Second-order channel parameter estimation assisted cancellation of channel variation-induced inter-subcarrier interference in OFDM systems

摘要

OFDM transmission is known to be sensitive against carrier frequency offsets, as well as against the channel impulse response (CIR) variations incurred during an OFDM symbol period. Both of these phenomena lead to inter-subcarrier interference (ICI). Here we will concentrate on the latter phenomenon. ICI can be considered as an additional noise contribution, which linearly depends on the signal power and thus it potentially limits the achievable BER at relatively high SNRs. In this contribution we propose a second-order time-domain CIR tap variation estimator, which relies on both the received signal as well as on tentative symbol decisions. Our simulation results obtained in the context of a system employing decision-directed channel-prediction demonstrate that with the aid of the proposed algorithm, ICI cancellation can be performed even in high Doppler frequency channel scenarios. This is achieved without inserting additional time-domain pilot symbols.