DFT-Based Channel Estimation in Comb-Type Pilot-Aided OFDM Systems with Virtual Carriers

In orthogonal frequency division multiplexing (OFDM) systems, conventional channel estimation techniques using comb- type preambles and interpolation between pilot subcarriers give relatively large mean square errors (MSEs) at the edge sub- carriers. Furthermore, the spacing between pilot subcarriers in the frequency domain has to be close enough according to sampling theorem. To solve these problems, an iterative discrete Fourier transform (DFT)-based channel estimation with comb-type pilot-aided is proposed in this paper. The complete channel frequency responses (CFRs) including virtual subcarrier positions are estimated by recursive method with the small size of DFT/Inverse DFT. Simulation results show that the proposed algorithm outperforms the conventional linear minimum mean square error(LMMSE) algorithm using comb-type preamble.