JP2005315625A - Navigation device, information center, and wireless communication media switching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a navigation device, an information center, and a wireless communication media switching method capable of smoothly downloading information.
A navigation device 3 acquires communication effective area information of a plurality of wireless communication media 10 from an information center 2, and when a vehicle reaches a boundary of the communication effective area information of the plurality of wireless communication media 10, It is determined whether or not the wireless communication medium connected by wireless communication is switched to a new wireless communication medium. Therefore, depending on the determination result, even if the wireless communication medium 10 has a high communication speed, the communication connection is not switched. For example, connecting to a wireless communication medium with a narrow communication range prevents a situation in which the number of switching times increases and download communication efficiency decreases.
[Selection] Figure 1

Description

  The present invention relates to a navigation device, an information center, and a wireless communication media switching method.

Conventionally, a seamless information providing system that seamlessly provides various types of information to an in-vehicle device mounted on a vehicle is known. In this system, when the communication environment changes, it is possible to switch to a wireless communication medium that can obtain the best communication environment and receive information without disconnection (see, for example, Patent Document 1). .
JP 2001-144814 A

  However, in the related art, even if the wireless communication medium after connection switching is a narrow communication range, if the best communication environment can be obtained, the connection is switched to the wireless communication medium. For this reason, in the prior art, connection may be continuously performed by connecting to a wireless communication medium having a narrow communication range. As a result of continuous switching, a situation may occur in which the number of times of switching increases and download communication efficiency decreases.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a navigation device, an information center, and a wireless communication media switching method capable of smoothly downloading information. Is to provide.

  The navigation device of the present invention acquires predetermined information from an information center that is a source of information via a wireless communication medium. The navigation device includes a current position detection unit, an effective area acquisition unit, a boundary line calculation unit, and a switching determination unit. The current position detection means detects the current position of the vehicle. Further, the effective area acquisition unit acquires information on the communication effective area for a plurality of wireless communication media from the information center, and the boundary line calculation unit includes the communication effective area of the plurality of wireless communication media acquired by the effective area acquisition unit. The boundary line of the effective communication area of each wireless communication medium is calculated from the information. Further, the switching determination unit acquires information from the boundary line calculation unit and the current position detection unit. Then, the switching determination means determines whether to switch from the wireless communication medium connected by wireless communication to a new wireless communication medium based on the information on the acquired boundary line of the effective communication area and the current position detected by the current position detection means. Judge whether or not.

  According to the present invention, a wireless communication medium that obtains communication effective area information of a plurality of wireless communication media from an information center, obtains a boundary, and performs wireless communication connection based on the boundary of the communication effective area and the current vehicle position. Therefore, it is determined whether or not to switch the communication connection to a new wireless communication medium. For this reason, it is possible to perform communication connection switching control when the vehicle reaches the boundary of the communication effective area and perform communication connection switching control, and depending on the switching determination result, the communication speed may be high. Even if the vehicle enters the communication effective area of the wireless communication medium, it is possible not to switch the communication connection. Thereby, for example, it is possible to prevent a situation in which the communication efficiency of download decreases due to an increase in the number of times of switching due to connection to a wireless communication medium having a high communication speed but a narrow communicable range. Therefore, information can be downloaded smoothly.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of an information distribution system including a navigation device and an information center according to an embodiment of the present invention. As shown in FIG. 1, the information distribution system 1 mainly includes an information center 2 that is a source of information and a navigation device 3 that searches for a route from the current position of the vehicle to the destination.

  The information center 2 wirelessly transmits predetermined information to the navigation device 3 mounted on the vehicle through a wireless communication medium 10 such as a mobile phone network 4, a wireless LAN network 5, and a Bluetooth network 6. The information center 2 wirelessly transmits predetermined information to the navigation device 3 via the first to third base stations 11 to 13 when wirelessly transmitting the predetermined information. Here, the predetermined information corresponds to map information including information such as a new map and a new road, traffic information including traffic jams and construction points, and tourist information around the destination.

  The navigation device 3 includes antennas 31a to 31c. Among these, the mobile phone receiving antenna 31 a receives predetermined information wirelessly transmitted from the information center 2 through the mobile phone network 4 and the first base station 11. The wireless LAN antenna 31b and the Bluetooth antenna 31c receive predetermined information wirelessly transmitted from the information center 2 through the wireless LAN network 5 and the second base station 12, and the Bluetooth network 6 and the third base station 13, respectively. To do.

  The first to third base stations 11 to 13 and the antennas 31a to 31c are not particularly limited to three, and may be four or more. In FIG. 1, the navigation device 3 includes one antenna 31 a to 31 c for each wireless communication medium 10, but the number is not limited to one, and a plurality of wireless communication media 10 are provided by one antenna. May be configured to be able to communicate with each other.

  In such an information distribution system 1, as shown in FIG. 2, predetermined information is acquired while switching the communication connection of the wireless communication medium 10. FIG. 2 is an explanatory diagram showing how the navigation device 3 switches the communication connection of the wireless communication media 10. In the figure, the navigation device 3 acquires predetermined information without disconnection while communicating with a plurality of wireless communication media 10 until the vehicle reaches the destination 101 from the current position 100. That is, the navigation device 3 communicates when one wireless communication medium 10 is in a communication disabled state or is likely to be disconnected, such as when a vehicle leaves the effective communication area of each wireless communication medium 10. Predetermined information is acquired while switching the connection to another wireless communication medium 10 that is or is likely to be able to communicate. Thereby, the navigation apparatus 3 can receive predetermined information without disconnection.

  Specifically, the navigation device 3 is a communication effective area of the Bluetooth network 6 (an area where communication can be effectively performed, for example, inside a circle centered on the latitude and longitude of a certain point, When the boundary point 102 is reached, it is determined whether or not the wireless communication medium 10 to be communicated is switched from the cellular phone network 4 to the Bluetooth network 6. Here, it is assumed that the navigation device 3 switches the communication connection.

  Thereafter, the navigation device 3 determines whether or not to switch the wireless communication medium 10 to be communicated from the Bluetooth network 6 to the mobile phone network 4 at a point where the communication effective area of the Bluetooth network 6 leaves, that is, at the boundary point 103. Thereafter, the navigation device 3 sequentially determines whether or not to switch the communication connection with the wireless communication medium 10 at the boundary points 104, 105, 106, and 107. When the navigation device 3 determines that the communication connection should be switched, the navigation device 3 switches the communication connection of the wireless communication medium 10 and acquires predetermined information without disconnection. Thus, by determining whether the communication connection should be switched, the navigation apparatus 3 can smoothly download predetermined information.

  The mobile phone network 4 has a feature that the communication effective area is wide but the communication speed is low. The wireless LAN network 5 has a communication effective area narrower than that of the mobile phone network 4, but the communication speed is the mobile phone network. It is faster than 4. The Bluetooth network 6 has a feature that the effective communication area is narrower than that of the wireless LAN network 5 but the communication speed is faster than that of the cellular phone network 4. For this reason, the navigation device 3 determines whether the wireless communication media 10 should be switched at the boundary points 102 to 107 in consideration of the characteristics of the wireless communication media 10.

  3A and 3B are configuration diagrams of the navigation device 3 according to the embodiment of the present invention. FIG. 3A shows the overall configuration of the navigation device 3, and FIG. 3B shows a partial detailed configuration of the navigation device 3.

  As shown in FIG. 3A, in addition to the antennas 31a to 31c, the navigation device 3 includes a communication control unit 32, a control unit 33, a wireless communication media switching unit 34, a vehicle guidance unit (current position detection means) 35, A wireless communication media information storage unit 36 and a boundary line calculation unit (boundary line calculation means) 37 are provided.

  The communication control unit 32 performs control related to transmission / reception of information and establishment of communication with each wireless communication medium 10. The control unit 33 controls the entire navigation device 3 using the other units 32 and 34 to 37. When the wireless communication media switching unit 34 receives a command to switch the wireless communication media 10 from the control unit 33, the wireless communication media switching unit 34 instructs the communication control unit 32 to establish communication with the commanded wireless communication media 10. .

  The vehicle guiding section 35 has a so-called car navigation function, and calculates and stores the traveling speed, traveling direction, position information of the destination, and the like. Further, the vehicle guiding unit 35 has a function of detecting the current position of the vehicle, and superimposes the current position of the vehicle on a map displayed on a display unit (not shown) during route guidance. And has a function of presenting to the driver. The wireless communication media information storage unit 36 stores information on the wireless communication media 10 with which the navigation device 3 can communicate. The boundary calculation unit 37 obtains the boundary of each wireless communication medium 10, that is, the outer edge of each communication effective area of the mobile phone network 4, the wireless LAN network 5, and the Bluetooth network 6 in FIG. 2. .

  Here, the information of the wireless communication media 10 stored in the wireless communication media information storage unit 36 may be acquired from the information center 2 at irregular intervals, or acquired at the start of communication with the information center 2, for example. Also good. In addition, the control unit 33 uses, for example, a communication effective area information regarding the wireless communication medium 10 that is within a circle whose diameter is a line connecting the current position and the destination and that is centered on an intermediate point between the current position and the destination. May be acquired and stored in the wireless communication media information storage unit 36.

  The controller 33 will be described in detail with reference to FIG. The control unit 33 includes an effective area acquisition unit (effective area acquisition unit) 331 and a switching determination unit (switch determination unit) 332.

  The effective area acquisition unit 331 acquires communication effective area information for the plurality of wireless communication media 10 from the information center 2. In addition, when the effective area acquisition unit 331 acquires the communication effective area information of the plurality of wireless communication media 10, the effective area acquisition unit 331 transmits the information to the wireless communication media information storage unit 36 and stores the information. In addition, when the effective area acquisition unit 331 acquires the communication effective area information of the plurality of wireless communication media 10, the effective area acquisition unit 331 transmits the information to the boundary line calculation unit 37. Accordingly, the boundary line calculation unit 37 calculates the boundary line of the communication effective area of each wireless communication medium 10 from the communication effective area information of the plurality of wireless communication media 10 acquired by the effective area acquisition unit 331. .

  Based on the boundary line of the effective communication area calculated by the boundary line calculation unit 37 and the current position detected by the vehicle guidance unit 35, the switching determination unit 332 determines whether the wireless communication medium 10 connected by wireless communication is It is determined whether or not to switch the communication connection to the new wireless communication medium 10.

  For example, the switching determination unit 332 stores a predetermined threshold value, and even when passing through a communication effective area of the wireless communication medium 10 having a high communication speed, the area and the guidance route hardly overlap and overlap. If the distance is less than or equal to a predetermined threshold, the wireless communication medium 10 is determined not to be switched. Thereby, this apparatus 3 can prevent the situation where the frequency | count of switching of communication increases, and can download predetermined information efficiently.

  Note that the switching determination unit 332 desirably determines whether or not to switch to the new wireless communication medium 10 with the following configuration, rather than performing the above threshold determination. Specifically, the switching determination unit 332 includes a first information capacity calculation unit (first information capacity calculation unit) 332a, a second information capacity calculation unit (second information capacity calculation unit) 332b, a remaining capacity calculation unit (remaining capacity calculation unit). 332c and an information acquisition determination unit (information acquisition determination means) 332d.

  The first information capacity calculation unit 332a calculates the information capacity of predetermined information that can be acquired when the communication connection is switched to the new wireless communication medium 10. For example, in FIG. 2, the first information capacity calculation unit 332 a obtains a distance from the boundary point 102 to the boundary point 103 when the host vehicle reaches the boundary point 102, and calculates the distance and the throughput of the Bluetooth network 6. From this, the information capacity that can be acquired between the boundary points 102 and 103 is calculated. Similarly, the first information capacity calculator 332a calculates the information capacity that can be acquired between the boundary points 104 and 105, between the boundary points 106 and 107, and the like.

  The second information capacity calculation unit 332b calculates the information capacity of predetermined information that can be acquired when the communication connection to the new wireless communication medium 10 is not switched. For example, in FIG. 2, when the host vehicle reaches the boundary point 102, the second information capacity calculation unit 332b obtains the distance from the boundary point 102 to the boundary point 103, and this distance and the throughput of the mobile phone network 4 From this, the information capacity that can be acquired between the boundary points 102 and 103 is calculated. Similarly, the first information capacity calculation unit 332a also does not switch the wireless communication medium 10 to the wireless LAN network 5 or the Bluetooth network 6 between the boundary points 104 and 105, between the boundary points 106 and 107, and the like. The information capacity that can be acquired by the mobile phone network 4 is calculated.

  The remaining capacity calculation unit 332c calculates the remaining information capacity to be acquired among the predetermined information. In FIG. 2, the navigation device 3 has finished acquiring a certain amount of information until the host vehicle reaches the boundary point 102. Therefore, the remaining capacity calculation unit 332c calculates the remaining information capacity to be acquired by subtracting the already acquired information capacity from the total information capacity of the predetermined information. In addition, the remaining capacity calculation unit 332c calculates the remaining information capacity to be acquired, for example, when the boundary points 104 and 106 are reached, for example.

  Based on the calculation results by the first information capacity calculation unit 332a, the second information capacity calculation unit 332b, and the remaining capacity calculation unit 332c, the information acquisition determination unit 332d may or may not switch to a new wireless communication medium. Thus, it is determined whether or not the remaining amount of predetermined information can be acquired.

  Specifically, in the boundary point 102 of FIG. 2, the information acquisition determination unit 332d includes the information capacity calculated by the first information capacity calculation unit 332a and the remaining information to be acquired calculated by the remaining capacity calculation unit 332c. Enter capacity information. The information acquisition determination unit 332d compares these information capacities, and when the information capacity calculated by the first information capacity calculation unit 332a is larger than the information capacity calculated by the remaining capacity calculation unit 332c, the boundary point It is determined that the remaining amount of predetermined information can be acquired before reaching 103. On the other hand, when the information capacity calculated by the first information capacity calculator 332a is not larger than the information capacity calculated by the remaining capacity calculator 332c, the information acquisition determination unit 332d is predetermined until the boundary point 103 is reached. It is determined that the remaining amount of information cannot be obtained.

  Similarly, the information acquisition determination unit 332d compares the information capacity calculated by the second information capacity calculation unit 332b with the information capacity calculated by the remaining capacity calculation unit 332c until the boundary point 103 is reached. It is determined whether or not the remaining amount of predetermined information can be acquired.

  Then, the switching determination unit 332 determines whether to switch the communication connection from the currently communicating wireless communication medium 10 to the new wireless communication medium 10 according to the determination result by the information acquisition determination unit 332d. Become. At this time, for example, the switching determination unit 332 selects the wireless communication media 10 for which predetermined information has been acquired, and transmits information to the wireless communication media switching unit 34 so as to switch or maintain the communication connection. As a result, the navigation device 3 can select the wireless communication medium 10 for which the predetermined information has been acquired, and can download smoothly.

  Here, when the information acquisition determination unit 332d determines that the download is not completed regardless of whether the communication connection is switched or not, the switching determination unit 332 includes a first information completion time calculation unit (first information completion time calculation unit). It is determined whether or not to switch the communication connection based on information from 332e and the second information completion time calculation unit (second information completion time calculation unit) 332f.

  First, the first information completion time calculation unit 332e calculates the time until the predetermined information is acquired when the communication connection is switched to the new wireless communication medium 10. That is, the first information completion time calculation unit 332e acquires information on the remaining information capacity to be acquired from the remaining capacity calculation unit 332c. And the 1st information completion time calculation part 332e acquires the throughput information of the Bluetooth network 6 when the vehicle is located at the boundary point 102 in FIG. Next, the first information completion time calculation unit 332e obtains the time required to complete the acquisition from the throughput and the remaining information capacity to be acquired.

  In addition, the second information completion time calculation unit 332f calculates a time until the predetermined information is completely acquired when the communication connection to the new wireless communication medium 10 is not switched. That is, the second information completion time calculation unit 332f acquires information on the remaining information capacity that should be acquired from the remaining capacity calculation unit 332c, similarly to the first information completion time calculation unit 332e. Then, when the vehicle is located at the boundary point 102 in FIG. 2, the second information completion time calculation unit 332f acquires information on the throughput of the mobile phone network 4, and from this throughput and the remaining information capacity to be acquired, Find the time required to complete the acquisition.

  Accordingly, the switching determination unit 332 performs wireless communication that is currently connected to the wireless communication based on the time until the completion of acquisition calculated by the first information completion time calculation unit 332e and the second information completion time calculation unit 332f. It is determined whether the communication connection is switched from the medium 10 to the new wireless communication medium 10. At this time, the switching determination unit 332 sends information to the wireless communication media switching unit 34 so as to switch or maintain the communication connection by selecting the one with a shorter time until acquisition is completed so that as much information amount as possible can be acquired. Send.

  Next, a wireless communication media switching method according to this embodiment will be described. FIG. 4 is a flowchart showing the wireless communication media switching method according to the present embodiment. As shown in FIG. 4, the navigation device 3 acquires predetermined information from the information center 2 via the plurality of wireless communication media 10 while switching communication connections with the plurality of wireless communication media 10.

  That is, as shown in the figure, when download is instructed by a driver's instruction or the like, the control unit 33 of the navigation device 3 starts downloading predetermined information from the information center 2 through the communication control unit 32 ( S400). At this time, the communication control unit 32 obtains and stores the total information capacity of the predetermined information to be acquired from the information center 2 or from the past history.

  Next, the effective area acquisition unit 331 of the control unit 33 acquires the communication effective area information of the wireless communication media 10 from the information center 2 and also acquires the throughput information of each wireless communication medium 10 (S401). Specifically, the effective area acquisition unit 331 acquires communication effective area and throughput information regarding the wireless communication medium 10 covering a part or all of the vehicle guidance route. That is, in the example of FIG. 2, the effective area acquisition unit 331 acquires information on the communication effective areas of the mobile phone network 4, the wireless LAN network 5, and the Bluetooth network 6 together with the throughput. At this time, the effective area acquisition unit 331 also acquires information on the time required for switching the wireless communication media 10.

  Next, the control unit 33 obtains route information from which the vehicle is currently guided from the vehicle guidance unit 35 (S402). Then, the boundary line calculation unit 37 obtains the boundary line of the effective communication area acquired in step S401 (S403). At this time, the boundary line calculation unit 37 obtains a boundary point between the route where the vehicle is currently guided and the effective communication area of the wireless communication medium 10, and stores this boundary point as a switching candidate point of the wireless communication medium 10. Keep it. That is, the boundary line calculation unit 37 obtains the boundary points 102 to 107 shown in FIG. 2 and stores them as switching candidate points. In addition, when the boundary line calculation unit 37 stores the switching candidate points, the boundary line calculation unit 37 also stores information on the latitude and longitude.

  Thereafter, the control unit 33 acquires the current position information of the vehicle from the vehicle guiding unit 35 (S404). Then, the control unit 33 determines whether or not predetermined information is currently being downloaded (S405). At this time, the control unit 33 makes an inquiry to the communication control unit 32 as to whether or not downloading is in progress. If it is determined that the download is not in progress (S405: NO), the process ends because the predetermined information has been acquired.

  On the other hand, when it is determined that the download is in progress (S405: YES), the control unit 33 determines whether or not the vehicle guidance route information has been changed (S406). At this time, the control unit 33 inquires of the vehicle guidance unit 35 whether there is a change in route information. If it is determined that there has been a change (S406: YES), the process returns to step S402, and the guidance route information is acquired again.

  On the other hand, when it is determined that there is no change (S406: NO), the switching determination unit 332 compares the current position acquired in step S404 with the switching candidate point stored in step S403, and the own vehicle is a switching candidate. It is determined whether or not the point has been reached (S407).

  At this time, the switching determination unit 332 determines whether or not the host vehicle has reached the switching candidate point by the following method. First, the switching determination unit 332 sets a first change candidate point and a second change candidate point. The first change candidate point is the switching candidate point of the wireless communication media 10 that is closest to the current point (the difference between latitude and longitude is small), and the second change candidate point is next to the first change candidate point. This is a candidate point for switching the wireless communication media 10. For example, when the vehicle is at the current position 100 in FIG. 2, the first change candidate point is the boundary point 102, and the second change candidate point is the boundary point 103.

  Thereafter, the switching determination unit 332 determines whether or not the host vehicle is located between the first change candidate point and the second change candidate point. Then, when determining that the host vehicle is located between the first change candidate point and the second change candidate point, the switch determination unit 332 determines that the host vehicle has reached the switch candidate point (S407: YES), the process proceeds to step S408 in FIG.

  On the other hand, when determining that the vehicle is not located between the first change candidate point and the second change candidate point (S407: NO), the switch determination unit 332 determines that the host vehicle has not reached the switch candidate point. (S407: NO), the process returns to step S404.

  The switching determination unit 332 may simply determine whether or not the current position matches the switching candidate point without setting the first change candidate point and the second change candidate point.

  Next, in step S408, the switching determination unit 332 determines whether or not the predetermined information has been downloaded by the new wireless communication medium 10 to be switched, and determines whether the predetermined information is transmitted by the wireless communication medium 10 that is currently performing wireless communication. It is determined whether or not the download is completed (S408).

  This process will be described in detail. First, in step S408, the first information capacity calculation unit 332a calculates the information capacity of predetermined information that can be acquired when the communication connection is switched to the new wireless communication medium 10. Specifically, the first information capacity calculation unit 332a obtains the “distance to the second change candidate point” by the relational expression “second change candidate point” − “current position”.

  Thereafter, the first information capacity calculation unit 332a calculates “distance to the second change candidate point” ÷ “vehicle speed” to “arrival time to the second change candidate point”. At this time, the first information capacity calculation unit 332a may obtain the “arrival time to the second change candidate point” in consideration of the traffic jam information.

  Next, the first information capacity calculation unit 332a determines from “arrival time to the second change candidate point” − “time to switch communication connection to the new wireless communication medium 10” to “communication time to the second change candidate point”. Ask for. Then, the first information capacity calculation unit 332a calculates “the information capacity that can be acquired by the new wireless communication medium 10” from “the communication possible time to the second change candidate point” × “the throughput of the new wireless communication medium 10”. Is calculated.

  Further, the second information capacity calculation unit 332b inputs “arrival time to the second change candidate point” from the first information capacity calculation unit 332a, and “arrival time to the second change candidate point” × “current wireless The “information capacity that can be acquired by the current wireless communication medium 10” is calculated by the relational expression “throughput of the communication medium 10”.

  In addition, the remaining capacity calculation unit 332c calculates the remaining information capacity to be acquired from the currently downloaded information capacity and the total information capacity of the predetermined information acquired in step S400. Then, the information acquisition determination unit 332d uses the new wireless communication medium 10 and the wireless communication medium 10 currently communicating based on the calculation results by the first and second information capacity calculation units 332a and 332b and the remaining capacity calculation unit 332c. It is determined whether or not the remaining amount of predetermined information can be acquired.

  At this time, if the “information capacity that can be acquired with the new wireless communication medium 10” is greater than or equal to the remaining information capacity to be acquired, the information acquisition determination unit 332d transmits predetermined information using the new wireless communication medium 10. Judge that the download is complete. In addition, when the “information capacity that can be acquired with the current wireless communication medium 10” is greater than or equal to the remaining information capacity to be acquired, the information acquisition determination unit 332d performs predetermined information using the wireless communication medium 10 that is currently communicating. Is determined to be downloaded. In this way, the switching determination unit 332 performs the process of step S408.

  Next, in step S408, when the information acquisition determination unit 332d determines that the predetermined information has not been downloaded by any of the wireless communication media 10, the process proceeds to step S409. Then, the switching determination unit 332 determines whether or not the “information capacity that can be acquired by the current wireless communication medium 10” is larger than the “information capacity that can be acquired by the new wireless communication medium 10” (S409).

  Here, when it is determined that the “information capacity that can be acquired with the current wireless communication medium 10” is larger than the “information capacity that can be acquired with the new wireless communication medium 10” (S409: YES), the switching determination unit 332 If it is determined that the communication connection is not switched to the new wireless communication medium 10, the process returns to step S404.

  At this time, the switching determination unit 332 cancels the setting of the first change candidate point and deletes the data at that point. Further, when it is not necessary to execute the communication connection switching determination at the second change candidate point, the switching determination unit 332 cancels the setting of the second change candidate point and deletes the data. Specifically, when the switching determination unit 332 determines not to switch the communication connection to the Bluetooth network 6 at the boundary point 102 illustrated in FIG. 2, the communication connection with the mobile phone network 4 is maintained. For this reason, it is not necessary to determine whether or not to switch the communication connection to the mobile phone network 4 at the boundary point 103, and the switching determination unit 332 cancels the setting of the boundary point 103 as the second change candidate point and stores the data. It will be deleted. Thereafter, the process returns to step S404.

  In addition, when there is a possibility of switching the communication connection to the new wireless communication medium 10 at the second change candidate point, the switching determination unit 332 sets the setting of the second change candidate point as the first change candidate point. . That is, in FIG. 2, the boundary point 103 is a place where the Bluetooth network 6 is switched to the mobile phone network 4, but if the boundary point 103 is a place where the Bluetooth network 6 is switched to the wireless LAN network 5, Even if the communication connection with the telephone network 4 is maintained, it is necessary to make a switching determination at the boundary point 103. Therefore, the switching determination unit 332 sets the second change candidate point as the first change candidate point. Thereafter, the process returns to step S404.

  On the other hand, if it is determined that the “information capacity that can be acquired with the current wireless communication medium 10” is not greater than the “information capacity that can be acquired with the new wireless communication medium 10” (S409: NO), the switching determination unit 332 It is determined that the communication connection is switched to the new wireless communication medium 10. Then, the switching determination unit 332 designates the wireless communication media 10 to be switched to the wireless communication media switching unit 34 and issues a switching command. Next, the wireless communication media switching unit 34 issues a control command to the communication control unit 32, and the communication control unit 32 establishes a communication connection with the new wireless communication medium 10 (S412). At this time, the switching determination unit 332 cancels the setting of the first change candidate point and deletes the data at that point. Further, the switching determination unit 332 sets the second change candidate point as a new first switch candidate point, and sets the next closest switch candidate point as a new second change candidate point. Then, the process returns to step S404.

  As described above, when the predetermined information is not completely downloaded by any of the wireless communication media 10, the present apparatus 3 determines whether or not to switch the communication connection so as to obtain as much information as possible. It will be.

  In step S408, when the information acquisition determination unit 332d determines that the predetermined information has been downloaded by any one of the wireless communication media 10, the process proceeds to step S410. In step S410, the switching determination unit 332 determines whether or not the current wireless communication medium 10 has been downloaded (S410).

  Here, when it is determined that the download is completed with the current wireless communication medium 10 (S410: YES), the switching determination unit 332 determines that the communication connection is not switched, and executes the deletion of the first change candidate point and the like. Then, the process returns to step S404. On the other hand, when it is determined that the download is not completed with the current wireless communication medium 10 (S410: NO), the switching determination unit 332 determines to switch the communication connection to the new wireless communication medium 10. Then, the switching determination unit 332 issues a command to the communication control unit 32 through the wireless communication media switching unit 34, and the communication control unit 32 establishes a communication connection with the new wireless communication media 10 (S412). At this time, the switching determination unit 332 sets a new first change candidate point and a second change candidate point, and the process returns to step S404.

  When the distance from the current location to the second change candidate point is short (when the effective communication area is narrow), “the arrival time to the second change candidate point” − “switch the communication connection to the new wireless communication medium 10” The “communication time to the second change candidate point” obtained from “time” may be a negative value. That is, when the communication connection is switched to the new wireless communication medium 10, the number of times of switching the wireless communication medium 10 may be inappropriately increased. However, when the “communication available time to the second change candidate point” is a negative value and the process proceeds to step S410, the information capacity that can be acquired when the communication connection is switched is reduced. Therefore, the process proceeds to step S404 without determining that the communication connection is switched in step S410. That is, an inappropriate increase in the number of times of switching of the wireless communication media 10 is prevented.

  Furthermore, in step S408, when the information acquisition determination unit 332d determines that the predetermined information has been downloaded by both wireless communication media 10, the process proceeds to step S411. In step S411, the switching determination unit 332 determines whether or not the current wireless communication medium 10 finishes downloading earlier than the new wireless communication medium 10 (S411).

  Here, when it is determined that the current wireless communication medium 10 finishes downloading earlier (S411: YES), the switching determination unit 332 determines that the communication connection is not switched, and deletes the first change candidate point or the like. Once executed, the process returns to step S404. On the other hand, when it is determined that the current wireless communication medium 10 has not finished downloading earlier (S411: NO), the switching determination unit 332 determines to switch the communication connection to the new wireless communication medium 10. Then, the communication control unit 32 establishes a communication connection with the new wireless communication medium 10 (S412), and the switching determination unit 332 sets a new first change candidate point and a second change candidate point. Then, the process returns to step S404.

  Here, the determination in step S411 will be described in detail. In step S <b> 411, the first information completion time calculation unit 332 e calculates the time until the predetermined information is acquired when the communication connection is switched to the new wireless communication medium 10. That is, first, the first information completion time calculation unit 332e acquires information on the remaining information capacity to be acquired from the remaining capacity calculation unit 332c. Next, the first information completion time calculation unit 332e has a relationship of “remaining information capacity to be acquired” ÷ “throughput of the new wireless communication medium 10” + “time for switching communication connection to the new wireless communication medium 10”. From the equation, “time until completion of acquisition by new wireless communication medium 10” is calculated.

  In addition, the second information completion time calculation unit 332f calculates the time until the acquisition of acquisition information is completed when the communication connection is not switched to the new wireless communication medium 10. That is, first, the second information completion time calculation unit 332f acquires information on the remaining information capacity to be acquired from the remaining capacity calculation unit 332c, and obtains “remaining information capacity to be acquired” ÷ “current wireless communication. The “time until completion of acquisition by the current wireless communication medium 10” is calculated from the relational expression “throughput of the medium 10”.

  As a result, the switching determination unit 332 uses the wireless communication media currently connected for communication based on the time until the completion of acquisition calculated by the first information completion time calculation unit 332e and the second information completion time calculation unit 332f. 10 determines whether or not the predetermined information has been acquired earlier than the new wireless communication medium 10.

  And this apparatus 3 will perform said switching method repeatedly until it arrives at the destination, and will perform smooth download.

  Thus, according to the navigation device 3 and the wireless communication media switching method according to the present embodiment, the communication effective area information of the plurality of wireless communication media 10 is obtained from the information center 2 to obtain the boundary, Based on the boundary and the current vehicle position, it is determined whether or not to switch the communication connection from the wireless communication medium 10 connected by wireless communication to the new wireless communication medium 10. For this reason, it is possible to perform communication connection switching control when the vehicle reaches the boundary of the communication effective area and perform communication connection switching control, and depending on the switching determination result, the communication speed may be high. Even if the vehicle enters the communication effective area of the wireless communication medium 10, it is possible not to switch the communication connection. As a result, for example, it is possible to prevent a situation where the number of switching increases and download communication efficiency decreases due to connection to the wireless communication medium 10 having a high communication speed but a narrow communication range. Therefore, information can be downloaded smoothly.

  In addition, the information capacity of the predetermined information that can be acquired when switching to the new wireless communication medium 10, the information capacity of the predetermined information that can be acquired without switching, and the remaining information capacity to be acquired are calculated. Therefore, it is determined whether or not the remaining amount of the predetermined information can be acquired by the new wireless communication medium 10 or the wireless communication medium 10 currently in communication. Then, according to the determination result, it is determined whether or not the communication connection is switched from the wireless communication medium 10 connected by wireless communication to the new wireless communication medium 10. For this reason, it is possible to prevent the communication connection from being switched to the wireless communication medium 10 in which the remaining amount of predetermined information cannot be acquired, and a smoother download can be performed.

  Also, the time until the predetermined information is completely acquired when switching to the new wireless communication medium 10 and the time until the predetermined information is completely acquired when not switching are calculated. Then, when it is determined that the remaining amount of the predetermined information can be acquired without switching even when switching to the new wireless communication medium 10, based on the time until the completion of acquisition calculated with and without switching, It is determined whether or not to switch the communication connection from the wireless communication medium 10 connected to the wireless communication to a new wireless communication medium 10. For this reason, the wireless communication medium 10 that completes the download at an early stage can be selected from the time until the acquisition is completed, and a smoother download can be performed.

  Next, a second embodiment of the present invention will be described. The information distribution system 1 including the navigation device 3 according to the second embodiment is the same as that of the first embodiment, but the configuration and the wireless communication when the navigation device 3 switches the communication connection to the new wireless communication medium 10. Some media switching methods are different.

  The processing contents of the navigation device 3 according to the second embodiment will be described with reference to FIG. As shown in FIG. 4, the navigation device 3 according to the first embodiment switches the communication connection to the new wireless communication medium 10 in step S412. However, in the navigation device 3 according to the second embodiment, in step S412, the driver is notified whether or not the communication connection is to be switched.

  For example, the navigation device 3 according to the second embodiment informs the driver whether or not to switch the communication connection by display on the display unit or voice notification, and the communication is performed when the driver instructs to switch the communication connection. Switch the connection destination. And the navigation apparatus 3 will return a process to step S404. On the other hand, when there is no instruction to switch from the driver, the navigation device 3 returns the process to step S404 without switching the communication connection destination.

  In this way, according to the navigation device 3 and the wireless communication media switching method according to the second embodiment, information can be downloaded smoothly as in the first embodiment. In addition, a smoother download can be performed.

  Further, according to the second embodiment, the communication connection destination desired by the driver can be selected, and convenience can be improved. Furthermore, in addition to the information on whether or not to switch the wireless communication medium 10 to the driver, information such as whether the switching can end the download earlier and information on the priority are also presented. Also good. Thereby, it is difficult to impair the download efficiency and the convenience can be improved.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention.

  For example, the navigation device 3 includes an effective area acquisition unit 331 and causes the wireless communication media information storage unit 36 to store communication effective area information of a plurality of wireless communication media 10 acquired by the effective area acquisition unit 331. It was. However, the present invention is not limited to this, and information on communication effective area information for a plurality of wireless communication media 10 may be stored in the wireless communication media information storage unit 36 in advance. In this case, the boundary calculation unit 37 calculates the boundary of the communication effective area of each wireless communication medium 10 based on the communication effective area information of the plurality of wireless communication media 10 stored in advance. As described above, even when the information of the communication effective area information is stored in the wireless communication media information storage unit 36 in advance, the information can be downloaded smoothly as described above. In addition, the configuration for acquiring the communication effective area information (the effective area acquisition unit 331 in FIG. 3) is not necessary, and the configuration can be simplified. In the above case, the wireless communication media information storage unit 36 may store information at the time of manufacturing, or may store information based on past history.

  In addition, the information distribution system 1 is not limited to the configuration in which the boundary line calculation unit 37 and the switching determination unit 332 are provided in the navigation device 3, but is provided in the information center 2 so that the information center 2 itself communicates with the wireless communication medium 10. It may be configured to determine whether to switch the connection.

  In this case, the information center 2 includes a position acquisition unit that acquires information on the current vehicle position from the vehicle. In addition, the information center 2 is newly provided with a center-side storage unit that stores information on the effective communication area for the plurality of wireless communication media 10 for wirelessly transmitting predetermined information to the vehicle. Then, the boundary line calculation unit 37 calculates the boundary line of the communication effective area of each wireless communication medium 10 from the communication effective area information of the plurality of wireless communication media 10 stored by the center-side storage unit. In addition, the switching determination unit 332 establishes wireless communication connection of the vehicle based on the boundary line of the communication effective area calculated by the boundary line calculation unit 37 in the center 2 and the current position of the vehicle transmitted from the vehicle side. It is determined whether or not to switch from the wireless communication medium 10 being switched to a new wireless communication medium 10.

  Thus, even when the information center 2 determines whether or not to switch the communication connection of the wireless communication medium 10, the information center 2 can connect the communication connection of the vehicle via any one of the plurality of wireless communication media 10. By controlling the destination, the navigation device 3 can smoothly download the information as described above. Moreover, the navigation apparatus 3 can simplify the configuration of the information distribution system 1 as a whole without individually including the boundary line calculation unit 37 and the switching determination unit 332.

1 is a configuration diagram of an information distribution system including a navigation device and an information center according to an embodiment of the present invention. It is explanatory drawing which shows a mode that a navigation apparatus switches the communication connection of a wireless communication medium. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the navigation apparatus which concerns on embodiment of this invention, (a) has shown the whole structure of the navigation apparatus, (b) has shown the partial detailed structure of the navigation apparatus. It is a flowchart which shows the wireless communication media switching method which concerns on this embodiment.

Explanation of symbols

2 ... Information center 3 ... Navigation device 10 ... Wireless communication medium 35 ... Vehicle guidance section (current position detection means)
36 ... Wireless communication media information storage unit (effective area storage means)
37 ... Boundary line calculation unit (boundary line calculation means)
331 ... Effective area acquisition unit (effective area acquisition means)
332... Switching determination unit (switching determination means)
332a ... 1st information capacity calculation part (1st information capacity calculation means)
332b ... second information capacity calculator (second information capacity calculator)
332c ... Remaining capacity calculation unit (remaining capacity calculation means)
332d ... Information acquisition determination unit (information acquisition determination means)
332e ... first information completion time calculation unit (first information completion time calculation means)
332f ... second information completion time calculation unit (second information completion time calculation means)

Claims (6)

In a navigation device that acquires predetermined information from an information center that is a source of information via wireless communication media,
Current position detecting means for detecting the current position of the vehicle;
Effective area acquisition means for acquiring information of a communication effective area for a plurality of wireless communication media from the information center;
Boundary line calculation means for calculating the boundary line of the communication effective area of each wireless communication medium from the communication effective area information of the plurality of wireless communication media acquired by the effective area acquisition means;
Based on the boundary line of the effective communication area calculated by the boundary line calculating means and the current position detected by the current position detecting means, the wireless communication medium connected by wireless communication is changed to a new wireless communication medium. Switching determination means for determining whether to switch communication connections;
A navigation device comprising: The switching determination means includes
First information capacity calculating means for calculating an information capacity of predetermined information that can be acquired when switching to a new wireless communication medium;
A second information capacity calculating means for calculating an information capacity of predetermined information that can be acquired when switching to a new wireless communication medium;
Of the predetermined information, a remaining capacity calculating means for calculating the remaining information capacity to be acquired;
Based on the calculation results of the first and second information capacity calculating means and the remaining capacity calculating means, the remaining amount of predetermined information can be acquired when switching to a new wireless communication medium and when not switching. Information acquisition determination means for determining whether or not,
The navigation apparatus according to claim 1, wherein it is determined whether or not to switch from a wireless communication medium connected by wireless communication to a new wireless communication medium according to a determination result by the information acquisition determination unit. The switching determination means includes
First information completion time calculating means for calculating a time until acquisition of predetermined information when switching to a new wireless communication medium;
Second information completion time calculating means for calculating a time until acquisition of predetermined information when not switching to a new wireless communication medium,
When the information acquisition determination unit determines that the remaining amount of predetermined information can be acquired without switching to a new wireless communication medium, the acquisition completion calculated by the first and second information completion time acquisition units The navigation apparatus according to claim 2, wherein it is determined whether or not to switch from a wireless communication medium connected by wireless communication to a new wireless communication medium based on the time until the time. In a navigation device that acquires predetermined information from an information center that is a source of information via wireless communication media,
Current position detecting means for detecting the current position of the vehicle;
Effective area storage means for preliminarily storing communication effective area information for the plurality of wireless communication media;
Boundary line calculation means for calculating the boundary line of the communication effective area of each wireless communication medium from the communication effective area information of the plurality of wireless communication media stored by the effective area storage means;
Based on the boundary line of the effective communication area calculated by the boundary line calculating means and the current position detected by the current position detecting means, the wireless communication medium connected by wireless communication is changed to a new wireless communication medium. Switching determination means for determining whether to switch communication connections;
A navigation device comprising: In an information center that transmits predetermined information to a vehicle via wireless communication media,
Position acquisition means for acquiring information on the current vehicle position from the vehicle;
For a plurality of wireless communication media for wirelessly transmitting predetermined information to the vehicle, a center-side storage unit that stores information of a communication effective area;
Boundary line calculation means for calculating a boundary line of the communication effective area of each wireless communication medium from the communication effective area information of the plurality of wireless communication media stored by the center side storage means;
Based on the boundary line of the effective communication area calculated by the boundary line calculation unit and the current position of the vehicle acquired by the position acquisition unit, a new communication is established from the wireless communication medium to which the vehicle is connected by wireless communication Switching determination means for determining whether to switch communication connection to wireless communication media;
An information center comprising: In the wireless communication media switching method of acquiring while switching the communication connection with a plurality of wireless communication media in acquiring predetermined information from the information center that is the source of information via the plurality of wireless communication media,
An effective area acquisition step of acquiring information of a communication effective area for a plurality of wireless communication media from the information center;
From the communication effective area information of a plurality of wireless communication media acquired in the effective area acquisition step, a boundary line calculating step of calculating a boundary line of the communication effective area of each wireless communication medium;
Based on the boundary line of the effective communication area calculated in the boundary line calculating step and the detected current position of the vehicle, communication connection is established from the wireless communication medium connected to the wireless communication to a new wireless communication medium. A switching determination step for determining whether to switch;
A wireless communication media switching method comprising:

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