Communication system including method and apparatus for maintaining communications with a mobile terminal

• US 5,533,026 A
• Filed: 03/06/1995
• Issued: 07/02/1996
• Est. Priority Date: 03/06/1995
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation, Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Original Assignee: International Business Machines Corporation
• Inventors: Wetterwald, Michelle M., Solar, Catherine, Bonnet, Roselyne, Lanne, Fabien P., Naghshineh, Mahmoud, Bauchot, Frederic J., Kessler, Ilan, Krishna, Arvind, Ahmadi, Hamid
• Primary Examiner(s): Chin, Wellington
• Application Number:
  US08/398,717
• Time in Patent Office: 484 Days
• Field of Search: 370/95.1, 370/95.3, 370/60, 370/60.1, 370/94.1, 370/94.2, 370/94.3, 455/33.1, 455/33.2, 455/53.1, 455/54.1, 455/54.2, 455/56.1, 379/58, 379/59, 379/60, 379/63
• US Class Current: 370/349
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/26 for hybrid routing by combining proactive and reactive routing
• CPC Class Codes: H04W 40/36 due to handover
• 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]
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

A communications network having a number of routers, a number of base stations and a number of mobile units maintains communications with the mobile units by assigning a unique address known to the routing entities of the network to each mobile unit. By including the mobile units unique address in topology updates of the network, the location of the mobile unit at any time is made known to all routers of the network. That is, once a mobile unit moves into a domain of a new access point and establishes a new link with the new access point, it uses the topology update mechanism of the network to make its new location known to all routers. Once a router of the network receives topology update information specific to the mobile unit'"'"'s new location, it updates its routing table such that packets destined to the mobile unit are routed in a path which terminates at the mobile unit and contains its new access point.

Claims

1. A communication network comprising:

a plurality of stations connected together in a first network for transmitting information between users of the network; and

a plurality of terminals each communication with at least one of said stations through at least one of a plurality of second networks, each of said terminals having a unique network address, wherein said terminals are mobile terminal capable of being moved from said at least one of said plurality of second networks to another one of said plurality of second networks, wherein said terminals store a second network address of said at least one of said plurality of second networks, and wherein each of said terminals includes an address translation means for translating said second network address of said at least one of the plurality of second networks to a second network address of said another one of said plurality of second networks when said terminal is moved from said at least one of said plurality of second networks to said another one of said plurality of second networks.

2. A communications system according to claim 2 wherein each of said second networks is a wireless communications network.

3. A communications system according to claim 3 wherein each of said terminals is a wireless communications terminal capable of being moved from one of said second networks to another of said second networks.

4. A method for communicating between a plurality of terminals in a communications network, comprising the steps of:

assigning a unique address to each terminal communicating over said communications network;

translating a network address to said unique network identification for a destination mobile terminal;

periodically broadcasting routing information from said mobile terminal such that routing information tables in each router in said network are updated such that packets destined to said mobile terminal are forwarded to a next router for delivery of communications packets to said mobile terminal;

transmitting a packet by said mobile terminal after a handoff event to identify a network address of a new network to which said mobile terminal is connected as well as an address of a router of said new network; and

broadcasting a routing information protocol packet after a handoff of a mobile terminal to update routing information tables of each router such that packets destined to said mobile terminal are routed through appropriate routers in said network to said mobile terminal.

5. A method for communicating between a plurality of terminals in a communications network, comprising the steps of:

assigning a unique network address to each mobile terminal in said communications network;

periodically broadcasting routing information such that one or more routing information tables in each of a plurality of routers in said network are updated such that packets destined to said mobile terminal are forwarded to a next router for delivery of communications packets to said mobile terminal;

broadcasting a protocol packet after a handoff of said mobile terminal to update said routing information tables of each said router in said network such that packets destined to said mobile terminal are routed through appropriate routers in said network to said mobile terminal;

changing routing and address information of each said packet destined to said mobile terminal such that said packet appears to have been received from said network with an address uniquely assigned to said mobile terminal; and

changing said routing and address information of each packet such that each said packet received at a base station or a next router appears to have been received from said network to which said base station or said router is connected.

6. A method according to claim 5 wherein said step of periodically broadcasting routing information is executed by said mobile terminal.

7. A method according to claim 5 wherein said step of periodically broadcasting routing information is executed by said base station.

8. A method according to claim 5 wherein said step of broadcasting routing information protocol packets after a handoff is executed by said mobile terminal.

9. A method according to claim 5 wherein said step of broadcasting routing information protocol packets after a handoff is executed by said base station.

10. A method according to claim 5 wherein said step of changing routing and address information of each packet is executed by said mobile terminal.

11. A method according to claim 5 wherein said step of changing routing and address information of each packet is executed by said base station.

12. A method according to claim 5 wherein said step of changing said routing and address information of each packet is executed by said mobile terminal.

13. A method according to claim 5 wherein said step of changing said routing and address information of each packet is executed by said base station.

14. A method according to claim 5 wherein said step of periodically broadcasting routing information and said step of broadcasting protocol packet after a handoff are each executed by said base station.