Research On Complete Complementary Sequence And Moudulation And Simulation Methods Of Polyphase Orthogonal Sequence

With the development of information society, information transmitted in communication system are no only speech signal but also image and data and much higher transmitting speed are highly expected. So conventional communication system can not meet the requirement of society in future. With more advantages than wireless communication technologies such as GSM, CDMA(code division multiple access) technology are attracting more and more attention. As a key technique, coding technique's importance stands out especially.At present, the research in spectrum spread field focus on duality sequences, for example m and gold sequences in CDMA. But there are some limitation for duality sequences which has ideal correlation property to chose the period of sequences spread and the numbers of sequences spread is small. To meet the request of practice, more and more people began to pay more attention to polyphase sequences that are formed by signal with more sequences and ideal correlation property.In this paper, a kind of polyphase orthogonal sequence is introduced based on the polyphase sequences theory proposed by N.Suehiro and its correlation and polyphase properties was investigated. Then, a kind of construction method amended of complete complementary is proposed for improving correlation property, and it's validity is verified.The duality sequences was generated from shift register and its length can be adjusted by hardware. However, the length of polyphase sequences is restricted by number of phase N in terms of the method proposed by Suehiro, For example, when N is 4,the length is 16. The only way to expand the length is to set one bigger value of N, but there will be much more difficulties. So, the concept of pseudo-periodic sequences is introduced without changing the construction method to satisfy the demand for spectrum spread coding.The mission to study polyphase sequences is to find some address codes which satisfy the demand of spectrum spread technology. For many years, the theory research of duality sequences and its applications in engineering practice is consummated day by day. The research of polyphase sequences will be put into practice finally although the research at present is mainly focus on theoretics. So, the modulation and simulation of spread spectrum system was studied in this paper and a kind of method of modulation based on polyphase orthogonal sequences is proposed, then it's feasibility is discussed.