Communications channel characterization device and associated methods
View Patent ↗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.
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.