【摘 要】
：
近些年来，随着移动通信技术的不断发展以及高速铁路的在全球的全面普及，人们对于高铁移动通信的提出了更高的要求，传统的高铁移动通信已经不能满足当前的通信需求。目前解决高铁移动通信的方案归纳为两大类:一是在列车经过的沿线铺设大量的通信基站、直放站或者是通信电缆等，利用类似于蜂窝覆盖的方式实现高铁移动通信;二是利用卫星通信的大面积覆盖实现高铁移动通信。这两种方案各有优缺点，本文提出的将平流层通信应用到高铁
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近些年来，随着移动通信技术的不断发展以及高速铁路的在全球的全面普及，人们对于高铁移动通信的提出了更高的要求，传统的高铁移动通信已经不能满足当前的通信需求。目前解决高铁移动通信的方案归纳为两大类:一是在列车经过的沿线铺设大量的通信基站、直放站或者是通信电缆等，利用类似于蜂窝覆盖的方式实现高铁移动通信;二是利用卫星通信的大面积覆盖实现高铁移动通信。这两种方案各有优缺点，本文提出的将平流层通信应用到高铁移动通信中具有二者的优点而克服其缺点。智能天线技术作为一种新型的移动通信技术得到广泛的发展和应用。自适应阵列天线技术是其一个重要组成部分。利用自适应阵列天线可以实现对于天线辐射波束的有效控制，当天线的波束实时指向移动目标时，其实质是提高了通信的信号增益，从而提高信号传输质量，提高通信效率，即所谓的自适应波束形成技术。波束形成的算法基于不同的准则有很多种，最常见的基本算法有LMS和RLS自适应波束形成算法。本文提出的基于频域的可变步长的LMS自适应波束形成算法具有收敛速度快，收敛稳定的特点，并且算法还具有一定的抗相干性。本文在全面研究高铁移动通信的基础上,提出将平流层通信应用到高铁移动通信中的设想,并论述了该方案的可行性和优势.在平流层通信平台与地面高铁列车建立通信的过程中,利用自适应阵列天线形成可变的波束跟踪列车,可以有效的提高通信的质量和效率.本文还提出了一种基于频域的可变步长的自适应波束形成算法,并对该算法进行了仿真实验,证明该算法具有收敛快、抗相干的特点.
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