Spreading Sequence And Sequence Pairs Design And Application

The spreading sequence designs are one of the key projects of the spreading spectrum communication systems.The auto-and cross-correlation properties of the spreading sequences employed play an important role in CDMA,and therefore directly influence the performance of the systems.This thesis surrounds the theory of the spreading sequence and their pertinence, research on low correlation zone spreading sequence designs with interleaved configuration and zero correlation zone spreading sequence pairs designs and so on .Base on this theory , we gained a class of low correlation zone spreading sequence and zero correlation zone spreading sequence pairs.This thesis aims to construct a low correlation zone sequence set with the method of algorithm of prime based on the theory of optimal periodic autocorrelation sequence and orthogonal spreading sequence. Low correlation zone sequence acquired with this method, therefore, meets the requirement of a large number of users on the simultaneous use of quasi-synchronous CDMA with the advantages of enjoying more numbers of sequences. Moreover, researches have been done on Pre-rake combining technology, low correlation zone sequence acquired from the above design have been applied to it as well. Analyse the simulated result indicated that by the low correlation zone sequence based Pre-rake combining ,we can get the higher interference and noise ratio(SINR), result better bit error rate(BER) and bigger capacity. At the same time, this thesis present a new method to construct a class of zero correlation zone sequence pair sets. By adopting the theory of sequence pairs and based on interleaved technique and the shift sequence of a class of optimal ZCZ sequence sets, ,ZCZ sequence pairs sets are constructed with good autocorrelation function and cross-correlation function which not only generate different ZCZ, but also the sequences obtained are cyclically distinct. The result indicates that its performance is perfect, it can be used as the spreading codes in the quasi-synchronous CDMA systems.