Based on the constellation diagram of the different modulations, a novel S and Π-decision rule is designed for the analog demapper of the orthogonal frequency-division multiplexing (OFDM) systems. The dedicated short-range communications (DSRC) system is chosen as an OFDM platform to compare the performance among the proposed S and Π-decision decoder, hard-decision and soft-decision decoders. Simulation results demonstrate that both the complexity and performance of S and Π-decision demapper

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... d for M-ary quadrature amplitude modulation (QAM) OFDM system can be greatly improved. The number of decisions between the received symbol and constellation points can be simplified to look up table 2 log M times for M-ary QAM OFDM system.