On the Use of Virtual Pilots with Decision Directed Method in OFDM Based Cognitive Radio Channel Estimation Using 2x1-D Wiener Filter

In this paper we propose the novel concept of virtual pilots to aid the channel estimation In OFDM based Cognitive Radio system with the optimum Hexagonal pilot pattern. The virtual pilots are derived from the simple linear Interpolation and extrapolation combined with decision directed method in reducing the effect of noise to the initial channel estimates. The results have shown that the use of virtual pilots has almost reached the mean square error performance of two times oversampling pilot allocation without adding additional pilots.