JP4996999B2 - Wide area communication / direct communication switching system and wide area communication / direct communication switching method - Google Patents

Description

  The present invention is a wide-area communication capable of switching between wide-area communication between an in-vehicle device represented by a car navigation system using a mobile communication network and a portable terminal and direct communication by a communication network represented by a wireless LAN. -It relates to a direct communication switching system and a wide area communication / direct communication switching method.

In recent years, in-vehicle devices have been equipped not only with car navigation systems that perform the original navigation function, but also with other vehicles, pedestrians and other mobile objects, and communication with roadside devices represented by optical beacons and ETC. Technology that prevents accidents with other vehicles, pedestrians, etc. has been developed using the in-vehicle device. For example, in order to prevent a pedestrian accident, a wide-area communication function capable of communicating with a mobile terminal possessed by a pedestrian using a mobile communication network and a direct communication function capable of performing direct communication using a wireless LAN function are conceivable. Communication between an in-vehicle device having a wireless LAN function and a portable terminal is performed according to the IEEE 802.11 procedure (see, for example, Patent Document 1).
JP 2006-332863 A

  By the way, when an accident prevention service between a vehicle and a traffic weak person such as a pedestrian or a bicycle is assumed, the communication environment deteriorates when communication is performed between the vehicle and a mobile terminal held by the pedestrian or the like. If the wireless LAN connection procedure is changed from a communication failure state to a state where communication can be performed again, the distance between the vehicle and the mobile terminal will approach even while the communication failure occurs. Providing urgent information such as the presence of pedestrians and the risk of collision with pedestrians may be delayed.

  The present invention has been made in view of such problems, and a wide-area communication / direct communication switching system and wide-area communication / direct communication capable of simplifying an operation procedure during direct communication between a vehicle-mounted device and a portable terminal via a wireless LAN. An object is to provide a switching method.

In the wide area communication / direct communication switching system of the present invention, the management means for managing the position information transmitted from the mobile terminal device and the in-vehicle device in the wide area communication via the mobile communication network, and the mobile terminal device and the in-vehicle device directly A server apparatus having a determination unit that determines whether or not communication is possible, and the position information of the own apparatus is transmitted to the server apparatus by wide area communication, and communicates with the mobile terminal apparatus by wide area communication or direct communication. An in-vehicle device having communication control means for performing communication, and a mobile terminal device having communication control means for transmitting position information of the own device to the server device by wide area communication and communicating with the in-vehicle apparatus by wide area communication or direct communication , comprising a said server device, when the portable terminal apparatus and said onboard device has determined that the positional relationship can communicate directly, the mobile Transmitting the position information of the terminal device to the vehicle-mounted device, the vehicle-mounted device receiving the position information of the portable terminal device from the server device in a state of performing communication with the portable terminal device by wide area communication, When requesting direct communication with a terminal device, the server device requests a predetermined parameter required for direct communication with the mobile terminal device, and when the predetermined parameter is requested from the in-vehicle device, The predetermined parameter is set and transmitted to the portable terminal device. After the predetermined parameter is transmitted, a connection request is transmitted to the in-vehicle device, and the portable terminal device that has received the predetermined parameter and the connection request are transmitted. The received in-vehicle device communicates with the on-board device directly .

  According to this configuration, the in-vehicle device and the mobile terminal device periodically transmit location information to the server device, the server device receives and manages the location information, and the in-vehicle device and the mobile terminal device establish a mobile communication network. If the positional relationship is such that direct communication can be performed during wide-area communication using it, the position information of the mobile terminal device is transmitted to the in-vehicle device. When there is a request for a parameter for directly communicating with the mobile terminal device from the in-vehicle device, the parameter is transmitted to the mobile terminal device, and a connection request and a connection request response are exchanged with the in-vehicle device. Then, direct communication is started between the in-vehicle device and the mobile terminal device. Thus, since the server device takes over most of the operation procedure performed between the in-vehicle device and the portable terminal device when switching from wide area communication using the mobile communication network to direct communication, the in-vehicle device and the portable terminal device It is possible to start the direct communication with the client in a short time.

  The wide area communication / direct communication switching system according to the present invention includes the position of the mobile terminal device and the in-vehicle device while the in-vehicle device and the mobile terminal device perform wide-area communication using the mobile communication network in the server device. The positional relationship in which direct communication can be performed is determined from the position of the vehicle that performs direct communication. When direct communication is enabled, predetermined information is given to the in-vehicle device and the mobile terminal device, and Enables direct communication. For this reason, even when the communication environment deteriorates and communication can be resumed from the communication failure state, direct communication between the in-vehicle device and the mobile terminal device can be started in a short time, so that the vehicle side Urgent information such as the presence of pedestrians and the risk of collision with pedestrians can be provided quickly.

  In the present invention, the server device manages position information transmitted from the mobile terminal device and the in-vehicle device by wide-area communication via the mobile communication network. In the server device, the mobile terminal device and the in-vehicle device directly It is determined whether or not communication is possible, and the server device transmits a predetermined parameter to the portable terminal device when the portable terminal device and the in-vehicle device are in a positional relationship that allows direct communication. At the same time, a connection request is transmitted to the in-vehicle device, and the in-vehicle device that has received the connection request and the mobile terminal device that has received the predetermined parameter communicate directly.

  In the wide area communication / direct communication switching system of the present invention, the predetermined parameter includes at least an IP address of the portable terminal device, an IP address of the in-vehicle device, a channel for communication in a wireless LAN, and an identifier of an access point. It is preferable that

  The wide area communication / direct communication switching method of the present invention includes a step of managing position information transmitted from a mobile terminal device and an in-vehicle device in wide area communication via a mobile communication network in the server device, When determining whether or not the terminal device and the in-vehicle device are in a positional relationship in which direct communication is possible, and when the portable terminal device and the in-vehicle device are in a positional relationship in which direct communication is possible, the server device A step of transmitting a predetermined parameter to the mobile terminal device and transmitting a connection request to the in-vehicle device, and a direct communication between the in-vehicle device receiving the connection request and the mobile terminal device receiving the predetermined parameter And the step of performing.

  According to this method, the in-vehicle device and the mobile terminal device periodically transmit location information to the server device, the server device receives and manages the location information, and the in-vehicle device and the mobile terminal device establish a mobile communication network. If the positional relationship is such that direct communication can be performed during wide-area communication using it, the position information of the mobile terminal device is transmitted to the in-vehicle device. When there is a request for a parameter for directly communicating with the mobile terminal device from the in-vehicle device, the parameter is transmitted to the mobile terminal device, and a connection request and a connection request response are exchanged with the in-vehicle device. Then, direct communication is started between the in-vehicle device and the mobile terminal device. Thus, since the server device takes over most of the operation procedure performed between the in-vehicle device and the portable terminal device when switching from wide area communication using the mobile communication network to direct communication, the in-vehicle device and the portable terminal device The operation procedure at the start of direct communication can be simplified.

  In the wide area communication / direct communication switching method of the present invention, the predetermined parameter includes at least an IP address of the mobile terminal device, an IP address of the in-vehicle device, a channel for communication in a wireless LAN, and an identifier of an access point. It is preferable that

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration for explaining a wide area communication / direct communication switching system according to an embodiment of the present invention. The system shown in FIG. 1 is connected to a mobile terminal 1, a vehicle equipped with a car navigation system 3 connected to the mobile terminal 1 via a mobile communication network 2, and a mobile terminal 1 to the mobile communication network 2. The server apparatus 4 is mainly configured. Here, communication using a wireless LAN is used as direct communication.

  The mobile terminal 1 is equipped with a GPS (Global Positioning System), can measure the position of its own device by GPS, and periodically transmits position information to the server device 4. In addition, the mobile terminal 1 can transmit and receive information to and from the car navigation system 3 and the server device 4 via the mobile communication network 2. Further, the mobile terminal 1 can communicate with other mobile terminals via the mobile communication network 2 and can communicate with other computers via the mobile communication network 2 and the Internet. In addition, the mobile terminal 1 is equipped with a wireless LAN, and can directly communicate with the car navigation system 3. When performing direct communication with the car navigation system 3, parameters for performing direct communication from the server device 4 (IP address of the portable terminal 1, IP address of the car navigation system 3, channels for communication in the wireless LAN, and access points) SSID which is an identifier) is transmitted. The mobile terminal 1 has an operating system (mobile device OS), and a browser function, a viewer function, a JAM (Java (registered trademark) Application Manager) and other functions operate on the mobile device OS.

  The mobile communication network 2 is a network between the mobile terminal 1, the car navigation system 3, and the server device 4. The mobile communication network 2 includes a mobile packet communication network in addition to a normal mobile communication network.

  The car navigation system 3 transmits the position information of the host vehicle to the server device 4. The car navigation system 3 is equipped with a wireless LAN and can directly communicate with the portable terminal 1. When the car navigation system 3 receives the position information of the mobile terminal 1 transmitted from the server device 4 and directly communicates with the mobile terminal 1 from the received position information, the car navigation system 3 requests the above parameters from the server device 4. To do. The requested parameter is transmitted to the mobile terminal 1.

  The server device 4 manages the position information of the mobile terminal 1 that provides the service and the position information of the vehicle including the car navigation system 3 that provides the service, and the mobile device 1 that can directly communicate with the car navigation system 3 The position information of the mobile terminal 1 is extracted and transmitted to the car navigation system 3. The server device 4 has a DHCP function, and when the car navigation system 3 and the mobile terminal 1 directly communicate with each other via a wireless LAN, an IP address is assigned to each of the car navigation system 3 and the mobile terminal 1.

  When the mobile terminal 1 and the car navigation system 3 can directly communicate with each other, the server device 4 transmits the position information of the mobile terminal 1 to the car navigation system 3. When the car navigation system 3 receives the position information of the mobile terminal 1 and desires direct communication with the mobile terminal 1, the server device 4 requests the above-described parameters. In addition, an IP address is assigned to each of the car navigation system 3 and a channel used for direct communication between the mobile terminal 1 and the car navigation system 3 and an SSID that is an identifier of the access point are determined and transmitted to the mobile terminal 1.

  In such a system, the server device 4 determines whether or not the car navigation system 3 and the mobile terminal 1 can communicate directly based on the position of the mobile terminal 1 and the position of the vehicle on which the car navigation system 3 is mounted. If direct communication is possible, the position information of the portable terminal 1 is transmitted to the car navigation system 3. After transmitting the position information of the portable terminal 1 to the car navigation system 3, when the car navigation system 3 requests the server device 4 for parameters used for direct communication with the portable terminal 1, the server device 4 The parameter used for the direct communication with 1 is transmitted to the portable terminal 1.

  As described above, the mobile terminal 1 and the car navigation system 3 can directly communicate with each other in a state where the mobile terminal 1 and the car navigation system 3 perform wide-area communication using the mobile communication network 2. When direct communication with the portable terminal 1 is desired, switching from the wide area communication to the direct communication is performed, and at this time, most of the operation procedure at the time of the direct communication is performed by the server device 4. The system 3 can communicate directly in a short time.

  FIG. 2 is a block diagram showing a schematic configuration of the mobile terminal 1 shown in FIG. Note that the configuration shown in FIG. 2 is simplified for the purpose of describing the present invention, and is assumed to include components mounted on a normal mobile terminal.

  The mobile terminal 1 includes a control unit 11 that controls the entire device, a communication control unit 12 that communicates with the car navigation system 3 and the server device 4 via the mobile communication network 2, and an input unit that inputs various data. 13, a display unit 14 that displays various data and position information, a GPS device 15 that measures the position of the device itself, and an application control unit 16 that is installed in the device or activates various downloaded applications. It is mainly composed.

  The communication control unit 12 transmits the position information of the own device to the server device 4 and receives the parameters described above from the server device 4. In addition, after receiving a parameter for performing direct communication, when there is a connection request from the server device 4, the communication control unit 12 makes a connection request response and starts a connection with the car navigation system 3. A communication protocol such as TCP / IP is used for this communication.

  The GPS device 15 detects the current position (latitude, longitude) of the mobile terminal 1 with a predetermined accuracy using a GPS satellite (not shown). The GPS device 15 outputs the measured position information to the display unit 14. The application control unit 16 activates a communication switching application that is mounted on the device or downloaded. The communication switching application for the portable terminal 1 transmits the position information of the own device to the server device 4, and when a parameter for performing direct communication is transmitted from the server device 4, the parameter is received and received. It recognizes the IP address of its own device, the IP address of the car navigation system 3 from the parameters, the channel used for direct communication, and the SSID that is the identifier of the access point, and connects to the car navigation system 3 based on the recognized parameters. It is an application to start.

  FIG. 3 is a block diagram showing a schematic configuration of the car navigation system 3 shown in FIG. Note that the configuration shown in FIG. 3 is simplified for the purpose of describing the present invention, and it is assumed that the components mounted on a normal vehicle-mounted device are provided. This in-vehicle device is composed of a car navigation system and a communication device.

  The car navigation system 3 displays a control unit 31 that controls the entire device, a communication control unit 32 that communicates with the mobile terminal 1 and the server device 4 via the mobile communication network 2, and displays various data and information. The display unit 33, the GPS device 34 that measures the position of the device itself, and the application control unit 35 that activates various applications installed or downloaded in the device.

  The communication control unit 32 transmits the position information of the own device to the server device 4 when the communication switching application is activated. The GPS device 34 detects the current position (latitude, longitude) of the car navigation system 3 with a predetermined accuracy using a GPS satellite (not shown).

  The application control unit 35 activates a communication switching application that is mounted on the device or downloaded. When the communication switching application of the car navigation system 3 transmits the position information of its own device to the server device 4 and the position information of the portable terminal 1 is transmitted from the server device 4 and directly communicates with the portable terminal 1, Request the server device 4 for the IP address of the portable terminal 1, the IP address of the own device, the channel used for direct communication, and the SSID that is the identifier of the access point, and then send a connection request response to the connection request from the server device 4. After returning, the application starts connection with the mobile terminal 1.

  FIG. 4 is a block diagram showing a schematic configuration of the server device 4 shown in FIG. The configuration shown in FIG. 4 is simplified for explaining the present invention, and it is assumed that the components mounted on the normal server device are provided.

  The server device 4 includes a control unit 41 that controls the entire device, a communication control unit 42 that communicates with the mobile terminal 1 and the car navigation system 3 via the mobile communication network 2, and a mobile terminal for each specific area. It is determined whether or not the area information database (DB) 43 that manages the position of 1 and the position of the vehicle on which the car navigation system 3 is mounted and the portable terminal 1 and the car navigation system 3 are in a positional relationship that allows direct communication. The determination unit 44 and an application control unit 45 that activates various applications that are installed in or downloaded from the apparatus.

  The communication control unit 42 receives the position information of the mobile terminal 1 and the car navigation system 3 and transmits the position information of the mobile terminal 1 to the car navigation system 3 when the communication switching application is activated.

  The area information DB 43 is a database that manages the position of the mobile terminal 1 and the position of the vehicle on which the car navigation system 3 is mounted in a specific area. The area information DB 43 has a management table as shown in FIG. In the management table shown in FIG. 5, in a specific area (area A), the mobile terminal (terminal 001, terminal 003) and the in-vehicle devices (in-vehicle device 011, in-vehicle device 012, in-vehicle device 015) are stored in positional information (latitude, (Longitude). In the area information DB 43, attribute information and identification information are included in the information sent from the mobile terminal 1 and the car navigation system 3, and such attribute information and identification information are also managed. Note that the management items and management methods in the management table shown in FIG. 5 are not limited to this, and various changes can be made. As shown in FIG. 5, the area information DB 43 manages the position of the mobile terminal 1 and the position of the vehicle on which the car navigation system 3 is mounted in a specific area while sequentially updating it.

  The determination unit 44 determines whether or not there is a positional relationship in which both can directly communicate using the position information sent from the mobile terminal 1 and the car navigation system 3. In this case, for example, the determination can be made by measuring the distance between the portable terminal 1 and the car navigation system 3 and making a threshold determination with respect to the distance. That is, if the distance between the two is equal to or less than a predetermined threshold, it is determined that both can communicate directly.

  The application control unit 45 activates a communication switching application installed in the device or downloaded. The communication switching application for the server device 4 manages position information from the mobile terminal 1 and the car navigation system 3, transmits the position information of the mobile terminal 1 to the car navigation system 3, and the mobile terminal 1 from the car navigation system 3. If there is a request for a parameter as described above, the parameter is set and transmitted to the mobile terminal 1, and after the parameter is transmitted, a connection request is made to the car navigation system 3 and a connection request is made to the car navigation system. 3 is an application that receives a connection request response transmitted from 3.

Next, the wide area communication / direct communication switching method according to the embodiment of the present invention will be described with reference to FIG.
In the wide area communication / direct communication switching method of the present invention, the server device 4 uses the mobile terminal 1 and the car navigation system 3 based on the location information transmitted from the mobile terminal 1 and the car navigation system 3 by wide area communication using the mobile communication network 2. If the position of the vehicle on which the navigation system 3 is mounted is managed, it is determined whether the portable terminal 1 and the car navigation system 3 are in a positional relationship that allows direct communication using a wireless LAN, and direct communication is possible. For example, the position information of the portable terminal 1 is notified to the car navigation system 3, and it is determined whether or not the car navigation system 3 has requested a parameter necessary for direct communication using the wireless LAN with the portable terminal 1. When requested, the parameter is given to the portable terminal 1, and then the car navigation system is used using a wireless LAN. The car navigation system 3 periodically measures the position of the vehicle and notifies the server apparatus 4 of the position information of the vehicle. The server apparatus 4 notifies the position information of the portable terminal 1. In the case of direct communication with the mobile terminal 1, the server device 4 is requested for parameters for performing direct communication by wireless LAN, and then a connection request response is made to the connection request from the server device 4. After that, direct communication using the wireless LAN is performed with the mobile terminal 1, the mobile terminal 1 periodically measures the position of its own device, and notifies the server device 4 of the location information. Direct communication with the car navigation system 3 is performed in accordance with a communication protocol such as TCP / IP, using the assigned parameters for direct communication with the wireless LAN.

  A communication switching application is activated in each of the application control units 16, 35, and 45 of the mobile terminal 1, the car navigation system 3, and the server device 4, and the mobile terminal 1 and the car navigation system 3 use the mobile communication network 2. The following operations will be described assuming that the communication is in the wide area communication.

  The portable terminal 1 and the car navigation system 3 periodically transmit position information to the server device 4 (ST11, ST12). In the server device 4, the control unit 41 refers to the area information DB 43, and uses the mobile terminal 1 and the car navigation system from the position information of the mobile terminal 1 that uses this service and the position information of the vehicle on which the car navigation system 3 is mounted. 3 determines whether direct communication is possible (ST13). If the mobile terminal 1 and the car navigation system 3 can communicate directly, the location information of the mobile terminal 1 is transmitted to the car navigation system 3 using this service via the communication control unit 42 (ST14). The car navigation system 3 receives the position information of the mobile terminal 1 via the communication control unit 32.

  When the car navigation system 3 using this service receives the location information of the mobile terminal 1, the parameters for directly communicating with the mobile terminal 1 (IP address of the mobile terminal 1, IP address of the car navigation system 3, mobile terminal 1) And a signal requesting a channel and SSID used for direct communication with the car navigation system 3 are transmitted to the server device 4 via the communication control unit 32 (ST15). When the server device 4 receives the parameter request from the car navigation system 3, the server device 4 sets parameters necessary for direct communication between the car navigation system 3 and the mobile terminal 1, and the mobile terminal 1 via the communication control unit 42. (ST16).

  Next, the server device 4 makes a connection request to the car navigation system 3 using the wireless LAN (ST17). When the car navigation system 3 using this service receives a connection request from the server device 4, it transmits a connection request response to the server device 4 via the communication control unit 32 (ST18). Thereby, the portable terminal 1 using this service starts connection with the car navigation system 3 using a communication protocol such as TCP / IP (ST19).

  Thus, in the wide area communication / direct communication switching system according to the present embodiment, the server device 4 constantly monitors the position information of the mobile terminal 1 and the car navigation system 3, and the mobile terminal 1 and the car navigation system 3 move. When the mobile terminal 1 and the car navigation system 3 can communicate directly with each other in a state where wide-area communication is performed using the communication network 2, the car navigation system 3 is notified of the location information of the mobile terminal 1, When there is a request for parameters (IP address, channel and SSID) required for the wireless LAN from the car navigation system 3 by this notification, the parameters are set and given to the mobile terminal 1, and the mobile terminal 1 and the car navigation system 3 Communication between the mobile terminal 1 and the car navigation system. Since the server device 4 takes over most of the operation procedures performed between the system 3 and the direct communication with the system 3 to enable direct communication between the portable terminal 1 and the car navigation system 3, it is possible to Switching to direct communication can be performed in a short time.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. For example, in the above embodiment, the case where a wireless LAN is used for direct communication has been described. However, in the present invention, a communication method other than the wireless LAN may be used for direct communication. Moreover, unless it deviates from the scope of the present invention, the processing unit and the processing procedure can be appropriately changed and implemented. Other modifications can be made without departing from the scope of the present invention.

1 is a diagram showing a schematic configuration of a wide area communication / direct communication switching system according to an embodiment of the present invention. It is a block diagram which shows schematic structure of the portable terminal in the system shown in FIG. It is a block diagram which shows schematic structure of the vehicle-mounted apparatus in the system shown in FIG. It is a block diagram which shows schematic structure of the server apparatus in the system shown in FIG. It is a figure which shows the example of the management table in the area information database of a server apparatus. It is a sequence diagram for demonstrating the wide area communication and direct communication switching method which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile terminal 2 Mobile communication network 3 Car navigation system 4 Server apparatus 11, 31, 41 Control part 12, 32, 42 Communication control part 13 Input part 14, 33 Display part 15, 34 GPS apparatus 16, 35, 45 Application control part 43 Area information DB
44 judgment part

Claims (4)

Management means for managing position information transmitted from the mobile terminal device and the in-vehicle device in wide area communication via a mobile communication network, and whether or not the mobile terminal device and the in-vehicle device are in a positional relationship capable of direct communication. A server device having determination means for determining;
An in-vehicle device having communication control means for transmitting the position information of the own device to the server device by wide-area communication and communicating with the portable terminal device by wide-area communication or direct communication;
A mobile terminal device having communication control means for transmitting the position information of the own device to the server device by wide area communication and communicating with the in-vehicle device by wide area communication or direct communication;
Equipped with,
When the server device determines that the portable terminal device and the in-vehicle device are in a positional relationship in which direct communication is possible, the server device transmits position information of the portable terminal device to the in-vehicle device,
When the in-vehicle device receives position information of the mobile terminal device from the server device and performs direct communication with the mobile terminal device while performing communication with the mobile terminal device by wide area communication, the mobile terminal device Request the server device for predetermined parameters required for direct communication with the server,
When the predetermined parameter is requested from the in-vehicle device, the server device sets the predetermined parameter and transmits the set parameter to the portable terminal device. After the predetermined parameter is transmitted, the server device transmits a connection request to the in-vehicle device. Send
A wide area communication / direct communication switching system , wherein the portable terminal device that has received the predetermined parameter and the in-vehicle device that has received the connection request communicate by direct communication.   2. The wide area according to claim 1, wherein the predetermined parameter is at least an IP address of the mobile terminal device, an IP address of the in-vehicle device, a communication channel in a wireless LAN, and an SSID that is an identifier of an access point. Communication / direct communication switching system. Server device, and a step of managing location information transmitted from the portable terminal device and the in-vehicle device in a wide area communications over the mobile communication network, said server apparatus, said portable terminal device and said vehicle devices can communicate directly Determining whether there is a proper positional relationship;
Wherein when the portable terminal apparatus and said onboard device has determined that the positional relationship can communicate directly, the server device, and transmitting the location information of the mobile terminal device to the vehicle device,
When the in-vehicle device receives position information of the mobile terminal device from the server device and performs direct communication with the mobile terminal device while performing communication with the mobile terminal device by wide area communication, the mobile terminal Requesting the server device for predetermined parameters required for direct communication with the device;
When the predetermined parameter is requested from the in-vehicle device, the server device sets the predetermined parameter and transmits it to the mobile terminal device, and transmits a connection request to the in-vehicle device after transmitting the predetermined parameter. And a process of
A wide area communication / direct communication switching method comprising: a step of performing communication by direct communication between the mobile terminal device that has received the predetermined parameter and the in-vehicle device that has received the connection request .   4. The wide area according to claim 3, wherein the predetermined parameter is at least an IP address of the mobile terminal device, an IP address of the in-vehicle device, a channel for communication in a wireless LAN, and an SSID that is an identifier of an access point. Communication / direct communication switching method.

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