车车信道的非平稳时频分析以及短时延半实物信道仿真

With the emergence of 5G wireless communications and Device to Device (D2D) technology, the modeling of radio channels in direct Vehicle to Vehicle (V2V) communications between high-speed trains is facing new challenges that the traditional wide sense stationary uncorrelated scattering (WSSUS) channel cannot reflect fast time-varying characteristics caused by the small dimension, the short wavelength and the high-speed motion. The channel semi-physical simulation for communication system performance test should be refreshed as well. In this work, we study the time-frequency representation of the non-WSSUS time-varying channels and derive new second or higher order functions to describe time varying characteristics. Based on geometric modeling and non-stationary time-frequency analysis, small-scale characteristic channels for future V2V communications are established and the communication process is reconstructed. We introduce the channel multiplicative spread factor that enables the modeling of a multiplicative fading channel in a radio frequency band by adopting the non-stationary time-varying functions. The time-varying channel can thus be conveniently emulated by the software defined radio bed. As a result, a new modeling approach for semi-physical channel can be obtained with delay reducing from micro-seconds to nano-seconds.

随着5G通信以及D2D技术到来，高速列车间的车-车直接通信对信道研究提出新问题：广泛应用于信道建模的广义平稳非相关散射信道的描述已经不适合空间小尺度、小波长、高速移动下的快速时变的特性。用于通信系统性能测试的半实物信道仿真随之需要有新技术支撑以满足时变性与实时性需求。为此本项目（1）尝试用时频变换来描述非平稳非相关散射的高速时变信道的统计特性，推导用于表示时变特征的二阶或高阶新函数。（2）用几何建模以及非平稳时频分析方法构建未来车-车通信的小尺度特性信道模型并寻找通信过程重构的方法；（3）提出信道乘性扩展因子的概念，利用非平稳时变函数构造射频频段的乘性衰落信道，将常规的信道仪软件无线电处理输入信号变为软件无线电处理时变信道，使得毫米波半实物无线信道仿真时延由常规等效基带处理需要的微秒级减少到纳秒级。

本项目按照计划执行科研计划，同时将研究的方向由车车通信非平稳信道研究扩展到了5G通信中的MIMO研究以及深入到漏缆的MIMO信道等边缘问题。在隧道泄漏同轴电缆宽带信道的空间特性的研究、矩形隧道移动移动台三维非平稳信道模型、毫米波MIMO信道特性的实验研究以及隧道漏同轴电缆MIMO信道的GSBB模型方面产生有影响的理论成果。项目目标已经全面超额完成。发表SCI论文16篇。“面向轨道交通多业务融合的无线宽带通信关键技术研究与应用”2019年度上海市科技进步奖二等奖第二获奖人。项目负责人主持下，卡斯柯信号公司与上海大学联合建成的“轨道交通无线通信联合实验室”利用项目研究成果研发了具有自主创新的无线信道物理仿真平台和网络通信实验平台，应用于轨道交通信号系统工程建设。获得社会效益5.1亿元。