METHODS AND APPARATUS FOR SCALING TRANSMIT POWER OF SIGNALS IN WIRELESS COMMUNICATIONS

• US 20110086679A1
• Filed: 10/08/2009
• Published: 04/14/2011
• Est. Priority Date: 10/08/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jovicic, Alexsandar, Tavildar, Saurabh, Richardson, Thomas, Li, Junyi
• Granted Patent: US 8,934,353 B2
• Time in Patent Office: Days
• US Class Current: 455/572
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/38 TPC being performed in particular situations
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment

Abstract

Methods and apparatus of varying transmit power of signals for increasing system throughput and spectral reuse in an unlicensed spectrum are disclosed. One method includes transmitting from a first mobile device to a second mobile device a request to send (RTS) signal having a first transmit data power level based on a channel gain between the first mobile device and the second mobile device, receiving, at the first mobile device, a clear to send (CTS) signal from the second mobile device, and transmitting data at the first transmit data power level from the first mobile device to the second mobile device.

Claims

1. A method of increasing system throughput in an unlicensed spectrum comprising:

transmitting from a first mobile device to a second mobile device a first request to send (RTS) signal having a first transmit data power level based on a channel gain between the first mobile device and the second mobile device;

receiving, at the first mobile device, a first clear to send (CTS) signal from the second mobile device; and

transmitting data at the first transmit data power level from the first mobile device to the second mobile device.

2. The method of claim 1 wherein the first transmit data power level is inversely proportional to or monotonically decreasing with the channel gain between the first mobile device and the second mobile device.

3. The method of claim 1 wherein the channel gain is determined from a prior signal transmitted from the second mobile device to the first mobile device.

4. The method of claim 1 wherein:

the second mobile device receives the first RTS signal having a first received RTS power level; and

the second mobile device transmits the first CTS signal having a first transmit CTS power level that is a function of the first received RTS power level.

5. The method of claim 4 wherein the function is selected from a group consisting of inversely proportional to the first received RTS power level and monotonically decreasing with the first received RTS power level.

6. The method of claim 1 further comprising:

receiving, at a third mobile device, the first RTS signal from the first mobile device having a second received RTS power level;

receiving, at the third mobile device, a second RTS signal from a fourth mobile device having a third received RTS power level; and

determining, at the third mobile device, whether to transmit a second CTS signal to the fourth mobile device based on a predetermined function of the second received RTS power level and the third received RTS power level.

7. The method of claim 6 wherein the predetermined function compares the ratio of the second received RTS power level and the third received RTS power level to a predetermined threshold.

8. The method of claim 6 further comprising:

receiving, at the fourth mobile device, the first CTS signal from the second mobile device, the first CTS signal having a second received CTS power level;

receiving, at the fourth mobile device, the second CTS signal from the third mobile device; and

determining, at the fourth mobile device, whether to transmit a data signal based on a predetermined function of the second received CTS power level.

9. The method of claim 8 wherein the predetermined function compares the product of the second received CTS power level and a second transmit data power level to a predetermined threshold.

10. The method of claim 9 wherein the second transmit data power level is to be used by the fourth mobile device to transmit a second RTS signal to the third mobile device or a data signal to the third mobile device.

11. The method of claim 10 wherein the second transmit data power level is inversely proportional to or monotonically decreasing with a channel gain between the third mobile device and the fourth mobile device.

12. The method of claim 11 wherein the channel gain is determined from a prior signal transmitted from the third mobile device to the fourth mobile device.

13. An apparatus for increasing system throughput in an unlicensed spectrum comprising:

a processor configured to;

transmit from a first mobile device to a second mobile device a first request to send (RTS) signal having a first transmit data power level based on a channel gain between the first mobile device and the second mobile device;

receive, at the first mobile device, a first clear to send (CTS) signal from the second mobile device; and

transmit data at the first transmit data power level from the first mobile device to the second mobile device.

14. The apparatus of claim 13 wherein the first transmit data power level is inversely proportional to or monotonically decreasing with the channel gain between the first mobile device and the second mobile device.

15. The apparatus of claim 13 wherein the channel gain is determined from a prior signal transmitted from the second mobile device to the first mobile device.

16. The apparatus of claim 13 wherein:

the second mobile device receives the first RTS signal having a first received RTS power level; and

the second mobile device transmits the first CTS signal having a first transmit CTS power level that is a function of the first received RTS power level.

17. The apparatus of claim 16 wherein the function is selected from a group consisting of inversely proportional to the first received RTS power level and monotonically decreasing with the first received RTS power level.

18. The apparatus of claim 13 wherein the processor is further configured to:

receive, at a third mobile device, the first RTS signal from the first mobile device having a second received RTS power level;

receive, at the third mobile device, a second RTS signal from a fourth mobile device having a third received RTS power level; and

determine, at the third mobile device, whether to transmit a second CTS signal to the fourth mobile device based on a predetermined function of the second received RTS power level and the third received RTS power level.

19. The apparatus of claim 18 wherein the predetermined function compares the ratio of the second received RTS power level and the third received RTS power level to a predetermined threshold.

20. The apparatus of claim 18 wherein the processor is further configured to:

receive, at the fourth mobile device, the first CTS signal from the second mobile device, the first CTS signal having a second received CTS power level;

receive, at the fourth mobile device, the second CTS signal from the third mobile device; and

determine, at the fourth mobile device, whether to transmit a data signal based on a predetermined function of the second received CTS power level.

21. The apparatus of claim 20 wherein the predetermined function compares the product of the second received CTS power level and a second transmit data power level to a predetermined threshold.

22. The apparatus of claim 21 wherein the second transmit data power level is to be used by the fourth mobile device to transmit a second RTS signal to the third mobile device or a data signal to the third mobile device.

23. The apparatus of claim 22 wherein the second transmit data power level is inversely proportional to or monotonically decreasing with a channel gain between the third mobile device and the fourth mobile device.

24. The apparatus of claim 23 wherein the channel gain is determined from a prior signal transmitted from the third mobile device to the fourth mobile device.

25. An apparatus for increasing system throughput in an unlicensed spectrum comprising:

means for transmitting from a first mobile device to a second mobile device a first request to send (RTS) signal having a first transmit data power level based on a channel gain between the first mobile device and the second mobile device;

means for receiving, at the first mobile device, a first clear to send (CTS) signal from the second mobile device; and

means for transmitting data at the first transmit data power level from the first mobile device to the second mobile device.

26. The apparatus of claim 25 wherein the first transmit data power level is inversely proportional to or monotonically decreasing with the channel gain between the first mobile device and the second mobile device.

27. The apparatus of claim 25 wherein the channel gain is determined from a prior signal transmitted from the second mobile device to the first mobile device.

28. The apparatus of claim 25 wherein:

the second mobile device receives the first RTS signal having a first received RTS power level; and

the second mobile device transmits the first CTS signal having a first transmit CTS power level that is a function of the first received RTS power level.

29. The apparatus of claim 28 wherein the function is selected from a group consisting of inversely proportional to the first received RTS power level and monotonically decreasing with the first received RTS power level.

30. The apparatus of claim 25 further comprising:

means for receiving, at a third mobile device, the first RTS signal from the first mobile device having a second received RTS power level;

means for receiving, at the third mobile device, a second RTS signal from a fourth mobile device having a third received RTS power level; and

means for determining, at the third mobile device, whether to transmit a second CTS signal to the fourth mobile device based on a predetermined function of the second received RTS power level and the third received RTS power level.

31. The apparatus of claim 30 wherein the predetermined function compares the ratio of the second received RTS power level and the third received RTS power level to a predetermined threshold.

32. The apparatus of claim 30 further comprising:

means for receiving, at the fourth mobile device, the first CTS signal from the second mobile device, the first CTS signal having a second received CTS power level;

means for receiving, at the fourth mobile device, the second CTS signal from the third mobile device; and

means for determining, at the fourth mobile device, whether to transmit a data signal based on a predetermined function of the second received CTS power level.

33. The apparatus of claim 32 wherein the predetermined function compares the product of the second received CTS power level and a second transmit data power level to a predetermined threshold.

34. The apparatus of claim 33 wherein the second transmit data power level is to be used by the fourth mobile device to transmit a second RTS signal to the third mobile device or a data signal to the third mobile device.

35. The apparatus of claim 34 wherein the second transmit data power level is inversely proportional to or monotonically decreasing with a channel gain between the third mobile device and the fourth mobile device.

36. The apparatus of claim 35 wherein the channel gain is determined from a prior signal transmitted from the third mobile device to the fourth mobile device.

37. A machine readable medium embodying machine executable instructions to implement a method of increasing system throughput in an unlicensed spectrum, the method comprising:

transmitting from a first mobile device to a second mobile device a first request to send (RTS) signal having a first transmit data power level based on a channel gain between the first mobile device and the second mobile device;

receiving, at the first mobile device, a first clear to send (CTS) signal from the second mobile device; and

transmitting data at the first transmit data power level from the first mobile device to the second mobile device.

38. The machine readable medium of claim 37 wherein the first transmit data power level is inversely proportional to or monotonically decreasing with the channel gain between the first mobile device and the second mobile device.

39. The machine readable medium of claim 37 wherein the channel gain is determined from a prior signal transmitted from the second mobile device to the first mobile device.

40. The machine readable medium of claim 37 wherein:

the second mobile device receives the first RTS signal having a first received RTS power level; and

the second mobile device transmits the first CTS signal having a first transmit CTS power level that is a function of the first received RTS power level.

41. The machine readable medium of claim 40 wherein the function is selected from a group consisting of inversely proportional to the first received RTS power level and monotonically decreasing with the first received RTS power level.

42. The machine readable medium of claim 37 further comprising instructions for:

receiving, at a third mobile device, the first RTS signal from the first mobile device having a second received RTS power level;

receiving, at the third mobile device, a second RTS signal from a fourth mobile device having a third received RTS power level; and

determining, at the third mobile device, whether to transmit a second CTS signal to the fourth mobile device based on a predetermined function of the second received RTS power level and the third received RTS power level.

43. The machine readable medium of claim 42 wherein the predetermined function compares the ratio of the second received RTS power level and the third received RTS power level to a predetermined threshold.

44. The machine readable medium of claim 42 further comprising instructions for:

receiving, at the fourth mobile device, the first CTS signal from the second mobile device, the first CTS signal having a second received CTS power level;

receiving, at the fourth mobile device, the second CTS signal from the third mobile device; and

determining, at the fourth mobile device, whether to transmit a data signal based on a predetermined function of the second received CTS power level.

45. The machine readable medium of claim 44 wherein the predetermined function compares the product of the second received CTS power level and a second transmit data power level to a predetermined threshold.

46. The machine readable medium of claim 45 wherein the second transmit data power level is to be used by the fourth mobile device to transmit a second RTS signal to the third mobile device or a data signal to the third mobile device.

47. The machine readable medium of claim 46 wherein the second transmit data power level is inversely proportional to or monotonically decreasing with a channel gain between the third mobile device and the fourth mobile device.

48. The machine readable medium of claim 47 wherein the channel gain is determined from a prior signal transmitted from the third mobile device to the fourth mobile device.