Multi user chaotic communication systems using orthogonal chaotic vectors

Abstract

Due to quasi orthogonal nature of chaotic spreading sequences, the co-channel interference will be introduced and increases with the increase in number of users and limits the number of simultaneous users transmitting information. In this dissertation the application of orthogonal chaotic vector (OCV) for spreading information bits is presented. The bit error rate of the multi user chaotic communication system is analysed through simulation and analytical expressions. Two main types of communication scenarios are considered, multi user chaotic communication system with coherent receiver and training assisted non coherent multi user chaotic communication system with adaptive receiver. The first case deals with ideal scenario where it is assumed that exact replica of chaotic vector used to spread data is available at the receiver and the information is extracted without synchronisation error. Thus lacks practical realisation but, the results obtained will provide a lower bound for comparison with other practical counter parts. The second scenario deals with more practical approach where a reference chaotic sequence is also transmitted by modulating with training bits so that the chaotic vector required for correlation can be recovered at the receiver.