Communications channel characterization device and associated methods

• US 7,085,539 B2
• Filed: 01/30/2004
• Issued: 08/01/2006
• Est. Priority Date: 01/30/2004
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Furman, William Nelson
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US10/768,247
• Publication Number:
  US 20050170780A1
• Time in Patent Office: 914 Days
• Field of Search: 455/67.11, 455/67.13, 455/67.14, 455/67.16, 455/424, 455/226.2, 375/224, 375226-227
• US Class Current: 455/67.13
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0224 using sounding signals

Abstract

The system and method characterize a communications channel with respect to signal-to-noise ratio (SNR), time dispersion or multi-path, and frequency dispersion or Doppler spread. A probe signal demodulator receives a probe signal transmitted on a wireless communication channel and generates a demodulated probe signal, and a probe signal re-modulator generates a replica probe signal. A delay unit generates a delayed probe signal, and an adaptive canceller receives the delayed probe signal and the replica probe signal, and generates a residual noise signal and a channel characterization signal. A channel characterization block receives the channel characterization signal and the residual noise signal to generate channel measurements of the wireless communication channel.

Claims

1. A communication channel measurement unit comprising:

an input to receive a probe signal transmitted on a wireless communication channel;

a probe signal demodulator connected to the input;

a probe signal re-modulator connected downstream of the probe signal demodulator to generate a replica probe signal;

a delay unit connected to the input to generate a delayed probe signal; and

an adaptive canceller to generate a residual noise signal and a channel characterization signal based upon the delayed probe signal and the replica probe signal.

2. A communication channel characterization unit according to claim 1 further comprising:

a first power measurement unit connected to the input to generate a signal-and-noise power measurement signal;

a second power measurement unit to receive the residual noise signal and generate a residual noise power measurement signal; and

a signal-to-noise determination unit to receive the signal-and-noise power measurement signal and the residual noise power measurement signal, and to determine a signal-to-noise ratio of the wireless communication channel.

3. A communication channel characterization unit according to claim 1 further comprising

a multipath estimation unit to receive the channel characterization signal and estimate the number of multipath propagation modes and a total time spread of the wireless communication channel.

4. A communication channel characterization unit according to claim 1 further comprising a Doppler estimation unit to receive the channel characterization signal and estimate frequency dispersion on the wireless communication channel.

5. A communication channel characterization unit according to claim 1 further comprising a channel characterization block to receive the channel characterization signal and the residual noise signal to generate channel measurements of the wireless communication channel.

6. A communication channel characterization unit according to claim 5 wherein the channel characterization block comprises:

a first power measurement unit connected to the input to generate a signal-and-noise power measurement signal;

a second power measurement unit to receive the residual noise signal and generate a residual noise power measurement signal;

a signal-to-noise determination unit to receive the signal-and-noise power measurement signal and the residual noise power measurement signal, and to determine a signal-to-noise ratio of the wireless communication channel;

a multipath estimation unit to receive the channel characterization signal and estimate the number of multipath propagation modes and a total time spread of the wireless communication channel; and

a Doppler estimation unit to receive the channel characterization signal and estimate frequency dispersion on the wireless communication channel.

7. A communication channel characterization unit according to claim 1 wherein the adaptive canceller comprises:

a linear filter having adjustable taps; and

a subtracter associated with the linear filter.

8. A communication channel characterization unit according to claim 1 wherein probe signal is received on a wireless communication channel in a High Frequency (HF) band between 3 MHz to 30 MHz.

9. A communication channel measurement unit comprising:

a probe signal demodulator to receive a probe signal transmitted on a wireless communication channel and generate a demodulated probe signal;

a probe signal re-modulator to receive the demodulated probe signal and generate a replica probe signal;

a delay unit to receive the probe signal transmitted on the wireless communication channel and generate a delayed probe signal;

an adaptive canceller to generate a residual noise signal and a channel characterization signal based upon the delayed probe signal and the replica probe signal; and

a channel characterization block to receive the channel characterization signal and the residual noise signal to generate channel measurements of the wireless communication channel.

10. A communication channel characterization unit according to claim 9 wherein the channel characterization block comprises:

a first power measurement unit to receive the probe signal transmitted on the wireless communication channel and to generate a signal-and-noise power measurement signal;

a second power measurement unit to receive the residual noise signal and generate a residual noise power measurement signal; and

a signal-to-noise determination unit to receive the signal-and-noise power measurement signal and the residual noise power measurement signal, and to determine a signal-to-noise ratio of the wireless communication channel.

11. A communication channel characterization unit according to claim 9 wherein the channel characterization block comprises a multipath estimation unit to receive the channel characterization signal and estimate the number of multipath propagation modes and a total time spread of the wireless communication channel.

12. A communication channel characterization unit according to claim 9 wherein the channel characterization block comprises a Doppler estimation unit to receive the channel characterization signal and estimate frequency dispersion on the wireless communication channel.

13. A communication channel characterization unit according to claim 9 wherein the channel characterization block further comprises:

a first power measurement unit connected to receive the probe signal transmitted on the wireless communication channel and to generate a signal-and-noise power measurement signal;

a second power measurement unit to receive the residual noise signal and generate a residual noise power measurement signal;

a signal-to-noise determination unit to receive the signal-and-noise power measurement signal and the residual noise power measurement signal, and to determine a signal-to-noise ratio of the wireless communication channel;

a multipath estimation unit to receive the channel characterization signal and estimate the number of multipath propagation modes and a total time spread of the wireless communication channel; and

a Doppler estimation unit to receive the channel characterization signal and estimate frequency dispersion on the wireless communication channel.

14. A communication channel characterization unit according to claim 9 wherein the adaptive canceller comprises:

a linear filter having adjustable taps; and

a subtracter associated with the linear filter.

15. A communication channel characterization unit according to claim 9 wherein probe signal is received on a wireless communication channel in a High Frequency (HF) band between 3 MHz to 30 MHz.

16. A communication channel measurement unit comprising:

a probe signal demodulator to receive a probe signal transmitted on a wireless communication channel and generate a demodulated probe signal;

a probe signal re-modulator to receive the demodulated probe signal and generate a replica probe signal;

a delay unit to receive the probe signal transmitted on the wireless communication channel and generate a delayed probe signal;

an adaptive canceller to generate a channel characterization signal based upon the delayed probe signal and the replica probe signal; and

a channel characterization block to generate channel measurements of the wireless communication channel based upon the channel characterization signal.

17. A communication channel characterization unit according to claim 16 wherein the channel characterization block comprises a multipath estimation unit to receive the channel characterization signal and estimate the number of multipath propagation modes and a total time spread of the wireless communication channel.

18. A communication channel characterization unit according to claim 16 wherein the channel characterization block comprises a Doppler estimation unit to receive the channel characterization signal and estimate frequency dispersion on the wireless communication channel.

19. A communication channel measurement unit comprising:

a probe signal demodulator to receive a probe signal transmitted on a wireless communication channel and generate a demodulated probe signal;

a probe signal re-modulator to receive the demodulated probe signal and generate a replica probe signal;

a delay unit to receive the probe signal transmitted on the wireless communication channel and generate a delayed probe signal;

an adaptive canceller to generate a residual noise signal based upon the delayed probe signal and the replica probe signal; and

a channel characterization block to generate channel measurements of the wireless communication channel based upon the residual noise signal.

20. A communication channel characterization unit according to claim 19 wherein the channel characterization block comprises:

a first power measurement unit to receive the probe signal transmitted on the wireless communication channel and to generate a signal-and-noise power measurement signal;

a second power measurement unit to receive the residual noise signal and generate a residual noise power measurement signal; and

a signal-to-noise determination unit to receive the signal-and-noise power measurement signal and the residual noise power measurement signal, and to determine a signal-to-noise ratio of the wireless communication channel.

21. A method of characterizing a communication channel comprising:

receiving and demodulating a probe signal transmitted on a wireless communication channel to generate a demodulated probe signal;

re-modulating the demodulated probe signal to generate a replica probe signal;

generating a residual noise signal and a channel characterization signal based upon a delayed probe signal and the replica probe signal; and

generating channel measurements of the wireless communication channel based upon the channel characterization signal and the residual noise signal.

22. A method according to claim 21 wherein generating channel measurements comprises:

measuring a signal-and-noise power of the probe signal transmitted on the wireless communication channel;

measuring a residual noise power of the residual noise signal; and

determining a signal-to-noise ratio of the wireless communication channel based upon the measured signal-and-noise power and the measured residual noise power.

23. A method according to claim 21 wherein generating channel measurements comprises estimating the number of multipath propagation modes and a total time spread of the wireless communication channel based upon the channel characterization signal.

24. A method according to claim 21 wherein generating channel measurements comprises estimating frequency dispersion on the wireless communication channel based upon the channel characterization signal.

25. A method according to claim 21 wherein generating channel measurements comprises:

measuring a signal-and-noise power of the probe signal transmitted on the wireless communication channel;

measuring a residual noise power of the residual noise signal;

determining a signal-to-noise ratio of the wireless communication channel based upon the measured signal-and-noise power and the measured residual noise power;

estimating the number of multipath propagation modes and a total time spread of the wireless communication channel based upon the channel characterization signal; and

estimating frequency dispersion on the wireless communication channel based upon the channel characterization signal.