Method and apparatus for performing idle handoff in a multiple access communication system

• US 6,654,611 B2
• Filed: 05/12/2000
• Issued: 11/25/2003
• Est. Priority Date: 06/07/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tiedemann, Edward G. Jr.
• Primary Examiner(s): VUONG, QUOCHIEN B
• Application Number:
  US09/570,219
• Publication Number:
  US 20020142776A1
• Time in Patent Office: 1,292 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/442, 455/450, 455/453, 455/455, 370/331, 370/332, 370/335, 370/329
• US Class Current: 455/450
• CPC Class Codes: H04W 36/0083 Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 48/10 using broadcasted information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A method and apparatus which permits handoffs while the mobile station is in the system access state. This is achieved by providing for channel assignment messages to be sent over the paging channel of a plurality of base stations, which increases the probability of one of the messages getting through. In addition, this assures the mobile station will be able handoff to a different base station and have a traffic channel allocated to it on the new base station without delay. In addition, a method and apparatus which permits the mobile station to be directly assigned into a soft handoff state upon traffic channel assignment.

Claims

1. A method for receiving channel assignment messages at a mobile station in a code division multiple access (CDMA) system, the method comprising the steps of:

measuring strength of signals from a plurality of base stations;

determining a subset of said plurality of base stations based on the strengths of the signals from said plurality of base stations relative to a predetermined threshold;

transmitting an origination message from said mobile station in an access state, said origination message indicating the base stations in said subset; and

receiving a channel assignment message from each of the base stations of said subset, the channel assignment message indicating a traffic channel.

2. The method of claim 1 wherein said origination message indicates a mobile station identifier.

3. The method of claim 2 wherein the base stations in said subset are identified by a plurality of pilot pseudo-noise (PN) offsets, respectively.

4. The method of claim 1 further comprising the steps of:

demodulating a traffic channel frame from each of said subset of base stations; and

combining said demodulated traffic channel frame to provide an improved estimate of said traffic channel frame.

5. The method as claimed in claim 1 further comprising:

receiving an acknowledgement message from said subset of said plurality of base stations.

6. The method as claimed in claim 1 wherein the step of receiving a channel assignment message comprises:

receiving a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of one of the base stations transmitting said message.

7. The method as claimed in claim 1 wherein the step of receiving a channel assignment message comprises:

receiving a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of each base station of said subset of said plurality of base stations.

8. A code division multiple access (CDMA) mobile station apparatus, comprising:

a receiver configured to;

measure strengths of signals from a plurality of base stations; and

determine a subset of said plurality of base stations based on the strengths of the signals from said plurality of base stations relative to a predetermined threshold; and

a transmitter coupled to said receiver configured to transmit an origination message in an access state, said origination message indicating the base stations in said subset, wherein said receiver is configured to receive a channel assignment message from each of the base stations of said subset, the channel assignment message indicating a traffic channel.

9. The apparatus of claim 8 wherein said origination message indicates a mobile station identifier.

10. The apparatus of claim 9 wherein the base stations in said subset are identified by a plurality of pilot pseudo-noise (PN) offsets, respectively.

11. The apparatus of claim 8 further comprising:

a demodulator configured to demodulate a traffic channel frame from each of said subset of base stations; and

a combiner to combine said demodulated traffic channel frame to provide an improved estimate of said traffic channel frame.

12. The apparatus as claimed in claim 8 wherein said receiver is further configured to

receive an acknowledgement message from said subset of said plurality of base stations.

13. The apparatus as claimed in claim 8 wherein said receiver is further configured to:

receive a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of one of the base stations transmitting said message.

14. The apparatus as claimed in claim 8 wherein said receiver is further configured to:

receive a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of each base station of said subset of said plurality of base stations.

15. A method for receiving channel assignment messages at a mobile station in a code division multiple access (ODMA) system, the method comprising the steps of:

measuring strengths of signals from a plurality of base stations;

determining a subset of said plurality of base stations based on the strengths of the signals from said plurality of base stations relative to a predetermined threshold;

transmitting a page response message from said mobile station in an access state, said page response message indicating the base stations in said subset; and

receiving a paging message from each of the base stations of said subset, the paging message indicating a traffic channel.

16. The method of claim 15 wherein said page response message indicates a mobile station identifier.

17. The method of claim 15 wherein the base stations in said subset are identified by a plurality of pilot pseudo-noise (PN) offsets, respectively.

18. The method of claim 15 further comprising the steps of:

demodulating a traffic channel frame from each of said subset of base stations; and

combining said demodulated traffic channel frame to provide an improved estimate of said traffic channel frame.

19. The method as claimed in claim 15 further comprising:

receiving an acknowledgement message from said subset of said plurality of base stations.

20. The method as claimed in claim 15 wherein the step of receiving a paging message comprises:

receiving a paging message from said subset of said plurality of base stations the paging message indicating traffic channel of one of the base stations transmitting said message.

21. The method as claimed in claim 15 wherein the step of receiving a paging message comprises:

receiving a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of each base station of said subset of said plurality of base stations.

22. A code division multiple access (CDMA) mobile station apparatus, comprising:

a receiver configured to;

measure strengths of signals from a plurality of base stations; and

determining a subset of said plurality of base stations based on the strengths of the signals from said plurality of base stations relative to a predetermined threshold; and

a transmitter coupled to said receiver configured to transmit a page response message in an access state, said page response message indicating the base stations in said subset, wherein said receiver is configured to receive a paging message from each of the base stations of said subset, the paging message indicating a traffic channel.

23. The apparatus of claim 22 wherein said page response message indicates a mobile station identifier.

24. The apparatus of claim 23 wherein the base stations in said subset are identified by a plurality of pilot pseudo-noise (PN) offsets, respectively.

25. The apparatus of claim 22 further comprising:

a demodulator configured to demodulate a traffic channel frame from each of said subset of base stations; and

a combiner to combine said demodulated traffic channel frame to provide an improved estimate of said traffic channel frame.

26. The apparatus as claimed in claim 22 wherein the receiver is further configured to

receive an acknowledgement message from said subset of said plurality of base stations.

27. The apparatus as claimed in claim 22 wherein said receiver is further configured to:

receive a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of one of the base stations transmitting said message.

28. The apparatus as claimed in claim 22 wherein said receiver is further configured to:

receive a paging message from said subset of said plurality of base stations, the paging message indicating traffic channel of each base station of said subset of said plurality of base stations.