Soft Iterative Decision Directed Channel Estimation for OFDM systems employing adaptive predictor

Soft iterative decision directed channel estimation (DDCE) employing fast data projection method (FDPM) subspace tracking algorithm and variable step size normalized least mean square-based predictor is proposed for OFDM system in this paper. A more realistic fractionally spaced channel impulse response (FS-CIR) model is considered. The performance of the soft iterative DDCE employing FDPM subspace tracking algorithm is validated in comparison with DDCE employing deflated version of projection approximation subspace tracking (PASTd) algorithm through computer simulations. The simulation results show that the soft iterative DDCE scheme based on FDPM algorithm outperformed its counterpart based on PASTd algorithm under both slow and fast fading channel scenarios. The proposed VSSNLMS-based CIR predictor for the iterative DDCE scheme also brings about an improved performance in comparison with the iterative scheme employing NLMS-based predictor.