Particle Filtering for Tracking Time-Varying Dispersion Channels in OFDM Systems

Orthogonal frequency-division multiplexing (OFDM) is robust against frequency selective fading due to the increase of the symbol duration. However, for mobile applications, channel time-variations in one OFDM symbol introduce inter-carrier interference (ICI) which degrades the performance. This becomes more severe as mobile speed, carrier frequency or OFDM symbol duration increases. Therefore, the performance of coherent OFDM systems greatly depends on the ability to accurately estimate the effective dynamic channel. In this paper, we analyze the ICI in OFDM systems when it operates over time-varying dispersion channels, and build an auto-regressive (AR) model of the channel dynamics based on the Jakes´ model. A pilot symbol aided particle filter method is presented for the estimation and tracking of the channel. Finally, simulation result shows how the proposed method would improve the performance of OFDM systems