Wireless communication system and mobile terminal

• US 20050078633A1
• Filed: 08/31/2004
• Published: 04/14/2005
• Est. Priority Date: 10/01/2003
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Koji, Ishifuji, Tomoaki
• Application Number:
  US10/929,625
• Publication Number:
  US 20050078633A1
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 12/5692 Selection among different networks

Abstract

The mobile station has a monitor for monitoring the communication qualities of plural wireless interfaces and selecting one of the wireless interfaces to communicate, and a memory for storing the correspondence between the address unique to the selected wireless interface and the network address unique to the mobile station. The mobile station notifies the gateway of the correspondence. The mobile station supplies power to a not operating wireless interface at constant intervals and during a constant time to monitor the communication quality.

Claims

1. A terminal device connected to a public network through a gateway connected to said public network, and through first and second wireless communication equipments connected to said gateway, said terminal device comprising:

a first wireless interface to communicate with said first wireless communication equipment;

a second wireless interface to communicate with said second wireless communication equipment;

a controller to monitor at least the communication quality of said first wireless interface, and select any one of said wireless interfaces for communication on the basis of said communication quality; and

a memory to store the correspondence of any one of first and second interface addresses assigned to said first and second wireless interfaces as their own addresses with a network address assigned to said terminal device,

wherein said controller causes said interface address of said selected wireless interface for use in wireless communication to be associated with said network address, and said correspondence to be stored in said memory, and

said controller notifies said gateway of said correspondence via said first or second wireless communication equipment.

2. A terminal device according to claim 1, wherein said first wireless interface is a wireless LAN interface, and said second wireless interface is a cellular phone interface for cellular communication.

3. A terminal device according to claim 1, wherein said unique addresses of said wireless interfaces are MAC (Media Access Control) addresses, and said network address is an IP (Internet Protocol) address.

4. A terminal device according to claim 1, wherein said controller, if the communication quality of said first wireless interface does not meet a predetermined criteria during the communication using said first wireless interface, transmits a switching request to said gateway via said first wireless interface, receives a switching response via said first wireless interface, causes said memory to store said correspondence between said second interface address and said network address, and starts the communication using said second wireless interface.

5. A terminal device according to claim 4, wherein said switching request contains said second wireless interface address.

6. A terminal device according to claim 1, wherein said controller, if the communication quality of said first wireless interface meets a predetermined criteria during the communication using said second wireless interface, transmits a switching request to said gateway via said second wireless interface, receives a switching response through said second wireless interface, causes said memory to store said correspondence between said first wireless interface address and said network address, and starts the communication using said first wireless interface.

7. A terminal device according to claim 6, wherein said switching request contains said first wireless interface address.

8. A terminal device according to claim 1, wherein said controller, when said second wireless interface is being operated for communication, controls to supply power to said first wireless interface at intervals of a first period of time and during a second period of time that is shorter than said first period and to measure the quality of communication.

9. A gateway connected to a first wireless communication equipment that communicates with a terminal device having first and second wireless interfaces through said first wireless interface, to a second wireless communication equipment that communicates with said terminal device through said second wireless interface, and to a public network so that said gateway can be used for the communication between said terminal device and said public network, said gateway comprising:

a memory to store an address-correspondence table of the correspondence between a network address and an interface address uniquely assigned to a communication interface of a communication equipment that can communicate via said first wireless communication equipment, said second wireless communication equipment and said public network; and

a transmission controller to determine the interface address of the next destination one of said communication equipments of a received packet by using the header information of said packet and the information of said address-correspondence table, and to transmit said packet to said determined interface address,

wherein said gateway, when receiving a switching request from said terminal device during the communication with said first wireless interface of said terminal device, transmits a switching response back to said first wireless interface, makes the interface address of said second wireless interface correspond to the network address of said terminal device to write said correspondence on said address-correspondence table, and starts the communication between said second wireless interface and said gateway.

10. A gateway according to claim 9, wherein said first or second wireless interface is wireless LAN interface.

11. A gateway according to claim 9, wherein said addresses unique to said communication interfaces are MAC (Media Access Control) addresses, and said network address is an IP (Internet Protocol) address.

12. A gateway according to claim 9, wherein said switching request includes the interface address of said second wireless interface.

13. A gateway according to claim 9, wherein said switching request is transmitted on the basis of the communication quality at said first or second wireless interface.

14. A communication method used in a wireless communication system having a gateway connected to a public network, a first or second wireless communication equipment connected to said gateway, and a terminal device having first and second wireless interfaces provided to communicate with said first and second wireless communication equipments, said method including the steps of:

providing a network address assigned to said terminal device, and first and second interface addresses assigned to said first and second wireless interfaces of said terminal device; and

in said gateway, when the network address of a packet received from said public network is of said terminal device, transmitting said packet to said first or second interface address according to the correspondence, which is previously stored, between said network address and interface addresses of said terminal device,

wherein said correspondence between said network address and interface addresses is stored on the basis of a notice received from said terminal device, indicating which one of said first and second wireless interfaces is used for a communication.

15. A method according to claim 14, wherein said notice is transmitted on the basis of the communication quality of said first or second wireless interface measured in said terminal device.

16. A method according to claim 15, wherein said communication quality is measured at intervals of a predetermined period of time.

17. A method according to claim 14, wherein at least one of said first and second wireless interfaces is a wireless LAN interface.

18. A method according to claim 14, wherein said gateway, when receiving a switching request from said terminal device under a condition that said network address and first wireless interface address of said terminal device are recorded associated with each other, updates the correspondence between said network address and said first wireless interface address to the correspondence between said network address and said second wireless interface address of said terminal device.

19. A method according to claim 18, wherein said gateway transmits a switching response to said first wireless interface in response to said switching request.

20. A method according to claim 18, wherein said switching request indicates the interface address of said second wireless interface.