Randomly changing pulse polarity and phase in an UWB signal for power spectrum density shaping

• US 7,298,792 B2
• Filed: 03/14/2005
• Issued: 11/20/2007
• Est. Priority Date: 02/10/2003
• Status: Expired due to Term

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Zhang, Jinyun, Molisch, Andreas F., Nakache, Yves-Paul
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US11/079,305
• Publication Number:
  US 20050175068A1
• Time in Patent Office: 981 Days
• Field of Search: 375/295, 375/138, 375/146, 375/130, 375/242, 375/259, 375/260, 375/239, 375/238, 375/302, 375/324, 375/340
• US Class Current: 375/295
• CPC Class Codes: H04B 1/71632 Signal aspects H04B1/7172 and H04B1/7176 take precedence
• CPC Class Codes: H04B 1/7176 Data mapping, e.g. modulation
• CPC Class Codes: H04B 1/719 Interference-related aspects
• CPC Class Codes: H04B 2001/6908 using time hopping
• CPC Class Codes: H04L 25/03866 using scrambling

Abstract

A method and system eliminate spectral lines and shapes the power spectral density of an ultra bandwidth signal. First, a train of non-periodic pulses is generated. The non-periodic pulses are then modulated in time according to uncorrelated symbols. A polarity of the non-periodic pulses is inverted randomly before transmitting the non-periodic pulses as an ultra wide bandwidth signal to eliminate spectral lines and to shape a power spectral density of the ultra wide bandwidth signal.

Claims

1. A method for eliminating spectral lines and shaping a power spectral density of an ultra wide bandwidth signal, comprising:

generating a train of non-periodic pulses;

modulating the non-periodic pulses in time according to uncorrelated symbols; and

inverting, randomly, a polarity of the non-periodic pulses before transmitting the non-periodic pulses as an ultra wide bandwidth signal to eliminate spectral lines and to shape a power spectral density of the ultra wide bandwidth signal.

2. The method of claim 1 wherein each uncorrelated symbol includes one uncorrelated pulse.

3. The method of claim 2 wherein the modulation of the one uncorrelated pulse per uncorrelated symbol is pulse position modulation.

4. The method of claim 2 wherein the modulation of the one uncorrelated pulse per uncorrelated symbol is amplitude modulation.

5. The method of claim 2 wherein the modulation of the one uncorrelated pulse per uncorrelated symbol is a combination of amplitude modulation and pulse position modulation.

6. The method of claim 4 wherein the amplitude modulation is accomplished with on/off keying, wherein for every time period a zero is represented by a non-periodic pulse, and a one by no pulse.

7. The method of claim 1 wherein each uncorrelated symbol includes a combination of individual non-periodic pulses.

8. The method of claim 7 wherein the polarity of a combination of N non-periodic pulses of each uncorrelated symbol is randomly and independently inverted from uncorrelated symbol to uncorrelated symbol.

9. The method of claim 7 wherein the polarity of individual non-periodic pulses of each uncorrelated symbol are randomly and independently inverted within each uncorrelated symbol and from uncorrelated symbol to uncorrelated symbol.

10. The method of claim 7 wherein the polarity of individual non-periodic pulses of each uncorrelated symbol are randomly inverted within each uncorrelated symbol and identically inverted from uncorrelated symbol to uncorrelated symbol.

11. The method of claim 7 wherein the uncorrelated symbols are modulated by pulse position modulation.

12. The method of claim 7 where the uncorrelated symbols are modulated by amplitude modulation.

13. The method of claim 7 wherein the uncorrelated symbols are modulated by a combination of pulse position modulation and amplitude modulation.

14. The method of claim 7 wherein the combination of non-periodic pulses follows a pattern of a time hopping sequence.

15. The method of claim 7 wherein a combination of non-periodic pulses is according to a pattern of a direct sequence spread spectrum.

16. The method of claim 7 wherein different non-periodic pulses sequences are codewords used as uncorrelated symbols of a modulation format.

17. The method of claim 16 wherein the modulation format is M-ary orthogonal keying and M-ary bi-orthogonal keying.

18. The method of claim 1 further comprising:

shaping a spectrum of the UWB signal to a predetermined shape by the random inverting of the polarity of the non-periodic pulses.

19. The method of claim 18 wherein the modulation is pulse amplitude modulation.

20. The method of claim 18 wherein the modulation is pulse position modulation.

21. The method of claim 18 wherein the modulation is a combination of pulse amplitude modulation and pulse position modulation.

22. The method of claim 18 wherein the modulation uses codewords.

23. The method of claim 18 wherein the modulation is a M-ary orthogonal keying modulation.

24. The method of claim 7 further comprising:

shaping a spectrum of the UWB signal to a predetermined shape by the random inverting of the polarity of the non-periodic pulses.

25. The method of claim 24 wherein the modulation is pulse amplitude modulation.

26. The method of claim 24 wherein the modulation is pulse position modulation.

27. The method of claim 24 wherein the modulation is a combination of pulse amplitude modulation and pulse position modulation.

28. The method of claim 9 further comprising:

shaping a spectrum of the UWB signal to a predetermined shape by the random inverting of the polarity of the non-periodic pulses.

29. The method of claim 14 further comprising:

shaping a spectrum of the UWB signal to a predetermined shape by the random inverting of the polarity of the non-periodic pulses.

30. The method of claim 1 further comprising:

grouping sets of non-periodic pulses into subwaveforms; and

means for inverting randomly a polarity of the subwaveforms.

31. The method of claim 30 further comprising:

shaping a spectrum of the UWB signal to a predetermined shape by the random inverting of the polarity of the subwaveforms.

32. The method of claim 30 further comprising:

shaping a spectrum of the ultra wide band signal to a predetermined shape by the random inverting of the polarity of a set of subwaveforms of N-tuplets of non-periodic pulses using a transmit references scheme to carry information.

33. The method of claim 2 further comprising:

grouping sets of uncorrelated symbols;

means for inverting, randomly, a polarity of the uncorrelated symbols a first set of the sets of uncorrelated symbols; and

means for inverting a polarity of a next set of the sets of uncorrelated symbols according to the polarity of the uncorrelated symbols of the first set.

34. The method of claim 1 wherein each uncorrelated symbol includes subwaveforms composed of a combination of non-periodic pulses with a sequence of polarities that depends on the data.

35. The method of claim 1, in which the modulating is according a sub part of the uncorrelated symbol.

36. The method of claim 1, in which the modulating is according to a group of uncorrelated symbols.

37. The method of claim 35, in which the sub part of the uncorrelated symbol includes chips of a spreading sequence.

38. The method of claim 35, in which the sub part of the uncorrelated symbol includes elements of codewords.

39. The method of claim 1 further comprising:

randomizing a phase of the non-periodic pulses to shape a spectrum of the UWB signal.

40. A system for eliminating spectral lines and shaping the spectrum of an ultra wide bandwidth signal, comprising:

means for generating a train of non-periodic pulses;

means for modulating the non-periodic pulses in time according to uncorrelated symbols; and

means for inverting, randomly, a polarity of the non-periodic pulses before transmitting the non-periodic pulses as an ultra wide bandwidth signal to eliminate spectral lines and to shape a power spectral density of the ultra wide bandwidth signal.