Ultra wide bandwidth spread-spectrum communications system
First Claim
1. A data communications method, comprising:
- producing a bit stream in response to high-speed digital data for communication;
in response to the bit stream, generating a sequence of short impulse wavelets, wherein the sequence of short impulse wavelets is modulated in accord with bits of the bit stream;
responsive to each respective short impulse wavelet of the modulated sequence, (a) generating a plurality of time offset replicas of the respective short impulse wavelet, and (b) combining the time offset replicas, in accord with a code, to form a coded group of impulse wavelets derived from the respective short impulse wavelet; and
outputting the coded groups of impulse wavelets in sequence, as a modulated ultrawideband impulse signal.
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Abstract
An ultra wide bandwidth, high speed, spread spectrum communications system uses short wavelets of electromagnetic energy to transmit information through objects such as walls or earth. The communication system uses baseband codes formed from time shifted and inverted wavelets to encode data on a RF signal. Typical wavelet pulse durations are on the order of 100 to 1000 picoseconds with a bandwidth of approximately 8 GHz to 1 GHz, respectively. The combination of short duration wavelets and encoding techniques are used to spread the signal energy over an ultra wide frequency band such that the energy is not concentrated in any particular narrow band (e.g. VHF: 30-300 MHz or UHF: 300-1000 MHz) and is not detected by conventional narrow band receivers so it does not interfere with those communication systems. The use of pulse codes composed of time shifted and inverted wavelets gives the system according to the present invention has a spatial resolution on the order of 1 foot which is sufficient to minimize the negative effects of multipath interference and permit time domain rake processing.
280 Citations
46 Claims
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1. A data communications method, comprising:
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producing a bit stream in response to high-speed digital data for communication;
in response to the bit stream, generating a sequence of short impulse wavelets, wherein the sequence of short impulse wavelets is modulated in accord with bits of the bit stream;
responsive to each respective short impulse wavelet of the modulated sequence, (a) generating a plurality of time offset replicas of the respective short impulse wavelet, and (b) combining the time offset replicas, in accord with a code, to form a coded group of impulse wavelets derived from the respective short impulse wavelet; and
outputting the coded groups of impulse wavelets in sequence, as a modulated ultrawideband impulse signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A data communications method, comprising:
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receiving an input of high-speed digital data for communication;
processing the high-speed digital data;
generating a sequence of short impulse wavelets;
modulating the sequence of short impulse wavelets in response to the processed high speed data so as to produce a modulated sequence of short impulse wavelets;
responsive to each respective short impulse wavelet of the modulated sequence, (a) generating a plurality of time offset replicas of the respective short impulse wavelet; and
(b) adding and subtracting the time offset replicas, in accord with a predetermined binary code, to form a code modulated group of impulse wavelets derived from the respective short impulse wavelet;
transmitting the code modulated groups of impulse wavelet in sequence, as a modulated ultrawideband impulse signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An ultrawideband impulse transmitter, for transmitting high-speed digital data for communication, comprising:
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an input for receiving the high-speed digital data for communication;
a digital impulse modulator responsive to a stream of bits obtained in response to the high-speed digital data for generating a modulated sequence of short impulse wavelets, the sequence being modulated in accord with the stream of bits;
a code modulator, concatenated with the digital impulse modulator, for converting each respective short impulse wavelet in the modulated sequence into a respective group of short impulse wavelets and thereby forming a modulated ultrawideband impulse signal for transmission, the respective group of short impulse wavelets being modulated in accord with a code. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of receiving high-speed data via ultrawideband impulse communication, comprising:
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receiving a modulated ultrawideband impulse signal transmitted from a remote location, wherein the received modulated ultrawideband impulse signal comprises group of code modulated short impulse wavelets;
compressing the code modulated groups of short impulse wavelets in the received modulated ultrawideband impulse signal to recover a sequence of impulse wavelets modulated with bits obtained from the high-speed data from the received modulated ultrawideband impulse signal;
generating a local ultrawideband impulse signal comprising a local sequence of short impulse wavelets;
locking timing of the local modulated ultrawideband impulse signal to the recovered sequence of impulse wavelets; and
correlating the locked local modulated ultrawidebend impulse signal to the recovered sequence of impulse wavelets to detect the bits obtained from the high-speed data. - View Dependent Claims (36, 37)
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38. A method of receiving high-speed data via ultrawideband impulse communication, comprising:
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receiving a modulated ultrawideband impulse signal transmitted from a remote location, wherein the received modulated ultrawidebend impulse signal comprises groups of code modulated short impulse wavelets;
generating a local sequence of short impulse wavelets;
for each respective short impulse wavelet contained in the local sequence, generating a plurality of time offset replicas of the respective short impulse wavelet modulated in accord with a code, and thereby forming a local ultrawideband impulse signal;
locking timing of the local modulated ultrawideband impulse signal to the received modulated ultrawideband impulse signal; and
correlating the locked local modulated ultrawideband impulse signal to the received modulated ultrawideband impulse signal to detect bits obtained from the high-speed data. - View Dependent Claims (39, 40)
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41. An ultrawideband impulse receiver, for receiving high-speed digital data, comprising:
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a receiver front end for receiving a modulated ultrawideband impulse signal transmitted from a remote location, wherein the received modulated ultrawideband impulse signal comprise groups of short impulse wavelets modulated in accord with a code;
a matched filter for applying the code to the groups of short impulse wavelets to compress the groups of short impulse wavelets so as to form a sequence of individual short impulse wavelets; and
a correlator for demodulating the sequence of individual short impulse wavelets to recover bits corresponding to the high-speed digital data, wherein the correlator comprises;
means for generating a local ultrawideband impulse signal; and
a delay lock loop for locking timing of the local modulated ultrawideband impulse signal to timing of the received modulated ultrawideband impulse signal, and for using the locked local modulated ultrawideband impulse signal to recover the bits corresponding to the high-speed digital data from the received modulated ultrawideband impulse signal. - View Dependent Claims (42)
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43. An ultrawideband impulse receiver, for receiving high-speed digital data, comprising:
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a receiver front end for receiving a modulated ultrawideband impulse signal transmitted from a remote location, wherein the received modulated ultrawideband impulse signal comprises groups of short impulse wavelets modulated in accord with a code; and
an impulse generator for generating a local sequence of short impulse wavelets;
a code modulator, concatenated with the impulse generator, for converting each respective short impulse wavelet in the local modulated sequence into a respective group of short impulse wavelets and thereby forming a local modulated in accord with the code; and
a delay lock loop for locking timing of the local modulated ultrawideband impulse signal to timing of the received modulated ultrawideband impulse signal, and for using the locked local modulated ultrawideband impulse signal to recover bits corresponding to the high-speed digital data from the received modulated ultrawideband impulse signal. - View Dependent Claims (44, 45)
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46. A data communications method, comprising:
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a step for producing a bit stream in response to high-speed digital data for communication;
a step, responsive to the bit stream, for generating a sequence of short impulse wavelets, wherein the sequence of short impulse wavelets is modulated in accord with bits of the bit stream;
responsive to each respective short impulse wavelet of the modulated sequence, (a) a step for generating a plurality of time offset replicas of the respective short impulse wavelet, and (b) a step for combining the time offset replicas, in accord with a code, to form a coded group of impulse wavelets derived from the respective short impulse wavelet; and
a step for outputting the coded groups of impulse wavelets in sequence, as a modulated ultrawideband impulse signal.
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Specification