METHOD FOR TIME SYNCHRONIZATION AND CARRIER FREQUENCY OFFSET COMPESATION IN OPTICAL OFDM SYSTEM

摘要

Disclosed are a method and an apparatus for a time synchronization and a carrier frequency offset compensation in an optical OFDM system. The disclosed apparatus comprises: a receiving portion for receiving an OFDM symbol where a first training symbol and a second training symbol are inserted; a fractional frequency offset estimation portion for estimating a fractional frequency offset by using the first training symbol; a time synchronization portion for carrying out the time synchronization by using the first training symbol; an integer frequency offset estimation portion for estimating an integer frequency offset by using the first training symbol and the second training symbol after a compensation for the estimated fractional frequency offset and the time synchronization are done; and an offset compensation portion for compensating the estimated fractional frequency offset and the estimated integer frequency offset. The first training symbol is inserted in front of the OFDM symbol, and the second training symbol is inserted between the first training symbol and the OFDM symbol. The first training symbol has a structure that one unit symbol is repeated twice. The first training symbol and the second training symbol have mutually different frequencies. The disclosed apparatus and the method have an advantage of estimating and compensating the integer frequency offset and the fractional frequency offset at once with a simple DSP calculation without a complicated hardware such as PLL.