INVESTIGATIONS ON THE PERFORMANCE ENHANCEMENT OF SELF ENCODED SPREAD SPECTRUM IN WIRELESS COMMUNICATION

Abstract

Spread spectrum systems are employed for the secure transmission of digital information which is achieved through spreading the signal in frequency domain. Pseudo-Noise (PN) sequences are conventionally used for this spectrum spreading and de-spreading process. However, the PN sequences are not truly random in nature and follow a deterministic pattern. Though the suitability of random sequences have been tested for the same purpose, feasible implementation of such systems is impossible as de-spreading at the receiver requires knowledge of the exact sequences that have been generated in the transmitter for signal spreading. The Self-Encoded Spread Spectrum (SESS) is a novel spread spectrum communication system developed to enhance the randomness and security of data transmissions through an inventive self-encoding principle. The self-spreading sequence is generated from the information to be transmitted and it eliminates the usage of PN sequences. The registers of SESS system used for generating the self-spreading sequence should be preloaded with a known sequence. As this initial sequence, chaotic sequences are used and its characteristics including correlation properties are evaluated. This paper presents the performance evaluation of SESS with chaotic initial sequence in different channel conditions such as Additive White Gaussian Noise (AWGN) channel and Rayleigh fading channel. Also the effect of jamming in SESS is studied to ensure its applicability as a secure communication system.