POWER CONTROL IN A WIRELESS COMMUNICATION SYSTEM

• US 20100056197A1
• Filed: 08/26/2009
• Published: 03/04/2010
• Est. Priority Date: 08/27/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Attar, Rashid Ahmed Akbar, Ghosh, Donna, Lott, Christopher Gerard
• Granted Patent: US 8,275,408 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo

Abstract

In a wireless communications system, a serving base station performs outer and closed power control for an overhead channel and a traffic channel for data, either of which can carry an acknowledgement (Ack) channel and Channel Quality Indicator (CQI) channel on an uplink from User Equipment (UE). In an exemplary aspect, data packet communication is implemented in 3GPP LTE Rel. 8 wherein the uplink has a Single Carrier Frequency Division Multiplex (SC-FDM) uplink waveform. The UE performs open loop power control by a determining transmit power spectral density value by using received energy per symbol for a reference signal.

Claims

1. A method for transmitting an uplink in a wireless communication system, comprising:

employing a processor executing computer executable instructions stored on a computer readable storage medium to implement following acts;

receiving a reference signal on a downlink;

determining a transmit power spectral density value by using received energy per symbol for the reference signal;

performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and

transmitting a channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.

2. The method of claim 1, further comprising performing open loop power control based upon a open loop adjust value determined to be equal to an uplink receive power spectral density (RxPSD_ul) value for a user equipment plus a downlink transmit power spectral density (TxPSD_DL) value for a serving node plus a noise figure (NF_NodeB) at the serving node plus a noise over ((NoW)_NodeB) figure at the serving node minus an uplink interference-over-thermal noise (IoT) value at the serving node.

3. The method of claim 1, further comprising:

receiving a command from a node to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to performing outer loop power control, wherein the node determines a detection confidence value for the channel quality feedback and performs outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target; and

transmitting the channel quality feedback on the selected one of the overhead channel or the traffic channel that is subject in part to the transmit power spectral density value determined by open loop power control.

4. A computer program product for transmitting an uplink in a wireless communication system, the computer program product comprising:

at least one computer readable storage medium storing computer executable instructions that, when executed by at least one processor, implement components comprising;

a first set of codes for receiving a reference signal on a downlink;

a second set of codes for determining a transmit power spectral density value by using received energy per symbol for the reference signal;

a third set of codes for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and

a fourth set of codes for transmitting a channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.

5. An apparatus for transmitting an uplink in a wireless communication system, the apparatus comprising:

at least one processor;

at least one computer readable storage medium storing computer executable instructions that, when executed by the at least one processor, implement components comprising;

means for receiving a reference signal on a downlink;

means for determining a transmit power spectral density value by using received energy per symbol for the reference signal;

means for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and

means for transmitting a channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.

6. An apparatus for transmitting an uplink in a wireless communication system, the apparatus comprising:

a receiver for receiving a reference signal on a downlink;

a computing platform for determining a transmit power spectral density value by using received energy per symbol for the reference signal and for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and

a transmitter for transmitting a channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.

7. The apparatus of claim 6, wherein the computing platform is further for performing open loop power control based upon a open loop adjust value determined to be equal to an uplink receive power spectral density (RxPSD_ul) value for a user equipment plus a downlink transmit power spectral density (TxPSD_DL) value for a serving node plus a noise figure (NF_NodeB) at the serving node plus a noise over ((NOW)_NodeB) figure at the serving node minus an uplink interference-over-thermal noise (IoT) value at the serving node.

8. The apparatus of claim 6, wherein the receiver is further for receiving a command from a node to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to an outer loop power control, wherein the node determines a detection confidence value for the channel quality feedback and performs outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target;

and

the transmitter is further for transmitting the channel quality feedback on the selected one of the overhead channel or the traffic channel that is subject in part to the transmit power spectral density value determined by open loop power control.

9. A method for receiving an uplink in a wireless communication system, the method comprising:

employing a processor executing computer executable instructions stored on a computer readable storage medium to implement following acts;

receiving a channel quality feedback on an uplink from a user equipment on a determined one of an overhead channel and a traffic channel;

determining a detection confidence value for the channel quality feedback;

performing outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target; and

transmitting a command to the user equipment to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to performing outer loop power control.

10. The method of claim 9, wherein the detection confidence value comprises an erasure rate.

11. The method of claim 9, further comprising performing outer loop power control for the overhead channel.

12. The method of claim 11, further comprising performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment via a downlink control channel using a grouped power control to adjust the transmit power of the selected one of the overhead channel and traffic channel.

13. The method of claim 11, further comprising:

receiving the channel quality feedback on the overhead channel of the uplink; and

transmitting the command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control.

14. The method of claim 11, further comprising performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control.

15. The method of claim 11, further comprising receiving the channel quality feedback on the traffic channel of the uplink.

16. The method of claim 11, further comprising performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment to adjust the transmit power of the traffic channel of the uplink in accordance to performing outer loop power control.

17. The method of claim 16, further comprising transmitting the command to the user equipment to adjust a gain of a Channel Quality Indicator (CQI) modulation symbol for the channel quality feedback.

18. The method of claim 16, further comprising:

determining a block error rate for the uplink; and

performing outer loop power control to maintain the detection confidence value at the target and to maintain a block error rate for the traffic channel to achieve a desired number of sub-packets.

19. The method of claim 11, further comprising receiving the channel quality feedback on the uplink from a user equipment switching from a selected one to the other of the overhead channel and the traffic channel.

20. The method of claim 19, further comprising transmitting the command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control with a power boost when transitioning from the selected one to the other of the overhead channel and the traffic channel to accommodate a nature of a single carrier frequency division multiplex waveform.

21. The method of claim 20, further comprising determining the power boost to account for a first target value for a difference between a signal-to-noise ratio for a broadcast pilot channel and a second target value for a signal-to-noise ratio for a pilot of the traffic channel.

22. The method of claim 19, further comprising:

receiving the channel quality feedback on the uplink from a user equipment switching from the overhead channel to the traffic channel; and

performing outer loop power control to maintain the detection confidence value at the target based upon a difference in transmit power between a broadcast pilot channel over an entire bandwidth and a pilot for the overhead channel.

23. The method of claim 19, further comprising:

receiving the channel quality feedback on the uplink from a user equipment switching from the traffic channel to the overhead channel; and

performing outer loop power control to maintain the detection confidence value at the target based upon a difference in transmit power between a broadcast pilot channel over a plurality of resources blocks of the overhead channel and a pilot for the traffic channel.

24. The method of claim 11, further comprising transmitting a gain for an uplink acknowledgement set relative to the command to the user equipment to adjust the transmit power of the selected one of the overhead channel and the traffic channel to maintain a target not acknowledged (Nak) to acknowledged (Ack) error rate.

25. The method of claim 9, further comprising performing outer loop power control for the traffic channel.

26. The method of claim 25, further comprising performing outer loop power control for the traffic channel by increasing a pilot signal-to-noise ratio for a pilot the traffic channel to achieve a threshold value for a block error rate for a number of sub-packets.

27. The method of claim 26, further comprising setting increments for increasing the pilot signal-to-noise ratio for smooth dynamics and low setpoint bias.

28. The method of claim 25, further comprising performing outer loop power control for the traffic channel by setting a pilot signal-to-noise ratio setpoint to ensure a target traffic block error rate and a threshold value for a number of sub-packets and to ensure a target erasure rate is achieved when channel quality feedback and data are transmitted on the traffic channel.

29. The method of claim 25, further comprising performing closed loop power control for the traffic channel to maintain a pilot signal-to-noise ratio for the traffic channel at a level defined by performing outer loop power control for the traffic channel based upon an overhead value of a downlink control channel.

30. The method of claim 29, further comprising adjusting a command for a change in power spectral density of transmit power for the traffic channel in response to an interference signal caused by a second user equipment.

31. A computer program product for receiving an uplink in a wireless communication system, the computer program product comprising:

at least one computer readable storage medium storing computer executable instructions that, when executed by at least one processor, implement components comprising;

a first set of codes for receiving a channel quality feedback on an uplink from a user equipment on a determined one of an overhead channel and a traffic channel;

a second set of codes for determining a detection confidence value for the channel quality feedback;

a third set of codes for performing outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target; and

a fourth set of codes for transmitting a command to the user equipment to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to performing outer loop power control.

32. An apparatus for receiving an uplink in a wireless communication system, the apparatus comprising:

at least one processor;

at least one computer readable storage medium storing computer executable instructions that, when executed by the at least one processor, implement components comprising;

means for receiving a channel quality feedback on an uplink from a user equipment on a determined one of an overhead channel and a traffic channel;

means for determining a detection confidence value for the channel quality feedback;

means for performing outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target; and

means for transmitting a command to the user equipment to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to performing outer loop power control.

33. An apparatus for receiving an uplink in a wireless communication system, the apparatus comprising:

a receiver for receiving a channel quality feedback on an uplink from a user equipment on a determined one of an overhead channel and a traffic channel;

a computing platform for determining a detection confidence value for the channel quality feedback and for performing outer loop power control for the determined one of the overhead channel and traffic channel to maintain the detection confidence value at a target; and

a transmitter for transmitting a command to the user equipment to adjust a transmit power of a selected one of the overhead channel and traffic channel that carries the channel quality feedback in accordance to performing outer loop power control.

34. The apparatus of claim 33, wherein the detection confidence value comprises an erasure rate.

35. The apparatus of claim 33, wherein the computing platform is further for performing outer loop power control for the overhead channel.

36. The apparatus of claim 35, wherein the computing platform is further for performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment via a downlink control channel using a grouped power control to adjust the transmit power of the selected one of the overhead channel and traffic channel.

37. The apparatus of claim 35, wherein the receiver is further for receiving the channel quality feedback on an overhead channel of the uplink;

and

the transmitter is further for transmitting the command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control.

38. The apparatus of claim 35, wherein the computing platform is further for performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control.

39. The apparatus of claim 35, wherein the receiver is further for receiving the channel quality feedback on the traffic channel of the uplink.

40. The apparatus of claim 35, wherein the computing platform is further for performing closed loop power control for the overhead channel by transmitting a selected one of an up power control command and a down power control command to the user equipment to adjust the transmit power of the traffic channel of the uplink in accordance to performing outer loop power control.

41. The apparatus of claim 40, wherein the transmitter is further for transmitting the command to the user equipment to adjust a gain of a Channel Quality Indicator (CQI) modulation symbol for the channel quality feedback.

42. The apparatus of claim 40, wherein the computing platform is further for determining a block error rate for the uplink, and for performing outer loop power control to maintain the detection confidence value at the target and to maintain a block error rate for the traffic channel to achieve a desired number of sub-packets.

43. The apparatus of claim 35, wherein the receiver is further for receiving the channel quality feedback on the uplink from a user equipment switching from a selected one to the other of the overhead channel and the traffic channel.

44. The apparatus of claim 43, wherein the transmitter is further for transmitting the command to the user equipment to adjust the transmit power of the overhead channel of the uplink in accordance to performing outer loop power control with a power boost when transitioning from the selected one to the other of the overhead channel and the traffic channel to accommodate a nature of a single carrier frequency division multiplex waveform.

45. The apparatus of claim 44, wherein the computing platform is further for determining the power boost to account for a first target value for a difference between a signal-to-noise ratio for a broadcast pilot channel and a second target value for a signal-to-noise ratio for a pilot of the traffic channel.

46. The apparatus of claim 43, wherein the receiver is further for receiving the channel quality feedback on the uplink from a user equipment switching from the overhead channel to the traffic channel;

and

the computing platform is further for performing outer loop power control to maintain the detection confidence value at the target based upon a difference in transmit power between a broadcast pilot channel over an entire bandwidth and a pilot for the overhead channel.

47. The apparatus of claim 43, wherein the receiver is further for receiving the channel quality feedback on the uplink from a user equipment switching from the traffic channel to the overhead channel;

and

the computing platform is further for performing outer loop power control to maintain the detection confidence value at the target based upon a difference in transmit power between a broadcast pilot channel over a plurality of resources blocks of the overhead channel and a pilot for the traffic channel.

48. The apparatus of claim 35, wherein the transmitter is further for transmitting a gain for an uplink acknowledgement set relative to the command to the user equipment to adjust the transmit power of the selected one of the overhead channel and the traffic channel to maintain a target not acknowledged (Nak) to acknowledged (Ack) error rate.

49. The apparatus of claim 33, wherein the computing platform is further for performing outer loop power control for the traffic channel.

50. The apparatus of claim 49, wherein the computing platform is further for performing outer loop power control for the traffic channel by increasing a pilot signal-to-noise ratio for a pilot the traffic channel to achieve a threshold value for a block error rate for a number of sub-packets.

51. The apparatus of claim 50, wherein the computing platform is further for setting increments for increasing the pilot signal-to-noise ratio for smooth dynamics and low setpoint bias.

52. The apparatus of claim 49, wherein the computing platform is further for performing outer loop power control for the traffic channel by setting a pilot signal-to-noise ratio setpoint to ensure a target traffic block error rate and a threshold value for a number of sub-packets and to ensure a target erasure rate is achieved when channel quality feedback and data are transmitted on the traffic channel.

53. The apparatus of claim 49, wherein the computing platform is further for performing closed loop power control for the traffic channel to maintain a pilot signal-to-noise ratio for the traffic channel at a level defined by performing outer loop power control for the traffic channel based upon an overhead value of a downlink control channel.

54. The apparatus of claim 53, wherein the computing platform is further for adjusting a command for a change in power spectral density of transmit power for the traffic channel in response to an interference signal caused by a second user equipment.