EM-based channel estimation for OFDM

Estimating a channel that is subject to frequency selective Rayleigh fading is a challenging problem in an orthogonal frequency division multiplexing (OFDM) system. We propose an EM-based iterative algorithm to efficiently estimate the channel impulse response (CIR) of an OFDM system. This algorithm is capable of improving the channel estimate by making use of pilot tones to obtain the initial estimate for iterative steps. Simulation results show that the bit error rate (BER) can be significantly reduced by this algorithm.