Chaos-based Asynchronous DS-CDMA systems and enhanced rake receivers: measuring the improvements

Results of recent theoretical investigations highlighted that the use of chaos in direct-sequence code-division multiple access (DS-CDMA) systems may lead to nonnegligible improvements in communication quality for several scenarios. We here briefly review the main steps in this derivation and report the experimental verifications of the corresponding theoretical prediction. With this, we confirm that chaos-based spreading sequences outperform classical pseudo-random sequences in at least two important cases. Over nonselective channels, the ability of chaos-based spreading of minimizing multiple-access interference leads to a measured 60% improvement in [P.sub.err] with respect to classical spreading. Over selective channels, the possibility of jointly optimizing chaos-based spreading and rake receiver profiles leads to improvements of up to 38% in [P.sub.err] with respect to systems with either conventional spreading or conventional rake policies. Index Terms--Chaos, code-division multiple access, communication-system performance, rake receiver.