HMM modeling for OFDM–BER performance

OFDM based systems widely adopted in several wired and wireless standards can be analyzed efficiently with reduced cost, time and computation by characterizing the realistic physical layer with a Finite State Markov Channel. In this paper, accurate HMMs have been derived using BWA for a wide range of channel SNR conditions and different OFDM system parameters such as number of subcarriers, FFT size and number of symbols. OFDM with pilot based channel estimation errors have also been accurately parameterized for the symbol error rate. All estimated error statistics have been validated by comparison in terms of log likelihood, average error probability, autocorrelation function and the distributions of error or error free interval. Sequences from higher order modulation in OFDM systems can be reproduced with relatively fewer HMM states. The reliability of the model is confirmed by an excellent match to those of the underlying OFDM based physical layer. Accuracy of the ACF comparisons with number of HMM states has also been quantified.