Channel Estimation Based Adaptive Interpolation for WRAN System

A channel estimation algorithm based on adaptive complex coefficient interpolation is proposed for improving the ability to combat multipath delay of wireless regional area network (WRAN) system greatly. WRAN is the first broadband access standard to improve the spectrum efficiency by making use of cognitive radio technology. Orthogonal frequency division multiplexing (OFDM) is used in the downlink of WRAN system and channel estimation is very important for the coherent demodulation of OFDM system. However, traditional channel frequency response estimation algorithms adopted by real coefficients interpolation of OFDM systems is sensitive to long delay channel. According to transform domain response of real coefficient finite impulse response (FIR) interpolation, a complex coefficient interpolation algorithm is derived in this paper. In order to apply for short delay channel simultaneously, a low-complexity algorithm which matching channel maximum multipath delay adaptively is proposed. Then the estimation performance is investigated and simulated. Experimental results verified the theoretical analysis and the validity of the proposed scheme.