Method and system for selecting a best serving sector in a CDMA data communication system

• US 7,796,563 B2
• Filed: 11/12/2003
• Issued: 09/14/2010
• Est. Priority Date: 10/16/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Attar, Rashid, Black, Peter J., Vijayan, Rajiv, Wu, Qiang, Sindhushayana, Nagabhushana
• Primary Examiner(s): Sheikh; Ayaz R
• Assistant Examiner(s): Wong; Blanche
• Application Number:
  US10/712,630
• Publication Number:
  US 20040095908A1
• Time in Patent Office: 2,498 Days
• Field of Search: None
• US Class Current: 370/335
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point

Abstract

An apparatus for selecting a best serving sector in a code division multiple access (CDMA) communication system. A comparator compares a plurality of signal levels received from a plurality of active sectors with a signal level of a current serving sector to produce a difference. A delta generator is coupled to the comparator that generates a delta credit for each of the plurality of active sectors based on the difference. An accumulator is coupled to the delta generator and accumulates a plurality of delta credits to produce an accumulated total credit. A best sector identifier that is coupled to the accumulator identifies the best serving sector from the accumulated total credit.

Claims

1. An access terminal for selecting a best serving sector in a wireless communication system comprising:

a signal level estimator to deduct an offset value from a fixed rate signal level of a current serving sector and a fixed rate signal level of each of a plurality of active sectors in an active set to generate an adjusted fixed rate signal level for each of the current serving sector and sectors in the active set;

a comparator to determine differences between a plurality of signal levels received from each of the plurality of active sectors and at least the adjusted fixed rate signal level of the current serving sector;

an accumulator for accumulating total credits for each of the plurality of signals from each of the plurality of active sectors based on the comparison; and

a new sector identification module to receive the accumulated total credits and to select the best serving sector among a pool of candidate sectors based on the accumulated total credits.

2. The access terminal of claim 1, wherein the new sector identification module is configured to provide an output of the best sewing sector and transmission mode.

3. The access terminal of claim 2, wherein the transmission mode identifies the best serving sector transmission mode as fixed rate or variable rate.

4. The access terminal of claim 1 further comprising a reverse link power control bit (RPC) filter to evaluate whether a mean RPC exceeds a threshold and determine if a deduction is to be applied to a variable rate signal level.

5. The apparatus of claim 1, further comprising an authorization module coupled to the accumulator and configured to authorize one or more accumulated total credits based in part on an indication of link reliability, and wherein the new sector identification module selects the best serving sector based in part on the authorized accumulated total credits.

6. The apparatus of claim 5, wherein the indication of link reliability comprises a Data Rate Control bit corresponding to an active sector from the plurality of active sectors.

7. The apparatus of claim 5, wherein the authorization module is configured to authorize the one or more accumulated credits by adding a predetermined amount to the one or more accumulated credits.

8. The apparatus of claim 1, wherein the plurality of signal levels received from each of the plurality of active sectors comprises a variable rate signal and fixed rate signal.

9. The apparatus of claim 1, wherein the comparator is further configured to determine differences between each of the plurality of signal levels received from each of the plurality of active sectors and a variable rate signal level of the current serving sector.

10. The apparatus of claim 1, wherein the accumulator is configured to accumulate total credits based on the comparison and a signal level hysteresis.

11. The apparatus of claim 1, wherein the new sector identification module is configured to compare each of the accumulated total credits against a predetermined threshold and select the best serving sector based on the comparison.

12. The apparatus of claim 1, wherein the new sector identification module is configured to determine an adjusted variable rate signal level for each of the plurality of active sectors based on an indication of reliability for each of the plurality of active sectors.

13. The apparatus of claim 1, wherein the new sector identification module is configured to compare an accumulated total credit for a highest variable rate to an accumulated total credit for a highest fixed rate and determine the best serving sector based in part on the comparison.

14. An apparatus for selecting a best serving sector in a code division multiple access (CDMA) communication system, said apparatus comprising;

a comparator comparing each of a plurality of signal levels received from a plurality of active sectors with a signal level of a current serving sector to produce a difference;

an accumulator, coupled to the comparator, for generating a delta credit for each of said plurality of signal levels received from said plurality of active sectors based on said difference and for incrementing a plurality of delta credit counters to produce a delta credit counter for each of said plurality of signals from said plurality of active sectors; and

a best sector identifier, coupled to the accumulator, for identifying said best serving sector from said plurality of delta credit counters.

15. The apparatus of claim 14, wherein said plurality of signal levels received from said plurality of active sectors comprises a fixed rate signal level and a variable rate signal level.

16. The apparatus of claim 15, further comprising an adjustment module for adjusting said fixed rate signal level to produce an adjusted fixed rate signal level.

17. The apparatus of claim 16, further comprising an authorization module for authorizing said plurality of delta credit counters.

18. The apparatus of claim 17, further comprising:

a receiver for receiving a plurality of Data Rate Control (DRC) lock bits; and

an adjustment module for adjusting said variable rate signal level to produce an adjusted variable rate signal level.

19. The apparatus of claim 18, further comprising:

a highest variable rate mode determination module for determining a sector having a highest variable rate mode from said plurality of active sectors; and

a highest fixed rate mode determination module for determining a sector having a highest fixed rate mode from said plurality of active sectors.

20. The apparatus of claim 19, further comprising a preferred mode determination module for determining a preferred mode.