Method and apparatus for constant envelope orthogonal frequency division multiplexing in a wireless system

• US 20060274641A1
• Filed: 03/31/2006
• Published: 12/07/2006
• Est. Priority Date: 04/04/2005
• Status: Abandoned Application

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Shin, Sung-Hyuk, Marinier, Paul, Briancon, Alain Charles Louis, Chitrapu, Prabhakar R., Zhang, Guodong, Tsai, Yingming, Shah, Yogendra, Grieco, Donald M., Shan, TieJun
• Application Number:
  US11/394,931
• Publication Number:
  US 20060274641A1
• Time in Patent Office: Days
• US Class Current: 370/210
• CPC Class Codes: H04L 27/2003 for continuous phase modulation frequency shift keying H04L27/10
• CPC Class Codes: H04L 27/2614 Peak power aspects

Abstract

In a wireless communication system comprising at least one wireless transmit/receive unit (WTRU), a base station, and a radio network controller (RNC), a method for constant envelope orthogonal frequency division multiplexing (CE-OFDM) modulation comprises the WTRU performing an inverse transform on the data. The WTRU next performs constant envelope (CE) modulation on the data and transmits the CE-OFDM data to the base station. The base station receives the data and CE demodulates the data. The base station performs a transform on the demodulated data.

Claims

1. In a wireless communication system comprising at least one wireless transmit/receive unit (WTRU), a base station, and a radio network controller (RNC), a method for constant envelope orthogonal frequency division multiplexing (CE-OFDM) modulation, the method comprising:

the WTRU performing an inverse transform on data to be transmitted by the WTRU;

the WTRU performing CE modulation on the data and transmitting the CE-OFDM data to the base station;

the base station receiving the data and CE demodulating the data; and

the base station performing a transform on the demodulated data.

2. The method of claim 1, wherein the CE modulation is frequency modulation.

3. The method of claim 2, wherein the frequency modulation is continuous phase frequency shift keying modulation.

4. The method of claim 1, wherein the WTRU clips the data prior to performing CE modulation.

5. The method of claim 4 further comprising jointly determining the clipping level and the modulation index.

6. The method of claim 1, wherein the WTRU quantizes the data prior to performing CE modulation.

7. The method of claim 6, wherein the base station dequantizes the data after CE demodulating the data.

8. The method of claim 1, wherein the WTRU filters the data prior to performing CE modulation.

9. The method of claim 8 wherein the base station performs inverse filtering on the data after performing CE demodulation.

10. The method of claim 8 wherein the WTRU multiplies a scrambling code to the data prior to performing CE modulation.

11. The method of claim 10 wherein the base station multiplies a de-scrambling code to the data after performing CE demodulation.

12. The method of claim 8 wherein the WTRU precodes the data prior to performing CE modulation.

13. The method of claim 12 wherein the base station performs inverse precoding on the data after performing CE demodulation.

14. The method of claim 1, further comprising the WTRU inserting a cyclic prefix to the data prior to performing CE modulation.

15. The method of claim 14, further comprising the base station removing the cyclic prefix from the data after performing CE demodulation.

16. The method of claim 1, further comprising the base station equalizing the data prior to performing CE demodulation.

17. The method of claim 16 wherein the equalizing is time domain equalization.

18. The method of claim 16, further comprising the base station pre-equalizing the data after performing the transform on the demodulated data.

19. The method of claim 18 wherein the pre-equalization is frequency domain equalization.

20. The method of claim 1, further comprising converting the data from a serial data to parallel data prior to the WTRU performing the inverse transform.

21. The method of claim 20 further comprising converting the data from a parallel data to serial data after the base station transforms the data.

22. The method of claim 21, wherein the base station performs post-equalization to the data prior to the parallel to serial conversion, and the base station performs pre-equalization to the data prior to performing CE demodulation.

23. The method of claim 22, further comprising providing decision feedback information from the post-equalization to the pre-equalization step.

24. The method of claim 22, wherein the post equalization is performed by multiple single channel post-equalizers.

25. The method of claim 22, wherein the post-equalization is performed by a single post-multichannel equalizer.

26. The method of claim 22, further comprising providing turbo feedback information for post-equalization and pre-equalization.

27. The method of claim 26 further comprising performing an inverse OFDM transform on the post-equalized data.

28. The method of claim 22, further comprising estimating a frequency offset.

29. The method of claim 28, further comprising synchronizing time.

30. The method of claim 28, further comprising synchronizing frequency.

31. In a wireless communication system comprising at least one wireless transmit/receive unit (WTRU), a base station, and a radio network controller (RNC), a method for constant envelope orthogonal frequency division multiplexing (CE-OFDM) modulation, the method comprising:

performing an inverse transform on data to be transmitted by the WTRU;

pre-estimating the peak to average power ratio (PAPR); and

transmitting the data.

32. The method of claim 31, further comprising constant envelope modulating the data prior to transmitting the data, if the PAPR exceeds a pre-determined threshold.

33. In a wireless communication system comprising at least one wireless transmit/receive unit (WTRU), a base station, and a radio network controller (RNC), a method for constant envelope orthogonal frequency division multiplexing (CE-OFDM) modulation, the method comprising:

performing an inverse transform on data to be transmitted by the WTRU;

selecting a transmission system depending on a pathloss value between the WTRU and the base station; and

transmitting the data utilizing the selected transmission system.

34. The method of claim 33 wherein the transmission system implements at least one of CE-OFDM and OFDM.

35. The method of claim 34 wherein the pathloss between the WTRU and the base station equals or exceeds a predetermined threshold value and the selected transmission system is CE-OFDM.

36. The method of claim 35 wherein the RNC monitors the pathloss between the WTRU and the base station and transmits a signal to the WTRU through the base station for the WTRU to utilize CE-OFDM.

37. The method of claim 35 wherein all WTRUs in the wireless communication system utilize CE-OFDM.

38. The method of claim 34 wherein the pathloss between the WTRU and the base station is less than a predetermined threshold and the selected transmission system is OFDM.

39. The method of claim 38 wherein the RNC monitors the pathloss between the WTRU and the base station and transmits a signal to the WTRU through the base station for the WTRU to utilize OFDM.

40. The method of claim 38 wherein all WTRUs in the wireless communication system utilize OFDM.

41. The method of claim 34 wherein at least one WTRU utilizes CE-OFDM and at least one WTRU utilizes OFDM.

42. The method of claim 41 wherein the at least one WTRU utilizing CE-OFDM transmits on a different frequency than the at least one WTRU utilizing OFDM.

43. The method of claim 41 wherein the at least one WTRU utilizing CE-OFDM and the at least one WTRU utilizing OFDM transmit at different times.

44. A wireless transmit/receive unit (WTRU), comprising:

an inverse transform device;

a constant envelope modulation (CEM) device in communication with the inverse transform device; and

a transmitter in communication with the CEM device.

45. The WTRU of claim 44, further comprising a clipping device in communication with the inverse transform device and the CEM device.

46. The WTRU of claim 44, further comprising a quantization device in communication with the inverse transform device and the CEM device.

47. The WTRU of claim 44, further comprising a filtering device in communication with the inverse transform device and the CEM device.

48. The WTRU of claim 44, further comprising a cyclic prefix insertion device in communication with the inverse transform device and the CEM device.

49. The WTRU of claim 44, further comprising a pre-estimate PAPR device in communication with the inverse transform device and the CEM device.

50. The WTRU of claim 44, further comprising a pre-estimate PAPR device in communication with the inverse transform device and the transmitter.

51. The WTRU of claim 44, further comprising a serial to parallel converter in communication with the inverse transform device.

52. A base station comprising:

a receiver;

a constant envelope (CE) demodulation device in communication with the receiver; and

a transform device in communication with the CE demodulation device.

53. The base station of claim 52, further comprising a dequantization device in communication with the CE demodulation device and the transform device.

54. The base station of claim 52, further comprising an inverse filtering device in communication with the CE demodulation device and the transform device.

55. The base station of claim 52, further comprising a cyclic prefix removal device in communication with the CE demodulation device and the transform device.

56. The base station of claim 52, further comprising a pre-equalizer in communication with the receiver and the CE demodulation device.

57. The base station of claim 56 wherein the pre-equalizer is a time-domain equalizer.

58. The base station of claim 56, further comprising a post-equalizer in communication with the transform device.

59. The base station of claim 58 wherein the post-equalizer is a frequency domain equalizer.

60. The base station of claim 58 wherein the post-equalizer comprises a one-tap channel estimation equalizer.

61. The base station of claim 58 wherein the post-equalizer comprises a post-multi-channel equalizer.

62. The base station of claim 58 wherein the post-equalizer comprises at least one multiple single channel post-equalizer.

63. The base station of claim 58, further comprising a parallel to serial converter in communication with the post-equalizer.

64. The base station of claim 63, further comprising a turbo receiver in communication with the post-equalizer and the parallel to serial converter.

65. The base station of claim 64, further comprising an inverse transform device in communication with the turbo receiver and the pre-equalizer.

66. The base station of claim 58, further comprising a frequency offset estimator in communication with the CE demodulation device and the pre-equalizer.