Information processing method, program, and information processing device

Abstract

According to the present invention, in a communication system in which a moving user device communicates with a plurality of access points, a first access point included in the plurality of access points acquires situation data for reporting a situation of a wireless communication environment from another access point included in the communication system, acquires a connection plan to an access point during movement from the user device, and notifies the user device of information pertaining to connection based on the situation data and the connection plan.

Description

Information Processing Method, Program, and Information Processing Apparatus

[0001] This disclosure relates to wireless communication.

[0002] In a wireless LAN environment, there is a technology for roaming a user terminal between multiple access points (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-177768

[0004] IEEE 802.11r, [online], IEEE 802, [searched on February 6, 2025], Internet <URL: https: / / grouper.ieee.org / groups / 802 / 11 / Reports / tgr_update.htm>

[0005] An object of this disclosure is to improve communication performance in a wireless communication system including a plurality of access points.

[0006] One aspect of this disclosure is an information processing method executed by a first access point included in a plurality of access points in a communication system in which a moving user device communicates with the plurality of access points, the method including: obtaining status data reporting the status of a wireless communication environment from other access points included in the communication system; obtaining a connection plan to an access point during movement from the user device; and notifying the user device of connection-related information based on the status data and the connection plan.

[0007] One aspect of this disclosure is an information processing method executed by a user device in a communication system in which a moving user device communicates with a plurality of access points, the method including: transmitting a connection plan to an access point during movement of the own device to a first access point included in the plurality of access points; receiving connection-related information based on the connection plan from the first access point; and changing an access point that the own device is scheduled to connect to during movement or a wireless channel to be used at each access point based on the connection-related information.

[0008] One aspect of the present disclosure is an information processing device that functions as a first access point in a communication system in which a mobile user device communicates with a plurality of access points, and has a control unit that performs the following: acquiring status data reporting the status of the wireless communication environment from other access points included in the communication system; acquiring a connection plan to the access point while in motion from the user device; and notifying the user device of connection information based on the status data and the connection plan.

[0009] One aspect of the present disclosure is an information processing device that functions as a user device in a communication system in which a mobile user device communicates with a plurality of access points, and includes a control unit that performs the following actions: transmits a connection plan to the access points during the movement of the device to a first access point included in the plurality of access points; receives connection information from the first access point based on the connection plan; and changes the access point to which the device is scheduled to connect during the movement, or the radio channel to be used at each access point, based on the connection information.

[0010] Other embodiments include a program for causing a computer to execute the above method, or a computer-readable storage medium that non-temporarily stores the program.

[0011] According to this disclosure, communication performance can be improved in a wireless communication system that includes multiple access points.

[0012] A schematic diagram of the communication system according to the first embodiment. A diagram showing the positional relationship between the vehicle's route and the roadside equipment. Hardware configuration diagram of the in-vehicle device according to the first embodiment. Hardware configuration diagram of the roadside equipment according to the first embodiment. Software configuration diagram of the in-vehicle device according to the first embodiment. An example of access point information held by the in-vehicle device. An example of a roaming plan generated by the in-vehicle device. Software configuration diagram of the roadside equipment according to the first embodiment. An example of status data and status master data generated and managed by the roadside equipment. A flowchart of the processing performed by the in-vehicle device. A flowchart of the processing performed by the roadside equipment. A sequence diagram showing the data flow during handshake. A flowchart showing the processing of step S33 in detail. A sequence diagram showing the data flow during roaming. A sequence diagram showing the data flow during roaming.

[0013] In wireless LAN environments such as Wi-Fi (registered trademark), there are systems that enable the handover of user terminals between multiple access points (hereinafter referred to as roaming). In such systems, for example, the authentication results of the user terminal are shared among multiple access points. This makes it possible to reconnect quickly by skipping the authentication phase, even if the user terminal moves and the destination access point changes.

[0014] Furthermore, there are efforts to apply Wi-Fi communication methods to high-speed moving vehicles. For example, by placing multiple access points along main roads and enabling roaming, low-cost mobile communication can be achieved.

[0015] Furthermore, by pre-determining the access points that a mobile device (such as a vehicle) intends to connect to while in motion, the phase of detecting or identifying new access points can be shortened, enabling high-speed roaming.

[0016] On the other hand, the quality of wireless communication via an access point can vary depending on the wireless communication environment of each access point, such as the degree of congestion and interference. However, since mobile devices cannot know the communication environment of each access point (for example, the level of congestion) in advance, it is possible that they may find out after connecting that they cannot obtain sufficient communication speed. The communication method according to this disclosure solves such problems.

[0017] An information processing method according to one aspect of the present disclosure is an information processing method performed by a first access point included in a plurality of access points in a communication system in which a mobile user device communicates with a plurality of access points, and includes: obtaining status data reporting the status of the wireless communication environment from other access points included in the communication system; obtaining a connection plan to the access point while in motion from the user device; and notifying the user device of connection information based on the status data and the connection plan.

[0018] The first access point is one of several access points capable of communicating with a mobile user device. The multiple access points may be, for example, several roadside devices installed at predetermined intervals along a road.

[0019] The first access point obtains status data from other access points included in the communication system, reporting the status of the wireless communication environment. Status data is data used to estimate the quality of wireless communication and typically includes information such as channel availability, channel occupancy, and the number of connected terminals. The first access point also obtains a connection plan from the user device. A connection plan is typically information describing multiple access points that the user device plans to connect to while in transit. The connection plan is generated by the user device. The connection plan may include identifiers of the access points to be connected to, and identifiers of the wireless channels to be connected to at each access point.

[0020] The first access point notifies the user device of connection information based on the status data and the connection plan. The connection information may include the result of evaluating the connection plan based on a plurality of status data. The first access point can evaluate the acquired connection plan based on the connection plan acquired from the user device and status data acquired from a plurality of other access points.

[0021] Evaluating the connection plan may include, for example, determining whether a predetermined wireless communication quality can be obtained when the user device connects to each of the multiple access points described in the connection plan.

[0022] Furthermore, if the first access point determines that the plurality of access points to be connected to include an access point that cannot provide the predetermined wireless communication quality, it may determine an alternative access point that can be connected to while the user device is in motion.

[0023] An alternative access point can be, for example, an access point located in a position where the user device can communicate and which is presumed to have wireless communication quality that meets predetermined requirements. The first access point may notify the user device of information regarding the alternative access point as a result of the evaluation. This allows the first access point to make the user device aware, for example, that the access point to which the user device plans to connect is unsuitable for communication and that an alternative access point is available.

[0024] Furthermore, evaluating the connection plan may include, for example, determining whether a predetermined wireless communication quality can be obtained when the user device connects to each of the multiple access points to be connected to as described in the connection plan, via the wireless channel to be used.

[0025] For example, if the connection plan includes channel information regarding the wireless channels that user devices are expected to use when connecting to each access point, and the status data includes the availability of multiple wireless channels, the first access point can estimate the wireless communication quality with the user devices on a per-wireless channel basis.

[0026] Furthermore, if the first access point determines that the predetermined wireless communication quality cannot be obtained when the user device connects to multiple access points via the wireless channels to be used, it may determine an alternative wireless channel to replace the wireless channel.

[0027] An alternative radio channel is a radio channel used as an alternative at the same access point. For example, if the radio channel specified in the connection plan is already occupied by another terminal, the first access point may suggest to the user device that it use an alternative radio channel. The first access point may also notify the user device of information regarding the alternative radio channel as a result of the evaluation.

[0028] Furthermore, the first access point may generate status data reporting the availability of wireless channels on its own device and transmit the generated status data to each of the other access points. In this way, the first access point may transmit status data from its own device in addition to receiving status data from other access points. In this case, the first access point may transmit status data when the availability of wireless channels on its own device changes.

[0029] The following describes specific embodiments of this disclosure with reference to the drawings. Unless otherwise specified, the hardware configurations, module configurations, functional configurations, etc., described in each embodiment are not intended to limit the technical scope of the disclosure to those configurations alone.

[0030] (First Embodiment) [System Overview] An overview of the communication system according to the first embodiment will be described with reference to Figure 1. The communication system according to this embodiment consists of an on-board device 10 mounted on a vehicle and a plurality of roadside devices 20 installed along the road. The roadside devices 20 are an example of an "access point" in this disclosure. In the example in Figure 1, roadside devices 20A, 20B, and 20C are shown as examples, but when there is no need to distinguish between them, they are collectively referred to as "roadside devices 20".

[0031] The communication system according to this embodiment is a system that performs wireless communication according to the communication procedure specified by IEEE 802.11. Each of the roadside devices 20A, 20B, and 20C has a range (for example, a radius of about 100 meters; shown by the dotted line in Figure 1) that allows data communication with the in-vehicle device 10. The in-vehicle device 10 can connect to any of the roadside devices 20 and communicate while in motion. Furthermore, it can switch the connected roadside device 20 during communication (perform roaming).

[0032] Roaming can be performed by multiple roadside devices 20 sharing information about the in-vehicle device 10. For example, if the connection destination of the in-vehicle device 10 changes from roadside device 20A to roadside device 20B during data communication, roadside device 20B obtains information about the in-vehicle device 10 from roadside device 20A, uses that information to accept the connection from the in-vehicle device 10, and continues communication.

[0033] On the other hand, in wireless LAN systems, when user devices move at high speeds, roaming processing can take time, potentially preventing sufficient communication time from being secured. In recent years, high frequency bands, mainly millimeter waves, are sometimes used to achieve high-speed communication. However, as the frequency band increases, the communication range for each access point narrows, leading to frequent roaming. If the time required for roaming is not reduced, the communication time that can be secured at each access point will decrease.

[0034] To solve this problem, a system is being considered in which the in-vehicle device 10 pre-determines the roadside device 20 to be connected to and performs roaming based on this.

[0035] The explanation will be given with reference to Figure 2. For example, the on-board device 10 has information regarding the geographical location of each roadside device 20 (hereinafter referred to as access point information), and can predetermine which roadside devices 20 to connect to along the route based on the route information of the vehicle itself. Figure 2 is a diagram showing the positional relationship between the route of a vehicle equipped with the on-board device 10 and roadside devices located near that route.

[0036] In the illustrated example, the in-vehicle device 10 can sequentially connect to roadside devices 20 having identifiers R001, R002, R003, and R004 while in motion. Furthermore, the in-vehicle device 10 may predetermine the wireless channel to be used when connecting to each roadside device. In this way, by predetermining the roadside devices to be connected to and the wireless channels, the in-vehicle device 10 can reduce the time required to detect each access point and determine whether or not to connect. In other words, the time required for roaming can be reduced.

[0037] However, this method also has its problems. For example, consider a scenario where, for some reason, one of the roadside devices 20 scheduled for connection cannot provide sufficient communication performance. For instance, in the illustrated example, consider a case where a large number of terminals are connected to the roadside device 20 indicated by the identifier R002, and there are no available wireless channels. In this case, if the in-vehicle device 10 proceeds with the connection according to the predetermined plan, it may not be able to obtain sufficient communication quality during the period it passes through the relevant section.

[0038] To solve this problem, in the communication system according to this embodiment, each of the multiple roadside devices 20 exchanges and shares status data reporting the status of their respective wireless communication environments (for example, the availability of wireless channels). In addition, the in-vehicle device 10 transmits a list of multiple roadside devices 20 to which it plans to connect (hereinafter referred to as the roaming plan) to the roadside devices 20 within its communication range. The roaming plan may include the wireless channels to be used when connecting to each roadside device 20.

[0039] Upon receiving the roaming plan, the roadside device 20 (also referred to as the first access point) refers to pre-shared status data and determines whether "if communication is performed according to the received roaming plan, the wireless communication quality that meets the predetermined requirements can be obtained." In other words, it evaluates the roaming plan. If it is determined that the wireless communication quality that meets the predetermined requirements cannot be obtained, the first access point determines an alternative roadside device 20 or wireless channel and notifies the in-vehicle device 10 of the result.

[0040] In the example shown in Figure 2, for example, roadside device 20 with identifier R001 determines, based on the roaming plan received from the in-vehicle device 10, that "roadside device 20 with identifier R002 cannot provide sufficient communication performance." It then determines that roadside device 20 with identifier R012 can be used as an alternative access point and provides information about the alternative access point to the in-vehicle device 10. Based on this, the in-vehicle device 10 changes the roadside device it is scheduled to connect to. By having each device repeat this operation in real time, it becomes possible to cause the in-vehicle device 10 to communicate in such a way that the wireless communication quality meets predetermined requirements.

[0041] [Hardware Configuration] Next, the hardware configuration of each device that makes up the system will be described. Figure 3 is a schematic diagram showing an example of the hardware configuration of an in-vehicle device 10 that can be mounted on a vehicle.

[0042] The in-vehicle device 10 can be configured as a computer having a processor (CPU, GPU, etc.), a main storage device (RAM, ROM, etc.), and an auxiliary storage device (EPROM, hard disk drive, removable media, etc.). The auxiliary storage device stores an operating system (OS), various programs, various tables, etc. By executing the programs stored therein, various functions (software modules) that meet a predetermined purpose, as described later, can be realized. However, some or all of the functions may be realized as hardware modules by hardware circuits such as ASICs and FPGAs.

[0043] The in-vehicle device 10 includes a control unit 101, a storage unit 102, a communication unit 103, a position information acquisition unit 104, and an input / output unit 105.

[0044] The control unit 101 is an arithmetic unit that realizes various functions of the in-vehicle device 10 by executing a predetermined program. The control unit 101 can be realized by a hardware processor such as a CPU, for example. Also, the control unit 101 may include a RAM, a ROM (Read Only Memory), a cache memory, etc.

[0045] The storage unit 102 is a means for storing information and is composed of a storage medium such as a RAM, a magnetic disk, or a flash memory. The storage unit 102 stores the programs executed by the control unit 101, the data used by the programs, etc.

[0046] The communication unit 103 is a wireless communication interface for transmitting and receiving wireless signals. The communication unit 103 is configured to be able to transmit and receive wireless signals conforming to a standard such as wireless LAN, for example. For example, when the control unit 101 requests a network connection, a wireless connection with the roadside device 20 is established via the communication unit 103.

[0047] The position information acquisition unit 104 acquires the position information of the host vehicle. The position information acquisition unit 104 includes a GPS antenna and a positioning module for positioning the position information. The GPS antenna is an antenna that receives a positioning signal transmitted from a positioning satellite (also referred to as a GNSS satellite). The positioning module is a module that calculates position information based on the signal received by the GPS antenna. Note that the position information acquisition unit 104 may determine the traveling direction of the host vehicle based on the transition of the position information.

[0048] The input / output unit 105 is a unit that receives an input from the vehicle occupants and presents information to the occupants. Specifically, the input / output unit 105 is composed of a touch panel and its control means, and a liquid crystal display and its control means. In this embodiment, the touch panel and the liquid crystal display are composed of a single touch panel display.

[0049] Next, the hardware configuration of the roadside device 20 will be described. FIG. 4 is a diagram schematically showing an example of the hardware configuration of the roadside device 20.

[0050] The roadside device 20 can be configured as a computer having a processor (such as a CPU, GPU, etc.), a main storage device (such as a RAM, ROM, etc.), and an auxiliary storage device (such as an EPROM, a hard disk drive, a removable medium, etc.), similar to the in-vehicle device 10.

[0051] The roadside device 20 includes a control unit 201, a storage unit 202, and a communication unit 203.

[0052] The control unit 201 is an arithmetic unit that realizes various functions of the roadside device 20 by executing a predetermined program. The control unit 201 can be realized by a hardware processor such as a CPU, for example. Further, the control unit 201 may include a RAM, a ROM (Read Only Memory), a cache memory, and the like.

[0053] The memory unit 202 is a means for storing information and is composed of storage media such as RAM, magnetic disks, and flash memory. The memory unit 202 stores programs executed by the control unit 201, data used by those programs, and so on.

[0054] The communication unit 203 is a wireless communication interface for sending and receiving wireless signals to and from the in-vehicle device 10. The communication unit 203 is configured to send and receive wireless signals that conform to standards such as wireless LAN.

[0055] [Software Configuration] Next, the software configuration of each device constituting the system will be described. Figure 5 is a schematic diagram showing the software configuration of the in-vehicle device 10 according to this embodiment. The hardware configuration of the in-vehicle device 10 is as shown in Figure 3.

[0056] In this embodiment, the control unit 101 of the in-vehicle device 10 is configured to include a communication control unit 1011 and a route search unit 1012 as software modules. These software modules may be implemented by the control unit 101 (CPU, etc.) executing programs stored in the storage unit 102. The information processing performed by the software modules is synonymous with the information processing performed by the control unit 101 (CPU, etc.).

[0057] The communication control unit 1011 establishes a connection with one of the multiple roadside devices 20 and performs data transmission and reception (including roaming).

[0058] The communication control unit 1011 detects the presence of a roadside device 20 included in the communication system and requests a connection to the communication system. The communication control unit 1011, for example, receives a beacon frame transmitted from the roadside device 20 and, in response, initiates a connection sequence. The communication control unit 1011 also performs switching of the connection destination (roaming) between other roadside devices 20 as necessary.

[0059] Furthermore, as described above, the communication control unit 1011 has the function of generating a list (roaming plan) of multiple roadside devices 20 (and wireless channels to be used) to which the device is scheduled to connect while in transit, and transmitting the generated roaming plan to the target roadside devices 20 during the handshake. The roaming plan can also be described as a connection plan for multiple roadside devices 20.

[0060] The communication control unit 1011 acquires information about multiple roadside devices 20 available along the route (hereinafter referred to as access point information) and generates a roaming plan based on this access point information. Figure 6 shows an example of access point information. In this embodiment, the access point information includes the identifier, location information, communication standard, frequency band, authentication method, and information about available wireless channels of the roadside device 20. Note that the available wireless channels are based on specifications and are not related to the actual communication situation. In other words, even if a channel is described in the access point information, it may actually already be in use, causing interference.

[0061] Access point information may be pre-stored in the storage unit 102 (access point information 102A in Figure 5). Based on the generated route and access point information, the communication control unit 1011 can pre-determine the roadside devices 20 (and the wireless channels to be used) that will be connected to during driving and generate a roaming plan. The generated roaming plan may be stored in the storage unit 102 (roaming plan 102B in Figure 5). Figure 7 is an example of a roaming plan. The roaming plan describes a plurality of roadside devices 20 that the in-vehicle device 10 is scheduled to connect to, along with the identifier of the roadside device and the identifier of the wireless channel to be used.

[0062] The roadside device 20 receives the roaming plan generated in this manner from the on-board device 10, determines whether its contents are valid, and modifies the roaming plan as necessary. The modified roaming plan is sent back to the on-board device 10. The communication control unit 1011 connects with (and roams with) multiple roadside devices 20 while moving, according to the modified roaming plan.

[0063] The route search unit 1012 performs a route search based on a request from the user. The route search unit 1012 obtains the origin and destination, as well as route search conditions (e.g., whether or not toll roads are used) via the input / output unit 105, and searches for a route connecting the origin and destination. The route may be determined by pairs of nodes and edges in the road network. Information regarding the road network may be obtained from an external device or stored in the storage unit 102. The information obtained as a result of the search is output via the input / output unit 105 and is also used to generate the roaming plan described above.

[0064] Next, the software configuration of the roadside device 20 will be described. Figure 8 is a schematic diagram showing the software configuration of the roadside device 20 according to this embodiment. The hardware configuration of the roadside device 20 is as shown in Figure 4.

[0065] In this embodiment, the control unit 201 of the roadside device 20 is configured to have four software modules: a communication control unit 2011, an authentication unit 2012, a sharing unit 2013, and an evaluation unit 2014. These software modules may be implemented by the control unit 201 (CPU, etc.) executing programs stored in the storage unit 202. The information processing performed by the software modules is synonymous with the information processing performed by the control unit 201 (CPU, etc.).

[0066] The communication control unit 2011 performs data communication with the in-vehicle device 10. Specifically, the communication control unit 2011 performs the following processes.

[0067] (1) The communication control unit 2011 performs a handshake with the in-vehicle device 10 and periodically broadcasts a beacon frame to notify the presence of its own device. When the in-vehicle device 10 responds, the communication control unit 2011 performs a handshake with the in-vehicle device 10, including authentication processing. The authentication processing is performed by the authentication unit 2012, which will be described later. If the authentication result for the target in-vehicle device 10 has already been received from another roadside device 20, the authentication processing is omitted (described later).

[0068] (2) Processing to perform data communication with the in-vehicle device 10 Once the handshake with the in-vehicle device 10 is complete, the communication control unit 2011 starts data communication with the in-vehicle device 10. Data communication may be performed, for example, by repeatedly sending multiple data blocks and receiving block Ack.

[0069] (3) Roaming Processing The communication control unit 2011 also has a function to control roaming between multiple roadside devices 20. For example, the communication control unit 2011 decides to switch the connection destination of the in-vehicle device 10 to another roadside device 20 (roaming) based on the communication status with the in-vehicle device 10. When roaming is performed, the communication control unit 2011 may transmit to the in-vehicle device 10 information about the other roadside device 20 that will be the new connection destination of the in-vehicle device 10. This information includes information about candidate roadside devices 20 that are candidates for connection destination. The in-vehicle device 10 can use this information to switch the connection destination roadside device 20. The communication control unit 2011 also transmits information about the in-vehicle device 10 (such as the identifier of the in-vehicle device 10 and the sequence number in data transmission) to the other roadside devices 20 that are candidates for roaming destination.

[0070] The authentication unit 2012 authenticates the in-vehicle device 10 based on a request from the communication control unit 2011. Authentication can be performed based on authentication information received from the in-vehicle device 10. Authentication information includes, for example, an identifier for uniquely identifying the in-vehicle device 10, a key used when connecting the in-vehicle device 10 to the communication system, or an electronic certificate. The authentication information stored in the in-vehicle device 10 and the authentication information transmitted to the roadside device 20 may be different. For example, if a private key is stored in the in-vehicle device 10, a hash generated based on that private key may be transmitted to the roadside device 20. The authentication unit 2012 may also perform authentication using, for example, PSK (Pre-Shared Key). In this case, the authentication information will be a key generated based on a passphrase. The authentication unit 2012 may also perform, for example, IEEE 802.1x authentication. In this case, the authentication information will be a combination of username and password, or an electronic certificate.

[0071] Furthermore, if the authentication of the in-vehicle device 10 is successful, the authentication unit 2012 transmits the authentication result to other roadside devices 20 belonging to the same communication system. This allows the other roadside devices 20 to continue communication without having to perform authentication again when roaming occurs.

[0072] The shared unit 2013 exchanges and shares data with other roadside devices 20 included in the communication system to report the status of the wireless communication environment. In this embodiment, the status of the wireless communication environment includes the usage status of multiple wireless channels provided by each roadside device 20.

[0073] In this embodiment, the shared unit 2013 generates data representing the usage status of wireless channels in its own device (hereinafter referred to as status data) and transmits it to other roadside devices 20. The status data may include information such as, for example, "According to the standard, 20 channels are available, and 10 of them are currently in use." Figure 9(A) shows an example of status data. The status data includes the identifier of the own device, the location information of the own device, the communication standard, the frequency band, the authentication method, a list of wireless channels available according to the standard, and a list of wireless channels currently in use. The status data may be stored in the storage unit 202 (status data 202A in Figure 8).

[0074] Furthermore, the shared unit 2013 receives status data from other roadside devices 20 and performs the process of registering it in a database (hereinafter referred to as status master data). The status master data is a database that manages the status of the wireless communication environment in multiple roadside devices 20. Figure 9(B) shows an example of status master data. The status master data is updated each time status data is received from other roadside devices 20. The status master data may also be stored in the storage unit 202 (status master data 202B in Figure 8).

[0075] As the shared unit 2013 performs the operations described above, the multiple roadside devices 20 included in the communication system will be able to grasp the availability of each other's wireless channels in real time.

[0076] The status data may be broadcast, but if the communication system has a wide range, adjacent roadside devices 20 may relay the status data to each other so that it is delivered to all roadside devices 20. Alternatively, the status data may be transmitted to other roadside devices 20 via a wired backbone line or server equipment.

[0077] The evaluation unit 2014 acquires a roaming plan from the in-vehicle device 10 and evaluates the validity of the acquired roaming plan based on the status master data managed by its own device.

[0078] In this embodiment, the in-vehicle device 10 transmits a roaming plan to the roadside device 20 at the time of the handshake with the roadside device 20. The evaluation unit 2014 also refers to the status master data to determine whether a predetermined wireless communication quality can be provided when using the roadside device 20 (and wireless channel) included in the received roaming plan. For example, if there are no available wireless channels at the roadside device 20 described in the roaming plan, or if the wireless channel to be used is already occupied, the evaluation unit 2014 determines that the predetermined wireless communication quality cannot be provided at the roadside device 20 in question.

[0079] In such cases, the evaluation unit 2014 either (1) determines a roadside device 20 (also referred to as an "alternative access point") that can provide a predetermined wireless communication quality in place of the roadside device 20 included in the roaming plan, or (2) determines a radio channel (also referred to as an "alternative radio channel") that can provide a predetermined wireless communication quality in place of the radio channel included in the roaming plan.

[0080] The evaluation unit 2014 notifies the in-vehicle device 10 of the determined roadside device 20 or wireless channel. The evaluation unit 2014, for example, executes a process to rewrite the roadside device 20A included in the roaming plan to an alternative roadside device 20B, and transmits the updated roaming plan to the in-vehicle device 10. Alternatively, the evaluation unit 2014, for example, executes a process to rewrite the wireless channel included in the roaming plan to an alternative wireless channel, and transmits the updated roaming plan to the in-vehicle device 10.

[0081] This allows the in-vehicle device 10 to communicate while avoiding roadside devices 20 (or wireless channels) that do not provide sufficient communication performance.

[0082] [Processing Flowchart] Next, we will explain the processing flow in communication. In this example, we will explain assuming that a vehicle equipped with an on-board device 10 is traveling on a road where multiple roadside devices 20 are installed.

[0083] Figure 10 is a flowchart of the process by which the in-vehicle device 10 generates a roaming plan before starting to drive. This process is executed before the vehicle equipped with the in-vehicle device 10 starts driving.

[0084] First, in step S11, the communication control unit 1011 obtains access point information from the storage unit 102. In this example, access point information is obtained from the storage unit 102, but access point information may also be obtained from an external device. For example, if the in-vehicle device 10 has a cellular communication module, the communication control unit 1011 may obtain access point information from an external device via cellular communication.

[0085] Next, in step S12, the route search unit 1012 obtains the route of the vehicle connecting the departure point and the destination. Information regarding the destination and intermediate points may be obtained from the vehicle's occupants via the input / output unit 105.

[0086] In step S13, the communication control unit 1011 generates a roaming plan based on the obtained route and access point information. For example, the communication control unit 1011 identifies roadside devices 20 that can communicate during travel based on the geographical locations of the multiple roadside devices 20 described in the access point information, and designates them as roadside devices 20 to be connected to. It also determines the wireless channel to be used when connecting to each roadside device 20. This generates a roaming plan as shown in Figure 7.

[0087] Figure 11 is a flowchart of the process by which roadside devices 20 exchange status data with other roadside devices 20. This process is performed periodically by each of the multiple roadside devices 20.

[0088] First, in step S21, the shared unit 2013 generates data (status data) representing the usage status of wireless channels in its own device and transmits it to other roadside devices 20. As described above, the status data includes the roadside device identifier, location information, communication standard, frequency band, authentication method, a list of wireless channels available according to the standard, and a list of wireless channels currently in use.

[0089] Next, in step S22, the shared unit 2013 receives status data from other roadside devices 20 and registers it in the status master data 202B. If a record corresponding to the same roadside device 20 already exists, the contents of that record are updated. By having multiple roadside devices 20 repeatedly perform the process shown in Figure 11, the roadside devices 20 included in the communication system can grasp the availability of wireless channels of other roadside devices 20 in real time.

[0090] In the explanation of Figure 11, steps S21 and S22 are shown together for convenience, but the two steps do not necessarily have to be executed together. Also, the execution order of each step does not have to be as shown in the figure. Furthermore, the processing of step S21 may be triggered by a change in the availability of the wireless channel of the device. In other words, if there is no change in the availability of the wireless channel of the device, the execution of step S21 may be skipped.

[0091] Next, we will specifically describe the processes performed by each device while the vehicle equipped with the on-board device 10 is in motion. Figure 12 is a sequence diagram of data transmitted and received between the on-board device 10 and a roadside device 20 when the on-board device 10 connects to a roadside device 20 included in the roaming plan. In this example, the access point to which the on-board device 10 first connects is designated as roadside device 20A, and the access point to which the on-board device 10 next connects (i.e., the roaming destination) is designated as roadside device 20B.

[0092] The roadside device 20A periodically transmits beacon frames. A beacon frame is data broadcast by the roadside device 20 to announce the presence of the device. When the in-vehicle device 10 receives a beacon frame from the roadside device 20A, the in-vehicle device 10 initiates the procedure to connect to the roadside device 20A.

[0093] The beacon frame contains the identifier of the roadside device 20A, and the in-vehicle device 10 sends a probe request to the roadside device 20A containing the identifier of the roadside device 20A with which it wishes to connect. If beacon frames are received from multiple roadside devices 20, the in-vehicle device 10 may select a connection destination according to the roaming plan. For example, the in-vehicle device 10 may ignore beacon frames received from roadside devices 20 that are not described in the roaming plan. In this example, the in-vehicle device 10 selects roadside device 20A as the connection destination and sends a probe request to roadside device 20A. In this example, the roadside device 20 sends a beacon frame as an example, but the connection sequence may also be initiated by the in-vehicle device 10 sending a probe request without using a beacon frame.

[0094] When the roadside device 20A receives a probe request addressed to itself, the roadside device 20A sends a probe response containing its network information, etc., to the in-vehicle device 10. Upon receiving the probe response, the in-vehicle device 10 sends an authentication request to the roadside device 20A requesting authentication. The authentication request may include authentication information (such as key information) held by the in-vehicle device 10.

[0095] When the roadside device 20A receives an authentication request, it performs a step (step S31) to authenticate the in-vehicle device 10. In step S31, the roadside device 20A (authentication unit 2012) authenticates the in-vehicle device 10 based on the authentication information received from the in-vehicle device 10. Authentication may be performed, for example, by PSK (Pre-Shared Key) or IEEE 802.1x authentication.

[0096] Once the authentication of the in-vehicle device 10 is complete, the roadside device 20A performs a process to share the authentication result with other roadside devices 20 included in the communication system (step S32). For example, the roadside device 20A (authentication unit 2012) transmits the authentication result performed in step S31 to a roadside device 20B belonging to the same communication system (or the same group) (for example, a roadside device 20B having the same group address as roadside device 20A). This eliminates the need for each roadside device 20 to individually authenticate the in-vehicle device 10.

[0097] If the authentication unit 2012 has already received the authentication result from another roadside device 20 for the target in-vehicle device 10, steps S31 and S32 are skipped.

[0098] Once the authentication process is complete, the roadside device 20A sends a notification (authentication completion notification) to the in-vehicle device 10 indicating that the authentication has been completed.

[0099] Once authentication is complete, the in-vehicle device 10 sends an association request (connection request) to the roadside device 20A. In this embodiment, the in-vehicle device 10 (communication control unit 1011) sends the roaming plan it has to the roadside device 20A (communication control unit 2011) at the same time as the association request.

[0100] In step S33, the roadside device 20A (communication control unit 2011) processes the association request, and the evaluation unit 2014 evaluates the roaming plan received from the in-vehicle device 10.

[0101] Figure 13 is a flowchart of the process performed by the evaluation unit 2014 in step S33.

[0102] First, in step S331, the evaluation unit 2014 determines whether a predetermined wireless communication quality can be obtained at all roadside devices when communication is performed using the combination of roadside devices 20 and wireless channels described in the roaming plan. The evaluation unit 2014 may determine, for example, that sufficient wireless communication quality cannot be obtained because the number of terminals connected to the target roadside device 20 exceeds a threshold, or because the target wireless channel is occupied by other terminals. The determination criteria, such as the threshold number of connected terminals, may be stored in advance in the storage unit 202.

[0103] If, in step S331, it is determined that a predetermined wireless communication quality cannot be obtained at any of the roadside devices described in the roaming plan, the process proceeds to step S332.

[0104] In step S332, the evaluation unit 2014 determines an alternative roadside device 20 or wireless channel and updates the roaming plan. In this step, the roadside device included in the roaming plan is rewritten to an alternative roadside device, or the wireless channel included in the roaming plan is rewritten to an alternative wireless channel, so that a predetermined wireless communication quality can be obtained. If a roadside device is replaced, the alternative roadside device is one that is located in a position where the in-vehicle device 10 can communicate and that is determined to provide a predetermined wireless communication quality based on the status master data. If a wireless channel is replaced, the alternative wireless channel is one that is determined to provide a predetermined wireless communication quality based on the status master data.

[0105] Returning to Figure 12, let's continue the explanation. Once step S33 is complete, an association response is sent from the roadside device 20A to the in-vehicle device 10. At this time, the updated roaming plan is also sent from the roadside device 20A to the in-vehicle device 10. If the roaming plan has not been updated, the roadside device 20A may notify the in-vehicle device 10 that there is no update. Alternatively, if the roaming plan has not been updated, the roadside device 20A may send the original roaming plan to the in-vehicle device 10. The handshake between the in-vehicle device 10 and the communication system is completed through the process described above.

[0106] Once the handshake between the in-vehicle device 10 and the communication system is complete, data communication begins. Data communication may, for example, involve the in-vehicle device 10 transmitting data collected in the vehicle to the roadside device 20A. Data communication may also be performed by repeatedly transmitting multiple data blocks and receiving block Ack.

[0107] Figure 14 is a sequence diagram of data transmitted and received between the in-vehicle device 10 and the roadside device 20 when roaming is performed. The illustrated process begins when the roadside device 20A decides to roam the communication from the in-vehicle device 10 to another roadside device 20B. Whether or not roaming is performed can be determined based on, for example, the location information of the in-vehicle device 10, the radio wave field strength, the communication error rate, etc.

[0108] First, in step S41, the communication control unit 2011 determines the next roadside device 20 to which the in-vehicle device 10 will connect (i.e., the roaming destination) based on the roaming plan. The roaming destination can be determined based on the roaming plan previously received from the in-vehicle device 10.

[0109] Once the roaming destination roadside device is determined, the communication control unit 2011 of roadside device 20A transmits information regarding the target in-vehicle device 10 to the communication control unit 2011 of roadside device 20B. This information may include the identifier of the in-vehicle device 10, its movement status, and the status of data transmission and reception (sequence number). The communication control unit 2011 of roadside device 20A also notifies the in-vehicle device 10 that roaming has occurred.

[0110] The in-vehicle device 10 determines the next roadside device 20B to connect to based on the roaming plan stored in the device (step S42), and initiates a connection with the roadside device 20B by sending a probe request to that roadside device 20B. The series of connection procedures are as described with reference to Figure 12. If the authentication result of the in-vehicle device 10 has been shared in advance, the authentication process is omitted and communication starts immediately.

[0111] In Figure 14, an example is shown where the roadside device 20A initiates roaming, but roaming may also be initiated by the on-board device 10. Figure 15 is a sequence diagram when roaming is initiated by the on-board device 10. In this case, after the on-board device 10 executes step S42, it sends a roaming request to the roadside device 20A, and then the roadside device 20A executes step S41. Once the roadside device 20A has completed information exchange with the roadside device 20B, it sends a roaming response to the on-board device 10. It is also possible to perform roaming in this manner.

[0112] As described above, the roadside device 20 according to the first embodiment generates status data that reports the status of its wireless communication environment and shares this data among multiple roadside devices. The in-vehicle device 10 also generates a roaming plan in advance, which includes a list of roadside devices 20 to connect to while moving, and transmits this plan to the roadside devices 20 during the handshake.

[0113] The roadside device 20 determines whether a predetermined wireless communication quality can be obtained at the multiple roadside devices 20 described in the roaming plan received from the in-vehicle device 10. If the predetermined wireless communication quality cannot be obtained, it determines an alternative roadside device or wireless channel and notifies the in-vehicle device 10 of this. With this configuration, in a configuration in which the in-vehicle device 10 connects to multiple access points using a pre-generated roaming plan, it becomes possible to update the roaming plan as needed to match the real-time wireless communication environment.

[0114] (Modifications) The embodiments described above are merely examples, and this disclosure may be modified as appropriate without departing from its essence. For example, the processes and means described in this disclosure can be freely combined and implemented as long as no technical inconsistencies arise.

[0115] Furthermore, while the first embodiment described an example in which the updated roaming plan is transmitted from the roadside device 20 to the in-vehicle device 10, the embodiment is not limited to this form as long as the evaluation results of the roaming plan by the roadside device 20 can be notified to the in-vehicle device 10. For example, the roadside device 20 may independently transmit information about alternative access points or information about alternative wireless channels to the in-vehicle device 10.

[0116] Furthermore, in the first embodiment, data representing the usage status of the wireless channel in the roadside device 20 was given as an example of status data, but other information may be included in the status data as long as it is possible to estimate the quality of wireless communication. For example, a numerical value representing the number of terminals currently connected to the device may be included in the status data.

[0117] Furthermore, in this embodiment, each roadside device 20 performs authentication of the in-vehicle device 10, but the authentication of the in-vehicle device 10 may be performed by an external authentication server. In this case, the authentication server and each roadside device 20 may communicate wirelessly or via a wired connection. Even in this case, the authentication result of the in-vehicle device 10 is shared among all roadside devices 20 included in the communication system.

[0118] Furthermore, a process described as being performed by a single device may be divided and executed by multiple devices. Conversely, a process described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration (server configuration) by which each function is implemented can be flexibly changed.

[0119] The present disclosure can also be realized by supplying a computer program implementing the functions described in the embodiments above to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer by a non-temporary computer-readable storage medium that can be connected to the computer's system bus, or it may be provided to the computer via a network. Non-temporary computer-readable storage mediums include, for example, any type of disk such as magnetic disks (floppy disks, hard disk drives (HDDs), etc.), optical disks (CD-ROMs, DVDs, Blu-ray discs, etc.), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, optical cards, and any type of medium suitable for storing electronic instructions.

[0120] 10...In-vehicle device 20...Roadside device 101, 201...Control unit 102, 202...Storage unit 103, 203...Communication unit 104...Location information acquisition unit 105...Input / output unit

Claims

1. An information processing method performed by a first access point included in a plurality of access points in a communication system in which a mobile user device communicates with a plurality of access points, the method comprising: acquiring status data reporting the status of the wireless communication environment from other access points included in the communication system; acquiring a connection plan to the access point while in motion from the user device; and notifying the user device of connection information based on the status data and the connection plan.

2. The information processing method according to claim 1, wherein the information relating to the connection includes the result of evaluating the connection plan based on a plurality of status data, and the evaluation of the connection plan includes determining whether a predetermined wireless communication quality can be obtained when the user device connects to each of the plurality of access points that are scheduled to be connected as described in the connection plan.

3. The information processing method according to claim 2, which, when it is determined that the plurality of access points to be connected to include an access point that cannot provide the predetermined wireless communication quality, determines an alternative access point that can be replaced by the access point and that the user device can connect to while in transit.

4. The information processing method according to claim 3, wherein information regarding the alternative access point is notified to the user device as a result of the evaluation.

5. The information processing method according to claim 1, wherein the connection plan includes channel information relating to the wireless channels that the user device is scheduled to use when connecting to each access point, and the status data includes the availability status of a plurality of wireless channels.

6. The information processing method according to claim 5, wherein evaluating the connection plan includes determining whether a predetermined wireless communication quality can be obtained when the user device connects to each of the multiple access points to be connected as described in the connection plan via the wireless channel to be used.

7. The information processing method according to claim 6, which determines an alternative wireless channel to replace the wireless channel when the user device connects to the plurality of access points to be connected via the wireless channel to be used and it is determined that the predetermined wireless communication quality cannot be obtained.

8. The information processing method according to claim 7, wherein information relating to the alternative wireless channel is notified to the user device as a result of the evaluation.

9. The information processing method according to claim 1, further comprising generating status data that reports the availability of wireless channels in the device itself, and transmitting the generated status data to each of the other access points.

10. The information processing method according to claim 9, wherein the first access point transmits the status data when the availability of its wireless channel changes.

11. Information processing method to be performed by a user device in a communication system in which a mobile user device communicates with a plurality of access points, the method comprising: transmitting a connection plan to the access points during the movement of the device to a first access point included in the plurality of access points; receiving connection information from the first access point based on the connection plan; and changing the access points that the device plans to connect to during the movement, or the wireless channels that it plans to use at each access point, based on the connection information.

12. The information processing method according to claim 11, wherein the information relating to the connection includes an instruction to change at least one of the multiple access points scheduled to be connected, as described in the connection plan, to an alternative access point.

13. The information processing method according to claim 11, wherein the connection plan includes channel information relating to the wireless channels that the user device is scheduled to use when connecting to each access point.

14. The information processing method according to claim 13, wherein the information relating to the connection includes an instruction to change the radio channel used at at least one of the multiple access points to be connected, as described in the connection plan.

15. A program for causing a computer to execute the information processing method described in any one of claims 1 to 14.

16. Information processing device that functions as a first access point in a communication system in which a mobile user device communicates with multiple access points, the information processing device having a control unit that performs the following: acquiring status data reporting the status of the wireless communication environment from other access points included in the communication system; acquiring a connection plan to the access point while in motion from the user device; and notifying the user device of connection information based on the status data and the connection plan.

17. Information processing device that functions as a user device in a communication system in which a mobile user device communicates with multiple access points, the information processing device having a control unit that performs the following: transmitting a connection plan to the access points during the movement of the device to a first access point included in the multiple access points; receiving connection information from the first access point based on the connection plan; and changing the access point to which the device is scheduled to connect during the movement, or the wireless channel to be used at each access point, based on the connection information.

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