Research On The Design Of Sequences With Low Or Zero Correlation Zone

In code division multiple access (CDMA) systems, multiple access transmissionactualizes by spreading sequences and the level of the interference is determined by thecorrelation of spreading sequence. Therefore, it is important to construct spreadingsequences with good correlation for the high-performance and the high-capacity of theCDMA system. In this thesis, we give a study on the design of sequence set with low orzero correlation zone (LCZ/ZCZ), periodic complementary sequence, sequence with idealautocorrelation, and LCZ/ZCZ array set.Firstly, the construction methods of shift distinct LCZ/ZCZ sequence sets areproposed. Constructions of shift sequence with length2and P are proposed, where P2and P|L, L is the length of LCZ/ZCZ. Then multiple shift distinct LCZ/ZCZ sequencesets are constructed by using interleaving technique. The upper bound of the LCZ/ZCZshift sequence sets is computed for the construction based on N2interleaving matrix.The sufficient condition under which the LCZ/ZCZ shift sequence sets are optimal ispresented for the construction based on N Pinterleaving matrix. Compared withprevious constructions, the two new constructions provide more spreading sequences toquasi-synchronous code-division multiple-access (QS-CDMA) systems.Secondly, the methods of constructing Gaussian integer sequence with goodautocorrelation are proposed. Balanced quaternary sequences with optimal autocorrelationvalue and perfect8-QAM/8-QAM+sequences, which are two classes of special Gaussianinteger sequences, are constructed. Then constructions of perfect Gaussian integersequences are presented. According to the parity of the multilevel perfect sequences overinteger, different mappings and combined methods are used for constructing perfectGaussian integer sequences. New Gaussian integer sequences are generated by theproposed construction and the number of the existing perfect Gaussian integer sequencesis extended.Thirdly, the construction methods of LCZ/ZCZ Gaussian integer sequences areproposed. Based on a binary sequence with two-level autocorrelation, multiple quaternaryLCZ sequence sets with the same parameters are constructed by using different mappings. The parameters of the resultant LCZ sequence sets can be flexibly chosen. The sequencesfrom one quaternary LCZ sequence set are all shift distinct and there is only one shiftequivalent sequence from different sets. Furthermore, two classes of optimal or almostoptimal Gaussian integer sequence with ZCZ are constructed based on perfect Gaussiansequence. In addition, different shift or mapping operations are applied to Gaussianinteger periodic complementary sequence sets and ZCZ Gaussian integer periodiccomplementary sequence sets, then two classes of Gaussian integer periodiccomplementary sequence with ZCZ are constructed.Finally, the construction methods of ZCZ array set are proposed. Based on perfectsequence, two classes of two dimensional ZCZ array sets are constructed. Both methodscan be used for constructing ZCZ array set over Gaussian integers. Moreover, the resultantarray sets are optimal or almost optimal and the parameters of the array sets can beflexibly chosen so as to meet different requirements in the application.