Reliability-Based Precancellation of Inter-Carrier Interference for Highly Mobile OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) systems in fast time-varying channels suffer from inter-carrier interference (ICI), which necessitates the use of ICI mitigating equalizers. The performance of the equalizers strongly depends on the channel estimation (CE). Estimating the channel matrix in the frequency domain using pilot estimates can only provide limited performance, because pilots are also corrupted by ICI. We propose two approaches for reliability-based ICI precancellation at the receiver to improve CE. Firstly, a log-likelihood ratio window is used to optimize the interpolation points for CE. Secondly, a post-processor is employed to improve the estimates of the pilots´ neighbours. The low-complexity minimum mean squared error decision feedback frequency equalizer, which exploits the banded structure of the channel matrix, showed increased performance gains after ICI precancellation.