Efficient and flexible chaotic communication waveform family

Harris has developed, implemented, and characterized a highly efficient and flexible digitally generated family of chaotic waveforms for high information density, anti-jam, LPI/LPD/LPE, and “self-encrypted” application spaces. This paper introduces an efficient mechanism to generate a chaotic signal digitally, while tailoring waveform characteristics for maximum performance in various application spaces, overcoming known limitations in DSSS communications. The paper discusses the desirable characteristics of the various chaotic waveform variants as well as the advantages these operational digital chaotic communication systems provide over traditional but yet to be practically realized analog based systems. The architecture of a hardware prototype implementation is presented along with key measured performance parameters. Harris bases our family of chaotic waveforms on an efficient number theoretic digital chaotic implementation that enables extreme epoch lengths without apparent chaotic attractors in a small and power efficient hardware or software footprint. The chaotic characteristics can be customized for the target application space. For example, the chaos can be shaped into a quadrature Gaussian distribution for maximum information density and maximum LPI/LPD/LPE effectiveness, it can have a constant amplitude envelope and uniformly distributed random phase for AJ applications, it can be simply divided into code division multiplexing or orthogonal waveform division for multiple access communications, or it can be easily adapted to hybrid distributions with time-varying characteristics to provide environment aware `cognitive' links. Because of the absence of apparent attractors and code epoch times measured in googol-years (10
¹⁰⁰
years), the waveforms are extremely secure. We describe chaotic spread-spectrum waveforms in this paper, although chaotic techniques can be extended to other systems. As such, chaotic state synchronization becomes carrier frequency, phase, and timing synchronization of a digital communication system that are well understood and straight forward to implement. Adapting basic techniques used in direct sequence spread spectrum communications to the chaotic waveform enables a robust synchronization between independent chaotic circuits and their resulting waveforms. The paper briefly introduces the desirable features of a chaotic communication system and contrasts the advantages of digital and analog chaos based communication systems. We present the digital chaotic sequence generator architecture, followed by a prototype coherent chaotic communication system implementation, including characteristic measurements. Finally, we correlate the specific advantages of the different chaotic waveforms to a range of potential applications.