Iterative OFDM receiver with Decision Directed Channel Estimation

Iterative technique at any communication receiver has been confirmed to exhibit some gains over its non-iterative counterpart. In this paper, we consider a turbo-coded OFDM system employing Iterative receiver that comprises of Turbo decoder and the Iterative decision directed channel estimation (DDCE) scheme that are working together in an iterative mode. The iterative DDCE scheme is based on the fast data projection method (FDPM)-based channel impulse response (CIR) estimator and the normalized least mean square (NLMS)-based adaptive predictor. The performance of the Iterative DDCE is compared, through computer simulation, with the non-Iterative DDCE operating on a non-iterative receiver. It was found that the former outperformed the latter. The iterative DDCE employing FDPM based-CIR estimator is also compared with another one employing a popular subspace tracking algorithm, the projection approximation subspace tracking with deflation (PASTd) algorithm. It was also found that the proposed Iterative DDCE employing FDPM-based CIR estimator exhibited performance gain over the iterative DDCE employing PASTd based-CIR estimator.