Method for transmit pulse design for ultra-wideband communications

• US 7,489,720 B2
• Filed: 11/04/2003
• Issued: 02/10/2009
• Est. Priority Date: 11/04/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hinton, Danielle Ayodele, Batra, Anuj, Dabak, Anand G.
• Primary Examiner(s): Lugo; David B
• Application Number:
  US10/700,723
• Publication Number:
  US 20040109506A1
• Time in Patent Office: 1,925 Days
• Field of Search: 375/242, 375/130, 375/138
• US Class Current: 375/138
• CPC Class Codes: H04B 1/7172 Pulse shape in general H04L25/03834
• CPC Class Codes: H04B 1/719 Interference-related aspects

Abstract

Method for designing transmission pulses for ultra-wideband communications systems. A preferred embodiment comprises specifying a spectral description for the pulse. After a spectral description is created, then an approximation of the pulse can be created and well known optimization techniques, such as the least squares technique, can be used to minimize the difference between the approximation and the pulse. If the communications system is operating in the presence of interferers, then the spectral mask can be modified to ensure that the approximation carries no signal information in frequencies corresponding to the interferers.

Claims

1. A method for transmitting a pulse, the method comprising:

forming a quantized representation of the pulse, wherein the forming comprises

specifying a spectral mask for the pulse,

applying an optimization routine to compute samples of the quantized representation of the pulse, wherein the optimization routine minimizes a difference between the quantized representation of the pulse and the pulse, and

storing the samples of the quantized representation of the pulse.

2. The method of claim 1 further comprising after the specifying, stating a number of samples in the quantized representation of the pulse.

3. The method of claim 1, wherein the spectral mask for the pulse specifies a frequency domain response for the pulse.

4. The method of claim 3, wherein the spectral mask specifies a non-zero portion in frequency bands of the pulse where the pulse is to carry information and an essentially zero portion in frequency bands of the pulse where the pulse is to not carry information.

5. The method of claim 4, wherein the non-zero portion has a positive value.

6. The method of claim 4, wherein the spectral mask can specify an essentially zero portion within a non-zero portion.

7. The method of claim 6, wherein the spectral mask can specify a plurality of essentially zero portions within a non-zero portion.

8. The method of claim 1, wherein the optimization treats the spectral mask as a desired frequency response for a filter and the filter'"'"'s taps are the samples of the quantized representation of the pulse.

9. The method of claim 1, wherein the pulse is a wide-bandwidth pulse for use in an ultra-wideband communications system.

10. The method of claim 1, wherein the pulse is an ideal rectangular pulse.

11. The method of claim 1, further comprising transmitting the pulse.

12. A method for transmitting a pulse, the method comprising:

forming a quantized representation of the pulse, wherein the forming comprises

specifying a spectral mask for the pulse, and

applying an optimization routine to compute samples of the quantized representation of the pulse, wherein the optimization routine minimizes a difference between the quantized representation of the and the pulse and treats the spectral mask as a desired frequency response for a filter and the filter'"'"'s taps are samples of the quantized representation of the pulse, wherein the optimization comprises;

writing a finite length approximation of the pulse, wherein the finite length is a number of samples of the pulse,

determining an error function between the pulse and the finite length approximation of the pulse,

applying the optimization routine to minimize the error function, and

storing the samples of the quantized representation of the pulse.

13. The method of claim 12, wherein the optimization routine uses the least squares error minimization.

14. The method of claim 13, wherein the pulse is an infinite length sinc function expressible in the frequency domain as H_i(ω

), wherein the finite length approximation of the pulse is expressible in the frequency domain as

$H<br><br>\left(\mathrm{\omega <br><br>}\right)=\underset{n=0}{\overset{N}{\sum <br><br>}}<br><br>h<br><br>\left(n\right)<br><br>{\mathrm{e<br><br>}}^{-j<br><br><br><br>\mathrm{\omega <br><br>}<br><br><br><br>n},$

and the error function is expressible as

$\mathrm{Error}=\underset{m=-N/2}{\overset{m=N/2}{\sum <br><br>}}<br><br>{<br><br>h_m-{\left(h_i\right)}_m<br><br>}^2+\underset{m=N/2+1}{\overset{L-1}{\sum <br><br>}}<br><br>{<br><br>{\left(h_i\right)}_m<br><br>}^2$

where N+1 is the length of the finite length approximation of the pulse and L is an integer number.

15. The method of claim 12 further comprising after the determining, using a weighting function to place additional optimization emphasis on certain portions of the spectral mask.

16. The method of claim 15, wherein the weighting function is a positive value function, and wherein a larger value for the weighting function places additional optimization emphasis.

17. The method of claim 16, wherein the values of the weighting functions are non-zero positive integers, and wherein if no additional optimization emphasis is desired in a certain portion of the spectral mask, then an integer one is set for the value of the weighting function in the certain portion.

18. The method of claim 17, wherein large values of the weighting function are used in portions of the spectral mask where it is desired that the pulse is not to carry information.

19. The method of claim 16, wherein when the length of the finite length approximation is large, then the weighting function is not used.

20. The method of claim 16, wherein when the length of the finite length approximation is small, then additional importance is placed upon the values of the weighting function.

21. The method of claim 12, further comprising transmitting the pulse.

22. A method for transmitting a pulse to mitigate interference comprising:

determining the presence of interferers;

specifying a spectral mask for the pulse, wherein the spectral mask is used to describe a frequency response of the pulse, and wherein if the interferers occupy a portion of the spectral mask intended to carry signal, then portions of the spectral mask corresponding to frequencies of the interferers are set to carry significantly less signal than portions corresponding to frequencies intended to carry signal;

computing the pulse based on the spectral mask, wherein the computing comprises applying an optimization routine to compute a quantized representation of the pulse, wherein the optimization routine minimizes a difference between the quantized representation of the pulse and the pulse; and

providing the pulse to an antenna.

23. The method of claim 22, wherein the portions corresponding to frequencies of the interferers are set to carry no signal.

24. The method of claim 22, wherein the portions corresponding to frequencies of the interferers are set to carry at least 8 dB less signal than portions corresponding to frequencies intended to carry signals.

25. The method of claim 22, wherein an amount of difference in the signal carried in the portions corresponding to frequencies of the interferers and the portions corresponding to frequencies intended to carry signals can be dependent upon a measured magnitude of the interferers.

26. The method of claim 22, wherein the portions corresponding to the frequencies intended to carry signal are larger in frequency than the frequencies of the interferers.

27. The method of claim 22, wherein the pulse is a wide-bandwidth pulse for use in an ultra-wideband communications system, and wherein the determining comprises scanning a frequency band essentially equal to a frequency band of the pulse for the presence of interferers.

28. The method of claim 27, wherein the scanning occurs during an initial power on sequence.

29. The method of claim 27, wherein the scanning occurs when performance falls below a specified threshold.

30. The method of claim 22, wherein the pulse is a wide-bandwidth pulse for use in an ultra-wideband communications system, and wherein the determining comprises using frequencies associated with a list of electronic equipment operating in close proximity as identified interferers.

31. The method of claim 30, wherein the list is entered during equipment installation.

32. The method of claim 22, wherein a quantized version of the pulse can be stored and then subsequently retrieved when there is a need to transmit the pulse.

33. A method for transmitting a pulse to mitigate interference comprising:

determining the presence of interferers wherein the pulse is a wide-bandwidth pulse for use in an ultra-wideband communications system, and wherein the determining comprises scanning a frequency band essentially equal to a frequency band of the pulse for the presence of interferers, wherein the scanning occurs when a received signal strength indicator (RSSI) measurement is high while an error rate measurement is also high;

specifying a spectral mask for the pulse, wherein the spectral mask is used to describe a frequency response of the pulse, and wherein if the interferers occupy a portion of the spectral mask intended to carry signal, then portions of the spectral mask corresponding to frequencies of the interferers are set to carry significantly less signal than portions corresponding to frequencies intended to carry signal;

computing the pulse based on the spectral mask; and

providing the pulse to an antenna.

34. The method of claim 33, wherein the error rate measurement is a packet error rate (PER).

35. A method of transmitting a pulse comprising:

computing samples of a pulse, wherein computing comprises applying an optimization routine to compute a quantized representation of the pulse, wherein

the optimization routine minimizes a difference between the quantized representation of the pulse and the pulse, and

the pulse has a variation of more than a specified value across its pass band;

creating a representation of a sample of the pulse based upon information about the samples;

providing the representation to an antenna to transmit the representation of the sample; and

repeating the creating and providing until all samples of the pulse have been transmitted.

36. The method of claim 35, wherein there is more than one variation across the pulse'"'"'s pass band.

37. The method of claim 35, wherein the information about the sample is retrieved from a memory.

38. The method of claim 35, wherein the information about the sample is preprogrammed into a circuit used to create the representation of the sample.

39. The method of claim 35, wherein the representation is a voltage drop.

40. The method of claim 35, wherein the representation is a current.

41. The method of claim 35, wherein the specified value is based on the type of interferer.