Hierarchical OFDM system.

摘要

A digital transmission system capable of a hierarchical transmission in an quadrature frequency multiplex modulation, a modulating apparatus and a demodulating apparatus therefor ar provided. The hierarchical information transmission system includes, means for constructing a frame comprised of a plurality of symbols in an quadrature frequency multiplex signal transmission system that transmits a plurality of hierarchical information data using a modulation form with respectively different C/N ratios as required, means for performing the interleavings in both of the time and frequency domains, between the data using respective modulation forms within the frame, and means for making the respective modulation forms to associate with respective predetermined carriers. <IMAGE>