Ultra wide bandwidth spread-spectrum communications system

• US 6,700,939 B1
• Filed: 12/11/1998
• Issued: 03/02/2004
• Est. Priority Date: 12/12/1997
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: XtremeSpectrum, Inc. (Motorola Solutions, Inc.)
• Inventors: McCorkle, John W., Rofheart, Martin
• Primary Examiner(s): Liu, Shuwang
• Application Number:
  US09/209,460
• Time in Patent Office: 1,908 Days
• Field of Search: 375/130, 375/131, 375/140, 375/146, 375/147, 375/149, 375/295, 370/213, 370/324
• US Class Current: 375/295
• CPC Class Codes: H04B 1/71632 Signal aspects H04B1/7172 and H04B1/7176 take precedence
• CPC Class Codes: H04B 1/7172 Pulse shape in general H04L25/03834
• CPC Class Codes: H04B 1/7174 Pulse generation in general H04L25/03834
• CPC Class Codes: H04B 1/7176 Data mapping, e.g. modulation
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04B 1/719 Interference-related aspects
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04L 27/0004 using wavelets

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.

Claims

1. A data communications method, comprising:

processing high-speed digital data for communication to produce processed data;

generating short impulse wavelets;

constructing a digitally modulated ultra wideband signal from the short impulse wavelets in response to bits of the processed data, wherein the digitally modulated ultra wideband signal comprises a series of the short impulse wavelets, and the value of each bit of the processed data is digitally modulated onto the shape of at least one of the short impulse wavelets of the series, to produce a series of digitally shape modulated impulse wavelets; and

transmitting the digitally modulated ultra wideband signal, including the series of digitally shape modulated impulse wavelets.

2. The method of claim 1, wherein each short impulse wavelet of the series has a duration of between 100 and 1000 picoseconds.

3. The method of claim 1, wherein the step of processing comprises:

receiving high-speed digital data as input data;

encoding the input data for forward error correction (FEC); and

differentially encoding the FEC encoded data.

4. The method of claim 3, wherein the step of processing further comprises:

repetitively generating a codeword to produce a digital code signal; and

digitally modulating the digital code signal with bits of data from the differentially encoding step, to generate the processed data.

5. The method of claim 1, wherein the value of each bit of the processed data is biphase modulated onto the shape of said at least one of the short impulse wavelets of the series.

6. The method of claim 1, wherein:

the step of generating comprises generating first short impulse wavelets of a first predetermined shape, and generating second short impulse wavelets having a second predetermined shape; and

the step of constructing comprising selecting between one or more of the first short impulse wavelets and one or more of the second short impulse wavelets, in response to the value of each bit of the processed data.

7. The method as in claim 6, wherein the second predetermined shape is an inverse of the first predetermined shape.

8. The method as in claim 1, wherein the step of processing comprises:

repetitively generating a codeword to produce a digital code signal; and

digitally modulating the digital code signal in accord with bits obtained from the processed high-speed data, to produce the processed data.

9. The method as in claim 8, wherein the step of digitally modulating the digital code signal comprises modulating each instance of the codeword in the digital codeword with one of the bits obtained from the processed data.

10. The method as in claim 1, wherein the step of transmitting comprises:

analog modulating each impulse wavelet in the series of digitally shape modulated impulse wavelets in accord with a code; and

transmitting the analog modulated signal.

11. The method as in claim 1, wherein responsive to each respective modulated short impulse wavelet of the series, the step of transmitting comprises:

generating a plurality of time offset replicas of the respective impulse wavelet;

combining the modulated time offset replicas, in accord with a code, to form coded a group of impulse wavelets derived from the respective impulse wavelet; and

transmitting groups of impulse wavelets derived from the respective impulse wavelets in series.

12. The method as in claim 1, wherein the step of transmitting comprises transmitting a carrierless baseband signal containing the digitally modulated ultra wideband signal.

13. The method as in claim 1, further comprising:

receiving the digitally modulated ultra wideband signal; and

demodulating the series of digitally shape modulated impulse wavelets to recover the high-speed digital data.

14. A data communications method, comprising:

processing high-speed digital data for communication;

repetitively generating a codeword to produce a digital code signal; and

digitally modulating the digital code signal with bits of data obtained from the high-speed digital data, to produce a modulated code signal;

generating short impulse wavelets;

constructing a digitally modulated ultra wideband signal from the short impulse wavelets in response to bits of the modulated code signal, wherein the digitally modulated ultra wideband signal comprises a series of the short impulse wavelets, and the value of each bit of the modulated code signal is digitally modulated onto the shape of at least one of the short impulse wavelets of the series;

responsive to each respective modulated short impulse wavelet of the series, the step of transmitting comprises;

(a) generating a plurality of time offset replicas of the respective impulse wavelet, and

(b) combining the modulated time offset replicas, in accord with a code, to form a coded group of impulse wavelets derived from the respective impulse wavelet; and

transmitting groups of impulse wavelets derived from the respective impulse wavelets in series.

15. The method of claim 14, wherein the step of processing comprises:

receiving high-speed digital data as input data;

encoding the input data for forward error correction (FEC); and

differentially encoding the FEC encoded data.

16. The method of claim 14, wherein the value of each bit of the modulated code signal is biphase modulated onto the shape of said at least one of the short impulse wavelets of the series.

17. The method of claim 16, wherein:

the step of generating the impulse wavelets comprises;

generating first short impulse wavelets of a first predetermined shape, and generating second short impulse wavelets having a second predetermined shape; and

the step of constructing comprises selecting between one or more of the first short impulse wavelets and one or more of the second short impulse wavelets, in response to the value of each bit of the modulated code signal.

18. The method as in claim 17, wherein the second predetermined shape is an inverse of the first predetermined shape.

19. A data transmitter, comprising:

at least one encoder for processing high-speed digital data to produce processed data;

at least one wavelet generator for generating short impulse wavelets;

means for constructing a digitally modulated ultra wideband signal from the short impulse wavelets in response to bits of the processed data from the at least one encoder, wherein the digitally modulated ultra wideband signal comprises a series of the short impulse wavelets, and the value of each of said bits is digitally modulated onto the shape of at least one of the short impulse wavelets of the series, to produce a series of digitally shape modulated impulse wavelets; and

an output for transmitting the digitally modulated ultra wideband signal, including the series of digitally shape modulated impulse wavelets.

20. The data transmitter as in claim 19, wherein the at least one encoder comprises:

a forward error correction (FEC) encoder, for FEC encoding of the high-speed data; and

a differential encoder coupled to the FEC encoder for differentially encoding the FEC encoded data.

21. The data transmitter as in claim 20, wherein the at least one encoder further comprises:

a chip code generator for repetitively outputting a codeword, to form a cyclical chip code sequence; and

a code modulator responsive to an output of the differential encoder and an output of the chip code generator, for digitally modulating the chip code sequence with bits of differentially encoded data, to form the processed data.

22. The data transmitter as in claim 21, further comprising:

a code modulator coupled between the output and the means for constructing,

wherein the code modulator generates a plurality of time offset replicas of each respective modulated short impulse wavelet of the series, and modulates and combines the time offset replicas of each respective impulse wavelet in accord with a code, to form coded groups of impulse wavelets for the ultra wideband signal transmitted from the output.

23. The data transmitter as in claim 19, further comprising:

a code modulator coupled between the output and the means for constructing,

wherein the code modulator generates a plurality of time offset replicas of each respective modulated short impulse wavelet of the series, and modulates and combines the time offset replicas of each respective impulse wavelet in accord with a code, to form coded groups of impulse wavelets for the transmission.

24. The data transmitter of claim 19, further comprising:

a power amplifier, coupled to the output, for amplifying the digitally modulated ultra wideband signal comprising the series of digitally shape modulated impulse wavelets; and

an antenna coupled to an output of the amplifier for transmitting the digitally modulated ultra wideband signal comprising the series of digitally shape modulated impulse wavelets over a wireless link.

25. The data transmitter of claim 19, wherein the at least one wavelet generator is adapted to generate short impulse wavelets of duration between 100 and 1000 picoseconds.

26. The data transmitter of claim 19, wherein the at least one wavelet generator comprises:

a first wavelet generator for generating first short impulse wavelets having a first predetermined shape, and

a second wavelet generator for generating second short impulse wavelets having a second predetermined shape;

wherein the means for constructing comprises a selector for selecting between one or more of the first short impulse wavelets and one or more of the second short impulse wavelets, in response to the value of each bit of the processed data from the at least one encoder.

27. The data transmitter of claim 26, wherein the second wavelet generator generates second short impulse wavelets having a shape corresponding to an inverse of the first predetermined shape.

28. A data transmitter, comprising:

at least one encoder for processing high-speed digital data for transmission;

at least one wavelet generator for generating first short impulse wavelets having a first predetermined shape, and for generating second short impulse wavelets having a second predetermined shape;

a selector responsive to bits of the processed high-speed data for selecting between one or more of the first short impulse wavelets and one or more of the second short impulse wavelets, in response to the value of each bit of the processed high-speed data, to form a digitally modulated ultra wideband signal comprising a series of the short impulse wavelets having the first and second shapes; and

an output for transmitting the digitally modulated ultra wideband signal to a remote device.

29. A data transmitter, comprising:

at least one encoder for processing high-speed digital data, the at least one encoder comprising;

a) a chip code generator for repetitively outputting a codeword, to form a cyclical chip code sequence, and

b) a code modulator responsive to an output of the differential encoder and an output of the chip code generator, for digitally modulating the chip code sequence with bits of differentially encoded data, to form processed high-speed data;

at least one wavelet generator, for generating first short impulse wavelets having a first predetermined shape, and for generating second short impulse wavelets having a second predetermined shape;

a selector responsive to bits of the processed high-speed data for selecting between one or more of the first short impulse wavelets and one or more of the second short impulse wavelets, in response to the value of each bit of the processed high-speed data, to form a digitally modulated ultra wideband signal comprising a series of the short impulse wavelets having the first and second shapes;

a code modulator coupled between the output of the chip code generator and the selector, wherein the code modulator generates a plurality of time offset replicas of each respective short impulse wavelet of the series, and modulates and combines the time offset replicas of each respective impulse wavelet in accord with a code, to form coded groups of impulse wavelets for transmission to a remote device.

30. A high-speed digital data communications system, comprising:

at least one encoder for processing first high-speed digital data for transmission;

at least one wavelet generator for generating short impulse wavelets;

means for constructing a digitally modulated ultra wideband signal from the short impulse wavelets in response to bits of the processed first high-speed digital data from the at least one encoder, wherein the digitally modulated ultra wideband signal comprises a series of the short impulse wavelets, and the value of each of said bits is digitally modulated onto the shape of at least one of the short impulse wavelets of the series, to produce a series of digitally shape modulated impulse wavelets;

an output for transmitting the digitally modulated ultra wideband signal, including the series of digitally shape modulated impulse wavelets to at least one remote device;

a receiver, for receiving a digitally modulated ultra wideband signal from at least one remote device; and

a demodulator coupled to the receiver for demodulating a series of digitally shape modulated impulse wavelets in the digitally modulated ultra wideband signal received from at least one remote device, to recover second high-speed digital data.