Performance of EM-based channel estimation for STBC-OFDM systems

In this study, a frequency domain Expectation-Maximization (EM) based channel estimation which estimates the channel coefficients subcarrier by subcarrier is proposed for Space Time Block Coded Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems. As initial channel estimation pilot symbols are used and sequential channel estimation is performed with few pilot symbols in order to use bandwidth efficiently. It is compared to the time domain EM based channel estimation algorithm which needs matrix inversion and seen that the proposed algoritm decreased the complexity without any performance loss. The performance comparison of these algorithms are studied in terms of bit-error rate (BER), minimum-squared error (MSE) and the number of iterations used in the EM algorithm.