Communication system, mobile communication terminal and position managing apparatus

Abstract

A mobile node includes a plurality of transceivers, has a network conforming to network-based mobility as its home link and performs position registration to a positional managing apparatus and performs position registration to the position managing apparatus through a foreign network by position registration conforming to host-based mobility. In mobile node and position managing apparatus, a plurality of routes passing through the home link and the foreign link are established. Accordingly, when the mobile node has the plurality of transceivers, it can simultaneously connect to the home link and the foreign link through respective transceivers, to perform communication.

Claims

1. A terminal apparatus comprising: a processor; and transceiver circuitry, wherein the transceiver circuitry is configured to initiate a first communication route establishment procedure by transmitting control information requesting an establishment of a first communication route, the processor is configured to establish the first communication route over a first access system with a device in a communication carrier network, based on the first communication route establishment procedure, the transceiver circuitry is configured to initiate a second communication route establishment procedure by transmitting control information requesting an establishment of a second communication route, the processor is configured to establish the second communication route over a second access system with the device, based on the second communication route establishment procedure, the processor is configured to maintain simultaneously the first communication route and the second communication route, both of which are used for communications, using a first IP address, that are performed by the terminal apparatus, the first IP address being allocated to the terminal apparatus, and the transceiver circuitry is configured to perform the communications over either the first communication route or the second communication route or both.

2. A communication control method for a terminal apparatus, the communication control method comprising: initiating a first communication route establishment procedure by transmitting control information requesting an establishment of a first communication route; establishing the first communication route over a first access system with a device in a communication carrier network, based on the first communication route establishment procedure; initiating a second communication route establishment procedure by transmitting control information requesting an establishment of a second communication route; establishing the second communication route over a second access system with the device, based on the second communication route establishment procedure; maintaining simultaneously the first communication route and the second communication route, both of which are used for communications, using a first IP address, that are performed by the terminal apparatus, the first IP address being allocated to the terminal apparatus; and performing the communications over either the first communication route or the second communication route or both.

3. A core network comprising: first transceiver circuitry configured to connect to a first access system; and second transceiver circuitry configured to connect to a second access system, wherein the first transceiver circuitry is configured to: perform a first communication route establishment procedure for an establishment of a first communication route; and establish the first communication route over a first access system with a terminal apparatus, based on the first communication route establishment procedure, the second transceiver circuitry is configured to: perform a second communication route establishment procedure for an establishment of a second communication route; and establish the second communication route over a second access system with the terminal apparatus, based on the second communication route establishment procedure, the core network maintains simultaneously the first communication route and the second communication route, both of which are used for communications, using a first IP address, that are performed by the terminal apparatus, the first IP address being allocated to the terminal apparatus, and the core network performs the communications over either the first communication route or the second communication route or both.

4. A communication control method for a core network, the communication control method comprising: performing a first communication route establishment procedure for an establishment of a first communication route; establishing the first communication route over a first access system with a terminal apparatus, based on the first communication route establishment procedure; performing a second communication route establishment procedure for an establishment of a second communication route; establishing the second communication route over a second access system with the terminal apparatus, based on the second communication route establishment procedure; maintaining simultaneously the first communication route and the second communication route, both of which are used for communications, using a first IP address, that are performed by the terminal apparatus, the first IP address being allocated to the terminal apparatus; and performing the communications over either the first communication route or the second communication route or both.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 A diagram showing the outline of a communication system.

(2) FIG. 2 A diagram showing one exemplary configuration of a mobile node.

(3) FIG. 3 A diagram showing one example of the data structure of an address management table.

(4) FIG. 4 A diagram showing one exemplary configuration of a PMA.

(5) FIG. 5 A diagram showing one example of the data structure of an attachment node management table.

(6) FIG. 6 A diagram showing one exemplary configuration of a position managing apparatus.

(7) FIG. 7 A diagram showing one example of the data structure of a positional information management table.

(8) FIG. 8 A sequence diagram in a position registering process.

(9) FIG. 9 An operation flow chart showing the operation of a mobile node.

(10) FIG. 10 An operation flow chart showing the operation of a mobile node.

(11) FIG. 11 An operation flow chart showing the operation of a position managing apparatus.

(12) FIG. 12 A diagram showing the scheme of a communication system.

(13) FIG. 13 A sequence diagram showing packet forwarding.

(14) FIG. 14 A diagram showing one example of a packet format.

(15) FIG. 15 A diagram showing one example of a packet format.

(16) FIG. 16 An operation flow chart showing the operation of a mobile node.

(17) FIG. 17 An operation flow chart showing the operation of a position managing apparatus.

(18) FIG. 18 A diagram for illustrating a variational example in the embodiment.

(19) FIG. 19 A diagram for illustrating a variational example in the embodiment.

(20) FIG. 20 A diagram for illustrating a conventional communication system.

(21) FIG. 21 A diagram for illustrating a conventional communication system,

DESCRIPTION OF REFERENCE NUMERALS

(22) 10 access router (AR) 20 mobile node 200 processor 202 first transceiver 204 second transceiver 206 storage 2062 address management table 208 PMIPv6 processor 210 MIPv6 processor 212 packet transmitter 30 PMA 300 processor 302 wireless transceiver 304 wired transceiver 306 storage 3062 attachment node management table 308 PMIPv6 processor 310 packet forwarder 40 position managing apparatus (HA) 400 processor 402 PMIP network transceiver 404 foreign network transceiver 406 Storage 4062 positional information management table 408 PMIPv6 processor 410 MIPv6 processor 412 packet forwarder

BEST MODE FOR CARRYING OUT THE INVENTION

(23) Now, the best example of a packet communication system in the case to which the present invention is applied will be described using the drawings.

1. Configuration

1.1 Network Configuration

(24) To begin with, the packet communication system in the present exemplary embodiment is constructed of networks conforming to network-based mobility and host-based mobility, and has a configuration that can connect to a PMIP network as the home link and a foreign network as the foreign link at the same time, as shown in FIG. 1.

(25) Further, the position managing apparatus (Home Agent: HA) for performing positional management of mobile nodes in each network is comprised of a single apparatus. In the PMIP network as a network-based mobility network, a plurality of PMAs (Proxy Mobile Agents) serving as default routers for mobile nodes and forwarding packets to position managing apparatus are deployed. In the foreign network as a host-based mobility network, a plurality of ARs (Access Routers)serving as default routers and distributing addresses to be acquired at the connection points of mobile nodes are deployed.

(26) In the drawings, a PMA 30 is provided in the PMIP network and an AR 10 is provided in the foreign network. Further, in the PMIP network, an HA 40 is provided as the position managing apparatus. Connected to the foreign network is a communication device to be the opposite end from the mobile node.

(27) A mobile node 20 shown in FIG. 1 is assigned with “HoA(P1::MN1)” as its home address. It is also assigned with “CoA(P2::MN1)” as its care-of address when it connects to the foreign network.

(28) Here, for description convenience, FIG. 1 shows only one AR 10, mobile node 20 and PMA 30 as each device, but multiple devices may, of course, be deployed.

(29) Here, one example of the network-based mobility network may be a cellular network which a communication carrier that operates to connect cellular phones, a carrier's network for operating an ISP, or the like. Further, one example of the foreign network for supporting movement based on host-based mobility may be a WLAN, home network, or a carrier network operated by another carrier.

1.2 Mobile Node Configuration

(30) Next, the configuration of mobile node 20 will be described. Mobile node 20 is a mobile terminal that makes simultaneous connection to a plurality of network accesses such as a cellular mobile terminal, PDA, etc. having mobile node functionality conforming to PMIPv6, MIPv6 and MCoA. It also has the function of establishing simultaneous connection to its home link which is a network-based mobility network and a foreign link which is a host-based mobility network.

(31) Here, mobile node 20 includes, as shown in FIG. 2, a processor 200, a first transceiver 202, a second transceiver 204, a storage 206, a PMIPv6 processor 208, an MIPv6 processor 210 and a packet transmitter 212.

(32) Processor 200 is a functional part for controlling mobile node 20, or the functional part executing processes based on a predetermined program to transmit commands and data to diverse functional parts. For example, processor 200 is constructed of a CPU (Central Processing Unit) and the like.

(33) First transceiver 202 and second transceiver 204 are each connected to an external antenna, and transceivers for establishing wireless connection to a network. The transceivers perform transmission and reception of packets via respective networks. As the wireless accessing technique for first transceiver 202 and second transceiver 204 to achieve wireless connection herein, any technology such as a wireless access system used in wireless LANs, cellular networks, a short-distance wireless access system such as Bluetooth (registered trademark) etc., and the like can be used.

(34) Storage 206 is a functional part for storing various kinds of data and programs, in particular, includes an address management table 2062. Address management table 2062 is a table for storing default data for connection based on PMIPv6. It also stores the care-of address as connection information for connection to a foreign network based on MIPv6, the HA address and default router information.

(35) Here, FIG. 3 shows one example of the data configuration of address management table 2062. Herein, an address as positional information, a default router and a position managing apparatus are stored in a related manner. For example, for the home address (HoA) “P1::MN1”, “PMA 30” is associated as the default router for connection based on PMIPv6 and a care-of address (CoA)“P2::MN1” is associated to connect based on MIPv6. Further, for care-of address (CoA)“P2::MN1”, “AR 10” is stored as the default router and “HA 40” is stored as the position managing apparatus.

(36) Packet transceiver 212 selects either first transceiver 202 or second transceiver 204 based on address management table 2062 stored in storage 206 and sends out a packet therethrough. Further, it receives a received packet from each transceiver.

(37) MIPv6 processor 210 is a functional part for performing an MIPv6 process when connection from the PMIP network to the foreign network is implemented. Further, PMIPv6 processor 208 is a functional part for performing transmission and reception of an attachment request and reply when connection to the PMIP network is performed.

1.3 PMA Configuration

(38) Next, the configuration of a PMA 30 in the present embodiment will be described. PMA 30 is an apparatus constructed conforming to PMIPv6.

(39) As shown in FIG. 4 PMA 30 includes a processor 300, a wireless transceiver 302, a wired transceiver 304, a storage 306, a PMIPv6 processor 308 and a packet forwarder 310. Further, an external antenna for communications is connected to wireless transceiver 302.

(40) Processor 300 is a functional part for controlling PMA 30, or the functional part executing processes based on a predetermined program to transmit commands and data to diverse functional parts. For example, processor 300 is constructed of a CPU (Central Processing Unit) and the like.

(41) Wireless transceiver 302 is a transceiver for establishing wireless connection to mobile node 20 and performs transmission and reception of packets. As the wireless accessing technique for wireless connection, any of a wireless LAN, a wireless access system used in cellular networks and a short-distance wireless access system such as Bluetooth (registered trademark) etc., can be used.

(42) Wired transceiver 304 is a transceiver that is connected by wire to a router or a switch inside the PMIP network, and is a functional part for performing transmission and reception of packets. As the accessing technique for wired connection, widely used Ethernet (registered trademark) or the like can be used.

(43) Storage 306 is a functional part for storing various kinds of data and programs, in particular, includes an attachment node management table 3062. Attachment node management table 3062 stores attachment mobile nodes and their correspondent forwarding positions (addresses).

(44) Here, FIG. 5 shows one example of the data configuration of attachment node management table 3062. Herein, attachment nodes are stored in association with forwarding positions. For example, “mobile node 30” and the forwarding position of mobile node 30, “HoA(P1::MN1)” are stored in association with each other.

(45) The forwarding designation of nodes that have not been registered in attachment node management table 3062 are registered as “the others”. For example, in the case of FIG. 5, a packet of a node that has not been registered in attachment node management table 3062 will be forwarded to “HA 40”.

(46) PMIPv6 processor 308 is a functional part that notifies HA 40 of the identification information on mobile node 20 and the identification information on PMA 30. Further, the PMA registers into attachment node management table 3062 in storage 306 the fact that the mobile node has attached to itself. Further, the PMA makes a reply to the attachment request to the mobile node.

(47) With this configuration, the mobile node can register its position to HA 40 when the mobile node has attached to PMA 30. Further, it is possible to determine the delivery address of the packet addressed to the attached mobile node.

(48) Packet forwarder 310 is a functional part for forwarding packets based on attachment node management table 3062. For example, based on the attachment node management table 3062 shown in FIG. 5, a packet to mobile node 30 will be forwarded to the address of “HoA(P1::MN1)”.

1.4 HA Configuration

(49) Next, HA 40 in the present embodiment will be described. As shown in FIG. 6, HA 40 includes: a processor 400; a PMIP network transceiver 402 for connection to the PMIP network; a foreign network transceiver 404 for connection to a foreign network; a storage 406; a PMIPv6 processor 408; an MIPv6 processor 410; and a packet forwarder 412.

(50) Processor 400 is a functional part for controlling HA 40, or the functional part executing processes based on a predetermined program to transmit commands and data to diverse functional parts. For example, processor 400 is constructed of a CPU (Central Processing Unit) and the like.

(51) PMIP network transceiver 402 or foreign network transceiver 404 is a transceiver that is connected by wire to a router or a switch and performs transmission and reception of packets. As the accessing technique for wired connection, any of the technologies that are widely used in networks, such as Ethernet (registered trademark) and the like can be used.

(52) Storage 406 is a functional part for storing various kinds of data and programs, in particular, includes a positional information management table 4062. Positional information management table 4062 stores a mobile node in association with the position (address) of the correspondent mobile node. Here, the MIPv6 positional information contains identification information on a mobile node and a care-of address gained on the foreign network to which the mobile node connects.

(53) FIG. 7 shows one example of the data configuration of positional information management table 4062. As shown in FIG. 7, positional information management table 4062 stores a mobile node and the position (address) of the correspondent mobile node. For example, the position of mobile node 20 (HoA(P1::MN1)) is stored as to be PMA 30 and CoA(P2::MN1).

(54) PMIPv6 processor 408 is a functional part that, when receiving a position registration signal from PMA 30, registers the positional information into positional information management table 4062 and transmits a reply to PMA 30. Further, MIPv6 processor 410 is a functional part that, when receiving a position registration signal from mobile node 20, registers the position into positional information management table 4062 and transmits a reply to mobile node 20.

(55) The packet forwarder is a functional part for forwarding a packet based on positional information management table 4062 stored in storage 406. This controls packet forwarding via PMIP network transceiver 402 or foreign network transceiver 404.

2. Processing Flow

2.1 Position Registering Procedure

2.1 System Flow

(56) Next, the updating processes of the positional information in mobile node 20, PMA 30, AR 10 and HA 40 in the network shown in FIG. 1 will be described using the drawings.

(57) To begin with, the position registering procedure of mobile node 20 will be described based on the sequence diagram in FIG. 8. When detection connection to the PMIP network as a network-based mobility network, mobile node 20 makes an attachment request (procedure (a) in FIG. 8).

(58) For example, mobile node 20, when it is started to operate, or power is turned on, sends an Association Request message for RRC (Radio Resource control) to PMA 30 to which it is going to attach, to make an attachment request. At this point, mobile node 20 receives announcing information from neighboring PMAs and selects PMA 30 based on the result of performing cell search. Specifically, the mobile node notifies the identification information for itself to be identified, such as the global IP address, MAC address or UE-ID defined by specifications such as 3GPP TS23.003V5.2.0, by the Association Request message so as to make an attachment request.

(59) In PMA 30, wireless transceiver 302 receives the Association Request and registers the identification information of mobile node 20 and the fact that mobile node 20 has attached to PMA 30, into attachment node management table 3062 of storage 306.

(60) PMA 30 solves HA 40 at the destination to register based on the attachment request from mobile node 20 and transmits a position registering request to HA 40 (procedure (b) in FIG. 8). The method of solving HA 40 may be acquired from the apparatus for managing the correspondence between mobile node 20 and HA 40, such as an AAA server etc., to which PMA 30 is connected, for example, or it is possible to solve it by storing the receiver management table that previously holds management information of the correspondence between mobile node 20 and HA 40 into storage 306, in advance.

(61) Specifically, PMA 30 notifies the identification information for identifying mobile node 20, such as the global IP address, MAC address or UE-ID, and an IP address for identifying PMA 30 that can be routed inside the PMIP network, as the positional information.

(62) HA 40 receives the position registering request from PMA 30, and registers the identification information of mobile node 20 associated to its positional information into positional information management table 4062. The reply message includes the global IP address to be assigned to mobile node 20, or network prefix information of the global IP address to be assigned to the mobile node.

(63) When HA 40 registers the information on mobile node 20 into positional information management table 4062, then it transmits a position registration reply to PMA 30 (procedure (c) in FIG. 8).

(64) PMA 30, as receiving the reply from HA 40, registers into attachment node management table 3062 the forwarding destination of the packet transmitted from mobile node 20 to be the HA and so that a packet addressed to the mobile node will be delivered to the mobile node.

(65) PMA 30 makes a response to the attachment request from mobile node 20 using RCC Association Response message or the like to the mobile node (procedure (d) in FIG. 8). The reply to the attachment request includes identification information such as the IP address or MAC address of PMA 30 so that mobile node 20 can set PMA 30 as the default router.

(66) Mobile node 20 receives the attachment reply from first transceiver 202 and registers PMA 30 as the attachment destination into address management table 2062. This identification information on PMA. 30 does not need to be identical with the identification information on PMA 30 registered in HA 40. For example, the IP address notified to HA 40 is the IP address to be used for routing within the PMIP network, whereas the IP address notified to the mobile node is the IP address which the mobile node identifies as the default router.

(67) As above, mobile node 20 performs connection to the PMIP network, in accordance with the procedures defined by PMIPv6. Further, a forwarding route is established between PMA 30 and HA 40, so that mobile node 20 can perform communications by way of the forwarding route established in the PMIP network.

(68) Next, mobile node 20, while keeping connection to the PMIP network, performs connection to the foreign network using another transceiver.

(69) Mobile node 20 makes another transceiver or second transceiver 204 receive announcing information from the access router (AR 10) on the network connected to it, to detect connection to the foreign network (procedure (e) in FIG. 8). Here, the announcing information transmitted from AR 10 is IPv6 router announcing information or the like, including information on the network prefix of the connected network in addition to the MAC address and IP address of the access router.

(70) Mobile node 20 generates its care-of address based on the network prefix information of the connected network of the received announcing information and transmits a position registering request to HA 40 (procedure (f) in FIG. 8). The position registering request to be transmitted should include identification information of the mobile node such as the home address, MAC address or UE-ID etc., and the care-of address to be the positional information.

(71) HA 40 receives the position registering request from mobile node 20 and registers it into positional information management table 4062. Registered into positional information management table 4062 is identification information of the mobile node such as the home address, MAC address or UE-ID etc., of mobile node 20 in association with the positional information, i.e., the care-of address. As the aforementioned positional information management table 4062, the same one that is used at the time of position registration in the PMIP network may be used. As a result, HA 40 can handle mobile node 20 having a single home address by managing a plurality of positional information at the same time, the care-of address as the positional information in the foreign network and PMA 30 as the positional information in the home link or the PMIP network.

(72) HA 40, after registration into positional information management table 4062, transmits a position registration reply to mobile node 20 (procedure (g) in FIG. 8).

(73) Mobile node 20 receives the position registration reply from HA 40 and manages the care-of address or home address and the address of HA 40 as the position managing apparatus, with address management table 2062.

(74) In the example where conventional PMIPv6 and MIPv6 are combined, in HA 40, when a position registering request based on MIPv6 as shown in procedure (f) in FIG. 8 is received in the state where PMIPv registration is being performed, the positional information of PMIPv6 as the home link is deleted and the positional registration based on the MIPv6 request is performed. Specifically, when the position registering request by procedure (f) in FIG. 8 is received, the positional information of the PMIP network in positional information management table 4062 is deleted and the positional information based on MIPv6 is registered.

(75) In the HA 40 in the present embodiment, the positional information of the PMIP network and the positional information based on the MIPv6 are registered simultaneously in the positional information management table.

(76) That is, it is the conventional practice that when HA 40 that manages connection to the home link as the PMIP network receives a connection request from the foreign link, the HA cuts connection to the home link and permits connection to the foreign link. However, the HA 40 of the present embodiment manages both the connection information without cutting connection to the home link.

(77) Also, in the example where conventional PMIPv6 and MIPv6 are combined, when position registration is performed in mobile node 20 based on MIPv6 by means of another transceiver in the state where the mobile node is being connected to the PMIP network, the information on connection to the PMIP network is deleted at the time of position registering, then position registration is performed from the foreign network based on MIPv6. Specifically, when the information on the attachment to the PMIP network is deleted in address management table 2062, and a position registering request is transmitted to HA 40. However, in the present embodiment, mobile node 20 holds the position registration information for both the PMIP network and the foreign network at the same time. That is, both the information of attachment to the PMIP network and the information of registration to HA 40 using the care-of address obtained through the foreign network will be registered at the same time.

(78) Accordingly, mobile node 20 connected to the packet communication system in the present embodiment will perform positional registration from the foreign link without cutting off the connection with the home link to manage both connection information.

(79) In the state where mobile node 20 is being connected to the PMIP network, HA 40 which has received the positional registration to the foreign network can keep both the positional information on the home link and on the foreign link. However, in order to permit disconnection from the home link as in the conventional manner when a request for connection to the foreign link is made, information that indicates either disconnection or simultaneous connection may be newly included to the position registration information in the foreign link, whereby it is possible for HA 40 to determine whether HA 40 manages a plurality of positional information for the mobile node or whether it deletes the holding information and performs new registration, in accordance with the request from mobile node 20.

(80) Specifically, the position registering request in procedure (f) in FIG. 8 is added with a flag and is transmitted. Here, the flag is to be used to determine whether the connection information in the home link should be deleted.

(81) Similarly, in the case where, while the mobile node is being connected from a foreign link based on MIPv6, it makes a request for attachment to the PMIP network to perform position registering to HA 40 through PMA 30, HA 40 can perform a plurality of position registration in accordance with the request from PMA 30 as stated above. However, it is also possible to cut off the connection to the foreign link and establish connection to the home link as performed conventionally.

(82) Accordingly, mobile node 20 transmits an attachment request including the information that shows either cutoff or simultaneous connection, to PMA 30. Further, PMA 30 transmits a position registering request including the information indicating whether the cutoff has been done or simultaneous connection is being established, to HA 40. HA 40 is able to determine whether it manages a plurality of positional information for mobile node 20 or whether it deletes the holding information and performs new registration, in accordance with the request from mobile node 20.

(83) Specifically, the attachment request in procedure (a) in FIG. 8 is added with a flag and is transmitted. This flag is used to determine whether the connection information on the foreign network should be deleted. In procedure (b) in FIG. 8, PMA 30 adds the flag included in the attachment request to the position registering request to be transmitted to HA 40 and sends it.

(84) Though the present embodiment was described taking an example in which connection to the foreign network is achieved after connection with the PMIP network, it goes without saying that connection to the PMIP network may be achieved after connection with the foreign network.

2.1.2 Mobile Node's Processing Flow

(85) Next, the operation of mobile node 20 in the position registering procedure will be described using an operation flow. First, FIGS. 9 and 10 are charts for illustrating the process related to position registering at mobile node 20.

(86) When mobile node 20 detects the fact that it has moved from one network to another (Step S102; Yes), it is checked whether the packet received at the time of detection is one based on PMIPv6 or one based on MIPv6 (Step S104).

(87) Herein, when it is determined that the received packet is one that is based on PMIPv6 (Step S106, Yes), it is checked whether updating should be done by registering a plurality of positional information (Step S108).

(88) Here, if updating is performed by registering the plurality of positional information (Step S108; Yes), a flag that indicates that updating needs to be done by the plurality of registration is added (Step S110). Then, an attachment request to the PMIP network is transmitted to PMA 30 (Step S112).

(89) On the other hand, when it is determined that the packet detected at the time of detection of movement is one that is not based on PMIPv6 (Step S106; No), it is determined that the packet is one based on MIPv6. Further, if updating is performed by registering the plurality of positional information (Step S120; Yes), a flag that indicates that updating needs to be done by the plurality of registration is added (Step S122). Then, a position registering request for the position in the foreign network is transmitted to HA 40 (Step S124).

(90) Subsequently, it is checked whether there has been reception of an attachment reply from the PMIP network or PMA 30 (Step S202) or whether there has been reception of a reply based on MIPv6 from HA 30 (Step S204).

(91) Herein, when reception of an attachment reply has been received (Step S202; Yes/procedure (d) in FIG. 8) or when reception of a position registration reply has been received (Step S202; No.fwdarw.Step S204; Yes/procedure (g) in FIG. 8), it is checked whether the received attachment reply reception or position registration reply reception includes the flag so as to determine whether a plurality of positional information (addresses) are registered (Step S206). Here, if it has been determined that updating is performed by registering the plurality of positional information (addresses) thanks to inclusion of the flag (Step S206; Yes), positional information (address) is added to address management table 2062. On the other hand, if it has been determined that updating is not performed by registering the plurality of positional information (addresses) thanks to non-inclusion of the flag (Step S206; No), positional information (address) in address management table 2062 is updated and stored.

2.1.3 HA's Processing Flow

(92) Next, the operation of HA 40 when a mobile node is registered will be described using an operation flow in FIG. 11.

(93) First, HA 40 receives a position registering request (Step S302). Here, there are cases in which the position registering request is demanded from PMA 30 (procedure (b) in FIG. 8) and in which it is demanded from mobile node 20 (procedure (f) in FIG. 8).

(94) Next, HA 40 determines whether it is necessary to register a plurality of positional information that is demanded to be registered (Step S304). That is, it is determined whether there is the predetermined flag in the position registering request signal. If there is the flag, it is determined that the plurality of positional information should be registered, so that the position is additionally registered into positional information management table 4062. (Step S304; Yes.fwdarw.Step S306). On the other hand, if there is no flag in the position registering request signal, the positional information stored in positional information management table 4062 is updated (Step S304; No.fwdarw.Step S308).

(95) When completing position registering, HA 40 transmits a position registration reply (Step S310). Here, the position registration reply is transmitted to PMA 30 (procedure (c) in FIG. 8) and mobile node 20 (procedure (g) in FIG. 8).

2.2 Packet Forwarding Procedure

2.2.1 System Flow

(96) Next, communication between mobile node 20 connected to the PMIP network and a foreign network and a communication terminal 50 connected to the foreign network will be described using the drawings. FIG. 12 is a diagram showing the scheme of a mobile communication system. As described heretofore, mobile node 20 includes a plurality of transceivers, one connecting to the PMIP network and the other to the foreign link. The PMIP network is the home link for mobile node 20, and movement of mobile node 20 changing PMAs inside PMIP network is done based on PMIPv6. On the other hand, the node is connected to the foreign network by the other transceiver, and movement of the node by changing ARs in the foreign network is done based on MIPv6. Position registering for simultaneous use to both is realized in the method described above.

(97) First, the sequence diagram in FIG. 13 is a chart for illustrating the overall flow of the packet forwarding procedure. FIG. 14 is a diagram schematically showing how packets are forwarded.

(98) To begin with, a forwarding route has been established between PMA 30 and HA 40. This forwarding route is a forwarding path by way of the PMIP network. Established further between HA 40 and mobile node 20 is a forwarding route by way of AR 10. This forwarding route is a forwarding path by way of the foreign network.

(99) Though in the present embodiment, the process of a case in which a packet is transmitted from communication terminal 50 to mobile node 20 and a reply to it is made will be described, it is of course possible to similarly handle the case in which a packet is transmitted from mobile node 20 to communication terminal 50.

Packet Forwarding Through PMIP Network

(100) First, a case where a packet is forwarded by way of the PMIP network will be described. When a packet is transmitted from communication terminal 50 to mobile node 20, the packet is transmitted to HA 40 (procedure (a) in FIG. 13). At this point, the sender in the IP header of the packet is “communication terminal 50” and the receiver is “mobile node 20” (FIG. 14(a)).

(101) In this case, HA 40 is the point of connection between the PMIP network and the foreign network, and is the only gateway router that announces the routing information on the home network prefix of the mobile node. Specifically, HA 40 announces the routing information to the foreign network so that any packet addressed to the home prefix of the mobile node can be delivered to itself, and any packet addressed from the communication terminal connected to the foreign network to the mobile node is delivered to HA 40.

(102) HA 40 determines whether the packet is forwarded by way of the PMIP network or by way of the foreign network, and forwards the packet. Herein, if the packet is assumed to be forwarded through the PMIP network, the packet is forwarded to PMA 30 (procedure (b) in FIG. 13). At this point, the sender in the IP header of the forwarded packet is “HA 40” and the receiver is “PMA 30” (FIG. 14(b)). The packet data shown in FIG. 14(a) is stored as the payload. Then PMA 30 transmits the packet received from HA 40 to the receiver or mobile node 20 (procedure (c) in FIG. 13).

(103) Next, when a packet is transmitted from mobile node 20 to communication terminal 50, the packet is transmitted to PMA 30 first (procedure (d) in FIG. 13). At this point, the sender in the IP header of the transmitted packet is “mobile node 20” and the receiver is “communication terminal 50” (FIG. 14(c)).

(104) Subsequently, PMA 30 forwards the packet data received from mobile node 20 to HA 40 (procedure (e) in FIG. 13). At this point, the sender in the IP header of the forwarded packet is “PMA 30” and the receiver is “HA 40” (FIG. 14(d)). The packet data shown in FIG. 14(c) is stored as the payload. Then HA 40 transmits the received packet to communication terminal 50 (procedure (f) in FIG. 13).

Packet Forwarding Through Foreign Network

(105) Next, a case where a packet is forwarded by way of a foreign network will be described. When a packet is transmitted from communication terminal 50 to mobile node 20, the packet is transmitted to HA 40 (procedure (g) in FIG. 13). At this point, the sender in the IP header of the packet is “communication terminal 50” and the receiver is “mobile node 20” (FIG. 15(a)).

(106) Then, HA 40 determines whether the packet is delivered by way of the PMIP network or by way of the foreign network, and forwards the packet. Herein, if the packet is assumed to be forwarded through the foreign network, the packet is transmitted to mobile node 20 by way of AR 10 (procedure (h) in FIG. 13). At this point, the sender in the IP header of the transmitted packet is “HA 40” and the receiver is “mobile node 20”. Here, a care-of address (CoA) is set for mobile node 20.

(107) Next, when a packet is transmitted from mobile node 20 to communication terminal 50, the packet is transmitted to HA 40 first by way of AR 10 (procedure (i) in FIG. 13). At this point, the sender in the IP header of the transmitted packet is “mobile node 20” and the receiver is “communication terminal 50” (FIG. 15(c)), but when it is sent to HA 40, the original IP packet is stored as the payload. That is, the packet is transmitted by setting the care-of address (CoA) of “mobile node 20” as the sender and HA 40 as the receiver. Then, HA 40 transmits the received packet to communication terminal 50 (procedure (j) in FIG. 13).

2.2.2 Mobile Node's Processing Flow

(108) Next, the operation of mobile node 20 in the packet forwarding procedure will be described using an operation flow. FIG. 16 is a chart for illustrating the process when a packet in mobile node 20 is transmitted.

(109) First, in mobile node 20, packet transmitter 212 creates a transmission packet (Step S402). Here, processor 200 checks the positional information stored in address management table 2062 (Step S404). In this case, when a plurality of positional information have been registered in address management table 2062 (Step S406; Yes), one transmission route is selected based on the positional information among them (Step S408).

(110) Then, a transmission route is determined from the selected transmission route or one transmission route defined as the positional information (Step S406; No)(Step S410). At this point, if transmission is carried out based on MIPv6 (Step S412; Yes), the packet is subjected to an MIPv6 process and then transmitted (Step S414). As the method for determining a transmission route at Step S410, a method of determining it using the routing protocol based on prefixes can be considered as an example.

2.2.3 HA's Processing Flow

(111) Next, the operation of HA 40 in the packet forwarding procedure will be described using an operation flow. FIG. 17 is a chart for illustrating the process when a packet is forwarded in HA 40.

(112) First, the packet is received by PMIP network transceiver 402 or foreign network transceiver 404 of HA 40 (Step S502). At this point, processor 400 determines whether the receiver of the received packet is addressed to a mobile node that the HA 40 manages (Step S504).

(113) If the packet is addressed to a mobile node that the HA 40 manages (Step S504; Yes), it checks the position of mobile node 20 (Step S506). At this point, if a plurality of positional information on mobile node 20 have been registered in positional information management table 4062 (Step S508; Yes), the forwarding route is selected based on one of the positional information (Step S510). Then, the HA determines a forwarding route (Step S512) based on the selected forwarding route or the one forwarding route defined as the positional information (Step S508; No) so as to forward the packet (Step S514). As the method for determining a transmission route at Step S410, a method of determining it using the routing protocol in the network can be considered as an example.

(114) As described heretofore, according to the present embodiment, mobile node 20 includes a plurality of transceivers so that it is possible to connect to the PMIP network as the home link through one transceiver and connect to a foreign network through the other transceiver at the same time. For the identifier of a single mobile node 20, HA 40 manages PMA 30 as its positional information on the PMIP network, and at the same time, manages its care-of address on the foreign network as the foreign network positional information.

(115) As a result, it is possible to establish a plurality of communication routes for a mobile node, hence select and use them depending on the preferences of the communication terminal at the communication partner side, communication data and the like.

3. Application Example

(116) Application of the present invention enables construction of a large-scale PMIP network operated by a carrier or the like as its home link while permitting mobile node 20 to connect the carrier network and a WLAN as a hot spot or the like at the same time. Further, the mobile node can perform communications using a single IP address in both networks. As a result, it is possible for the carrier, for example to achieve control such that an application that the carrier wants to be communicated through its own PMIP network is communicated by way of the PMIP network while an application that is regarded to be able to achieve a higher throughput if it is distributed through access networks such as WLAN etc., is entrusted to communication by way of a foreign network.

(117) For example, as shown in FIG. 18, communication between mobile node 1 and mobile node 2 connected to the PMIP network can be performed within the PMIP network using the transmission route between the HA and PMA 1 and the transmission route between the HA and PMA 2 while communication between a communication terminal and mobile node 1 connected to the foreign network can be realized through the foreign network using the transmission route designated by the care-of address which is used by the HA and mobile node 1 to connect to the foreign network. This enables an application such as voice communication between the subscribers of the carrier that operates the PMIP network to be executed by performing communication through the PMIP network, and a case when mobile node 1 acquires contents from WEB servers connected to the foreign network by FTP or HTTP access, to be achieved by performing communication by way of a foreign network.

(118) Further, it is possible to achieve seamless handover by realizing multiple connection at the same time. The conventional handover procedure in PMIP and MIPv6 is performed by switching one connection to another. In contrast, application of the present invention enables a mobile node to realize simultaneous connection as shown in FIG. 19, whereby it is possible to achieve handover in a seamless manner by only selecting the communication route of communication data after establishment of the connecting procedure. That is, it was conventionally necessary to implement mobile detection, terminal authentication and the like in addition to position registration and establishment of a transmission route as shown in the sequence when handover is carried out. However, application of the present invention, in a condition that a plurality of them are completed, makes it possible to achieve handover by updating only the information for selection of a transmission route of preferences and the like between the HA and the mobile node.