RF communication system having a chaotic signal generator and method for generating chaotic signal

Abstract

A radio frequency (RF) communication system having a chaotic signal generator and a method of generating a chaotic signal. The RF communication system includes a chaotic signal generator which generates a chaotic signal having a plurality of frequency components at a predetermined frequency band, a modulator which generates a chaotic carrier by combining the chaotic signal with a data signal which indicates information, and a transmission circuit which includes an antenna to transmit the chaotic carrier made at the modulator. The frequency signal generator comprises an oscillator which converts a DC bias power into a high frequency power, and a resonating unit which generates a wideband signal having a plurality of frequency components by passing a predetermined frequency band of the high frequency power signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 shows a block diagram of a transceiver of a RF communication system using chaotic signal, and graphical representations of signal waves in respective domains of the RF communication system;

FIG. 2A shows, in enlargement, waves of chaotic signals generated from a chaotic signal generator of FIG. 1;

FIG. 2B shows a graphical representation showing the chaotic signal of FIG. 2A based on frequency domain;

FIG. 2C is a graphical representation of an enlarged data signal;

FIG. 2D shows a graphical representation of chaotic carrier by modulating the chaotic signal of FIG. 2A and the data signal of FIG. 2C;

FIG. 2E is a graphical representation of the chaotic carrier of FIG. 2D based on frequency domain;

FIG. 3 is a graphical representation of a frequency bandwidth of a chaotic signal region 1 T and a pulse region 3 T;

FIG. 4 is a block diagram of a chaotic signal generator according to an exemplary embodiment of the present invention;

FIG. 5 is a block diagram of a chaotic signal generator according to an exemplary embodiment of the present invention;

FIG. 6 is a graphical representation of chaotic signal generated from the chaotic signal generator based on the time domain;

FIG. 7 is a graphical representation of the result of measuring power spectrum density of chaotic signal according to an exemplary embodiment of the present invention;

FIG. 8A is a graphical representation of an example of a signal mask defined by the Federal Communications Commission (FCC);

FIG. 8B shows a power spectrum of chaotic signal generated by a chaotic signal generator based on the mask of FIG. 8A;

FIG. 9A is a graphical representation of time domain of chaotic carrier which combines the chaotic signal of FIG. 6 with the data signal; and

FIG. 9B is a power spectrum of chaotic carrier of FIG. 9A.

Claims

1. A radio frequency (RF) communication system comprising: a chaotic signal generator which generates a chaotic signal having a plurality of frequency components at a predetermined frequency band;a modulator which generates a chaotic carrier by combining the chaotic signal with a data signal; anda transmission circuit comprising an antenna to transmit the chaotic carrier generated by the modulator.

2. The RF communication system of claim 1, wherein the chaotic signal generator comprises an oscillator which converts a direct current (DC) bias power into the high frequency power, and a resonating unit which generates a wideband signal having a plurality of frequency components by passing the predetermined frequency band of the high frequency power signal.

3. The RF communication system of claim 2, wherein the resonating unit comprises: a first filter which receives the high frequency power from the oscillator and passes at least a part of a harmonic signal of the high frequency power as a filtered signal; anda second filter which generates the wideband signal having the plurality of frequency components of the predetermined range of frequency band by oscillating the filtered signal, and provides the oscillator with the wideband signal.

4. The RF communication system of claim 3, wherein the oscillator comprises a nonlinear element, and high frequency power of the nonlinear element is determined by:

5. The RF communication system of claim 4, wherein the nonlinear element comprises one of a transistor and a diode.

6. The RF communication system of claim 5, wherein the chaotic signal generator enables oscillation if a phase variance of a signal passing a loop of the nonlinear element, the first filter and the second filter is a multiple of 2π.

7. The RF communication system of claim 6, wherein the chaotic signal generator additionally enables the oscillation if a total gain of the loop is larger than 1.

8. The RF communication system of claim 3, wherein the signal outputted from the first filter is determined by: Tx1′+x1=f(zN)wherein, f(zN) is a function of high frequency output from the oscillator, T is a time constant of the first filter, and x1 is an initial signal outputted from the first filter.

9. The RF communication system of claim 8, wherein the first filter comprises a low pass filter (LPF).

10. The RF communication system of claim 9, wherein the first filter is a primary filter.

11. The RF communication system of claim 1, wherein the second filter comprises at least one band pass filter (BPF).

12. The RF communication system of claim 11, wherein the BPF is a secondary filter.

13. The RF communication system of claim 11, wherein the second filter comprises a plurality of N BPFs and an (N)th output from an (N)th BPF is determined by: zN″+αBNz′N+ωBN2zN=ωBN2zN-1′wherein, zN-1 is an output from an (N−1)th BPF, that is, an input to the (N)th BPF, αBN is an attenuation constant, ωBN is a resonating frequency and zN is an output from the (N)th BPF.

14. The RF communication system of claim 13, wherein the plurality of N BPFs determines a resonating frequency band of the chaotic signal generator.

15. The RF communication system of claim 1, wherein the second filter comprises at least one LPF.

16. The RF communication system of claim 15, wherein the LPF of the second filter is a secondary filter.

17. The RF communication system of claim 16, wherein the second filter further comprises a band pass filter (BPF) and the LPF of the second filter is disposed between the first filter and the BPF.

18. The RF communication system of claim 17, wherein the second filter comprises a plurality of M LPFs and an output from an (M)th LPF of the second filter is determined by: yM″+αLMyM′+ωLM2yM=ωLM2yM-1 wherein, yM-1 is an output from an (M−1)th LPF, that is, an input to the (M)th LPF, αLM is an attenuation constant, ωLM is a resonating frequency, and yM is an output from the (M)th LPF.

19. The RF communication system of claim 18, wherein the plurality of M LPFs and the BPF of the second filter have different delayed phase widths and gains.

20. The RF communication system of claim 19, wherein the BPF is a predetermined number of BPFs so that a phase of a signal passing a loop of the oscillator, the first filter and the second filter corresponds to a multiple of 2π.

21. A radio frequency (RF) communication system comprising: a nonlinear element which converts a direct current (DC) bias power into a high frequency power;a first low pass filter (LPF) which filters the high frequency power into a predetermined frequency band;at least one second LPF which shifts the filtered high frequency power according to a predetermined phase width to generate a shifted signal; andat least one band pass filter (BPF) which has a difference phase width than the at least one second LPF, and filter the shifted signal into a predetermined frequency band.

22. The RF communication system of claim 21, wherein the at least one BPF comprises a first BPF, a second BPF and a third BPF.

23. A radio frequency (RF) communication system comprising: an oscillator which converts a direct current (DC) bias power into a high frequency power; anda resonating unit which generates a wideband signal having a plurality of frequency components by passing a predetermined frequency band of the high frequency power signal.

24. A radio frequency (RF) communication system comprising: a nonlinear element which converts a direct current (DC) bias power into a high frequency power;a first filter which receives the high frequency power from the nonlinear element and passes at least a part of a harmonic signal of the high frequency power; anda second filter comprising at least one low pass filter (LPF) and at least one band pass filter (BPF), which generates a wideband signal having a plurality of frequency components in a predetermined range of frequency band by oscillating a signal from the first filter, and provides the nonlinear element with the wideband signal.

25. A radio frequency (RF) communication system comprising: a nonlinear element which converts a direct current (DC) bias power into a high frequency power;a first filter which receives the high frequency power from the nonlinear element and passes at least a part of a harmonic signal of the high frequency power; andat least one second filter which generates a wideband signal having a plurality of frequency components in a predetermined range of frequency band by oscillating a signal from the first filter, and provide the nonlinear element with the wideband signal.

26. A radio frequency (RF) communication system comprising: a nonlinear element which converts a direct current (DC) bias power into a high frequency power;a first filter which receives the high frequency power from the nonlinear element and passes at least a part of a harmonic signal of the high frequency power; anda second filter comprising one or more LPFs and one or more BPFs which generates a wideband signal having a plurality of frequency components in a predetermined range of frequency band by oscillating a signal from the first filter, and provides the nonlinear element with the wideband signal.

27. A method of generating a chaotic signal in a radio frequency (RF) communication system, the method comprising: converting a direct current (DC) bias power into a high frequency power;generating an initial signal which meets initial conditions for oscillation using the high frequency power; andgenerating a wideband signal having a plurality of frequency components in a predetermined range of frequency band by oscillating the initial signal.

28. The method of claim 27, wherein the high frequency power is generated by:

29. The method of claim 28, wherein the nonlinear element comprises a transistor.

30. The method of claim 27, wherein a loop is generated during the process of converting the DC bias power into the wideband signal and a phase of a signal passing the loop corresponds to a multiple of 2π in order for the oscillating to occur.

31. The method of claim 27, wherein a total gain of the loop is larger than 1 in order for the oscillating to occur.

32. The method of claim 27, wherein the initial signal is determined by: Tx1′+x1=f(zN)wherein, f(zN) is a function of high frequency output from a nonlinear element, T is a time constant of a first filter, and x1 is an initial signal outputted from the first filter.

33. The method of claim 32, wherein the first filter comprises a low pass filter (LPF).

34. The method of claim 33, wherein the first filter is a primary filter.

35. The method of claim 27, wherein the second filter comprises at least one band pass filter (BPF).

36. The method of claim 35, wherein the BPF is a secondary filter.

37. The method of claim 35, wherein the second filter comprises a plurality of N BPFs and an (N)th output from the (N)th BPF is determined by: zN″+αBNzN′+ωBN2zN=ωBN2zN-1 wherein, zN-1 is an output from an (N−1)th BPF, that is, an input to the (N)th BPF, αBN is an attenuation constant, ωBN is a resonating frequency and zN is an output from the (N)th BPF.

38. The method of claim 37, wherein the second filter comprises at least one LPF.

39. The method of claim 38, wherein the LPF of the second filter is a secondary filter.

40. The method of claim 39, wherein the LPF of the second filter is disposed between the first filter and the plurality of N BPFs.

41. The method of claim 40, wherein the second filter comprises a plurality of M, LPFs and an output from an (M)th LPF of the second filter is determined by: yM″+αLMyM′+ωLM2yM=ωLM2yM-1 wherein, yM-1 is an output from an (M−1)th LPF, that is, an input to the (M)th LPF, αLM is an attenuation constant, ωLM is a resonating frequency, and yM is an output from the (M)th LPF.

42. The method of claim 41, wherein the plurality of M LPFs and the plurality of N BPFs of the second filter have different delay phase widths and gains.

43. The method of claim 42, wherein N and M are predetermined numbers so that a phase of a signal passing a loop of the nonlinear element, the first filter and the second filter corresponds to a multiple of 2π.

44. The method of claim 27, wherein the wideband signal comprises a chaotic signal having the plurality of frequency components in the predetermined range of frequency band.