG.11is different from that of the first embodiment. This configuration corresponds to steps S706to S707of the flowchart inFIG.9. It is to be noted that a configuration different from that in the first embodiment will be mainly explained in the second embodiment, and a configuration or a process identical to that in the first embodiment is denoted by the same reference numeral, and an explanation thereof will be omitted.

FIG.11is a block diagram depicting a configuration of a flying object1101according to the second embodiment.

The flying object1101includes the CPU201, the flight control device202, the positioning device203, a wireless communication device A1104-a1, the antenna204-a2, a wireless communication device B1104-b1, the antenna204-b2, the radio information storage device205, and a communication control device1106.

The CPU201, the flight control device202, the positioning device203, the antenna204-a2, the antenna204-b2, and the radio information storage device205are identical to those of the first embodiment.

The wireless communication device A1104-a1and the wireless communication device B1104-b1are wireless devices each having a transmission/reception function corresponding to a wireless communication system such as LTE or 5G utilized as a mobile network, or WiFi utilized as private radio waves. The wireless system of the wireless communication device A1104-a1may be identical to or may be different from that of the wireless communication device B1104-b1.

The communication control device1106is formed of the communication quality measurement unit207, the re-transmission/consecutive transmission control unit208, the route control unit209, and a directivity adjustment unit1110, as in the first embodiment. The communication control device1106controls communication.

The directivity adjustment unit1110indicates, to the flight control device202of the flying object101, a body direction with respect to a base station to be connected in which the quality of communication with the base station can be favorably maintained. That is, in the second embodiment, the direction of the antenna that is fixedly mounted on the object body is controlled by controlling the direction of the flying object101.

As explained so far, according to the second embodiment, disconnection of wireless communication due to handover processing during taking off and landing of the flying object101can be suppressed without installation of an antenna directivity adjustment mechanism which may become a cause of a weight increase of the flying object101, and further, the reliability of wireless communication can be improved to be suited for the route.

Third Embodiment

In the second embodiment, in order to suppress handover during taking off and landing, it is necessary to control the body direction of the flying object101so as to maintain connection with a certain base station. Therefore, motion of the object body is restricted. The third embodiment offers an example of addressing this problem without using a mechanical control function. The configuration of a flying object of the third embodiment depicted inFIG.12is different from those of the first and second embodiments. This configuration corresponds to step S703of the flowchart inFIG.9. It is to be noted that, a configuration different from that in the first or second embodiment will be mainly explained in the third embodiment, and a configuration or a process identical to that in the first or second embodiment is denoted by the same reference numeral, and an explanation thereof will be omitted.

FIG.12is a block diagram depicting a configuration of a flying object1201according to the third embodiment.

The flying object1201includes the CPU201, the flight control device202, the positioning device203, a wireless communication device1204-a1, an antenna1204-a2, the radio information storage device205, and a communication control device1206.

The CPU201, the flight control device202, the positioning device203, and the radio information storage device205are identical to those in the first embodiment and the second embodiment.

The wireless communication device1204-a1is a wireless device having a transmission/reception function corresponding to a wireless communication system such as LTE or 5G utilized as a mobile network, or WiFi utilized as private radio waves. The wireless communication device1204-a1has a function of establishing connection with a designated base station. For example, an SSID for identifying an access point of a wireless LAN, or a base station ID of a mobile network can be used to designate a connection destination. If such an SSID or a base station ID can be designated, unintended switching to another base station can be suppressed. Neither the antenna directivity adjustment mechanism of the first embodiment nor the body control process of the second embodiment is required.

The communication control device1206is formed of the communication quality measurement unit207, the re-transmission/consecutive transmission control unit208, and the route control unit209, which are the same as in the first embodiment. The antenna directivity adjustment unit210of the first embodiment and the directivity adjustment unit1110of the second embodiment are not required.

As explained so far, according to the third embodiment, disconnection of wireless communication due to handover processing during taking off and landing of the flying object101can be suppressed without any restriction on flight of the flying object101, and further, the reliability of wireless communication can be improved to be suited for the route.

According to the aforementioned embodiments, radio information in which a flight altitude and a flight route are taken into consideration can be obtained, and disconnection of communication with a wireless station due to unnecessary handover can be suppressed by radio information management and communication control during taking off and landing of the flying object101.

It is to be noted that the present invention is not limited to the aforementioned embodiments, and encompasses various modifications and equivalent configurations within the concept of the attached claims. For example, the aforementioned embodiments have provided a detailed explanation of the present invention for easy understanding. The present invention is not necessarily limited to an embodiment including all the explained configurations. In addition, a part of the configurations of any one of the embodiments may be replaced with a configuration of another one of the embodiments. Moreover, a configuration of any one of the embodiments may be added to a configuration of another one of the embodiments. Furthermore, addition, deletion, or replacement of another configuration may be made for a part of the configurations of each of the embodiments.

In addition, the aforementioned configurations, functions, processing units, and processing means may be implemented by hardware by designing a part or all of them on an integrated circuit, for example, or may be implemented by software by a processor interpreting and executing a program for executing the functions.

Information on the program for executing the functions, a table, a file, etc., can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a recording medium such as an IC card, an SD card, or a DVD.

In addition, a control line or an information line that has been described is considered to be necessary in the explanation, and thus, not all control lines or information lines that need to be mounted have been described. It can be considered that almost all the structures are mutually connected in actuality.