宽带扩频通信系统中具有最佳相关特性的扩频序列偶设计研究

With the increasing demands on multimedia information services of communication users, realization of high speed, high spectral efficiency and high anti-interference of the wideband spread spectrum communication system has become increasingly urgent. In addition, the characteristics of spreading sequences determine the theoretical performances on capacity, anti-interference and data transmission rate of spread spectrum communication system. The facts that perfect spreading sequences existing in small numbers, while the correlation of quasi-perfect spreading sequence being not optimal and data transmission rate being limited, which have become a bottleneck of the development of spread spectrum communication technology. In this project, the sequence numbers and correlation property are selected as the key elements while studying the sequences design methods for the wideband spread spectrum communication system. At the same time, this study focuses on the system capacity and the interference suppression problem. The design methods for the Gaussian integer sequences with the perfect autocorrelation property are studied, more perfect sequences with good balance property and high degree of freedom can be obtained by extending the elements domain; the design methods for the periodic (aperiodic) binary and the Gaussian integer complementary sequences are studied， accomplishing the best combination of the complementary sequences and the mismatched sequences and the ideal sequences are produced for CDMA and OFDM systems; the design methods for the Gaussian integer grouped complementary sequence pair sets with a large number and optimal correlation property are researched , the ideal correlation property of both within each sequence group and inter-group can be achieved. Through the research of this project, it is expected to attain much more new spreading sequences with a large number and good correlation property and to promote wideband spread spectrum communication to realization of high data rate, high spectrum efficiency and high anti-interference communication and further enrich the sequence design theory system.

随着多媒体信息业务增加，高速率、高频谱效率、高抗干扰宽带扩频通信需求变得日益紧迫。扩频序列决定扩频系统在系统容量、抗干扰性和通信速率方面理论性能。最佳扩频序列少、近似最佳扩频序列相关性不佳、通信速率受限成为制约宽带扩频通信发展的瓶颈。项目针对宽带扩频通信序列设计，以序列数目和相关性为关键要素，围绕系统容量和干扰抑制问题展开。研究具有最佳自相关特性高斯整数序列偶设计方法，利用元素域扩展获得更多平衡性好、自由度高的最佳序列；研究(非)周期二进制和高斯整数互补序列偶设计方法，实现互补序列与失配序列最佳结合，产生适用于CDMA和OFDM的理想序列；研究具有大序列数目和最优相关性的分组互补高斯整数序列偶集设计方法，使各序列偶组内和组间均具有理想相关性。通过本项目研究，有望构造出更多存在空间大、相关性好的新扩频序列，推动宽带扩频通信向高速率、高频谱效率、高抗干扰方向发展，并进一步丰富序列设计理论体系。

随着多媒体信息业务增加，高速率、高频谱效率、高抗干扰宽带扩频通信需求变得日益紧迫。项目针对宽带扩频通信序列设计，以序列数目和相关性为关键要素，围绕系统容量和干扰抑制问题展开研究，主要完成了以下几部分的内容：(1)二进制序列由于实现简单被广泛使用同时也是研究其它类型序列的基础，基于理想二进制序列和理想二进制序列偶，结合中国剩余定理，对周期为偶数的几乎最佳二进制序列偶的构造方法进行了研究，得到的几乎最佳二进制序列偶突破了现有几乎最佳二进制序列长度必须是4的倍数的限制；通过在0位置引入一个0元素的方式，基于四阶分圆的方法，得到了周期为偶数且相关函数值为{0,-2}和{0,2,-2}的理想几乎二进制序列，拓展了现有偶数长理想二进制序列的存在范围。(2)基于组合设计理论及结合中国剩余定理的方法，对具有低自相关特性的偶数长度的四进制序列和具有理想自相关特性的几乎四进制序列的构造方法进行了研究，这些方法都属于直接构造方法，得到的四进制序列不仅具有好的自相关特性且具有好的平衡性；基于差集的方法提出了可得到4种新类型的自由度为4且平衡的最佳高斯整数序列偶的构造方法；基于差集偶的方法，给出了一种能得到自由度为2的最佳高斯整数序列偶的通用构造方法，得到的这些最佳高斯整数序列(偶)应用到OFDM系统中均能很好的降低系统的PAPR。(3) 针对周期二进制互补序列周期必须为偶数的限制，基于偶理论，结合广义分圆类，给出了两种可以得到周期为3q(q为素数)的互补序列的直接构造方法，弥补了目前周期二进制互补序列的存在的局限性。(4)针对多载波CDMA信号峰均功率比过高及互补码集合容量受限的问题，基于移位组合法和正交矩阵，构造了多个可以灵活选择参数的高斯整数零相关区周期互补序列集，基于差集和几乎差集，提出了几类具有低相关性和大容量的准互补序列集的构造方法，应用到多载波CDMA可以在降低干扰的同时支持更多的通信用户。本项目共发表论文11篇，其中SCI期刊论文6篇，EI收录论文10篇。