Chaotic Communications, their applications and advantages over traditional methods of communication

The discovery of randomness in apparently predictable physical systems have evolved into a new science, the science of chaos. Chaotic systems are unstable and aperiodic, making them naturally harder to identify and to predict. Recently, many researchers have been looking at ways to utilize the characteristics of chaos in communication systems and have actually achieved quite remarkable results. This field of communication is called chaotic communication. Chaotic communication signals are spread spectrum signals, which utilize large bandwidth and have low power spectrum density. In traditional communication systems, the analogue sample functions sent through the channel are weight sums of sinusoid waveforms and are linear. However, in chaotic communication systems, the samples are segments of chaotic waveforms and are nonlinear. This nonlinear, unstable and aperiodic characteristic of chaotic communication has numerous features that make it attractive for communication use. It has wideband characteristic, it is resistant against multi-path fading and it offers a cheaper solution to traditional spread spectrum systems. In chaotic communications, the digital information to be transmitted is placed directly onto a wide-band chaotic signal. This paper provides an overview of chaotic communication, chaotic modulation schemes such as: chaos shift keying (CSK), differential chaos shift keying (DSK), additive chaos modulation (ACM) and multiplicative chaos modulation (MCM). Synchronized chaotic systems and direct chaotic communication are also described in this paper.