ISSN : 1796-2021
Volume : 3    Issue : 4    Date : September 2008

An OFDM Symbol Design for Reduced Complexity MMSE Channel Estimation
Carlos Ribeiro and Atílio Gameiro
Page(s): 26-33
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In this paper we revisit the minimum mean square error (MMSE) pilot-aided channel estimation for
broadband orthogonal frequency division multiplexing (OFDM) systems. The careful design of
OFDM symbol leads to the proposal of a simplified time-domain (TD) MMSE estimator. By exploring
the Fourier properties of the symbol, the investigated method eliminates the need to use direct or
inverse discrete Fourier transforms (DFT/IDFT) before the channel estimation, by using the TD
received symbol samples as the input to the MMSE filter. Moreover, performing the estimation in TD
(where the channel impulse response (CIR) energy is mainly limit to a small set of samples),
makes way to a simple, nonetheless efficient estimation of the filter parameters. The performance
of the channel estimation scheme, using the estimated parameters, presents a tolerable
degradation when compared with the ideal situation (a-priori knowledge of the channel correlation
and noise variance), while exhibiting a reduced computational load. The feasibility of the
investigated method is substantiated by system simulation using indoor and outdoor wireless
channel models.

Index Terms
OFDM, pilot-aided channel estimation, timedomain processing.