Systems and methods for performing outer loop power control in wireless communication systems

• US 7,286,846 B2
• Filed: 08/29/2003
• Issued: 10/23/2007
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jou, Yu-Cheun, Chen, Tao, Sarkar, Sandip, Lundby, Stein
• Primary Examiner(s): Corsaro; Nick
• Assistant Examiner(s): Gantt; Alan T.
• Application Number:
  US10/652,355
• Publication Number:
  US 20040162099A1
• Time in Patent Office: 1,516 Days
• Field of Search: 455/522, 455/69, 455/452.1, 455/452.2, 714/18, 370/318, 370/252
• US Class Current: 455/522
• CPC Class Codes: H04W 52/38 TPC being performed in particular situations
• CPC Class Codes: H04W 52/44 in connection with interruption of transmission

Abstract

Systems and methods for controlling the power level for a mobile station during periods when no data is being transmitted by the mobile station. In one embodiment, data is intermittently transmitted from a mobile station to a base station on a reverse-link traffic channel. When data is being transmitted on the traffic channel, the transmitted data is used by the base station to perform power control operations (e.g., incrementing or decrementing the mobile station'"'"'s power level, based upon comparison of a received SNR to a target SNR). When no data is being transmitted on the traffic channel, a “zero-rate indicator” is transmitted on the rate indicator channel. The zero-rate indicator is used by the base station to perform power control. Power control based on the zero-rate indicator may use velocity profiles, reliability metrics or other techniques to control adjustment of the power level.

Claims

1. A system for wireless communication comprising:

a base station; and

a mobile station;

wherein the base station and mobile station are configured to communicate via a plurality of wireless communication channels, including a reverse-link traffic channel and a reverse-link rate indicator channel;

wherein when the mobile station transmits traffic on the reverse-link traffic channel, the mobile station transmits a corresponding rate indicator on the reverse-link rate indicator channel and when the mobile station is not transmitting traffic on the reverse-link traffic channel, the mobile station periodically transmits a zero-rate indicator on the reverse-link rate indicator channel; and

wherein when the base station receives data on the reverse-link traffic channel, the base station performs power control based on the received data and when the base station receives no data on the reverse-link traffic channel, the base station performs power control based on the zero-rate indicator.

2. The system of claim 1, wherein the system conforms to a release of the cdma2000 specification.

3. The system of claim 2, wherein the reverse-link traffic channel comprises a reverse-link enhanced supplemental channel (R-ESCH).

4. The system of claim 2, wherein the reverse-link indicator channel comprises a reverse-link rate indicator channel (R-RICH).

5. The system of claim 1, wherein the zero-rate indicator is transmitted during a portion of each frame period, wherein the portion comprises less than all of the frame period.

6. The system of claim 5, wherein each frame comprises a plurality of sub-frames, wherein the zero-rate indicator is transmitted in one or more of the sub-frames.

7. The system of claim 6, wherein the rate indicator is transmitted in one sub-frame of each frame.

8. The system of claim 7, wherein each frame comprises a 20 ms period that is subdivided into four sub-frames of 5 ms each.

9. A mobile station operable to communicate with a base station via a wireless communication channel, wherein the mobile station comprises:

a processing subsystem; and

a transceiver subsystem coupled to the processing subsystem and configured to transmit data on a reverse link traffic channel and a reverse link rate indicator channel;

wherein the processing subsystem is configured to cause the transceiver subsystem to

transmit a rate indicator signal on the reverse-link rate indicator channel when traffic is being transmitted on the reverse-link traffic channel, wherein the rate indicator signal corresponds to a rate of the traffic being transmitted on the reverse-link traffic channel, and

periodically transmit a zero-rate indicator on the reverse-link rate indicator channel when traffic is not being transmitted on the reverse-link traffic channel.

10. The mobile station of claim 9, wherein the mobile station conforms to a release of the cdma2000 specification.

11. The mobile station of claim 10, wherein the reverse-link traffic channel comprises a reverse-link enhanced supplemental channel (R-ESCH).

12. The mobile station of claim 10, wherein the reverse-link indicator channel comprises a reverse-link rate indicator channel (R-RICH).

13. The mobile station of claim 9, wherein the zero-rate indicator is transmitted during a portion of each frame period, wherein the portion comprises less than all of the frame period.

14. The mobile station of claim 13, wherein each frame comprises a plurality of sub-frames, wherein the zero-rate indicator is transmitted in one or more of the sub-frames.

15. The mobile station of claim 14, wherein the rate indicator is transmitted in one sub-frame of each frame.

16. The mobile station of claim 15, wherein each frame comprises a 20 ms period that is subdivided into four sub-frames of 5 ms each.

17. A base station operable to communicate with a mobile station via a wireless communication channel, wherein the base station comprises:

a processing subsystem; and

a transceiver subsystem coupled to the processing subsystem and configured to receive data on a reverse link traffic channel and a reverse link rate indicator channel;

wherein when the base station receives data on the reverse-link traffic channel, the base station performs power control based on the received data and when the base station receives no data on the reverse-link traffic channel, the base station performs power control based on the zero-rate indicator.

18. The base station of claim 17, wherein the base station conforms to a release of the cdma2000 specification.

19. The base station of claim 18, wherein the reverse-link traffic channel comprises a reverse-link enhanced supplemental channel (R-ESCH).

20. The base station of claim 18, wherein the reverse-link indicator channel comprises a reverse-link rate indicator channel (R-RICH).

21. The base station of claim 17, wherein when the base station receives data on the reverse-link traffic channel, the base station is configured to perform power control by directing a mobile station from which the data is received to increase a power level associated with the mobile station when the received data has a signal to noise ratio (SNR) below a target SNR and to decrease the power level associated with the mobile station when the received data has a SNR above the target SNR.

22. The base station of claim 17, wherein when the base station does not receive data on the reverse-link traffic channel, the base station is configured to perform power control by computing a reliability metric for the zero-rate indicator and incrementing a power level for a mobile station from which the zero-rate indicator is received when the reliability metric indicates that the zero-rate indicator is not reliable, and decrementing the power level when the reliability metric indicates that the zero-rate indicator is reliable.

23. The base station of claim 17, wherein when the base station does not receive data on the reverse-link traffic channel, the base station is configured to perform power control by computing a velocity profile for a mobile station from which the zero-rate indicator is received based upon the power of the zero-rate indicator and adjusting a power level for the mobile station based upon the computed velocity profile.

24. The base station of claim 17, wherein when the base station does not receive data on the reverse-link traffic channel, the base station is configured to perform power control by computing a power density for the zero-rate indicator and adjusting a power level for a mobile station from which the zero-rate indicator is received based upon the computed power density.

25. A method implemented in a system having a reverse-link traffic channel and a reverse-link rate indicator channel, wherein the method comprises:

when traffic is being transmitted on the reverse-link traffic channel,

transmitting a rate indicator signal on the reverse-link rate indicator channel, wherein the rate indicator signal corresponds to a rate of the traffic being transmitted on the reverse-link traffic channel, and

controlling a power level based on the traffic being transmitted on the reverse-link traffic channel; and

when traffic is not being transmitted on the reverse-link traffic channel,

periodically transmitting a zero-rate indicator on the reverse-link rate indicator channel, and

controlling the power level based on the zero-rate indicator.

26. The method of claim 25, wherein the reverse-link traffic channel comprises a cdma2000 reverse-link enhanced supplemental channel (R-ESCH).

27. The method of claim 25, wherein the reverse-link indicator channel comprises a cdma2000 reverse-link rate indicator channel (R-RICH).

28. The method of claim 25, wherein the zero-rate indicator is transmitted during a portion of each frame period, wherein the portion comprises less than all of the frame period.

29. The method of claim 28, wherein each frame comprises a plurality of sub-frames, wherein the zero-rate indicator is transmitted in one or more of the sub-frames.

30. The method of claim 29, wherein the rate indicator is transmitted in one sub-frame of each frame.

31. The method of claim 30, wherein each frame comprises a 20 ms period that is subdivided into four sub-frames of 5 ms each.

32. A method implemented in a mobile station operable to communicate with a base station via a wireless communication link, wherein the method comprises:

if the mobile station has data to transmit, transmitting a rate indicator signal on a reverse-link rate indicator channel, wherein the rate indicator signal corresponds to a rate of traffic being transmitted on a reverse-link traffic channel; and

if the mobile station has no data to transmit, periodically transmitting a zero-rate indicator on the reverse-link rate indicator channel.

33. The method of claim 32, wherein the reverse-link traffic channel comprises a cdma2000 reverse-link enhanced supplemental channel (R-ESCH).

34. The method of claim 32, wherein the reverse-link indicator channel comprises a cdma2000 reverse-link rate indicator channel (R-RICH).

35. The method of claim 32, wherein the zero-rate indicator is transmitted during a portion of each frame period, wherein the portion comprises less than all of the frame period.

36. The method of claim 35, wherein each frame comprises a plurality of sub-frames, wherein the zero-rate indicator is transmitted in one or more of the sub-frames.

37. The method of claim 36, wherein the rate indicator is transmitted in one sub-frame of each frame.

38. The method of claim 37, wherein each frame comprises a 20 ms period that is subdivided into four sub-frames of 5 ms each.

39. A method implemented in a base station operable to communicate with a mobile station via a wireless communication link, wherein the method comprises:

when traffic is being received on a reverse-link traffic channel,

controlling a power level based on the traffic being transmitted on the reverse-link traffic channel; and

when traffic is not being received on the reverse-link traffic channel,

receiving a periodically transmitted zero-rate indicator on a reverse-link rate indicator channel, and

controlling the power level based on the zero-rate indicator.

40. The method of claim 39, wherein the reverse-link traffic channel comprises a cdma2000 reverse-link enhanced supplemental channel (R-ESCH).

41. The method of claim 39, wherein the reverse-link indicator channel comprises a cdma2000 reverse-link rate indicator channel (R-RICH).

42. The method of claim 39, wherein controlling the power level based on the traffic being transmitted on the reverse-link traffic channel comprises directing a mobile station from which the data is received to increase a power level associated with the mobile station when the received data has a signal to noise ratio (SNR) below a target SNR and to decrease the power level associated with the mobile station when the received data has a SNR above the target SNR.

43. The method of claim 39, wherein controlling the power level based on the zero-rate indicator comprises computing a reliability metric for the zero-rate indicator and incrementing a power level for a mobile station from which the zero-rate indicator is received when the reliability metric indicates that the zero-rate indicator is not reliable, and decrementing the power level when the reliability metric indicates that the zero-rate indicator is reliable.

44. The method of claim 39, wherein controlling the power level based on the zero-rate indicator comprises computing a velocity profile for a mobile station from which the zero-rate indicator is received based upon the power of the zero-rate indicator and adjusting a power level for the mobile station based upon the computed velocity profile.

45. The method of claim 39, wherein controlling the power level based on the zero-rate indicator comprises computing a power density for the zero-rate indicator and adjusting a power level for a mobile station from which the zero-rate indicator is received based upon the computed power density.