高速移动环境下跳频序列部分汉明相关特性的研究

In high-speed mobile frequency hopping (FH) spread spectrum communication systems, FH signals have time delay as well as Doppler shift. In that case, FH signals will be subject to double interference from time delay and Doppler shift. In order to minimize the double interference, designing a class of FH sequences with good properties is an important measure. In real applications, usually the length of the employed FH sequence is shorter than its period. Thus, partial Hamming correlation is more accurate to measure performances of the FH communication systems than periodic Hamming correlation. It is meaningful to study the partial Hamming correlation of FH sequences with Doppler shift. The partial Hamming correlation of them is called time-frequency (TF) 2-dimensional (2D) partial Hamming correlation. The TF 2D partial Hamming correlation properties of FH sequences are studied by properties of Doppler shift in this project. The research topics include: (1) the bound on the TF 2D partial Hamming correlation of FH sequences; (2) the design for FH sequences and low-hit-zone FH sequences with optimal TF 2D partial Hamming correlation by the new bound; (3) the applications of new sequences in high-speed mobile FH spread spectrum communication systems and their performance analysis. It is expected that the research results will benefit space-aeronautics incorporation communications with high frequency.

在高速移动的跳频通信系统当中，跳频信号除了存在传输的时延外，还存在多普勒频率偏移，这时，跳频信号会受到传输时延和频率偏移带来的双重干扰。为了避免这样的双重干扰，设计一组具有优异特性的跳频序列便成为了降低这些干扰的一种重要手段。在实际的跳频序列使用中，通常使用的跳频序列长度远小于序列周期，因此部分汉明相关特性比周期汉明相关特性能更准确地衡量跳频通信系统的性能。研究具有频率偏移特性的跳频序列的部分汉明相关具有一定的价值，该部分汉明相关称之为时频二维部分汉明相关。本课题主要利用频点偏移的序列结构特点研究跳频序列的时频二维部分汉明相关特性，研究内容包括：(1)跳频序列时频二维部分汉明相关的理论界；(2)具有达到理论界最优的时频二维部分汉明相关的跳频序列和低碰撞区跳频序列设计；(3)新型序列在高速移动的跳频通信系统中的应用及其性能分析。希望该研究成果能为高频段和空天一体化通信带来一些价值。

在准同步跳频通信系统中，低碰撞区跳频序列起到很关键的作用，而具有宽间隔特性的跳频序列可有效对抗宽带阻塞干扰、跟踪干扰等。本项目主要研究低碰撞区跳频序列的理论界与相应的构造。首先建立了无碰撞区跳频序列集在非周期汉明相关函数下的理论界并构造了相应的最优序列，提出了新型准同步跳频序列的概念并给出了相应的构造。然后，建立了低碰撞区跳频序列集平均汉明相关的理论界并且构造了两类满足该界最优的低碰撞区宽间隔跳频序列集。利用中国剩余定理构造了具有宽间隔特性的最佳无碰撞区跳频序列集，建立了严格无碰撞区宽间隔跳频序列集更紧的理论界并给出了最佳的构造，提出了宽间隔区跳频序列集的概念并导出了其最大周期汉明相关的理论下界，同时给出了最佳构造。最后，研究了新型跳频序列在相关领域和系统中的应用。这些新型跳频序列对于高速移动环境下的多普勒频率偏移带来的频点干扰有很好的抑制效果。