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

• US 20050175068A1
• Filed: 03/14/2005
• Published: 08/11/2005
• Est. Priority Date: 02/10/2003
• Status: Active Grant

• 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
• Granted Patent: US 7,298,792 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• 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 eliminates spectral lines and shapes the power spectral density of an ultra bandwidth signal. First, a train of pulses is generated. The pulses are then modulated in time according to symbols. A polarity of the pulses is inverted randomly before transmitting the pulses as an 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 pulses;

modulating the pulses in time according to symbols; and

inverting, randomly, a polarity of the pulses before transmitting the 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 symbol includes one pulse.

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

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

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

6. The method of claim 3 wherein the pulse amplitude modulation is accomplished with on/off keying, wherein for every time period a zero is represented by a pulse, and a one by no pulse.

7. The method of claim 1 wherein each symbol includes a combination of individual pulses.

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

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

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

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

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

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

14. The methods of claims 7 wherein the combination of pulses follows a pattern of a time hopping sequence.

15. The methods of claims 7 wherein a combination of pulses is according to a pattern of a direct sequence spread spectrum.

16. The method of claim 7 wherein different pulses sequences are codewords used as 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 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 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 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 pulses.

30. The method of claim 1 further comprising:

grouping sets of 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 pulses using a transmit references scheme to carry information.

33. The method of claim 2 further comprising:

grouping sets of symbols;

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

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

34. The method of claim 1 wherein each symbol includes subwaveforms composed of a combination of 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 symbol.

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

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

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

39. The method of claim 1 further comprising:

randomizing a phase of the 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 pulses;

means for modulating the pulses in time according to symbols; and

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