METHOD AND APPARATUS FOR OPERATING A DIVERSITY RECEIVER WITH AN EQUALIZER AND A RAKE RECEIVER

• US 20080159373A1
• Filed: 12/12/2007
• Published: 07/03/2008
• Est. Priority Date: 12/14/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Taha, Ali, Hsu, Chih-Ping
• Granted Patent: US 8,594,171 B2
• Time in Patent Office: Days
• US Class Current: 375/232
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Techniques for operating a diversity receiver are described. A user equipment (UE) may include (i) a first receive chain having an equalizer and a first rake receiver and (ii) a second receive chain having a second rake receiver. The UE may support (i) a first mode in which only the equalizer is used to process a received transmission and (ii) a second mode in which both rake receivers are used to process the received transmission. The UE may determine a first performance metric for the first mode (e.g., based on the performance of the equalizer) and a second performance metric for the second mode (e.g., based on the performance of both rake receivers or only the first rake receiver). The UE may select the first or second mode based on the performance metrics and may power down the second receive chain if the first mode is selected.

Claims

1. An apparatus comprising:

at least one processor configured to determine a first performance metric for a first mode with an equalizer in a first receive chain being used to process a received transmission, to determine a second performance metric for a second mode with a first rake receiver in the first receive chain and a second rake receiver in a second receive chain being used to process the received transmission, to select the first or second mode based on the first and second performance metrics, and to power down the second receive chain if the first mode is selected; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the at least one processor is configured to determine the first performance metric based on performance of the equalizer, and to determine the second performance metric based on performance of the first and second rake receivers.

3. The apparatus of claim 2, wherein the at least one processor is configured to determine the first and second performance metrics in each update interval, and to periodically power up the second receive chain in each update interval to determine the second performance metric when the first mode is selected.

4. The apparatus of claim 1, wherein the at least one processor is configured to determine the first performance metric based on performance of the equalizer, and to determine the second performance metric based on performance of only the first rake receiver if the first mode is selected.

5. The apparatus of claim 4, wherein the at least one processor is configured to determine the second performance metric based on performance of both the first and second rake receivers if the second mode is selected.

6. The apparatus of claim 1, wherein the at least one processor is configured to compare the first performance metric against the second performance metric, to select the first mode if the first performance metric is better than the second performance metric, and to select the second mode if the second performance metric is better than the first performance metric.

7. The apparatus of claim 1, wherein the at least one processor is configured to compare the first and second performance metrics against at least one threshold, and to select the first or second mode based on result of the comparison.

8. The apparatus of claim 1, wherein the at least one processor is configured to power up the equalizer and the first rake receiver if the first or second mode is selected, and to power up the second rake receiver only if the second mode is selected.

9. The apparatus of claim 1, wherein the at least one processor is configured to determine a third performance metric for a third mode with the second rake receiver in the second receive chain being used to process the received transmission, and to select the first, second or third mode based on the first, second and third performance metrics.

10. The apparatus of claim 1, wherein the at least one processor is configured to determine a third performance metric for a third mode with the equalizer in the first receive chain and a second equalizer in the second receive chain being used to process the received transmission, and to select the first, second or third mode based on the first, second and third performance metrics.

11. The apparatus of claim 1, wherein the first and second performance metrics comprise at least one of channel quality indicators (CQIs), energy-per-chip-to-total-received-power ratios (Ec/Io), and energy-per-bit-to-total-noise ratios (Eb/Nt).

12. A method comprising:

determining a first performance metric for a first mode with an equalizer in a first receive chain being used to process a received transmission;

determining a second performance metric for a second mode with a first rake receiver in the first receive chain and a second rake receiver in a second receive chain being used to process the received transmission;

selecting the first or second mode based on the first and second performance metrics; and

powering down the second receive chain if the first mode is selected.

13. The method of claim 12, wherein the determining the first performance metric comprises determining the first performance metric based on performance of the equalizer, and wherein the determining the second performance metric comprises determining the second performance metric based on performance of the first and second rake receivers.

14. The method of claim 13, further comprising:

periodically powering up the second receive chain to determine the second performance metric when the first mode is selected.

15. The method of claim 12, wherein the determining the first performance metric comprises determining the first performance metric based on performance of the equalizer, and wherein the determining the second performance metric comprises determining the second performance metric based on performance of only the first rake receiver if the first mode is selected.

16. The method of claim 12, wherein the selecting the first or second mode comprises

comparing the first performance metric against the second performance metric,

selecting the first mode if the first performance metric is better than the second performance metric, and

selecting the second mode if the second performance metric is better than the first performance metric.

17. An apparatus comprising:

means for determining a first performance metric for a first mode with an equalizer in a first receive chain being used to process a received transmission;

means for determining a second performance metric for a second mode with a first rake receiver in the first receive chain and a second rake receiver in a second receive chain being used to process the received transmission;

means for selecting the first or second mode based on the first and second performance metrics; and

means for powering down the second receive chain if the first mode is selected.

18. The apparatus of claim 17, wherein the means for determining the first performance metric comprises means for determining the first performance metric based on performance of the equalizer, and wherein the means for determining the second performance metric comprises means for determining the second performance metric based on performance of the first and second rake receivers.

19. The apparatus of claim 18, further comprising:

means for periodically powering up the second receive chain to determine the second performance metric when the first mode is selected.

20. The apparatus of claim 17, wherein the means for determining the first performance metric comprises means for determining the first performance metric based on performance of the equalizer, and wherein the means for determining the second performance metric comprises means for determining the second performance metric based on performance of only the first rake receiver if the first mode is selected.

21. The apparatus of claim 17, wherein the means for selecting the first or second mode comprises

means for comparing the first performance metric against the second performance metric,

means for selecting the first mode if the first performance metric is better than the second performance metric, and

means for selecting the second mode if the second performance metric is better than the first performance metric.

22. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to determine a first performance metric for a first mode with an equalizer in a first receive chain being used to process a received transmission;

code for causing the at least one computer to determine a second performance metric for a second mode with a first rake receiver in the first receive chain and a second rake receiver in a second receive chain being used to process the received transmission;

code for causing the at least one computer to select the first or second mode based on the first and second performance metrics; and

code for causing the at least one computer to power down the second receive chain if the first mode is selected.

23. The computer program product of claim 22, the computer-readable medium further comprising:

code for causing the at least one computer to determine the first performance metric based on performance of the equalizer; and

code for causing the at least one computer to determine the second performance metric based on performance of the first and second rake receivers.

24. The computer program product of claim 22, the computer-readable medium further comprising:

code for causing the at least one computer to determine the first performance metric based on performance of the equalizer; and

code for causing the at least one computer to determine the second performance metric based on performance of only the first rake receiver if the first mode is selected.