Pulse shaper design for ultra-wideband communications

• US 7,738,545 B2
• Filed: 09/29/2004
• Issued: 06/15/2010
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Yang, Liuqing, Luo, Xiliang, Giannakis, Georgios B.
• Primary Examiner(s): Payne; David C
• Assistant Examiner(s): Wong; Linda
• Application Number:
  US10/952,713
• Publication Number:
  US 20050105594A1
• Time in Patent Office: 2,085 Days
• Field of Search: 375229-236
• US Class Current: 375/229
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 1/7172 Pulse shape in general H04L25/03834
• CPC Class Codes: H04B 1/7174 Pulse generation in general H04L25/03834
• CPC Class Codes: H04B 1/719 Interference-related aspects

Abstract

The invention provides an ultra-wideband (UWB) transmitter and various techniques for generating digitally filtered UWB pulses that substantially maximize power and bandwidth in one or more frequency bands while allowing narrow-band interference (NBI) to be avoided, e.g. interference to and from wireless local area networks (WLANs). In particular, the UWB transmitter utilizes a digital filter to generate digitally filtered UWB pulses to substantially maximize power and bandwidth in the Federal Communications Commission (FCC) spectral mask for UWB communications. In one embodiment, the invention provides a method comprising generating digitally filtered ultra-wide band (UWB) pulses to substantially maximize power in one or more frequency bands of a UWB spectrum and to substantially reduce power in one or more NBI frequency bands of the UWB spectrum. The invention may be implemented without modifying the analog components of existing UWB transmitters.

Claims

1. A method comprising generating digitally filtered ultra-wide band (UWB) pulses to substantially maximize power in one or more frequency bands of a UWB spectrum and to substantially reduce power in one or more narrow band interference (NBI) frequency bands of the UWB spectrum, wherein generating the digitally filtered UWB pulses comprises:

generating a stream of information bearing symbols;

selecting spacing of a set of tap coefficients of a digital filter, the digital filter being included within a UWB transmitter;

selecting the set of tap coefficients based on the one or more frequency bands;

digitally filtering the stream of information bearing symbols according to the set of selected tap coefficients; and

generating, by the UWB transmitter, the digitally filtered UWB pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-n<br><br><br><br>T_0\right),$

where w[n] represents the n^th tap coefficient, T₀ represents the spacing of the coefficients, M represents the number of tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

2. The method of claim 1, further comprising generating digitally filtered UWB pulses to substantially maximize bandwidth in the one or more frequency bands of the UWB spectrum.

3. The method of claim 1, wherein g(t) represents a Gaussian monocycle.

4. The method of claim 1, wherein the set of tap coefficients are selected according to a Parks-McClellan algorithm.

5. The method of claim 1, wherein the set of tap coefficients are selected according to the following equation:

$\underset{{\left\{w_0<br><br>\left[n\right]\right\}}_{n=0}^L}{\min }<br><br>\left\{\underset{F\in <br><br>\mathrm{\zeta <br><br>}}{\max }<br><br>\left|e<br><br>\left(F\right)\right|\right\},$

where {w₀[n]}_n=0^L represents the set of tap coefficients, w₀[n] represents the n^th tap coefficient, e(F) represents an error function that approximates error between the one or more frequency bands and an approximation of the one or more frequency bands and is a function of the frequency of the UWB pulses F, and ζ

represents the union of disjoint intervals in the one or more frequency bands.

6. The method of claim 1, wherein the one or more frequency bands of the UWB spectrum comprise at least one of frequency bands within a Federal Communications Commission (FCC) spectral mask for the UWB spectrum, a frequency sub-band of the UWB spectrum, and at least two frequency sub-bands of the UWB spectrum.

7. The method of claim 1, wherein the one or more NBI frequency bands comprise a governmentally licensed frequency band within the UWB spectrum.

8. The method of claim 1, wherein the one or more NBI frequency bands comprise at least one of a 5 GHz frequency band, a frequency band including wireless communications from wireless local area networks (WLAN), a frequency band having heavy traffic, and a frequency band including co-existing wireless communication systems.

9. The method of claim 1, further comprising generating the digitally filtered UWB pulses according to a frequency hopping (FH) scheme, including substantially maximizing power of at least a portion of a given one of the pulses when the given one of the pulses falls within a selected FH frequency band and reducing the power of the given one of the pulses when the given one of the pulses falls outside the selected FH frequency band.

10. The method of claim 1, wherein the digitally filtered UWB pulses substantially maximize power and bandwidth in a Federal Communications Commission (FCC) spectral mask for the UWB spectrum while reducing power in a 5 GHz frequency band.

11. A digital filter of an ultra-wideband (UWB) transmitter that generates digitally filtered UWB pulses to substantially maximize power in one or more frequency bands of a UWB spectrum and to substantially reduce power in one or more narrow band interference (NBI) frequency bands of the UWB spectrum, wherein the digital filter generates the digitally filtered UWB pulses at least by:

adaptively selecting a set of tap coefficients based on the one or more frequency bands;

digitally filtering a stream of information bearing symbols according to the selected set of tap coefficients; and

generating the digitally filtered UWB pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-{\mathrm{nT}}_0\right),$

where w[n] represents a n^th tap coefficient, T₀ represents spacing of the coefficients, M represents a number of the tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

12. The digital filter of claim 11, wherein the digital filter generates the digitally filtered UWB pulses to substantially maximize bandwidth in the one or more frequency bands of the UWB spectrum.

13. The digital filter of claim 11, wherein g(t) represents a Gaussian monocycle.

14. The digital filter of claim 11, wherein the one or more NBI frequency bands comprise a governmentally licensed frequency band within the UWB spectrum.

15. The digital filter of claim 11, wherein the one or more NBI frequency bands comprise at least one of a 5 GHz frequency band, a frequency band including wireless communications from wireless local area networks (WLAN), a frequency band having heavy traffic, and a frequency band including co-existing wireless communication systems.

16. The digital filter of claim 11, wherein the digital filter digitally filters the UWB pulses such that an effective shape of the pulses following conversion to analog and analog shaping substantially exploits allocated power and frequency defined by a governmentally regulated mask associated with UWB communication.

17. The digital filter of claim 11, wherein the one or more narrow band interference (NBI) frequency bands comprise unlicensed frequency bands that include interference.

18. The digital filter of claim 11, wherein the digital filter digitally filters a plurality of UWB pulses according to a frequency hopping scheme, including reducing power of at least a portion of a given one of the pulses when the given one of the pulses falls within one or more governmentally regulated frequency bands.

19. The digital filter of claim 11, wherein the digital filter digitally filters the UWB pulses according to a frequency hopping (FH) scheme, including substantially maximizing power of at least a portion of a given one of the pulses when the given one of the pulses falls within a selected FH frequency band and reducing the power of the given one of the pulses when the given one of the pulses falls outside the selected frequency band.

20. The digital filter of claim 11, wherein the digitally filtered UWB pulses substantially maximize power and bandwidth in a Federal Communications Commission (FCC) spectral mask for the UWB spectrum while reducing power in a 5 GHz frequency band.

21. The digital filter of claim 11, wherein the digital filter comprises a shift register, wherein the shift register stores the set of tap coefficients.

22. The digital filter of claim 19, wherein the digital filter comprises a set of shift registers, each of the shift registers storing a set of tap coefficients for a selected frequency band of a frequency hopping (FH) scheme.

23. An ultra-wideband (UWB) transmitter comprising:

a symbol generator that generates a stream of information bearing symbols;

a digital filter that digitally filters the stream of information bearing symbols according to a set of tap coefficients to substantially maximize power in one or more frequency bands of a UWB spectrum and to substantially reduce power in one or more narrow band interference (NBI) frequency bands of the UWB spectrum, wherein the digital filter;

selects spacing of the set of tap coefficients;

selects the set of tap coefficients based on the one or more frequency bands; and

digitally filters the stream of information bearing symbols according to the selected set of tap coefficients;

a timer that processes the stream of information bearing symbols in accordance with a pulse position modulation (PPM) scheme; and

a pulse generator that generates digitally filtered ultra-wideband (UWB) pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-{\mathrm{nT}}_0\right),$

where w[n] represents an n^th tap coefficient, T₀ represents spacing of the coefficients, M represents a number of the tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

24. The UWB transmitter of claim 23, wherein the digital filter digitally filters the stream of information bearing symbols to substantially maximize bandwidth in the one or more frequency bands of the UWB spectrum.

25. The UWB transmitter of claim 23, wherein g(t) represents a Gaussian monocycle.

26. The UWB transmitter of claim 23, wherein the digital filter digitally filters the UWB pulses such that an effective shape of the pulses following conversion to analog and analog shaping substantially exploits allocated power and frequency defined by a governmentally regulated mask associated with ultrawide band (UWB) communication.

27. The UWB transmitter of claim 23, wherein the one or more NBI frequency bands comprise a governmentally licensed frequency band within the UWB spectrum.

28. The UWB transmitter of claim 23, wherein the one or more NBI frequency bands comprise at least one of a 5 GHz frequency band, a frequency band including wireless communications from wireless local area networks (WLAN), a frequency band having heavy traffic, and a frequency band including co-existing wireless communication systems.

29. The UWB transmitter of claim 23, wherein the one or more NBI frequency bands comprise a non-licensed frequency band within the UWB spectrum that includes substantial interference.

30. The UWB transmitter of claim 23, wherein the digital filter digitally filters a plurality of UWB pulses according to a frequency hopping scheme, including reducing power of at least a portion of a given one of the pulses when the given one of the pulses falls within one or more governmentally regulated frequency bands.

31. The UWB transmitter of claim 23, wherein the digital filter digitally filters the stream of information bearing symbols according to a frequency hopping (FH) scheme, including substantially maximizing power of at least a portion of a given one of the pulses when the given one of the pulses falls within the selected FH frequency band and reducing the power of the given one of the pulses when the given one of the pulses falls outside the selected FH frequency band.

32. The UWB transmitter of claim 23, wherein the digitally filtered UWB pulses substantially maximize power and bandwidth in a Federal Communications Commission (FCC) spectral mask for the UWB spectrum.

33. The UWB transmitter of claim 23, wherein the digital filter comprises a shift register, wherein the shift register stores the set of tap coefficients.

34. The UWB transmitter of claim 31, wherein the digital filter comprises a set of shift registers, each of the shift registers storing a set of tap coefficients for a selected frequency band of a frequency hopping (FH) scheme.

35. A method comprising digitally filtering ultrawide band (UWB) pulses to reduce power in one or more narrow band interference (NBI) frequency bands of a governmentally defined UWB spectrum, wherein digitally filtering the UWB pulses comprises:

selecting spacing of a set of tap coefficients of a digital filter, the digital filter being included within a UWB transmitter;

selecting the set of tap coefficients based on one or more frequency bands of the UWB spectrum;

digitally filtering a stream of information bearing symbols according to the set of selected tap coefficients; and

digitally filtering, by the UWB transmitter, the UWB pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-{\mathrm{nT}}_0\right),$

where w[n] represents the n^th tap coefficient, T₀ represents the spacing of the coefficients, M represents the number of tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

36. The method of claim 35, further comprising digitally filtering the UWB pulses to substantially maximize power in the one or more frequency bands of the UWB spectrum.

37. The method of claim 35, further comprising digitally filtering the UWB pulses such that an effective shape of the pulses following conversion to analog and analog shaping substantially exploits allocated power and frequency defined by a governmentally regulated mask associated with UWB communication.

38. The method of claim 37, wherein the analog shaping comprises Gaussian pulse shaping.

39. The method of claim 35, wherein the one or more NBI frequency bands comprise governmentally regulated frequency bands that a government licenses.

40. The method of claim 35, wherein the one or more NBI frequency bands comprise unlicensed frequency bands that include interference.

41. The method of claim 35, further comprising digitally filtering a plurality of UWB pulses according to a frequency hopping scheme, including reducing power of at least a portion of a given one of the pulses when the given one of the pulses falls within one or more of the governmentally regulated frequency bands.

42. A digital filter of an ultrawide band (UWB) transmitter that digitally filters a plurality of UWB pulses to reduce power in one or more narrow band interference (NBI) frequency bands of a governmentally defined UWB spectrum, wherein the digital filter generates the digitally filtered UWB pulses at least by:

adaptively selecting a set of tap coefficients based on one or more frequency bands of the UWB spectrum;

digitally filtering a stream of information bearing symbols according to the selected set of tap coefficients; and

generating the digitally filtered UWB pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-{\mathrm{nT}}_0\right),$

where w[n] represents the n^th tap coefficient, T₀ represents the spacing of the coefficients, M represents the number of tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

43. The digital filter of claim 42, wherein the digital filter digitally filters the UWB pulses to substantially maximize power in the one or more frequency bands of the UWB spectrum.

44. The digital filter of claim 42, wherein the digital filter digitally filters the UWB pulses such that an effective shape of the pulses following conversion to analog and analog shaping substantially exploits allocated power and frequency defined by a governmentally regulated mask associated with UWB communication.

45. The digital filter of claim 42, wherein the one or more narrow band interference (NBI) frequency bands comprise governmentally regulated frequency bands that a government licenses.

46. The digital filter of claim 42, wherein the one or more narrow band interference (NBI) frequency bands comprise unlicensed frequency bands which include interference.

47. The digital filter of claim 42, wherein the digital filter digitally filters the UWB pulses according to a frequency hopping scheme, including reducing power of at least a portion of a given one of the pulses when the given one of the pulses falls within one or more of the governmentally regulated frequency bands.

48. An ultrawide band (UWB) transmitter including a digital filter that digitally filters a plurality of UWB pulses to reduce power in one or more narrow band interference (NBI) frequency bands of a governmentally defined UWB spectrum, wherein the digital filter:

selects spacing of a set of tap coefficients;

selects the set of tap coefficients based on one or more frequency bands of the UWB spectrum; and

digitally filters a stream of information bearing symbols according to the selected set of tap coefficients,

wherein the digital filter digitally filters the UWB pulses based on the following equation;

$p<br><br>\left(t\right)=\underset{n=0}{\overset{M-1}{\sum <br><br>}}<br><br><br><br>w<br><br>\left[n\right]<br><br>g<br><br>\left(t-{\mathrm{nT}}_0\right),$

where w[n] represents the n^th tap coefficient, T₀ represents the spacing of the coefficients, M represents the number of tap coefficients, g(t) represents analog pulse shaping, and p(t) represents the digitally filtered UWB pulses.

49. The UWB transmitter of claim 48, wherein the digital filter digitally filters the UWB pulses to substantially maximize power in the one or more frequency bands of the UWB spectrum.

50. The UWB transmitter of claim 48, wherein the digital filter digitally filters the UWB pulses such that an effective shape of the pulses following conversion to analog and analog shaping substantially exploits allocated power and frequency defined by a governmentally regulated mask associated with UWB communication.

51. The UWB transmitter of claim 48, wherein the one or more NBI frequency bands comprise governmentally regulated frequency bands that a government licenses.

52. The UWB transmitter of claim 48, wherein the one or more NBI frequency bands comprise unlicensed frequency bands that include interference.

53. The UWB transmitter of claim 48, wherein the digital filter digitally filters the UWB pulses according to a frequency hopping scheme, including reducing power of at least a portion of a given one of the pulses when the given one of the pulses falls within one or more of the governmentally regulated frequency bands.