A Decision-Directed Estimation of Time and Frequency Selective Channels for OFDM Systems

We propose in this paper a decision-directed channel estimation technique for OFDM systems operating in time and frequency selective channels. This technique exploits both frequency and time correlation of the channel transfer function. The frequency correlation is achieved by applying a Karhunen-Loeve (KL) expansion which performs the separation of the channel space from the noise space and generates an uncorrelated representation of the channel transfer function. At the output of the KL expansion stage, elementary linear single-input single-output (SISO) predictors are developed by exploiting the channel time correlation. The performance of the proposed estimation algorithm is assessed through computer simulations in out-door environment. Test results show that our technique presents a better performance compared with some basic decision-directed channel estimates.