Interference excision in DSSS communication system using time-frequency adaptive block transform

Abstract

An adaptive time-frequency interference exciser based on block transform packets for a DSSS communication system is presented. In this technique, a succession of time-frequency distributions for each frame of data is calculated. From this distribution, the location and shape of the most energetic time-frequency tile is found along with its associated basis function. The projection of the signal onto this basis function is then subtracted from the original signal to form a residual. This process is repeated on the residual signal until the resulting time-frequency spectrum is flat. This scheme substantially reduces the interference power with minimum possible distortion of the desired spread spectrum signal. Our simulations demonstrate that the proposed adaptive time-frequency excision method dramatically outperforms the existing transform domain based excisers for narrowband and time-localized jamming signals.