Optical network terminal, method for time syncronization thereof, optical line terminal, and method for managing network thereof

A method for time synchronization of an optical network terminal (ONT), which is a connection apparatus of a service provider of a passive optical network system, and an optical line terminal (OLT), which is a transmitting/receiving apparatus of a service provider of the passive optical network system, comprising:

• shifting to a ranging state;
• receiving a ranging request message that comprises a first current time of the optical line terminal from the optical line terminal;
• calculating a first compensation time when a transmission delay is compensated at a time that the ranging request message is received;
• transmitting a serial number response message to the optical line terminal;
• calculating a second compensation time when the transmission delay is compensated at a time that the serial number response message is transmitted;
• receiving a ranging time message that comprises a second current time when the serial number response message from the optical line terminal is received;
• calculating an offset time from the first current time, the second current time, the first compensation time, and the second compensation time;
• and
• synchronizing a clock of the optical network terminal and a clock of the optical line terminal based on the offset time.