EM Channel Estimation for Coded OFDM Transmissions over Frequency-Selective Channel

We derive expectation-maximization (EM) based iterative algorithms to estimate the impulse response of multipath channel with coded OFDM system. We compare two ways for choosing EM complete data: a complete data built from observations and transmitted symbols (CL-EM) and complete data chosen by decomposing noise and observation components (NCD-EM). We also derive the Cramer-Rao lower bound (CRB) for coded OFDM transmission. Simulation results show that CLEM has better convergence than NCD-EM and achieves the CRB.