MULTIRESOLUTION TRANSMISSION WITH MULTICARRIER SIGNALS

摘要

An OFDM transmitter preferably for use with a Next Generation Handheld (NGH) standard comprises: a first input from a first data pipe 82 according to a national broadcast channel; a second input from a local service insertion data pipe 84 according to a local service channel; and a modulator which modulates the sub-carrier signals of OFDM symbols with either the data symbols from the first data pipe y0y1y2y3, using a first lower order modulation scheme 94 (e.g. M-QAM), or the data symbols form the first data pipe and the local service insertion data pipe h0h1, using a second higher order modulation scheme 96 (e.g. at least 2M-QAM). The OFDM symbols include a plurality of sub-carrier symbols including symbols to be modulated with pilot sub-carriers. Local pilots may be inserted into the local service data by puncturing the local service data symbols by replacing the local service data symbols with local pilot symbols.