Handover method, handover system, and handover apparatus

Abstract

To provide a method, a device and a system for achieving a handover method capable of minimizing communication interruption and maintaining a communicable state.SOLUTION: Acquiring a future planned moving route of a mobile body, extracting area information of a candidate base station that is a base station to which a communication device is connectable on the planned moving route from a communication information storage unit, and predicting a moving time required for the mobile body to move on the planned moving route included in a handover area in which a communication area of a connection source base station that is one candidate base station and a communication area of another candidate base station overlap with each other and handover from the connection source base station to the other candidate base station is possible among communication areas indicated by the extracted area information; A connection destination base station to which the communication device is connected is selected from the other candidate base stations on the basis of the moving time, and when the mobile body moves to a handover area, the base station to which the communication device is connected is handed over from the connection source base station to the connection destination base station.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a handover method for handing over a base station to which a communication device mounted on a mobile object such as a car is connected, a handover system for executing the handover method, and a handover device. [Background technology]

[0002] As wireless communication becomes more widespread, opportunities to communicate using wireless communication are increasing in various places. In particular, for mobile objects such as automobiles, technologies that use wireless communication functions to provide driving assistance and autonomous driving control are attracting attention. As a result, vehicles are increasingly equipped with communication functions, and the so-called "connected vehicles" trend is progressing.

[0003] When a communication terminal moves, such as in a vehicle, it is necessary to switch the base station device that communicates with it as it moves, a process known as handover.If there are multiple base stations that can be connected to at the destination, it is necessary to select an appropriate base station device from among the available base stations.

[0004] For example, Patent Document 1 describes that a wireless terminal device sets priorities for target APs that are candidates for handover destinations based on connection history information of the wireless base station device to which it was wirelessly connected before handing over to the current AP, and when performing a handover, it attempts to establish a wireless connection with the target AP according to the set priorities, and hands over to the target AP with which it was able to establish a wireless connection first. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-49922 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the present inventors have found the following problems as a result of detailed investigations. Handovers are usually performed near the boundaries of the communication areas of wireless base stations. This is done to prevent communication interruptions by performing handovers in areas where multiple wireless base stations are connectable. However, in wireless communications using terminal devices mounted on fast-moving mobile devices, the terminal devices only stay within the communication areas of wireless base stations for a short period of time. In particular, when using a communication method such as Wi-Fi, where the communication areas of each wireless base station are relatively narrow, the mobile device may quickly pass through areas where multiple wireless base stations are connectable, and there is a risk of wireless communication being interrupted due to insufficient time for switching between wireless base stations.

[0007] Therefore, the present invention aims to prevent wireless communication interruptions by having a communication device mounted on a mobile body select a base station device that can ensure sufficient time for switching wireless base stations as the base station to connect to. [Means for solving the problem]

[0008] The handover method disclosed herein is a handover method for handing over a base station to which a communication device mounted on a mobile body is connected, and includes: acquiring a future planned movement route of the mobile body (S101, S301); extracting area information of candidate base stations that are base stations that can be connected to the communication device on the planned movement route from a communication information storage unit that stores area information indicating communication areas in which the base stations can communicate (S102, S302); and extracting a communication area indicated by the extracted area information from a communication information storage unit that extracts a communication area of ​​one of the candidate base stations and a communication area of ​​another candidate base station. The method predicts the travel time required for the mobile body to travel the planned travel route included in a handover area where a communication area overlaps with the communication area and where handover from the source base station to the other candidate base station is possible (S103, S303), and based on the travel time, selects a destination base station to which the communication device will be handed over from the source base station from the other candidate base stations (S153), and when the mobile body moves into the handover area, hands over the base station to which the communication device is connected from the source base station to the destination base station (S155).

[0009] It should be noted that the claims and the numbers in parentheses attached to the constituent elements of the invention described in this section indicate the correspondence between the present invention and the embodiments described below, and are not intended to limit the present invention. [Effects of the Invention]

[0010] With the above-described configuration, the handover method and the like of the present disclosure can prevent wireless communication from being interrupted when a handover is performed from a source base station to a destination base station. [Brief explanation of the drawings]

[0011] [Figure 1] An overall diagram showing the devices used in the handover system of each embodiment and their interrelationships. [Figure 2] FIG. 1 is a block diagram showing an example of the configuration of a server device and an in-vehicle device according to a first embodiment. [Figure 3] FIG. 1 is a diagram illustrating a communication information storage unit according to the first embodiment. [Figure 4]FIG. 1 is a diagram illustrating a communication area and a planned travel route according to the first embodiment. [Figure 5] FIG. 10 is a diagram illustrating a travel time prediction process in a travel time prediction unit according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating a travel time prediction process in a travel time prediction unit according to the first embodiment. [Figure 7] FIG. 1 is a diagram for explaining handover information according to the first embodiment. [Figure 8] FIG. 1 is a diagram for explaining a base station selection process according to the first embodiment. [Figure 9] 1 is a flowchart illustrating the operation of the handover system according to the first embodiment. [Figure 10] 1 is a flowchart illustrating the operation of the handover system according to the first embodiment. [Figure 11] FIG. 1 is a diagram for explaining a base station selection process according to the first embodiment. [Figure 12] FIG. 1 is a diagram for explaining a base station selection process according to the first embodiment. [Figure 13] FIG. 10 is a block diagram showing an example of the configuration of a server device and an in-vehicle device according to a second [Figure 14] 10 is a flowchart illustrating the operation of the handover system according to the second embodiment. [Figure 15] FIG. 10 is a block diagram showing an example of the configuration of an in-vehicle device according to a third embodiment. [Figure 16] 10 is a flowchart illustrating the operation of a handover system according to a third embodiment. [Figure 17] FIG. 10 is a diagram illustrating a base station selection process according to Modification 1. [Figure 18] FIG. 10 is a diagram illustrating a base station selection process according to Modification 1. [Figure 19] Flowchart for explaining the operation of the base station selection unit according to Modification 1 [Figure 20] A block diagram showing a configuration example of an in-vehicle device according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] The present invention refers to the inventions described in the claims or in the Summary of the Invention section, and is not limited to the following embodiments. Furthermore, at least the words in quotation marks refer to the words described in the claims or in the Summary of the Invention section, and are not limited to the following embodiments.

[0014] The configurations and methods recited in the dependent claims are optional configurations and methods in the inventions recited in the independent claims. The configurations and methods of the embodiments corresponding to the configurations and methods recited in the dependent claims, as well as the configurations and methods recited only in the embodiments without being recited in the claims, are optional configurations and methods in the present invention. The configurations and methods recited in the embodiments when the recitation of the claims is broader than the recitation of the embodiments are also optional configurations and methods in the present invention, in the sense that they are examples of the configurations and methods of the present invention. In either case, by being recited in the independent claims, they become essential configurations and methods of the present invention.

[0015] The effects described in the embodiments are effects obtained when the configurations of the embodiments are provided as examples of the present invention, and are not necessarily effects that the present invention has.

[0016] When there are multiple embodiments, the configurations disclosed in each embodiment are not limited to each embodiment, but can be combined across the embodiments. For example, a configuration disclosed in one embodiment may be combined with another embodiment. Also, configurations disclosed in multiple embodiments may be collected and combined.

[0017] The problem described in the section on the problem to be solved by the invention is not a publicly known problem, but was discovered independently by the inventor, and this fact, together with the configuration and method of the present invention, affirms the inventive step of the invention.

[0018] 1. Interrelationships between related devices in each embodiment First, with reference to FIG. 1, an overall configuration showing the devices used in the handover system S of each embodiment and their interrelationships will be described.

[0019] Fig. 1(a) shows that the handover system S is a system having a server device 1 provided outside a vehicle, which is a "moving body," and an in-vehicle device 2 "mounted" on the vehicle. Fig. 1(b) shows that the handover system S is a system consisting of an in-vehicle device 2 "mounted" on a vehicle, which is a "moving body." In addition to the in-vehicle device 2, the vehicle is equipped with a communication device 3.

[0020] Here, "mobile body" refers to an object that can move at any speed. It also naturally includes cases where the moving body is stationary. Examples include, but are not limited to, automobiles, motorcycles, bicycles, pedestrians, ships, aircraft, and objects mounted on these vehicles. "Mounted" includes not only cases where the device is directly fixed to the mobile body, but also cases where the device is not fixed to the mobile body but moves with the mobile body. For example, cases where the device is carried by a person riding on the mobile body, or cases where the device is mounted on cargo placed on the mobile body, are included.

[0021] The handover system S described in the first and second embodiments corresponds to Fig. 1(a), and the handover system S described in the third embodiment corresponds to Fig. 1(b). In the first embodiment, the server device 1 corresponds to the handover information providing device 100, and the in-vehicle device 2 corresponds to the handover device 150. In the second embodiment, the server device 1 corresponds to the handover instruction device 200, and the in-vehicle device 2 corresponds to the handover device 250. In the third embodiment, the in-vehicle device 2 corresponds to the handover device 350.

[0022] Although the in-vehicle device 2 and the communication device 3 are shown as separate devices in FIG. 1, the communication device 3 may be provided with the functions of the in-vehicle device 2 in each embodiment described below.

[0023] The communication device 3 mounted on the vehicle performs wireless communication via a base station. The communication device 3 performs communication using a communication network that uses a wireless communication method such as IEEE802.11 (Wi-Fi (registered trademark)), IEEE802.16 (WiMAX (registered trademark)), W-CDMA (Wideband Code Division Multiple Access), HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution), LTE-A (Long Term Evolution Advanced), 4G, or 5G.

[0024] The communication device 3 is connected to the server device 1 via the above-mentioned communication network. The communication device 3 may further be connected to another server device (not shown) that controls the automatic driving of the vehicle or collects logs generated by the vehicle. In Fig. 1(a), a base station connecting the server device 1 and the communication device 3 is omitted.

[0025] In the following embodiment, a configuration in which the communication device 3 communicates using the Wi-Fi wireless communication system will be described as an example. When communicating using the Wi-Fi wireless communication system, the communication device 3 transmits a connection request to a base station. The communication device 3 may transmit authentication information (e.g., a password) required for connection to the base station along with the connection request. Then, once the communication device 3 is authenticated by the base station, it becomes possible for the communication device 3 to communicate via the base station.

[0026] The communication device 3 may have multiple communication modules and may be a device capable of communicating using multiple communication methods. For example, the communication device 3 may have two Wi-Fi communication modules, and each of the two communication modules may communicate using Wi-Fi. Alternatively, the communication device 3 may have a Wi-Fi communication module and a 4G communication module, and each of the two communication modules may communicate using a different communication method.

[0027] 2. Embodiment 1 (1) Configuration of Server Device 1 (Handover Information Providing Device 100) The configuration of the server device 1 of this embodiment will be described with reference to Fig. 2. In this embodiment, the server device 1 has a function as a handover information providing device 100.

[0028] The handover information providing device 100, which is the server device 1, includes a route acquisition unit 101, a communication status acquisition unit 102, a communication information storage unit 103, a control unit 104, and a handover information transmission unit 107. The control unit 104 realizes a communication information extraction unit 105 and a travel time prediction unit 106.

[0029] The route acquisition unit 101 acquires route information indicating a planned future travel route of the vehicle. For example, the route acquisition unit 101 receives the route information indicating a planned travel route derived by a navigation device or the like provided in the vehicle from the vehicle via wireless communication. Alternatively, the route acquisition unit 101 may acquire the route information from a route derivation unit (not shown) provided outside the vehicle that acquires the vehicle's current position information and destination information from the vehicle and derives a planned travel route.

[0030] While the vehicle is moving, the route may be changed due to traffic congestion or the passenger's request. In such a case, the route acquisition unit 101 may timely acquire route information indicating the planned route after the change. The planned route may also be a part of the route from the current position of the vehicle to the destination.

[0031] The communication status acquisition unit 102 acquires communication status information indicating the communication status of the base station. For example, the communication status acquisition unit 102 acquires, from a communication device 3 that has attempted to connect to the base station, information such as the reception strength of a wireless signal from the base station and whether or not connection to the base station is possible, as the communication status information. Alternatively, the communication status acquisition unit 102 may acquire, directly from the base station, information such as whether or not the base station is operating and whether or not the number of communication devices that can connect to the base station has been reached, as the communication status information.

[0032] The communication status acquisition unit 102 may further acquire handover record information indicating the time actually required for the communication device 3 to perform handover from one base station to another base station (corresponding to "handover time").

[0033] The communication information storage unit 103 is a storage unit that stores base station information indicating a base station and area information indicating a communication area in which communication with the base station is possible. The base station information may include, for example, location information of the base station, the SSID (Service Set Identifier) ​​of the base station, a password required for connection to the base station, etc. The communication information storage unit 103 further stores the communication status information and handover record information acquired by the communication status acquisition unit 102.

[0034] FIG. 3 shows an example of information stored in the communication information storage unit 103. In the example of FIG. 3, base station information including a base station ID and location information of the base station is stored. Furthermore, the area information in FIG. 3 is simply illustrated as A1 to A9, but the communication area may be indicated by, for example, the distance from the location of the base station to the outer edge of the communication area, or by latitude and longitude. Furthermore, FIG. 3 stores communication status information indicating whether the base station is in a communication-enabled state (normal) or a communication-disabled state (communication unavailable). In the example of FIG. 3, base station 7 (BS7), base station 8 (BS8), and base station 9 (BS9) are each in a communication-disabled state (communication unavailable). Note that, unlike base stations 7 and 8, base station 9 has no communication abnormality and is active. However, if the reception strength of a wireless signal from a base station is below a preset threshold and sufficient communication quality cannot be obtained, such a base station may be determined to be in a communication-disabled state.

[0035] The communication information extraction unit 105 (corresponding to the "area information extraction unit") of the control unit 104 extracts base station information indicating base stations that the communication device 3 mounted on the mobile body can connect to along a planned travel route, and area information corresponding to the base station information, from the communication information storage unit 103. Hereinafter, of the base stations indicated by the base station information stored in the communication information storage unit 103, base stations that the communication device 3 can connect to along a planned travel route will be referred to as candidate base stations.

[0036] If the communication status information corresponding to a candidate base station indicates that the base station is in a "communication unavailable" state, the communication information extraction unit 105 extracts the base station information of the candidate base stations excluding the candidate base station (corresponding to a "specific base station") that is in a communication unavailable state, and the corresponding area information.

[0037] Here, "unable to communicate" refers not only to a case where the base station is in a state where communication is not possible, but also to a case where the base station is in a state where communication is possible but the quality of communication is not sufficient.

[0038] Fig. 4 is a diagram illustrating the communication areas of candidate base stations. The ovals in Fig. 4 indicate the communication areas (A1 to A7) of the base stations. The communication areas shown in Fig. 4 correspond to the communication areas of the base stations (BS1 to BS7) illustrated in Fig. 3. The straight lines in Fig. 4 indicate the planned route of travel of the vehicle, with S indicating the current position of the vehicle and G indicating the destination of the vehicle. P1 to P8 indicate the points where the planned route intersects with the outer edge of each communication area.

[0039] According to Fig. 4, the planned travel route of the vehicle passes through communication areas A1 to A7. Therefore, the candidate base stations to which the communication device 3 of the vehicle can connect along the planned travel route are base stations BS1 to BS7. However, as shown in Fig. 3, base station BS7 is not activated and is not able to communicate. Therefore, the communication information extraction unit 105 selects base stations BS1 to BS6 excluding base station BS7 as candidate base stations, and extracts base station information indicating base stations BS1 to BS6 and area information indicating communication areas A1 to A6.

[0040] The travel time prediction unit 106 derives an area where two communication areas overlap from among the communication areas indicated by the area information extracted by the communication information extraction unit 105. An area where two communication areas overlap is a handover area where handover from one candidate base station to another candidate base station is possible. Hereinafter, the candidate base station before handover in the handover area will be referred to as the source base station, and the base station to which handover is made will be referred to as the destination base station. The travel time prediction unit 106 further predicts the travel time required for the vehicle to travel the planned travel route included in the handover area.

[0041] In one example, the travel time prediction unit 106 first calculates the distance of the planned travel route included in each handover area. The travel time prediction unit 106 then derives the travel time T [s] (= L / V) predicted to be required for the vehicle to travel the planned travel route included in the handover area based on the calculated distance L [m] and the speed limit V [m / s] of the planned travel route included in the handover area.

[0042] The travel time prediction unit 106 may predict the travel time using the speed of other vehicles currently traveling on the planned travel route or the current vehicle speed instead of the speed limit.

[0043] The travel time prediction process in the travel time prediction unit 106 will be further described with reference to Figures 5 and 6. Figure 5 shows the distances (L1 to L9) between each of the points shown in Figure 4, the speed limits (V1 to V9) between each of the points, and the travel times (T1 to T9) predicted to be required for a vehicle to travel each distance.

[0044] Fig. 6 shows the correspondence between the handover areas of each candidate base station shown in Fig. 4, points on the planned travel route included in the handover area, and the distance and travel time of the planned travel route included in the handover area. In Fig. 6, handover areas where two communication areas overlap are simply indicated using the symbol (∧). For example, the handover area where communication area A1 and communication area A2 overlap is represented as (A1 ∧ A2). Fig. 6 also shows the distance and travel time from the point where the planned travel route intersects with communication areas (A4, A6) including destination (G) that are not handover areas, to destination (G).

[0045] For example, the handover area (A1∧A2) where the communication area A1 of candidate base station BS1 and the communication area A2 of candidate base station BS2 overlap includes points S, P1, P2, and P3 on the planned travel route. Therefore, the distance of the planned travel route included in the handover area (A1∧A2) is the sum (L1+L2+L3) of the distance L1 from point S to point P1, the distance L2 from point P1 to point P2, and the distance L3 from point P2 to point P3. Furthermore, the travel time of the planned travel route included in the handover area (A1∧A2) is the sum (T1+T2+T3) of the travel time T1 from point S to point P1, the travel time T2 from point P1 to point P2, and the travel time T3 from point P2 to point P3.

[0046] The handover information transmitting unit 107 transmits handover information including the base station information extracted by the communication information extracting unit 105 and travel time information indicating the travel time predicted by the travel time predicting unit 106 to the in-vehicle device 2. The handover information may further include area information of the candidate base stations.

[0047] The handover information will be described with reference to Figure 7. Figure 7(a) is a diagram visually representing the candidate base stations indicated by the base station information included in the handover information and the travel time indicated by the travel time information. Figure 7(b) is a diagram expressing Figure 7(a) using matrix A. The arrows shown in Figure 7(a) indicate that handover from one candidate base station to another candidate base station is possible, and the numbers attached to the arrows indicate the travel time within the handover area. The travel times shown in Figures 7(a) and 7(b) correspond to the travel times calculated in Figure 6.

[0048] (2) Configuration of the In-Vehicle Device 2 (Handover Device 150) Next, the configuration of the in-vehicle device 2 of this embodiment will be described with reference to Fig. 2. In this embodiment, the in-vehicle device 2 has the function of a handover device 150. The handover device 150 mainly has a base station selection function and a base station switching function. Fig. 2 illustrates a configuration in which these functions are provided in one device. However, the device having the base station selection function and the device having the base station switching function may be provided in different devices. For example, the communication device 3 may be configured to have a base station switching unit 154, which will be described later.

[0049] The handover device 150 includes a handover information receiving unit 151 , a handover information storage unit 152 , a base station selecting unit 153 , and a base station switching unit 154 .

[0050] The handover information receiving unit 151 receives handover information from the handover information providing device 100. The handover information saving unit 152 saves the handover information received by the handover information receiving unit 151.

[0051] The base station selection unit 153 selects a destination base station to which the communication device 3 will hand over from the source base station, which is one of the candidate base stations, based on the handover information stored in the handover information storage unit 152. Specifically, the base station selection unit 153 selects, based on the travel time indicated by the travel time information, the candidate base station with the longest travel time from among other candidate base stations to which the communication device 3 can hand over from the source base station, as the destination base station to which the communication device 3 will connect next after the source base station. The base station selection unit 153 then repeatedly performs the selection process of the destination base station from the source base station whose communication area includes the current location of the vehicle (corresponding to the "first point") until it selects the destination base station whose communication area includes the destination of the vehicle (corresponding to the "second point"). The selection process of the destination base station in the base station selection unit 153 will be described with reference to FIG. 7(a).

[0052] 7(a), when the source base station is base station 1, the candidate base stations to which base station 1 can perform handover are base station 2, base station 3, and base station 4, and the travel times to their respective handover areas are 18, 10, and 4. Therefore, the base station selection unit 153 selects base station 2, which has the longest travel time among the candidate base stations, as the destination base station to which base station 1 will perform handover.

[0053] Next, the base station selection unit 153 sets base station 2, which is the selected destination base station, as the next source base station, and selects a destination base station from among the candidate base stations (base station 3, base station 4, and base station 5) that can be handed over from base station 2. In this example, the travel times between the handover areas of base station 2 and base station 3, base station 4, and base station 5 are 13, 7, and 2, respectively, and base station 3 is the base station with the longest travel time. Therefore, the base station selection unit 153 selects base station 3 as the destination base station for handover from base station 2.

[0054] Similarly, the base station selection unit 153 sets base station 3, which is the selected destination base station, as the next source base station, and selects a destination base station from among the candidate base stations (base station 4, base station 5, and base station 6) that can be handed over from base station 3. In this example, base station 4, which takes the longest travel time within the handover area, is selected as the destination base station for handover from base station 3.

[0055] Here, the communication area of ​​base station 4, which is the selected destination base station, includes point G. Therefore, base station selection unit 153 ends the destination base station selection process.

[0056] FIG. 8 shows the same handover information as FIG. 7(a), but the destination base station selected by the base station selection unit 153 and the handover from the source base station to the destination base station are shown in bold.

[0057] In this embodiment, the planned travel route is a route from the current position (point S) of the vehicle to the destination (point G), and the base station selection unit 153 pre-selects a destination base station for handover from point S to point G. However, the base station selection unit 153 may be configured to sequentially select destination base stations as the vehicle moves.

[0058] When the vehicle moves into the handover area of ​​the selected destination base station, the base station switching unit 154 hands over the base station to which the communication device 3 is connected from the source base station to the destination base station. Whether the vehicle has moved into the handover area may be determined based on vehicle location information. For example, when vehicle location information acquired from a GPS or the like installed in the vehicle indicates that the vehicle is within the range indicated by the area information of the destination base station, it may be determined that the vehicle has moved into the handover area. Alternatively, it may be determined that the vehicle has moved into the handover area when the communication device 3 receives radio waves from the base station.

[0059] It is also possible that the base station switching unit 154 attempts to perform a handover from the source base station to the destination base station, but is unable to perform the handover to the destination base station. For example, the destination base station may have been active when the handover information was received from the server device 1, but may subsequently stop operating. In such a case, the base station selecting unit 153 reselects a new destination base station based on the handover information.

[0060] (3) Operation of handover system 1 The operations of the handover information providing device 100 and the handover device 150 will be described below using the flowcharts in Figures 9 and 10. These processes are not limited to the order shown in Figures 9 and 10. In other words, the order may be changed as long as there are no constraints, such as a relationship in which a step uses the result of a previous step. The same applies to the flowcharts of the embodiments described later.

[0061] The route acquisition unit 101 of the handover information providing device 100 acquires route information indicating a planned future travel route of the vehicle (S101). The communication information extraction unit 105 extracts, from the communication information storage unit 103, base station information indicating candidate base stations that can be connected to along the planned travel route indicated by the route information acquired by the communication device 3 in S101, and area information indicating the communication area of ​​the candidate base station (S102). The travel time prediction unit 106 predicts the travel time required for the vehicle to travel along a planned travel route included in a handover area where the communication area of ​​one candidate base station overlaps with the communication area of ​​another candidate base station among the communication areas indicated by the area information extracted in S102 (S103). Then, the handover information transmitting unit 107 transmits handover information including the base station information extracted in S102 and travel time information indicating the travel time predicted in S103 to the in-vehicle device 2 (S104).

[0062] The handover information receiving unit 151 of the handover device 150 provided in the in-vehicle device 2 receives the handover information transmitted in S104 (S151). The handover information storage unit 152 stores the handover information received in S151 (S152). The base station selection unit 153 selects a destination base station to be handed over from the source base station based on the travel time information included in the handover information stored in S152 (S153). The destination base station selection process will be described later with reference to FIG. If the vehicle moves into the handover area (S154: Y), the base station switching unit 154 hands over the base station to which the communication device 3 is connected from the source base station to the destination base station selected in S153 (S155).

[0063] Also, in S104, if communication status information is received after transmitting handover information to the in-vehicle device 2 (S105), the communication information storage unit 103 updates the stored communication status information (S106). Then, if the updated communication state information indicates that a particular base station is not capable of communication (S107: Y), candidate base stations excluding the base station that is not capable of communication are extracted again (S102).

[0064] Next, the destination base station selection process of S153 will be described with reference to FIG. First, one of the candidate base stations whose communication area includes point S is selected as the source base station (S1531). Next, among the candidate base stations whose communication area overlaps with the communication area of ​​the source base station selected in S1531, the candidate base station with the longest travel time is selected as the destination base station (S1532). Here, if point G is included in the communication area of ​​the destination base station selected in S1532 (S1533: Y), the base station selection process ends. On the other hand, if the communication area of ​​the destination base station selected in S1532 does not include point G, the destination base station selected in S1532 is set as the next source base station, and the next source base station selects the destination base station to hand over to (S1532). Then, the process of selecting the destination base station (S1532 to S1534) is repeatedly executed until point G is included in the communication area of ​​the destination base station selected in S1532.

[0065] It should be noted that the vehicle's travel route may change midway after the destination base station is selected by the process shown in Fig. 9. In such a case, route information indicating the planned travel route after the change is acquired in S101, and the process shown in Fig. 9 is executed again.

[0066] (4) When the communication device has multiple communication modules Next, in this embodiment, a case where the communication device 3 has multiple communication modules will be described. When the communication device 3 has multiple communication modules, the communication modules may use the same communication method or may use different communication methods. Each case will be described below.

[0067] (a) When multiple communication modules use different communication methods A case will be described in which multiple communication modules included in the communication device 3 each use a different communication method. As an example, a case will be described in which one of two communication modules included in the communication device 3 can communicate using Wi-Fi and the other can communicate using 4G. In this example, candidate base stations are extracted for each of the Wi-Fi and 4G communication methods, and travel times within each handover area are predicted, and a destination base station is selected based on the travel times.

[0068] When the communication methods are different, not only the base station to which the communication device 3 connects but also the communication area in which the base station can communicate differs. Therefore, it is necessary to select a different base station to connect to for each communication method.

[0069] The same applies when the communication device 3 uses multiple cellular lines operated by different telecommunications carriers. Each telecommunications carrier installs its own base station for the cellular lines. Therefore, the base station and communication area to which the communication device 3 connects are different for each cellular line operated by a different telecommunications carrier.

[0070] (b) When multiple communication modules use the same communication method Next, a case will be described in which the same communication method is used by multiple communication modules included in the communication device 3. In this embodiment, a case in which there are two communication modules is described as an example, but the communication device 3 may have three or more communication modules.

[0071] The following description will be given taking as an example a case where the communication device 3 has a first communication module that communicates using a first communication line and a second communication module that communicates using a second communication line. Since the first communication line and the second communication line use the same communication method, the communication device 3 can communicate with the source base station and the destination base station using either the first communication line or the second communication line.

[0072] As an example, the base station selection unit 153 selects the same destination base station for the first communication module and the second communication module. That is, the base station selection unit 153 selects the candidate base station with the longest travel time as the destination base station to be connected via the first communication line and the second communication line.

[0073] In this case, the base station switching unit 154 performs a handover from the source base station to the destination base station using the first communication line, and then performs a handover from the source base station to the destination base station using the second communication line.

[0074] During handover, communication using the communication module performing the handover becomes temporarily unavailable. Therefore, while handover is being performed on one communication line, the other communication line continues communication by connecting to the source base station, and after handover of one communication line is completed, handover is performed on the other communication line, and the communication line that completed handover first connects to the destination base station and continues communication. This makes it possible to prevent communication from being interrupted while handover is being performed.

[0075] As another example, the base station selection unit 153 selects different destination base stations for the first communication module and the second communication module. Selection of destination base stations for the first communication line and the second communication line in this example will be described with reference to Fig. 11.

[0076] Figure 11 shows the same handover information as Figure 7(a). Point S is included in the communication areas of base station 1 and base station 2. Therefore, base station 1 (corresponding to the "first source base station") is selected as the base station to connect to first using the first communication line, and base station 2 (corresponding to the "second source base station") is selected as the base station to connect to first using the second communication line. Figure 11(a) shows base stations to connect to using the first communication line with solid lines and base stations to connect to using the second communication line with dashed lines.

[0077] After base station selection unit 153 selects base station 1 and base station 2, it then first selects as the next destination base station the base station with the longest travel time among the travel time between the handover areas of base station 1 and the other candidate base stations and the travel time between the handover areas of base station 2 and the other candidate base stations. However, at this time, it does not select a base station that has already been selected as the destination base station.

[0078] 11, the longest travel time among the travel time between base station 1 and the other candidate base stations (base station 3, base station 4) and the travel time between base station 2 and the other candidate base stations (base station 3, base station 4) is the travel time (13) from base station 2 to base station 3. Therefore, base station 3 (corresponding to the "second destination base station") is selected as the destination base station for handover from base station 2 using communication line 2.

[0079] Next, a destination base station for handover from base station 1 is selected using communication line 1, but base stations 2 and 3 have already been selected. Therefore, base station 4 (corresponding to the "first destination base station") is selected as the destination base station for handover from base station 1 using communication line 1. Here, the communication area of ​​base station 4 includes point G. Therefore, the process of selecting a destination base station for communication line 1 is terminated (see FIG. 11(b)).

[0080] Meanwhile, in communication line 2, of base stations 5 and 6, which are candidate base stations excluding base station 4, base station 5, which has the longest travel time, is selected as the destination base station for handover from base station 3. Next, since base station 6 is the only candidate base station to which base station 5 can handover, base station 6 is selected as the destination base station for handover from base station 5. The communication area of ​​base station 6 includes point G. Therefore, the process of selecting a destination base station in communication line 2 is terminated (see FIG. 11(c)).

[0081] In this example, the base station connectable via communication line 1 is the same as the base station connectable via communication line 2. However, as shown in Fig. 11, different base stations are selected as destination base stations for communication line 1 and communication line 2 when performing handover.

[0082] If the timing of handovers for communication line 1 and communication line 2 overlap, it is desirable to complete the handover for one communication line before completing the handover for the other communication line. This is because if two communication lines perform handovers at the same time, communication will be interrupted. In this case, it is desirable to prioritize the handover with the longer travel time so that the handover for at least one of the two communication lines is completed reliably.

[0083] 12 is a diagram illustrating another embodiment. In this example, if the mobile station does not connect to base station 5 and base station 7 before moving from point S to point G on the planned travel route, a communication interruption will occur. In such a case, both the first communication line and the second communication line may be connected to base station 5 and base station 7.

[0084] In the same manner as in Fig. 11, the base station selection unit 153 selects candidate base stations to connect to via communication line 1 and communication device 2. In Fig. 12(b), the candidate base stations to connect to via communication line 1 are indicated by thick lines, and in Fig. 12(c), the candidate base stations to connect to via communication line 2 are indicated by thick lines. As shown in Fig. 12(b) and Fig. 12(c), both communication line 1 and communication device 2 have selected base station 5 and base station 7 as the candidate base stations to connect to.

[0085] In addition, in communication line 1, base station selection unit 153 selects base station 7 (corresponding to the "first destination base station") with the longest travel time as the destination base station for handover from base station 5, and in communication line 2, selects base station 6 (corresponding to the "second destination base station") with the second longest travel time. In this way, even if the source base station is the same, the destination base stations to be connected to in communication lines 1 and 2 are selected to be different.

[0086] (5) Summary As described above, according to this embodiment, by selecting the base station that will result in the longest travel time within the handover area from among multiple candidate base stations and performing the handover, it is possible to achieve base station handover even when the communication device is mounted on a mobile body that moves at high speed.

[0087] Furthermore, in this embodiment, high-load processing such as deriving travel time can be performed by the server device 1. Furthermore, the in-vehicle device 2 receives handover information from the server device 1 and selects a destination base station, so that even if connection to the intended destination base station cannot be established, the in-vehicle device 2 can immediately select another destination base station based on the handover information.

[0088] 3. Embodiment 2 In the first embodiment, the in-vehicle device 2 has a function of selecting a base station to connect to. In this embodiment, a configuration in which the server device 1 has a function of selecting a base station to connect to will be described. Below, differences from the first embodiment will be described, and the same configurations and processes as those in the first embodiment will be denoted by the same reference numerals in the drawings, and the description of the first embodiment will be quoted.

[0089] (1) Configuration of Server Device 1 (Handover Instruction Device 200) The configuration of the server device 1 of this embodiment will be described with reference to Fig. 13. In this embodiment, the server device 1 has a function as a handover instruction device 200.

[0090] The handover instruction device 200, which is the server device 1, includes a route acquisition unit 101, a communication status acquisition unit 102, a communication information storage unit 103, a control unit 204, and a handover instruction transmission unit 202. The control unit 204 implements a communication information extraction unit 105, a travel time prediction unit 106, and a base station selection unit 201. The main difference from the server device 1 of the first embodiment is that in this embodiment, the server device 1 includes the base station selection device 201 and transmits handover instruction information instead of handover information.

[0091] The base station selection unit 201 selects a destination base station based on the base station information extracted by the communication information extraction unit 105 and the travel time for handover of each candidate base station predicted by the travel time prediction unit 106. The method by which the base station selection unit 201 selects a destination base station is the same as in the first embodiment.

[0092] The handover instruction transmitting unit 202 transmits handover instruction information to the in-vehicle device 2 to instruct the in-vehicle device 2 to perform handover to the destination base station selected by the base station selecting unit 201 .

[0093] The handover instruction transmitter 202 may transmit handover instruction information including all of the base station information indicating all of the destination base stations connected along the planned travel route. When the base station selector 201 selects the destination base stations shown in Fig. 8, the handover instruction information includes, for example, information indicating base station 1, base station 2, base station 3, and base station 4 in Fig. 8, and instruction information instructing to perform handover in this order.

[0094] Alternatively, the handover instruction information may include only base station information indicating a destination base station to which communication device 3 is to connect next after the base station currently connected, and instruction information instructing to execute handover to the destination base station. In this case, for example, after execution of handover from the source base station to the destination base station in communication device 3 is completed, handover instruction transmitter 202 transmits, to in-vehicle device 2, base station information indicating a next destination base station to which communication device 3 is to handover from the destination base station (i.e., the next source base station) and instruction information to execute handover to the destination base station, through communication via the destination base station. In the example of FIG. 8, after communication device 3 completes handover from base station 1 to base station 2, handover instruction information including base station information indicating the next destination base station, i.e., base station 3, and instruction information instructing to handover to base station 3 is transmitted to in-vehicle device 2 through communication via base station 2.

[0095] (2) Configuration of the In-Vehicle Device 2 (Handover Device 250) Next, the configuration of the in-vehicle device 2 of this embodiment will be described with reference to Fig. 13. In this embodiment, the in-vehicle device 2 has a function as a handover device 250.

[0096] The handover device 250, which is the in-vehicle device 2, has a handover instruction receiving unit 251 and a base station switching unit 154. The difference from the in-vehicle device 2 of the first embodiment is that the in-vehicle device 2 of this embodiment does not have a base station selection function.

[0097] The handover instruction receiving unit 251 receives handover instruction information from the server device 200. The base station switching unit 154 performs handover from the source base station to which the communication device 3 is connected to the destination base station instructed by the handover instruction information received by the handover instruction receiving unit 251.

[0098] (3) Operation of handover system 1 The operations of the handover instruction device 200 and the handover device 250 will be described with reference to the flowchart of FIG.

[0099] The base station selection unit 201 of the handover instruction device 200 selects a destination base station based on the travel time predicted in S103 (S201). In S201, the destination base station selection process described in FIG. 10 is executed. The handover command transmitting unit 202 transmits handover command information to the handover device 250, instructing the handover to the destination base station selected in S201 (S202).

[0100] The handover instruction receiving unit 251 of the handover device 250 receives handover instruction information from the handover instruction device 200 (S251). Then, when the vehicle moves into the handover area between the source base station and the destination base station included in the handover instruction information (S154), the base station switching unit 154 performs a handover from the source base station to the destination base station (S155).

[0101] (4) Summary As described above, according to this embodiment, in addition to predicting travel time, the server device 1 can select a connection source base station, and the processing involved in handover in the vehicle-mounted device 2 can be further reduced.

[0102] 4. Embodiment 3 In the first and second embodiments, the server device 1 is configured to extract base station information and communication area information. In this embodiment, a configuration will be described in which the in-vehicle device 2 performs handover processing, destination base station selection processing, and base station information and communication area information extraction processing. That is, in this embodiment, all processing of the handover system S is performed by the in-vehicle device 2. Below, differences from the first embodiment will be described, and configurations and processing similar to those of the first embodiment will be denoted by the same reference numerals in the drawings, and the description of the first embodiment will be quoted.

[0103] (1) Configuration of the In-Vehicle Device 2 (Handover Device 350) The configuration of the in-vehicle device 2 of this embodiment will be described with reference to Fig. 15. In this embodiment, the in-vehicle device 2 has a function as a handover device 350.

[0104] The handover device 350, which is the in-vehicle device 2, includes a route acquisition unit 351, a communication status acquisition unit 352, a communication information storage unit 353, a control unit 354, and a base station switching unit 154. The control unit 354 realizes a communication information extraction unit 355, a travel time prediction unit 356, and a base station selection unit 153.

[0105] The configurations and processes of the route acquisition unit 351, communication status acquisition unit 352, communication information storage unit 353, communication information extraction unit 355, and travel time prediction unit 356 of the handover device 350 are the same as those of the route acquisition unit 101, communication status acquisition unit 102, communication information storage unit 103, communication information extraction unit 105, and travel time prediction unit 106 in the first and second embodiments. However, while these configurations are provided in the server device 1 in the first embodiment, they are provided in the in-vehicle device 2 in the present embodiment.

[0106] In the first and second embodiments, the communication status acquisition unit 102 provided in the server device 1 acquires communication status information of base stations from base stations and vehicles. However, if the communication status acquisition unit 352 is provided in a vehicle, it is difficult to acquire communication status information from base stations to which the vehicle cannot connect, and there is a risk that communication status information of base stations located far away from the current location of the vehicle cannot be acquired from other vehicles. Therefore, in the present embodiment, the communication status acquisition unit 352 may not be provided, or communication status information and handover record information may be received from a server device that collects communication status information from base stations and vehicles.

[0107] (2) Operation of handover system 1 The operation of the handover device 350 will be described with reference to the flowchart of FIG.

[0108] The route acquisition unit 351 of the handover device 350 acquires route information indicating a planned route of the vehicle (S301). The communication information extraction unit 352 extracts, from the communication information storage unit 353, base station information indicating candidate base stations that can be connected to along the planned travel route indicated by the route information acquired in S301, and area information indicating the communication area of ​​the candidate base station (S302). The travel time prediction unit 356 predicts the travel time required for the vehicle to travel along the planned travel route included in the handover area where the communication area of ​​one candidate base station overlaps with the communication area of ​​another candidate base station among the communication areas indicated by the area information extracted in S302 (S303). The base station selection unit 153 selects, from the candidate base stations, a destination base station to which the communication device 3 will be handed over from the source base station, based on the travel time predicted in S303 (S153). In S153, the destination base station selection process described in FIG. 10 is executed.

[0109] Furthermore, in S153, if communication status information is received after selecting a destination base station (S304: Y), the communication information storage unit 103 updates the stored communication status information (S305). Then, if the updated communication state information indicates that a specific base station is not capable of communication (S306: Y), candidate base stations excluding the specific base station that is not capable of communication are extracted again (S302).

[0110] Then, when the vehicle moves into the handover area (S154: Y), the base station switching unit 154 hands over the base station to which the communication device 3 is connected from the source base station to the destination base station selected in S153 (S155).

[0111] (3) Summary As described above, according to this embodiment, not only the handover process but also the travel time prediction and the destination base station selection process are performed by the in-vehicle device 2. In this embodiment, although the processing load of the in-vehicle device 2 increases, the amount of communication with the server device 1 can be reduced.

[0112] 5. Variation 1 In the above-described embodiments, the candidate base station with the longest travel time within the handover area is determined as the destination base station. In this modification, a candidate base station other than the candidate base station with the longest travel time is selected as the destination base station.

[0113] (1) Selection of the base station to connect to This modification will be described with reference to Figures 17 and 18. Figure 17 schematically shows the communication areas (B1 to B6) of the candidate base stations. Figure 18 visually shows the travel time between the candidate base stations and the handover areas of their communication areas shown in Figure 17.

[0114] When the travel time in the handover area of ​​each communication area shown in Fig. 17 is the travel time shown in Fig. 18(a), selecting a destination base station using the methods of the first to third embodiments results in the result shown in Fig. 18(b). That is, base stations 1 to 6 are all selected as destination base stations. However, when the frequency of handover is high like this, the processing load related to handover increases.

[0115] Therefore, as shown in Figure 18(b), if selecting the candidate base station with the longest travel time as the destination base station would increase the frequency of handovers, specifically if the total number of destination base stations selected from point S (corresponding to the "first point") to point G (corresponding to the "second point") on the planned travel route is greater than a predetermined threshold, the destination base station is selected so that the total number of destination base stations is "less than" the predetermined threshold.

[0116] Here, "greater than or equal to" and "less than or equal to" include both cases where the value is the same as the comparison target and cases where it is not.

[0117] However, the travel time between the handover areas of the destination base station and the source base station must be longer than the time required to complete the handover process. Therefore, it is desirable to select the destination base station so that the travel time between the handover areas of the destination base station and the source base station is "longer" than a predetermined time.

[0118] For example, the actual handover time required for a handover from a source base station to a destination base station is set as the predetermined time. When the communication status acquisition unit (102, 352) of each embodiment acquires handover record information indicating the actual handover time required for another vehicle to perform a handover from a source base station to a destination base station, the handover record information is stored in the communication information storage unit (103, 353). Therefore, the base station selection unit (153, 201) sets the handover time indicated by the handover record information stored in the communication information storage unit (103, 353) as the predetermined time, and selects a destination base station so that the handover time is equal to or greater than the predetermined time. With this configuration, it is possible to reduce the total number of destination base stations on the planned travel route while ensuring the travel time required for handover.

[0119] Alternatively, instead of the actual handover time, a predetermined time may be set in advance.

[0120] An example of base station selection in this modification is shown in Figure 18(c). In this example, it is assumed that handover in each handover area takes 4 seconds, and the predetermined time is set to 4. It is also assumed that the threshold for the number of destination base stations is set to 5.

[0121] The number of destination base stations selected in Figure 18(b) is 6, and the total number of destination base stations is greater than the threshold. Therefore, in Figure 18(c), base station 3 is not selected as the destination base station for handover from base station 2, and base station 4 is selected instead. The total number of destination base stations selected in Figure 18(c) is 5, which is less than the threshold.

[0122] Here, in order to reduce the number of destination base stations on the planned movement route, for example, base station 3 can be selected as the destination base station for handover from base station 1, and base station 5 can be selected as the destination base station for handover from base station 2. However, the travel time between the handover areas of base station 1 and base station 3 is 3, and the travel time between the handover areas of base station 2 and base station 5 is 1, and these travel times are less than a predetermined time (4). Therefore, base station 3 is not selected as the destination base station for handover from base station 1, and base station 5 is not selected as the destination base station for handover from base station 2.

[0123] 18, for ease of explanation, the number of destination base stations from the current position of the vehicle to the destination has been described. However, it may be the total number of destination base stations from any point on the planned travel route to another any point. Alternatively, a threshold value for the number of base stations per predetermined distance (e.g., 1 km) on the planned travel route may be set in advance, and the threshold value may be set according to the total distance of the planned travel route.

[0124] (2) Operation of the base station selector Next, the operation of the base station selection unit (153, 201) in this modified example will be described with reference to Fig. 19. Note that the processing shown in Fig. 19 is processing executed in place of Fig. 10 at S153 in Fig. 9 and Fig. 16 and S201 in Fig. 14.

[0125] The processing in steps S1531 to S1534 is the same as that in FIG. In this modified example, if the communication area of ​​the selected destination base station includes point G (S1533: Y), it is determined whether the total number of destination base stations selected from point S to point G is less than or equal to a threshold (S1535). Here, if the total number of destination base stations is equal to or less than the threshold value, the process ends (S1535: Y). On the other hand, if the total number of destination base stations is greater than the threshold (S1535:N), another destination base station whose communication area includes point S and whose handover area travel time is greater than or equal to the predetermined time is selected again, and the processes of S1533, S1534, and S1532 are repeated.

[0126] (3) Summary According to this modification, when multiple communication areas overlap on the planned travel route, it is possible to select a destination base station that can secure the time required for handover processing while preventing frequent handovers.

[0127] 6. Variation 2 In the above-described embodiments, a configuration has been described in which the candidate base station with the longest travel time is selected as the destination base station. However, even if the destination base station with the longest travel time is selected, the travel time within the handover area may be shorter than the time required for the handover process. In this modification, a description will be given of vehicle speed control in such a case.

[0128] Fig. 20 is a diagram illustrating a configuration example of an in-vehicle device 2 to which this modified example is applied. The in-vehicle device 2 of this modified example has a speed control function. Note that Fig. 20 illustrates a case in which this modified example is applied to the in-vehicle device 2 of embodiment 1, but this modified example may also be applied to the in-vehicle devices 2 of embodiments 2 and 3, or the server device 1 of embodiment 2 may be provided with a speed control function.

[0129] The handover device 150 shown in FIG. 20 includes a speed determination unit 155 and a speed instruction unit 156 in addition to the components shown in the first embodiment.

[0130] In this modified example, the handover information received by the handover information receiving unit 151 includes, in addition to base station information and travel time information, handover performance information indicating the handover time required for handover from one candidate base station indicated by the base station information to another candidate base station.

[0131] As explained in the first to third embodiments, the base station selection unit 153 in this modification selects, as the destination base station, the base station with the longest travel time among the candidate base stations.

[0132] Here, if the travel time in the handover area between the destination base station and the source base station selected by the base station selection unit 153 is shorter than the handover information indicated by the handover record information, the speed determination unit 155 determines the speed at which the vehicle will travel along the planned travel route included in the handover area so that the travel time is longer than the handover time.

[0133] For example, if the distance of the planned travel route included in the handover area between the communication area A1 of the base station 1 and the communication area A2 of the base station 2 is L, 12 [m], and the speed limit in the handover area is V 12 In this case, the estimated travel time T 12 [s] is L 12 / V 12 is.

[0134] Here, it is assumed that the handover record information indicates that the handover time required for handover from base station 1 to base station 2 is T [s]. 12 If T>T, the communication device 3 can complete handover from the base station 1 to the base station 2 in the handover area. 12 In this case, the communication device 3 cannot complete the handover from the base station 1 to the base station 2 while moving through the handover area. Therefore, the speed determination unit 155 determines whether T≦T 12 The vehicle speed is determined so that

[0135] Specifically, the vehicle speed is V x Then, T≦L 12 / V x If V is satisfied, the handover can be completed in the handover area. x ≦L 12 Speed ​​V to fill / T x is determined as the speed of the vehicle.

[0136] The speed indication unit 156 outputs speed information indicating the speed determined by the speed determination unit 155 to, for example, an electronic control unit that controls the speed of the vehicle.

[0137] When the speed determination function is provided in the server device 1 of the second embodiment, the speed information is transmitted to the vehicle-mounted device 1 together with the handover command information.

[0138] In addition, when a vehicle has multiple communication lines, the speed of the vehicle may be determined so that all of the multiple communication lines can be handed over in the handover area. For example, in the above example, since the time required for two communication lines to complete handover in the handover area is 2T [s], the speed determination unit 155 determines whether 2T≦T 12 Therefore, the speed determination unit 155 determines the vehicle speed so that V x ≦L 12 Speed ​​V that satisfies / 2T x is determined as the speed of the vehicle.

[0139] Alternatively, the speed of the vehicle may be determined so that only one of the multiple lines can be handed over.

[0140] According to this modification, the speed of the vehicle is determined, and the vehicle travels through the handover area at the determined speed, thereby making it possible to complete the handover from the source base station to the destination base station.

[0141] 7. Summary The features of the handover system and the like in each embodiment of the present invention have been described above.

[0142] The terms used in each embodiment are merely examples and may be replaced with synonymous terms or terms having the same functions.

[0143] The block diagrams used to explain the embodiments classify and organize the device configuration by function. The blocks representing each function can be realized by any combination of hardware or software. Furthermore, because they represent functions, the block diagrams can also be understood as disclosures of method inventions and program inventions that realize the methods.

[0144] The order of the functional blocks that can be understood as the processes, flows, and methods described in each embodiment may be changed as long as there are no constraints, such as one step utilizing the results of another step that precedes it.

[0145] The terms first, second, through Nth (N is an integer) used in each embodiment and in the claims are used to distinguish between two or more configurations or methods of the same type, and do not limit the order or superiority or inferiority.

[0146] Moreover, examples of the configuration of each device constituting the handover system of the present invention include the following. Examples of the component include semiconductor elements, electronic circuits, modules, and microcomputers. Examples of semi-finished products include an electronic control unit (ECU) and a system board. Finished product forms include mobile phones, smartphones, tablets, personal computers (PCs), workstations, and servers. Other examples include devices with communication functions, such as video cameras, still cameras, and car navigation systems.

[0147] Furthermore, necessary functions such as an antenna and a communication interface may be added to each device that constitutes the handover system.

[0148] The present invention can be realized not only by dedicated hardware having the configuration and functions described in each embodiment, but also by a combination of a program for realizing the present invention recorded on a recording medium such as a memory or hard disk, and general-purpose hardware having a dedicated or general-purpose CPU and memory that can execute the program.

[0149] A program stored in a non-transitory physical recording medium (for example, an external storage device (hard disk, USB memory, CD / BD, etc.) or an internal storage device (RAM, ROM, etc.)) of dedicated or general-purpose hardware can be provided to the dedicated or general-purpose hardware via a recording medium, or via a communication line from a server without using a recording medium. This makes it possible to always provide the latest functions through program upgrades. [Industrial Applicability]

[0150] The present invention is primarily directed to a method for handing over a base station connected to a communication device mounted on an automobile, but may also be directed to a handover method for a communication device mounted on any mobile body other than an automobile. [Explanation of symbols]

[0151] S handover system, 150,350 handover device, 101,351 route acquisition unit, 103,353 communication information storage unit, 105,355 communication information extraction unit, 106,356 travel time prediction unit, 153,201 base station selection unit, 154 base station switching unit

Claims

1. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101, S301), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which the communication device can connect to along the planned travel route is extracted (S102, S302). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted to be included in the handover area where a handover from the source base station to the other candidate base station is possible (S103, S303). Based on the aforementioned travel time, the communication device selects a destination base station from the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the base station to which the communication device is connected is handed over from the source base station to the destination base station (S155). The destination base station is the candidate base station with the longest travel time among the other candidate base stations. Handover method.

2. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101, S301), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which the communication device can connect to along the planned travel route is extracted (S102, S302). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted to be included in the handover area where a handover from the source base station to the other candidate base station is possible (S103, S303). Based on the aforementioned travel time, the communication device selects a destination base station from the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the base station to which the communication device is connected is handed over from the source base station to the destination base station (S155). The communication device and the source base station and the destination base stations, namely the first and second destination base stations, can communicate using the first and second communication lines, which use the same communication method. The first destination base station is the candidate base station with the longest travel time among the other candidate base stations, and the second destination base station is the candidate base station with the second longest travel time among the other candidate base stations. A handover is performed from the source base station to the first destination base station using the first communication line, and a handover is performed from the source base station to the second destination base station using the second communication line. Handover method.

3. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101, S301), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which the communication device can connect to along the planned travel route is extracted (S102, S302). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted to be included in the handover area where a handover from the source base station to the other candidate base station is possible (S103, S303). Another communication device, different from the aforementioned communication device, acquires handover performance information indicating the handover time required for the handover from the source base station to the other candidate base station. Based on the aforementioned travel time, the communication device selects a destination base station from the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the base station to which the communication device is connected is handed over from the source base station to the destination base station (S155). The aforementioned planned travel route is the route from point 1 to point 2. The process of selecting the next destination base station to be the next source base station, and selecting the next destination base station to hand over from the next source base station, is repeatedly performed from the source base station, which includes the first point in the communication area, until the destination base station, which includes the second point in the communication area, is selected. The destination base station is selected such that the total number of destination base stations selected from the first point to the second point is less than or equal to a threshold, and the travel time between the handover area of ​​the source base station and the destination base station is equal to or greater than the handover time. Handover method.

4. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101, S301), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which the communication device can connect to along the planned travel route is extracted (S102, S302). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted to be included in the handover area where a handover from the source base station to the other candidate base station is possible (S103, S303). Based on the aforementioned travel time, the communication device selects a destination base station from the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the base station to which the communication device is connected is handed over from the source base station to the destination base station (S155). The handover method further includes: Another communication device, different from the aforementioned communication device, acquires handover performance information indicating the handover time required for the handover from the source base station to the destination base station. If the travel time within the handover area between the source base station and the destination base station is shorter than the handover time, the speed at which the moving object travels along the planned route included in the handover area is determined so that the travel time becomes equal to or greater than the handover time. Output speed information indicating the determined speed. Handover method.

5. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101, S301), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which the communication device can connect to along the planned travel route is extracted (S102, S302). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted to be included in the handover area where a handover from the source base station to the other candidate base station is possible (S103, S303). Based on the aforementioned travel time, the communication device selects a destination base station from the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the base station to which the communication device is connected is handed over from the source base station to the destination base station (S155). The handover method further includes a process for receiving communication status information indicating the communication status of the base station, If the aforementioned communication status information indicates that a specific base station is unable to communicate, the area information of the candidate base stations excluding the specific base station is extracted. Handover method.

6. A handover method for a communication device mounted on a mobile device to switch to a base station, The future planned movement path of the moving object is obtained (S101), From the communication information storage unit which stores area information indicating the communication area in which the base station can communicate, the area information of candidate base stations which are base stations that the communication device can connect to along the planned travel route is extracted (S102). Among the communication areas indicated by the extracted area information, the communication area of ​​one candidate base station, which is the source base station, and the communication areas of other candidate base stations overlap, and the travel time required for the mobile body to travel along the planned travel route is predicted in the handover area that is included in the handover area where a handover from the source base station to the other candidate base station is possible (S103). The communication device is sent handover information including travel time information indicating the travel time and base station information indicating the candidate base station (S104). The mobile unit receives the handover information (S151), In the aforementioned mobile unit, based on the travel time, the communication device selects a destination base station from among the other candidate base stations to which it will hand over from the source base station (S153), When the mobile body moves to the handover area, the communication device hands over the base station to which it is connected from the source base station to the destination base station (S155). Handover method.

7. The communication device and the source base station and the destination base station can communicate using a first communication line and a second communication line that use the same communication method. After a handover is performed from the source base station to the destination base station using the first communication line, a handover is performed from the source base station to the destination base station using the second communication line. The handover method according to claim 1, 3, 4, 5, or 6.

8. The communication device and the first and second source base stations, which are the source base stations, and the second and second source base stations, which are the destination base stations, can communicate using the first and second communication lines, which use the same communication method. A handover is performed from the first source base station to the first destination base station using the first communication line. A handover is performed from the second source base station to the second destination base station using the second communication line. The handover method according to claim 1, 3, 4, 5, or 6.

9. Based on the distance and speed limit of the planned travel route included in the handover area, the travel time is predicted. The handover method according to any one of claims 1 to 6.

10. The handover method further includes: The communication device is sent handover instruction information instructing the destination base station to perform a handover (S202). The mobile unit receives the handover instruction information (S251). Including processing, In the aforementioned mobile device, a handover is performed from the source base station to the destination base station based on the handover instruction information. The handover method according to any one of claims 1 to 5.

11. The handover method is performed on the mobile body. The handover method according to any one of claims 1 to 5.

12. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, A route acquisition unit (101, 351) acquires the planned future movement path of the aforementioned moving object, Area information extraction unit (105, 355) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route from the communication information storage unit (103, 353) which stores area information indicating the communication area in which the base station can communicate, A travel time prediction unit (106, 356) predicts the travel time required for the mobile body to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. Based on the aforementioned travel time, a base station selection unit (153, 201) selects from among the other candidate base stations the communication device will use to hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The destination base station is the candidate base station with the longest travel time among the other candidate base stations. Handover system (S).

13. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, A route acquisition unit (101, 351) acquires the planned future movement path of the aforementioned moving object, Area information extraction unit (105, 355) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route from the communication information storage unit (103, 353) which stores area information indicating the communication area in which the base station can communicate, A travel time prediction unit (106, 356) predicts the travel time required for the mobile body to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. Based on the aforementioned travel time, a base station selection unit (153, 201) selects from among the other candidate base stations the communication device will use to hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The communication device and the source base station and the destination base stations, namely the first and second destination base stations, can communicate using the first and second communication lines, which use the same communication method. The first destination base station is the candidate base station with the longest travel time among the other candidate base stations, and the second destination base station is the candidate base station with the second longest travel time among the other candidate base stations. The base station switching unit performs a handover from the source base station to the first destination base station using the first communication line, and a handover from the source base station to the second destination base station using the second communication line. Handover system (S).

14. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, A route acquisition unit (101, 351) acquires the planned future movement path of the aforementioned moving object, Area information extraction unit (105, 355) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route from the communication information storage unit (103, 353) which stores area information indicating the communication area in which the base station can communicate, A travel time prediction unit (106, 356) predicts the travel time required for the mobile body to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. A communication status acquisition unit (102, 352) acquires handover performance information indicating the handover time required for a communication device other than the aforementioned communication device to hand over from the source base station to the other candidate base station, Based on the aforementioned travel time, a base station selection unit (153, 201) selects from among the other candidate base stations the communication device will use to hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The aforementioned planned travel route is the route from point 1 to point 2. The process of selecting the next destination base station to be the next source base station, and selecting the next destination base station to hand over from the next source base station, is repeatedly performed from the source base station, which includes the first point in the communication area, until the destination base station, which includes the second point in the communication area, is selected. The base station selection unit selects the destination base station such that the total number of destination base stations selected from the first point to the second point is less than or equal to a threshold, and the travel time between the handover area of ​​the source base station and the destination base station is equal to or greater than the handover time. Handover system (S).

15. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, A route acquisition unit (101, 351) acquires the planned future movement path of the aforementioned moving object, Area information extraction unit (105, 355) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route from the communication information storage unit (103, 353) which stores area information indicating the communication area in which the base station can communicate, A travel time prediction unit (106, 356) predicts the travel time required for the mobile body to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. A communication status acquisition unit (102, 352) acquires handover performance information indicating the handover time required for a communication device other than the aforementioned communication device to hand over from the source base station to the other candidate base station, Based on the aforementioned travel time, a base station selection unit (153, 201) selects from among the other candidate base stations the communication device will use to hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, If the travel time within the handover area between the source base station and the destination base station is shorter than the handover time, a speed determination unit (155) determines the speed at which the moving object travels along the planned travel path included in the handover area so that the travel time becomes equal to or greater than the handover time. A speed indicator unit (156) outputs speed information indicating the determined speed, A handover system (S) equipped with the following.

16. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, A route acquisition unit (101, 351) acquires the planned future movement path of the aforementioned moving object, A communication status acquisition unit (102, 352) that receives communication status information indicating the communication status of the base station, Area information extraction unit (105, 355) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route from the communication information storage unit (103, 353) which stores area information indicating the communication area in which the base station can communicate, A travel time prediction unit (106, 356) predicts the travel time required for the mobile body to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. Based on the aforementioned travel time, a base station selection unit (153, 201) selects from among the other candidate base stations the communication device will use to hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, If the communication status information indicates that a specific base station is unable to communicate, the area information extraction unit extracts the area information of the candidate base stations excluding the specific base station. Handover system (S).

17. A handover system that performs a handover of a communication device mounted on a mobile device to a base station to which it is connected, The handover system comprises a handover information providing device (100) provided on the outside of the mobile body and a handover device (150) mounted on the mobile body. The aforementioned handover information providing device is A route acquisition unit (101) acquires the planned future movement path of the aforementioned moving object, From the communication information storage unit (103) which stores area information indicating the communication area in which the base station can communicate, an area information extraction unit (105) extracts the area information of candidate base stations that the communication device can connect to along the planned travel route, A travel time prediction unit (106) predicts the travel time required for the moving object to travel along the planned travel route, which is included in a handover area where the communication area of ​​one candidate base station (the source base station) and the communication area of ​​another candidate base station overlap among the communication areas indicated by the extracted area information, and where a handover from the source base station to the other candidate base station is possible. The system includes a handover information transmission unit (107) that transmits handover information to the communication device, which includes travel time information indicating the travel time and base station information indicating the candidate base station. The aforementioned handover device is A handover information receiving unit (151) that receives the aforementioned handover information, Based on the aforementioned travel time, a base station selection unit (153) selects a destination base station from among the other candidate base stations to which the communication device will hand over from the source base station, When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, A handover system (S) equipped with the following.

18. A handover device (150, 350) that performs a handover to a base station to which a communication device mounted on a mobile device is connected, A base station information acquisition unit (151, 355) acquires base station information indicating candidate base stations that can be connected to along the future planned route of the mobile body, A travel time information acquisition unit (151, 356) acquires travel time information indicating the estimated travel time required for the moving object to travel along the planned travel route, which is included in the handover area where the connecting base station, which is one of the candidate base stations, can communicate and where the communication area where the other candidate base stations can communicate overlaps, and where handover from the connecting base station to the other candidate base station is possible. A base station selection unit (153) selects a destination base station from among the other candidate base stations based on the travel time indicated by the travel time information, to which the communication device will hand over from the source base station. When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The destination base station is the candidate base station with the longest travel time among the other candidate base stations. Handover device.

19. A handover device (150, 350) that performs a handover to a base station to which a communication device mounted on a mobile device is connected, A base station information acquisition unit (151, 355) acquires base station information indicating candidate base stations that can be connected to along the future planned route of the mobile body, A travel time information acquisition unit (151, 356) acquires travel time information indicating the estimated travel time required for the moving object to travel along the planned travel route, which is included in the handover area where the connecting base station, which is one of the candidate base stations, can communicate and where the communication area where the other candidate base stations can communicate overlaps, and where handover from the connecting base station to the other candidate base station is possible. A base station selection unit (153) selects a destination base station from among the other candidate base stations based on the travel time indicated by the travel time information, to which the communication device will hand over from the source base station. When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The communication device and the source base station and the destination base stations, namely the first and second destination base stations, can communicate using the first and second communication lines, which use the same communication method. The first destination base station is the candidate base station with the longest travel time among the other candidate base stations, and the second destination base station is the candidate base station with the second longest travel time among the other candidate base stations. The base station switching unit performs a handover from the source base station to the first destination base station using the first communication line, and a handover from the source base station to the second destination base station using the second communication line. Handover device.

20. A handover device (150, 350) that performs a handover to a base station to which a communication device mounted on a mobile device is connected, A base station information acquisition unit (151, 355) acquires base station information indicating candidate base stations that can be connected to along the future planned route of the mobile body, A travel time information acquisition unit (151, 356) acquires travel time information indicating the estimated travel time required for the moving object to travel along the planned travel route, which is included in the handover area where the connecting base station, which is one of the candidate base stations, can communicate and where the communication area where the other candidate base stations can communicate overlaps, and where handover from the connecting base station to the other candidate base station is possible. A communication status acquisition unit (151, 352) acquires handover performance information indicating the handover time required for a communication device other than the aforementioned communication device to hand over from the source base station to the other candidate base station, A base station selection unit (153) selects a destination base station from among the other candidate base stations based on the travel time indicated by the travel time information, to which the communication device will hand over from the source base station. When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, The aforementioned planned travel route is the route from point 1 to point 2. The process of selecting the next destination base station to be the next source base station, and selecting the next destination base station to hand over from the next source base station, is repeatedly performed from the source base station, which includes the first point in the communication area, until the destination base station, which includes the second point in the communication area, is selected. The base station selection unit selects the destination base station such that the total number of destination base stations selected from the first point to the second point is less than or equal to a threshold, and the travel time between the handover area of ​​the source base station and the destination base station is equal to or greater than the handover time. Handover device.

21. A handover device (150, 350) that performs a handover to a base station to which a communication device mounted on a mobile device is connected, A base station information acquisition unit (151, 355) acquires base station information indicating candidate base stations that can be connected to along the future planned route of the mobile body, A travel time information acquisition unit (151, 356) acquires travel time information indicating the estimated travel time required for the moving object to travel along the planned travel route, which is included in the handover area where the connecting base station, which is one of the candidate base stations, can communicate and where the communication area where the other candidate base stations can communicate overlaps, and where handover from the connecting base station to the other candidate base station is possible. A communication status acquisition unit (151, 352) acquires handover performance information indicating the handover time required for a handover from the source base station to the destination base station by a communication device other than the aforementioned communication device, A base station selection unit (153) selects a destination base station from among the other candidate base stations based on the travel time indicated by the travel time information, to which the communication device will hand over from the source base station. When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, If the travel time within the handover area between the source base station and the destination base station is shorter than the handover time, a speed determination unit (155) determines the speed at which the moving object travels along the planned travel path included in the handover area so that the travel time becomes equal to or greater than the handover time. A speed indicator unit (156) outputs speed information indicating the determined speed, A handover device equipped with [the following features].

22. A handover device (350) that performs a handover to a base station to which a communication device mounted on a mobile device is connected, A communication status acquisition unit (352) acquires communication status information indicating the communication status of the base station, A base station information acquisition unit (355) acquires base station information indicating candidate base stations that can be connected to along the future planned route of the mobile body, A travel time information acquisition unit (356) acquires travel time information indicating the estimated travel time required for the moving object to travel along the planned travel route, which is included in the handover area where the connecting base station, which is one of the candidate base stations, can communicate and where the communication area where the other candidate base stations can communicate overlaps, and where handover from the connecting base station to the other candidate base station is possible. A base station selection unit (153) selects a destination base station from among the other candidate base stations based on the travel time indicated by the travel time information, to which the communication device will hand over from the source base station. When the mobile body moves to the handover area, the base station switching unit (154) switches the base station to which the communication device is connected from the source base station to the destination base station, Equipped with, If the communication status information indicates that a specific base station is unable to communicate, the base station information acquisition unit acquires base station information indicating candidate base stations excluding the specific base station. Handover device.

Images