Enabling chaotic waveform diversity

Utilizing chaotic waveform diversity is one method for the generation of signals which appear random, in terms of its first-order and second-order statistics, thereby appearing indistinguishable from background noise. This technology is clearly advantageous for secure communications through covert waveform synthesis. In situations where digital chaotic encoding is undertaken, the evaluation of the performance of the direct synthesis of such signals generally gives rise to comparatively high energy-per-bit-to-noise-power-spectral-density (E_b/N_o) measurements for reliable communications. Analysis has indicated that increasing the complexity of the signal composition results in degradation in error-rate performance; this effect being related to the increase in the signal dimension necessary for assuring increased waveform covertness simultaneously rendering a detrimental cross-noise effect to signal recovery. Methods for alleviating this paradox include the utilizing of spread spectrum techniques, both temporal and spectral, as well as the augmentation of error control coding (ECC) techniques. Furthermore, previous work has developed receiver architectures which improve information recovery performance. A ready technology for enabling chaotic waveform diversity is through utilizing software defined radio (SDR) techniques, a technology that promotes rapid and agile waveform diversity. This paper discusses various attributes of waveform diversity and design (WDD) with particular attention to digital chaotic encoding for secure and covert communications, performance assessment and enhancement and the benefits of SDR for enabling chaotic waveform diversity.