Interference excision in spread spectrum communications using adaptive biorthogonal local discrete cosine transform

A novel spread spectrum communication receiver employing adaptive biorthogonal local discrete cosine transform (BLDCT) is designed for stationary and nonstationary interference excision. The adaptive BLDCT-based excision algorithm uses a redundant library of biorthogonal local discrete cosine bases and an efficient concave cost function to match the transform basis to the interfering signal. The main advantage of the algorithm over conventional transform domain excision algorithms is that the basis functions are not fixed but can be adapted to the time-frequency structure of the interfering signal. It is well suited to transform domain compression and suppression of a variety of interference types. Compared with discrete wavelet transform (DWT) that provides logarithmic division of the frequency bands, the adaptive BLDCT can provide more flexible frequency resolution. Thus it is more insensitive to the jammer frequency. Simulation experiments demonstrate the improved bit error rate (BER) performance and the increased robustness of our receiver. Copyright © 2004 AEI.