A Study on Equalization of OFDM Signal using Scattered Pilot Symbols

Abstract

This paper describes a new equalizer for Orthogonal Frequency Division Multiplexing (OFDM) using scattered pilot symbols. The channel transfer function is modeled as a combination of several propagation paths whose complex attenuation factors and delay times are estimated so as to minimize the differences between the received pilot symbols and the pilot symbols generated by this model. The received data symbols are equalized by using this model. Computer simulations are used to compare the bit error rate characteristics of the new equalizer with those of the conventional equalizer that esitimates channel transfer functions by interpolation. Under severe channel conditions such as fading channels, the new equalizer gives better bit error rate characteristics. When the carrier-to-noise ratio is low, the convensional method is a little better. This paper also describes a modification of the new equalizer which improves the bit error rate characteristics without much increasing number of calculations.