Coded Direct-sequence Spread Spectrum Mechanism To Improve The Model

Modern electronic counterwork technic could exactly estimate the carrier frequency , signal period, even the pseudo-random (PN) sequence itself of direct sequence spread spectrum (DSSS). It is urgency to investigate a new DSSS to achieve lower Low Probability of Detection(LPD) and higher Anti-Jamming.At 1999, Lim Nguyen first brought forward a novel self-encoded spread spectrum(SESS) system, which spread spectrum sequence is full builded by the source data. It needs to better understand and study on some problems,such as the best codes of its spread sequence, communication synchronization and so on.In this article, in addition to summarize some results, renew some formulas, especially simulate and analyze the self-interference(SI) unusual existing in SESS, we sum up the mostly performance improvement technology, namely error-correct code,transmitter-based precoding and source randomness. On this way we demonstrate SESS's feasibility and point out it is the SI which is main reason leading to high communicate performance limit. Aiming at spread sequence isn't strict balance in the basic SEDS system, we set up three improved models,which can make the sequence balance ,at the same time their BER performances is different. We consider,via analyzing the basic model in theory, that it should adopt mod. External model when there is high SNR, otherwise it should adopt SEDS+ECC mode.which is verified in latter simulation. Additional two improved models,namly transmitter precoding and source randomness are also introduced.Comparing some SESS systems which has different co-correlation on single user and multi-user conditions, we indicate the efficient means is to pick out the proved good correction sequences,such as Gold sequence, to amend correlation. To reduce sequences collision in multi-user condition, The corresponding value of function G should have equal distributing and SESS sequence family should as large as it can.