Method and apparatus for adaptive set management in a communication system

• US 7,054,632 B2
• Filed: 11/08/2001
• Issued: 05/30/2006
• Est. Priority Date: 06/26/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Vijayan, Rajiv, Sindhushayana, Nagabhushana T., Attar, Rashid Ahmed
• Primary Examiner(s): Feild, Joseph
• Assistant Examiner(s): Nguyen, Huy D.
• Application Number:
  US10/007,301
• Publication Number:
  US 20020197997A1
• Time in Patent Office: 1,664 Days
• Field of Search: 455/436, 455/437, 455/438, 455/439, 455/442, 455/446, 455/452.2, 455/13.4, 455/15, 455/522, 455/524, 455/574
• US Class Current: 455/436
• CPC Class Codes: H04L 1/20 using signal quality detector
• 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 52/24 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 an adaptive set management in a communication system are disclosed. Certain levels of an imbalance between a forward link and a reverse link are always present in a communication system. Although severe levels of an imbalance cause a detrimental effect on quality of communication and throughput, the imbalance is an issue only if it degrades throughput by one rate on the forward link. Consequently, an adaptive set management evaluates an imbalance among sectors in a subscriber station'"'"'s list in accordance with the quality metric of the forward link and the reverse link, and removes from the subscriber station'"'"'s list only a sector that causes severe imbalance. Although retaining a sector in the subscriber station'"'"'s list may improve throughput, it may negatively affect other functions of the communication system, e.g., power control. Therefore, a method of power control is modified if a level of imbalance affecting the power control is detected.

Claims

1. A method for managing a list of sectors capable of communication with a subscriber station in a communication system, comprising:

receiving a request to remove a sector from the subscriber station'"'"'s list;

determining a reverse link quality metric from the subscriber station at the sector;

retaining the sector in the subscriber station'"'"'s list if said determined reverse link quality metric is sufficient; and

sending the retained sector a data request message on a data request channel;

determining whether an imbalance exists when the sector is retained in the subscriber station'"'"'s list; and

transmitting from at least the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric if the imbalance exists;

wherein said determining whether an imbalance exists comprises;

measuring at each sector belonging to the list reverse link quality metrics of a subscriber station;

determining at each sector belonging to the list a quality metric of a forward link transmitted by the sector to the subscriber station; and

declaring the imbalance if;

the forward link quality metric of one of the plurality of sectors is greater than a forward link quality of the rest of the plurality sectors by a first threshold; and

said measured reverse link quality metric at the one of the plurality sectors is less than said measured reverse link quality at the rest of the plurality sectors by a second threshold.

2. The method as claimed in claim 1, wherein said retaining the sector in the subscriber station'"'"'s list if said determined reverse link quality metric is sufficient comprises:

declining said received request to remove a sector from the subscriber station'"'"'s list.

3. The method as claimed in claim 1, wherein said retaining the sector in the subscriber station'"'"'s list if said determined reverse link quality metric is sufficient comprises:

determining a forward link quality metric at which a rate of data can be decoded; and

setting a forward link quality metric threshold for the sector in accordance with said determined forward link quality metric.

4. The method as claimed in claim 3, wherein said determining a forward link quality metric at which a rate of data can be decoded comprises:

determining a forward link quality metric at which a minimum rate of data can be decoded.

5. The method as claimed in claim 1 further comprising removing the sector from the subscriber station list if said determined reverse link quality metric is insufficient.

6. The method as claimed in claim 1 wherein the communication system comprises the communication system in accordance with IS-856 standard.

7. The method as claimed in claim 1 wherein the communication system comprises the communication system in accordance with IS-95 standard.

8. The method as claimed in claim 1 wherein the communication system comprises the communication system in accordance with Wideband Code-Division-Multiple-Access (WCDMA) standard.

9. The method as claimed in claim 1 wherein the communication system comprises the communication system in accordance with IS-2000 standard.

10. The method as claimed in claim 1 wherein the communication system comprises the communication system in accordance with JSTD-008 standard.

11. The method as claimed in claim 1, further comprising:

determining a forward link quality metric from a sector; and

communicating from the subscriber station a request to remove the sector from the subscriber station list if said determined forward link quality metric is insufficient.

12. An apparatus for managing a list of sectors capable of communication with a subscriber station in a communication system, comprising:

a receiver configured to;

receive a request to remove a sector from the subscriber station'"'"'s list;

a processor communicatively coupled to said receiver; and

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

determine a reverse link quality metric from the subscriber station at the sector; and

retain the sector in the subscriber station list if said determined reverse link quality metric is sufficient;

wherein said set of instructions executable by the processor comprises a set of instructions to;

determine whether an imbalance exists when the sector is retained in the subscriber station'"'"'s list; and

if the imbalance exists then;

provide to at least the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric;

wherein said set of instructions executable by the processor determine whether an imbalance exists comprises a set of instructions to;

determine at each sector belonging to the list reverse link quality metrics of a subscriber station;

determine at each sector belonging to the list a quality metric of a forward link transmitted by the sector to the subscriber station; and

declare the imbalance if;

the forward link quality metric of one of the plurality of sectors is greater than a forward link quality of the rest of the plurality sectors by a first threshold; and

said measured reverse link quality metric at the one of the plurality sectors is less than said measured reverse link quality at the rest of the plurality sectors by a second threshold.

13. The apparatus as claimed in claim 12, wherein said set of instructions executable by the processor to retain the sector in the subscriber station'"'"'s list if said determined reverse link quality metric is sufficient comprises a set of instructions to:

decline said received request to remove a sector from the subscriber station'"'"'s list.

14. The apparatus as claimed in claim 12, wherein said set of instructions executable by the processor to retain the sector in the subscriber station'"'"'s list if said determined reverse link quality metric is sufficient comprises a set of instructions to:

determine a forward link quality metric for the sector at which a rate of data can be decoded; and

set a forward link quality metric threshold in accordance with said determined forward link quality metric.

15. The apparatus as claimed in claim 12, further comprising:

a second receiver configured to measure a forward link quality metric; and

a second transmitter communicatively coupled to said second receiver configured to communicate from the subscriber station to a request to remove the sector from the subscriber station list if said determined forward link quality metric is insufficient.

16. The apparatus as claimed in claim 12, further comprising instructions to remove the sector from the subscriber station list if said determined reverse link quality metric is insufficient.

17. The apparatus as claimed in claim 12 wherein the communication system comprises the communication system in accordance with IS-856 standard.

18. The apparatus as claimed in claim 12 wherein the communication system comprises the communication system in accordance with IS-95 standard.

19. The apparatus as claimed in claim 12 wherein the communication system comprises the communication system in accordance with Wideband Code-Division-Multiple-Access (WCDMA) standard.

20. The apparatus as claimed in claim 12 wherein the communication system comprises the communication system in accordance with IS-2000 standard.

21. The apparatus as claimed in claim 12 wherein the communication system comprises the communication system in accordance with JSTD-008 standard.

22. A method for power controlling a subscriber station, comprising:

measuring at a plurality of sectors belonging to the subscriber station'"'"'s list a reverse link quality metrics of the subscriber station;

determining at each of the sectors a quality metric of a forward link transmitted by the sector to the subscriber station;

determining an imbalance in accordance with said measured reverse link quality metrics, and said determined quality metrics of forward links; and

transmitting from the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric if the imbalance exists;

wherein said determining an imbalance in accordance with said measured reverse link quality metrics, and said determined quality metrics of forward links comprises;

declaring the imbalance if;

the forward link quality metric of one of the plurality of sectors is greater than a forward link quality of the rest of the plurality sectors by a first threshold; and

said measured reverse link quality metric at the one of the plurality sectors is less than said measured reverse link quality at the rest of the plurality sectors by a second threshold.

23. The method as claimed in claim 22 wherein said transmitting from the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric if the imbalance exists comprises:

transmitting from the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric if the imbalance exists for a pre-determined time.

24. The method as claimed in claim 22 wherein said measuring at a plurality of sectors belonging to the subscriber station'"'"'s list a reverse link quality metrics of the subscriber station comprises:

measuring at two of sectors belonging to the subscriber station'"'"'s list a reverse link quality metrics of the subscriber station.

25. An apparatus for power controlling a subscriber station, comprising:

a processor communicatively coupled to said receiver; and

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

determine at each sector belonging to the list reverse link quality metrics of a subscriber station;

determine at each sector belonging to the list a quality metric of a forward link transmitted by the sector to the subscriber station;

determine an imbalance in accordance with said measured reverse link quality metrics, and said determined quality metrics of forward links; and

provide to the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric;

wherein said set of instructions executable by the processor to determine imbalance in accordance with said measured reverse link quality metrics, and said determined quality metrics of forward links comprises a set of instructions to;

declaring the imbalance if;

the forward link quality metric of one of the plurality of sectors is greater than a forward link quality of the rest of the plurality sectors by a first threshold; and

said measured reverse link quality metric at the one of the plurality of sectors is less than said measured reverse link quality at the rest of the plurality sectors by a second threshold.

26. The apparatus as claimed in claim 25 wherein said set of instructions to provide to the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric comprises a set of instruction to:

provide to the sector with the highest forward link quality metric a power control command determined in accordance with the highest reverse link quality metric if the imbalance exists for a pre-determined time.

27. The apparatus as claimed in claim 25 wherein said list includes two sectors.