Analysis and Solution of Multipath Effect on Wireless Communications of Launch Vehicle

The electrical system in a launch vehicle contains multiple wireless communications systems. A large number of prelaunch tests are needed to verify the correctness and reliability of electric systems at the launch site. The complex electromagnetic environment at a launch site will inevitably cause multipath effect which interfere with prelaunch tests. Theory analysis and simulation of multipath effect, combined with engineering practice, can effective identify and quickly correct abnormal situations, and identify methods and measures to eliminate the influence of multipath interference.

Placement of unmanned aerial vehicles as communication relays in two-tiered multi-agent system:clustering based methods

The network performance and the unmanned aerial vehicle(UAV)number are important objectives when UAVs are placed as communication relays to enhance the multi-agent information exchange.The problem is a non-deterministic polynomial hard(NP-hard)multi-objective optimization problem,instead of generating a Pareto solution,this work focuses on considering both objectives at the same level so as to achieve a balanced solution between them.Based on the property that agents connected to the same UAV are a cluster,two clustering-based algorithms,M-K-means(MKM)and modified fast search and find density of peaks(MFSFDP)methods,are first proposed.Since the former algorithm requires too much computational time and the latter one requires too many relays,an algorithm for the balanced network performance and relay number(BPN)is proposed by discretizing the area to avoid missing the optimal relay positions and defining a new local density function to reflect the network performance metric.Simulation results demonstrate that the proposed algorithms are feasible and effective.Comparisons between these algorithms show that the BPN algorithm uses fewer relay UAVs than the MFSFDP and classic set-covering based algorithm,and its computational time is far less than the MKM algorithm.

Integrated Sensing and Communication Enabled Multiple Beamwidth and Power Allocation for Connected Automated Vehicles

Connected autonomous vehicles(CAVs)are a promising paradigm for implementing intelligent transportation systems.However,in CAVs scenarios,the sensing blind areas cause serious safety hazards.Existing vehicle-to-vehicle(V2V)technology is difficult to break through the sensing blind area and ensure reliable sensing information.To overcome these problems,considering infrastructures as a means to extend the sensing range is feasible based on the integrated sensing and communication(ISAC)technology.The mmWave base station(mmBS)transmits multiple beams consisting of communication beams and sensing beams.The sensing beams are responsible for sensing objects within the CAVs blind area,while the communication beams are responsible for transmitting the sensed information to the CAVs.To reduce the impact of inter-beam interference,a joint multiple beamwidth and power allocation(JMBPA)algorithm is proposed.By maximizing the communication transmission rate under the sensing constraints.The proposed non-convex optimization problem is transformed into a standard difference of two convex functions(D.C.)problem.Finally,the superiority of the lutions.The average transmission rate of communication beams remains over 3.4 Gbps,showcasing a significant improvement compared to other algorithms.Moreover,the satisfaction of sensing services remains steady.

A New Compact Omni-Directional Quasi-Self-Complementary Antenna for Wireless Communication Systems

This article describes a new miniaturized omni-directional antenna with quasi-self-complementary structure for wireless communication applications. A novel ground structure composed of five rectangular plates is proposed to enhance the impedance bandwidth and reduce the antenna size. The proposed antenna is comprised of two patches surrounded by the ground structure. Two metal patches of the antenna are located on two opposite sides of the dielectric substrate. The feed patch is used to excite the radiation patch. This unique design is realized by properly choosing the suitable feed patch shape, selecting similar slot shape on the radiation patch, and tuning their dimensions. The proposed antenna with an extremely small size of 6 mm × 9 mm has an operating impedance bandwidth ranging from 4.5 to 6.1 GHz for S11 < -10 dB, which also covers the two IEEE 802.11a wireless local area network bands (5.15 - 5.35 GHz and 5.725 - 5.825 GHz). In addition to be very small in size, the antenna exhibits omni-directional radiation patterns in the entire operating bandwidth and low cross polarization. The distortionless time domain performance of the antenna is confirmed by investigation of the phase response and group delay. The obtained results in both frequency and time domain show that the proposed antenna is suitable for use in wireless communication systems.

The Innovation and Development of Internet of Vehicles

With the advancements in wireless sensor networks, Internet of Vehicles(IOV) has shown great potential in aiding to ease traffic congestion. In IOV, vehicles can easily exchange information with other vehicles and infrastructures, thus, the development of IOV will greatly improve vehicles safety, promote green information consumption and have a profound impact on many industries. The purpose of this paper is to promote the innovation and development of IOV. Firstly, this paper presents general requirements of IOV such as guidelines, basic principles, and the goal of development. Secondly, we analyze critical applications, crucial support, and business model to promote the industrial development of IOV. Finally, this paper proposes some safeguard measures to further promote the development of IOV.

Unmanned Drug Delivery Vehicle for COVID-19 Wards in Hospitals

The prime reason for proposing the work is designing and developing a low-cost guided wireless Unmanned Ground Vehicle(UGV)for use in hospitals for assistance in contactless drug delivery in COVID-19 wards.The Robot is designed as per the requirements and technical specifications required for the healthcare facility.After a detailed survey and tests of various mechanisms for steering and structure of UGV,the best mechanism preferred for steering articulated and for body structure is hexagonal as this approach provides decent performance and stability required to achieve the objective.The UGV has multiple sensors onboard,such as a Camera,GPS module,Hydrogen,and Carbon Gas sensor,Raindrop sensor,and an ultrasonic range finder on UGV for the end-user to understand the circumferential environment and status of UGV.The data and control options are displayed on any phone or computer present in the Wi-Fi zones only if the user login is validated.ESP-32 microcontroller is the prime component utilized to establish reliable wireless communication between the user and UGV.These days,the demand for robot vehicles in hospitals has increased rapidly due to pandemic outbreaks as using this makes a contactless delivery of the medicinal drug.These systems are designed specifically to assist humans in the current situation where life can be at risk for healthcare facilities.In addition,the robot vehicle is suitable for many other applications like supervision,sanitization,carrying medicines and medical equipment for delivery,delivery of food and used dishes,laundry,garbage,laboratory samples,and additional supply.

Wireless recommendations for internet of vehicles:Recent advances,challenges,and opportunities

Internet of Vehicles(IoV)is a distributed network of connected cars,roadside infrastructure,wireless communication networks,and central cloud platforms.Wireless recommendations play an important role in the IoV network,for example,recommending appropriate routes,recommending driving strategies,and recommending content.In this paper,we review some of the key techniques in recommendations and discuss what are the opportunities and challenges to deploy these wireless recommendations in the IoV.

广州地铁18号线车地无线通信设备施工研究

城市轨道交通的发展,极大地缓解了城市交通运输压力。地铁无线通信设备是保证列车安全、高效运行的一种不可缺少的综合系统。早期通信设备受干扰多、安全性低,而现代地铁运能大、速度快、班次密,对车地无线通信设备性能提出了更高要求。该文以广州地铁18号线为例,探究车地无线通信设备施工要点,以期助力提升现代轨道交通建设运营水平。

5G移动通信技术在地铁车地无线通信中的应用

5G移动通信技术在地铁车地无线通信系统中的应用展现出巨大优势。基于此,文章围绕5G移动通信技术在地铁车地无线通信中的应用进行探讨,概述5G移动通信技术的基本特性,分析车地无线通信系统中应用的5G移动通信关键技术,主要包括移动边缘计算(Mobile Edge Computing,MEC)技术、毫米波通信技术、网络功能虚拟化技术、网络切片技术以及大规模输入输出(Multiple-Input Multiple-Output,MIMO)技术。结合实际案例探讨5G移动通信技术在地铁车地无线通信中的应用,结果显示,采用5G移动通信技术的地铁车地无线通信的最低传输速率超过100 Mb/s,旨在为地铁通信技术的发展及应用提供参考。

基于5G的城市轨道交通车地无线通信系统应用研究

随着通信技术不断发展,5G在各个行业中的应用愈发广泛。5G具有可靠性高、延时较低、覆盖范围广等特点,将其应用于城市轨道交通车地无线通信系统,能够更好地满足城市轨道交通车地无线通信需求。基于此,文章分析5G的优点,阐述城市轨道交通车地无线通信中的长期演进技术(Long Term Evolution,LTE)、无线局域网(Wireless Local Area Network,WLAN)技术,提出5G在城市轨道交通车地无线通信系统中的应用。通过文章研究为相关人员提供参考借鉴,以便在城市轨道交通车地无线通信系统中发挥5G的优势与价值。

城市轨道交通中车地无线通信系统的分段开通与性能测试分析

无线通信系统将文字、语音、视频等信息以信号的方式传输到终端,在城市轨道交通的通信建设中得到广泛应用。结合车地通信的传输需求,采用分段开通方式,搭建车地无线通信系统,具有较大优势。文章简要分析车地无线通信系统的功能需求,并设计车地无线通信系统的整体架构。同时,测试车地无线通信系统的综合应用能力,测试结果表明车地无线通信系统可满足城市轨道交通的业务需求,可推广及应用在实际工作中。

CBTC系统WLAN车地无线通信网络在线监测关键技术及应用

目前国内大部分城市轨道交通车地无线通信系统仍采用IEEE 802.11 b/g协议,工作在2.4 GHz ISM开放频段,车地通信故障易造成列车紧急停车等情况。针对目前车地无线通信监测完整性和实用性不足、全链条监测手段缺乏等问题,结合无线通信系统范围广、场景多、故障现象迷惑性强等特点,融合无线场强采集、数据流监听、无线图谱定位、贝叶斯网络故障等定位技术,利用软硬件结合的方式构建全链条车地无线智能分析监测系统。采用射频处理单元+运行处理单元软硬件分离的架构模式设计无线监测终端,采用C/S架构和人工智能技术设计车地无线智能分析监测系统,实现从车载到轨旁无线场强、漫游切换、多信道监测等智能分析功能。该系统已在北京地铁亦庄线、昌平线、10号线等多条线路上应用,运用效果良好,满足现场无线监测需求,大幅提升了车地无线通信监测能力及应急处置响应效率,对保障列车运营安全具有重要意义。

矿井车辆无人驾驶关键技术研究

矿井车辆无人驾驶是减少煤矿井下作业人员,建设安全、高效、绿色、智能化矿井的需要。总结了矿井车辆无人驾驶特点:煤矿井下作业人员位置全面感知、矿井车辆全部受控、矿井轨道运输设备只需一维定位、光照条件差、无线传输衰减大、无卫星信号、电磁环境复杂、电气防爆、环境潮湿、有淋水和粉尘。分析了煤矿井下超声波定位、激光定位、无线电定位(包括RFID,ZigBee,UWB,WiFi6,5G)、惯性导航、即时定位与地图构建(SLAM)、里程计等矿井车辆定位技术特点,提出了以UWB为主,惯性导航、里程计和SLAM为辅的矿井车辆联合定位方法。分析了激光雷达、毫米波雷达、红外摄像机、可见光摄像机、可见光双目视觉相机等矿井无人驾驶车辆障碍物识别与测距技术特点,提出了以激光雷达为主,毫米波雷达、红外摄像机、可见光摄像机、可见光双目视觉相机、超声波雷达为辅的矿井无人驾驶车辆障碍物识别和测距多信息融合方法。针对矿井无人驾驶车辆在遇到路况复杂,自动驾驶不能决策时,需自动转入地面远程控制模式的情况,指出基于5G无线通信系统的矿井车辆无人驾驶地面远程控制技术是首选方案,但矿用5G无线通信系统存在无线覆盖半径小、成本高等问题,可研究WiFi7在矿井车辆地面远程控制中的应用。

基于长期演进(LTE)技术的城市轨道交通车-地通信网络研究

城市轨道交通车辆与地面通信的稳定性和准确性对运营安全至关重要。将LTE(长期演进)技术与WLAN(无线局域网)技术进行比较,分析LTE用于城市轨道交通车-地通信的技术优势。通过对郑州轨道交通1号线一期工程基于LTE技术的车-地无线通信网络系统方案进行分析,并对1号线的通信网络进行实测,验证了LTE技术的可行性。

基于无线通信网络的无人机监控系统设计

随着四旋翼无人机在民用领域应用的普及,"黑飞"问题随之出现而且尤为突出。如何规范无人机有序的放飞以及对无人机的飞行过程进行有效的监管,已成为目前民用无人机领域亟待解决的一个问题。在无人机上安装机载监控模块,通过GSM/GPRS无线通信网络将无人机飞行数据传输至地面站监控计算机,可以实现对无人机的实时有效的监管。

基于无人机的红外监控系统设计

传统的红外监控系统易受干扰、误报率高、且监控范围有限。四旋翼无人机具有低成本、垂直起降、机动性好等优点,在诸多民用领域得到了广泛应用。该文将无人机平台与红外相机结合,配置相应的无线图像传输链路,与地面站组成无人机红外监控系统,能够实现机动的红外监控。无人机可以根据规划路径对重点区域进行安保监控,能够在用户操作下跟踪可疑目标。无人机与红外相机结合组成的监控系统能够克服传统红外监控方式的缺陷,提高监控的智能化水平,满足更多应用场合的需求。

无线传感器网络在美军目标部队中的应用

介绍了美军目标部队的无线传感器网络的系统组成和各部分的主要功能,以及在能源受限条件下的系统体系结构。重点探讨了无人值守地面传感器系统的层次结构和传感器节点的分类。描述了节点通信电台的功能和关键技术,并利用无线传感器网络完成一个目标探测、处理、传输形成态势感知的过程。

5G通信技术在城市轨道交通中的应用分析

本文从5G通信技术特点及5G通信技术与其他技术的对比分析,综合考虑城市轨道交通的需求分析,从5G通信技术发展趋势、技术特点和产业发展趋势进行了分析,提出了可行性建议。

CBTC车-地无线通信方案研究

基于通信的列车控制系统(CBTC)和民用WiFi设备都工作于2.4GHz频段,需要采取一定的措施来避免系统之间的干扰。针对目前存在的干扰问题,阐述各种解决方案,分析各自的优缺点,提出切实可行的措施。

运载火箭外测安全系统地面测试设备仿真训练系统

为使航天科技人员迅速掌握运载火箭外测安全系统地面检测设备的工作原理、工作过程及检测程序.针对外测安全系统在火箭飞行过程中的地位和作用,论证了基于网络模型的功能仿真设计方案和仿真训练方法.提出了运载火箭外测安全系统地面测试设备仿真训练系统实现的原则与目标,确定了系统的功能需求和软硬件环境,完成了系统框架设计.在系统软件开发环境下,充分利用网络技术和多媒体手段,对设备原理模块和工作过程仿真模块进行了论证.本训练系统能提供较为完备的交互式仿真训练手段.