共查询到20条相似文献，搜索用时 15 毫秒
1.
Ayman Abdulhadi Althuwayb Fazirulhisyam Hashim Jiun Terng Liew Imran Khan Jeong Woo Lee Emmanuel Ampoma Affum Abdeldjalil Ouahabi Sébastien Jacques 《计算机、材料和连续体（英文）》2021,69(1):679-694
With the rapid development of the mobile internet and the internet of things (IoT), the fifth generation (5G) mobile communication system is seeing explosive growth in data traffic. In addition, low-frequency spectrum resources are becoming increasingly scarce and there is now an urgent need to switch to higher frequency bands. Millimeter wave (mmWave) technology has several outstanding features—it is one of the most well-known 5G technologies and has the capacity to fulfil many of the requirements of future wireless networks. Importantly, it has an abundant resource spectrum, which can significantly increase the communication rate of a mobile communication system. As such, it is now considered a key technology for future mobile communications. MmWave communication technology also has a more open network architecture; it can deliver varied services and be applied in many scenarios. By contrast, traditional, all-digital precoding systems have the drawbacks of high computational complexity and higher power consumption. This paper examines the implementation of a new hybrid precoding system that significantly reduces both calculational complexity and energy consumption. The primary idea is to generate several sub-channels with equal gain by dividing the channel by the geometric mean decomposition (GMD). In this process, the objective function of the spectral efficiency is derived, then the basic tracking principle and least square (LS) techniques are deployed to design the proposed hybrid precoding. Simulation results show that the proposed algorithm significantly improves system performance and reduces computational complexity by more than 45% compared to traditional algorithms. 相似文献
2.
Abstract A two‐element microstrip antenna array controlled with active phase shifters has been fabricated and tested. The phase and amplitude of the active phase shifter output can be continuously changed by controlling the gate voltages of the dual gate FET. This array can be mounted on aircraft or missiles and be used in the direction finder or adaptive array systems. The mutual couplings between microstrip patches are also experimentally studied. It is found that the self‐impedance and resonant frequencies depend highly on the separation if the patches are separated less than 0.4 wavelength and become constant as the separation is greater than 0.5 wavelength. The effect of mutual coupling in the E‐plane is less prominent than that in the H‐plane. In array patterns synthesis, the mutual coupling can be neglected if the separation is greater than 0.5 wavelength. However, if the separation becomes smaller, the mutual coupling must be considered such that the calculated patterns are in good agreement with the experimental results. 相似文献
3.
为了保证相控阵雷达的性能,它的天线现场校准越来越受到重视。本文首先介绍相控阵雷达天线现场校准的现状, 提出目前存在的问题。然后分析光学电磁场探测技术优势,阐述基于光子技术的相控阵雷达天线现场校准实现的可行性,建立了现场校准装置。通过实验验证,该技术能实现对相控阵雷达天线现场校准,具有高精度,对天线的辐射场的影响较小,能满足相控阵雷达天线现场校准要求。 相似文献
4.
Directional modulation is one of the hot topics in data security researches. To fulfill the requirements of communication security in wireless environment with multiple paths, this study takes into account the factors of reflections and antenna radiation pattern for directional modulation. Unlike other previous works, a novel multiple-reflection model, which is more realistic and complex than simplified two-ray reflection models, is proposed based on two reflectors. Another focus is a quantum genetic algorithm applied to optimize antenna excitation in a phased directional modulation antenna array. The quantum approach has strengths in convergence speed and the globe searching ability for the complicated model with the large-size antenna array and multiple paths. From this, a phased directional modulation transmission system can be optimized as regardscommunication safety and improve performance based on the constraint of the pattern of the antenna array. Our work can spur applications of the quantum evolutionary algorithm in directional modulation technology, which is also studied. 相似文献
5.
根据自适应天线阵列理论，结合给定的参考波束的误差，引入虚拟干扰的概念，对目标波束图形状进行调整，提出一种新的可以应用于任意类型天线阵列的波束综舍算法．应用提出的新算法，在主辩和旁瓣位置都可以对波束进行有效的调节．最终获得阵列的最优权矢量，能够最小化目标波束图与参考波束图间的差异．理论分析与仿真结果表明，与现有的同类算法相比，该算法能更有效地获得与参考波束基本相符的波束．应用于OFDM智能天线系统时，对不同子载波频率上信号进行单独处理，利用该算法进行波束综合，能够在整个有效频段，使所有子载波上获得基本一致的阵列输出． 相似文献
6.
7.
给出了既有双稳态特性又具有天线功能的多功能复合材料层板设计与分析方法。基于非线性层板理论和Rayleigh-Ritz法,建立了双稳态混杂层板构型预报理论模型,并通过有限元计算和实验进行了验证。研究了薄膜天线混杂非对称双稳态复合材料层板的临界载荷及电磁性能,分析了铺层方式对双稳态混杂层板稳定构型、临界载荷和电磁性能的影响。结果表明：双稳态混杂层板通过转变其稳定构型实现天线主辐射方向在俯仰面内偏转30°,实现方向图可重构,扩大天线波束的扫描范围。铺层方式对层板构型和反射系数影响较大,当天线辐射层铺设在层板表面且聚酰亚胺薄膜厚度大于0.2 mm时,其双稳态特性消失,没有出现分叉现象,且其中心频率会左移大约0.2 GHz。 相似文献
8.
针对星载DBF有源相控阵天线发射波束赋形的实际需要,提出了一种基于有限幅度加权的波束赋形方案。采用双重编码遗传算法实现了该方案。分别采用有限位长度的二进制编码和实数编码对阵列加权矢量的幅度和相位进行编码,使得阵列加权矢量的幅度仅在几个离散的台阶上变化,限制了阵列加权矢量幅度的动态范围,该方案在方向图旁瓣和功率放大器的效率之间取得了折衷,更适合于实际应用。与复数编码遗传算法相比,在保持最优解的精确度的同时,由于幅度维上搜索空间的减小,加快了算法的收敛速度。为了进一步提高算法收敛速度和避免算法“早熟” ,提出了一种基于”物种多样性“选择保留策略,并对算法采用了自适应交叉和变异概率,使算法更有把握得到全局最优或准最优解。 相似文献
9.
提出了一种新型的小型化频率可重构天线,通过两个开关二极管控制天线的频率,实现频率的重构.天线结构新颖简单,采用宽缝隙天线上加载开关,且开关易于操作控制.当开关闭合时,天线的实测结果谐振频率在5.34 GHz,反射系数为-23.4 dB,相对带宽为70%,实现了超宽带.当开关断开时,天线的实测结果谐振频率为2.4 GHz... 相似文献
10.
11.
12.
13.
一种新型可重构5R机构的运动学分析 总被引：3，自引：3，他引：0
目的提出一种新型可重构5R机构,改变5R机构机架的尺寸和位置,提高基于5R机构设计的折箱设备和对不同加工作业的适应性。方法使用螺旋副提供驱动而改变定平台的位置和等效尺寸,从而实现机构的重构,得到一种新型的5R并联机构。使用旋量理论对此机构进行速度分析。结果得到了这种新型5R机构的输入-输出速度关系表达式,使用矢量法和旋量工具,进行了对比验证,两者结果一致。结论旋量理论在进行速度分析时,物理意义明确,求解模式统一,使用方便。通过对此新型并联机构进行运动学分析,可为该机构的优化设计、尺度综合、动力学分析提供理论基础。 相似文献
14.
超声相控阵系统的数据传输速率很大程度上决定着其检测速度,因而在PCI总线的超声相控阵系统中,PCI驱动执行效率至关重要。详细阐述了利用Win Driver、Driver Studio和WDK(Windows Driver Kit)三种工具开发PCI驱动程序的方法及实现。在驱动效率和兼容性等方面上比较这三种不同的驱动开发方案。分析及测试结果表明,使用Driver Studio开发的驱动能够高速稳定地工作,满足超声相控阵系统对于数据传输速率和稳定性的要求。由于不同的应用有着不同的开发需求,提出根据特定的开发需求选择不同的开发方案,从而得到需要的驱动及其应用程序。 相似文献
15.
Shakir Ullah Sadiq Ullah Inzamam Ahmad Wasi Ur Rehman Khan Toufeeq Ahmad Usman Habib Mahmoud A. Albreem Mohammed H. Alsharif Peerapong Uthansakul 《计算机、材料和连续体（英文）》2021,68(3):3015-3031
In this paper, the design and experimental evaluation of a hexagonal-shaped coplanar waveguide (CPW)-feed frequency reconfigurable antenna is presented using flame retardant (FR)-4 substrate with size of 37 × 35 × 1.6 mm3. The antenna is made tunable to three different modes through the status of two pin diodes to operate in four distinct frequency bands, i.e., 2.45 GHz wireless fidelity (Wi-Fi) in MODE 1, 3.3 GHz (5G sub-6 GHz band) in MODE 2, 2.1 GHz (3G Long Term Evolution (LTE)-advanced) and 3.50 GHz Worldwide Interoperability for Microwave Access (WiMAX) in MODE 3. The optimization through simulation modeling shows that the proposed antenna can provide adequate gain (1.44~2.2 dB), sufficient bandwidth (200~920 MHz) and high radiation efficiency (80%~95%) in the four resonating frequency bands. Voltage standing wave ratio (VSWR) < 1.5 is achieved for all bands with properly matched characteristics of the antenna. To validate the simulation results, fabrication of the proposed optimized design is performed, and experimental analysis is found to be in a considerable amount of agreement. Due to its reasonably small size and support of multiple frequency bands operation, the proposed antenna can support portable devices for handheld 5G and Wireless LAN (WLAN) applications. 相似文献
16.
随着5G/F5G时代的到来,技术赋能艺术,5G与F5G技术天地联网,双剑合璧,形成功能特点相互优化补充的态势.电影作为现代科技与艺术的综合体,技术层面的升级推动电影产业不断进步.本文通过对5G/F5G技术概念特点的阐述,梳理分析5G/F5G技术在电影摄制、发行和放映等全产业链的运用以及对于各个环节产生的影响,认为5G/... 相似文献
17.
介绍了一种适用于时分双工蜂窝移动系统,基于非线性判决反馈均衡器和递归最小平方算法的环形自适应阵列天线,研究了阵列波束对期望信号的增强和对干扰信号的抵消的形成过程,并分析了方向增益的收敛属性与训练序列的关系,计算机仿真结果表明了波束形成与接收信号到达角度之间的联系,发现了波束收敛所需训练序列的最佳长度。 相似文献
18.
19.
Wasi Ur Rehman Khan Muhammad Fawad Khan Muhammad Irfan Sadiq Ullah Naveed Mufti Usman Ali Rizwan Ullah Fazal Muhammad Saifur Rahman Faisal Althobiani Mohammed Alshareef Mohammad E. Gommosani 《计算机、材料和连续体（英文）》2023,74(2):2517-2530
A compact, reconfigurable antenna supporting multiple wireless services with a minimum number of switches is found lacking in literature and the same became the focus and outcome of this work. It was achieved by designing a Th-Shaped frequency reconfigurable multi-band microstrip planar antenna, based on use of a single switch within the radiating structure of the antenna. Three frequency bands (i.e., 2007–2501 MHz, 3660–3983 MHz and 9341–1046 MHz) can be operated with the switch in the ON switch state. In the OFF state of the switch, the antenna operates within the 2577–3280 MHz and 9379–1033 MHz Bands. The proposed antenna shows an acceptable input impedance match with Voltage Standing Wave Ratio (VSWR) less than 1.2. The peak radiation efficiency of the antenna is 82%. A reasonable gain is obtained from 1.22 to 3.31 dB within the operating bands is achieved. The proposed antenna supports Universal Mobile Telecommunication System (UMTS)-1920 to 2170 MHz, Worldwide Interoperability and Microwave Access (WiMAX)/Wireless Broadband/(Long Term Evolution) LTE2500–2500 to 2690 MHz, Fifth Generation (5G)-2500/3500 MHz, Wireless Fidelity (Wi-Fi)/ Bluetooth-2400 to 2480 MHz, and Satellite communication applications in X-Band-8000 to 12000 MHz. The overall planar dimension of the proposed antenna is 40 × 20 mm2. The antenna was designed, along with the parametric study, using Electromagnetic (EM) simulation tool. The antenna prototype is fabricated for experimental validation with the simulated results. The proposed antenna is low profile, tunable, lightweight, cheap to fabricate and highly efficient and hence is deemed suitable for use in modern wireless communication electronic devices. 相似文献