Bayesian blind turbo receiver for coded OFDM systems with frequency offset and frequency-selective fading

The design of a blind receiver for coded orthogonal frequency-division multiplexing (OFDM) communication systems in the presence of frequency offset and frequency-selective fading is investigated. The proposed blind receiver iterates between a Bayesian demodulation stage and a maximum a posteriori (MAP) channel decoding stage; and the extrinsic a posteriori probabilities of data symbols are iteratively exchanged between these two stages to achieve successively improved performance. The Bayesian demodulator computes the a posteriori data symbol probabilities, based on the received signals (without knowing or explicitly estimating the frequency offset and the fading channel states), by using Markov chain Monte Carlo (MCMC) techniques. In particular, two MCMC methods, namely, the Metropolis-Hastings algorithm and the Gibbs sampler, are studied for this purpose. Computer simulation results show that the proposed Bayesian blind turbo receiver can achieve good performance and it is robust against modeling mismatch