Transmit-rake apparatus in communication systems and associated methods

• US 20060088081A1
• Filed: 10/22/2004
• Published: 04/27/2006
• Est. Priority Date: 10/22/2004
• Status: Abandoned Application

• Current Assignee: Alereon Incorporated (PNG Telecommunications, Inc.)
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Fullerton, Larry W., Roberts, Mark, Richards, James, Withington, Paul
• Application Number:
  US10/971,429
• Publication Number:
  US 20060088081A1
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04B 1/71635 Transmitter aspects H04B1/7174 takes precedence
• CPC Class Codes: H04B 1/7172 Pulse shape in general H04L25/03834
• CPC Class Codes: H04B 2001/6908 using time hopping

Abstract

A transmit-rake apparatus includes at least one pulse generator that provides a plurality of pulses with selected signal properties so as to improve the signal-to-noise ratio at a receiver. The signal properties may include pulse timing, amplitude, polarity, and pulse shape. The transmit-rake apparatus may use a multipath analyzer, receive multipath or signal-quality information, or use a combination of those techniques. The multipath analyzer may include a scanning receiver to generate a scan of the multipath response. Correlation of the multipath response with a model pulse shape may be used to establish pulse position and amplitude. Iteration based on link performance measurements may be used to select or refine pulse properties. A method is disclosed to vary the selection of pulses to improve the spectrum.

Claims

1. A transmit-rake apparatus, comprising:

an antenna configured to radiate electromagnetic energy into a medium for reception by a receiver; and

at least one pulse generator coupled to the antenna, the at least one pulse generator configured to provide to the antenna a plurality of pulses having individual signal properties selected so as to improve the signal-to-noise ratio at the receiver.

2. The apparatus of claim 1, wherein the signal properties include pulse timing.

3. The apparatus of claim 1 wherein the signal properties include pulse amplitude.

4. The apparatus of claim 1 wherein the signal properties include pulse polarity.

5. The apparatus of claim 1 wherein the signal properties include pulse shape.

6. The apparatus of claim 1, wherein the pulse generator selects the polarity of each pulse in the plurality of pulses.

7. The apparatus of claim 1, wherein the selection of signal properties is based on a multipath analyzer.

8. The apparatus of claim 7, wherein the multipath analyzer includes a scanning receiver.

9. The apparatus of claim 8 wherein the scanning receiver includes a scanning channel and a tracking channel.

10. The apparatus of claim 7, wherein the multipath analyzer comprises a plurality of correlators.

11. The apparatus of claim 1, wherein the selection of the signal properties of the plurality of pulses depends at least in part on multipath information provided to the transmit-rake apparatus by an external source.

12. The apparatus of claim 1, wherein the selection of the signal properties of the plurality of pulses depends at least in part on signal-quality information provided to the transmit-rake apparatus by an external source.

13. The apparatus of claim 12, wherein the signal-quality information comprises signal-to-noise-ratio or bit-error rate.

14. The apparatus of claim 12, wherein the signal properties of the plurality of pulses are iteratively refined based at least in part on said signal-quality information provided to the transmit-rake apparatus by the external source.

15. The apparatus of claim 1, wherein the ultra-wideband transmit-rake apparatus further comprises:

at least one precision-timing generator, configured to provide at least one timing signal to the at least one pulse generator; and

a controller, configured to provide control signals to the at least one precision-timing generator and the at least one pulse generator.

16. The apparatus of claim 1, wherein the ultra-wideband transmit-rake apparatus further comprises:

at least one delay generator, configured to provide at least one timing signal to the at least one pulse generator;

a precision-timing generator, configured to provide at least one timing signal to the at least one delay generator; and

a controller, configured to provide control signals to the at least one delay generator and the at least one pulse generator.

17. A method of improving signal-to-noise ratio in a communication system, said method comprising:

providing at least one pulse generator in a transmitter, the at least one pulse generator configured to provide a plurality of pulses having individual signal properties selected so as to improve the signal-to-noise ratio at a receiver;

generating the plurality of pulses using the at least one pulse generator; and

providing the plurality of pulses to the receiver.

18. The method of claim 17, wherein the signal properties include pulse timing.

19. The method of claim 17 wherein the signal properties include pulse amplitude.

20. The method of claim 17 wherein the signal properties include pulse polarity.

21. The method of claim 17 wherein the signal properties include pulse shape.

22. The method of claim 17, wherein the pulse generator selects the polarity of each pulse in the plurality of pulses.

23. The method of claim 17, wherein the selection of signal properties is based on a multipath analyzer.

24. The method of claim 23, wherein the multipath analyzer includes a scanning receiver for producing a scan output.

25. The method of claim 24, wherein the scanning receiver includes a scanning channel and a tracking channel.

26. The method of claim 24, wherein the timing of each pulse in said plurality of pulses is based on the timing of the peak amplitudes in said scan output.

27. The method of claim 24, further including the step of correlating the scan output with a signal model to determine a time position for at least one pulse in said plurality of pulses.

28. The method of claim 27, further including the step of subtracting a signal based on the signal model from the scan output to produce a remaining scan output and correlating the remaining scan output with the signal model to produce a subsequent pulse time position.

29. The method of claim 23, in which the multipath analyzer includes a plurality of correlators.

30. The method of claim 17, further including the step of receiving multipath information from an external source, and selecting the signal properties of the plurality of pulses at least in part based on the multipath information.

31. The method of claim 17, further including the step of receiving signal-quality information from an external source, and selecting the signal properties of the plurality of pulses at least in part based on the signal-quality information.

32. The method of claim 31, in which receiving signal-quality information from an external source includes receiving signal-to-noise-ratio or bit-error rate information.

33. The method of claim 17, wherein the pulses are grouped and the pulse properties are varied from group to group.

34. The method of claim 33 wherein the total power for each group is substantially constant.

35. The method of claim 33 wherein the total received signal from each group is substantially constant.

36. The method of claim 33 wherein each pulse has substantially the same amplitude.

37. The method of claim 33 wherein the number of pulses varies from at least one group to at least one other group.

38. The method of claim 17, further including the steps of:

providing at least one precision-timing generator, configured to provide at least one timing signal to the at least one pulse generator; and

providing a controller, configured to provide control signals to the at least one precision-timing generator and the at least one pulse generator.

39. The method of claim 17, further including the steps of:

providing at least one delay generator, configured to provide at least one timing signal to the pulse generator;

providing a precision-timing generator, configured to provide at least one timing signal to the at least one delay generator; and

providing a controller, configured to provide control signals to the at least one delay generator and the at least one pulse generator.

40. A method for increasing the signal to noise performance of an ultra wideband communications link;

said link comprising multiple paths;

said method comprising the steps of;

characterizing the multiple paths of said communications link to identify a plurality of path time delays associated with said multiple paths;

providing a plurality of pulses with relative pulse time delays based on said plurality of path time delays wherein said pulse time delays are arranged in reverse order from said path time delays.