Coded modulation for noncoherent reception with application to OFDM

Power- and bandwidth-efficient differentially encoded transmission over slo wly time-varying fading channels with noncoherent reception and without cha nnel state information is considered. For high bandwidth efficiencies, comb ined phase and amplitude modulation is used. For increased power efficiency , channel coding and multiple-symbol differential detection are applied, i. e., interleaving and detection are based on blocks of N > 2 consecutive sym bols. The presented concepts are directly applicable to transmission over f lat fading channels. However, concentrating on the situation of frequency-s elective channels, we consider their application to multicarrier transmissi on using orthogonal frequency-division multiplexing (OFDM). When coding acr oss subcarriers, OFDM transforms the actual frequency-selective channel int o a slowly time-varying frequency-nonselective fading channel. This paper p resents a design for multilevel coding schemes to approach theoretical limi ts for power- and bandwidth-efficient noncoherent transmission over the equ ivalent fading channel. It is shown that bit-interleaved coded modulation, which relies on Gray labeling, is competitive only in the case of conventio nal differential detection with N = 2. The theoretic considerations are wel l approved by simulation results, where turbo codes are applied as componen t codes.