Doubly-Selective Channel Estimation for Packet OFDM Systems with Virtual Subcarriers

Channel estimation based on two-dimensional discrete- time Fourier transform interpolation (2D-DFTI) is suitable for orthogonal frequency division multiplexing (OFDM) systems because of its robustness to doubly-selective fading channels and high computational efficiency. However, its performance will degrade significantly for packet OFDM systems with virtual subcarriers due to the Gibbs phenomenon in both frequency- domain and time-domain. We have already proposed the frequency- domain enhanced DFT interpolation (FD-EDFTI) to effectively suppress the Gibbs phenomenon in frequency-domain, while in this paper the time-domain enhanced DFT interpolation (TD-EDFTI) is further proposed to mitigate the Gibbs phenomenon in time-domain. Therefore, doubly-selective channel estimation based on 2D-EDFTI can be easily implemented for packet OFDM systems with virtual subcarriers by concatenating FD-EDFTI with TD-EDFTI to efficiently suppress the Gibbs phenomenon in both frequency- domain and time-domain, while keeping good robustness and high computational efficiency.