Method and apparatus for handing over a subscriber unit between celluar communication systems

• US 20060084440A1
• Filed: 10/03/2003
• Published: 04/20/2006
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bakri, Ban Al
• Granted Patent: US 7,400,885 B2
• Time in Patent Office: Days
• US Class Current: 455/439
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 76/27 Transitions between radio resource control [RRC] states

Abstract

The invention relates to handover of a subscriber unit (301,305) from a first cellular communication system (201) to a second cellular communication system (203). The first communication system is for example a UMTS communication system supporting a plurality of connections, and the second communication system is for example a GSM communication system supporting only a single connection. The handover comprises forming a handover connection 219 to the subscriber unit (301,305) through the second communication system and handing one of the connections under the first communication system over to this connection. Rather than dropping the remaining connections, they are entered into a holding state. After the handover, one of the connections on hold may be entered into an active state by associating the handover connection (219) with this connection.

Claims

1. A method of handing over a subscriber unit from a first cellular communication system supporting a plurality of connections of the subscriber unit to a second cellular communication system (having capability for supporting only one connection), the method comprising

entering at least a first connection of said plurality of connections into a holding state;

forming a handover connection to the subscriber unit through the second cellular communication system;

handing over a second connection of said plurality of connections to the second cellular communication system by associating the second connection with said handover connection;

entering said at least first connection into an active state by associating the at least first connection with the handover connection;

2. A method as claimed in claim 1 wherein entering said at least first connection into an active state comprises switching the handover connection from being with the second connection to being with the at least first connection.

3. A method as claimed in claim 1 further comprising selecting the second connection from the plurality of connections in response to at least one characteristic of at least one of the plurality of connections.

4. A method as claimed in claim 3 wherein the characteristic is related to a type of connection.

5. A method as claimed in claim 4 wherein selecting comprises selecting a data service connection in preference to a voice service connection as the second connection.

6. A method as claimed in claim 3 wherein the at least one characteristic comprises at least one characteristic chosen from the group consisting of

a) a priority;

b) a data rate;

c) a propagation characteristic;

d) an error rate;

e) a transaction identifier; and

f) a time of setup of at least one of the plurality of connections.

7. A method as claimed in claim 1 wherein the at least first connection is a data connection and the method comprises

storing data of the at least first connection in memory when the at least first connection is in the holding state;

and

communicating the data stored in said memory when the at least first connection enters the active state.

8. A method as claimed in claim 1 wherein the at least first connection is a data connection and the method comprises

storing data of the at least first connection in memory when the at least first connection is in the holding state;

and

the subscriber unit retrieving the stored data from the memory by setting up a separate data call.

9. A method as claimed in claim 1 further comprising notifying a user of the subscriber unit of which of the plurality of connections are in a holding state.

10. A method as claimed in claim 1 wherein at least one of the plurality of connections is between the subscriber unit and a second cellular communication unit and further comprising notifying a user of the second cellular communication unit of which of the plurality of connections are in a holding state.

11. A method as claimed in claim 9 wherein the notification is by means of a voice communication if at least one of the plurality of connections is a voice service connection.

12. A method as claimed in claim 1 further comprising selecting the second connection in response to a parameter set by an operator of at least one of the first or second cellular communication systems.

13. A method as claimed in claim 1 further comprising selecting the second connection in response to a parameter set by a user of the subscriber unit.

14. A method as claimed in claim 1 wherein if the handover to the second cellular communication system is unsuccessful at least one of the plurality of connections is re-established through the first cellular communication system.

15. A method as claimed in claim 1 wherein the second cellular communication system comprises a master switch center comprising functionality for selecting the second connection out of the plurality of connections.

16. A method as claimed in claim 1 wherein the method is operated in a single integrated master switch centre for the first cellular communication system and the second cellular communication system.

17. A method as claimed in claim 1 wherein the second cellular communication system is operable to only support one connection for each served subscriber unit.

18. A method as claimed in claim 1 wherein the plurality of connections is circuit switched connections.

19. A method as claimed in claim 1 wherein the second cellular communication system is a Second Generation Cellular Communication System.

20. A method as claimed in claim 19 wherein the second cellular communication system is a Global System for Mobile communication (GSM) cellular communication system.

21. A method as claimed in claim 1 wherein the first cellular communication system is a Third Generation Cellular Communication System.

22. A method as claimed in claim 21 wherein the first cellular communication system is a Universal Mobile Telecommunication System (UMTS).

23. A method as claimed in claim 22 wherein entering the at least first connection into a holding state is performed in accordance with at least one of the 3^rd Generation Partnership Project (3G PP) Technical Specifications 22.083, 23.083 and 24.083.

24. A method as claimed in claim 22 wherein entering said at least first connection into an active state is performed in accordance with the 3^rd Generation Partnership Project (3G PP) Technical Specification 24.083.

25. A apparatus for handing over a subscriber unit from a first cellular communication system supporting a plurality of connections of the subscriber unit to a second cellular communication system (having capability for supporting only one connection);

the apparatus comprising;

means for entering at least a first connection of said plurality of connections into a holding state;

means for forming a handover connection to the subscriber unit through the second cellular communication system;

means for handing over a second connection of said plurality of connections to the second cellular communication system by associating the second connection with said handover connection;

means for entering said at least first connection into an active state by associating the at least first connection with the handover connection.