Method for receiving signal in wireless optical communication system, and receiving terminal therefor

1. A first user equipment (UE) for receiving a signal in optical wireless communication comprising:

a transceiver configured to receive an optical signal of an orbital angular momentum (OAM) mode from a second UE;

an OAM demultiplexer;

a demodulator composed of at least one phase shifter;

an optical-to-electrical (O-to-E) converter composed of at least one photodiode; and

a processor connected to the transceiver, the demodulator, and the O-to-E converter,

wherein the OAM demultiplexer performs beam split of the optical signal such that each of the demodulator and the O-to-E converter decodes at least one OAM mode applied to the optical signal,

wherein the at least one phase shifter converts the optical signal of the OAM mode into an optical signal of a Gaussian mode; and

wherein the at least one photodiode converts the optical signal of the Gaussian mode into an electrical signal.

2. The first UE according to claim 1 , wherein:

the at least one phase shifter is a phase shifter array that forms respective regions in the demodulator,

wherein the phase shifter array individually controls the optical signals of the OAM mode reaching the respective regions.

3. The first UE according to claim 1 , wherein:

the at least one photodiode is a photodiode array that forms respective regions in the O-to-E converter,

wherein respective electrical signals converted through the photodiode array are summed and processed by the processor.

4. The first UE according to claim 1 , further comprising:

a phase error corrector, wherein the phase error corrector compensates for a change in wavefront of the optical signal received through the transceiver.

5. The first UE according to claim 1 , further comprising:

an average interference tracker (AIT), wherein the average interference tracker (AIT) measures interference generated in the electrical signal converted through the O-to-E converter, and removes the measured interference from the electrical signal.

6. The first UE according to claim 1 , further comprising:

a laser oscillator configured to generate a reference optical resource of a frequency promised with the second UE; and

a coupler configured to mix and branch the reference optical resource and the optical signal,

wherein the at least one photodiode outputs a difference in current between optical signals branched by the coupler.

7. A method for receiving a signal by a first user equipment (UE) in optical wireless communication comprising:

receiving an optical signal of an orbital angular momentum (OAM) mode from a second UE;

performing beam split of the optical signal through an OAM demultiplexer such that each of a demodulator and an optical-to-electrical (O-to-E) converter decodes at least one OAM mode applied to the optical signal,

converting the optical signal of the OAM mode into an optical signal of a Gaussian mode through a demodulator composed of at least one phase shifter; and

converting the optical signal of the Gaussian mode into an electrical signal through the O-to-E converter composed of at least one photodiode.

8. The method according to claim 7 ,

wherein the at least one phase shifter is a phase shifter array that forms respective regions in the demodulator, and

wherein the optical signals of the OAM mode reaching the respective regions are individually controlled by the phase shifter array.

9. The method according to claim 7 ,

wherein the at least one photodiode is a photodiode array that forms respective regions in the O-to-E converter, and

wherein respective electrical signals converted through the photodiode array are summed and processed by the processor.

10. The method according to claim 7 , further comprising:

by a phase error corrector, compensating for a change in wavefront of the optical signal received through a transceiver.

11. The method according to claim 7 , further comprising:

by an average interference tracker, measuring interference generated in the electrical signal converted through the O-to-E converter, and removing the measured interference from the electrical signal.

12. The method according to claim 7 , further comprising:

by a laser oscillator, generating a reference optical resource of a frequency promised with the second UE;

by a coupler, mixing and branching the reference optical resource and the optical signal; and

by the at least one photodiode, outputting a difference in current between optical signals branched by the coupler.