Systems and methods for communicating by modulating data on zeros
View Patent ↗Systems and methods for transmitting data using various Modulation on Zeros schemes are described. In many embodiments, a communication system is utilized that includes a transmitter having a modulator that modulates a plurality of information bits to encode the bits in the zeros of the z-transform of a discrete-time baseband signal. In addition, the communication system includes a receiver having a decoder configured to decode a plurality of bits of information from the samples of a received signal by: determining a plurality of zeros of a z-transform of a received discrete-time baseband signal based upon samples from a received continuous-time signal, identifying zeros that encode the plurality of information bits, and outputting a plurality of decoded information bits based upon the identified zeros.
1. A combined radar and wireless communication system, comprising:
a transmitter configured to transmit a continuous-time signal, comprising:
a modulator configured to modulate a plurality of bits to obtain a discrete-time baseband signal that is a Huffman sequence selected from a codebook comprising a plurality of Huffman sequences; and
a signal generator configured to generate the continuous-time signal based upon the discrete-time baseband signal;
a receiver, comprising:
a demodulator configured to sample a received continuous-time signal at a given sampling rate; and
a decoder configured to decode a plurality of received information bits from the samples of the received signal using the codebook;
wherein the transmitter further comprises a radar receiver configured to receive a reflection of the continuous-time signal and perform detection and ranging based upon impulsive autocorrelation of the selected Huffman sequence.
2. The combined radar and wireless communication system of claim 1 , wherein:
the z-transform of the discrete-time baseband signal comprises a zero for each of the plurality of bits;
each zero in the z-transform of the discrete-time baseband signal is limited to being one of a set of conjugate-reciprocal pairs of zeros; and
the conjugate reciprocal pair of zeros in the set of conjugate-reciprocal pairs of zeros are uniformly placed on two circles:
an outer circle having a radius greater than one; and
an inner circle having a radius that is the reciprocal of the first radius.
3. The combined radar and wireless communication system of claim 2 , wherein the decoder is configured to decode the plurality of decoded information bits by:
determining a plurality of zeros of a z-transform of a received discrete-time baseband signal based upon samples from the received continuous-time signal;
identifying zeros from the plurality of zeros that correspond to information bits; and
outputting the plurality of received information bits based upon the identified zeros.
4. The combined radar and wireless communication system of claim 3 , wherein the plurality of zeros of the z-transform of the received discrete-time baseband signal comprise a plurality of zeros that correspond to information bits and at least one zero introduced by multipath propagation of the transmitted signal.
5. The combined radar and wireless communication system of claim 3 , wherein the decoder is configured to determine the most likely set of zeros for the z-transform of the discrete-time baseband signal used to generate the transmitted signal based upon the samples of the received continuous-time signal.
6. The combined radar and wireless communication system of claim 3 , wherein the codebook is an autocorrelation codebook.
7. The combined radar and wireless communication system of claim 3 , wherein the decoder determines the decoded information bits by performing a weighted comparison of samples of the z-transform of the received discrete-time baseband signal with each zero in a set of zeros.
8. The combined radar and wireless communication system of claim 1 , wherein the decoder performs a weighted comparison using an inverse discrete Fourier transform of delayed and weighted samples of the received continuous-time signal.
9. The combined radar and wireless communication system of claim 1 , wherein the receiver is configured to estimate characteristics of a channel over which the received continuous-time signal was transmitted.
10. The combined radar and wireless communication system of claim 1 , wherein:
the receiver comprises a plurality of receive antennas; and
the decoder determines the decoded information bits based upon a plurality of continuous-time signals received by the plurality of receive antennas.
11. The combined radar and wireless communication system of claim 1 , wherein the continuous-time transmitted signal comprises a carrier frequency modulated based upon the discrete-time baseband signal.
12. The combined radar and wireless communication system of claim 1 , wherein the demodulator comprises an analog to digital converter.
13. A combined radar and wireless communication system, comprising:
a transmitter configured to transmit a continuous-time signal, comprising:
a modulator configured to modulate a plurality of bits to obtain a discrete-time baseband signal that is a Huffman sequence; and
a signal generator configured to generate the continuous-time signal based upon the discrete-time baseband signal;
a radar receiver configured to receive a reflection of the continuous-time signal and perform detection and ranging based upon impulsive autocorrelation of the Huffman sequence;
wherein the continuous-time transmitted signal comprises a carrier frequency modulated signal based upon the discrete-time baseband signal.
14. The combined radar and wireless communication system of claim 13 , wherein:
the z-transform of the discrete-time baseband signal comprises a zero for each of the plurality of bits;
each zero in the z-transform of the discrete-time baseband signal is limited to being one of a set of conjugate-reciprocal pairs of zeros; and
the conjugate reciprocal pair of zeros in the set of conjugate-reciprocal pairs of zeros are uniformly placed on two circles:
an outer circle having a radius greater than one; and
an inner circle having a radius that is the reciprocal of the first radius.
15. The combined radar and wireless communication system of claim 13 , wherein modulator is configured to select the Huffman sequence from a codebook comprising a plurality of Huffman sequences based upon the plurality of bits.
16. The combined radar and wireless communication system of claim 13 , wherein the modulator is configured to modulate the plurality of bits to obtain the discrete-time baseband signal using a lookup mechanism.
17. A combined radar and wireless communication system, comprising:
a transmitter configured to transmit a continuous-time signal, comprising:
a modulator configured to modulate a plurality of bits to obtain a discrete-time baseband signal; and
a signal generator configured to generate the continuous-time signal based upon the discrete-time baseband signal;
a radar receiver configured to receive a reflection of the continuous-time signal and perform detection and ranging based upon impulsive autocorrelation with the discrete-time baseband signal;
wherein the z-transform of the discrete-time baseband signal comprises a zero for each of the plurality of bits;
wherein each zero in the z-transform of the discrete-time baseband signal is limited to being one of a set of conjugate-reciprocal pairs of zeros;
wherein the conjugate reciprocal pair of zeros in the set of conjugate-reciprocal pairs of zeros are uniformly placed on two circles:
an outer circle having a radius greater than one; and
an inner circle having a radius that is the reciprocal of the first radius; and
wherein the continuous-time transmitted signal comprises a carrier frequency modulated signal based upon the discrete-time baseband signal.
18. The combined radar and wireless communication system of claim 17 , wherein:
the discrete time-baseband signal is a Huffman sequence; and
the modulator is configured to select the Huffman sequence from a codebook comprising a plurality of Huffman sequences based upon the plurality of bits.
19. The combined radar and wireless communication system of claim 17 , wherein the modulator is configured to modulate the plurality of bits to obtain the discrete-time baseband signal using a lookup mechanism.