3D non-stationary geometry-based stochastic model for unmanned aerial vehicle air-to-ground multi-input multi-output channels

A three-dimensional non-stationary geometry-based stochastic model for unmanned aerial vehicle(UAV)air-to-ground multi-input multi-output(MIMO)channels is proposed.The scatterers surrounding the UAV and ground station are assumed to be distributed on the surface of two cylinders in the proposed model.The impact of UAV rotations and accelerated motion is considered to describe channel non-stationarity.The computational methods of the corresponding time-variant parameters,such as UAV antenna array angles,time delays,and maximum Doppler frequencies,are theoretically deduced.The model is then used to derive channel statistical properties such as space-time correlation functions and Doppler power spectral density.Finally,numerical simulations are run to validate the channel s statistical properties.The simulation results show that increasing the UAV and ground station accelerations can reduce the time correlation function and increase channel non-stationarity in the time domain.Furthermore,the UAV s rotation significantly influences the spatial correlation function,with rolling having a greater influence than pitching.Similarly,the different directions of UAV movement significantly impact the Doppler power spectral density.

Polarization Projection for 3D Geometry-Based Stochastic Channel Model

Comprehensive radiation characteristics of polarized antenna are crucial in creating practical channel coefficients for next generation wireless communication system designs.Being currently supported within3 D geometry-based stochastic channel models(GSCM),field patterns are technically obtained by chamber measurement(or by its best fitting).However,in some channel related performance analysis scenarios,design insight can be crystallized better by starting the derivations with theoretical co-polarization and cross-polarization components.Specifically,these two components are mathematically linked with field patterns through the proposed polarization projection algorithm.In this manuscript,we focus on revealing the transformation criterion of polarization states between the antenna plane and the propagation plane.In practice,it makes retrieving the field patterns by electromagnetic computation possible.Meanwhile,the impact imposed by distinct antenna orientations is geometrically illustrated and consequently incorporated into the proposed algorithm.This will further facilitate flexible performance evaluation of related radio transmission technologies.Our conclusions are verified by the closed-form expression of the dipole field pattern(via an analytical approach) and by chamber measurement results.Moreover,we find that its 2D degenerative case is aligned with the definitions in 3^(rd) generation partnership project(3GPP)technical report 25.996.The most obvious benefit of the proposed algorithm is to significantly reduce the cost on generating channel coefficients in GSCM simulation.

A Novel 3D Non-Stationary UAV-MIMO Channel Model and Its Statistical Properties

The wireless communication systems based on Unmanned Aerial Vehicles(UAVs) have found a wide range of applications recently. In this paper, we propose a new three-dimensional(3 D) non-stationary multiple-input multiple-output(MIMO) channel model for the communication links between the UAV and mobile terminal(MT). The new model originates the traditional geometry-based stochastic models(GBSMs) but considers the non-stationary propagation environment due to the rapid movements of the UAV, MT, and clusters. Meanwhile, the upgrade time evolving algorithms of time-variant channel parameters, i.e., the path number based on birth-death processes of clusters, path delays, path powers, and angles of arrival and departure, are developed and optimized. In addition, the statistical properties of proposed GBSM including autocorrelation function(ACF), cross-correlation function(CCF), and Doppler power spectrum density(DPSD) are investigated and analyzed. Simulation results demonstrate that our proposed model provides a good agreement on the statistical properties with the corresponding derived theoretical ones, which indicates its usefulness for the performance evaluation and validation of the UAV based communication systems.

基于随机几何的变电站无线通信信道模型

无线通信技术与变电站紧密融合,是保障变电站正常运行的重要因素之一。由于变电站电气设备密集多样、移动通信终端信号传输路径复杂,传播特性有别于经典无线通信场景。为此,基于随机几何建模法(geometry-based stochastic model,GBSM),从变电站实际场景出发,将其抽象为圆形栅柱的几何模型;模拟设备密集区域视距(line of sight,LOS)分量少的现象,设置LOS与非视距(non-line of sight,NLOS)子区,推导模型的空时相关函数(space-time correlation function,ST-CF),空间互相关函数(cross-correlation functions,CCF)和时间自相关函数(auto-correlation functions,ACF)的数学表达式,搭建出适用于变电站室外典型结构的随机几何信道模型。参考模型与仿真模型结果验证了该3D圆形栅柱随机几何模型具有可行性。实验结果表明LOS、散射体分布和多普勒效应对变电站室外无线信道特性有较大影响。

基于几何的高速铁路协作MIMO信道建模

协作MIMO技术通过协作发射或协作接收的方式可以将干扰信号转变为有用信号,在高铁无线通信中引入该技术,能解决回波信道响应和提高系统容量。为了掌握协作MIMO技术在高铁场景中的信道特性,该文基于几何随机散射理论,提出一个高速铁路协作MIMO信道模型,简单调整该模型中的几个关键参数即可适用于高速铁路的多种场景。基于该模型计算信道冲激响应,推导多链路空间相关函数,进行数值计算、仿真分析和实测数据验证。仿真结果显示,直射分量越强,散射分量的角度扩展越小,多链路的空间相关性越强。散射次数越少,散射分量空间相关性越强。使用北京-天津高铁段LTE专网的实测数据验证理论模型的正确性。这些结论有助于认知协作MIMO信道和进行有效的测量活动。

基于轨迹的车对车无线信道建模及硬件模拟

针对车对车通信信道场景复杂多变且不易用硬件模拟复现的特点,通过引入车辆行驶速度及方向二维参数,构建了一种基于几何随机方法的非平稳多输入多输出信道简化模型,该模型可支持移动发射端和移动接收端任意运动轨迹。在此基础上,设计并实现了一个基于现场可编程逻辑阵列器件硬件平台的车车信道模拟器方案,并给出了离散化信道参数的计算和硬件模拟方法。实测结果表明,该模拟器输出的时延功率谱和多普勒功率谱能够有效模拟车车动态场景下信道的非平稳特性,并且与理论仿真结果相吻合,因而可用于车载通信设备的方案验证、算法优化和性能测试等领域。

Inter-carrier Interference Analysis for MIMO-OFDM Systems in High-Speed Train Environment

The orthogonality between the subcarriers of multipleinput multiple-output orthogonal frequency division multiplexing( MIMO-OFDM) systems is destroyed due to the Doppler frequency offset,particularly in the high-speed train( HST) environment,which leads to severe inter-carrier interference( ICI). Therefore,it is necessary to analyze the mechanism and influence factor of ICI in HST environment. In this paper, by using a non-stationary geometry-based stochastic model( GBSM) for MIMO HST channels, ICI is analyzed through investigating the channel coefficients and the carrier-to-interference power ratio( CIR). It is a fact that most of signal energy spreads on itself and its several neighborhood subcarriers. By investigating the amplitude of subcarriers, CIR is used to evaluate the ICI power level. The simulation results show that the biggest impact factor for the CIR is the multipath number L and the minimum impact factor K; when the train speed υR> 400 km / h,the normalized Doppler frequency offset ε > 0. 35,the CIR tends to zero,and the communication quality will be very poor at this condition. Finally,bit error rate( BER) is investigated by simulating a specific channel environment.

Characteristics and modeling of UAV-vehicle MIMO wideband channels

A geometry-based stochastic model(GBSM) for unmanned aerial vehicle to vehicle(UAV-V) multiple-input multiple-output(MIMO) wideband channel is proposed to investigate the characteristics of UAV-V channel. Based on the proposed model, a three-dimensional(3D) wideband channel matrix regarding channel numbers, time and delay is constructed. And some important channel characteristics parameters, such as power delay profile(PDP), root mean square(RMS) delay spread, RMS Doppler spread, channel gain and Doppler power spectral density(PSD) are investigated with different vehicle velocities. It is much simpler and clearer compared with the complex analytical derivations. The results are compared with validated analysis to confirm the theoretical analysis.