A receiver for recovering local service data symbols from OFDM symbols in the presence of OFDM symbols carrying national broadcast data symbols.

摘要

A receiver for recovering local service data symbols from first OFDM symbols, from a first modulation scheme, carrying national broadcast data symbols and local service data symbols in the presence of second OFDM symbols, from a second modulation scheme, carrying national broadcast data symbols only. First and second OFDM symbols include the same pilot sub-carrier symbols and the first OFDM symbols include local pilot symbols. An OFDM detector recovers local service modulation symbols from the data bearing sub-carriers of the first OFDM symbols wherein the detector includes an equalizer for recovering the local service modulation symbols of the first modulation scheme by: using the pilot sub-carrier symbols to estimate a combined channel (Hn(z) + Hl(z)) (n = national broadcast signal path, l = local service signal path); estimating national broadcast modulation symbols from the second OFDM symbols, s1; estimating a convolution of the combined channel and the national broadcast modulation symbols, s4; forming an intermediate result (D(z)Hl(z)), s6; using local pilot symbols to estimate the channel via which the first OFDM symbols were received, s8; estimate local service modulation symbols (D(z)) by dividing D(z)Hl(z) by Hl(z).