Method and apparatus for choosing a sector based on a scaled forward link metric

• US 8,094,623 B2
• Filed: 03/15/2007
• Issued: 01/10/2012
• Est. Priority Date: 06/26/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Attar, Rashid Ahmed Akbar, Vijayan, Rajiv, Padovani, Roberto, Bhushan, Naga, Wu, Qiang, Black, Peter John, Esteves, Eduardo A. S.
• Primary Examiner(s): Vu, Huy
• Assistant Examiner(s): LAMONT, BENJAMIN S
• Application Number:
  US11/686,772
• Publication Number:
  US 20070153687A1
• Time in Patent Office: 1,762 Days
• Field of Search: 370/331, 370/332, 455/436, 455/437
• US Class Current: 370/332
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]

Abstract

Methods and apparatus for selecting a serving sector in a high rate data (HDR) communication system are disclosed. An exemplary HDR communication system defines a set of data rates, at which a sector of an Access Point may send data packets to an Access Terminal. The sector is selected by the Access Terminal to achieve the highest data throughput while maintaining a targeted packet error rate. The Access Terminal employs various methods to evaluate quality metrics of forward and reverse links from and to different sectors, and uses the quality metrics to select the sector to send data packets to the Access Terminal.

Claims

1. A method for directing communication between a subscriber station and a plurality of sectors in a data communication system, comprising:

determining at the subscriber station a forward link quality metric for each sector in a subscriber station'"'"'s list;

determining a forward link de-rating value for each sector in the subscriber station'"'"'s list, each forward link quality metric being scaled by a corresponding forward link de-rating value to generate a de-rated forward link quality metric for each sector in the subscriber station'"'"'s list;

incrementing credits for each sector in the subscriber station'"'"'s list except a sector currently serving the subscriber station if a first condition is satisfied, wherein the first condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and a de-rated forward link quality metric of the currently serving sector;

decrementing credits for each sector in the subscriber station'"'"'s list except the sector currently serving the subscriber station if a second condition is satisfied, wherein the second condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and the de-rated forward link quality metric of the currently serving sector; and

directing communication between the subscriber station and one sector from the sectors in the subscriber station'"'"'s list, wherein the one sector has accumulated credits greater than a pre-determined threshold.

2. The method as claimed in claim 1, wherein said data communication system comprises a wireless data communication system.

3. The method as claimed in claim 1, wherein said determining at the subscriber station a quality metric of a forward link for each sector in the subscriber station'"'"'s list comprises measuring a signal-to-noise-and-interference-ratio of the forward link.

4. The method as claimed in claim 3, wherein said measuring a signal-to-noise-and-interference-ratio of the forward link comprises measuring a signal-to-noise-and-interference-ratio of a pilot signal on the forward link.

5. The method as claimed in claim 4, wherein said measuring a signal-to-noise-and-interference-ratio of a pilot signal on the forward link comprises measuring a signal-to-noise-and-interference-ratio of a non-continuous pilot signal on the forward link.

6. The method as claimed in claim 1, wherein said determining a forward link de-rating value for each sector in the subscriber station'"'"'s list comprises:

ascertaining at the subscriber station a first signal value at a position in a first channel of the forward link for each sector in the subscriber station'"'"'s list;

processing at the subscriber station said ascertained first signal value for each sector in the subscriber station'"'"'s list; and

determining at the subscriber station the forward link de-rating value in accordance with said processed first signal value for each sector in the subscriber station'"'"'s list.

7. The method as claimed in claim 6, wherein said ascertaining at the subscriber station a first signal value at a position in a first channel of the forward link for each one sector in the subscriber station'"'"'s list comprises ascertaining at the subscriber station a reverse power control bit at a reverse power control channel of the forward link for each sector in the subscriber station'"'"'s list.

8. The method as claimed in claim 6, wherein said determining at the subscriber station the forward link de-rating value in accordance with said processed first signal value for each sector in the subscriber station'"'"'s list comprises:

determining at the subscriber station a first reverse link quality metric in accordance with a pre-determined relationship between said processed first signal value and the first reverse link quality metric; and

determining at the subscriber station the forward link de-rating value in accordance with a pre-determined relationship between the first reverse link quality metric and the forward link de-rating value.

9. An apparatus for directing communication between a subscriber station and a plurality of sectors in a data communication system, comprising:

means for determining at the subscriber station a forward link quality metric for each sector in a subscriber station'"'"'s list;

means for determining a forward link de-rating value for each sector in the subscriber station'"'"'s list, each forward link quality metric being scaled by a corresponding forward link de-rating value to generate a de-rated forward link quality metric for each sector in the subscriber station'"'"'s list;

means for incrementing credits for each sector in the subscriber station'"'"'s list except a sector currently serving the subscriber station if a first condition is satisfied, wherein the first condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and a de-rated forward link quality metric of the currently serving sector;

means for decrementing credits for each sector in the subscriber station'"'"'s list except the sector currently serving the subscriber station if a second condition is satisfied, wherein the second condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and the de-rated forward link quality metric of the currently serving sector; and

means for directing communication between the subscriber station and one sector from the sectors in the subscriber station'"'"'s list, wherein the one sector has accumulated credits greater than a pre-determined threshold.

10. An apparatus for directing communication between a subscriber station and a plurality of sectors in a data communication system, comprising:

a processor; and

a storage medium coupled to the processor and containing a set of instructions executable by the processor to;

determine at the subscriber station a forward link quality metric for each sector in a subscriber station'"'"'s list;

determine a forward link de-rating value for each sector in the subscriber station'"'"'s list, each forward link quality metric being scaled by a corresponding forward link de-rating value to generate a de-rated forward link quality metric for each sector in the subscriber station'"'"'s list;

increment credits for each sector in the subscriber station'"'"'s list except a sector currently serving the subscriber station if a first condition is satisfied, wherein the first condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and a de-rated forward link quality metric of the currently serving sector;

decrement credits for each sector in the subscriber station'"'"'s list except the sector currently serving the subscriber station if a second condition is satisfied, wherein the second condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and the de-rated forward link quality metric of the currently serving sector; and

direct communication between the subscriber station and one sector from the sectors in the subscriber station'"'"'s list, wherein the one sector has accumulated credits greater than a pre-determined threshold.

11. The apparatus as claimed in claim 10, wherein said data communication system comprises a wireless data communication system.

12. The apparatus as claimed in claim 10, wherein said processor is configured to determine at the subscriber station a quality metric of a forward link for each sector in the subscriber station'"'"'s list by executing a set of instructions to measure a signal-to-noise-and-interference-ratio of the forward link.

13. The apparatus as claimed in claim 12, wherein said processor is configured to measure a signal-to-noise-and-interference-ratio of the forward link by executing a set of instructions to measure a signal-to-noise-and-interference-ratio of a pilot signal on the forward link.

14. The apparatus as claimed in claim 10, wherein said processor is configured to determine a forward link de-rating value of each sector in the subscriber station'"'"'s list by executing a set of instructions to:

ascertain at the subscriber station a first signal value at a position in a first channel of the forward link for each sector in the subscriber station'"'"'s list;

process at the subscriber station said ascertained first signal value for each sector in the subscriber station'"'"'s list; and

determine at the subscriber station the forward link de-rating value in accordance with said processed first signal value for each sector in the subscriber station'"'"'s list.

15. The apparatus as claimed in claim 14, wherein said processor is configured to ascertain at the subscriber station a first signal value at a position in a first channel of the forward link for each sector in the subscriber station'"'"'s list by executing a set of instructions to ascertain at the subscriber station a reverse power control bit at a reverse power control channel of the forward link for each sector in the subscriber station'"'"'s list.

16. The apparatus as claimed in claim 14, wherein said processor is configured to process at the subscriber station said ascertained first signal value for each sector in the subscriber station'"'"'s list by executing a set of instructions to filter said ascertained signal value by a filter with a pre-determined time constant.

17. The apparatus as claimed in claim 10, wherein the first condition tests if the de-rated forward link quality metric of the sector is greater than the de-rated forward link quality metric for a sector currently serving the subscriber station modified by the predetermined threshold, and the second condition tests if the de-rated forward link quality metric of the sector is less than the de-rated forward link quality metric for the sector currently serving the subscriber station modified by the predetermined threshold.

18. A tangible, non-transitory storage medium comprising a set of instructions stored thereon executable to:

determine at the subscriber station a forward link quality metric for each sector in a subscriber station'"'"'s list;

determine a forward link de-rating value for each sector in the subscriber station'"'"'s list, each forward link quality metric being scaled by a corresponding forward link de-rating value to generate a de-rated forward link quality metric for each sector in the subscriber station'"'"'s list;

increment credits for each sector in the subscriber station'"'"'s list except a sector currently serving the subscriber station if a first condition is satisfied, wherein the first condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and a de-rated forward link quality metric of the currently serving sector;

decrement credits for each sector in the subscriber station'"'"'s list except the sector currently serving the subscriber station if a second condition is satisfied, wherein the second condition is based on a comparison between a sector'"'"'s de-rated forward link quality metric and the de-rated forward link quality metric of the currently serving sector; and

direct communication between the subscriber station and one sector from the sectors in the subscriber station'"'"'s list, wherein the one sector has accumulated credits greater than a pre-determined threshold.