The Simulation Study Of Self-encoded Spread Spectrum System

Due to the ramarkable advantages in such areas as anti-jamming and low interception,the Spread Spectrum Communication have been widely used with the fast development of integrated circuit and large-scale usage of microprocessor applications.But a certain shortage of DSSS system lies in using the pseudo-noise(PN) sequence as its spreading sequence,as a result,information may be intercepted by eavesdroppers for its periodicity of PN sequence.Therefore,the security of communication will have some threat.In order to achieve a lower interception rate and hign anti-jamming,Lim Nguyen fistly proposed the concept of Self-encoded spread spectrum (SESS)communication in1999.Bing different from traditional spread spectrum,the source coding is mainly used to generate the spread sequence.On condition that the source coding gets good condense and encoded,the spreading spreading spectrum produced by it could be absolutely equipped with randomness,so that it enhances the randomness of the spread spectrum communication system,the dynamic variability and high anti-jamming.The paper firstly introduces the theory of SESS,and analyzes the distribution and statistic quality of the self-encoded spread sequence.Then it focuses on the research in the BER of DSSS,especially,analyzing theoretically and testing simlation of SEDS system in additive white Gaussian(AWGN) and non-related Rayleign fading channel,and comparing with traditional direct spreading.Next, the article discuses the influence of the SEDS system by self-interruption.Then,it reasearches the BER of self-encoded Spread Spectrum Multi-Acess(SEMA) system. Lastly,the article proposes some methods to improve the quality of SEDS system:(1)It proposes two methods to improve Self-encoded sequence:one is combining with PN code so as to improve the BER in the low SNR;the other is increasing redundancy registers,so as to strengthen anti-jamming at the same time of increasing randomness of spread sequence.(2)To increase anti-declining of SEDS system and decline the influence of the self-interruption on the condition of low SNR,the anthor introduces Diversity Technology.Finally,the article analyzes and compares the quality of system which id produced by three Diversity Technology individually (MGC,EGC and SC).