Turbo equalization based on a new Kalman filter for OFDM over doubly-selective channels

In OFDM systems, multi-path spread and Doppler frequency spread result in the channel fading to be time-and frequency-selective (doubly selective). In such cases, the channel fast variations destroy the orthogonality among sub-carriers, resulting in inter-carrier interference (ICI) which degrades the performance. Aiming at time-varying characteristic of doubly-selective channels, we propose a channel estimation algorithm by a new Kalman filter, and apply it to the oversampled complex exponential basis expansion model (OCE-BEM), changing the variable channel parameters in the period of one OFDM symbol into invariable ones. Meanwhile, we combine this new Kalman filter with the low complexity LMMSE Turbo equalizer based on ICI mitigation, so we neednpsilat many pilot symbols in practice, still can ensure the algorithm performance and reduce the time-delay and complexity of this algorithm.