Channel Estimation using Iterative Process for OFDMA based Wireless System

In this paper the channel estimation and data detection for OFDMA based systems over time varying frequency selective channels was described using a modified superimposed training (SIT) sequence method with iterative process. This method can be significantly improved the accuracy by exploiting time and frequency correlations between the channel frequency response coefficients (coherence time and coherence bandwidth).In SIT based channel estimation scheme, training sequence is arithmetically added to the data sequence with a desired power allocation ratio at the transmitter. And at the receiver the channel estimation is done by using the same SIT sequence, further the mean square error (MSE) is minimized with iterative process from detected data symbols. This method improves the system performance in terms of MSE and bit error rate (BER) for higher order modulation and high mobility cases