JP4456985B2 - Mobile communication network - Google Patents

Description

  The present invention relates to a mobile communication network that enables a client terminal existing in a mobile body such as an automobile, a train, a ship, and an aircraft to access the Internet.

  In mobile communication on the Internet, as a conventional technique, for example, as a method for continuing IP communication for mobile communication terminals moving in different subnets, there is mobile IP (Mobile IP) defined in IETF standard recommendation RFC2002.

  Mobile IP seems to be connected to the network (home network) to which the mobile communication terminal originally belongs from the host that is the communication partner even when the mobile communication terminal is connected to an arbitrary subnet on the network. It is a method to show.

  An example of the operation of Mobile IP will be described with reference to FIG. In FIG. 5, a mobile communication terminal (Mobile Node: hereinafter abbreviated as MN) 50 is a mobile communication terminal that moves between networks. A communication destination node (Correspondent Node: hereinafter abbreviated as CN) 52 is a host that is a communication partner of the MN 50. In the home network 54 to which the MN 50 originally belongs, a home agent (hereinafter referred to as HA) 56 manages the communication of the MN 50. In the visited network (subnet) 58 that the MN 50 is currently visiting temporarily, a foreign agent (hereinafter referred to as FA) 60 manages the communication of the MN 50. Further, in the network (subnet) 62 that the MN 50 visits next, the foreign agent (FA) 64 manages the communication of the MN 50.

  The IP network 66 is a network serving as a relay network that connects them. When the MN 50 is connected to the visited network 58, the HA 56 receives the location information indicating which network the MN 50 is currently visiting, and information on the FA 60 that manages the visited network 58 (FA IP address). ) And set up its own network interface so that it can receive IP packets addressed to the MN 50.

  When the IP packet transmitted by the CN 52 to the MN 50 arrives at the home network 54, the HA 56 receives the packet instead of the MN 50 and forwards it to the visited network 58 that the MN 50 is currently visiting. At this time, the HA 56 encapsulates the IP packet from the CN 52 into an IP packet addressed to the FA 60 and distributes it. When the FA 60 receives this encapsulated packet, the FA 60 takes out the original IP packet addressed to the MN 50 and delivers it to the MN 50.

  On the other hand, when an IP packet is transmitted from the MN 50 to the CN 52, it is transmitted directly using the original address of the MN 50. As a result, the MN 50 and the CN 52 can communicate without being aware that the MN 50 is moving in the network. There is also a form in which the MN 50 itself has the function of the FA 60. At this time, the MN 50 acquires and uses an address that can be used in the visited network 58 every time it moves.

  Furthermore, when the MN 50 moves to another visited network 62, the MN 50 notifies the HA 56 that it has moved through the FA 64 that manages the other visited network 62 together with address information of the FA 64. When the HA 56 receives a packet addressed to the MN 50 from the CN 52, the HA 56 encapsulates it and transfers it to the FA 64. The FA 64 delivers the transferred packet to the MN 50. In this way, the MN 50 can continue communication while moving through the visited network (see the prior art in Patent Document 1).

Japanese Patent Laid-Open No. 2001-274834

  However, the technology using the conventional mobile IP requires a special device or special software such as a mobile router such as HA or FA in order to realize the communication protocol, and the system becomes complicated. For this reason, there is a problem that an increase in network load as a whole system, a decrease in reliability, or a complicated security management is caused, and the cost for realizing the system increases.

  Therefore, an object of the present invention is to provide a mobile communication network having a simple configuration that enables communication between the mobile body and the Internet even when the mobile body moves between different segments.

  In order to achieve the above object, the present invention comprises a moving segment existing in a moving body and two or more fixed segments arranged on the ground, and the moving segment and the two or more fixed segments have the same address. A mobile communication network configured in a system, wherein each of the two or more fixed segments includes a fixed gateway accessible to the Internet network, and at least one connected to the fixed gateway and capable of communicating with the mobile segment And the fixed segment side IP addresses of the fixed side gateways of the two or more fixed segments are all set to be the same, and the mobile segment exists in the mobile body. A mobile gateway accessible to one or more client terminals; A transmission / reception unit connected to a mobile gateway and capable of communicating with the access point, wherein the mobile gateway uses an IP address of the default gateway as an IP address of the fixed gateway, and an IP address of the fixed gateway And using the recognized MAC address as the MAC address of the default gateway of the mobile gateway, whereby the client terminal is connected to the Internet via the fixed gateway. It is characterized by making the network accessible.

  Further, the present invention includes a moving segment that exists in a moving body and two or more fixed segments arranged on the ground, and the moving segment and the two or more fixed segments are configured to have the same address system. Each of the two or more fixed segments includes a fixed gateway that can access the Internet network, and at least one or more access points that are connected to the fixed gateway and can communicate with the mobile segment. The fixed segment side IP addresses of the fixed side gateways of each of the two or more fixed segments are set to be the same, and the mobile segment is one or more client terminals existing in the mobile body. And can be communicated with the access point. A fixed-gateway MAC corresponding to the IP address of the fixed-side gateway, in which the IP address of the default gateway is set as the IP address of the fixed-side gateway. Recognizes the address and uses the recognized MAC address as the MAC address of the default gateway of the client terminal that can access the transmission / reception unit, thereby allowing the client terminal to access the Internet network via the fixed gateway. It is characterized by enabling.

  As described above, according to the mobile communication according to the present invention, the fixed gateway IP address of the fixed segment is set to be the same, and the default gateway of the client terminal that can access the mobile gateway or the transceiver unit Since the IP address of the fixed segment of the fixed segment that is the same IP address is the IP address of the fixed segment, even if the mobile point moves, the access point that can be communicated by the transmitting / receiving unit of the mobile segment changes. The client terminal that can access the mobile gateway or the transmission / reception unit can perform the same operation as if it were transferred to the same fixed gateway. Thereby, the client terminal existing in the mobile body can be connected to the Internet network via the fixed gateway.

  In the mobile communication network according to the present invention, the mobile segment has at least a MAC address database storing the MAC address of the fixed gateway and the IP address of the fixed segment in association with each other, and an access that allows the transceiver to communicate A MAC address registration unit capable of registering a MAC address of a fixed side gateway of a fixed segment to which the point belongs based on the MAC address database; and a client terminal accessible to the mobile side gateway or the transmission / reception unit, Preferably, the MAC address registration unit is configured to recognize the MAC address of the fixed gateway, and the transmission / reception unit is configured to be able to recognize the communicable access point. The MAC address database stores information on the one or more access points in association with at least the MAC address of the fixed gateway of the fixed segment to which the client belongs, and the client terminal that can access the mobile gateway or the transceiver unit is It is more preferable that the MAC address of the fixed gateway is recognized based on information on the communicable access point recognized by the transmission / reception unit. Further, it is preferable that the access point is arranged along a predetermined movement route of the mobile body.

  In addition, the mobile communication network according to the present invention stores, as location information of the mobile unit, information on an access point with which the mobile unit can communicate or a fixed segment to which the mobile unit belongs, and location information management connected to the Internet The transmission / reception unit transmits information regarding the recognized transmittable access point to the location information management unit, and the location information management unit is configured to detect the location of the mobile unit based on the received information about the access point. It is preferable to be configured to store information, and it is preferable that the position information management unit is configured to store position information of the moving body.

  The mobile communication network according to the present invention can acquire the position information of the mobile body by accessing the position information management unit in this way. The acquired position information of the mobile object can be used for identifying a destination IP address necessary for communication from the Internet to the mobile object in addition to the purpose of grasping and managing the position information of the mobile object.

  Furthermore, the mobile communication network according to the present invention further includes a location information management unit that stores an IP address for communication access from the Internet network toward the mobile segment as information relating to the location of the mobile, The information management unit transmits a request signal for communication confirmation to the client terminal accessible to the mobile gateway or the transmission / reception unit via the fixed gateway and access point of the fixed segment to which the mobile unit belongs, and the mobile When the client terminal accessible to the side gateway or the transmission / reception unit receives the request signal for the communication confirmation, it returns a response signal communicable to the location information management unit, and the location information management unit When the response signal is received, the response signal is directed to the moving segment. It is preferably configured to store an IP address for communication access from the Internet network.

  As described above, the mobile communication network according to the present invention does not require a special device such as a mobile router or a communication protocol as in the conventional technology using mobile IP, and the mobile communication network moves between different segments. Even in this case, it is possible to provide a mobile communication network having a simple configuration that enables communication between the mobile body and the Internet, and the following effects can be obtained.

  That is, the communication of the mobile communication network according to the present invention is realized by a combination of only general IP protocols that have been widely used in general Internet communication that does not involve movement of devices. Therefore, a device dedicated to mobile communication for realizing mobile communication and a special communication protocol for mobile communication are not particularly required, and the system can be realized very easily.

  The mobile communication network according to the configuration of the present invention can be realized in a simpler manner and the system configuration is not complicated as compared with a mobile communication system using a mobile IP or IPv6 address space. Mobile communication can be realized.

  The mobile communication network according to the present invention is a mobile communication network in which operation forms such as operation routes and operation times are scheduled in advance, such as automobiles, trains, ships, and aircrafts in general passenger business and cargo business. When accessing the Internet from an existing client terminal, or from a client terminal existing in a specified moving body, for example, even if it is a private car, the destination is easily predicted like a car traveling on a highway This is effective when accessing the Internet.

  In addition, the mobile communication network system according to the configuration of the present invention has a packet loss time of several hundred milliseconds to one to two or several seconds due to the switching response time of the wireless system, that is, packets are transmitted and received. This is effective for applications on the Internet that cannot accept the time span for making retransmission judgments. A specific application is access to a Web server access or a mail server in Internet access, and practically does not affect the user. Even for packet data that is transmitted and received continuously, since measures such as providing a data buffer in the application layer are taken, practical communication is possible even with the mobile communication network system according to the present invention. Is possible.

  As described above, according to the present invention, even when a mobile object moves between different segments without requiring a special device such as a mobile router or a communication protocol as in the conventional technique using mobile IP. It is possible to provide a mobile communication network having a simple configuration that enables communication between the mobile body and the Internet.

BEST MODE FOR CARRYING OUT THE INVENTION

  Next, an embodiment of a mobile communication network according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a mobile communication network configuration according to the present embodiment. In the mobile communication network according to the present embodiment, when the mobile 10 is, for example, a train, the client terminals 20A, 20B,... Existing in the train that is the mobile 10 in the train are configured in a global IP address space. The Internet X that is an IP network is accessed, and the mobile segment 10A disposed on the mobile body 10, the two or more fixed segments 12A, 12B,. And a location information server 30 that stores location information of the mobile unit 10 and a destination address when accessing the mobile segment 10A from the Internet X. In addition to the mobile segment 10A, there are client terminals 20A, 20B,... And a user segment 10B that can access the mobile segment 10A.

  The moving segment 10A and the two or more fixed segments 12A, 12B,... Are composed of a private IP address space composed of a common subnet having the same address system, and in this embodiment, 192.168 .. 1/24 is assigned. The IP address of Internet X is managed by an IP address management organization that exists publicly or semi-publicly, and is usually individually designated as a fixed IP address that does not overlap in the Internet network via an Internet connection service provider (ISP). The IP address of the private IP address space configured by the mobile segment 10 and the two or more fixed segments 12A, 12B... Is connected by the communication system operator of the mobile communication network according to the present embodiment. The IP address can be freely determined according to the system operation guidelines. On the Internet X, there are a Web server 28 and a general user terminal 29 that can be accessed by at least the client terminals 20A and 20B as communication targets. Communication between these fixed segments 12A, 12B..., The position information server 30, the Web server 28, and the general user terminal 29 is performed using a global IP address by wired communication such as an optical fiber or a metal line or various wireless communication.

  Each of the fixed segments 12A, 12B... Has the same configuration. The fixed segment 12A includes a first gateway (hereinafter referred to as “first GW”) 14A capable of accessing the Internet X and first to third access points (hereinafter referred to as “first GW”) connected to the first GW 14A and capable of communicating with the mobile segment 10, respectively. 16A, 16B, 16C) and a first control unit 18A that controls at least the first to third APs 16A, 16B, 16C. Similarly, each of the fixed segments 12B is defined as a second GW 14B, fourth to sixth APs 16D, 16E, 16F, and a second control unit 18B.

  The first GW 14A and the second GW 14B function as a dynamic IP masquerade (NAPT) that converts a private IP address in the mobile segment 10A into a global IP address, and a static for converting the global IP address into a private IP address. IP masquerade function or multi-NAT function. Since the IP addresses on the LAN side, that is, the subnet side of the first GW 14A and the second GW 14B are private IP address spaces as described above, the communication system operator according to the present embodiment can freely determine the IP addresses. In the mobile communication network according to the present embodiment, the first GW 14A and the second GW 14B are all assigned the same private IP address 192.168.1.251, which allows the Internet from the mobile segment 10A to be described later. IP communication to X can be easily realized. The communication ports of the private IP addresses of the first GW 14A and the second GW 14B are assigned different serial numbers, which are physically written so as not to overlap each other when the gateway device is manufactured, as MAC addresses. On the other hand, different global IP addresses such as 201.202.204.12 and 201.202.205.13 are designated by the ISP as global IP addresses on the WAN side of the first GW 14A and the second GW 14B, that is, the Internet X side. Has been.

  Each of the first control unit 18A and the second control unit 18B includes an IP address 192.168.2.211 of the mobile GW 22 existing in the mobile segment 10A described later, and a MAC address database (DB) 19A having the MAC address as a field. And 19B are connected. In addition, each of the first GW 14A and the second GW 14B includes ARP tables 17A and 17B registered in association with the IP address 192.168.1.211 of the mobile GW 22 of the accessible mobile body 10 and its MAC address. The MAC addresses registered in the ARP tables 17A and 17B are always updated to the latest one as will be described later as the mobile body 10 moves. Individual private IP addresses are assigned to the first control unit 18A, the second control unit 18B, and the first to sixth APs 16A to 16F, respectively. 1st thru | or 6th AP16A thru | or 16F are arrange | positioned so that the mobile body 10 can communicate with either AP along the direction to which the mobile body 10 moves. The first control unit 18A, the first GW 14A, the second AP 16B, and the MAC address DB 19A are connected by wire, but the second AP 16B, the first AP 16A, and the third AP 16B are connected wirelessly. Similarly, the second control unit 18B, the second GW 14B, the fifth AP 16E, and the MAC address DB 19B are connected by wire, but the fifth AP 16E, the fourth AP 16D, and the sixth AP 16F are connected by radio.

  The mobile segment 10A is connected to the mobile side GW 22 and the mobile side gateway (GW) 22 that can be wirelessly accessed with the client terminals 20A, 20B... In the user segment 10B, and can communicate with the first to sixth APs 16A to 16F. The transmission / reception part 24 and the movement side control part 26 which controls operation | movement of the transmission / reception part 24 grade are provided. A MAC address database (DB) 21 having the private IP address and the MAC address of each of the first GW 14A and the second GW 14B as fields is connected to the mobile-side control unit 26. In the present embodiment, there are records having the same private IP address 192.168.1.251 and different MAC addresses as fields in the first GW 14A and the second GW 14B, respectively, and AP identification information is also stored. In addition, the mobile side GW 22 is set with 192.168.1.251, which is a common IP address in each of the first GW 14A and the second GW 14B, as the IP address of the default gateway on the mobile segment side. Further, the mobile side GW 22 is provided with an ARP table 23 in which the default gateway IP address 192.168.1.251 and the accessible MAC address of the first GW 14A or the second GW 14B are registered in correspondence with each other. The MAC address registered in the ARP table 23 is always updated to the latest one as will be described later as the mobile body 10 moves.

  In the user segment 10B, client terminals 20A, 20B... Exist and are connected to the mobile GW 22 by radio. The address space of the user segment 10B is composed of a private IP address space different from a private IP address space composed of a common subnet in the mobile segment 10A, two or more fixed segments 12A, 12B,. 2/24 is assigned. In the mobile GW 22, two different private IP address spaces, that is, in the communication network according to the present embodiment, two different subnets between 192.168.8.2/24 and 192.168.1 / 24 are both set. The function to route in the direction is set. Further, 192.168.2.211 is set as the IP address on the user segment side of the mobile GW 22 and the IP address on the user segment side of the mobile GW 22 is set as the default GW for the client terminals 20A, 20B. 192.168.2.211 is set.

  Next, the operation of the mobile communication network according to the present embodiment will be described. First, the case where a packet is transmitted from the client terminal 20A existing in the user segment 10B of the mobile body 10 to the Web server 28 connected to the Internet X will be described based on the sequence flow shown in FIG. First, a case where the transmitting / receiving unit 24 of the mobile body 10 is present in an area where it can communicate with the third AP 16C will be described. First, the mobile-side control unit 26 transmits a request signal for recognizing the access point belonging to the transmission / reception unit 24 (S100). Based on the request signal, the transmission / reception unit 24 recognizes the access point to which it belongs in order to identify the access point to which it belongs and can communicate. A transmission start request signal is transmitted from the transmitter / receiver 24 to a peripheral access point, for example, the third AP 16C and the second APS 16B and the fourth APS 16D to which the surrounding radio waves may reach (S102). Each access point that has received the communication start request signal from the transmission / reception unit 24 returns a communication start response signal to the transmission / reception unit 24 (S104). The transmission / reception unit 24 determines the AP to which it belongs according to an algorithm for selecting and determining the access point of the communication partner that has been previously determined as a function of the transmission / reception unit 24. In general, an AP that has a strong radio wave reception level and can secure a good communication state is selected, and the identification information of the access point to which it belongs is acquired. In FIG. 1, a situation where the transmission / reception unit 24 belongs to the third AP 16C is indicated by a solid line, and the transmission / reception unit 24 acquires information indicating that the transmission / reception unit 24 belongs to the third AP 16C as specific contents of the identification signal. .

  Next, the transmission / reception unit 24 returns a response signal to the request signal for recognizing the access point to which it belongs to the moving side control unit 26 (S106). This signal includes the received identification information of the belonging third AP 16C. The mobile-side control unit 26 uses the MAC address DB 21 to determine the IP address 192.168.1.251 of the first GW 14A of the first fixed segment to which it belongs and the MAC address DB 21 from the identification information of the third AP 16C included in the response signal. Information relating to the address is extracted, and the MAC address information is registered in the ARP table 23 of the mobile GW 22 (S108). On the other hand, the first control unit 18A extracts the IP address 192.168.1.211 of the mobile GW 22 and information about the MAC address from the first GW 14A using the MAC address DB 19A, and extracts the MAC address information from the first GW 14A. Are registered in the ARP table 17A (S110).

  The operations in steps 100 to 110 are performed at regular intervals. The specific repetition period of these steps is optimally determined by the moving speed of the moving object, the distance between the first AP to the sixth AP arranged on the ground, the system response time of the wireless communication system, etc. It is governed by factors that are physically unavoidable, such as the switching response time of wireless communication systems, and is practically a time interval of several hundred milliseconds to several seconds.

  Thus, since the operation | movement of step 100-110 is performed for every fixed period, when the mobile body 10 moves to the area | region where the transmission / reception part 24 can communicate with 4th AP16D, it operate | moves similarly as follows. . The movement-side control unit 26 issues a request signal for recognizing the access point belonging to the transmission / reception unit 24 (S100). Based on the request signal, the transmission / reception unit 24 obtains information that it belongs to the fourth AP 16D (S102 ′ and S104 ′). The transmission / reception unit 24 returns a response signal to the request signal for recognizing the access point to which it belongs to the moving side control unit 26 (S106 ′). This signal includes the received identification information of the belonging fourth AP 16D. The mobile side control unit 26 uses the MAC address DB 21 to identify the IP address 192.168.1.251 of the second GW 14B of the second fixed segment to which it belongs and the MAC address DB 21 from the identification information of the fourth AP 16D included in the response signal. Information relating to the address is extracted, and the MAC address information is registered in the ARP table 23 of the mobile GW 22 (S108 ′). On the other hand, the second control unit 18B extracts the IP address 192.168.1.211 of the mobile GW 22 and information about the MAC address from the second GW 14B using the MAC address DB 19B, and extracts the MAC address information from the second GW 14B. Are registered in the ARP table 17B (S110 '). Therefore, the mobile side GW 22 stores the MAC address of the fixed segment GW to which the communicable AP always belongs, and the fixed segment GW has the mobile side GW 22 to which the fixed segment AP to which the AP belongs can be connected. Are always stored.

  Therefore, the mobile side GW 22 stores the MAC address of the fixed segment GW to which the communicable AP always belongs, and the fixed segment GW has the mobile side GW 22 to which the fixed segment AP to which the AP belongs can be connected. Are always stored. These MAC addresses are constantly updated to the latest data for securing a communication path at a time interval of about several hundred milliseconds to several seconds. The time for the transceiver unit 24 of the mobile unit 10 to switch the wireless connection from the third AP 16C to the fourth AP 16D depends on the system response time of the wireless communication system, but here a timer for packet retransmission of general IP communication Considering the time and the like, it is considered that the time is from several hundred milliseconds to 1 to 2, 3 to several seconds. That is, in the mobile communication network according to the present invention, a time width of about several hundred milliseconds to one to two or several seconds generated due to a physically unavoidable factor such as a switching response time of a wireless communication system. There is a packet loss time, that is, a time span in which a packet cannot be transmitted / received and retransmission is determined. However, this time span has practically no effect on users in normal Internet access such as access to a Web server access or a mail server. Even for packet data and the like that are continuously transmitted and received, there is no problem in performing practical communication because measures such as providing a data buffer in the application layer are taken.

  If the operations in steps 100 to 110 described above cannot be performed, a prompt communication path cannot be secured. As an example, when the mobile 10 moves and switches the wireless connection from the third AP 16C to the fourth AP 16D, that is, the mobile GW 22 does not store the MAC address of the second GW 14B of the second fixed segment 12B to which the communicable AP belongs ( Consider the case where there is no S108 ′. The packet transmitted from the mobile GW 22 to the second GW 14B of the second fixed segment 12B has a destination private IP address of 192.168.1.251 even though the transmission / reception unit 24 belongs to the fourth AP 16D. Although the destination MAC address remains the MAC address of the first GW 14A, the packet is transmitted to the second fixed segment 12B. Since the packet that arrived in the second fixed segment 12B has the destination private IP address 192.168.1.251, it seems to go to the second GW 14B, but this packet is transmitted to the destination MAC address by unicast communication. For this reason, since the MAC address of the first GW 14A does not exist in the second fixed segment 12B, the packet is not transmitted to the second GW 14B and is discarded. A state in which communication is disabled due to such a discrepancy between the destination IP address and the destination MAC address is called “network black fall”, and the packet sent to the network is discarded, but the sending side I don't notice immediately. The sending side notices this until a timeout occurs due to a TCP connection or other session-related traffic interruption. The time-out time varies depending on the IP communication application and the system time-out time of the midway route. Generally, the time-out time of the dynamic cache of the ARP table 23 is 120 seconds as a standard. ing. That is, in the mobile GW 22, even if the transmission / reception unit 24 belongs to the fourth AP 16D, the packet transmitted from the mobile GW 22 to the second GW 14B is discarded at least for 120 seconds when the dynamic cache of the ARP table 23 times out. Alternatively, when the address 192.168.1.251 of the ARP table 23 is a static cache (step of S108), the ARP table 23 always keeps a packet transmitted from the mobile GW 22 to the second GW 14B without being timed out. It will be destroyed.

  Next, when the mobile unit 10 is in an area where the transmission / reception unit 24 can communicate with the third AP 16C, the client terminal 20A with the IP address 192.168.2.245 is connected to the Internet X by the Web server 28. When a packet destined for the IP address is formed and transmitted to the mobile GW 22 (S112), the transmitted packet is first addressed to the address 192.168.2.211 of the user segment side communication port of the mobile GW 22 Is routed to the address 192.168.1.211 of the mobile segment side communication port of the mobile side GW22 by the routing function of the mobile side GW22, and the IP address of the default gateway on the mobile segment side of the mobile side GW22 is Because it is set as 192.168.1.251 Packet from the client terminal 20A is the IP address 192.168.2.245 is sent to the address 192.168.1.251. At this time, since the MAC address of the first GW 14A is stored in the ARP table of the mobile side GW 22, the transmitted packet is transmitted toward the first GW 14A, and the mobile side GW 22 → the mobile side control unit 26 → the transmission / reception unit 24 → third AP 16C → second AP 16B → first control unit 18A → first GW 14A (S114). A packet that has reached the first GW 14 is subjected to a routing process by using a dynamic IP masquerade (NAPT) function that converts the private IP address of the mobile segment 10A into a global IP address on the Internet side, which the first GW 14A has. X is transmitted to the Web server 28 (S116). Thereby, the packet can be transmitted from the client terminal 20A in the mobile body 10 to the Web server 28 connected to the Internet X. Conversely, since the MAC address of the moving side GW is registered in the ARP table 17A of the first GW 14A, the transmission / reception unit 24 of the mobile 10 can communicate with the first AP to the third AP 16A to 16C of the first fixed segment 12A. As long as the mobile unit 10 exists, the client terminal 20A transmits the reverse packet from the Web server 28 to the first GW 14A → first control unit 18A → second AP 16B → third AP 16C → transmission / reception unit 24 → moving side control unit 26 → moving It can be received by transferring with the side GW 22.

  When the mobile unit 10 moves to an area where the transmission / reception unit 24 can communicate with the fourth AP 16D, the packet to be transmitted is the mobile side GW 22 → the movement side control unit 26 → the transmission / reception unit 24 → the fourth AP 16D → the fifth AP 16E → the second control unit. 18B → second GW 14B and then transmitted to the Internet X to reach the Web server 28.

  Further, as described above, the mobile control unit 26 receives the response signal from the transmission / reception unit 24 in step 106, and this signal includes the received identification information of the third AP 16C to which it belongs. Therefore, the movement control unit 26 uses the IP address 201.202.206.14 of the position information server 30 existing in the Internet X as the destination of the identification information of the third AP 16C indicating the access point to which the moving body 10 belongs. An information packet is created, and the packet is transferred to the location information server 30 via the first GW 14A (S120). When the location information server 30 receives the train location information packet, the location information server 30 stores the area communicable with the third AP 16C as the location information of the mobile body 10, and the user accesses the location information server 30 to access the location information server 30. Location information can be acquired. The acquired location information of the mobile unit 10 is used for grasping and managing the location information of the mobile unit, and is a destination IP for communication from the Internet X to the client terminals 20A, 20B,. It can be used as an address or a destination IP address for communication from the Internet X to an IP device existing in the moving segment of the moving body 10.

  Next, an operation when a packet is transmitted from the general user terminal 29 connected to the Internet X to the client terminal 20A existing in the user segment 10B of the mobile unit 10 will be described based on the sequence flow shown in FIG. First, by performing steps 100 to 110 at regular intervals as described above, the MAC address of the first GW 14A is registered in the ARP table of the mobile GW 22, and the MAC address of the mobile GW 22 is registered in the first GW 14A. And The location information server 30 transmits an ICMP echo request packet to the global IP address 201.202.204.12 of the first GW 14A at regular intervals (S200). When the first GW 14A receives the ICMP echo request packet, the first GW 14A reaches the address 201.202.204.12 by converting the global IP address into a private IP address based on the static IP masquerade function or the multi-NAT function. The destination of the ICMP echo request packet is converted to the address 192.168.1.211 of the mobile GW 22 and transmitted (S202). When the mobile GW 22 receives the ICMP echo request packet received from the first GW 14A, it returns an ICMP echo response packet to the first GW 14A (S204). When the first GW 14A receives the ICMP echo response packet from the mobile GW 22, the first GW 14A transmits the ICMP echo response packet to the use location information server 30 by the operation of the static IP masquerade function or the multi-NAT function of the first GW 14A (S206). . By receiving the ICMP echo response packet from the first GW 14A, the location information server 30 assumes that the current location of the mobile unit 10 is in an area where it can communicate with the first to third APs 16A to 16C of the first fixed segment 12A. The global IP address of the first GW 14A or the IP address in the subnet assigned to the global IP address side of the first GW 14A is stored as an address for accessing the mobile GW 22 from the Internet X at that time. If the ICMP echo reply packet cannot be received, it can be seen that the mobile 10 does not exist in the fixed segment 12A. Therefore, the location information server 30 can identify the location of the mobile 10 by transmitting an ICMP echo request packet addressed to a plurality of fixed segment GWs and confirming the source global IP address of the received ICMP echo response packet. . As for the transmission range of the ICMP echo request packet, for example, when the moving body is a train, the approximate position can be specified by the current time. Therefore, by transmitting to a fixed segment in the vicinity, unnecessary packet transmission can be prevented.

  Under this condition, the general user terminal 29 in the Internet X can access the client terminal 20A of the mobile unit 10. As an access procedure, the general user terminal 29 obtains a global destination IP address to the moving body at the present time from the location information server 30 and transmits a packet to the address, thereby enabling communication.

  In this embodiment, an ICMP echo request packet is transmitted from the location information server 30 to the global IP address 201.202.204.12 of the first GW 14A at regular intervals, and an ICMP echo response from the global IP of the first GW 14A is sent. By returning the packet, the position of the moving body is specified and the destination IP address is stored. However, in addition to the combination of the ICMP echo request and the ICMP echo response described in the present embodiment, any IP communication protocol having a similar request signal and response signal may be adopted. For example, the location information of the client terminal 20, that is, the location of the mobile object can be identified and communicated using the AP information registered in the location information server 30 by the mobile-side control unit 26.

  As described above, in the mobile communication network according to the present invention, the case where the first AP to the sixth AP 16A to 16F communicate with the transmission / reception unit 24 by a general wireless method has been described. However, the present invention is not limited to this. You may communicate by. For example, each of the first AP to the sixth AP transmits identification information unique to its own station AP by inserting it into a beacon radio wave at regular intervals, and the transmission / reception unit 24 periodically receives the beacon radio wave and transmits / receives it in advance. The belonging AP is determined according to the algorithm for selecting and determining the belonging AP defined as the function of the unit 24, and the identification information of the belonging access point is acquired. In this case, the operation of step 102 becomes unnecessary.

  Further, in the mobile communication network according to the present embodiment, the second AP 16B, the first AP 16A, and the third AP 16B in the first fixed segment 12A are not wired but may be wired depending on the situation of the location of the first AP 16A and the third AP 16B. And wireless combination. Similarly, the fifth AP 16E, the fourth AP 16D, and the sixth AP 16F in the second fixed segment 12B may be realized by a combination of wired and wireless depending on the situation of the arrangement location of the fourth AP 16D and the sixth AP 16F, even if they are not wireless.

  Further, in the mobile communication network according to the present embodiment, client terminals 20A, 20B... Exist in the user segment 10B and are connected to the mobile GW 22 wirelessly. Considering the number of terminals, the diversity of devices, and the variety of user services, the method is not limited to the method of wirelessly connecting to the mobile GW 22 and may be realized by a combination of wired and wireless. .

  Furthermore, in the mobile communication network according to the present embodiment, the user segment in the mobile 10 is considered in consideration of the type of mobile 10, the number of client terminals, the diversity of devices, the diversity of user services, and the like. 10B may be omitted. FIG. 4 shows a case where the client terminal 20A exists in the moving segment 10A and is connected to the moving side control unit 26. Since the client terminal 20A exists in the moving segment, its private IP address is assigned 192.168.1.245. This mobile communication network can operate in the same manner as the client terminal 20A plays the role of the mobile GW 22 in the above embodiment. For this reason, the client terminal 20 </ b> A sets 192.168.1.251, which is the shared IP address of the first GW 14 </ b> A and the second GW 14 </ b> B, as the default GW, and is connected to the ARP table 33.

  In the mobile communication network according to the present embodiment, the case where there is one mobile body has been described, but even a plurality of mobile bodies can operate in the same manner at the same time. Even a plurality of client terminals can operate in the same manner at the same time.

It is a conceptual diagram of the Example of the mobile communication network which concerns on this invention. In the mobile communication network according to the present embodiment, when transmitting a packet from the client terminal 20A in the mobile body to the Web server 28 connected to the Internet, the mobile terminal transmits the packet to the location information server connected to the Internet. It is a sequence flow which shows operation | movement in the case. It is a sequence flow which shows operation | movement in the case of transmitting a packet from the general user terminal 29 connected to the internet to the client terminal 20A in a mobile body in the mobile communication network which concerns on a present Example. It is a conceptual diagram of the other Example of the mobile communication network which concerns on this invention. It is a conceptual diagram of the network which comprises the conventional mobile IP technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile body 10A Moving segment 10B User segment 12A, 12B Fixed segment 14A, 14B 1st GW, 2nd GW
16A-16F 1st AP to 6th AP
17A, 17B ARP tables 18A, 18B First controller, second controllers 19A, 19B MAC address DB
20A, 20B Client terminal 21 MAC address DB
22 Mobile GW
23 ARP table 24 Transmission / reception unit 26 Movement side control unit 28 Web server 29 General user terminal 30 Location information server X Internet 33 ARP table

Claims (7)

A mobile communication network comprising a mobile segment existing in a mobile body and two or more fixed segments arranged on the ground, wherein the mobile segment and the two or more fixed segments are configured with the same address system. ,
Each of the two or more fixed segments includes a fixed gateway accessible to the Internet network, and at least one access point connected to the fixed gateway and capable of communicating with the mobile segment. The fixed segment side IP addresses of the fixed side gateways of the respective fixed segments are all set to be the same,
The mobile segment includes a mobile gateway accessible to one or more client terminals existing in the mobile body, and a transmission / reception unit connected to the mobile gateway and capable of communicating with the access point,
The mobile gateway uses the IP address of the default gateway as the IP address of the fixed gateway, recognizes the MAC address of the fixed gateway corresponding to the IP address of the fixed gateway, and uses the recognized MAC address as the IP address of the fixed gateway. A mobile communication network characterized in that it is used as a MAC address of a default gateway of a mobile gateway, thereby enabling the client terminal to access the Internet network via the fixed gateway. The mobile segment includes a MAC address database that stores at least a MAC address of the fixed side gateway and an IP address on the fixed segment side, and a fixed side gateway of the fixed segment to which the access point to which the transceiver can communicate belongs. A MAC address registration unit capable of registering a MAC address based on the MAC address database,
The mobile communication network according to claim 1, wherein the mobile gateway is configured to recognize a MAC address of the fixed gateway based on the MAC address registration unit. A mobile communication network comprising a mobile segment existing in a mobile body and two or more fixed segments arranged on the ground, wherein the mobile segment and the two or more fixed segments are configured with the same address system. ,
Each of the two or more fixed segments includes a fixed gateway that can access the Internet network, and at least one or more access points that are connected to the fixed gateway and can communicate with the mobile segment. The fixed segment side IP addresses of the fixed side gateways of each fixed segment are all set to be the same,
The mobile segment is accessible to one or more client terminals existing in the mobile body, and includes a transmission / reception unit capable of communicating with the access point,
The client terminal accessible to the transmission / reception unit sets the IP address of the default gateway as the IP address of the fixed gateway, recognizes the MAC address of the fixed gateway corresponding to the IP address of the fixed gateway, The recognized MAC address is used as a MAC address of a default gateway of a client terminal accessible to the transmission / reception unit, thereby enabling the client terminal to access the Internet network through the fixed gateway. Mobile communication network. The mobile segment includes a MAC address database that stores at least a MAC address of the fixed side gateway and an IP address on the fixed segment side, and a fixed side gateway of the fixed segment to which the access point to which the transceiver can communicate belongs. A MAC address registration unit capable of registering a MAC address based on the MAC address database,
4. The mobile communication network according to claim 3, wherein the client terminal accessible to the transmission / reception unit is configured to recognize a MAC address of the fixed gateway based on the MAC address registration unit.        The mobile communication network according to claim 1, wherein the access point is arranged along a predetermined movement path of the mobile body. Storing information on an access point with which the mobile unit can communicate or a fixed segment to which the mobile unit belongs, as a location information of the mobile unit, and further comprising a location information management unit connected to the Internet,
The transmission / reception unit transmits information about the recognized transmittable access point to the location information management unit,
6. The mobile communication network according to claim 1, wherein the position information management unit stores the position information of the mobile body based on the received information on the access point. A location information management unit for storing an IP address for communication access from the Internet network toward the mobile segment as information on the location of the mobile unit;
The location information management unit transmits a request signal for communication confirmation to a client terminal accessible to the mobile side gateway or the transmission / reception unit via the fixed side gateway and access point of the fixed segment to which the mobile body belongs,
When the mobile terminal or the client terminal accessible to the transmission / reception unit receives the request signal for the communication confirmation, it returns a response signal communicable to the location information management unit,
6. The position information management unit, upon receiving the response signal, stores an IP address for communication access from the Internet network toward the mobile segment based on the response signal. Any one of the mobile communication networks.

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