Abstract: A transmission apparatus of a single carrier-based wireless communication system is proposed. The transmission apparatus may include a transceiver, a memory configured to store one or more instructions; and a processor configured to execute the one or more instructions stored in the memory. The processor may generate data symbols by modulating traffic data, generate a cyclic prefix (CP) on the basis of the data symbols, and generate a pilot symbol for the data symbol. The transceiver may transmit a single carrier frequency domain equalizer (SC-FDE) frame including the data symbol, the CP, and the pilot symbol. The data symbols may include first data symbols and second data symbols. The pilot symbol may be transmitted after transmission of the first data symbols and before transmission of the second data symbols.

Abstract: Disclosed is a method for fabricating an optical fiber preform using a double torch in MCVD, which includes a first process of heating a quartz tube (10) at a temperature lower than a sintering temperature by using a first torch (21) with putting reaction gas, oxygen gas and dehydration gas into the tube so that soot particles are generated and deposited, and heating the tube to a predetermined temperature by using a second torch (22) spaced apart from the first torch after the first torch (21) passes so that moisture in the soot particles is removed; and a second process of conducting dehydration for removing moisture in the soot particles by use of the first torch (21) again, and heating the tube above a sintering temperature by using the second torch (22) so that the soot particles free from moisture are vitrified.