蜂窝车联网中基于服务异构性的V2V通信资源分配算法研究

在支持车与车直接通信(V2V)的蜂窝网络场景下,针对密集环境下复用车与设备(V2I)上行链路的资源分配问题,在V2V的干扰下,利用移动链路的信道状态信息(CSI)的慢衰落统计,联合通信可靠性、功率控制,建立最大化V2I信道容量的优化模型以满足车辆网络服务的异构性的需求。基于此,该文提出一种基于超图理论和遗传算法的资源分配算法。仿真结果表明,该算法在保证V2V通信可靠性的前提下,提高了V2I的信道容量。     

车联网中的协同通信平均传输时间计算

车联网(Internet of Vehicles,Io V)是智能交通和通信领域的热点课题,协同通信算法的研究是Io V通信的重要技术之一。针对Io V环境下因通信拓扑结构快速变化导致数据信号利用单一通信方式难以高效传输的问题,提出Io V环境下协同通信算法,利用车对车(Vehicle-to-Vehicle,V2V)和车对路(Vehicle-to-Infrastructure,V2I)协同通信方法,对目标数据从请求到完成的平均传输时间进行了理论分析和推导。仿真结果表明,该算法的传输效率比基于移动边缘计算(Mobile Edge Computing,MEC)车联网协作传输算法提升40%,比基于分簇V2X车载广播传输算法提升25%;该算法的平均传输时间随着路侧单元(Road Side Unit,RSU)缓存概率从0.5增加至1可提高9%,随着车辆缓存概率从0.5增加至1可提高46%。     

无人机毫米波信道建模及统计特性研究

针对传统移动信道模型不适用于无人机毫米波通信场景的问题,本文基于射线追踪原理构建了一个无人机毫米波三维几何信道模型,并提出了一种针对该模型的信道参数更新算法,该算法考虑了通信距离、信号角度、路径时延和功率等传播参数的随时间演进过程。在此基础上,针对南京航空航天大学校园传播场景,研究分析了时延分布、时延扩展、角度分布和角度扩展等信道统计特性。数值仿真结果表明,本文模型能够有效复现无人机信道的时变非平稳特性,输出信道统计特性与实测结果吻合,可用于无人机毫米波通信系统的方案设计、性能优化和评估验证等领域。      

基于基扩展模型的UKF-RTSS高可靠鲁棒V2V信道估计

车联网应用场景对无线通信在带宽、时延、可靠性方面提出了更高的需求,特别是车辆对车辆(Vehicle to Vehicle, V2V)场景。针对V2V高速移动场景,时/频域选择性衰落(双选衰落)和非平稳特性给信道估计带来的技术挑战,该文提出了一种基于基扩展模型(Basis Expansion Model, BEM)的UKF-RTSS (Unscented Kalman Filter- Rauch-Tung-Striebel Smoother)信道估计方法。该方法采用BEM拟合快时变信道,将信道参数的估计转化为基函数系数的估计;通过无迹卡尔曼滤波(UKF),联合估计数据处信道冲激响应与时域自相关系数,用于追踪快时变的信道响应。为了进一步提升信道估计的精度,引入RTSS对后向信道状态信息进行信道估计和插值,与UKF构成了“滤波和平滑”结构的UKF-RTSS联合估计器。系统仿真分析表明,在不同速度的快时变条件下,所提方法相比其他经典方法具有更高的信道估计精度和鲁棒性,特别适用于车联网下的无线通信场景。     

塔架环境通信网络信道模型及性能研究

复杂塔架场景无线信道多径效应更为严重,本文结合射线追踪算法提出一种三维多径簇信道模型,该模型通过几何方法追踪每一条射线路径,并对大量接收射线进行分簇,获得簇时延与簇功率等模型参数,进而获得无线通信系统的误码率性能。针对真实的三维塔架分析信道模型参数,包括传播路径、时延、接收功率、误码性能等统计特性。数值仿真结果表明,本文推导理论结果与仿真结果一致,能够准确评估塔架环境的通信性能,可有效用于优化传感器网络的部署和性能评估等领域。      

一种适用于战术通信环境的车对车信道模型

在战术通信环境下,机动车载平台间的无线信道特性更加复杂。传统移动信道模型没有考虑战术场景下的特殊因素对车对车信道的影响,所以此类模型不能应用于战术车载通信系统的设计和优化。为解决传统移动信道模型的局限性,该文提出一种适用于战术通信环境的车对车(Tactical-Vehicle-to-Vehicle, T-V2V)信道模型。该模型充分考虑了实际战术场景中两个车载平台间相互运动、方向性天线的对准问题以及地形地貌等因素对车对车信道的影响,并基于电平通过率(Lever Crossing Rate, LCR)和平均衰落持续时间(Average Duration of Fading, ADF)指标对所提模型进行统计分析。仿真结果表明,所提模型更加贴合战术通信实际情况,能够更为准确地反映出战术通信环境下的车对车信道的变化特性。最后,该文对影响T-V2V信道模型的相关因素进行了仿真分析,所得结果对战术车载通信系统的物理层设计具有重要参考价值。     

三维移动-移动场景非平稳MIMO信道空时相关性

提出一种三维移动-移动场景的非平稳多输入多输出(multi-input multi-output, MIMO)信道模型,该模型改进了不同信道状态之间衰落相位的连续性,可保证输出多普勒频移的正确性。同时,针对该新模型研究了非平稳衰落特性引起的时变空时相关性,并针对收发端信号角度谱服从通用Von Mises Fisher(VMF)分布情况,详细推导了归一化空域互相关函数和时域自相关函数的表达式。最后,针对低速和高速移动两种场景的仿真结果表明,获得的理论结果与数值仿真具有很好的拟合度, 但能极大地减低计算复杂性,进而有效提高了分析和仿真复杂动态场景下MIMO 通信系统的效率。     

两种隧道场景下车对车无线信道衰落特性的测量与分析

针对车-车(vehicle to rechicle, V2V)通信系统对无线电信道衰落特性和模型的需求,分别在两种隧道场景中5.9 GHz和5.2 GHz频段下进行了V2V无线电信道测量活动,并对隧道外、隧道内和两者之间的连接部分场景进行了小尺度衰落特性分析. 基于近距离(close-in, CI)对数模型和ABG (α-β-γ)模型建立了基于距离的接收功率模型,对两种场景隧道内外的接收功率进行了评估和比较,路径损耗指数分别为1.83和1.9,结果表明参考距离为1 m的CI对数模型具有更高的拟合度. 此外,将测量数据幅度的衰落分布与五种典型的理论衰落分布进行比较分析,发现其特征更接近于具有最小拟合优度值的莱斯分布,且隧道内的莱斯K因子小于隧道外. 同时,给出了隧道内和隧道外之间连接处基于距离的莱斯K因子模型,发现连接处的K因子与距离无关,而隧道内的K因子随距离增大而减小.     

基于隧道多散射信道的车载通信系统建模

为建立更高效的智能车对车(Vehicle To Vehicle,V2V)通信系统,针对密集隧道空间多入多出系统(Multiple Input Multiple Output,MIMO)移动传播环境,提出新型三维(Three Dimensional,3D)车载多散射通信信道模型.分析波达信号水平面和仰角平面发射角(Angle Of Departure,AOD)和到达角(Angle Of Arrival,AOA)概率密度分布函数(Probability Density Function,PDF).与以往模型及测量对比,提出模型符合真实隧道环境中无线信道特性,拓展了V2 V通信技术的研究.     

5G宏蜂窝移动通信三维圆柱MIMO多天线系统性能

针对第五代(5G)宏蜂窝移动对移动(M2M)通信场景需要高效率的信号传输模型,提出一种三维(3D)圆柱多输入多输出(MIMO)信道,反映分布区域宏蜂窝传播环境,其中三维圆柱作为信号传输中的干扰对象。接收端(Rx)位于圆柱模型的中心点,发射端(Tx)位于散射区域之外任意位置。接收信号由视距(LoS)传播分量的总和以及由不同物体反射的非视距(NLoS)传播分量组成,该模型能够充分适应各种5G无线通信场景。此外,本文结合莱斯衰落信道、均匀分布、高斯分布、拉普拉斯分布、冯米赛斯分布研究统计信道传播特性,即发射端和接收端在不同的运动方向和运动时间的空间互相关函数(CCF)、时间自相关函数(ACF)和多普勒功率谱密度(PSD)。发射端和接收端在不同时刻的传播特性数值的Matlab分析结果与仿真结果很好地拟合,证明了所提出的三维模型对于真实的5G宏蜂窝移动通信信道是切实可行的。     

Survey of software defined D2D and V2X communication

The related D2D (device-to-device) and V2X (vehicle-to-everything) are regarded as vital components of 5G communication system,which providing alternative network services and multiple application services for cellular network.In the meanwhile,SDN (software defined networking) can improve the compatibilities and flexibilities of D2D and V2X.SD-D2D (software defined D2D communication) and SD-V2X (software defined V2X communication) technologies were reviewed.Based on their similarities and respective characteristics,their state-of-arts and architectures were reviewed accordingly,and the key technologies such as D2D location/discovery management,D2D routing control,D2D flow table management,V2V path scheduling,and V2V path recovery were analyzed.Finally,it was pointed out that the SD-D2D architecture was approaching mature and the SD-V2X framework had been preliminarily determined,the existing problems of interference management,mobile management and routing management in D2D/V2X communication could be effectively solved.Furthermore,it was also pointed out that the disconnection between the existing SD-D2D/V2X studies and the actual application needed to be overcome.     

The Alphasat Aldo Paraboni scientific and communication experiments at Ka and Q/V bands in Austria

The use of higher frequencies for satellite multimedia communication systems calls for research of the atmospheric propagation effects at these bands (rain, cloud and gaseous attenuation, scintillation, and depolarization). Alphasat was successfully launched on 25 July 2013. This largest and most powerful European telecommunication satellite carries, besides a commercial payload belonging to the mobile satellite communication provider Inmarsat, several Technology Demonstration Payloads (TDPs) from ESA. One of them is the Aldo Paraboni payload (TDP5) for Q/V‐band communication and Ka/Q‐band propagation experiments. These experiments explore future applications in satellite communication and measure how the Earth's atmosphere affects the propagation of electromagnetic waves. Under ESA contract, JOANNEUM RESEARCH designed, developed, and operates a Q/V‐band communication ground station and a Ka/Q‐band propagation terminal. The experimental site is equipped with ancillary equipment including a multifrequency radiometer profiler, a 2D video disdrometer (2DVD), and meteorological stations. This paper reports on the experimental setup, data processing, and obtained results.     

宽带车辆到车辆MIMO通信系统性能研究

基于二维（Two-Dimensional,2D）双环和三维（Three-Dimensional,3D）双圆柱体散射模型,在视距（Line-of-Sight,LOS）和非视距（Non-Line-of-Sight,NLOS）场景下,利用宽带2D和3D几何散射模型开展信道仿真,基于实现的MIMO信道矩阵,结合空-频区块编码（Space-Frequency Block Coding,SFBC）和正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）技术,研究了收发终端的移动速度、天线阵元间隔等对宽带车辆到车辆（Vehicle-to-Vehicle,V2V）多输入多输出（Multiple-Input Multiple-Output,MIMO）通信系统误码率（Bit Error Rate,BER）和信道容量的影响.结果表明:随着收发终端移动速度增大,信号衰减加快,宽带MIMO V2V通信系统的BER增大;随着收发端天线阵元间隔的增大,MIMO信道的相关性减小,通信系统的BER减小,MIMO信道的信道容量增大.文中研究方法和结论将对V2V MIMO系统性能分析有一定的指导意义.     

Research on the spatial characterization of a 3D UAV air-to-ground channel model

To cope with the problem that the distribution assumptions of arrival angle and departure angle in existing geometry-based stochastic modeling (GBSM) for the unmanned aerial vehicle (UAV) air-to-ground (A2G) channel are too ideal to describe the spatial statistical property of the UAV A2G propagation environment precisely,considering the three-dimensional (3D) cylindrical A2G channel model,the spatial geometric characteristics of scattering regions were investigated analytically as corresponding to the angles of arrival and departure in both elevation and azimuth planes,which derived the probability density function (PDF) for the distribution of each angle.The effects of various parameters of channel model on the PDF were studied and simulation results prove that the derived PDF can describe the spatial statistical properties of UAV A2G channels more accurately,and can support the modeling of A2G communication channels well.     

V/UHF传播计算模型仿真研究

V/UHF频段在陆地和航空通信中已得到了广泛的应用.文章利用Matlab仿真平台,对自由空间中,平面大地视距路径与非视距路径上的传播损耗计算模型进行了仿真,分析得出了传播损耗与传播距离、通信频率等的关系:针对地空通信,对接收场强进行了仿真,分析得出了接收场强随发射功率、波长,通信距离、飞机高度和地面天线高度的变化关系.较为全面地仿真分析了V/UHF在陆地和地空通信中的传播特性,研究结果对V/UHF在陆地和地空通信中的应用具有一定的参考价值.     

车联网中的V2R通信

无线通信技术的发展对智能交通系统提出了更高的要求。单纯的Ad Hoc网络或者V2V通信不具有可靠性,很多应用不能实现,而V2R通信对于提高可靠性、安全性及舒适度具有重要意义。V2V通信与V2R通信的相互协作可以实现车辆、人和道路间的信息交换,以方便快捷地获取实时道路交通信息,提高旅途的便利性和舒适度。首先分析了V2R通信的特点,对网络的体系结构进行了介绍,然后重点对V2R通信的连通性进行了研究,最后探究V2R通信技术面临的挑战。     

D2D通信中用户意识与信息耦合传播建模分析

设备到设备(D2D)通信中信息传输过程不仅受物理通信条件影响,还与用户动态属性密切相关。为探讨信息传输与用户意识扩散之间的内在关系,该文将信息传输与用户意识扩散视作两种传播过程,并引入过程影响因子刻画两者相互作用。进一步地,建立了一种信息与用户意识耦合传播动力学模型,并进行了全面分析。其中,理论分析证明了模型平衡点的存在唯一性及其全局稳定性,这揭示了D2D通信中信息与用户意识耦合传播的最终状态。实验分析也验证了该理论结果。同时,与传统模型和未考虑过程影响的传播模型对比发现所提模型能扩大信息传播规模且能更准确刻画信息传播过程。     

Doppler-resistant column-wise complementary coded CDMA technology for V2V communications

In Vehicle-to-Vehicle (V2V) communications, the relatively large Doppler-spread poses a great thread to the system performance. In this paper, we propose a new physical layer air-link technology, which combines the advantages of CDMA and OFDM technologies. More specifically, we apply the column-wise complementary codes to the original OFDM-based physical layer design, which can effectively mitigate the Doppler effect under high-speed communication scenarios. The superiority of the new architecture is demonstrated by mathematical analysis and extensive computer simulations. The main contribution of this paper is two-fold. First, the presented analysis provides a more deep insight into the key performance bottleneck in the emerging short-range communications (DSRC) technology. Second, the proposed air link architecture can be implemented with a relatively low implementation complexity, which is desirable for practical applications.     

Alphasat Aldo Paraboni,an advanced Q/V band mission space segment

This paper provides an overview of the space segment of the Aldo Paraboni mission on the Alphasat satellite and the technology programme that has developed one of the most powerful geostationary satellites in Europe. The Aldo Paraboni technology demonstration payload, funded by ASI under European Space Agency's Advanced Research in Telecommunications System Programme, was embarked as a hosted payload on the Alphasat satellite, launched on 25 July 2013. The Aldo Paraboni payload is composed of two main elements, an experimental communication payload operating at Q/V bands (COMEX) and a scientific payload formed by 2 beacons at Ka and Q bands (SCIEX). The Aldo Paraboni payload is a key technology element of the Aldo Paraboni Mission, which covers two main objectives: the communication segment of the mission aims at assessing the performance of satellite communication links at Q/V bands and investigating use Fade Mitigation Techniques (FMT, eg, Adaptive Coding and Modulation defined in DVB‐S2 standard), while the scientific segment aims at characterizing in time, space, and frequency the K and Q band radio channel over Europe to permit development and improvement of propagation channels for slant paths.