Method and apparatus for performing handoff in communications systems

• US 7,580,709 B2
• Filed: 01/30/2007
• Issued: 08/25/2009
• Est. Priority Date: 11/04/1999
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Black, Peter John
• Primary Examiner(s): Lee; John J
• Application Number:
  US11/668,618
• Publication Number:
  US 20070123261A1
• Time in Patent Office: 938 Days
• Field of Search: 455/436, 455/437, 455/435.2, 455/525, 455/69, 455/439, 455/442, 455/438, 455/522, 455/515, 455/435.1, 455/517, 455/67, 455/13, 455/67.11, 455/412.2, 455/452.1, 455/552.1, 455/452.2, 455/68, 370/318, 370/320, 370/332, 370/333
• US Class Current: 455/437
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/304 due to measured or perceived resources with higher communication quality
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A communication system including a closed loop power control system. Prior to allowing a handoff to a new base station, the subscriber station verifies that its reverse link signal is being received by the destination base station with sufficient energy. The determination is made based on the received reverse link power control commands from the base station. Moreover, a handoff may be forced when the base station providing the best forward link signal is not receiving the reverse link signal from the subscriber station with sufficient energy.

Claims

1. A method for communications by a mobile station, comprising:

determining if a handoff to a base station is necessary;

determining by the mobile station if the base station receives reverse link transmissions with sufficient energy; and

sending a message based on the determination, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.

2. The method of claim 1, wherein the determining if the base station receives reverse link transmissions with sufficient energy is based in part on a message indicating a reverse link quality received from the base station.

3. The method of claim 1, wherein the determining if the base station receives reverse link transmissions with sufficient energy is based in part on reverse link power control commands received from the base station.

4. The method of claim 1, wherein the performing the handoff further comprises prohibiting the handoff to the base station if the base station does not receive reverse link transmissions with sufficient energy.

5. The method of claim 1, wherein the performing the handoff further comprises allowing the handoff to the base station if the base station receives reverse link transmissions with sufficient energy.

6. A mobile station for communications, comprising:

means for determining if a handoff to a base station is necessary;

means for determining by the mobile station if the base station receives reverse link transmissions with sufficient energy; and

means for sending a message based on the determination, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.

7. The mobile station of claim 6, wherein the means determining if the base station receives reverse link transmissions with sufficient energy further comprises means for receiving a message indicating a reverse link quality from the base station.

8. The mobile station of claim 6, wherein the means for determining if the base station receives reverse link transmissions with sufficient energy further comprises means for receiving reverse link power control commands from the base station.

9. The mobile station of claim 6, wherein the means for performing the handoff further comprises means for prohibiting the handoff to the base station if the base station does not receive reverse link transmissions with sufficient energy.

10. The mobile station of claim 6, wherein the means for performing the handoff further comprises means for allowing the handoff to the base station if the base station receives reverse link transmissions with sufficient energy.

11. A computer program product, including a computer readable medium encoded with computer readable instructions for:

determining if a handoff to a base station is necessary;

determining by a mobile station if the base station receives reverse link transmissions with sufficient energy; and

sending a message based on the determination, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.

12. The computer program product of claim 11, wherein the instructions for determining if the base station receives reverse link transmissions with sufficient energy further comprises instructions for receiving a message indicating a reverse link quality from the base station.

13. The computer program product of claim 11, wherein the instructions for determining if the base station receives reverse link transmissions with sufficient energy further comprises instructions for receiving reverse link power control commands from the base station.

14. The computer program product of claim 11, wherein the instructions for performing the handoff further comprises instructions for prohibiting the handoff to the base station if the base station does not receive reverse link transmissions with sufficient energy.

15. The computer program product of claim 11, wherein the instructions for performing the handoff further comprises instructions for allowing the handoff to the base station if the base station receives reverse link transmissions with sufficient energy.

16. A method for communications by a mobile station, comprising:

receiving by the mobile station a message indicating a reverse link quality from a base station;

selecting by the mobile station for the base station with a forward link data transmission if the reverse link quality is above a threshold based on the message; and

sending a message, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.

17. A computer program product including a computer readable medium encoded with computer readable instructions for:

receiving by a mobile station a message indicating a reverse link quality from a base station;

selecting by the mobile station for the base station with a forward link data transmission if the reverse link quality is above a threshold based on the message; and

sending a message, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.

18. A mobile station for communications, comprising:

a receiver configured to receive pilot signals and reverse link power control commands; and

a processor configured to determine if a handoff to a base station is necessary, determine by the mobile station if the base station receives reverse link transmissions with sufficient energy, and to send a message based on the determination, wherein the message indicates the base station for handoff and a requested transmission data rate for the base station.