Distributed reverse channel outer loop power control for a wireless communications system

• US 20040047305A1
• Filed: 08/27/2002
• Published: 03/11/2004
• Est. Priority Date: 08/27/2002
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ulupinar, Fatih
• Application Number:
  US10/228,538
• Publication Number:
  US 20040047305A1
• Time in Patent Office: Days
• US Class Current: 370/320
• CPC Class Codes: H04W 52/125 cascaded outer loop power control
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A distributed power control mechanism having multiple states suitable for use in a wireless communication system. In one aspect, the mechanism includes a distributed adjustment unit comprising data processor, state machine, frame error rate adjuster, and power control threshold adjustment element, where the frame error rate adjuster may be centrally located, such as at a system controller. The data processor receives and processes an input signal to provide status of input signal data frames. The state machine receives frame status and provides a current power control state. The frame error rate adjuster receives frame status and provides an effective current frame error rate. The threshold adjustment element receives frame status, effective current frame error rate, and current power control state and provides a power control setpoint in response thereto.

Claims

1. A system for controlling power level transmission in a wireless communication system, comprising:

a distributed adjustment unit operative to receive and process an input communication signal and provide a power control setpoint, said distributed adjustment unit comprising;

a received data processor operative to receive the input communication signal and provide a frame status for frames of the input communication signal;

a power control state machine operative to receive the frame status from the received data processor and provide a current power control state; and

a power control threshold adjuster receiving the frame status from the received data processor and the current power control state from the power control state machine; and

a central processor comprising;

a frame error rate adjuster, the frame error rate adjuster receiving the frame status and a target frame error rate and periodically computing the effective current frame error rate and distributing the effective current frame error rate to a plurality of distributed adjustment units in the wireless communication system;

wherein the power control threshold adjuster also receives an effective current frame error rate from the central processor and provides the power control setpoint based on the frame status, the current power control state, and the effective current frame error rate.

2. The system of claim 1, wherein the current power control state is defined based on parameters comprising frame status and a prior state.

3. The system of claim 1, wherein frame status indicates receipt of one from a group comprising a good frame, a bad frame, and no received frame for a corresponding frame period.

4. The system of claim 1, wherein the possible power control states comprise a no data state and a normal state.

5. The system of claim 1, wherein the central processor operates to apply a computed correction factor to a dynamically computed error rate.

6. The system of claim 1, wherein the computed correction factor is based on a target frame error rate.

7. The system of claim 6, wherein the computed correction factor is allowed to vary within a set range.

8. The system of claim 1, wherein the power control threshold adjuster computes an effective correction factor based on a correction factor and a degradation factor.

9. The system of claim 8, wherein the degradation factor is computed based on received signal energy.

10. The system of claim 8, wherein the degradation factor is computed based on received power control mean values.

11. The system of claim 1, wherein the distributed adjustment unit is implemented in a BTS and the central processor is implemented in a BSC.

12. The system of claim 1, wherein said system operates over a CDMA communication system.

13. A wireless communication system, comprising:

a central processor comprising an error rate adjuster; and

a remote adjustment unit comprising;

an RF receiver unit operative to receive a modulated signal over a wireless communication link and to condition the received signal to generate a conditioned signal;

a channel processor operative to receive and process the conditioned signal to provide frame status for data received from the modulated signal for a particular data transmission; and

a distributed power control processor operative to receive the frame status and provide an effective current frame error rate in response thereto;

wherein the error rate adjuster receives the frame status and computes the effective current frame error rate and transmits the effective current frame error rate to the distributed power control processor of the distributed adjustment unit;

and further wherein the distributed power control processor comprises a distributed threshold adjustment element operative to receive the frame status, a target frame error rate, and the effective current frame error rate and provide the effective current frame error rate in response thereto.

14. The wireless communication system of claim 13, wherein the channel processor comprises:

signal quality measurement circuitry operative to receive the conditioned signal and provide an indication of a signal quality for the conditioned signal, and

a data processor operative to receive, demodulate, and decode the conditioned signal to provide the frame status.

15. A power control unit for use in a wireless communication system, comprising:

a distributed data processor operative to receive and process an input signal to provide status of frames of data received from the input signal for a particular data transmission;

a distributed state machine operative to receive the frame status and provide a current power control state for the power control unit, wherein the current power control state is indicative of a status of a particular communication session comprising the data transmission, and wherein the current power control state is one of a plurality of possible states for the power control unit;

a central error rate adjustment element operative to receive frame status and provide an effective current error rate in response thereto; and

a distributed power control threshold adjustment element operative to receive frame status, error rate, and the current power control state and to provide a power control setpoint in response thereto.

16. The power control unit of claim 15, wherein the communication session is characterized by non-continuous data transmission comprising bursts of data transmission separated by periods of no transmission.

17. The power control unit of claim 15, wherein the current state is defined based on parameters comprising frame status and a prior state.

18. The power control unit of claim 15, wherein frame status indicates receipt of one from a group comprising a good frame, a bad frame, and no received frame for a corresponding frame period.

19. The power control unit of claim 15, wherein the possible states comprise a no data state and a normal state.

20. The power control unit of claim 15, wherein the remote error rate adjustment element operates to apply a computed correction factor to a dynamically computed error rate.

21. The power control unit of claim 20, wherein the computed correction factor is based on a target frame error rate.

22. The power control unit of claim 20, wherein the computed correction factor is allowed to vary within a set range.

23. The power control unit of claim 22, wherein the set range depends upon the target error rate.

24. The power control unit of claim 21, wherein the distributed power control threshold adjustment element computes an effective correction factor, wherein the effective correction factor is based on a correction factor and a degradation factor.

25. The power control unit of claim 24, wherein the degradation factor is computed based on received signal energy.

26. The power control unit of claim 24, wherein the degradation factor is computed based on received power control mean values.

27. The power control unit of claim 15, wherein the power control unit is operated to adjust a transmit power level of a reverse link transmission from a terminal to a BTS.

28. The power control unit of claim 15, wherein one or more frames are received for a particular transmitted data frame and wherein the frame status corresponding to the transmitted frame is considered a good frame if at least one of the one or more received frames is determined to be a good frame.

29. The power control unit of claim 15, wherein one or more frames are received for a particular transmitted data frame and wherein the frame status corresponding to the transmitted frame is considered a bad frame if all of the one or more received frames are determined to be bad frames.

30. The power control unit of claim 15, wherein the central error rate adjustment element computes an effective current error rate adjustment and transmits the effective current error rate adjustment to at least one BTS.

31. The power control unit of claim 15, wherein the central error rate adjustment element operates at a BSC and the distributed power control threshold adjustment element operates at a BTS.

32. The power control unit of claim 15, operated on a reverse link data transmission in a CDMA communication system.

33. A method of providing power control of a transmitted signal in a wireless communication spectrum, comprising:

receiving and processing the transmitted signal to provide frame status for frames of data received from the received and processed signal for a particular data transmission at a distributed adjustment unit;

centrally computing an effective current frame error rate based on the frame status and a predetermined set of criteria and providing the effective current frame error rate to the distributed adjustment unit; and

adjusting a power control setpoint in response to frame status and the error rate adjustment factor.

34. The method of claim 33, further comprising determining a current power control state, and wherein said power control setpoint adjusting is further in response to the current power control state.

35. The method of claim 33, wherein centrally computing the effective current frame error rate comprises:

dynamically computing a current frame error rate; and

applying a correction factor to the current frame error rate based on received frame quality and target frame error rate.

36. The method of claim 33, wherein current frame error rate is maintained within a computed bounded limit.

37. The method of claim 33, wherein centrally adjusting the power control setpoint comprises computing an effective bad frame adjustment quantity based on a bad frame adjustment quantity and a degradation factor.

38. The method of claim 37, wherein the degradation factor is based on received signal energy.

39. The method of claim 37, wherein the degradation factor is based on received power control mean values.

40. A computer program embodied on a computer readable medium for providing power control of a transmitted signal in a wireless communication system, comprising:

a distributed data processing code segment comprising an input signal processor having the ability to receive an input signal and provide frame status data for the input signal;

a central error rate adjustment code segment comprising a correction adjustment computational segment and boundary evaluation segment, wherein a target error rate is corrected using the correction adjustment computational segment as bounded by the boundary evaluation segment; and

a distributed power control threshold adjustment segment comprising a correction application segment that corrects a power control threshold setpoint based on the frame status and the error rate adjustment.

41. The computer program of claim 40, further comprising a central power control state computation segment for computing a state based on frame status and providing the state to the power control threshold adjustment segment.

42. A system for providing power control for a transmitted signal in a wireless communication spectrum, comprising:

a distributed adjustment unit receiving means for receiving and processing the transmitted signal to provide frame status for frames of data received from the received and processed signal for a particular data transmission;

central frame error rate adjustment means for determining an effective current frame error rate based on the frame status and a predetermined set of criteria; and

distributed adjustment means for adjusting a power control setpoint in response to frame status and the effective current error rate.

43. The system of claim 42, further comprising distributed power control state determining means for determining a current power control state, wherein said distributed adjustment computing means further operate in response to the current power control state.

44. The system of claim 42, wherein the central frame error adjustment means comprises:

means for dynamically computing a current error rate; and

means for applying a correction factor to the current error rate based on received frame quality and target frame error rate.

45. The system of claim 44, wherein current error rate is maintained within a computed bounded limit.

46. The system of claim 42, wherein the distributed adjustment computing means comprises means for computing an effective bad frame adjustment quantity based on a bad frame adjustment quantity and a degradation factor.

47. A distributed adjustment unit operative to receive and process an input communication signal and provide a power control setpoint, said distributed adjustment unit comprising:

a received data processor operative to receive the input communication signal and provide a frame status for frames of the input communication signal;

a power control state machine operative to receive the frame status from the received data processor and provide a current power control state; and

a power control threshold adjuster receiving the frame status from the received data processor, the current power control state from the power control state machine, and an effective current frame error rate from a central processor and provide the setpoint in response thereto.

48. The distributed adjustment unit of claim 47, wherein the central processor receives the frame status and a target frame error rate and periodically computes the effective current frame error rate and distributes the effective current frame error rate to at least one distributed adjustment unit.

49. The distributed adjustment unit of claim 47, wherein the current power control state is defined based on parameters comprising frame status and a prior state.

50. The distributed adjustment unit of claim 47, wherein frame status indicates receipt of one from a group comprising a good frame, a bad frame, and no received frame for a corresponding frame period.

51. The distributed adjustment unit of claim 47, wherein the possible power control states comprise a no data state and a normal state.

52. The distributed adjustment unit of claim 47, wherein the power control threshold adjuster computes an effective correction factor, and wherein the effective correction factor is based on a correction factor and a degradation factor.

53. The distributed adjustment unit of claim 52, wherein the degradation factor is computed based on received signal energy.

54. The distributed adjustment unit of claim 52, wherein the degradation factor is computed based on received power control mean values.

55. The distributed adjustment unit of claim 52, wherein the distributed adjustment unit provides the setpoint from a BTS to a terminal.

56. A method for providing a transition by a terminal between a first transmitter and a second transmitter, comprising:

receiving frames transmitted by the terminal at the first transmitter and second transmitter;

determining a first frame status at the first transmitter;

determining a second frame status at the second transmitter;

transmitting a first degraded power control command from the first transmitter to the terminal, wherein the first degraded power control command approaches a first ideal power control command when the first transmitter is determined to be the power controlling transmitter and the first degraded power control command approaches zero otherwise, wherein degradation of the first degraded power control command is based in part on the first frame status; and

transmitting a second degraded power control command from the second transmitter to the terminal, wherein the second degraded power control command approaches a second ideal power control command when the second transmitter is determined to be the power controlling transmitter and the second degraded power control command approaches zero otherwise, wherein degradation of the second power control command is based in part on the second frame status.

57. The method of claim 56, wherein degradation of the first power control command and the second power control command are based on received power signal at each transmitter and a current power control command.

58. The method of claim 56, wherein degradation of the first power control command and the second power control command are based on mean reverse power control transmissions by each transmitter.

59. The method of claim 58, wherein mean reverse power control transmissions corresponding to a plurality of commands to increase terminal power indicate the first power control command and second power control command approach zero.

60. The method of claim 56, wherein degradation of the first power control command and second power control command is based on received signal energy.

61. The method of claim 56, wherein degradation of the first power control command and second power control command is based on received power control mean values.