Narrowband Interference Suppression in a Spreading WFRFT System and Optimal Order Selection

A spreading system based on weighted fractional Fourier transform (WFRFT) is proposed over the channel with additive white Gaussian noise (AWGN) and narrowband interference (NBI). The cross-correlation coefficient between pseudo-noise (PN) sequence and NBI (CPI) and the proposed system's bit error rate (BER) are deduced. We proved that the optimal WFRFT order can be obtained to achieve the best BER performance through minimization of CPI. Numerical results show that the optimal WFRFT order can reduce the adverse effect caused by NBI in different distribution states.