Comparative study of time-frequency analysis based interference suppression methods in DS-SS communications

Three methods for suppressing interference, whose frequency properties change over time, are presented. The methods take advantage of both time and frequency information of the received signal. Two algorithms are based on modifications of the Fourier transform (short-time Fourier transform (STFT) and fractional Fourier transform (FrFT)) and the third method is based on instantaneous frequency estimation. The performance of the algorithms in a direct sequence spread spectrum (DS-SS) communication system is evaluated through simulations and the most promising method is considered to be FrFT based exciser. A problem with FrFT is choosing the order of the transform.