A New Robust Interference Reduction Scheme for Low Complexity Direct-Sequence Spread-Spectrum Receivers: Optimization

We present a self-adaptive algorithm for a new robust direct-sequence spread-spectrum system with integrated interference reduction capabilities to reduce narrowband- and broadband-interference regardless of their composition. Our reliable chip accumulation detector combines a comparatively low processing gain direct-sequence spread-spectrum system with an efficient interference reduction technique based on a simple adaptive nonlinearity employed prior to spread-spectrum demodulation. The information required for adjusting the adaptive nonlinearity to track the optimum state for efficient interference reduction is solely extracted from the received signal, primarily by exploiting level-crossing information. The resulting algorithm is fast, avoids loop structures, has no stability problems, and is easy and cheap to implement in hardware. The results of our Monte-Carlo simulations reveal that the proposed receiver always achieves the minimum symbol-error-probability, even under interference conditions that vary in the range of 40 dB.