  We propose a novel receiver for orthogonal frequency division multiplexing
(OFDM) transmissions in impulsive noise environments. Impulsive noise arises in
many modern wireless and wireline communication systems, such as Wi-Fi and
powerline communications, due to uncoordinated interference that is much
stronger than thermal noise. We first show that the bit-error-rate optimal
receiver jointly estimates the propagation channel coefficients, the noise
impulses, the finite-alphabet symbols, and the unknown bits. We then propose a
near-optimal yet computationally tractable approach to this joint estimation
problem using loopy belief propagation. In particular, we merge the recently
proposed "generalized approximate message passing" (GAMP) algorithm with the
forward-backward algorithm and soft-input soft-output decoding using a "turbo"
approach. Numerical results indicate that the proposed receiver drastically
outperforms existing receivers under impulsive noise and comes within 1 dB of
the matched-filter bound. Meanwhile, with N tones, the proposed
factor-graph-based receiver has only O(N log N) complexity, and it can be
parallelized.
