Structure And Performance Analysis Of Several New Spread Spectrum Codes

With picking up modern information age’s speed, the effect of information security become more and more important, and we have increasingly high demand for information transmission.Spread spectrum communication system has plenty of advantages such as good security, the capability of being intercepted and captured, anti-jamming ability, and code division multiple access (CDMA) and so on. Since the above advantages, it has been far and wide used in civil communication and military communication. Direct sequence spread spectrum (DS-SS) system’s technology is the most mature and its apply is the most widely in spread spectrum communication system. The range of codes interference and the strength of multiple-access interference depend on its spreading sequences’ properties in DS-SS system, which lead to system performance is directly effected. Therefore, the inves-tigation of codes’ properties and the designing scheme of spread code with good properties are the core technologies in direct sequence spread spectrum system. Meanwhile, it be-come key research contents in this text.In this paper, we study the development of spread spectrum communication theory, the basic knowledge and relevant theory of spread spectrum communication system Spreading sequences are classified and discussed by different view, and ternary spreading codes, self-encoded spread spectrum communication system, and the designed method of improving sequences with chaotic mapping ternary. In this work, the main research work includes several aspects as below:First of all, spread spectrum technology is introduced briefly, and then we classified spreading codes by sequence generator, which is main measure to study relative merits of different spreading codes. We summarize spreading codes’ excellent characters with this method, so that make preparations to propose new spreading codes. Spreading codes per-form well in like autocorrelation, cross-correlation, balance, complexity, chaos and other mathematics statistical features, and its presentation is concise and to the point in this pa-per.Secondly, ternary random number code is introduced briefly, which is constituted by the initial value and background which is users’ inputted and selected information, and al-gorithm which is the discrete trajectory transform. The code with novel constitution through homeomorphism uniform mapping or orthogonal transformation to obtain the ho-meomorphism ternary spreading code with good cross-correlation or orthogonal ternary spreading code with high random. After that, we test and verify their correlation, balance, Lyapunov exponent and bit error rate (BER) in DS-SS. The results show that ternary spreading codes’ performance is excellent, and its BER is low, especially, orthogonal ter-nary spreading code is lowest. In the same time, they can replace PN code as spreading codes of spread spectrum communication system.Thirdly, this paper analyses the self-encoded spread spectrum (SESS) system, and its spreading code is obtained from information source. The method of chaos mapping or two-dimensional hyperchaotic discrete combine with SESS and phase space trajectory iter-ation-feedback improve SESS system are presented, and chaotic auto-regressive self-encoded spreading code, hyperchaotic auto-regressive self-encoded spreading code and phase space auto-regressive self-encoded spreading code are obtained base on au-to-regressive self-encoded spread spectrum (AR-SESS), then through MATLAB to test Iheir property and BER.Fourthly, the new spreading codes in this paper and traditional spreading codes’ BER is tested under additive white Gaussian noise (AWGN) channel and Rayleigh fading chan-nel in multiuser communication system. At same time, it is proving that the huge difference of various kinds spreading codes in diverse spreading gain, and the BERof communicatbn system become lower with spreading gain become greater.The paper’s spreading codes perform well in complexity and randomness, therefore, they can improve the system’s security and anti-intercept ability to transmit information. If error code rate of information transmission system is main way of spreading code quality, the phase space auto-regressive self-encoded spreading code is the most optimal spreading code in the paper, and then hyperchaotic auto-regressive self-encoded spreading code, cha-otic auto-regressive self-encoded spreading code are on its heels, orthogonal ternary spreading code, finally, homeomorphism ternary spreading code is relatively poor.