【作者】 陈雷；

【导师】 贾志成；

【作者基本信息】 河北工业大学 ， 物理电子学， 2005， 硕士

【摘要】 移动通信的发展当前正处于一个关键时期,新的业务和技术正不断涌现,客户的需求也在不断增长。同时,因特网迅速发展成为真正的超级信息高速公路,无线业务也在迅速增长。由于网络的发展,数据和多媒体通信发展迅猛,所以第三代移动通信的目标是宽带通信,也就是扩频通信。 在扩频通信系统中,主要使用二元序列作为扩频码。二元序列的研究已经较为广泛和深入。但二元序列却存在着如地址码数量过少,相关性能改善程度已趋近于零等缺点,从而无法适应移动用户数量的不断增加且无法满足用户对通信质量不断提高的要求。为了改变这种现状,众多学者开始研究多相序列作为扩频码,其中以日本学者Naoki Suehiro的多相序列理论较为典型。按其构造方法得到的多相序列具有更优秀的相关性能,进而能够得到更多的地址码数量。 文中对多相序列的相关性进行了深入研究,提出了一种基于多相正交序列的扩频通信系统的调制解调方法,并对采用此种调制解调方法的通信系统的自相关接收性能和抗多址干扰性能进行了分析。在此基础上提出采用多相完全互补序列作为扩频序列进行CDMA通信的通信方式,文中分别研究了基于多相完全互补序列的两种通信方式,即串行时分通信方式和并行多载波通信方式。并证实了这种基于多相完全互补序列的CDMA系统可以克服移动通信中存在的多址干扰和多径效应。 多相正交序列的自相关特性非常理想,但在低相数时,互相关特性不够理想。虽然随着序列相数的增加,满足互相关要求的序列组中独立地址码数量在不断增加。然而,在高相数序列组的搜索上计算量过大,目前尚存在一定困难。本文提出将同一多相正交序列的各个具有不同初始相位的移位序列分配给不同用户作为地址码,利用多相正交序列理想的自相关特性进行码分多址通信。 最后,文中指出了多相正交序列理论以及工程应用中存在的一些问题,并对今后多相序列的研究方向进行了展望。更多还原

【Abstract】 Mobile communication is in a key period of development. New operation and technology are coming forth. At the same time, Internet is being a true information high way and the wireless operation is increasing. Communication of data and multimedia is developing rapidly. Therefore, the target for third generation mobile communication is spread spectrum communication.In spread spectrum communication, the main address codes are duality sequences. The research for duality sequences have been abroad and thoroughly. But the duality sequences have some disadvantages that there are few address-codes and the correlation properties can not be improved further. Therefore, the require for increase of mobile users and higher communication quality can not be satisfied. To change the actuality, a lot of scholars begin to study polyphase sequences. The polyphase sequences construction method of Naoki Suehiro from Japan is typical. According this method, polyphase sequences with more excellent correlation properties can be got and more address-codes can also be got.In this paper, the correlation properties of polyphase sequences are studied thoroughly and an new method of modulation and demodulation is given. The capacity of auto-correlation and anti-MAI for this method is analysed. Two communication modes for CDMA based on polyphase complete complementary sequences are given. The conclusion that this system can overcome the MAI and multipath impact in mobile communication is given.The properties of auto-correlation for polyphase orthogonal sequences are very ideal, but its cross-correlation properties are not good when the phase number is low. Although the number of independent address can satisfy the request with the increase of phase, the searching time is too long. In this paper, the shift sequences of polyphase orthogonal sequences are distributed to different user and the ideal auto-correlation properties are utilized for CDMA communication.Finally, in this paper some problems for theory and application of polyphase orthogonal sequences are pointed out. The main direction of research for polyphase orthogonal sequences is given.更多还原