Iterative Channel Estimation for SISO and MIMO-OFDM Systems in Time-Varying Channels

Abstract-This paper proposes a simple and efficient algorithm using polynomial interpolation for SISO and MIMO-OFDM systems in a fast time-varying channel. The time averages of the multipath complex gains, over the effective duration of each OFDM symbol, are estimated using LS criterion. After that, the time variation of the channel within several OFDM symbols are obtained by interpolating the time average values using polynomial interpolation. Specifically, we propose and evaluate the performance of channel estimation using third-degree polynomial interpolation with an adaptive pilot scheme in order to optimally use pilot tones over time varying channels. The ICI can be cancelled by using partial successive interference cancellation (PSIC) in data symbol detection instead of basic SIC method. Keywords-Channel estimation, OFDM, MIMO, Mobile multipath channel. I. INTRODUCTION OFDM (Orthogonal Frequency Division Multiplexing) has been widely applied in wireless communication systems due to its high data rate transmission and its robustness to multipath channel delay In OFDM systems, channel estimation is usually performed by sending training pilot symbols on subcarriers known at the receiver and the quality of the estimation depends on the pilot arrangement. Since the channel's response is a slow varying process, the pilot symbols essentially sample this process and therefore need to have a density that is high enough to reconstruct the channel's response at the receiver side • The amount of pilot symbols to be transmitted; • The complexity of the estimator. The MMSE estimators have good performance but high complexity. The LS estimator has low complexity, but its performance is not as good as that of the MMSE estimators In the present paper, we present an iterative algorithm for channel estimation with inter-sub-carrierinterference (ICI) cancellation in MIMO OFDM systems using polynomial modeling (P-BEM) and an adaptive pilot pattern. For a Jakes' spectrum Rayleigh gain, it has been shown in The proposed algorithm, with less number of pilot tones and with low computational complexity, gives a good performance over the conventional methods. This proposed algorithm can in fact be considered as an extension of an algorithm for time-variant channels My Abdelkader Youssefi et al. / International Journal of Engineering and Technology (IJET

Error performance of OFDM signaling over doubly-selective Rayleigh fading channels

In this letter a simple method for the evaluation of the error rate performance of OFDM signals transmitted over doubly-selective fading channels is described. The accuracy of the proposed technique is exemplified by simulation results