On the design of MLC-LDPC-OFDM in DRM MF and HF channels

Orthogonal Frequency Division Multiplexing (OFDM), aided by proper channel coding schemes, can realize very dependable transmission in fading channels. For the purpose of improving the performance of the OFDM based DRM digital AM broadcasting in MF and HF channels, this paper designs MLC-LDPC-OFDM transmission scheme that is suitable for MF and HF channels. The equivalent channel capacities of MLC-LDPC-OFDM with two different decoding strategies, namely IMSD and PDL, are analyzed, basing on which this paper redesigns the code rates of MLC. In addition, the calculation of likelihood ratio in LDPC decoding is modified according to channel models. The simulation results show that the proposed schemes have better performance than the existing ones in MF and HF channels.