Research On Coding Techniques Using In Self-Encoded Spread Spectrum System

With the development of the modern electronic counterwork techniques, the estimate of the carrier frequency, signal period, and even the pseudo-random (PN) sequence itself of direct sequence spread spectrum (DSSS) is possible. It is an urgency to investigate a new DSSS to achieve lower Low Probability of Detection (LPD) and higher Anti-Jamming performance.In 1999, Lim Nguyen first brought forward a novel self-encoded spread spectrum (SESS) system, in which spread spectrum sequence is fully built by the source data. It needs better understanding and studying on some problems, such as the principle of the SESS system, the best coding of the spread sequence, communication synchronization and so on.In this article, we introduce the basic principle of the self-encoded direct spread (SEDS) system, construct the model of the system, and analyze the main performances of the system, such as BER performance, self-interference, MAI performance and so on.Aiming at that spread sequence isn't strict balanceable in the basic SEDS system, we set up three improved models, which can make the sequence balanceable. At the same time their BER performances are different. By analyzing the basic model in the theory, we can come to the conclusion that the mod. External model can be used when high SNR, while the SEDS+ECC mode can be used when low SNR.By using the AR technique it becomes easier to implement the self-encoded spread spectrum system. And it improves the BER performance under the low SNR condition. Then the theory of the AR model and the random performance of the spread spectrum sequence, including co-correlation, balance are discussed.We build the baseband model of the AR self-encoded spread spectrum system both for a user and multi-user, and do a lot of simulation for the system. In addition, we discuss the performance deeply based on the simulation. It provides a good choice for the practical application of the SESS system.