JP7767368B2 - How to create a database - Google Patents

Description

The present invention relates to a server system, a vehicle, a database creation method, and a database creation device.

Technology for notifying a moving vehicle or a mobile terminal used within the vehicle of a base station suitable for switching (handover) to is known. For example, Patent Document 1 describes a pedestrian detection device that includes a ground-side imaging means for capturing images of the road, a ground-side pedestrian recognition means for detecting the position and direction of movement of pedestrians on the road from the captured images, a ground-side communication means for transmitting data on the installation position of the ground-side imaging means and data on the pedestrian's position to the vehicle, an on-board sensor mounted on the vehicle for detecting the presence or absence of an object in front of the vehicle and the distance to the object, a vehicle-side communication means for receiving data from the ground-side transmission means, and a vehicle-side pedestrian recognition means for determining the positional relationship between the ground-side imaging means and the on-board sensor based on the received data, and recognizing an object corresponding to a pedestrian detected on the ground side as a pedestrian on the vehicle side based on the position and direction of movement of the detected pedestrian and the positional relationship between the ground-side imaging means and the on-board sensor.

Japanese Patent Application Laid-Open No. 2008-294745

However, the above-mentioned conventional technologies leave the task of identifying the optimal base station to each individual vehicle. This places a heavy burden on each vehicle's computer resources. Furthermore, the information that vehicles obtain through communications often contains important information that can affect the vehicle's behavior and the safety of other vehicles and pedestrians. For this reason, communication between base stations and vehicles must be stable. However, to achieve this stability, the process of identifying base stations must be fast and highly accurate. Such high-performance base station identification places an even greater burden on each vehicle's computer resources. Another problem is that equipping all vehicles with such advanced functionality is not practical from a cost perspective.

A server system according to one aspect of the present invention comprises at least a server-side storage unit having a database that stores, for multiple points in time, sets of information including the vehicle's position at a given point in time, information about the base station that emitted radio waves received by the vehicle when the vehicle was at that position, and the strength of the radio waves received by the vehicle when the vehicle was at that position; a receiver that receives various information including the position of a target vehicle; an identifier that identifies the optimal base station for the target vehicle when the receiver receives the various information based on the various information received by the receiver and the database; and a transmitter that transmits to the target vehicle an instruction to connect to the base station identified by the identifier.

A vehicle according to another aspect of the present invention includes a detection unit that detects the vehicle's position, a second transmission unit that transmits various information including the vehicle's position detected by the detection unit to a server system that identifies a base station based on the various information, a second reception unit that receives from the server system a connection instruction to the base station identified by the server system, and a connection unit that connects to the base station in response to the connection instruction received by the second reception unit.

A database creation method according to another aspect of the present invention includes the steps of: acquiring, in a database creation device, sets of information for multiple points in time, the sets of information including at least the vehicle's position at a single point in time, information about the base station that emitted radio waves received by the vehicle when it was at that position, and the strength of the radio waves received by the vehicle when it was at that position; and creating a database by using the database creation device to accumulate the multiple sets of information acquired in the step of acquiring the sets of information.

A database creation device according to another aspect of the present invention includes an acquisition unit that acquires, for multiple points in time, sets of information including at least the vehicle's position at a given point in time, information about the base station that emitted radio waves received by the vehicle when it was at that position, and the strength of the radio waves received by the vehicle when it was at that position, and a creation unit that creates a database by accumulating the multiple sets of information acquired by the acquisition unit.

Each aspect of the present invention may be realized by a computer. In this case, the scope of the present invention also includes a program that causes a computer to operate as each unit (software element) of the server system and database creation device, thereby realizing the server system and database creation device on the computer, and a computer-readable recording medium on which the program is recorded.

1 is a block diagram showing a functional configuration of a communication system according to an embodiment of the present invention. 10 is a diagram illustrating a part of a process executed by a database creation device included in the communication system according to the embodiment when creating a database. FIG. 10 is a diagram showing an example of a base station switching position when a vehicle constituting the communication system according to the embodiment travels on a lane. FIG. FIG. 2 is a block diagram showing an example of a functional configuration of a server system that constitutes the communication system according to the embodiment. 10 is a diagram showing an example of a situation in which a server system included in the communication system according to the embodiment does not transmit a connection instruction to a base station to a target vehicle. FIG. 10 is a diagram showing an example of a situation in which a server system included in the communication system according to the embodiment transmits information about a detour to a target vehicle. FIG. 10 is a diagram showing an example of a situation in which a server system included in the communication system according to the embodiment transmits a network policy to a target vehicle. FIG. FIG. 10 is a block diagram showing another example of the functional configuration of the server system that constitutes the communication system according to the embodiment. FIG. 2 is a block diagram showing a functional configuration of a vehicle that constitutes the communication system according to the embodiment. 1 is a flowchart illustrating a flow of a database creation method according to an embodiment of one aspect of the present invention.

First, we will explain in detail an embodiment of the present invention.

<Communication Systems>
First, an embodiment of one aspect of the present invention (communication system 100) will be described. FIG.

The communication system 100 enables vehicles 3 equipped with wireless communication capabilities to appropriately switch base stations (handover). As shown in Figure 1, the communication system 100 comprises a database creation device 1, a server system 2, and multiple vehicles 3. These are connected to each other via a communication network N.

[Database creation device]
Next, a specific configuration of the database creation device 1 constituting the communication system 100 will be described. Fig. 2 is a diagram illustrating part of the processing executed by the database creation device 1 when creating a database. Fig. 3 is a diagram showing an example of the switching position of the base station C when a vehicle 3 constituting the communication system 100 is traveling on a lane L.

The database creation device 1 comprises a device-side control unit 11, a device-side receiving unit 12, and a device-side storage unit 13.

[Device-side receiver]
The device-side receiving unit 12 receives various data, various signals, etc. from the vehicle 3 or other devices X (see FIG. 4 ), which will be described later, via wired or wireless communication. The device-side receiving unit 12 according to this embodiment is configured by a communication module.

[Device-side storage section]
The device-side storage unit 13 is capable of storing a database D. The database is a collection of information sets including at least location information, base station information, and intensity information for multiple points in time. The location information is information indicating the location of the vehicle 3 at a certain point in time. The base station information is information regarding the base station that emitted the radio waves received by the vehicle 3 when it was at that location. The intensity information is information indicating the intensity of the radio waves received by the vehicle 3 when it was at that location. The device-side storage unit 13 may be in a state where it stores an updatable database D. The device-side storage unit 13 may also be detachable and usable as a server-side storage unit 22 of the server system 2 described below.

[Device-side control section]
The device-side control unit 11 includes a device-side acquisition unit 111 and a creation unit 112 .

(device side acquisition unit)
The device-side acquisition unit 111 acquires sets of information for multiple points in time, including at least location information at one point in time, base station information from which the vehicle 3 emitted radio waves received by the vehicle 3 when it was at that location, and intensity information received by the vehicle 3 when it was at that location. The device-side acquisition unit 111 according to this embodiment acquires the sets of information from the vehicle 3 by controlling the device-side receiving unit 12 so that the device-side receiving unit 12 receives the sets of information.

The device-side acquisition unit 111 in this embodiment acquires latitude (Lat) and longitude (Lon) as location information every time a predetermined time elapses. Furthermore, in addition to latitude and longitude, the device-side acquisition unit 111 in this embodiment also acquires altitude (Alt) and latitude/longitude accuracy (Horizon confidence) as location information every time a predetermined time elapses. For example, "accuracy of 1 m" means that the point indicated by the true latitude and longitude exists within a circle with a radius of 1 m centered on the point indicated by the acquired latitude (Lat) and longitude (Lon) with a probability of approximately 95% (2σ). Furthermore, in this embodiment, the device-side acquisition unit 111 acquires, in addition to location information, a vehicle ID, lane ID, node ID, distance from the node along the lane, and road speed limit every time a predetermined time elapses. For example, "the distance is 1 m" means that when a map match (usually a process of finding the foot of a perpendicular line from a point indicated by the latitude and longitude to a line segment representing the lane) is performed on a certain latitude and longitude, the point on the lane is located 1 m away from the node. The device-side acquisition unit 111 stores the acquired position information for each time in a format (table) such as that shown in Table 1 below. The device-side control unit 11 may calculate the speed of the vehicle 3 based on position information acquired by the device-side acquisition unit 111 at least two points in time. In this case, the device-side acquisition unit 111 may change the predetermined time until the next position information is acquired depending on the calculated speed. The index representing the accuracy of the latitude and longitude may be, for example, Distance RMS (DRMS).

The device-side acquisition unit 111 according to this embodiment acquires the frequency (band), PCI, NRCGI, TA, RSRP, RSRQ, and SINR of the base station (serving cell) as base station information every time a predetermined time elapses. The device-side acquisition unit 111 according to this embodiment also acquires the vehicle ID every time a predetermined time elapses. When a base station switch occurs, the device-side acquisition unit 111 also acquires the event name, frequency (band), PCI, RSRP, RSRQ, and SINR as information about the target base station (target cell). The device-side acquisition unit 111 also stores the acquired base station information for each time in a format (table) such as that shown in Table 2 below.

(Creation Department)
The creation unit 112 creates a database D in the device-side storage unit 13 by accumulating the sets of information acquired by the device-side acquisition unit 111. If the database D is already stored in the device-side storage unit 13, the creation unit 112 updates the database D.

The location information acquired by the device-side acquisition unit 111 is determined by the GPS equipped in the vehicle 3. On the other hand, base station information is received from a base station. That is, the location information and base station information are generated by different devices. Therefore, the time when a certain piece of location information is acquired does not match the time when base station information is acquired at the same timing. For example, according to Table 2 above, base station information is acquired at 7:00:00.400, but according to Table 1 above, no location information was acquired at this time. Therefore, as shown in Figure 2, the creation unit 112 in this embodiment calculates the location information at a third time (here, 7:00:00.400), which is a time between the first time and the second time and is the time when the base station information was acquired, by linear interpolation based on the location information at the first time (here, 7:00:00.000) and the location information at the second time (here, 7:00:00.500), which is the acquisition time after the first time. The creation unit 112 then stores a pair of the location information at the third time and the base station information at the third time in the database. Note that if the relationship between the first time or the second time and the acquisition time of the base station information satisfies a predetermined condition (for example, the difference between the two is within one second), the creation unit 112 may be configured to associate the first time or the second time, whichever is closer to the acquisition time of the base station information, with the acquired information, without performing linear interpolation.

The creation unit 112 also classifies the time-specific location information and time-specific base station information by vehicle type based on the vehicle ID. The creation unit 112 then further classifies the classified data by lane based on the lane ID. The device-side acquisition unit 111 also stores the classified information for each vehicle type and lane in a form (table) such as that shown in Table 3 below. As shown in Figure 3, each row in this table indicates that when a vehicle 3 of vehicle type X is traveling on lane L with lane ID 100, it switches from the base station (PCIX) with which it had been communicating to a new base station (PCIY) at a location P that is a corresponding distance away from each node N on lane L.

[Database creation equipment and others]
The database creation device 1 may include a device-side transmitting unit that transmits various data, various signals, etc. to the server system 2 or another device X via a wired or wireless connection. The device-side transmitting unit may be an device-side communication unit integrated with the device-side receiving unit 12. The device-side control unit 11 may include a transmission control unit that controls the device-side transmitting unit so that the device-side transmitting unit transmits at least a portion of the data in the database D created by the creation unit 112 to the server system 2 or another device X.

[Server system]
Next, a specific configuration of the server system 2 constituting the communication system according to the embodiment will be described. Fig. 4 is a block diagram showing an example of the functional configuration of the server system 2. Fig. 5 is a diagram showing an example of a situation in which the server system 2 does not transmit an instruction to connect to a base station to the target vehicle 3. Fig. 6 is a diagram showing an example of a situation in which the server system 2 transmits information about a detour to the target vehicle 3. Fig. 7 is a diagram showing an example of a situation in which the server system 2 transmits a network policy to the target vehicle 3. Fig. 8 is a block diagram showing another example of the functional configuration of the server system 2.

The server system 2 identifies base stations based on various information. As shown in FIG. 4, the server system 2 includes a server-side control unit 21, a server-side storage unit 22 (storage unit), a server-side receiving unit 23 (receiving unit), and a server-side transmitting unit 24 (transmitting unit).

[Server-side storage unit]
The server-side storage unit 22 has a database D. The database D is the same as that of the database creation device 1. That is, the database D stores a set of information including at least location information, base station information, and intensity information at a single point in time for multiple points in time.

[Server-side receiving section]
The server-side receiving unit 23 wirelessly receives various data, various signals, and the like from the vehicle 3 or other devices X. The server-side receiving unit 23 according to this embodiment is configured by a communication module.

[Server-side transmission unit]
The server-side transmitter 24 wirelessly transmits various data, various signals, etc. to the vehicle 3 or other devices X. The server-side transmitter 24 according to this embodiment is configured as a communication module. Note that the server-side transmitter 24 may be integrated with the server-side receiver 23 as a server-side communication unit.

[Server-side control unit]
The server-side control unit 21 includes a reception control unit 211 , a determination unit 212 , a second determination unit 213 , an identification unit 214 , a generation unit 215 , and a transmission control unit 216 .

(Reception control section)
The reception control unit 211 controls the server-side receiving unit 23 so that the server-side receiving unit 23 receives various types of information. The various types of information received by the server-side receiving unit 23 include location information. Furthermore, the various types of information received by the server-side receiving unit 23 according to this embodiment further includes the traveling direction (lane information) of the target vehicle 3. Furthermore, the various types of information received by the server-side receiving unit 23 according to this embodiment further includes the vehicle model of the target vehicle 3. The reception control unit 211 according to this embodiment controls the server-side receiving unit 23 to receive location information from the vehicle 3. Meanwhile, the reception control unit 211 controls the server-side receiving unit 23 to receive the traveling direction of the target vehicle 3 from another device X. The other device X has map information. The other device X acquires location information from the target vehicle 3 and identifies the traveling direction of the target vehicle 3 based on the map information and location information. The other device X may be a server different from the server system 2, or may be part of the server system 2. The reception control unit 211 may also receive location information from the other device X.

The reception control unit 211 also controls the server-side receiving unit 23 so that the server-side receiving unit 23 receives the second various information. The second various information received by the server-side receiving unit 23 includes at least one of the shape of the road on which the target vehicle 3 is traveling (highway, general road, etc.), the area in which the target vehicle 3 is traveling, and the driving plan of the target vehicle 3.

(Judgment Department)
The determination unit 212 determines whether a predetermined switching-unnecessary condition is satisfied. The switching-unnecessary condition includes, for example, whether the time spent in the coverage area (hereinafter, the radio wave coverage area) of the target base station is less than a predetermined time, whether the strength or quality of the radio waves emitted by the target base station is less than a predetermined value, or whether the target base station is a congested cell. The determination of whether the time spent in the coverage area is less than the predetermined time is made, for example, based on whether, after switching to a new base station, the vehicle will immediately return to the original base station or will immediately switch to another base station. Specifically, as shown in FIG. 5 , a vehicle 3 traveling on a road R passing through the coverage area AA of a base station (PCIA) enters the coverage area AB of a target base station (PCIB), but the lane L curves toward the original base station (PCIA), causing the vehicle 3 to return to the coverage area AA of the base station (PCIA) in a short time. In this case, the vehicle 3 determines that the time spent in the coverage area AB is less than the predetermined time.

(Second Judgment Department)
The second determination unit 213 determines whether the quality of radio waves emitted by a plurality of base stations around the target vehicle 3 is equal to or higher than a predetermined value. Note that the server-side control unit 21 does not necessarily have to include the second determination unit 213.

(Specific section)
The identification unit 214 identifies the optimal base station for the target vehicle 3 when the server-side receiving unit 23 receives the various information, based on the various information received by the server-side receiving unit 23 and the database. Specifically, the identification unit 214 calls up a table of information for each vehicle type and lane (see Table 3 above) held by the database D, based on the vehicle ID, lane ID, etc. included in the acquired various information. Then, by referring to the called-up table, the identification unit 214 identifies the base station to switch to when the target vehicle 3 is traveling at a point whose latitude and longitude are included in the acquired various information. Specifically, when the target vehicle 3 is traveling near node N with ID 18 in FIG. 3 toward node N with ID 21 (connected to the base station with PCI 9), the identification unit 214 identifies the base station with PCI 50 as the optimal base station.

As described above, the various information received by the server-side receiving unit 23 according to this embodiment further includes the direction of travel of the target vehicle 3. It has been found that the intensity information received by the vehicle 3 varies depending on the direction of travel of the vehicle 3, even at the same location. Therefore, by including the direction of travel in the various information, the identification unit 214 can identify a more optimal base station. As a result, the server system 2 can cause each target vehicle 3 to switch base stations with greater accuracy. Also, as described above, the various information received by the server-side receiving unit 23 according to this embodiment further includes the vehicle model of the target vehicle 3. The radio wave reception characteristics of the vehicle 3 also vary depending on the vehicle model. Therefore, by including the vehicle model in the various information, the identification unit 214 can identify a more optimal base station. As a result, the server system 2 can cause each target vehicle 3 to switch base stations with greater accuracy.

Furthermore, when the second determination unit 213 determines that the quality of radio waves emitted by one of the multiple base stations is not above a predetermined level, the identification unit 214 identifies a detour route that passes through an area where radio waves from another base station that emits radio waves of a predetermined quality or higher can reach. Specifically, for example, as shown in FIG. 6, when traveling on road R1 that passes through the radio wave range AB of base station (PCI_B) and the second determination unit 213 determines that the quality of radio waves emitted by the target base station (PCI_B) is not above a predetermined level, the identification unit 214 identifies a detour route R2 that passes through the radio wave range AD of base station (PCI_D) that emits radio waves of a predetermined quality or higher. Note that the identification unit 214 does not necessarily have to have the function of identifying this detour route R2.

(Generation part)
The generation unit 215 generates a network policy corresponding to the target vehicle 3 based on the second various information received by the server-side receiving unit 23. Specifically, for example, as shown in FIG. 7 , when the target vehicle 3 travels in an area where expressway R3 and general roads coexist, the generation unit 215 generates a network policy for the target vehicle 3 to travel on expressway R3 (switching in the order of base station (PCI_A) → base station (PCI_B) → base station (PCI_C), but not switching to base station (PCI_D)) based on the second various information (e.g., road shape). Note that the server-side control unit 21 does not necessarily have to include this generation unit 215.

(Transmission control section)
As shown in FIG. 4 , the transmission control unit 216 controls the transmission control unit 216 so that the server-side transmission unit 24 transmits to the target vehicle 3 a connection instruction to the base station identified by the identification unit 214 .

In addition, when the determination unit 212 determines that the switching-unnecessary condition is met, the transmission control unit 216 controls the server-side transmission unit 24 so that the server-side transmission unit 24 does not transmit to the target vehicle 3 a connection instruction to the base station identified by the identification unit 214. In this way, when the switching-unnecessary condition is met, the target vehicle 3 does not receive a connection instruction from the base station. As a result, the target vehicle 3 does not have to switch base stations unnecessarily, which further reduces the processing load.

The transmission control unit 216 also controls the server-side transmission unit 24 so that it transmits information regarding the detour route R2 identified by the identification unit 214 to the target vehicle 3. In this way, the server system 2 transmits information regarding the detour route R2 to the target vehicle 3. Therefore, the target vehicle 3 (and the communication devices carried by the occupants) that receives the information can always communicate using radio waves of a predetermined quality or higher by passing through the detour route R2.

The transmission control unit 216 also controls the server-side transmission unit 24 to transmit the network policy generated by the generation unit 215 to the target vehicle 3. When vehicle 3 is traveling on expressway R3, which is parallel to a general road that passes through an area where multiple radio wave spheres overlap, as shown in FIG. 7, the server system 2 may mistakenly recognize that vehicle 3 is traveling on a general road, and the identification unit 214 may identify a base station (PCI_D) away from expressway R3 as the base station to switch to. However, by generating a network policy with the generation unit 215, when the target vehicle 3 is traveling on a specific road or in a specific district, the network policy corresponding to the target vehicle 3 is transmitted to the target vehicle 3. This allows the target vehicle 3 to communicate using a network policy suitable for traveling on a specific road or district.

[Server systems and others]
As shown in FIG. 8 , the server system 2 may include a first server 2a having a server-side storage unit 22 and a second server 2b having a server-side receiving unit 23, an identifying unit 214, and a server-side transmitting unit 24. In this case, the first server 2a includes a second transmitting unit 25 for transmitting data from the database D to the second server 2b. The reception control unit 211 of the second server 2b controls the server-side receiving unit 23 to receive data from the first server 2a, in addition to receiving various information from the vehicle 3. This configuration reduces installation costs when multiple second servers 2b are provided and installed in different regions, compared to when multiple server systems 2 each with an integrated server-side storage unit 22 are installed in each region. The server system 2 may also function as a database creation device. (The server-side control unit 21 may include components corresponding to the device-side acquiring unit 111 and creating unit 112 of the database creation device 1.) When the system is divided into a first server 2a and a second server 2b, the first server 2a may be the database creation device 1 described above.

[vehicle]
Next, a specific configuration of the vehicle 3 that constitutes the communication system 100 will be described. FIG. 9 is a block diagram showing the functional configuration of the vehicle 3.

As shown in FIG. 9, the vehicle 3 includes a vehicle-side control unit 31, a detection unit 32, a vehicle-side transmission unit 33, and a vehicle-side reception unit 34 (second reception unit).

[Detection unit]
The detection unit 32 detects the position of the vehicle 3 and generates position information. The detection unit 32 generates the position information every time a predetermined time period elapses. The detection unit 32 according to this embodiment is configured with, for example, a GPS receiver.

[Vehicle-side transmitter]
The vehicle-side transmitter 33 wirelessly transmits various data, various signals, etc. to the server system 2 or other devices X. The vehicle-side transmitter 33 according to this embodiment is configured by a communication module.

[Vehicle side receiving unit]
The vehicle-side receiving unit 34 wirelessly receives various data, various signals, etc. from the server system 2 or another device X. The vehicle-side receiving unit 34 according to this embodiment is configured as a communication module. Note that the vehicle-side receiving unit 34 may be integrated with the vehicle-side transmitting unit 33 as a vehicle-side communication unit.

[Vehicle-side control unit]
The vehicle-side control unit 31 includes a vehicle-side acquisition unit 311 , a transmission control unit 312 , a reception control unit 313 , and a connection unit 314 .

(Vehicle side acquisition unit)
The vehicle-side acquisition unit 311 acquires the position information generated by the detection unit 32. Furthermore, every time the detection unit 32 generates position information, the vehicle-side acquisition unit 311 acquires the position information.

(Transmission control section)
The transmission control unit 312 controls the vehicle-side transmission unit 33 so that the vehicle-side transmission unit 33 transmits various pieces of information including the location information acquired by the vehicle-side acquisition unit 311 to the server system 2. Note that the transmission control unit 312 may also be configured to control the vehicle-side transmission unit 33 so that the vehicle-side transmission unit 33 transmits the various pieces of information to the database creation device 1.

(Reception control section)
The reception control unit 313 controls the vehicle-side receiving unit 34 so that the vehicle-side receiving unit 34 receives, from the server system 2 , an instruction to connect to the base station identified by the server system 2 .

(Connection)
The connection unit 314 connects to the base station in response to the connection instruction received by the vehicle-side receiving unit 34 .

[Communication system effects]
According to the communication system 100 according to the present embodiment described above, the optimum base station is identified by the server system 2, not by the vehicle 3. This reduces the load on the target vehicle 3 when determining the base station to switch to.
Furthermore, the server system 2 identifies the base station to which each target vehicle 3 should switch, faster and more accurately than when using the computer resources of the target vehicle 3. Therefore, the target vehicle 3 connected to the server system 2 can stably communicate between the base station and the vehicle simply by having the function of acquiring information from the server system 2. As a result, each target vehicle 3 can switch the base station to which it connects with a certain degree of accuracy, regardless of differences in performance.

[Communication systems and others]
The communication system 100 does not necessarily have to include the database creation device 1 .

Furthermore, some or all of the functions of the control blocks can be realized by logic circuits. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is included in the scope of the present invention. In addition, the functions of the control blocks can also be realized by, for example, a quantum computer.

[Software implementation example]
The functions of each of the devices 1 to 3 constituting the communication system 100 can be realized by a program that causes a computer to function as the device, and that causes a computer to function as each control block of the device (particularly each unit included in the device-side control unit 11, server-side control unit 21, and vehicle-side control unit 31). In this case, the devices 1 to 3 include a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The functions described in the above embodiment are realized by executing the program using this control device and storage device. The program may be stored non-transitory on one or more computer-readable storage media. The storage media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

<Database creation method>
Next, another embodiment of the present invention (database creation method) will be described. Fig. 10 is a flowchart showing the flow of the database creation method.

As shown in Figure 10, the database creation method includes an acquisition step S1 and a creation step S2.

(Acquisition step)
In the first acquisition step S1, sets of information for a plurality of time points are acquired into the database creation device 1. The sets of information include at least location information, base station information, and intensity information at one time point.

(Creation steps)
After the information sets are acquired, the process proceeds to the creation step S2, in which the database creation device 1 is used to create a database by storing the multiple information sets acquired in the acquisition step.

[Action and effect]
According to the database creation method described above, when the location information of the switching destination is acquired, it is possible to obtain a database that can search for the most suitable base station for the vehicle 3 at that location.

Furthermore, according to each aspect of the present invention described above, the aforementioned effects can be achieved, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), "Build resilient infrastructure for industry, technology, innovation and infrastructure." The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

100 Communication system 1 Database creation device 11 Device side control unit 111 Device side acquisition unit (acquisition unit)
112 Creation unit 12 Device-side receiving unit 13 Device-side storage unit 2 Server system 21 Server-side control unit 211, 313 Reception control unit 212 Determination unit 213 Second determination unit 214 Identification unit 215 Generation unit 216, 312 Transmission control unit 22 Server-side storage unit (storage unit)
23 Server-side receiving unit (receiving unit)
24 Server-side transmitting unit (transmitting unit)
25 Second transmission unit 2a First server 2b Second server 3 Vehicle (target vehicle)
31 Vehicle-side control unit 311 Vehicle-side acquisition unit 312 Transmission control unit 313 Reception control unit 314 Connection unit 32 Detection unit 33 Vehicle-side transmission unit 34 Vehicle-side reception unit (second reception unit)

Claims (5)

an acquisition step in which the database creation device acquires, for a plurality of points in time, sets of information including at least the position of the vehicle at one point in time, information about a base station that emitted radio waves received by the vehicle when the vehicle was at that position, and the strength of radio waves received by the vehicle when the vehicle was traveling at that position in a direction corresponding to a lane that passes through the position;
a creation step in which the database creation device creates a database by accumulating the plurality of sets of information acquired in the step of acquiring sets of information;
Including,
In the creating step, the database creating device
calculating location information at a third time, which is a time between the first time and the second time and is a time at which base station information is acquired, by linear interpolation based on the location information at the first time and the location information at a second time, which is an acquisition time following the first time;
storing a pair of the location information at the third time and the base station information at the third time in the database;
How to create a database. When the relationship between the first time or the second time and the acquisition time of the base station information satisfies a predetermined condition, in the creation step, the database creation device associates, with the base station information, one of the location information at the first time and the location information at the second time, which is closer to the acquisition time of the base station information, without performing the linear interpolation.
The database creation method according to claim 1 . the database creation device further includes a calculation step of calculating a speed of the vehicle based on position information of at least two points in time acquired in the acquisition step,
In the acquiring step, the database creation device changes a predetermined time until the next position information is acquired in accordance with the calculated speed.
The database creation method according to claim 1 . In the acquiring step, the database creation device acquires a vehicle ID and a lane ID in addition to the location every time a predetermined time elapses;
In the creating step, the database creating device
categorizing the time-based location information and the time-based base station information by vehicle type based on the vehicle ID;
Based on the lane ID, the time-based location information and the time-based base station information classified by vehicle type are further classified by lane.
The database creation method according to claim 1 . In the acquiring step, the database creation device acquires, in addition to the position, an altitude and an accuracy of the position every time a predetermined time elapses;
In the creating step, the database creating device creates the database by storing sets of the position, the altitude, and the accuracy.
The database creation method according to claim 1 .