TWO-DIMENSIONAL SPREADING SYSTEM FOR OFDM-CDM SYSTEM

摘要

PPROBLEM TO BE SOLVED: To provide a two-dimensional spreading system capable of maximizing a diversity gain regardless of a channel environment in an OFDM-CDM system. PSOLUTION: A transmitter in a communication system based on OFDM-CDM according to the present invention comprises: a frequency spreader which multiplies symbols to be transmitted by a frequency spreading factor and outputs the frequency spread symbols whose number corresponds to the frequency spreading factor; buffers, whose number corresponds to the frequency spreading factor, for temporarily storing just the frequency spread symbols in a unit of a predefined number of symbols; a time spreader which multiplies parallel frequency spread symbols from the buffers by a time spreading factor and outputs frequency-time spread symbols; an inverse fast Fourier transform (IFFT) processor which performs IFFT on the parallel frequency-time spread symbols outputted from the time spreader and outputs an OFDM symbol; a guard interval (GI) inserter which inserts a GI into a signal outputted from the IFFT processor and transfers the signal. PCOPYRIGHT: (C)2007,JPO&INPIT