LSF-CMA Equalization Algorithm for OFDM System using Zero-Padding Technique

We introduce an adaptive channel equalization algorithm for orthogonal frequency division multiplexing (OFDM) employing high bandwidth-efficiency quadratic amplitude modulation (QAM) signaling. Our approach uses the guard band to yield a unique equalizer estimate through a least square fitting (LSF) criterion. To refine the equalizer estimation, a combination of a LSF and constant modulus algorithm (CMA) based equalizer is proposed. In order to minimize the error of the overall structure, a stochastic gradient algorithm is implemented. It is shown that the proposed scheme is superior and more robust in low signal to noise ratio (SNR) environments. Simulation results demonstrate that using the combination scheme improves adaptive channel equalization by increasing convergence rate and decreasing the steady-state mean square error.