Chaotic spreading sequences were previously proposed for use in direct-sequence spread-spectrum (DSSS) communications systems, and it was suggested that the nonbinary nature of these sequences would result in an improvement in the low probability of intercept (LPI) performance of the signal. In this letter, we derive the structure of the optimum intercept receivers for chaotic DSSS signals in a statistical framework by exploiting the known probabilistic behavior of spreading sequences. A performance comparison between the optimal receivers and more practical suboptimum detectors—which overlook the multilevel nature of chaotic sequences—is also provided. The results imply that the use of chaotic spreading sequences would not help increase the covertness of DSSS signals.
['Sedighe Sedaghatnejad', 'Mahmoud Farhang']
Detectability of Chaotic Direct-Sequence Spread-Spectrum Signals