CHAOTIC SPREADING CODES AND THEIR GENERATION

摘要

Generation of a set of spreading codes starts with determining first and second chaotic pseudo-random noise codes having delta-peak-like autocorrelation functions and a low cross-correlation function. Further codes are obtained by the steps: (a) generating a further pseudo-random noise code by computing D<SUB>k </SUB>= F(C<SUB>1</SUB>) + T<SUP>k</SUP>C<SUB>2</SUB> +F(C<SUB>2</SUB>), where k represents a positive integral index, D<SUB>k</SUB> the generated pseudo-random noise code, C<SUB>1</SUB> the first code, C<SUB>2</SUB> the second code, F a binary function based on basic binary operations and T<SUP>k</SUP> the operator cyclically shifting a code by k chip positions; (b) adding code D<SUB>k</SUB> to the set of already determined pseudo-random noise codes if it has a delta-peak-like autocorrelation and low cross-correlation functions with the pseudo-random noise codes already determined; (c) discarding code D<SUB>k</SUB> if the conditions of step (b) are not satisfied; (d) modifying index k and repeating steps (a)-(d) until the cardinal number of the set of determined pseudo-random noise codes reaches the cardinal number of the set of spreading codes to be generated.