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Performance of Pilot-Based EM Channel Estimation for OFDM Systems

In this work, pilot-based expectation-maximization (EM) channel estimation for OFDM systems are studied by considering different pilot placements. In the first method, the pilot symbols are distributed at certain locations in the OFDM lime-frequency lattices to find appropriate initial values. In the second method, the pilot symbols are placed in the first OFDM symbol and then a sequential channel estimation is applied. These two methods are compared and the performances are studied in terms of mean square error and bit error rate. Moreover, the number of iterations used in the algorithm are given to compare the complexity of the methods.