Apparatus and method for compensating optical transmission delay

1. A method of optical transmission delay compensation of a system comprising a main unit and a remote unit, wherein the main unit and the remote unit are connected to each other through an optical transmission line, the method comprising:

receiving a reference signal, by the remote unit, generated by the main unit through the optical transmission line;

analog converting the reference signal and performing analog processing on the reference signal;

converting the analog-processed reference signal into an RF signal and radiating the RF signal; and

measuring a delay time until the reference signal is generated and radiated as the RF signal,

wherein the main unit receives a first GPS signal, and the remote unit receives a second GPS signal,

wherein the first GPS signal is transmitted to the remote unit together with the reference signal, and

wherein the measuring of the delay time comprises measuring the delay time using the first GPS signal and the second GPS signal.

2. The method of claim 1 , wherein the analog converting comprises:

converting the reference signal into an analog signal, and

the analog processing comprises at least one of amplification, conversion, operation, and noise removal of the analog signal.

3. The method of claim 1 , wherein the measuring of the delay time comprises:

generating a response signal corresponding to a time when the RF signal is radiated and transmitting the response signal to the main unit,

wherein the main unit is configured to measure the delay time using the response signal.

4. The method of claim 1 , further comprising:

receiving a data signal, by the remote unit, compensated for by the delay time by the main unit from the main unit.

5. The method of claim 1 , wherein a number of the reference signal is more than one and phases of reference signals are different from each other, and

the remote unit generates a synchronization detection window, and

the measuring of the delay time comprises:

measuring the delay time by detecting one of the reference signals through the synchronization detection window.

6. The method of claim 1 , wherein the remote unit generates a plurality of synchronization detection windows, and

the measuring of the delay time further comprises:

measuring the delay time by using a window for detecting the reference signal from among the plurality of synchronization detection windows.

7. The method of claim 1 , further comprising:

compensating for a data signal by the delay time by the remote unit.

8. A system including a plurality of remote units connected to a main unit through an optical transmission line and receiving a reference signal generated by the main unit,

wherein each of the plurality of remote units comprises:

an analog converter configured to convert the reference signal into an analog signal;

an analog processor configured to perform analog processing on the analog signal;

an RF transceiver configured to convert the analog-processed analog signal into an RF signal and radiating the RF signal;

a GPS receiver configured to receive a GPS signal; and

a delay time processor configured to measure a delay time until the reference signal is generated and radiated as the RF signal, using the GPS signal.

9. The system of claim 8 , wherein the delay time processor is configured to transmit the delay time to the main unit.

10. The system of claim 8 , wherein a number of the reference signal is more than one and phases of reference signals are different from each other, and

the delay time processor is configured to generate a synchronization detection window and to measure the delay time by detecting one of the reference signals through the synchronization detection window.

11. The system of claim 10 , wherein the delay time processor is configured to compensate for a data signal received from the main unit by the delay time.

12. The system of claim 8 , wherein the delay time processor is configured to generate a plurality of synchronization detection windows having different phases and to measure the delay time through a window for detecting the reference signal from among the plurality of synchronization detection windows.