Methods and apparatus for communicating and/or using transmission power information

• US 20070149238A1
• Filed: 01/17/2006
• Published: 06/28/2007
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rangan, Sundeep, Das, Amab
• Granted Patent: US 8,514,771 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• 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 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/365 Power headroom reporting
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/54 Signalisation aspects of the TPC commands, e.g. frame structure
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless terminal determines the transmission power used for its dedicated control channel at a point in time, and generates a power report indicating a ratio of a maximum wireless terminal transmit power to the transmit power of the dedicated control channel at the point in time. The power report provides a measure of available transmit power for wireless terminal use for other purposes, e.g., uplink traffic channels, after taking into consideration the transmit power used for the dedicated control channel. The point in time has a known time offset from the start of a communications segment in which the power report is transmitted. This allows the base station receiving dedicated control channel uplink signals from the wireless terminal to measure the received signals, receive and process the communicated power report, and correlate information to be used for accurate wireless terminal closed loop power control.

Claims

1. A method of operating a wireless terminal to provide transmission power information to a base station, the method comprising:

generating a power report indicating a ratio of a maximum transmit power of said wireless terminal to the transmit power of a reference signal having a power level known to said wireless terminal at a point in time corresponding to said report;

transmitting the power report; and

repeating said generating and transmitting steps according to a report transmission schedule.

2. The method of claim 1, wherein the power level of said reference signal is controlled by said wireless terminal based on at least one closed loop power level control signal received from a base station.

3. The method of claim 2, wherein said reference signal is a control information signal transmitted over a dedicated control channel to said base station.

4. The method of claim 3 wherein said dedicated control channel is a single tone channel which corresponds to a single logical tone dedicated to said wireless terminal for use in transmitting control information.

5. The method of claim 1, wherein said power report is a power report corresponding to a single instant in time;

and

wherein transmitting the power report includes using a single OFDM tone during each of a plurality of consecutive OFDM symbol transmission time intervals.

6. The method of claim 5, wherein said single OFDM tone is hopped during said plurality of consecutive OFDM symbol transmission time intervals.

7. The method of claim 4, further comprising:

operating the wireless terminal to determine a physical tone to which said logical tone corresponds at different points in time based on tone hopping information.

8. The method of claim 1, wherein the point in time to which a generated power report corresponds has a known offset from a start of a communications segment in which said report is to be transmitted.

9. The method of claim 8, wherein said power report is a backoff report indicates a dB value.

10. The method of claim 9, wherein generating said report included performing a subtraction operation, said subtraction operation including subtracting a per-tone transmission power of an uplink dedicated control channel, in dBm, from a maximum transmission power value of said wireless terminal in dBm.

11. The method of claim 1, wherein the maximum transmission power value depends on a power output capability of said wireless terminal.

12. The method of claim 1, wherein the maximum transmission power value is in compliance with a government regulation limiting the maximum output power level of said wireless terminal.

13. The method of claim 8, wherein transmitting the power report includes transmitting said report as a 5 information bit report coded in a dedicated control channel segment dedicated to said wireless terminal.

14. The method of claim 8, wherein the format of said report depends on which one of a plurality of control information reporting modes of operating said wireless terminal is operating in at the time said report is transmitted.

15. The method of claim 14, wherein when said wireless terminal is operating in a mode in which said wireless is dedicated a single tone channel which is not shared with another wireless terminal, said power report is transmitted as a 5 bit information report.

16. The method of claim 15, wherein when said wireless terminal is operating in a mode in which said wireless terminal is dedicated a portion of a single tone channel, which is used on a time shared basis by at least one other wireless terminal, said power report is transmitted as a 4 bit report which is combined with 4 bits of additional information resulting in a transmitted information unit including 8 bits of information.

17. The method of claim 8, wherein said power report is transmitted twice during each recurring cycle of a dedicated control channel reporting structure used to control transmission of control information by said wireless terminal.

18. The method of claim 17, wherein said power report is transmitted, on average, at least once every 500 OFDM symbol transmission time periods but on average at intervals spaced at least 200 symbol transmission time intervals apart.

19. The method of claim 8, wherein said known reference signal is a signal transmitted on the same channel as said power report.

20. The method of claim 8, wherein said reference signal is a signal which, when received, can be measured at a base station.

21. The method of claim 8, wherein the power report is communicated via a dedicated control channel using a single tone for any OFDM symbol corresponding to the report

22. The method of claim 8, wherein said dedicated control channel signal is a signal which is closed loop power controlled by said base station.

23. The method of claim 1, wherein said maximum transmit power corresponds to a first connection, said method including supporting a second connection in addition to the first connection, said second connection having a second maximum transmit power.

24. The method of claim 23, wherein said second maximum transmit power is different from said maximum transmit power corresponding to the first connection.

25. The method of claim 23, further comprising:

generating a second power report indicating a ratio of the second maximum transmit power of said wireless terminal to a second transmit power of a second reference signal having a second power level known to said wireless terminal at a second point in time corresponding to said second report; and

transmitting the second power report to a base station attachment point corresponding the second connection.

26. The method of claim 23, further comprising:

varying said maximum transmit power corresponding to the first connection over time.

27. The method of claim 26, wherein said varying of the transmit power corresponding to the first connection is performed as a function of the number of concurrent connections maintained by said wireless terminal.

28. A wireless terminal, comprising:

a report generation module for generating a power report indicating a ratio of a maximum transmit power of said wireless terminal to the transmit power of a reference signal having a power level known to said wireless terminal at a point in time corresponding to said report;

a transmitter for transmitting the power report; and

stored transmission schedule information for use in controlling the transmission of reports generated by said report generation module.

29. The wireless terminal of claim 28, a receiver for receiving at least one closed loop power level control signal from a base station;

and

a wireless terminal transmission power control module for controlling wireless terminal transmission power level based on information including said at least one closed loop power level control signal.

30. The wireless terminal of claim 29, wherein said reference signal is a control information signal and wherein said transmitter transmits said reference over a dedicated control channel to said base station.

31. The wireless terminal of claim 30, further comprising:

a dedicated control channel control module for determining which single logical tone in a plurality of logical tones is to be used for said dedicated control channel signaling, said single logical tone being dedicated to said wireless terminal for use in transmitting control information.

32. The wireless terminal of claim 31, wherein said plurality of logical tones are a subset of a larger set of logical uplink tones used by an uplink of said base station.

33. The wireless terminal of claim 28, wherein said power report is a power report corresponding to a single instant in time;

and

wherein transmitting the power report includes using a single OFDM tone. during each of a plurality of consecutive OFDM symbol transmission time intervals.

34. The wireless terminal of claim 33, further comprising:

a tone hopping module for determining at different points in time a single physical OFDM tone to be used to communicate dedicated control channel information during said plurality of consecutive OFDM symbol transmission time intervals.

35. The wireless terminal of claim 31, further comprising:

stored tone hopping information; and

a tone hopping module for determining a physical tone to which said logical tone corresponds at different points in time.

36. The wireless terminal of claim 28, further comprising:

stored time offset information indicating a time offset between the point in time to which a generated power report corresponds and a start of a communications segment in which said report is to be transmitted.

37. The wireless terminal of claim 36, wherein said power report is a backoff report indicates a dB value.

38. The wireless terminal of claim 37, wherein said report generation module includes a computation submodule for subtracting a per-tone transmission power of an uplink dedicated control channel, in dBm, from a maximum transmission power value of said wireless terminal in dBm.

39. The wireless terminal of claim 28, wherein the maximum transmission power value is a set value.

40. The wireless terminal of claim 28, wherein the maximum transmission power value depends on a power output capability of said wireless terminal.

41. The wireless terminal of claim 28, wherein the maximum transmission power value is in compliance with a government regulation limiting the maximum output power level of said wireless terminal.

42. The wireless terminal of claim 36, wherein said transmitter transmits the power report as a five information bit report communicated in a dedicated control channel segment dedicated to said wireless terminal.

43. The wireless terminal of claim 36, further comprising:

a report format control module for controlling the format of said power report as a function of which one of a plurality of dedicated control channel modes of operation are being used at the time the report is transmitted.

44. The wireless terminal of claim 43, wherein when said wireless terminal is operating in a mode in which said wireless is dedicated a single tone channel which is not shared with another wireless terminal, said power report is transmitted as a 5 bit information report.

45. The wireless terminal of claim 44, wherein when said wireless terminal is operating in a mode in which said wireless terminal is dedicated a portion of a single tone channel, which is used on a time shared basis by at least one other wireless terminal, said power report is transmitted as a 4 bit report.

46. The wireless terminal of claim 45, wherein said transmitter transmits said power reports in each of the different modes of operation in transmission segments which are the same size regardless of the mode of operation, the same size segments communicating different numbers of information bits in the different modes of operation, said segment including additional information sent with said power report.

47. The wireless terminal of claim 36, wherein said stored transmission schedule information includes stored recurring reporting schedule information indicating positions within a reporting schedule wherein power reports are to be transmitted.

48. The wireless terminal of claim 47, wherein said reporting schedule information indicates that said power report is to be transmitted at least twice during each recurring cycle of a dedicated control channel reporting structure used to control transmission of control information by said wireless terminal.

49. The wireless terminal of claim 47, wherein said stored reporting schedule information indicates that the power report is to be transmitted, on average, at least once every 500 OFDM symbol transmission time periods but on average at intervals spaced at least 200 symbol transmission time intervals apart.

50. The wireless terminal of claim 36, wherein said known reference signal is a signal transmitted on the same channel as said power report.

51. The wireless terminal of claim 36, wherein said reference signal is a signal which, when received, can be measured at a base station.

52. The wireless terminal of claim 36, wherein the power report is communicated via a dedicated control channel using a single tone for any OFDM symbol corresponding to the report.

53. The wireless terminal of claim 36, further comprising:

a transmitter power control module for performing closed loop power control adjustments of a transmission power level associated with the dedicated control channel.