Method and system for power control in a communication system

• US 20060093026A1
• Filed: 09/22/2005
• Published: 05/04/2006
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Montojo, Juan, Sankar, Hari, Bao, Gang
• Granted Patent: US 7,657,277 B2
• Time in Patent Office: Days
• US Class Current: 375/225
• CPC Class Codes: H04W 52/267 taking into account the information rate

Abstract

Apparatus and methods efficiently estimate signal-to-noise ratios of a received signal irrespective of intentional adjustments to transmitting power due to fluctuating data rates. For example, in one embodiment, the variation in power due to the change in data rate is decoupled from environmental sources for variations in power. In one embodiment, the signal to noise ratio is adjusted for the data rate. In another embodiment, another signal is used as a reference for the signal to noise computation. This advantageously permits a system to efficiently and accurately control power in a power control loop for efficient use of spectral bandwidth and for relatively good grade of service (GoS).

Claims

1. An apparatus for a wireless communication system, the apparatus comprising:

a receiver configured to receive a transmitted signal from a transmitter having at least a first data rate and a second data rate that is other than the first data rate, wherein a transmitted power of the transmitted signal for the second data rate is adjustable by an offset amount relative to a transmitted power for the first data rate;

a receiver circuit configured to determine a reference signal characteristic associated with the transmitted signal; and

a processing circuit configured to compare the reference signal characteristic to a target and to generate a power control command based at least in part on the comparison and on information provided by the transmitted signal.

2. The apparatus as defined in claim 1, wherein the reference signal characteristic is related to at least a signal-to-noise ratio (SNR).

3. The apparatus as defined in claim 1, wherein the processing circuit is further configured to:

generate a command for an increase in transmitted power when the reference signal characteristic is less than the target; and

generate a command for a decrease in transmitted power when the reference signal characteristic is greater than the target.

4. The apparatus as defined in claim 1, wherein the receiver circuit is further configured to:

determine a signal characteristic of the transmitted signal;

determine a data rate of the transmitted signal;

determine a power offset value used for the transmitted signal at least partially based on the determined data rate; and

combine the power offset value and the signal characteristic to determine the reference signal characteristic.

5. The apparatus as defined in claim 1, wherein the receiver circuit is further configured to:

determine a signal characteristic of the transmitted signal;

determine a power offset used for the transmitted signal at least partially based on a data rate of a second transmitted signal, where the second transmitted signal is sent by a device receiving the transmitted signal; and

combine the power offset and the determined signal characteristic to determine the reference signal characteristic.

6. The apparatus as defined in claim 1, wherein the information comprises a data rate of the transmitted signal.

7. The apparatus as defined in claim 1, wherein the receiver comprises a mobile station and the transmitted signal is transmitted from a base station, wherein the reference signal characteristic is at least partially based on a signal characteristic of a signal transmitted by the base station that is different from the transmitted signal.

8. The apparatus as defined in claim 1, wherein the receiver comprises a mobile station and the transmitted signal is transmitted from a base station, where the receiver circuit is further configured to:

receive a second transmitted signal from the base station;

determine a signal characteristic of the second transmitted signal;

determine an existing transmit power control (TPC) power offset for the transmitted signal; and

use at least the signal characteristic of the second transmitted signal and the TPC power offset to determine the reference signal characteristic.

9. The apparatus as defined in claim 8, wherein the receiver circuit is further configured to determine the existing TPC power offset using a plurality of TPC commands, and to update a count of TPC commands according to the generated power control command.

10. The apparatus as defined in claim 1, where the receiver circuit is further configured to:

receive an indicator of a power offset from the base station; and

generate a power reference value based at least in part on the indicator.

11. A method of controlling power in a wireless communication system, the method comprising:

receiving from a transmitter a transmitted signal having at least a first data rate and a second data rate that is other than the first data rate, wherein a transmitted power of the transmitted signal for the second data rate is adjustable by an offset value relative to a transmitted power for the first data rate;

determining a reference signal characteristic associated with the transmitted signal;

comparing the reference signal characteristic to a target; and

generating a power control command based at least in part on the comparison and on information provided by the transmitted signal.

12. The method as defined in claim 11, wherein the reference signal characteristic comprises at least a reference signal-to-noise ratio (SNR).

13. The method as defined in claim 11, wherein generating the power control command further comprises:

generating a command for an increase in transmitted power when the reference signal characteristic is less than the target; and

generating a command for a decrease in transmitted power when the reference signal characteristic is greater than the target.

14. The method as defined in claim 11, wherein determining the reference signal characteristic further comprises:

determining a signal characteristic of the transmitted signal;

determining a data rate of the transmitted signal;

determining a power offset value used for the transmitted signal at least partially based on the determined data-rate, and

combining the power offset value and the signal characteristic to determine the reference signal characteristic.

15. The method as defined in claim 11, wherein determining the reference signal characteristic further comprises:

determining a signal characteristic of the transmitted signal;

determining a power offset used for the transmitted signal at least partially based on a data rate of a second transmitted signal, where the second transmitted signal is sent to the transmitter; and

combining the power offset and the determined signal characteristic to determine the reference signal characteristic.

16. The method as defined in claim 11, wherein the information comprises at least a data rate of the transmitted signal.

17. The method as defined in claim 11, wherein the method is implemented in a mobile station and the transmitted signal is transmitted from a base station, wherein the reference signal characteristic is based on a signal characteristic of signal a transmitted by the base station that is different from the transmitted signal.

18. The method as defined in claim 11, wherein the method is implemented in a mobile station and the transmitted signal is transmitted from a base station, the method further comprising:

receiving a second transmitted signal from the base station;

determining a signal characteristic of the second transmitted signal;

determining an existing transmit power control (TPC) power offset for the transmitted signal; and

determining the reference signal characteristic based at least in part on the signal characteristic of the second transmitted signal and the TPC power offset.

19. The method as defined in claim 18, wherein determining the existing TPC power offset comprises using a plurality of TPC commands, the method further comprising maintaining a count according to the generated power control command.

20. The method as defined in claim 19, further comprising:

receiving an indicator of a power offset from the base station; and

generating a power reference value based at least in part on the indicator.

21. The method as defined in claim 18, wherein the information comprises information about power offset actually used by the base station.

22. The method as defined in claim 18, wherein the second transmitted signal is transmitted from the base station at a power level independent of data rate.

23. The method as defined in claim 18, further comprising translating the reference signal characteristic to account for at least one of a nominal power offset or a nominal signal-to-noise ratio (SNR) offset between the transmitted signal and the second transmitted signal.

24. The method as defined in claim 11, wherein the transmitted signal carries data modulated with code division multiple access (CDMA), time-division multiple access (TDMA), and is also time-division duplexed (TDD).

25. A method of determining a reference signal characteristic, the method comprising:

determining a signal characteristic of a received signal;

adjusting the signal characteristic with an offset value to account for an adjustment in power due to an adjustment in code rate; and

using the adjusted signal characteristic for power control.

26. A method of determining a signal characteristic, the method comprising:

determining a signal characteristic of a received signal;

separating a first component of the signal characteristic due to channel conditions and a second component due to a power adjustment from a change in data rate; and

using the first component of the signal characteristic for power control.

27. A computer-readable medium having a set of computer-executable instructions, the computer-executable instructions comprising:

a first set of instructions for receiving from a transmitter a transmitted signal having at least a first data rate and a second data rate that is other than the first data rate, wherein a transmitted power of the transmitted signal for the second data rate is adjustable by an offset value relative to a transmitted power for the first data rate;

a second set of instructions for determining a reference signal characteristic associated with the transmitted signal;

a third set of instructions for comparing the reference signal characteristic to a target; and

a fourth set of instructions for generating a power control command based at least in part on the comparison and on information provided by the transmitted signal.

28. A computer-readable medium having a set of computer-executable instructions, the computer-executable instructions comprising:

a first set of instructions for determining a signal characteristic of a received signal;

a second set of instructions for adjusting the signal characteristic with an offset value to account for an adjustment in power due to an adjustment in code rate; and

a third set of instructions for using the adjusted signal characteristic for power control.

29. A computer-readable medium having a set of computer-executable instructions, the computer-executable instructions comprising:

a first set of instructions for determining a signal characteristic of a received signal;

a second set of instructions for separating a first component of the signal characteristic due to channel conditions and a second component due to a power adjustment from a change in data rate; and

a third set of instructions for further comprising using the first component of the signal characteristic for power control.

30. An apparatus for controlling power of a wireless communication system, the apparatus comprising:

means for receiving from a transmitter a transmitted signal having at least a first data rate and a second data rate that is other than the first data rate, wherein a transmitted power of the transmitted signal for the second data rate is adjustable by an offset value relative to a transmitted power for the first data rate;

means for determining a reference signal characteristic associated with the transmitted signal;

means for comparing the reference signal characteristic to a target; and

means for generating a power control command based at least in part on the comparison and on information provided by the transmitted signal.

31. The apparatus as defined in claim 30, wherein the receiving means comprises a base station.

32. The apparatus as defined in claim 30, wherein the receiving means comprises a mobile station.

33. The apparatus as defined in claim 30, wherein the receiving means comprises a receiver, and wherein the compensating means comprises a processor.

34. An apparatus for determining a reference signal characteristic, the apparatus comprising:

means for determining a signal characteristic of a received signal;

means for adjusting the signal characteristic with an offset value to account for an adjustment in power due to an adjustment in code rate; and

means for using the adjusted signal characteristic in a power control loop.

35. The apparatus as defined in claim 34, wherein the determining means comprises a receiver and wherein the adjusting means comprises a processor.

36. An apparatus for determining a signal characteristic, the apparatus comprising:

means for determining a signal characteristic of a received signal;

means for separating a first component of the signal characteristic due to channel conditions and a second component due to a power adjustment from a change in data rate; and

means for using the first component of the signal characteristic for power control.

37. The apparatus as defined in claim 36, wherein the determining means comprises a receiver and the separating means comprises a processor.