Chaos-based digital communication systems with low data-rate wireless applications

Abstract

This chapter presents a study on the modeling and performance evaluation of chaos-based coherent and incoherent systems, i.e., chaotic direct-sequence code-division multiple-access (CDS-CDMA) and differential chaos-shift keying (DCSK), for low-data-rate applications in wireless communications. This study is motivated by the design of a secure physical layer for wireless-based applications with low data rate and in small transmission areas. A wireless channel affected by noise, fading, multipath, and delay-spread for low-data-rate transmission of chaotically spreading signals is described and mathematically modeled. Discrete-time models for the transmitter and receiver of CDS-CDMA and DCSK systems under the impact of the wireless channel are developed. Bit error rate (BER) performance of the systems is estimated by means of both theoretical derivation and discrete integration. Simulated performances are shown and compared with the corresponding estimated ones, where the effects of the ratio Eb/ N0, spreading factor, number of users, sample rate, and the number of transmission paths on the BER are fully evaluated. The obtained results showed that the low-rate chaos-based systems can exploit the multipath nature of wireless channels in order to improve their BER performances. This feature indicates that chaos-based communication systems are a promising and robust solution for enhancing physical layer security in low-rate wireless personal area networks (LR-WPANs).