It is shown that a class of tailed shift chaotic maps can be designed with
substantial negative dependence, both linear and non-linear, and that exten
ded Perron-Frobenius theory gives their dependence structure. Using a simpl
ified chaos-based communication system, it is shown that chaotic spreading
sequences with low kurtosis and negative non-linear mean-centred quadratic
autocorrelations can improve bit-received accuracy. This quadratic form of
non-linear dependence Is investigated and shown to be statistically sensibl
e.