Interference Suppression in DS-SS Systems with Modified Discrete Fourier Transform

The performance of traditional interference excision method based on the discrete Fourier transform (DFT) in direct sequence spread spectrum (DS-SS) system varies significantly with the frequency of the interference due to the grid biases of the DFT operation. This paper presents a new excision method by using modified DFT (MDFT) with an extra parameter to enhance the BER performance for a large range of interference to signal ratio (ISR). With the tradeoff between the energy of the remaining interference and the distortion of the desired signal, simulation results are presented to show that removing the peak of the components in the MDFT domain yields the best performance