MULTIRESOLUTION TRANSMISSION WITH MULTICARRIER SIGNALS

摘要

A transmitter communicates data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, the OFDM symbols including a plurality of sub-carrier symbols formed in the frequency domain for modulating with the data to be carried and pilot symbol sub-carriers and the transmitter is arranged to form a Multiple Input Multiple Output (MIMO) scheme. The transmitter includes a modulator arranged in operation to receive on a first input, national broadcast data symbols to receive on a second input, local service data symbols and to modulate the data bearing sub-carrier signals of the OFDM symbols with either the national broadcast data symbols or the local service data symbols and the national broadcast symbols. The modulation of the data bearing sub-carrier signals of the OFDM symbols with the national broadcast data symbols is performed by mapping the data symbols according to a first modulation scheme, and the modulation of the sub-carrier signals of the OFDM symbols with the local service data symbols and the national broadcast data symbols is performed by mapping the national broadcast data symbols and the local service data symbols according to a second modulation scheme. A ?G?? encoder is arranged to receive the OFDM symbols and to form at least first and second versions of the OFDM symbols, a frequency interleaver is arranged to receive the first and second versions of the OFDM symbols and to interleave the position of the respective modulated sub-carriers; and a pilot signal inserter is arranged to receive the first and second version of the OFDM symbols and to insert first pilot symbols at the pilot sub-carriers of the first version of the OFDM symbols and second pilot symbols at the pilot sub-carriers of the second version of the OFDM symbols. If the modulator is arranged to modulate the data bearing sub-carriers with both the local service data symbols and the national broadcast symbols, the modulator is arranged to generate local pilot symbols at predetermined locations within the first and second OFDM symbols, to de-interleave the local pilot symbols from the locations within the first and second OFDM symbols, the de- interleaving being a reverse mapping of the interleaving performed by the frequency interleaver, and to include the local pilot symbols with the local service data symbols at the locations determined by the de-interleaving.