Method and apparatus for selecting a serving sector in a data communication system

• US 6,757,520 B2
• Filed: 06/26/2001
• Issued: 06/29/2004
• Est. Priority Date: 06/26/2001
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Black, Peter J., Vijayan, Rajiv, Wu, Qiang, Padovani, Roberto, Attar, Rashid A., Sindhushayana, Nagabhushana T., Esteves, Eduardo A. S.
• Primary Examiner(s): Banks-Harold, Marsha D.
• Assistant Examiner(s): Ly, Nghi H
• Application Number:
  US09/892,378
• Publication Number:
  US 20020197959A1
• Time in Patent Office: 1,099 Days
• Field of Search: 455/450, 455/452, 455/62, 455/446, 455/437, 455/63.1, 455/562, 370/331, 370/332, 370/333, 370/335, 370/328
• US Class Current: 455/63.1
• 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 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 remote station and a plurality of sectors in a data communication system, the remote station including a list of eligible sectors, the method comprising:

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

determining a quality metric of a reverse link to each sector in the remote station'"'"'s list, said determining the quality metric of the reverse link to each sector in the remote station'"'"'s list comprising processing at the remote station the forward link from each sector in the remote station'"'"'s list, said processing at the remote station the forward link from each sector in the remote station'"'"'s list comprising;

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

determining the quality metric in accordance with said ascertained first signal value for the at least one sector in the remote station'"'"'s list;

ascertaining a second signal value at a position in a second channel of the forward link for remaining sectors in the remote station'"'"'s list; and

determining a second quality metric in accordance with said ascertained second signal value for the remaining sectors in the remote station'"'"'s list; and

directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list in accordance with said determined quality metric of a forward link and said determined quality metric of a reverse link, said directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list comprising;

assigning credits to each sector in the remote station'"'"'s list except the sector currently serving the remote station in accordance with said determined quality metric of a forward link, said determined quality metric of the reverse link, and said determined second quality metric of the reverse link; and

directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list in accordance with said assigned credits; and

wherein said assigning credits to each sector in the remote station'"'"'s list except the sector currently serving the remote station in accordance with said determined quality metric of a forward link, said determined quality metric of the reverse link, and said determined second quality metric of the reverse link comprises;

decreasing credits of a sector if;

said determined second quality metric of the reverse link for the sector and said determined second quality metric of the reverse link for a sector currently serving the remote station are greater than a second threshold; and

decreasing a first type of credits of a sector if;

said determined quality metric of the reverse link for the sector is insufficient;

or if;

said quality metric of a forward link of the sector is less than the quality metric of the forward link of the sector currently serving the remote station; and

said first quality metric of the reverse link for a sector was not determined.

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 decreasing a first type of credits comprises:

decreasing switching credits of the sector.

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

increasing the first type of credits of a sector if;

the sector'"'"'s quality metric of a forward link is greater than the quality metric of the forward link of the sector currently serving the remote station; and

the sector'"'"'s determined second quality metric of the reverse link is less than the second threshold;

or if;

the sector'"'"'s quality metric of a forward link is greater than the quality metric of the forward link of the sector currently serving the remote station; and

the sector'"'"'s determined quality metric of the reverse link is sufficient; and

increasing a second type of credits of a sector if;

the sector'"'"'s quality metric of a forward link is greater than the quality metric of the forward link of the sector currently serving the remote station;

said determined second quality metric of the reverse link of the sector'"'"'s quality metric of a reverse link is greater than the second threshold; and

said determined second quality metric of the reverse link of the sector currently serving the remote station is less than the second threshold.

5. The method as claimed in claim 1, wherein said increasing a second type of credits comprises:

increasing monitoring credits of the sector.

6. The method as claimed in claim 1, wherein said determining a quality metric to a reverse link for each sector in the remote station'"'"'s list further comprises:

measuring at each sector the quality metric of the reverse link;

processing the quality metric to provide an indicator of the quality metric; and

providing the indicator on a forward link.

7. The method as claimed in claim 6, wherein said providing the indicator on a forward link comprises:

puncturing the indicator into specific positions of the forward link.

8. The method as claimed in claim 6, wherein said providing the indicator into a forward link comprises:

inserting the indicator into a specific position of the forward link.

9. The method as claimed in claim 1, wherein said determining at the remote station a quality metric of a forward link for each sector in the remote station'"'"'s list comprises:

measuring a signal-to-noise-and-interference-ratio of the forward link.

10. The method as claimed in claim 9, 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.

11. The method as claimqd in claim 10, 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.

12. A method for directing communication between a remote station and a plurality of sectors in a data communication system, the remote station including a list of eligible sectors, the method comprising:

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

determining a quality metric of a reverse link to each sector in the remote station'"'"'s list, said determining the quality metric of the reverse link to each sector in the remote station'"'"'s list comprising processing at the remote station the forward link from each sector in the remote station'"'"'s list, said processing at the remote station the forward link from each sector in the remote station'"'"'s list comprising;

combining energy at specific positions of the forward link; and

determining the quality metric in accordance with said combined energy; and

directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list in accordance with said determined quality metric of a forward link and said determined quality metric of a reverse link, said directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list comprising;

assigning credits to each sector in the remote station'"'"'s list except a sector currently serving the remote station in accordance with said determined quality metric of a forward link and said determined quality metric of the reverse link; and

directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list in accordance with said assigned credits;

wherein said assigning credits to each sector in the remote station'"'"'s list except a sector currently serving the remote station in accordance with said determined quality metric of a forward link and said determined quality metric of the reverse link comprises;

increasing temporary credits of a sector if the sector'"'"'s quality metric of a forward link is greater than said quality metric of the forward link of the sector currently serving the remote station modified by a pre-determined value;

decreasing temporary credits of a sector if the sector'"'"'s quality metric of a forward link is less than the quality metric of the forward link of the sector currently serving the remote station modified by a pre-determined value;

assigning credits equal to said temporary credits to a sector if;

said determined quality metric of a reverse link of a sector currently serving the sector is insufficient; and

said determined quality metric of a reverse link of the sector is sufficient; and

assigning credits equal to a value of the sector if;

said determined quality metric of a reverse link of a sector currently serving the sector is sufficient; and

said determined quality metric of a reverse link of the sector is sufficient; and

assigning credits equal to zero to the sector otherwise.

13. The method as claimed in claim 12, wherein said combining energy at specific positions of the forward link comprises:

combining energy at specific, periodic positions of the forward link.

14. The method as claimed in claim 12, wherein said combining energy at specific positions of the forward link comprises:

combining energy at specific positions of the forward link, said specific positions being different for at least two of the sectors.

15. The method as claimed in claim 12, wherein said assigning credits equal to a value of the sector comprises:

assigning credits equal to an update interval of said determining the quality metric in accordance with said combined energy.

16. The method as claimed in claim 12, wherein said directing communication between the remote station and one sector from the sectors in the remote station'"'"'s list in accordance with said assigned credits comprises:

determining sectors with said assigned credits greater than a first threshold; and

directing communication to a sector from said determined sectors with the highest of said assigned credits.

17. The method as claimed in claim 16, further comprising:

directing communication to a sector from said determined sectors with the highest forward link quality metric when at least two of said determined sectors have equal highest assigned credits.