Low Complexity Channel Estimation in Fast Time-Varying Channels for OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is widely adopted in broadband wireless communication systems. However, its performance suffers from the inter-carrier interference (ICI) induced by fast time-varying channel resulting from high mobile speed. Reliable coherent OFDM systems require an accurate channel estimation. Our aim, in this paper, is to propose the channel estimation that is low computational complexity and robust to the fast time-varying channels. The proposed channel estimation is based on the pilot-assisted polynomial interpolation in a multi-symbol configuration. In this method, the time variations of each channel path corresponding to the successive OFDM symbols, regarding as an observation window, are interpolated by arbitrary polynomial order functions. Simulation results show that the interpolation performing over a window profits low pilot overheads. It also shows the offline mode reduces the computational complexity by as high as 99.9% whereas achieving good performance. This method, with low complexity and low pilot overhead, can provide high performance in the fast time-varying channels.