Receiver for use in an ultra-wideband communication system
In an ultra-wideband (“UWB”) receiver, a received UWB signal is periodically digitized as a series of ternary samples. The samples are continuously correlated with a predetermined preamble sequence to develop a correlation value. When the value exceeds a predetermined threshold, indicating that the preamble sequence is being received, estimates of the channel impulse response (“CIR”) are developed. When a start-of-frame delimiter (“SFD”) is detected, the best CIR estimate is provided to a channel matched filter (“CMF”) substantially to filter channel-injected noise.
1. An estimator for use in an ultra-wideband (UWB) communication system in which multi-symbol packets are transmitted via a transmission channel, each transmitted packet comprising a synchronization header (SHR), the estimator comprising:
an analog-to-digital converter (ADC) adapted to:
receive a conditioned form of a received packet;
periodically sample said packet at a selected over-sample rate; and
provide corresponding samples;
a digital correlator adapted to:
receive selected samples of each symbol of the SHR;
periodically select at a selected up-sample rate a set of the selected samples; and
develop from each of said sample sets a partial finite impulse response (FIR) of said channel to each symbol;
a digital accumulator adapted to:
receive each partial FIR developed by the correlator;
accumulate the partial FIRs for at least a selected subset of all symbols comprising the SHR; and
develop from the accumulated partial FIRs for said selected subset of said symbols a best estimate of a channel impulse response (CIR) comprising an impulse response of said channel.
2. The estimator of claim 1 wherein each of said samples comprises at least two distinct values.
3. The estimator of claim 1 wherein each of said samples comprises a single bit having two distinct values.
4. The estimator of claim 1 wherein each of said samples comprises a single trit having three distinct values.
5. The estimator of claim 1 wherein each of said samples comprises three distinct values.
6. The estimator of claim 1 further comprising:
a preamble detector adapted to:
develop a first CIR estimate over a predetermined number of the most-recently-received preamble symbols;
correlate the first CIR estimate with a stored second CIR estimate; and
replace the second CIR estimate with the first CIR estimate until the first CIR estimate sufficiently resembles the stored second CIR estimate.
7. A receiver for use in an ultra-wideband (UWB) communication system in which multi-symbol packets are transmitted via a transmission channel, each transmitted packet comprising a multi-symbol synchronization header (SHR) and a multi-symbol data payload, the SHR comprising a preamble and a start-of-frame delimiter (SFD), the receiver comprising:
an analog UWB front-end adapted to receive a transmitted packet and to provide a conditioned form of the received packet;
an analog-to-digital converter (ADC) adapted to:
receive the conditioned packet;
periodically sample said packet at a selected over-sample rate; and
provide corresponding samples;
a digital polyphase correlator, each phase of which is adapted to:
receive selected samples of each symbol of the SHR;
periodically select at a selected up-sample rate a set of the selected samples; and
develop from each of said sample sets a partial finite impulse response (FIR) of said channel to each symbol;
a digital polyphase accumulator, each phase of which is adapted to:
receive each partial FIR developed by a selected phase of the correlator; and
accumulate the partial FIRs for at least a selected subset of all symbols comprising the SHR; and
develop from the accumulated partial FIRs for said selected subset of said symbols a best estimate of a channel impulse response (CIR) of said channel.
8. The receiver of claim 7 wherein each of said samples comprises at least two distinct values.
9. The receiver of claim 7 wherein each of said samples comprises a single bit having two distinct values.
10. The receiver of claim 7 wherein each of said samples comprises a single trit having three distinct values.
11. The receiver of claim 7 wherein each of said samples comprises three distinct values.
12. The receiver of claim 7 further comprising:
a preamble detector adapted to:
develop a first CIR estimate over a predetermined number of the most-recently-received preamble symbols;
correlate the first CIR estimate with a stored second CIR estimate; and
replace the second CIR estimate with the first CIR estimate until the first CIR estimate sufficiently resembles the stored second CIR estimate.
13. The receiver of claim 7 further comprising:
a digital polyphase channel matched filter (CMF), each phase of which is adapted to:
receive a selected portion of said best CIR estimate;
receive selected samples of each symbol of said data payload; and
filter said received samples with the time reversed conjugate of said received selected portion of said best estimate of the CIR.
14. The receiver of claim 13 wherein the CMF is further adapted to provide a filtered data payload by selectively combining the filtered samples.
15. A receiver for use in an ultra-wideband (UWB) communication system in which multi-symbol packets are transmitted via a transmission channel, each transmitted packet comprising a multi-symbol synchronization header (SHR) and a multi-symbol data payload, the SHR comprising a preamble and a start-of-frame delimiter (SFD), the receiver comprising:
an analog UWB front-end adapted to receive a transmitted packet and to provide a conditioned form of the received packet;
an analog-to-digital converter (ADC) adapted to:
receive the conditioned packet;
periodically sample said packet at a selected over-sample rate; and
provide corresponding samples;
a digital correlator adapted to:
receive selected samples of each symbol of the SHR;
periodically select at a selected up-sample rate a set of the selected samples; and
develop from each of said sample sets a partial finite impulse response (FIR) to each symbol;
a digital accumulator adapted to:
receive each partial FIR developed by the correlator; and
accumulate the partial FIRs for all symbols comprising the SHR; and
a digital windowing block adapted to:
receive the accumulated partial FIRs for selected subsets of said symbols; and
develop from the accumulated partial FIRs for all of said subsets a best estimate of a channel impulse response (CIR) of said channel; and
a digital channel matched filter (CMF) adapted to:
receive a selected portion of said best CIR estimate;
receive selected samples of each symbol of said data payload;
filter said received samples with the time reversed conjugate of said received selected portion of said best estimate of the CIR; and
provide, for each symbol of said data payload, a filtered symbol by selectively combining the filtered samples of said symbol.
16. The receiver of claim 15 wherein each of said samples comprises at least two distinct values.
17. The receiver of claim 15 wherein each of said samples comprises a single bit having two distinct values.
18. The receiver of claim 15 wherein each of said samples comprises a single trit having three distinct values.
19. The receiver of claim 15 wherein each of said samples comprises three distinct values.
20. The receiver of claim 15 further comprising:
a preamble detector adapted to:
develop a first CIR estimate over a predetermined number of the most-recently-received preamble symbols;
correlate the first CIR estimate with a stored second CIR estimate; and
replace the second CIR estimate with the first CIR estimate until the first CIR estimate sufficiently resembles the stored second CIR estimate.