Method and apparatus for obtaining angle information of reference signal

1. A method of acquiring angle information of a reference signal performed by a user equipment (UE), the method comprising:

receiving a reference signal from a base station comprising a plurality of patch antennas;

acquiring phase information depending on a carrier frequency of the reference signal based on received data of the reference signal measured at a plurality of sample times; and

calculating an angle of departure (AoD) of the reference signal based on the phase information depending on the carrier frequency and a distance between a first patch antenna and a second patch antenna of the plurality of patch antennas,

wherein the plurality of patch antennas comprises the first patch antenna configured to transmit a first subcarrier and the second patch antenna configured to transmit a second subcarrier different from the first subcarrier, and

the phase information depends on a sum of the carrier frequency and a difference between the first subcarrier and the second subcarrier.

2. The method of claim 1 , wherein a waveform of the reference signal is configured to be continuous in a time interval greater than a size of an orthogonal frequency division multiplexing (OFDM) symbol.

3. The method of claim 1 , wherein the plurality of patch antennas is configured to transmit subcarriers comprised in a predetermined subcarrier group and the subcarriers are provided at equal intervals in a frequency domain.

4. The method of claim 1 , wherein the acquiring of the phase information comprises:

acquiring a sample vector based on the received data of the reference signal;

calculating a phase vector by performing an inner product on a discrete Fourier transform (DFT) coefficient vector for a DFT operation with respect to the sample vector;

extracting a first sub-phase vector and a second sub-phase vector from the phase vector; and

extracting the phase information from a conjugate product from the first sub-phase vector and the second sub-phase vector.

5. The method of claim 4 , wherein the conjugate product of the first sub-phase vector and the second sub-phase vector comprises a conjugate product between a first component of the phase vector and a second component having an angular frequency index different from an angular frequency of the first component.

6. The method of claim 4 , wherein the conjugate product of the first sub-phase vector and the second sub-phase vector is independent from a local clock error between the UE and the base station.

7. A user equipment (UE) comprising:

a communicator; and

a processor,

wherein the processor is configured to perform a process of receiving a reference signal from a base station comprising a plurality of patch antennas, a process of acquiring phase information depending on a carrier frequency of the reference signal based on received data of the reference signal measured at a plurality of sample times, and a process of calculating an angle of departure (AoD) of the reference signal based on the phase information depending on the carrier frequency and a distance between a first patch antenna and a second patch antenna of the plurality of patch antennas,

wherein the plurality of patch antennas comprises the first patch antenna configured to transmit a first subcarrier and the second patch antenna configured to transmit a second subcarrier different from the first subcarrier, and

the phase information depends on a sum of the carrier frequency and a difference between the first subcarrier and the second subcarrier.

8. The UE of claim 7 , wherein a waveform of the reference signal is configured to be continuous in a time interval greater than a size of an orthogonal frequency division multiplexing (OFDM) symbol.

9. The UE of claim 7 , wherein the process of acquiring the phase information depending on the carrier frequency comprises:

a process of acquiring a sample vector based on the received data of the reference signal;

a process of calculating a phase vector by performing an inner product on a discrete Fourier transform (DFT) coefficient vector for a DFT operation with respect to the sample vector;

a process of extracting a first sub-phase vector and a second sub-phase vector from the phase vector; and

a process of extracting the phase information from a conjugate product from the first sub-phase vector and the second sub-phase vector.

10. The UE of claim 9 , wherein the conjugate product of the first sub-phase vector and the second sub-phase vector comprises a conjugate product between a first component of the phase vector and a second component having an angular frequency index different from an angular frequency of the first component.

11. The UE of claim 9 , wherein the conjugate product of the first sub-phase vector and the second sub-phase vector is independent from a local clock error between the UE and the base station.

12. A beam selection method performed by a base station, the beam selection method comprising:

setting a subcarrier group allocated to a plurality of patch antennas;

determining a reference signal sequence;

transmitting a reference signal based on the subcarrier group and the reference signal sequence;

acquiring information about an angle of departure (AoD) of the reference signal from a user equipment (UE); and

determining a beam to be transmitted to the UE based on information about the AoD of the reference signal,

wherein the AoD is determined based on phase information depending on a carrier frequency of the reference signal and a distance between a first patch antenna and a second patch antenna of the plurality of patch antennas,

wherein the plurality of patch antennas comprises the first patch antenna configured to transmit a first subcarrier and the second patch antenna configured to transmit a second subcarrier different from the first subcarrier, and

the phase information depends on a sum of the carrier frequency and a difference between the first subcarrier and the second subcarrier.

13. The beam selection method of claim 12 , wherein the reference signal sequence is configured such that a waveform of the reference signal is configured to be continuous in a time interval greater than a size of an orthogonal frequency division multiplexing (OFDM) symbol.

14. The beam selection method of claim 12 , wherein subcarriers comprised in the subcarrier group are provided at equal intervals in a frequency domain.