Communication device

1 . A communication device comprising:

an interrogator configured to output an interrogation signal in which a plurality of unit chirp signals are repeated with a predetermined period; and

a backscatter tag configured to provide a tag signal formed by frequency modulation on the interrogation signal, and

wherein the interrogator is further configured to mix a received signal including the tag signal provided by the backscatter tag with the interrogation signal to generate an intermediate signal, perform a Fourier transform on the intermediate signal or a signal filtered from the intermediate signal, and demodulate the tag signal from frequency components excluding noise bins determined according to a predetermined rule among the components generated by the Fourier transform.

2 . The communication device of claim 1 , wherein the backscatter tag communicates with the interrogator through channels determined according to distances between the interrogator and the backscatter tag.

3 . The communication device of claim 1 , wherein the interrogation signal belongs to a millimeter wave band.

4 . The communication device of claim 1 , wherein the interrogator performs Fourier transform on the intermediate signal, the intermediate signal includes:

clutter noise periodically positioned; and

a tag signal component positioned without overlapping the clutter noise in a frequency domain.

5 . The communication device of claim 1 , wherein the signal generated by demodulating the tag signal provided by the backscatter tag includes frequency component corresponding to a moving distance of the interrogation signal between the interrogator and the backscatter tags.

6 . The communication device of claim 5 , wherein the signal generated by demodulating the tag signal provided by the backscatter tag further includes a frequency component corresponding to a frequency at which the interrogation signal is modulated.

7 . The communication device of claim 1 , wherein:

the communication device includes a plurality of backscatter tags;

the interrogator provides a single interrogation signal; and

the interrogator receives a plurality of tag signals formed by modulating, by the plurality of backscatter tags, the single interrogation signal and performs simultaneous communication with the plurality of backscatter tags.

8 . The communication device of claim 4 , in the communication device, wherein the clutter noise is in noise bins of the frequency domain, and the tag signal component is in tag bins of the frequency domain.

9 . The communication device of claim 1 , wherein the interrogation signal is constituted by N periodic unit chirp signals, and the tag signal is in N−1 discrete frequency bins per channel.

10 . The communication device of claim 1 , wherein the backscatter tag is configured to frequency-modulate the interrogation signal received by the backscatter tag from the interrogator, without information about a channel allocated to the backscatter tag, and provide the frequency-modulated output signals as the tag signal.

11 . The communication device of claim 1 , wherein the plurality of unit chirp signals are phase continuous.

12 . The communication device of claim 1 , wherein the interrogator comprises

a demodulation unit configured to demodulate the tag signal, and

the demodulation unit comprises:

a mixer configured to mix the interrogation signal with the received signal including a tag signal formed by frequency-modulating the interrogation signal by a backscatter tag to generate an intermediate signal;

a Fourier transform unit configured to Fourier-transform the intermediate signal; and

a filter configured to block the frequency component, among the intermediate signal, corresponding to the sum of the frequencies of the tag signal and the frequencies of the interrogation signal.

13 . The communication device of claim 1 , wherein the interrogator comprises a demodulation unit configured to demodulate the tag signal, and

the demodulation unit comprises:

a filter configured to receive the intermediate signal and pass a signal component having a frequency corresponding to a difference between the frequencies of the interrogation signal and the frequencies of the tag signal.

14 . The communication device of claim 8 , wherein the tag signal is in one or more tag bins, and are spaced a frequency at which the backscatter tag modulates, from a plurality of noise bins respectively adjacent to the one or more tag bins.

15 . The communication device of claim 14 , wherein the interrogator comprises a demodulation unit configured to demodulate the tag signal,

and when the backscatter tag is moving, the demodulation unit tracks signals of the moving backscatter tag by tracking signals spaced the frequency modulated by the backscatter tag, from the plurality of noise bins.

16 . The communication device of claim 1 , wherein the backscatter tag is included in Internet-of-Things (IOT) device.

17 . The communication device of claim 1 , wherein the backscatter tag operates with power collected by energy harvesting.

18 . The communication device of claim 1 , wherein the backscatter tag operates with power provided by battery.

19 . An interrogator comprising:

a signal generator configured to output an interrogation signal in which a plurality of unit chirp signals are repeated with a predetermined period; and

a demodulation unit;

wherein the demodulation unit comprises:

a mixer configured to mix a received signal including a tag signal formed by frequency-modulating the interrogation signal by a predetermined backscatter tag with the interrogation signal to generate an intermediate signal; and

a Fourier transformer configured to perform a Fourier transform on the intermediate signal or a signal filtered from the intermediate signal,

wherein the demodulation unit is further configured to demodulate the tag signal from frequency components excluding noise bins determined according to a predetermined rule among the components generated by the Fourier transform.

20 . A communication method in which an interrogator including a signal generator and a demodulate unit communicates with a backscatter tag, the method comprising:

outputting, by the signal generator, an interrogation signal in which a plurality of unit chirp signals are repeated with a predetermined period;

mixing, by the demodulation unit, a received signal including a tag signal formed by frequency-modulating the interrogation signal by the backscatter tag with the interrogation signal to generate an intermediate signal;

performing, by the demodulation unit, a Fourier transform on the intermediate signal or a signal filtered from the intermediate signal; and

demodulating, by the demodulation unit, the tag signal from frequency components excluding noise bins determined according to a predetermined rule among the components generated by the Fourier transform.