Time-varying channel estimation for OFDM with extended observation window

Orthogonal Frequency-Division Multiplexing (OFDM) systems operating in high mobility environments experience time-varying channel, which leads to serious inter-carrier-interferences. Basis Expansion Model (BEM) is a widely used technique to estimate the time-varying channel, but can only capture the time-varying characteristics within each single OFDM block one by one in traditional algorithms. A method to extend the observation window of BEM based algorithms to the range of multiple OFDM blocks is established and adapted to pilot-assisted OFDM systems, where pilot signals in multiple OFDM blocks are converted into time-domain and connected together. As a result, the time-varying channel can be estimated more accurately, with comparable complexity as those of traditional algorithms.