高铁毫米波通信与雷达探测波束赋形技术

发布时间：2018-12-13 05:50

【摘要】：高速铁路的通信系统分为用于列车调度控制的专用无线通信系统和用于列车上乘客接入互联网的宽带无线通信系统。目前用于铁路调度控制的无线通信系统绝大多数采用的还是GSM-R系统,列车上的乘客接入互联网主要还是依靠公网。然而,公网的移动性能远远不能满足乘客对网络速度与质量的要求,开发新的频段用于高速铁路无线通信成为必要。铁路无线通信系统向下一代移动通信系统演进势在必行,相应的是大规模的基站等基础设施的更新与替换。此外,我国的高铁经常穿行于偏僻、环境恶劣的山区,滑坡、泥石流等自然灾害长期威胁着铁路运营的安全,适用于高铁场景下的灾害监测技术也亟待研究。毫米波由于能够实现超高速数据传输速率,在下一代无线通信系统中具有巨大潜能;由于资源丰富,探测精度高,在雷达探测领域的研究也具有重大意义。将毫米波通信与探测技术集成于一个基站,使其成为集提供高速率的无线传输功能以及灾害监测与预警功能为一体的安全基站。雷达设备与通信设备共站址,共基带,共回传,此安全基站设备不易受到破坏,且具有系统成本较低、探测效率高等优势。因此,本文基于C-RAN(Cloud-Radio Access Network)的通信与探测融合架构,对毫米波特性以及毫米波波束赋形技术的研究具有极大的理论及现实意义。为进一步提高通信和探测系统的性能,本文对毫米波传输特性、波束赋形技术以及探测波束扫描方案等进行了深入研究。首先,引入基于C-RAN的毫米波通信与探测融合架构,从毫米波传输特性和探测分辨率需求两个角度研究融合系统的适用频段,同时研究了毫米波通信与探测范围和发射功率的关系。波束赋形技术对于高铁毫米波通信至关重要,因此,本文接着详细研究了适用于高铁场景的机会波束赋形技术。首先,对波束赋形的原理、波束宽度的影响因素进行了介绍和分析。然后,介绍了两种机会波束赋形技术,分析了基站天线数量和车载台个数以及DOA估计误差对于波束赋形带来的系统增益的影响。另外,在此基础上提出了基于位置信息的单双流切换波束赋形技术来进一步提升系统性能,并且结合两个波束间的干扰因子和单双波束的系统容量研究合适的单双波束的切换点。为了提高集成系统的灾害探测效率,本文提出了一种灾害探测自适应波束赋形方案。首先基于毫米波传输特性以及探测需求提出了分频多波束探测方案,在此基础上提出了一种自适应波束扫描方式,并且不同的探测区域采用不同的波束探测方案。由仿真分析可知,本文所提的自适应波束赋形方案既可以满足各个区域的探测预警需求,也可以在一定程度上减少系统的复杂度,是一种有效的灾害探测波束赋形方案。
[Abstract]:The communication system of high-speed railway is divided into a special wireless communication system for train dispatching and control and a broadband wireless communication system for connecting passengers on a train to the Internet. At present, most of the wireless communication systems used in railway dispatching and control are still GSM-R system, and the passengers on the train mainly rely on public network to connect to the Internet. However, the mobile performance of the public network is far from meeting the requirements of the speed and quality of the network, so it is necessary to develop a new frequency band for high-speed railway wireless communication. It is imperative for the railway wireless communication system to evolve to the next generation mobile communication system. In addition, the natural disasters such as landslide, debris flow and other natural disasters that often travel through remote and harsh mountain areas in China threaten the safety of railway operation for a long time, and the disaster monitoring technology suitable for high-speed railway scene also needs to be studied urgently. Millimeter-wave has great potential in the next generation wireless communication system because of its ability to realize ultra-high speed data transmission rate. Because of its rich resources and high detection precision, it is also of great significance in the field of radar detection. The millimeter-wave communication and detection technology is integrated into a base station, which can provide high rate wireless transmission function, disaster monitoring and early warning function as one of the security base station. Radar equipment and communication equipment are co-located, common baseband, common transmission, this security base station equipment is not easy to be damaged, and has the advantages of low system cost, high detection efficiency and so on. Therefore, based on C-RAN (Cloud-Radio Access Network) communication and detection fusion architecture, this paper has great theoretical and practical significance for the study of millimeter-wave characteristics and millimeter-wave beamforming technology. In order to improve the performance of communication and detection system, the transmission characteristics of millimeter wave, beamforming technology and scanning scheme of detecting beam are studied in this paper. Firstly, a millimeter-wave communication and detection fusion architecture based on C-RAN is introduced to study the applicable frequency band of the fusion system from the aspects of millimeter-wave transmission characteristics and detection resolution requirements. At the same time, the relationship between millimeter wave communication and detection range and transmission power is studied. Beamforming technology is very important for high speed millimeter-wave communication. Therefore, the opportunistic beamforming technique suitable for high-speed train scenarios is studied in detail in this paper. Firstly, the principle of beamforming and the influencing factors of beamwidth are introduced and analyzed. Then, two kinds of opportunistic beamforming techniques are introduced, and the effects of the number of base station antennas, the number of vehicle stations and the DOA estimation error on the system gain caused by the beamforming are analyzed. In addition, a new beamforming technique based on position information is proposed to further improve the performance of the system. Combining the interference factor between two beams and the system capacity of single and double beams, the suitable switching points of single and double beams are studied. In order to improve the disaster detection efficiency of the integrated system, an adaptive beamforming scheme for disaster detection is proposed in this paper. Based on the characteristics of millimeter-wave transmission and the detection requirements, a frequency-division multi-beam detection scheme is proposed, and an adaptive beam scanning scheme is proposed, and different beam detection schemes are used in different detection regions. The simulation results show that the proposed adaptive beamforming scheme can not only meet the detection and early warning needs of each region but also reduce the complexity of the system to a certain extent. It is an effective beamforming scheme for disaster detection.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN928;TN95

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