Communication system, broadcasting device, communication method and program

Abstract

The present invention reduces the information management burden for achieving flexible broadcast. A broadcast communication device according to the present invention has a broadcast destination specifying unit and a broadcast transmission unit. The broadcast destination specifying unit is configured to specify terminals that are located in a specific geographical area on the basis of location information for the terminals. The broadcast transmission unit is configured to transmit a broadcast packet that includes filter information for identifying the terminals that are located in the specific geographical area to destination first multicast addresses that, of respective first multicast addresses for a plurality of partial areas into which a given geographical area is partitioned, correspond to the partial areas that at least partially overlap the specific geographical area. A relay device that corresponds to the destination first multicast addresses has a forwarding unit that is configured to forward the broadcast packet to the specified terminals among the terminals accommodated by the relay device on the basis of the filter information included in the broadcast packet.

Description

[Technical Field]

[0001] The present invention relates to a communication system, a broadcasting device, a communication method, and a program. [Background technology]

[0002] When an event such as an accident, traffic jam, or falling object occurs, it may be necessary to simultaneously transmit information such as danger information to vehicles and information terminals within a certain range from the point of occurrence. In such cases, it is necessary to flexibly specify the range of destinations depending on the type and scale of the event that has occurred, and to simultaneously transmit information to many destinations.

[0003] Geographic Multicast has been proposed as a technology for broadcasting location information, in which location coordinates are divided into a hierarchical grid, a bit string corresponding to each grid coordinate is assigned, and this value is embedded in an IPv6 multicast address. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Kazuya Okada, Tsuyoshi Okuda, Hide Yamaguchi, "GALMA: Design of Geographically Aggregatable Location-Dependent Multicast Addresses," IPSJ Technical Report, 2012-EIP-57, 25, pp.1-8, 2012 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with this conventional technology, if you want to specify destinations flexibly, you need to divide the grid into smaller sections and create multicast groups, which creates the problem that as the grid size becomes smaller, the amount of management information such as multicast addresses, routing settings, and members of each group increases exponentially.

[0006] The present invention has been made in view of the above points, and has as its object to reduce the burden of information management for realizing flexible broadcasting. [Means for solving the problem]

[0007] In order to solve the above problem, in a communication system including a broadcasting device that transmits packets and a plurality of relay devices that accommodate terminals that are candidate destinations for the packets, the broadcasting device has a broadcast destination identification unit configured to identify the terminals located in a specific geographical range based on location information of the terminals, and a broadcast sending unit configured to transmit a broadcast packet addressed to a first multicast address corresponding to a divided range that at least partially overlaps the specific geographical range, out of first multicast addresses for each divided range that divides a certain geographical range into multiple ranges, and including filter information for identifying the terminals located in the specific geographical range, and the relay device corresponding to the first multicast address that is the destination has a forwarding unit configured to forward the broadcast packet to the terminals accommodated by the relay device that are identified based on the filter information included in the broadcast packet. [Effects of the Invention]

[0008] The load of information management required to realize flexible broadcasting can be reduced. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a configuration of a communication system 1 according to an embodiment of the present invention. [Figure 2] 1 is a diagram illustrating an example of a hardware configuration of a broadcasting device 10 according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a location information managing device 30. [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of a network information management device 40. [Figure 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal 60. [Figure 6] 2 is a diagram illustrating an example of a functional configuration of a broadcasting device 10. FIG. [Figure 7] FIG. 2 is a diagram illustrating an example of a functional configuration of a relay device 50. [Figure 8] 10 is a sequence diagram illustrating an example of a processing procedure for issuing a terminal ID and updating a location information management DB 33. FIG. [Figure 9] FIG. 10 is a diagram illustrating an example of the configuration of a terminal ID. [Figure 10] FIG. 10 is a diagram showing an example of the configuration of a forwarding table 54. [Figure 11] FIG. 2 is a diagram illustrating an example of the configuration of a location information management DB 33. [Figure 12] FIG. 10 is a sequence diagram illustrating an example of a processing procedure for transmitting a broadcast packet. [Figure 13] FIG. 10 is a diagram illustrating an example of the configuration of a NW information management DB 43. [Figure 14] FIG. 10 is a diagram illustrating an example of an encapsulated broadcast packet. [Figure 15] FIG. 10 is a sequence diagram illustrating an example of a processing procedure for forwarding a broadcast packet. [Figure 16] FIG. 10 is a diagram showing an example of broadcast transmission realized in the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a communication system 1 according to an embodiment of the present invention. In Fig. 1, the communication system 1 includes a message generation device 20, a broadcasting device 10, a location information management device 30, a network information management device 40, a plurality of relay devices 50, and a plurality of terminals 60.

[0011] The message generating device 20 is a computer that, for example, when some kind of event occurs, generates a message (hereinafter referred to as a "notification message") for terminals 60 located in a specific geographical area (hereinafter referred to as a "notification destination area") that is the destination of notification of the event. The message generating device 20 can communicate with the broadcasting device 10 via a network, and transmits a request (hereinafter referred to as a "broadcast request") to the broadcasting device 10 to broadcast the notification message to the notification destination area. The broadcast request includes the notification destination area and the notification message.

[0012] The broadcasting device 10 is one or more computers that multicast a broadcast packet related to a notification message to terminals 60 located in the notification destination area in response to a broadcast request from the message generating device 20. At this time, the broadcasting device 10 inquires of the location information managing device 30 about the terminals 60 located in the notification destination area. In order to perform LISP-based transfer to improve scalability in the network N1, which is the core network, the broadcasting device 10 also obtains information about the relay device 50 corresponding to the notification destination area from the network information managing device 40, encapsulates the broadcast packet, and transmits it.

[0013] The location information management device 30 is one or more computers that manage the location information of each terminal, a multicast address corresponding to the location, and identification information of each terminal. The location-based multicast address is a multicast IP address assigned to each divided range that divides the range in which the communication system 1 (broadcasting device 10) can communicate. In this embodiment, an EID (Endpoint ID) in LISP (Locator Identity Separation Protocol) is used as the multicast address. Basically, the divided range is fixed. Therefore, the EID corresponding to a certain divided range is fixed.

[0014] The network information management device 40 is one or more computers that respond to an inquiry from the broadcasting device 10 with information on the encapsulation header required for transfer to the network N1.

[0015] The relay device 50 is a network device that functions as, for example, a PE router (Provider Edge router). The relay device 50 replicates packets addressed to the destination terminals 60 using destination address information included in the broadcast packet and filter information included in the broadcast packet to identify the destination terminals 60. The location of each relay device 50 is fixed. Therefore, the segmented ranges that each relay device 50 corresponds to are fixed. The correspondence between the relay device 50 and the segmented ranges may be one-to-one, one-to-many, many-to-one, or many-to-many. The correspondence may be different for each relay device 50. It is possible that multiple carriers cover the same segmented range. Therefore, different relay devices 50, i.e., terminals 60 accommodated by different carriers, may correspond to the same EID. The relay device 50 is associated with a LISP RLOC (Routing Locator) in the network N1. In this embodiment, the RLOC is a multicast address assigned to the relay device 50 that accommodates the EID.

[0016] RLOCs are assigned to groups of EIDs (associated with one or more EIDs) to improve scalability on the core network side of network N1. For example, if there are 1,000 EIDs to be broadcast, instead of broadcasting all 1,000 routes corresponding to the EIDs to network N1, by assigning an RLOC to each group of 10 EIDs, such as RLOC1 for the group of EIDs 0 to 9 and RLOC2 for the group of EIDs 10 to 19, it becomes possible to broadcast 100 routes corresponding to the RLOCs to network N1. The same RLOC is assigned to multiple relay devices 50 that accommodate the same EID, but multiple different RLOCs do not correspond to the same EID.

[0017] Terminal 60 is a communication device that is a candidate destination of a notification message. Terminal 60 joins a multicast group corresponding to the division range in which it is located, and when relay device 50 that accommodates terminal 60 receives a broadcast packet addressed to that multicast group, it receives a copy of the broadcast packet. For example, terminal 60 may be a mobile vehicle such as an automobile or a train, or a communication device installed in that vehicle.

[0018] Fig. 2 is a diagram showing an example of the hardware configuration of a broadcasting device 10 according to an embodiment of the present invention. The broadcasting device 10 in Fig. 2 includes a drive device 100, an auxiliary storage device 102, a memory device 103, a CPU 104, and an interface device 105, all of which are interconnected via a bus B.

[0019] A program that realizes processing in the broadcasting device 10 is provided by a recording medium 101 such as a CD-ROM. When the recording medium 101 storing the program is set in the drive device 100, the program is installed from the recording medium 101 to the auxiliary storage device 102 via the drive device 100. However, the program does not necessarily have to be installed from the recording medium 101, but may be downloaded from another computer via a network. The auxiliary storage device 102 stores the installed program as well as necessary files, data, etc.

[0020] When an instruction to start a program is received, the memory device 103 reads the program from the auxiliary storage device 102 and stores it. The CPU 104 executes functions related to the broadcasting device 10 in accordance with the program stored in the memory device 103. The interface device 105 is used as an interface for connecting to a network.

[0021] The message generating device 20, the broadcasting device 10, the location information managing device 30, the network information managing device 40, the relay device 50, and the terminal 60 may also have the same hardware configuration as that shown in FIG.

[0022] Fig. 3 is a diagram showing an example of the functional configuration of the location information managing device 30. In Fig. 3, the location information managing device 30 has a location information registration unit 31 and a terminal information response unit 32. These units are realized by processing in which one or more programs installed in the location information managing device 30 are executed by the CPU of the location information managing device 30. The location information managing device 30 also uses a location information management DB 33. The location information management DB 33 can be realized, for example, by using an auxiliary storage device of the location information managing device 30 or a storage device connectable to the location information managing device 30 via a network.

[0023] The location information registration unit 31 registers in the location information management DB 33 records including the terminal name, location information of the terminal 60, a multicast address (EID) corresponding to the division range to which the terminal 60 belongs, and a terminal ID, which are periodically notified from each terminal 60. Among these, the terminal name is, for example, the UUID (Universally Unique Identifier) ​​of the terminal 60, and is identification information of the terminal 60 that the terminal 60 has from the beginning. The terminal ID is identification information that is assigned to the terminal 60 by the relay device 50 that accommodates the terminal 60, and is used by the communication system 1 to uniquely identify the terminal 60. Records that have not been updated for a certain period of time are deleted from the location information management DB 33.

[0024] The terminal information response unit 32 searches the location information management DB 33 for records of terminals 60 whose location information is included in the notification area (for example, a radius of 100 m from (x0, y0)) specified in the inquiry from the broadcasting device 10, and responds to the broadcasting device 10 with the EID and terminal ID of each searched record.

[0025] The location information management DB 33 is a database (storage unit) that stores the terminal name, location information, multicast address (EID) corresponding to the location information (corresponding to a divided range including the location indicated by the location information), and terminal ID of each terminal 60. The location information management DB 33 may be a single database or multiple databases divided according to area.

[0026] Fig. 4 is a diagram showing an example of the functional configuration of the network information management device 40. In Fig. 4, the network information management device 40 has a NW information response unit 41 and a NW information design unit 42. These units are realized by processing in which one or more programs installed in the network information management device 40 are executed by the CPU of the network information management device 40. The network information management device 40 also uses a NW information management DB 43. The NW information management DB 43 can be realized by using, for example, an auxiliary storage device of the network information management device 40 or a storage device connectable to the network information management device 40 via a network.

[0027] The NW information management DB 43 is a database (storage unit) that stores records indicating the relationship between EIDs, relay devices 50, and RLOCs. Note that the correspondence between EIDs and RLOCs is basically fixed unless the network configuration changes.

[0028] In response to an inquiry from the broadcasting device 10 about the RLOC corresponding to the EID, the NW information response unit 41 refers to the NW information management DB 43 and responds with the RLOC.

[0029] The NW information design unit 42 registers records in the NW information management DB 43. Specifically, the NW information design unit 42 acquires topology information and geographic information of the cover area from routers and relay devices 50 in the network N1, which is the core network, and acquires the correspondence between EIDs and location information from the location information management device 30. The NW information design unit 42 uses the acquired information to learn the correspondence between the relay devices 50 and EIDs. The NW information design unit 42 also assigns RLOCs to groups of EIDs (e.g., EIDs 1 to 10, EIDs 11 to 12), and registers the results in the NW information management DB 43. The NW information design unit 42 further transmits the EID-RLOC correspondence to the relay device 50.

[0030] 5 is a diagram showing an example of the functional configuration of the terminal 60. In FIG. 5, the terminal 60 includes a location information acquisition unit 61, an address calculation unit 62, an ID acquisition unit 63, a communication control unit 64, and a client application 65.

[0031] The location information acquisition unit 61 acquires location information (latitude and longitude information) of the terminal 60 from an external device (for example, a GPS antenna).

[0032] The address calculation unit 62 calculates a multicast address (EID) corresponding to the location information based on the location information and joins the multicast group. One example of address calculation is a method of converting the latitude and longitude information down to three decimal places into hexadecimal and specifying the result as the group ID of the multicast address. The address calculation unit 62 sets the calculated multicast address (EID) in the communication control unit 64.

[0033] ID acquisition unit 63 acquires a terminal ID from relay device 50 based on the location information. In this embodiment, the terminal ID depends on the location information, so the terminal ID is acquired based on the location information. However, the terminal ID does not necessarily have to depend on the location information.

[0034] The communication control unit 64 receives the broadcast packet replicated by the relay device 50 by examining the set multicast address (EID) and terminal ID information. The communication control unit 64 transmits the data (notification message) contained in the received broadcast packet to the client application 65. Whether or not the client application 65 can receive the data may be determined by including location information of the broadcast destination in the data portion of the packet, and the client application 65 may determine whether or not to receive the data based on that information.

[0035] Fig. 6 is a diagram showing an example of the functional configuration of the broadcasting device 10. In Fig. 6, the broadcasting device 10 has a request receiving unit 11, a broadcast destination specifying unit 12, a determining unit 13, a filter information generating unit 14, and a broadcasting unit 15. Each of these units is realized by processing in which one or more programs installed in the broadcasting device 10 are executed by the CPU 104.

[0036] The request receiving unit 11 receives a broadcast request from the message generating device 20 .

[0037] The broadcast destination specification unit 12 specifies the terminals 60 located in the destination area and the EIDs and terminal IDs of the terminals 60 by querying the location information manager 30 for terminal information including the multicast addresses (EIDs) and terminal IDs of the terminals 60 located in the destination area included in the broadcast request. The response obtained at this time is in the form of a list of EIDs and terminal IDs. The broadcast destination specification unit 12 also obtains the RLOCs corresponding to the EIDs from the network information manager 40 based on the obtained list of EIDs.

[0038] The determination unit 13 determines the communication model (transmission method) of the broadcast communication for each EID according to the state of the notification destination area. As an example, for a division range (EID) where it is more efficient to perform broadcasting, such as when a large number of terminals 60 (exceeding a preset threshold) exist in the same division range, the determination unit 13 determines to perform broadcasting, and for a division range (EID) where this is not the case, the determination unit 13 determines to perform multicasting.

[0039] The filter information generator 14 generates filter information for limiting the destinations of a broadcast packet, the destination of which is specified by an EID, to terminals 60 located in the destination area among the terminals 60 located in the segmented range corresponding to the EID. That is, since the destination area is not necessarily determined based on the segmented range (rather, it is likely to be determined independently), a certain segmented range may only partially overlap with the destination area. The segmented range corresponding to the EID of a terminal 60 located in the destination area is merely a segmented range at least partially overlapping with the destination area. Therefore, if the destination of a broadcast packet were identified based solely on the EID, the broadcast packet would also be transmitted to terminals 60 located outside the destination area. Therefore, in this embodiment, in order to limit the destinations of a broadcast packet to only terminals 60 located in a portion (range) of a certain divided range that overlaps with the destination area, the filter information generator 14 generates filter information called a Bloom Filter (hereinafter referred to as "BF") based on the terminal IDs, etc., of terminals 60 located in the destination area. Note that when the destination area spans multiple EIDs (divided ranges), a broadcast packet is generated for each EID. Therefore, the BF stored in the broadcast packet is also generated for each EID.

[0040] The broadcast transmitter 15 generates a broadcast packet of a notification message for each EID by including the EID and the BF generated for the EID in the IP header. The broadcast transmitter 15 also encapsulates the broadcast packet for each EID with the RLOC corresponding to the EID, and transmits the encapsulated broadcast packet to the network N1.

[0041] Fig. 7 is a diagram showing an example of the functional configuration of the relay device 50. In Fig. 7, the relay device 50 has an ID management unit 51, a communication information management unit 52, and a forwarding unit 53. Each of these units is realized by processing in which one or more programs installed in the relay device 50 are executed by the CPU of the relay device 50. The relay device 50 also uses a forwarding table 54. The forwarding table 54 can be realized, for example, by using an auxiliary storage device of the relay device 50 or a storage device connectable to the relay device 50 via a network.

[0042] The communication information management unit 52 acquires and manages information necessary for network processing by the relay device 50. As an example, the communication information management unit 52 acquires, from the network information management device 40, an RLOC corresponding to a group of EIDs (e.g., EIDs 1 to 10, EIDs 11 to 12) accommodated by the relay device 50, and uses the acquired RLOC to decapsulate packets. By knowing the RLOC corresponding to itself, the relay device 50 (router) can recognize that a received packet corresponds to its own RLOC and decapsulate the packet. In other words, to remove the encapsulation header, it is necessary to determine whether the destination address of the received packet is its own RLOC. For this purpose, an RLOC corresponding to a group of EIDs accommodated by the relay device 50 is used to decapsulate the packet.

[0043] The ID management unit 51 issues (assigns) a terminal ID to the terminal 60. At this time, the ID management unit 51 registers a record including the assigned terminal ID in association with the EID and terminal name of the terminal 60 in the transfer table 54. The terminal ID may be an ID based on the location, traveling direction, or vehicle type of the terminal 60.

[0044] The forwarding unit 53 obtains information on the next hop to which the broadcast packet will be copied from the forwarding table 54 based on the EID, BF, etc. of the broadcast packet received by the relay device 50, and copies and forwards the broadcast packet. The next hop is the IP address of the destination terminal 60, or a tunnel interface of the mobile network used to transfer the packet to the terminal 60, etc.

[0045] The following describes the processing procedures executed in the communication system 1. Fig. 8 is a sequence diagram for explaining an example of processing procedures related to the assignment of a terminal ID and the updating of the location information management DB 33.

[0046] For example, when the terminal 60 is started up, the location information acquisition unit 61 of the terminal 60 acquires the location information of the terminal 60 (S101). Next, the address calculation unit 62 of the terminal 60 calculates a multicast address (EID) corresponding to the division range to which the location indicated by the location information belongs, based on the location information, and sets the EID in the communication interface of the terminal 60 (S102).

[0047] Next, the ID acquisition unit 63 of the terminal 60 transmits a terminal ID issuance request to the relay device 50 (S103). The issuance request includes the EID corresponding to the terminal 60, the terminal name of the terminal 60, and information on which the terminal ID depends (for example, location information of the terminal 60, information indicating the traveling direction of the terminal 60, the vehicle type of the terminal 60, etc.).

[0048] In response to the terminal ID assignment request, the ID management unit 51 of the relay device 50 generates a terminal ID based on the information included in the assignment request (S104). The terminal ID is expressed, for example, as a bit string (binary number) as shown in FIG.

[0049] 9 is a diagram showing an example of the configuration of a terminal ID. As shown in FIG. 9, the terminal ID includes, for example, a location ID, a direction ID, and a number.

[0050] A Location ID is, for example, identification information corresponding to one area when a division range corresponding to one EID is recursively divided into four equal parts in three stages. In the four divisions, a value expressed as a two-bit bit string is assigned to each area. In the example of FIG. 9, one Location ID is expressed as six bits, consisting of two bits representing the highest area including the area in the third layer corresponding to that one Location ID, two bits representing the area in the second layer including that area, and two bits representing the area in the third layer. In the example of FIG. 9, the Location ID for area "01" in the third layer is "010101."

[0051] The Direction ID is identification information that indicates the traveling direction of the terminal 60 (or the vehicle on which it is mounted). FIG. 9 shows an example in which the traveling direction is classified into eight directions. In this case, since it is sufficient to distinguish between the eight directions, the traveling direction may be indicated by a bit string of 3 bits for the Direction ID, for example. Alternatively, one bit may be assigned to each direction, and the Direction ID may be expressed by a one-hot vector in which only the corresponding direction is set to 1.

[0052] The number is identification information that is assigned in the order of registration of the terminals 60 in the relay device 50 (in the order of assignment of terminal IDs to the terminals 60) in order to uniquely identify each terminal 60. Two expression methods, expression method 1 and expression method 2, are illustrated in FIG.

[0053] Representation method 1 is a method of expressing numbers in binary notation that represents the value of the registration order. In this case, numbers with the same bit set to 1 can occur.

[0054] Representation method 2 is a method of expressing a number in binary notation, where only the bits corresponding to the registration order are set to 1. In this case, there are no numbers where the same bit is 1.

[0055] From the above, for example, the terminal ID of terminal 60 that is located in an area with a Location ID of "010101", has a Direction ID of 0="000", and is first in the registration order is "0101010000001" in the case of Number representation method 1.

[0056] In this way, in order to reduce false positives (misdeliveries), when a broadcast packet is sent, the group of terminals 60 included in the notification area is searched, and terminal IDs are assigned so that the same bit is set for neighboring terminals 60.

[0057] The Location ID may be included in the request for issuance of the terminal ID (may be generated by the terminal 60 based on the location information), or may be generated by the ID management unit 51 based on the location information included in the request for issuance. The Direction ID or the traveling direction of the terminal 60 for determining the Direction ID may be included in the request for issuance of the terminal ID (i.e., may be specified by the terminal 60). The Number may be assigned by the ID management unit 51.

[0058] The configuration of the terminal ID is not limited to the above. For example, the terminal ID does not have to include a Direction ID. Alternatively, the terminal ID may include a bit string indicating the type of device in which the terminal 60 is installed, such as the vehicle type, or may include a bit string indicating other information.

[0059] The ID management unit 51 registers in the transfer table 54 a record that associates the generated terminal ID with the EID and terminal name included in the issuance request.

[0060] 10 is a diagram showing an example of the configuration of the forwarding table 54. As shown in FIG. 10, the forwarding table 54 of a certain relay device 50 stores the EID, terminal name, terminal ID, and next hop for each terminal 60 accommodated by the relay device 50. The EID is an ID corresponding to a division range, and therefore may be common to multiple terminals 60. Furthermore, relay devices 50 corresponding to multiple division ranges may accommodate terminals 60 corresponding to different EIDs. Therefore, records with different EIDs may be registered in the forwarding table 54 of the relay device 50. The value of the next hop can be identified from a packet related to a distribution request from the terminal 60.

[0061] 10, for the sake of convenience, the terminal ID is shown in a simplified format (6 bits), and this also applies hereinafter.

[0062] Next, the ID management unit 51 transmits the generated terminal ID to the terminal 60 that sent the assignment request (S105). Note that steps S101 to S105 are executed at regular intervals for each terminal 60. Alternatively, steps S103 to S105 may be executed every time the location information of the terminal 60 is changed and the multicast address is changed.

[0063] When the ID acquisition unit 63 of the terminal 60 receives the terminal ID, it transmits the terminal name, location information, EID, and terminal ID of the terminal 60 to the location information management device 30 (S106). When the location information registration unit 31 of the location information management device 30 receives this information, it updates the location information management DB 33 based on the information (S107).

[0064] Fig. 11 is a diagram showing an example of the configuration of the location information management DB 33. As shown in Fig. 11, the location information management DB 33 stores, for each terminal 60 to which a terminal ID has been assigned, the terminal name, the location information at the time the terminal ID was assigned, the EID at the time the terminal ID was assigned, and the terminal ID in association with each other. Note that in Fig. 11, for convenience, the EID value is expressed by an abstract symbol (such as "EID9").

[0065] In step S107, if a record matching the received terminal name is stored in the location information management DB 33, the location information registration unit 31 updates the record. If a record matching the received terminal name is not stored in the location information management DB 33, the location information registration unit 31 registers in the location information management DB 33 a record including the terminal name, the received location information, EID, and terminal ID.

[0066] Steps S106 and S107 may be executed at regular intervals, or may be executed when the terminal ID is changed.

[0067] FIG. 12 is a sequence diagram illustrating an example of a processing procedure for transmitting a broadcast packet.

[0068] In step S201, the message generating device 20 transmits a broadcast request including a notification destination area and a notification message to the broadcasting device 10, and the request receiving unit 11 of the broadcasting device 10 receives the broadcast request.

[0069] Next, the broadcast destination specification unit 12 of the broadcasting device 10 queries the location information management device 30 for terminal information including the multicast address (EID) and terminal ID of the terminal 60 located in the destination area included in the broadcast request (S202). This query includes range information indicating the destination area.

[0070] In response to the inquiry, the terminal information response unit 32 of the location information managing device 30 extracts, from the location information management DB 33 (FIG. 11), EIDs and terminal IDs associated with location information relating to positions included in the notification destination area indicated by the range information specified in the inquiry (S203). The extracted EIDs and terminal IDs are EIDs and terminal IDs corresponding to the terminals 60 located in the notification destination area. Next, the terminal information response unit 32 transmits a list of the extracted EIDs and terminal IDs (list of terminal information) to the broadcasting device 10, and the broadcast destination specification unit 12 of the broadcasting device 10 receives the list (S204). As a result, the broadcast destination specification unit 12 can specify the terminals 60 to which the notification message is to be broadcast, the EIDs and terminal IDs of the terminals 60, etc.

[0071] Next, the determination unit 13 of the broadcast device 10 determines the communication model of the broadcast communication (for example, broadcast or multicast) for each EID received by the broadcast destination specification unit 12 (S205). For example, the determination unit 13 compares the number of elements (i.e., the number of terminals 60) with a threshold for each element group having a common EID in the list of terminal information. The determination unit 13 determines that an EID for which the number of elements exceeds the threshold is broadcast, and determines that an EID for which the number of elements does not exceed the threshold is multicast.

[0072] Next, the filter information generation unit 14 calculates a BF for the list of terminal IDs corresponding to each EID in the list of terminal information for each EID determined by the determination unit 13 to be multicast (S206). That is, a BF is calculated for each group of terminal IDs that share a common EID. Therefore, a BF is calculated for each type of EID. One method of calculating a BF is to calculate the logical sum of each terminal ID. In FIG. 11, if the terminal 60 in the first row and the terminal 60 in the second row are included in the notification destination area, the respective terminal IDs are "000001" and "000010". In this case, the value of the BF (logical sum) is "000011". Alternatively, the logical sum of the hash values ​​of each terminal ID may be used as the BF, or the BF may be calculated by other calculation methods such as logical product.

[0073] If the broadcast request includes the traveling direction of terminal 60, filter information generation unit 14 calculates BF based only on the terminal IDs associated with that traveling direction among the terminal IDs corresponding to the EID determined to be multicast by determination unit 13. This allows only terminal 60 to be the broadcast destination while moving in that traveling direction. If the terminal ID includes a vehicle type, etc., and the vehicle type, etc., is also specified in the broadcast request, BF can be calculated using the same process.

[0074] Next, the broadcast destination determination unit 12 of the broadcasting device 10 queries the network information management device 40 for the RLOC corresponding to each EID included in the list of terminal information (one EID if all EIDs are the same) (S207). The NW information response unit 41 of the network information management device 40 identifies the RLOC corresponding to each EID related to the query by referring to the NW information management DB 43, and transmits the identified RLOC to the broadcast destination determination unit 12 (S208).

[0075] Fig. 13 is a diagram showing an example of the configuration of the NW information management DB 43. As shown in Fig. 13, the NW information management DB 43 stores a router ID and an RLOC for each EID. The router ID is identification information of the relay device 50 that accommodates the EID. The RLOC is an RLOC that corresponds to the EID (corresponding to a group that includes the EID). Note that in Fig. 13, the EID value is expressed in an abstract manner for convenience.

[0076] Next, the broadcast sending unit 15 of the broadcast communication device 10 generates a broadcast packet of a notification message for each EID of the broadcast destination, with the EID as the destination IP address and the BF associated with the EID included in the header, and encapsulates the broadcast packet with the RLOC corresponding to the EID (S209). Figure 14 shows an example of an encapsulated broadcast packet.

[0077] Next, the broadcast transmitter 15 transmits the encapsulated broadcast packet to the relay device 50 corresponding to the RLOC (S210). If there are multiple EIDs as broadcast destinations, multiple broadcast packets are transmitted.

[0078] 15 is a sequence diagram illustrating an example of a processing procedure for forwarding a broadcast packet. Step S210 in FIG. 15 corresponds to step S210 in FIG.

[0079] When the forwarding unit 53 of the relay device 50 corresponding to the RLOC of the broadcast packet receives the broadcast packet (S210), it decapsulates the broadcast packet (S301).

[0080] Next, the forwarding unit 53 obtains the next hop of the broadcast packet corresponding to the EID and BF of the broadcast packet from the forwarding table 54 (FIG. 10) (S302). Specifically, the next hop of the record including the EID that matches the EID and the terminal ID that matches the BF is obtained. For example, if the BF is the logical sum of terminal IDs, the terminal ID that matches the BF is the terminal ID whose logical product with the BF matches the terminal ID. Specifically, if the BF is "000011", "000001", "000010", and "00011" can match the BF.

[0081] In this way, the BF is used as information for identifying the group of terminals 60 that will be the broadcast destinations (delivery destinations) of the notification message. In the case of representation method 1 in FIG. 9, there is a possibility that a terminal 60 that is not originally a broadcast destination may also be set as a broadcast destination. Specifically, if a terminal 60 whose registration order is 1 and a terminal 60 whose registration order is 2 are original broadcast destinations (terminals 60 included in the notification destination area), the BF (logical product) of these Numbers is "0011." In this case, the Number of the terminal 60 whose registration order is 3 is "0011," which matches the BF. As a result, the terminal 60 whose registration order is 3 will also be set as a broadcast destination, but in this embodiment, such erroneous delivery is allowed to improve scalability. Note that such erroneous delivery does not occur in the case of representation method 2 in FIG. 9.

[0082] Next, the forwarding unit 53 forwards a copy of the broadcast packet to the terminal 60 corresponding to the acquired next hop (S303).

[0083] The above processing procedure realizes, for example, broadcast transmission as shown in Fig. 16. Fig. 16 shows an example in which the broadcast packet shown in Fig. 14 is transmitted. The RLOC of the broadcast packet is RLOC1. In Fig. 16, relay device 50-1 and relay device 50-2 correspond to RLOC1. Therefore, the broadcast packet is forwarded by relay device 50-1 and relay device 50-2.

[0084] Furthermore, the EID of the broadcast packet is EID10, and the BF is 000011. Each of relay device 50-1 and relay device 50-2 corresponds to EID10 and transmits the broadcast packet to terminal 60 that matches the BF. Note that the binary numbers in the ellipses representing each terminal 60 indicate the terminal ID of each terminal 60. As a result, in FIG. 16, the packet is delivered to terminal 60-2 and terminal 60-3. Terminal 60-4 corresponds to EID10, but the terminal ID does not match the BF (for example, because it is located outside the notification destination area), so the broadcast packet is not delivered.

[0085] As described above, according to this embodiment, it is possible to flexibly select broadcast destinations based on EID and BF. That is, it is possible to set only some of the terminals 60 within the division range corresponding to the EID as broadcast destinations. Furthermore, since there is no need to divide the grid into smaller sections, it is possible to suppress an increase in management information. As a result, it is possible to reduce the load of information management required to achieve flexible broadcasting, and it is possible to reduce the amount of communication on the C-Plane.

[0086] In addition, by encapsulating broadcast packets using RLOCs that group EIDs, the number of routes for broadcast packets can be reduced.

[0087] In addition, by fixing the correspondence between EID (location-related address) and RLOC (address of access network router), a static multicast tree can be constructed, reducing the amount of communication on the C-Plane.

[0088] In this embodiment, the EID is an example of a first multicast address, and the RLOC is an example of a second multicast address.

[0089] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0090] 1. Communication Systems 10 Broadcasting equipment 11 Request Receiver 12 Broadcast destination identification section 13 Judgment section 14 Filter information generation unit 15 Broadcast transmission section 20 Message Generator 30 Location information management device 31 Location information registration unit 32 Terminal information response part 33 Location information management DB 40 Network information management device 41 Network information response section 42 NW Information Design Department 43 NW information management DB 50 Relay Device 51 ID Management Department 52 Communications Information Management Department 53 Transfer Unit 54 Forwarding Table 60 devices 61 Location information acquisition unit 62 Address Calculation Unit 63 ID acquisition part 64 Communication control unit 65 client apps 100 Drive device 101 Recording media 102 Auxiliary storage 103 Memory Device 104 CPU 105 Interface Device B Bus

Claims

1. A communication system including a broadcasting device that transmits packets and a plurality of relay devices that accommodate terminals that are candidates for destinations of the packets, The broadcasting device a broadcast destination specifying unit configured to specify the terminals located in a specific geographical area based on the location information of the terminals; a broadcast transmission unit configured to transmit a broadcast packet addressed to a first multicast address corresponding to a divided range that at least partially overlaps a specific geographical range, among first multicast addresses for each divided range obtained by dividing a certain geographical range into a plurality of ranges, and including filter information for identifying the terminals located in the specific geographical range; and The relay device corresponding to the first multicast address, which is the destination, a forwarding unit configured to forward the broadcast packet to the terminal identified based on the filter information included in the broadcast packet among the terminals accommodated by the relay device; A communication system comprising:

2. the broadcast transmission unit is configured to encapsulate the broadcast packet with a second multicast address corresponding to the first multicast address that is the destination, among second multicast addresses each corresponding to one or more of the first multicast addresses, and transmit the broadcast packet to the relay device corresponding to the second multicast address.

2. The communication system according to claim 1.

3. the broadcast transmission unit is configured to transmit the broadcast packet including the filter information based on binary identification information that uniquely identifies the terminal located in the specific geographical range, the forwarding unit is configured to forward the broadcast packet to a terminal, among the terminals accommodated by the relay device, to which identification information specified based on the filter information included in the broadcast packet is assigned.

3. The communication system according to claim 1 or 2.

4. a broadcast destination specifying unit configured to specify terminals located in a specific geographical area based on location information of the terminals; a broadcast transmission unit configured to transmit a broadcast packet addressed to a first multicast address corresponding to a divided range that at least partially overlaps a specific geographical range, among first multicast addresses for each divided range obtained by dividing a certain geographical range into a plurality of ranges, and including filter information for identifying the terminals located in the specific geographical range; A broadcasting device comprising:

5. A communication method executed by a broadcasting device that transmits a packet and a plurality of relay devices that accommodate terminals that are candidates for destinations of the packet, comprising: The broadcasting device a broadcast destination specifying step of specifying the terminals located in a specific geographical area based on the location information of the terminals; a broadcast transmission procedure for transmitting a broadcast packet to a first multicast address corresponding to a divided range that at least partially overlaps a specific geographical range, among first multicast addresses for each divided range obtained by dividing a certain geographical range into a plurality of ranges, the broadcast packet including filter information for identifying the terminals located in the specific geographical range; Run The relay device corresponding to the first multicast address, which is the destination, executing a forwarding procedure for forwarding the broadcast packet to the terminal identified based on the filter information included in the broadcast packet, among the terminals accommodated by the relay device; A communication method comprising:

6. a broadcast destination specifying step of specifying terminals located in a specific geographical area based on location information of the terminals; a broadcast transmission procedure for transmitting a broadcast packet to a first multicast address corresponding to a divided range that at least partially overlaps a specific geographical range, among first multicast addresses for each divided range obtained by dividing a certain geographical range into a plurality of ranges, the broadcast packet including filter information for identifying the terminals located in the specific geographical range; A program characterized by causing a computer to execute the above.

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