On the Performance of OFDM Systems in Time Varying Channels with Channel Estimation Error

In this paper, we analyze the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems in time varying channels with channel estimation error. The conventional approach to obtain an analytical expression for the average error probability (bit or symbol) relies on finding the joint probability density function (PDF) of the channel and the channel estimate, and then, average the conditional error probability over the joint PDF. Usually, averaging the conditional error probability requires solving a three-fold integral. We will first give a simple proof to the asymptotic Gaussianity of the Intercarrier Interference (ICI), then we show that by expressing the channel in terms of the channel estimate, the problem of obtaining the average error probability is greatly reduced, and simplified to solving a single integral. The derived expressions are general, and may be used to analyze the performance of a variety of channel estimation schemes for OFDM systems in static and time varying channels.