A New Ofdm-Cr Channel Estimation Algorithm Used In Fast Time-Varying Fading Channels Based On Fractal Theory

Cognitive Radio (CR) can improve the spectrum utilization for its efficient use of idle spectrum for data transmission. In CR systems based on Orthogonal Frequency Division Multiplexing (OFDM), the effective receiving performance requires the ideal channel estimation. This paper presents a new channel estimation algorithm that considers the fractal characteristics of multipath fading signals in OFDM-CR systems, which is especially effective in fast time-varying fading channels. Observing that fractal theory can reveal the inherent change law of channel fading, we introduce an algorithm to extract the multifractal features of OFDM-CR channels. Together with the Fractional Brownian Motion (FBM) model, a new channel estimation scheme using fractal interpolation is presented. Numerical simulations show that the new channel estimation algorithm can reduce the Bit Error Rate (BER) notably when the channels change dramatically.