Research And Design Of High Spectrum Efficiency Spread Spectrum Sequences

The interference of CDMA communication system will reduce its performance,and complementary sequences with ideal correlation characteristics can effectively suppress system interference.Therefore,the design of complementary sequences has drawn extensive attention,especially for the design of the high spectral efficiency QAM+ complementary sequence sets.The QAM+ complementary sequence sets not only inherit the ideal correlation property of the complementary sequences,but also have high transmission rate and strong anti-interference ability,so the system performance can be improved.This dissertation mainly studies the construction method of 16-QAM+ periodic complementary sequence sets with high spectral efficiency.Firstly,the new mappings from binary sequences to 16-QAM+ sequences are designed.By combining the binary periodic complementary sequence sets with the novel mappings,two methods of the constructing 16-QAM+ periodic complementary sequence sets are proposed.And the two methods can generate three new types of 16-QAM+ periodic complementary sequence sets according to the difference in the number of complementary sequences selected.The number of subsequences in the resulting sequence sets has been extended to different degrees,making their characteristics more excellent.Then,based on the ternary perfect sequence and the 16-QAM periodic complementary sequence set,combined with the correlation function of the design,a designing method of the 16-QAM+ periodic complementary sequence set is proposed.The obtained results not only further extend the length of the subsequences,but also the complement sequences are mates each other,which improve the cross-correlation properties of the sequences.The above design method is improved.Using the specific correlation function,the ternary periodic complementary sequence set and the 16-QAM periodic complementary sequence set are combined to obtain a type of 16-QAM+ periodic complementary sequence set.In the resulting 16-QAM complementary sequences set,not only the complementary sequences are mates each other,but also the number of complementary sequences,the number of subsequences,and the length of the subsequences are all extended.Therefore,the obtained result has more ideal characteristics and is more in line with the conditions of application in the multi-user communication field.Finally,the designed 16-QAM+ periodic complementary sequence set is applied to the multi-carrier direct-sequence CDMA system,and the performance is compared with the traditional sequence-based multi-carrier direct-sequence CDMA system.Simulation results show that the resulting 16-QAM+ periodic complementary sequence set can improve system performance.The results obtained in this paper provide more optional high spectral efficiency spreading sequence sets for communication engineering applications.At the same time,the new mapping functions designed expand the idea for the study of the next QAM+ sequences.