Ultra wide bandwidth spread-spectrum communications system

• US 7,408,973 B2
• Filed: 06/24/2005
• Issued: 08/05/2008
• Est. Priority Date: 12/12/1997
• Status: Expired due to Fees

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McCorkle, John W., Rofheart, Martin
• Primary Examiner(s): Ghayour, Mohammad H.
• Assistant Examiner(s): Torres, Juan A.
• Application Number:
  US11/165,519
• Publication Number:
  US 20050259720A1
• Time in Patent Office: 1,138 Days
• Field of Search: 375/130
• US Class Current: 375/130
• 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. 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 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 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:

receiving a stream of digital data that are mapped such that a first data value corresponds to a positive value and a second data value corresponds to a negative data value;

repetitively generating a codeword to produce a digital code signal;

modulating the codeword digital code signal by either the positive value or the negative value in accord with the digital data, to generate a modulated code signal;

generating a modulated ultrawideband impulse signal by modulating the modulated code signal with a pulse shape; and

outputting the modulated ultrawideband impulse signal.

2. The method of claim 1, wherein in the operation of generating a modulated ultrawideband impulse signal, each bit of the modulated code signal is modulated individually onto the pulse shape.

3. The method of claim 2, wherein:

the generating of the modulated ultrawideband impulse signal comprises;

generating a first pulse having a first predetermined shape,

generating second pulse having a second predetermined shape that is an inverse of the first pulse shape; and

selecting between the first pulse and the second pulse in response to a value of each bit of the modulated code signal.

4. The method of claim 1, wherein the pulse shape corresponds to a pulse wavelet having a duration between 100 and 1000 picoseconds.

5. The method of claim 1, wherein the codeword comprises a Barker code.

6. The method of claim 1, further comprising processing the stream of digital data prior to the modulating of the codeword digital code signal in accord with the digital data.

7. The method of claim 6, wherein the processing of the stream of digital data comprises one or more of:

forward error correction (FEC) encoding, differential encoding, and modulating a separate code signal comprising a repeating codeword.

8. The method of claim 6, wherein the outputting of the modulated ultrawideband impulse signal comprises transmitting the modulated ultrawideband impulse signal as a carrierless baseband signal.

9. The method of claim 6, further comprising:

receiving the modulated ultrawideband impulse signal;

compressing code modulated groups of pulses in the received modulated ultrawideband impulse signal, to form a received modulated sequence of pulses; and

demodulating the received modulated sequence of pulses, to recover the stream of digital data.