Serial equalization structure for channel compensation in OFDM systems

Abstract

By the advent of equalizers their major focus was to estimate the Channel Impulse Response (CIR). Finding such a transform function, detection of the transmitted data using the inversed CIR is the next step. To eliminate the first step in this paper, we implemented channel equalizers serially in the system. Unlike conventional methods, the proposed scheme estimates Inversed channel Impulse Response directly using adaptive algorithms. Frequency domain channel estimators are common and easy to implement in OFDM based system, but comparing to serial structure presented in this paper they are slow and inaccurate. Also for every one tap equalizer implemented in frequency domain we need one division operator for each FFT point while in proposed structure the filter length is fixed and operates on every data Frame. In this paper for an OFDM based system two channel estimation algorithms (RLS and NLMS) have been implemented using the proposed structure and the promising results have been presented. Moreover, by reducing computational complexity the proposed method also outperforms conventional schemes.