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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...
This paper is the extension of the first paper (Rashad et al., 2007) that described the modification of rectangular pilot pattern applied in OFDM-based cognitive radio system. In this paper, a new concept for pilot symbols arrangement in OFDM transmission system is introduced. The new idea is the virtual pilot symbols concept which is based on the interpolation of the received pilot symbols. Further...
Nowadays research in the area of Cognitive Radio has grown tremendously. In the application of spectrum pooling in OFDM-based Cognitive Radio system there will be subcarriers that are deactivated due to the access of Licensed Users. The unloaded subcarriers that are caused by Licensed Users access create problems in performing channel estimation. The unloaded subcarriers restrict putting the pilot...
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