Router device, datagram transfer method and communication system realizing handoff control for mobile terminals

• US 20020191562A1
• Filed: 07/26/2002
• Published: 12/19/2002
• Est. Priority Date: 05/12/1997
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Matsuzawa, Shigeo, Tsunoda, Keiji, Moriya, Osamu, Okamoto, Toshio, Kato, Noriyasu, Kumaki, Yoshinari
• Granted Patent: US 7,151,758 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 2012/5607 Radio
• CPC Class Codes: H04L 2012/562 Routing
• CPC Class Codes: H04L 2012/563 Signalling, e.g. protocols, reference model
• CPC Class Codes: H04L 2012/5667 IP over ATM
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/083 wherein at least one of the access points is a moving node
• CPC Class Codes: H04W 40/18 based on predicted events
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A mobile supporting router device for realizing the handoff control associated with the moving in high speed is forms by at least one first interface connected with radio base stations, each capable of accommodating at least one mobile terminal; at least one second interface connected with a wire network; an information exchanging unit for exchanging a routing protocol on a network layer, through the second interface; a memory unit for storing information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit; a transfer unit for transferring datagram through the first interface according to the information regarding the routing on the network layer stored in the memory unit; a moving detection unit for detecting a moving of the mobile terminal among the radio base stations; and an information updating unit for updating the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit.

Claims

1. A router device, comprising:

at least one first interface connected with a plurality of radio base stations, each radio base station being capable of accommodating at least one mobile terminal;

at least one second interface connected with a network;

an information exchanging unit for exchanging a routing protocol on a network layer, through the second interface;

a memory unit for storing information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit;

a transfer unit for transferring datagram through the first interface according to the information regarding the routing on the network layer stored in the memory unit;

a moving detection unit for detecting a moving of the mobile terminal among the radio base stations; and

an information updating unit for updating the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit.

2. The router device of claim 1, wherein the information regarding the routing on the network layer indicates a correspondence between a destination network layer address of the datagram and a virtual connection to which the datagram should be transmitted.

3. The router device of claim 1, wherein the information regarding the routing on the network layer indicates a correspondence between a destination network layer address of the datagram and an output interface from which the datagram should be transmitted.

4. The router device of claim 1, wherein the transfer unit transfers the datagram through the first interface according to another information regarding a switching on a lower layer of the network layer for enabling datagram transfer along the routing on the network layer when a prescribed condition for the switching on the lower layer is satisfied.

5. The router device of claim 4, further comprising:

another memory unit for storing said another information regarding the switching on the lower layer of the network layer,

wherein the information updating unit also updates said another information regarding the switching on the lower layer of the network layer stored in said another memory unit when the moving of the mobile terminal is detected by the moving detection unit.

6. The router device of claim 4, further comprising:

another memory unit for storing a correspondence between a first virtual connection for connecting the first interface and a radio base station of a currently located site of the mobile terminal and a second virtual connection different from the first virtual connection, as said another information regarding the switching on the lower layer of the network layer;

wherein when the the moving of the mobile terminal corresponding to the first virtual connection is detected by the moving detection unit, the information updating unit also updates said another information regarding the switching on the lower layer of the network layer stored in said another memory unit, by obtaining a third virtual connection for connecting the first interface and a radio base station of a visited site of the mobile terminal and storing a correspondence between the third virtual connection and the second virtual connection in said another memory unit, while updating the information regarding the routing on the network layer by storing a network layer address of the mobile terminal after the moving and the third virtual connection in the memory unit.

7. The router device of claim 4, further comprising:

another memory unit for storing a correspondence between a first virtual connection for connecting the first interface and a radio base station of a currently located site of the mobile terminal and a second virtual connection different from the first virtual connection, as said another information regarding the switching on the lower layer of the network layer;

wherein when the the moving of the mobile terminal corresponding to the first virtual connection is detected by the moving detection unit, the information updating unit updates the information regarding the routing on the network layer by identifying a correspondence between a network layer address of the mobile terminal and a third virtual connection for connecting the first interface and a radio base station of a visited site of the mobile terminal according to message exchange with the mobile terminal or the radio base station of the visited site of the mobile terminal, and by storing the identified correspondence in the memory unit, while also updating said another information regarding the switching on the lower layer of the network layer stored in said another memory unit by storing a correspondence between the third virtual connection and the second virtual connection in said another memory unit.

8. The router device of claim 4, further comprising:

a switching unit for switching transfer of the datagram by the transfer unit between datagram transfer according to the information regarding the routing on the network layer and datagram transfer according to said another information regarding the switching on the lower layer of the network layer.

9. The router device of claim 1, wherein the information updating unit updates the information regarding the routing on the network layer such that the datagram destined to the mobile terminal is transmitted to both a radio base station of an originally located site of the mobile terminal and a radio base station of a visited site of the mobile terminal.

10. The router device of claim 1, further comprising:

a switching unit for switching transmission of the datagram by the transfer unit between datagram transmission to a radio base station of a visited site of the mobile terminal and datagram transmission to both a radio base station of an originally located site of the mobile terminal and a radio base station of a visited site of the mobile terminal;

wherein when the datagram transmission to both a radio base station of an originally located site of the mobile terminal and a radio base station of a visited site of the mobile terminal is to be used, the information updating unit updates the information regarding the routing on the network layer such that the datagram destined to the mobile terminal is transmitted to both a radio base station of an originally located site of the mobile terminal and a radio base station of a visited site of the mobile terminal.

11. The router device of claim 1, further comprising:

a switching unit for switching transmission of the datagram by the transfer unit during an updating processing by the information updating unit between a mode for continuing datagram transmission to a radio base station of an originally located site of the mobile terminal and a mode for stopping datagram transmission to a radio base station of an originally located site of the mobile terminal, according to a communication quality required for transfer of the datagram.

12. The router device of claim 1, further comprising:

a move over detection unit for detecting a move over of mobile terminal to a radio base station connected with another router device; and

a control unit for updating the information regarding the routing on the network layer such that datagram destined to the mobile terminal is transferred to said another router device, and transmitting a message for updating the information regarding the routing on the network layer in said another router device such that said another router device transfers the datagram to the mobile terminal, when the move over detection unit detects the move over of the mobile terminal.

13. The router device of claim 1, further comprising:

a move over detection unit for detecting a move over of mobile terminal to a radio base station connected with another router device; and

a control unit for updating the information regarding the routing on the network layer such that datagram destined to the mobile terminal is transferred to a first virtual connection to said another router device which is dedicated for the mobile terminal, and exchanging messages with said another router device such that said another router device can carry out a switching on a lower layer of the network layer between the first virtual connection and a second virtual connection from said another router to a radio base station of a visited site of the mobile terminal which is dedicated to the mobile terminal, when the move over detection unit detects the move over of the mobile terminal.

17. The datagram transfer method of claim 16, wherein the correspondence is stored such that the virtual connection to which datagram destined to the network layer address should be transmitted can be identified from the base station identifier.

19. The communication system of claim 18, wherein each radio base station has:

a connection unit for connecting each radio base station to a mobile communication network; and

a distribution unit for distributing data from the mobile terminal either to the virtual connection to the router device or the mobile communication network according to information indicating a communication protocol which is contained in a message from the mobile terminal.

20. The communication system of claim 18, wherein each radio base station has:

a transfer unit for transferring control information transmitted from the mobile terminal through a radio channel to a virtual connection for broadcast toward the router device.

21. The communication system of claim 18, wherein each radio base station has:

a notification unit for transmitting a notification information using different radio channels for different communication protocols to which messages to the mobile terminal obey; and

wherein the mobile terminal has a reception unit for receiving the notification information of a specific radio channel corresponding to a specific communication protocol normally, and start receiving the notification information of a different radio channel corresponding to a different communication protocol at a time of starting communications using the different communication protocol.

14. A router device, comprising:

at least one first interface connected with a plurality of radio base stations, each radio base station being capable of accommodating at least one mobile terminal;

at least one second interface connected with a network;

an information exchanging unit for exchanging a routing protocol on a network layer, through the second interface;

a memory unit for storing information regarding a routing on the network layer based on the routing protocol exchanged by the information exchanging unit;

a transfer unit for transferring datagram through the first interface according to another information regarding a switching on a lower layer of the network layer for enabling datagram transfer along the routing on the network layer;

a moving detection unit for detecting a moving of the mobile terminal among the radio base stations; and

an information updating unit for updating the information regarding the routing on the network layer stored in the memory unit when the moving of the mobile terminal is detected by the moving detection unit.

15. A router device, comprising:

a memory unit for storing information regarding a routing on a network layer;

a transfer unit for transferring datagram to a mobile terminal accommodated in a radio base station to which the router device is connected, according to the information regarding the routing on the network layer;

an address allocation unit for allocating a network layer address to the mobile terminal located within an area managed by the router device;

a moving detection unit for detecting a moving of the mobile terminal out from the area managed by the router device;

an updating unit for updating the information regarding the routing on the network layer when the moving is detected by the moving detection unit; and

an address release unit for releasing the network layer address when the moving is detected by the moving detection unit.

16. A datagram transfer method, comprising the steps of:

storing a mobile terminal identifier uniquely assigned to a mobile terminal, a network layer address allocated to the mobile terminal, and a correspondence between the network layer address allocated to the mobile terminal and a virtual connection to which datagram destined to the network layer address should be transmitted;

receiving a handoff request containing the mobile terminal identifier and a base station identifier of a radio base station of a visited site of the mobile terminal, indicating a moving of the mobile terminal between radio base stations;

acquiring a virtual connection to the radio base station of the visited site of the mobile terminal indicated by the handoff request, and obtaining the network layer address corresponding to the mobile terminal indicated by the handoff request according to the first correspondence;

updating the correspondence so as to set the obtained network layer address in correspondence to the acquired virtual connection;

transmitting a radio channel allocation request containing the mobile terminal identifier of the mobile terminal and a virtual connection identifier of the acquired virtual connection, to the radio base station of the visited site of the mobile terminal; and

transferring datagram according to the updated correspondence or information regarding a switching on a lower layer of a network layer for enabling datagram transfer according to the updated correspondence, upon receiving the datagram.

18. A communication system, comprising:

at least one mobile terminal;

a plurality of radio base stations; and

at least one router device having;

a memory unit for storing a first correspondence between a mobile terminal identifier uniquely assigned to the mobile terminal and a network layer address allocated to the mobile terminal, and a second correspondence between the network layer address and a virtual connection to which datagram destined to the network layer address should be transmitted;

a reception unit for receiving a handoff request containing the mobile terminal identifier and a base station identifier of a radio base station of a visited site of the mobile terminal, indicating a moving of the mobile terminal between radio base stations;

an updating unit for acquiring a virtual connection to the radio base station of the visited site of the mobile terminal indicated by the handoff request, obtaining the network layer address corresponding to the mobile terminal indicated by the handoff request according to the first correspondence, and updating the second correspondence so as to set the obtained network layer address in correspondence to the acquired virtual connection; and

a transmission unit for transmitting a radio channel allocation request containing the mobile terminal identifier of the mobile terminal and a virtual connection identifier of the acquired virtual connection, to the radio base station of the visited site of the mobile terminal;

wherein the radio base station of the visited site of the mobile terminal has;

a memory unit for storing a third correspondence between a virtual connection from the router device and a radio channel to which datagram received through the virtual connection from the router device should be transmitted; and

a setting unit for receiving the radio channel allocation request from the router device and setting a correspondence between a radio channel for the mobile terminal indicated by the radio channel allocation request and the acquired virtual connection indicated by the radio channel allocation request as the third correspondence.

22. A communication system, comprising:

at least one mobile terminal;

a plurality of radio base stations;

at least one router device having;

a memory unit for storing information regarding a routing on a network layer;

a transfer unit for transferring datagram to a mobile terminal accommodated in a radio base station with which the router device is connected, according to the information regarding the routing on the network layer;

an inter-router moving detection unit for detecting an inter-router moving of the mobile terminal between the router device and another router device; and

an updating unit for updating the information regarding the routing on the network layer when the inter-router moving is detected by the Inter-router moving detection unit; and

an address allocation module having;

an inter-network moving detection unit for detecting an inter-network moving of the mobile terminal between networks corresponding to prescribed network layer address allocation ranges;

a release unit for releasing a network layer address allocated to the mobile terminal when the inter-network moving is detected by the inter-network moving detection unit and the address allocation module is located at an originally located site of the mobile terminal; and

an allocation unit for allocating a new network layer address to the mobile terminal when the inter-network moving is detected by the inter-network moving detection unit and the address allocation module is located at a visited site of the mobile terminal.

23. The communication system of claim 22, wherein the mobile terminal has:

an inter-network moving judging unit for judging whether or not the inter-network moving is made according to an identifier of the address allocation module or an identifier of a network, which is notified through a radio channel from the router device or the radio base stations; and

a notifying unit for notifying that the inter-network moving is made to at least one of address allocation modules at the originally located site and the visited site of the mobile terminal, when the inter-network moving judging unit judges that the inter-network moving is made, so that the inter-network moving detection unit of the address allocation module detects the inter-network moving according to a notification from the mobile terminal.

24. The communication system of claim 22, wherein the mobile terminal has:

an inter-router moving judging unit for judging whether or not the inter-router moving is made according to an identifier of the router device, which is notified through a radio channel from the router device or the radio base stations; and

a notifying unit for notifying that the inter-router moving is made to at least one of router devices at the originally located site and the visited site of the mobile terminal, when the inter-router moving judging unit judges that the inter-router moving is made, so that the inter-router moving detection unit of the router device detects the inter-router moving according to a notification from the mobile terminal.

25. The communication system of claim 22, wherein the router device also has:

a notifying unit for notifying that the inter-router moving is made to at least one of address allocation modules at the originally located site and the visited site of the mobile terminal when the inter-router moving is detected by the inter-router detection unit, so that the inter-network moving detection unit of the address allocation module detects the inter-network moving according to a notification from the router device.

26. The communication system of claim 22, further comprising:

a charging unit for charging the mobile terminal according to a time for which the network layer address is allocated to the mobile terminal by the address allocation module.

27. The communication system of claim 22, wherein the router device also has:

a connection set up unit for setting up a virtual connection connecting the router device and the mobile terminal or a radio base station accommodating the mobile terminal through another router device at the visited site of the mobile terminal when the inter-router moving is detected by the inter-router moving detection unit;

the updating unit updates the information regarding the routing on the network layer such that datagram destined to the mobile terminal is transferred to the virtual connection set up by the connection set up unit; and

the address allocation module continues to allocate the network layer address allocated to the mobile terminal before the inter-router moving when the connection set up unit of the router device sets up the virtual connection.

28. The communication system of claim 27, wherein the router device also has:

a control unit for controlling an operation mode between a first operation mode to set up the virtual connection and a second operation mode to command the address allocation module to carry out an operation for a case of detecting the inter-network moving, according to an upper layer protocol of the datagram.

29. The communication system of claim 22, wherein the address allocation module allocates a private address as the network layer address, and the communication system further comprises:

at least one gateway device having;

a conversion unit for carrying out conversion between private addresses and global addresses, which is connected with a plurality of networks corresponding to prescribed network layer address allocation ranges; and

an updating unit for updating information required for the conversion when the inter-network moving is made by the mobile terminal.

30. A communication system, comprising:

at least one mobile terminal;

a plurality of radio base stations;

at least one router device having;

a memory unit for storing information regarding a routing on a network layer;

a datagram transfer unit for transferring datagram to a mobile terminal accommodated in a radio base station to which the router device is connected, according to the information regarding the routing on the network layer;

an inter-base station moving detection unit for detecting an inter-base station moving of the mobile terminal among the radio base stations; and

an updating unit for updating the information regarding the routing on the network layer when the inter-base station moving is detected by the inter-base station moving detection unit; and

a terminal location management module having;

an inter-router moving detection unit for detecting an inter-router moving of the mobile terminal between router devices; and

an encapsulated datagram transfer unit for encapsulating datagram destined to the mobile terminal using an address of a network to which a router device or a radio base station of a visited site of the mobile terminal belongs, and transferring encapsulated datagram to the router device of the visited site of the mobile terminal.

31. The communication system of claim 30, wherein the mobile terminal has:

an inter-router moving judging unit for judging whether or not the inter-router moving is made according to an identifier of the router device, which is notified through a radio channel from the router device or the radio base stations; and

a notifying unit for notifying that the inter-router moving is made to the terminal location management module, when the inter-router moving judging unit judges that the inter-router moving is made.

32. The communication system of claim 30, wherein the router device also has:

an inter-router moving detection and notification unit for detecting the inter-router moving by detecting a moving of the mobile terminal between a radio base station connected to the router device and another radio base station connected to another router device, using the inter-base station moving detected by the inter-base station moving detection unit, and notifying that the inter-router moving is made to the terminal location management module.

33. The communication system of claim 30, further comprising:

a delivery module, having an address of a network to which the router device or the radio base station of the visited site of the mobile terminal belongs, for receiving encapsulated datagram, decapsulating the encapsulated datagram, and delivering decapsulated datagram destined to the mobile terminal, when the inter-router moving is made by the mobile terminal.