Polyphase Periodic Sequence And Search Of Better Sequence Series

With the advanced technology, the frequency usage efficiency is the most important. CDMA technique becomes the research hotspot in the communication, therefore, coding technique's importance stands out especially. In this paper, a kind of polyphase orthogonal sequence's construction method and its properties are studied. The study is based on the FH sequence's properties and the theory of construction of polyphase orthogonal sequence proposed by Naoki Suehiro. Based these studies, the searching method of better sequences is discussed and the searching in quadri-phase and six-phase orthogonal sequences goes along.In this paper, the concepts, properties and applications in practice of polyphase sequence, periodic sequence and periodic complementary that related to the polyphase orthogonal sequence is presented. A kind of ,/V-phase orthogonal sequence which periodic is N2 is proposed in detail, and it is proved that the correlation properties of the sequence is ideal and the sequence is /V-shift cross-orthogonal sequence. According to CDMA system's require for the address sequence, the series of sequences of better cross-correlation property is searching.The search upon quadri-phase and six-phase orthogonal sequences is made in time-domain at first. Owing to combination bomb, it expends space and time largely. In order to realize fast searching, correlation property of the periodic sequence in frequency domain is made full use and the better series of sequences is received. And then, the searching method is discussed to some extend in fact.Through the studies of the properties of polyphase sequences and result of the search, it comes to the conclusion that the correlation property of this kind of sequence and its number as well as its length can satisfy the need of spread sequence to some extend.