Research On Construction Methods Of Periodic And Aperiodic Quasi Complementary Sequence Sets

The quasi-complementary sequence sets(QCSSs)is a new type of complementary sequence proposed in recent years.More users will be supported in a multi-carrier code division multiple access(MC-CDMA)system based on QCSSs.The anti-jamming ability and the number of users in a communication system are determined by the correlation and number of spread spectrum sequences,respectively.Therefore,it is of great significance to design a set of spread spectrum sequences with good correlation performance and large number of sequences.Thesis project mainly focuses on the designing of quasi-complementary sequence sets with good correlation performance.Firstly,the construction method of a class of periodic quasi-complementary sequence sets is proposed.two new types of sequence sets are constructed by using the complex sequence sets given in the literature at first.Then,based on These resultant sequence sets,two kinds of quasi-complementary sequence sets with almost optimal parameters are constructed by using difference sets.Compared with the existing methods,this method obtains some new quasi-complementary sequence sets with new parameter form,and can construct more quasi-complementary sequence sets.Secondly,a construction method of complementary sequence set with aperiodic low correlation zone is proposed.Low correlation zone complementary sequence is a further extension of zero correlation zone complementary sequence,which has more sequences.The proposed method is based on the mapping function and DFT matrix over a finite field,which satisfies specific requirements.At last,a class of complementary sequence sets with low correlation zone is constructed by using these mappings,whose parameters are asymptotically optimal,and the length of correlation region can be flexibly set within a certain range.Finally,the construction method of a class of aperiodic quasi-complementary sequence sets is proposed.The aperiodic quasi-complementary sequences with low correlation are closer to practical application and more difficult to construct.Based on a mapping function over a finite field whose satisfying that there is at most one solution for its polynomial,a method for constructing a class of aperiodic quasi-complementary sequence sets is proposed.The parameters of the constructed quasi-complementary sequence set achieve the theoretical bound.The resultant aperiodic quasi-complementary sequence sets obtained from the proposed method have better and wider range of parameters compared with existing ones.