METHOD AND APPARATUS FOR EFFECTING HANDOFF BETWEEN DIFFERENT CELLULAR COMMUNICATIONS SYSTEMS

• US 20080161001A1
• Filed: 03/17/2008
• Published: 07/03/2008
• Est. Priority Date: 12/07/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rimoni, Yoram, Holcman, Alejandro R.
• Granted Patent: US 7,961,687 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0058 Transmission of hand-off measurement information, e.g. measurement reports
• CPC Class Codes: H04W 36/302 due to low signal strength

Abstract

A method of effecting handoff of a mobile station from a first base station in a first cellular communications system controlled by a first mobile switching control station to a second base station in a second, different cellular system controlled by a second mobile switching control station is described. The method comprises measuring at the mobile station a parameter of a signal transmitted by said first base station and a parameter of a signal transmitted by said second base station. When the parameters reach a predetermined condition, a signal quality message is communicated from the mobile station via the first base station to said first mobile switching control station, which responds by generating information for a channel request message for the second mobile switching control station and transmitting the same to the mobile station. The mobile station generates from the information a channel request message for the second mobile switching control station and transmits the same to the second mobile switching control station. The second mobile switching control station generates channel information identifying a channel in the second communications system for the mobile station so that the handoff may be effected.

Claims

1. A method of effecting handoff of a mobile station from a first base station in a first cellular communications system controlled by a first mobile switching control station to a second base station in a second cellular system controlled by a second mobile switching control station, said first cellular communications system being a CDMA system, and said second cellular system being a GSM system, the method comprising:

measuring at the mobile station a first parameter of a first signal transmitted by said first base station;

measuring at the mobile station a second parameter of a second signal transmitted by said second base station;

communicating a signal quality message from the mobile station via the first base station to said first mobile switching control station, when the first and second parameters reach a predetermined condition;

generating at the first mobile switching control station an Application Data Delivery Service (ADDS) message containing handoff data, the ADDS message being a type of tunneling mechanism, which transparently passes within the CDMA system GSM parameters;

communicating the ADDS message from said first mobile switching control station to said mobile station;

generating at the mobile station a Mobile Application Protocol (MAP) message containing the handoff data; and

communicating the MAP message from the mobile station to the second mobile switching control station.

2. The method as claimed in claim 1, further comprising generating at the second mobile switching control station channel information identifying a channel in the second communications system for the mobile station.

3. The method as claimed in claim 2, further comprising establishing communication between said mobile station and said second base station in the identified channel.

4. The method as claimed in claim 3, further comprising discontinuing communication between said mobile station and said first base station.

5. The method as claimed in claim 1, wherein said first and second parameters correspond to signal strength.

6. The method as claimed in claim 1, wherein said handoff data includes timing information.

7. The method as claimed in claim 6, wherein said handoff data includes authentication data.

8. A mobile station comprising:

a first transceiver chain operable to receive and transmit signals with a first base station in a first cellular communications system, said first cellular communications system being a CDMA system;

a second transceiver chain operable to receive and transmit signals with a second base station in a second cellular communications system, said second cellular communications system being a GSM system; and

a controller for;

measuring a first parameter of a first signal transmitted by said first base station;

measuring a second parameter of a second signal transmitted by said second base station;

communicating a signal quality message from the mobile station via the first base station to said first cellular communications system, when the first and second parameters reach a predetermined condition;

receiving from the first base station an Application Data Delivery Service (ADDS) message containing handoff data, the ADDS message being a type of tunneling mechanism, which transparently passes within the CDMA system GSM parameters;

generating a Mobile Application Protocol (MAP) message containing the handoff data; and

communicating the MAP message to the second base station.

9. The mobile station as claimed in claim 8, wherein the controller is further for receiving from said second base station channel information identifying a channel in the second communications system for the mobile station.

10. The mobile station as claimed in claim 9, wherein the controller is arranged to respond to the channel information by establishing communication between said mobile station and said second base station in the identified channel.

11. The mobile station as claimed in claim 10, herein the controller is arranged to respond to the channel information by discontinuing communication between said mobile station and said first base station.

12. The mobile station as claimed in claim 8, wherein said first and second parameters correspond to signal strength.

13. The mobile station as claimed in claim 8, wherein said handoff data includes timing information.

14. The mobile station as claimed in claim 8, wherein said handoff data includes authentication data.

15. The mobile station as claimed in claim 8, wherein the first transceiver chain is active when the second transceiver chain is inactive.

16. The mobile station as claimed in claim 8, wherein the second transceiver chain is active when the first transceiver chain is inactive.

17. An apparatus for effecting handoff of a mobile station from a first base station in a first cellular communications system controlled by a first mobile switching control station to a second base station in a second cellular system controlled by a second mobile switching control station, said first cellular communications system being a CDMA system, and said second cellular system being a GSM system, the method comprising:

means for measuring at the mobile station a first parameter of a first signal transmitted by said first base station;

means for measuring at the mobile station a second parameter of a second signal transmitted by said second base station;

means for communicating a signal quality message from the mobile station through the first base station to said first mobile switching control station, when the first and second parameters reach a predetermined condition;

means for generating at the first mobile switching control station an Application Data Delivery Service (ADDS) message containing handoff data, the ADDS message being a type of tunneling mechanism, which transparently passes within the CDMA system GSM parameters;

means for communicating the ADDS message from said first mobile switching control station to said mobile station;

means for generating at the mobile station a Mobile Application Protocol (MAP) message containing the handoff data; and

means for communicating the MAP message from the mobile station to the second mobile switching control station.

18. The apparatus as claimed in claim 17, further comprising means for generating at the second mobile switching control station channel information identifying a channel in the second communications system for the mobile station.

19. The apparatus as claimed in claim 18, further comprising means for establishing communication between said mobile station and said second base station in the identified channel.

20. The apparatus as claimed in claim 19, further comprising means for discontinuing communication between said mobile station and said first base station.

21. The apparatus as claimed in claim 17, wherein said first and second parameters correspond to signal strength.

22. The apparatus as claimed in claim 17, wherein said handoff data includes timing information.

23. The apparatus as claimed in claim 17, wherein said handoff data includes authentication data.

24. A computer program product comprising a computer readable medium for effecting handoff of a mobile station from a first base station in a first cellular communications system controlled by a first mobile switching control station to a second base station in a second cellular system controlled by a second mobile switching control station, said first cellular communications system being a CDMA system, and said second cellular system being a GSM system, the computer readable medium further comprising:

code for causing a computer to measure at the mobile station a first parameter of a first signal transmitted by said first base station;

code for causing a computer to measure at the mobile station a second parameter of a second signal transmitted by said second base station;

code for causing a computer to communicate a signal quality message from the mobile station via the first base station to said first mobile switching control station, when the first and second parameters reach a predetermined condition;

code for causing a computer to generate at the first mobile switching control station an Application Data Delivery Service (ADDS) message containing handoff data, the ADDS message being a type of tunneling mechanism, which transparently passes within the CDMA system GSM parameters;

code for causing a computer to communicate the ADDS message from said first mobile switching control station to said mobile station;

code for causing a computer to generate at the mobile station a Mobile Application Protocol (MAP) message containing the handoff data; and

code for causing a computer to communicate the MAP message from the mobile station to the second mobile switching control station.

25. The computer program product as claimed in claim 24, further comprising code for causing a computer to generate at the second mobile switching control station channel information identifying a channel in the second communications system for the mobile station.

26. The computer program product as claimed in claim 25, further comprising code for causing a computer to establish communication between said mobile station and said second base station in the identified channel.

27. The computer program product as claimed in claim 26, further comprising code for causing a computer to discontinue communication between said mobile station and said first base station.

28. The computer program product as claimed in claim 24, wherein said first and second parameters correspond to signal strength.

29. The computer program product as claimed in claim 24, wherein said handoff data includes timing information.

30. The computer program product as claimed in claim 29, wherein said handoff data includes authentication data.