JP5679928B2 - Data transmission system - Google Patents

Description

  The present invention relates to a data transmission system that transmits and receives content data of an in-vehicle device using a wireless device.

  With the spread of in-vehicle devices (car navigation systems, etc.), the amount of data required for maps, music, videos, etc. is increasing. There are storage media such as an HDD and a memory for storing data. However, when the amount of data to be stored increases, a storage medium having a large capacity is required. On the other hand, by using an in-vehicle wireless device, information can be obtained without largely depending on a storage medium. As an information distribution method using such a wireless device, for example, there are methods shown in Patent Documents 1 and 2.

  Patent Document 1 discloses an information distribution device that distributes information according to the urgency of information. In this apparatus, first, the priority is determined from the desired distribution end time of the content to be downloaded, the average communication speed of the wireless device, and the content data amount. Next, the bandwidth and channel to be allocated are determined from the determined priority, and the content is transmitted.

  Patent Document 2 discloses an information communication apparatus that schedules the order of downloading various requested contents. In this device, first, the data size of multiple contents is calculated from the radio wave environment of the travel route of the vehicle, the data size of the requested content, and the vehicle speed information, and the download is possible in the communicable band according to the data size and the download request start point. Calculate and compare different data sizes. Based on the comparison result, optimal scheduling is performed.

JP 2003-348630 A JP 2004-282456 A

  Conventionally, as described above, the technology for transmitting and receiving content data that will be required for an in-vehicle device via a network using a wireless device is as follows. In other words, the bandwidth to be allocated is determined from the determined priority, and (2) optimal scheduling of download in the communicable bandwidth is performed.

  However, conventionally, the amount of data already stored in the in-vehicle device and the amount of data to be stored are not considered, and there is a point to be solved from the viewpoint of suppressing the amount of data stored in the in-vehicle device. That is, in the past, the amount of data to be uniformly downloaded was determined regardless of the amount of data already stored in the in-vehicle device and the amount of data to be stored. Considering the amount of data to be retained, the capacity of the storage device mounted on the vehicle-mounted device can be further reduced than before. As described above, there is room for reducing the amount of data stored in the in-vehicle device, but the solution has not been realized.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a data transmission system that can reduce the capacity of a storage device mounted on an in-vehicle device.

Data transmission system according to the present invention, in the data transmission system which performs data distributed to the vehicle-mounted device via the access point, together with a map to the map data transmittable area corresponding to the position of the terminal as the accessible area, the A server that maps the bit rate when the vehicle-mounted device receives data at each point to the map, an access point that determines the bandwidth of data to be distributed to the vehicle-mounted device according to the urgency received from the vehicle-mounted device, and a map From the speed of the vehicle and the speed of the vehicle, the difference between the time until the vehicle passes through the inaccessible area and the time to consume the data received so far is accessible at the access point until reaching the inaccessible area. the value obtained by dividing the bit rate of the area and urgency, and notifies the urgency to the access point vehicle device Comprising a, the access point, the higher the degree of urgency, in which so as to increase the bandwidth of the data delivery to the vehicle device.

  In the data transmission system of the present invention, the difference between the time until the vehicle passes through the inaccessible area and the time for consuming the received data so far is regarded as the urgency, and the higher the urgency, the bandwidth of the data to be distributed Therefore, the amount of data stored in the in-vehicle device can be reduced, and the capacity of the storage device mounted can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the data transmission system by Embodiment 1 of this invention. It is a block diagram which shows the data transmission system by Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a data transmission system according to Embodiment 1 of the present invention.
The data transmission system of FIG. 1 includes a server 100, an access point 200, an in-vehicle device A (300-1), and an in-vehicle device B (300-2).

  The server 100 has a function of mapping an area in which data can be transmitted according to the position of the in-vehicle device A (300-1) and the in-vehicle device B (300-2) as an accessible area to the map, and the in-vehicle device A (300 -1) A map creation processing unit 101 that maps the data (vehicle position, inaccessible area) transmitted from the in-vehicle device B (300-2) to a map and creates the latest accessible situation map is provided. Yes. The access point 200 is a device that distributes data to the in-vehicle device A (300-1) and the in-vehicle device B (300-2), and the in-vehicle device A (300-1) and the in-vehicle device B (300-2). On the basis of the urgency received from the on-vehicle device A (300-1) and on-vehicle device B (300-2), the bandwidth allocation determination processing unit 201 that determines the bandwidth to be allocated, and the bandwidth allocation determination processing unit 201 The information transmission part 202 which transmits data to each vehicle equipment A (300-1) and vehicle equipment B (300-2) with the determined bandwidth is provided.

The in-vehicle device A (300-1) and the in-vehicle device B (300-2) have a function of reproducing a map, music, a video, and the like, and include an information transmission unit 301, an accessible situation map update unit 302, and an urgency level. And a calculation unit 303. The information transmission unit 301 has a function of sending various information of the host vehicle to the server 100 via the access point 200, and the accessible situation map update unit 302 displays the latest accessible situation map transmitted from the server 100. It has a function of receiving and updating a map of the own vehicle. The emergency level calculation unit 303 has a function of calculating the emergency level from the latest accessible situation map and vehicle information such as the vehicle position and speed.
Since the configuration and operation of the in-vehicle device A (300-1) and the in-vehicle device B (300-2) are the same, the illustration of the internal configuration and the description of the operation are represented by the in-vehicle device A (300-1). To do.

Next, the operation of the data transmission system according to the first embodiment will be described.
[Step 1]
The in-vehicle device A (300-1) installed in the vehicle acquires the following information, and the information transmission unit 301 transmits the information to the server 100 (indicated by an arrow 401 in FIG. 1).
・ The position of the vehicle by GPS measurement (vehicle position information)
・ Information on whether or not the access point 200 can be accessed at the vehicle position (accessible information)
Received power / bit rate

  Here, the inaccessible information is information transmitted from the in-vehicle device A (300-1) and the in-vehicle device B (300-2) to the server 100 and mapped by the server 100. The access point 200 and the in-vehicle information It is the information showing the communication state between machine A (300-1) and vehicle equipment B (300-2). This inaccessible information is stored as data when inaccessible, and is transmitted to the server 100 when it becomes accessible.

  In addition, regarding the received power, the power received by the vehicle-mounted device A (300-1) and the vehicle-mounted device B (300-2) is considered to be different for each point on the road. The information is used (the higher the received power intensity, the easier the vehicle-mounted device can receive the information). The bit rate is the bit rate when data is received from the access point 200 by the in-vehicle device A (300-1) and the in-vehicle device B (300-2). The received power and bit rate can be used as inaccessible information, but are not essential.

[Step 2]
The map creation processing unit 101 maps the information in step 1 received by the server 100. That is, the map creation processing unit 101 receives the information transmitted in step 1, and maps the information on the vehicle position and the inaccessible information to the map. A clear map of inaccessible areas can be made from inaccessible information. When mapping, the boundary between the accessible area and the inaccessible area, and 1 and 0 are written to indicate that one side of the boundary is an accessible area and the other is an impossible area. For example, the determination of an accessible area is a road that is sandwiched between 1 and 1, and an inaccessible area is sandwiched between 0 and 0. In addition, when information on received power and bit rate is used, in order to indicate the difference in strength, for example, the strength is divided into four levels: (1) high, (2) medium, (3) small, and (4) none. It is also possible to describe the boundaries as 0 to 3.

  In the data transmission system of the present invention, the server 100 has information on the inaccessible area based on the accessible situation map created in the past, but the in-vehicle device A (300-1) and the in-vehicle device B (300-2). The information on the inaccessible area possessed by the server 100 is updated by the inaccessible information transmitted from the server 100, and the information on the inaccessible area possessed by the server 100 is always updated. Note that the first accessible situation map needs to be given to the server 100.

That is, the inaccessible area is obtained as follows.
(1) While the in-vehicle device is present in the inaccessible area, information that the in-vehicle device cannot access the access point 200 (accessible information) is stored together with the own vehicle position.
(2) When the in-vehicle device enters the accessible area, the in-vehicle device transmits to the server 100 information that the access that has been stored as the inaccessible information cannot be performed.
(3) The server 100 maps the information received in (2) to an accessible situation map, and obtains an inaccessible area on the map.

[Step 3]
The latest accessible state map is transmitted from the server 100 to the in-vehicle device A (300-1) (indicated by an arrow 402 in FIG. 1).
The map creation processing unit 101 transmits a map (the latest accessible situation map) on which the created accessible / inaccessible area is mapped to the vehicle-mounted device A (300-1). The map transmitted here is not a map relating to roads in the entire world, but a minimum map required by the in-vehicle device A (300-1). Here, when a route is set, the minimum map is a map up to an accessible area beyond a location where there is an inaccessible area on the route. If this map is a more detailed map (map zoomed in) than the map displayed by the navigation function in the navigation system (not shown), a map having the size of the map displayed on the navigation screen is transmitted.

  In addition, the minimum map when the route is not set includes the longest accessible area from the location of the vehicle when there is an accessible area beyond the inaccessible area around the vehicle It is a map. If this map is a more detailed map (a zoomed-in map) than the map displayed by the navigation function, a map having the same size as the map displayed on the navigation screen is transmitted.

[Step 4]
In order to reflect the received information about the map in the map of the in-vehicle device A (300-1), the accessible situation map update unit 302 updates the map with the latest accessible situation map. In-vehicle device A (300-1) deletes the map it had so far, and uses the new map received in step 3 thereafter. Also, the latest map is output to the urgency calculator 303 (indicated by an arrow 403 in FIG. 1).

[Step 5]
The urgency level calculation unit 303 performs the following processing to create an urgency level.
The emergency level calculation unit 303 collects vehicle information and calculates an emergency level. In the vehicle information collection, the vehicle speed is collected from the car meter, and the time until the data of each content is consumed from the navigation system. The urgency is calculated as follows. In the data of each content such as music playback, the time until the data currently held in the in-vehicle device A (300-1) is consumed is called data consumption time. In addition, the accessible / inaccessible area is known from the map, and the distance from the vehicle position to the inaccessible area and the distance that the inaccessible area continues are calculated. The inaccessible area time described below can be found from the relationship between the obtained distance and the vehicle speed. The urgency is obtained from the difference between these two times.

-Data consumption time = time until data currently held by the vehicle-mounted device A (300-1) is consumed-Inaccessible area time = When entering the inaccessible area from the current position in a short remaining time Time to enter the next accessible area. Since the distance from the inaccessible area to the next accessible area is known on the map, the time can be obtained by dividing them by the average vehicle speed.

  The urgency level is obtained by the difference between the urgency level = inaccessible area time and the data consumption time (urgent level = inaccessible area time−data consumption time). The higher the degree of urgency, the more data must be sent to the in-vehicle device. In addition, when the boundary between the multi-stage accessible area and the inaccessible area is expressed using the reception power and the bit rate, the inaccessible area time may be obtained in consideration of the multi-stage boundary.

[Step 6]
The urgency level calculation unit 303 transmits the calculated urgency level from the in-vehicle device A (300-1) and is received by the bandwidth allocation determination processing unit 201 of the access point 200 (indicated by an arrow 404 in FIG. 1).

[Step 7]
The access point 200 determines a bandwidth to be allocated to the in-vehicle device A (300-1). In other words, the bandwidth allocation determination processing unit 201 of the access point 200 determines each vehicle-mounted device A (300-1) and vehicle-mounted device B (300-2) based on the urgency value from the vehicle-mounted device A (300-1). The bandwidth allocated to each in-vehicle device is determined according to the degree of urgency. The more in-vehicle devices with higher urgency give a larger bandwidth. The bandwidth information is notified from the bandwidth allocation determination processing unit 201 to the information transmission unit 202 (indicated by an arrow 405 in FIG. 1). The bandwidth value is set so that the data to be transmitted is completed before entering the inaccessible area.

[Step 8]
The information transmission unit 202 of the access point 200 transmits necessary data to each of the in-vehicle devices A (300-1) and B (300-2) with the bandwidth determined by the bandwidth allocation determination processing unit 201. (Indicated by arrow 406 in FIG. 1). The data to be distributed is received from the server 100, but since this flow is publicly known, a description thereof is omitted here.

  As described above, according to the data transmission system of the first embodiment, in a data transmission system that distributes data to an in-vehicle device via an access point, it is possible to access an area in which data can be transmitted according to the position of the in-vehicle device. The vehicle cannot be accessed from the server that maps to the map as an area, the access point that determines the bandwidth of the data distributed to the vehicle-mounted device according to the urgency received from the vehicle-mounted device, and the speed of the map and the vehicle The difference between the time to pass the area and the time to consume the data received so far is the urgency level, and the access point is equipped with an in-vehicle device that notifies the urgency level. Since the bandwidth for data distribution to the aircraft has been increased, data should be transmitted preferentially to in-vehicle devices that require highly urgent data. Data required between the inaccessible area to be pre-transmitted data, the data lack in inaccessible areas is eliminated. As a result, the amount of data to be accumulated from the beginning is reduced, and the size of a storage medium such as an HDD installed can be reduced.

Embodiment 2. FIG.
In the first embodiment, the time required to pass through the inaccessible area for obtaining the degree of urgency is obtained on the in-vehicle device side. However, an example in which the time is obtained on the access point side will be described as the second embodiment.

  FIG. 2 is a configuration diagram illustrating a data transmission system according to the second embodiment. In addition to the configuration of the first embodiment, an inaccessible area passing time calculation unit 203 is added at the access point 200a. The inaccessible area passage time calculation unit 203 is configured to calculate the time required to pass through the inaccessible area in each direction as viewed from the access point 200. The access point 200a is also configured to hold the latest accessible situation map around the access point 200a.

  In addition, in vehicle-mounted device A (300a-1) and vehicle-mounted device B (300a-2), information transmission unit 301a uses the speed of the host vehicle as vehicle information in addition to the configuration of information transmission unit 301 in the first embodiment. It is configured to send. Further, the accessible situation map update unit 302a receives, from the access point 200a, the time necessary to pass through the inaccessible area calculated by the inaccessible area passage time calculation unit 203 together with the latest accessible situation map. It is configured to Moreover, the emergency level calculation unit 303a holds the transit time of the inaccessible area received by the accessible state map update unit 302a and the in-vehicle device A (300a-1) and the in-vehicle device B (300a-2). The difference from the time when data is consumed is regarded as an urgency level, and this is notified to the bandwidth allocation determination processing unit 201 of the access point 200a.

Next, the operation of the second embodiment will be described, but only differences from the operation of the first embodiment will be described.
First, the information transmission part 301a of vehicle equipment A (300a-1) and vehicle equipment B (300a-2) notifies the server 100 also including the speed of the own vehicle. Since the access point 200a receives and holds the latest accessible situation map from the server 100, the access point 200a can know the situation of neighboring inaccessible areas based on this. For each direction from the access point 200a, the inaccessible area passage time calculation unit 203 calculates the time required to pass through the inaccessible area in the vicinity as "distance obtained from the latest accessible situation map". And “average vehicle speed calculated by uploading to the server 100”. The in-vehicle device A (300a-1), based on the inaccessible area passage time calculated by the inaccessible area passage time calculation unit 203, determines an inaccessible area in the vicinity corresponding to the direction in which the vehicle travels. Taking the time required to pass as a reference, the difference between the time spent on the data held in each vehicle-mounted device A (300a-1) and vehicle-mounted device B (300a-2) is taken, and the difference is urgent Degree. That is, the urgency is expressed as follows.
Urgency = time required to pass through an inaccessible area in the vicinity corresponding to the direction in which the host vehicle travels—data consumption time in each vehicle-mounted device A (300a-1) and vehicle-mounted device B (300a-2)

  The bandwidth allocation processing distributed by the bandwidth allocation determination processing unit 201 based on the degree of urgency and the data transmission of the information transmission unit 202 are the same as in the first embodiment. In addition, the latest accessible situation map is transmitted to the in-vehicle device A (300-1) via the inaccessible area passage time calculation unit 203. As long as the inaccessible area transit time is transmitted, it is not always necessary to transmit it every time. In addition, when the boundary between a multi-stage accessible area and an inaccessible area is expressed using the received power and bit rate, the inaccessible area transit time calculation unit 203 considers the multi-stage boundary and performs access. Impossible area time may be obtained.

  As described above, according to the data transmission system of the second embodiment, in a data transmission system that distributes data to an in-vehicle device via an access point, it is possible to access an area in which data can be transmitted according to the position of the in-vehicle device. Based on the server that maps to the map as an area and the speed of the vehicle on which the map and the vehicle-mounted device are mounted, the time required to pass through the inaccessible area near the location of the vehicle-mounted device is calculated, and the calculated pass In addition to transmitting the time to the in-vehicle device, the access point that determines the bandwidth of data to be distributed to the in-vehicle device according to the urgency received from the in-vehicle device, and the transit time of the inaccessible area transmitted from the access point Based on the inaccessible area in the direction the vehicle is traveling, and erase this transit time and the data received by the in-vehicle device so far. As the urgent level is the difference between the time to be used and the in-vehicle device that notifies the urgent level to the access point, the access point increases the bandwidth for data distribution to the in-vehicle device as the urgency level increases. If the “time required to pass through an inaccessible area in the vicinity” is calculated corresponding to the direction in which the host vehicle travels, an effect of reducing the amount of calculation in each in-vehicle device can be expected. Although the road condition varies, it is considered that the position of the inaccessible area is hardly changed. Therefore, the calculation amount is reduced by not calculating the distance as compared with the calculation by each in-vehicle device. As a further effect, it is not necessary to always transmit data relating to the map from the access point to the in-vehicle device, so that an effect that the amount of data to be transmitted can be reduced can be expected.

Embodiment 3 FIG.
In the first and second embodiments described above, the urgency is obtained from the difference between the time for passing through the inaccessible area and the data consumption time. In addition, in the third embodiment, the bit rate that can be actually received for a point in the access point 200 is added to the latest accessible situation map.

  The configuration of the data transmission system according to the third embodiment in the drawing is the same as that in FIG. 1 and will be described using the configuration in FIG. In Embodiment 3, the information transmission part 301 of each vehicle equipment A (300-1) and vehicle equipment B (300-2) transmits the bit rate when data is received to the server 100, and the map of the server 100 The creation processing unit 101 also associates the bit rate at each position on the map. In addition, the accessible status map update unit 302 of the in-vehicle device A (300-1) and the in-vehicle device B (300-2) receives the latest accessible status map mapped including the bit rate, and the urgent level calculation unit 303 is configured to calculate the urgency based on this accessible situation map. Since other configurations are the same as those of the first embodiment, description thereof is omitted here.

As an operation, the following processing is added to the first embodiment, or the processing is replaced.
[Additional processing to Step 1]
The information transmission unit 301 of each in-vehicle device 300 transmits to the server 100 the bit rate when data is received at each point in addition to the data of the vehicle position.

[Additional processing to Step 2]
The map creation processing unit 101 of the server 100 also maps the bit rate to the map. The bit rate is mapped to points every 5 m on the map. Every 5 meters is an example with reference to the full length of an ordinary car, and other distances may be used.

[Step 5 (replace processing)]
The emergency level calculation unit 303 collects vehicle information and calculates an emergency level. In the vehicle information collection, the vehicle speed is collected from the car meter, and the time until the data of each content is consumed from the navigation system. The urgency is calculated as follows. In the data of each content such as music playback, the time until the data currently held by the in-vehicle device A300-1 is consumed is called data consumption time. In addition, the accessible / inaccessible area is known from the map, and the distance from the vehicle position to the inaccessible area and the distance that the inaccessible area continues are calculated. The inaccessible area time described below can be found from the relationship between the obtained distance and the vehicle speed. Furthermore, the urgency calculation unit 303 can calculate the amount of data that can be acquired from the bit rate at each point in the access point through which the vehicle passes until the vehicle exits the access point 200, and can receive the data in the access point 200. The urgency level is calculated including the correct amount. The urgency calculation formula is shown below.
Urgency = (access inaccessible area time−data consumption time) / bit rate The access point 200 uses the urgency obtained from this calculation method, and the in-vehicle device with higher urgency transmits data preferentially. That is, the higher the degree of urgency, the larger the data distribution bandwidth to the in-vehicle device.

In the above example, the method for calculating the degree of urgency is applied to the configuration of the first embodiment, but it can be applied to the second embodiment as well. In this case, the urgent level calculation unit 303a is based on the inaccessible area passage time calculated by the inaccessible area passage time calculation unit 203.
Urgency = (time required to pass through an inaccessible area in the vicinity corresponding to the direction in which the vehicle travels−data consumption time) / urgency is calculated based on the bit rate calculation formula. The rest is the same as in the second embodiment.

  As described above, according to the data transmission system of the third embodiment, in a data transmission system that distributes data to an in-vehicle device via an access point, it is possible to access an area in which data can be transmitted according to the position of the in-vehicle device. A map that maps to the map as an area and maps the bit rate when the in-vehicle device receives data at each point to the map, and the bandwidth of the data that is distributed to the in-vehicle device according to the urgency received from the in-vehicle device The difference between the time until the vehicle passes the inaccessible area and the time to consume the data received so far is reached in the inaccessible area based on the access point to determine the map and the speed of the vehicle The value divided by the bit rate of the accessible area at the previous access point is the urgency, and the access point is urgent As the urgency level is higher, the access point increases the data distribution bandwidth to the in-vehicle device, so the access point is superior or inferior due to the difference in bit rate at each point in the access point. Is eliminated, and the most urgent vehicle-mounted device can be reliably extracted between the vehicle-mounted devices.

  Further, according to the data transmission system of the third embodiment, in the data transmission system that distributes data to the in-vehicle device via the access point, the area in which data transmission according to the position of the in-vehicle device can be performed as an accessible area on the map In addition to mapping, the server that maps the bit rate when the in-vehicle device receives data at each point to the map, and the proximity of the in-vehicle device location based on the map and the speed of the vehicle in which the in-vehicle device is installed are not accessible. Access that calculates the time required to pass through the possible area, transmits the calculated transit time to the in-vehicle device, and determines the bandwidth of data to be distributed to the in-vehicle device according to the urgency received from the in-vehicle device Point and the inaccessible area in the direction the vehicle travels based on the transit time of the inaccessible area sent from the access point. Find the overtime, and divide the difference between this transit time and the time that the in-vehicle device consumes the data received so far by the bit rate of the accessible area at the access point until it reaches the inaccessible area. The access point has an on-vehicle device that notifies the access point of the urgency level, and the access point increases the bandwidth for data distribution to the on-vehicle device as the urgency level increases. The superiority or inferiority due to the difference in bit rate at the point is eliminated, and in addition to the effect of the second embodiment, the effect that the in-vehicle device having the highest urgency level among the in-vehicle devices can be surely extracted is obtained.

  In the present invention, within the scope of the invention, the embodiments can be freely combined, any component of each embodiment can be modified, or any component can be omitted in each embodiment. .

  100 server, 101 map creation processing unit, 200, 200a access point, 201 bandwidth allocation determination processing unit, 202 information transmission unit, 203 inaccessible area passage time calculation unit, 300-1, 300a-1 vehicle-mounted device A, 300- 2,300a-2 Vehicle-mounted device B, 301, 301a Information transmission unit, 302, 302a Accessible status map update unit, 303, 303a Urgency calculation unit.

Claims (2)

In a data transmission system that distributes data to in-vehicle devices via an access point,
A server that maps an area in which data can be transmitted according to the position of the vehicle-mounted device as an accessible area on a map, and maps a bit rate to the map when the vehicle-mounted device receives data at each point;
According to the urgency received from the in-vehicle device, an access point that determines the bandwidth of data to be distributed to the in-vehicle device,
The access point until the vehicle reaches the inaccessible area, based on the difference between the time until the vehicle passes through the inaccessible area and the time for consuming the data received so far, based on the speed of the map and the vehicle. A value obtained by dividing the bit rate of the accessible area in the urgent level, and equipped with an in-vehicle device that notifies the urgent level to the access point,
The access point increases the bandwidth of data distribution to the in-vehicle device as the urgency level is higher. In a data transmission system that distributes data to in-vehicle devices via an access point,
A server that maps an area in which data can be transmitted according to the position of the vehicle-mounted device as an accessible area on a map, and maps a bit rate to the map when the vehicle-mounted device receives data at each point;
Based on the map and the speed of the vehicle on which the vehicle-mounted device is mounted, a time required to pass through an inaccessible area near the position of the vehicle-mounted device is calculated, and the calculated passing time is used as the vehicle-mounted device. And an access point for determining the bandwidth of data to be distributed to the in-vehicle device according to the urgency received from the in-vehicle device,
Based on the pass time of the inaccessible area transmitted from the access point, the pass time of the inaccessible area in the direction in which the vehicle travels is obtained, and the pass time and the data received so far by the in-vehicle device are consumed. An in-vehicle device that divides the difference from the time by the bit rate of the accessible area at the access point until reaching the inaccessible area as an urgency, and notifies the access point of the urgency ,
The access point increases the bandwidth of data distribution to the in-vehicle device as the urgency level is higher.

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