1. Field
Apparatuses and methods consistent with exemplary embodiments relate to transmitting and receiving signal frames using an orthogonal frequency division multiplexing (OFDM) method.
2. Description of the Related Art
Digital Video Broadcasting the Second Generation Terrestrial (DVB-T2) is a second generation European terrestrial digital broadcasting standard that is established by improving a performance of DVB-T which currently serves as a standard in 35 or more nations including Europe and have started. The DVB-T2 uses newest technologies such as low density parity check (LDPC) codes, 256 quadrature amplitude modulation (256 QAM) modulation method, etc. to increase a transmission capacity and realize high bandwidth efficiency. Therefore, various high-quality services such as a high-definition television (HDTV), etc. may be provided in a limited band.
A T2-frame that is currently used in the DVB-T2 includes a P1 preamble symbol, a P2 preamble symbol, and a data symbol. The P1 preamble symbol is used to perform synchronization and transmit signaling data. A receiver detects the P1 preamble symbol, performs synchronization by using the detected P1 preamble symbol, compensates for frequency offset, and obtains the signaling data from the P1 symbols.
However, a process of performing synchronization by using the P1 preamble symbol is performed based on the signaling data of the P1 preamble symbol.
FIG. 1 is a view illustrating that sub-carriers with which the signaling data of P1 preamble symbol is matched are randomly arranged. In other words, referring to FIG. 1, the sub-carriers with which the signaling data of the P1 preamble symbol is matched are not arranged at uniform intervals but are randomly arranged. Therefore, if synchronization is performed based on the signaling data of the P1 preamble symbol, it is difficult to accurately detect a preamble start point within one sample.
Also, the sub-carriers with which the signaling data of the P1 preamble symbol is matched are not arranged at the uniform intervals to be used as reference signals. Therefore, a channel estimation may not be performed.
Therefore, there is a need for a reference signal that accurately detects a preamble start point within one sample, measures frequency offset, and estimates a channel.