5G大规模波束赋形技术综述

大规模波束赋形技术是5G新空口(NR)满足增强移动宽带(eMBB)、超高可靠低时延(URLLC)以及海量机器间通信(mMTC)三大场景性能指标的核心技术。从学术研究和产业发展两个角度回顾了大规模波束赋形技术的发展历史,探究了大规模波束赋形技术性能增益的理论源头,分析了验证和测试结果,进一步说明了理论的正确性和大规模波束赋形技术的可行性;针对大规模波束赋形的关键技术展开讨论,从信道建模、传输/接收方案、反馈方案、参考信号设计和天线阵列设计等角度分析大规模波束赋形的技术瓶颈和可能的解决方案;介绍了大规模波束赋形技术在5G NR中的标准化方案,包括传输方案、信道状态信息获取机制、参考信号设计、协作方案和波束管理等,剖析其设计机理并指出了设计上的一些缺陷。最后对大规模波束赋形技术的演进方向做了总结和展望,梳理了进一步增强的技术方向。从产学研用等多个角度解析大规模波束赋形技术的发展脉络,希望为相关研究提供有益的指导和借鉴。     

一种星载通信混合反射面天线的设计方法

为了使星载通信天线产生1个赋形波束覆盖服务区,同时产生1个固定点波束和1个有限扫描点波束,该文提出一种由2个赋形反射面和3个馈源组成的混合反射面天线。该天线是以赋形主反射面共用为基础,等效为2副单馈源单偏置反射面天线和1副双偏置格里高利型赋形反射面天线,分别产生赋形波束、固定点波束和有限扫描点波束。通过对一副口径为1.2 m的天线各个波束进行仿真实验,赋形波束在Ku收、发频段时波束覆盖区边缘(EoC)方向性系数为27.5 dBi,固定点波束在C收、发频段时天线口径效率高于70%,通过将赋形副反射面及对应馈源横向偏焦实现Ka收、发频段的点波束在服务区内外的扫描。仿真结果表明,该混合反射面天线可实现C/Ku/Ka频段的同时通信任务。     

通信卫星反射器天线的多频段馈源的设计

前言日益需要一种能够提供较大通信容量和同时具有多种功能的通信卫星,例如装有电视广播转发器的多路通信转发器。鉴于这种需要,必须有一种在多频段中可以提供赋形波束和区域复盖波束的多频段天线系统。一些通用的休斯通信卫星天线设计是由照射偏馈抛物面反射器的喇叭阵组成的,这种反射器在4/6 GHz频段中能够提供赋形波束的复盖区域。为在较高频段如12/14或20/30GHz频段中同时产生波束,那就要研制多频段馈源。     

基于非均匀特异媒质的赋形天线设计

在PCB板表面蚀刻不同尺寸的微带单元结构,构建非均匀特异媒质层,并将其放置在天线辐射单元前方,利用非均匀特异媒质层对电磁波不同的反射系数,实现对天线辐射波束的赋形。设计了由不同尺寸正方形贴片组成的非均匀特异媒质层,并放置于工作频率为5.8 GHz的矩形贴片天线前方。仿真和测试表明:该非均匀特异媒质层能够在基本保持贴片天线工作频点和回波损耗曲线不变条件下,通过调整与贴片天线距离,实现辐射波束由笔形波束向宽角波束和马鞍形波束的赋形转换。为赋形天线设计提供了一种有效的新方法。     

双馈源双偏置结构星载通信多波束天线

为了使星载通信天线产生赋形波束的同时,又能辐射具有扫描特性的点波束满足特殊情形下的通信要求,提出了一种以单馈源赋形反射面天线为基础,利用另一个馈源进行副反射面赋形,补偿主反射面口径相位差的方法,从而形成高效率点波束,并通过副反射面及对应馈源横向偏焦实现点波束扫描的目的。为了检验方法的有效性,仿真实验了一副口径为2.2 m 的赋形反射面天线。实验结果表明:赋形波束在服务区内部的最小增益是30.0dBi,点波束在服务区内部及周边区域扫描时具有比赋形波束更高的增益,因此,所提方法是有效的。     

5G波束赋形优化的典型场景立体覆盖研究

5G波束赋形技术是5G NR满足增强移动宽带(eMBB)、超高可靠低时延(uRLLC)以及大规模机器类通信(mMTC)三大场景的核心技术之一.本研究采用大规模波束赋形增益计算方法对大规模波束赋形技术的实现原理、CSI反馈机制、波束扫描和波束管理的实现机制进行分析,研究发现波束赋形技术可以对水平和垂直方向进行扫描,增加了...     

智能天线在TD-LTE中的应用分析

文章从技术层面介绍了智能天线的基础技术、波束赋形技术和自适应算法,介绍了TD-LTE中智能天线的单流波束赋形、双流波束赋形技术及相关算法,分析了智能天线在TD-LTE中的应用情况,最后简述了智能天线技术的发展态势。     

多天线技术提升TD-LTE网络性能

在无线通信领域,对多天线技术的研究由来已久,其中天线分集、波束赋形、空分复用（MIMO）等技术已在3G和LTE网络中广泛应用。改善覆盖提高速率根据不同的天线应用方式,常用的多天线技术包括天线分集、波束赋形和空分复用等,具体内容见表1。     

60GHz无线通信系统中自适应扇区波束赋形算法研究

针对60GHz无线通信系统中波束赋形算法复杂度高的缺点,提出了一种自适应扇区级波束赋形算法(Self-adaption Sector,SAS)。该算法利用已知波束码本数目,结合实际信道情况自适应地生成扇区级码本数目,进而按照IEEE802.15.3c标准重新构造扇区级和波束级码本,根据信道状态信息,通过二维曲面搜索,最终得到用于收发双方通信的最优波束对。仿真结果验证了该算法的可靠性和有效性。与现有算法相比,提出的算法能够明显降低波束搜索的复杂度,减少赋形过程中信令传输和能量损耗。     

毫米波通信中的波束管理标准化现状和发展趋势

Massive MIMO是5G系统中实现多千兆吞吐量、提升频谱效率和网络性能最有前景的技术之一。在5G新空口(New Radio,NR)系统中,采用大规模天线阵列的混合波束赋形技术已成为解决高频传播损耗、提升高频通信频谱效率的常见方法。文章根据5G NR标准化进展,对现有波束管理流程进行系统综述,介绍Rel-15和Rel-16版本下波束管理的演进过程,并结合未来5G-Advanced标准演进方向,提出针对UE多面板配置的传输增强方案,基于干扰感知和AI预测的波束管理技术以及多站点协作传输场景下TRP快速切换的波束管理流程。     

Implementation and Experimental Verification of a Smart Antenna System Operating at 60 GHz Band

With the introduction of the unlicensed spectrum at the 60 GHz range, the development of communication systems with data rates in Gb/s range has become feasible. However, there are quite significant challenges at this frequency range such as high propagation loss, oxygen absorption, antenna alignment and unavailability of high-gain, high power circuit elements. In this paper we present a novel 2-channel hybrid smart-antenna system operating at 60 GHz band which can be used with an antenna switching system to improve the signal power performance and to serve as an automated alignment system. The critical system parameters for a smart-antenna system at this frequency are the transmitter to receiver distance, element spacing, and antenna beamwidth. As the widely known beamforming assumptions may not hold for some configurations, a more general beamforming formulation is given in the paper to serve as a guideline for system designers. The twist angle of array elements is introduced as a new array design parameter. By selecting the optimal twist angle to help overlap radiation patterns, the fine alignment of the transmit and receive beams is established electronically using beamforming, thus reducing the cost of deployment and maintenance of the 60 GHz indoor communication systems.      

基于3.5GHz&2.1GHz混合组网的高铁覆盖规划研究

5G NR3.5GHz&2.1GHz的混合组网,通过高低频网络的协同,可以达到下行低频段的广覆盖或上行增强覆盖的目的。针对高铁场景高速移动、长距离连续覆盖、高穿透损耗等特征,通过3.5GHzTDD&2.1GHzFDD独立组网和协同组网的对比分析,并结合高低频组网工程建设方案、接入参数的设置分析,以探讨高低频组网在5G高铁覆盖场景的应用。     

应用于毫米波段的宽带波束调控超表面设计

毫米波段因其较高的数据传输速率和较大的容量而备受关注。为满足现代通信系统对宽带、波束偏转和高辐射效率等天线需求，本文提出了一种工作在88.5～94.6 GHz频带范围内的石墨烯-金属复合结构超表面。该超表面通过调节石墨烯的费米能级，对超表面单元的反射相位进行实时调控编码。调整金属层结构尺寸，可以调制不同编码状态下超表面单元的相位、幅度响应以及编码频段范围。经优化设计，在石墨烯费米能级分别为0 eV和1 eV时，编码超表面单元在88.5～94.6 GHz的宽频带内具有180°±20°的反射相位差，并且反射幅度均大于0.7。利用该单元设计了7×7的超表面，通过合理排布编码单元，可对毫米波段波束进行偏转和多波束切换等动态调控。实验结果显示，单波束最大偏转角度可达105°(-55°～50°),且可实现1～5个波束的切换。该超表面为多功能天线设计提供了新的解决方案，在高速无线局域网、车载雷达、卫星通信等领域具有潜在的应用价值，对毫米波段通信技术的发展具有重要意义。     

Design of a 24-40 GHz balanced low noise amplifier using Lange couplers

A wide band(24-40 GHz)fully integrated balanced low noise amplifier(LNA)using Lange couplers was designed and fabricated with a 0.15/zm pseudomorphic HEMT(pHEMT)technology.A new method to design a low-loss and high-coupling Lange coupler for wide band application in microwave frequency was also presented.This Lange coupler has a minimum loss of 0.09 dB and a maximum loss of 0.2 dB over the bandwidth from 20 to 45 GHz.The measured results show that the realized four-stage balanced LNA using this Lange coupler exhibites a noise figure(NF)of less than 2.7 dB and the maximum gain of 30 dB;moreover,a noticeably improved reflection performance is achieved.The input VSWR and the output VSWR are respectively less than 1.45 and 1.35 dB across the 24-40 GHz frequency range.     

一种用于5G移动通信的毫米波大规模天线系统

毫米波大规模天线是目前5G研究中的热点技术之一,毫米波大规模天线可提供高增益波束和大带宽,能有效提升系统能量效率和容量.面向未来5G移动通信需求,提出一种基于数字-模拟混合波束形成架构的毫米波大规模天线设计方案.采取该方案,天线内部各单机功能界限清晰、接口明确,可极大提升天线系统的可测试性和可批量生产性.基于该设计方案...     

A 9–31-GHz Subharmonic Passive Mixer in 90-nm CMOS Technology

A subharmonic down-conversion passive mixer is designed and fabricated in a 90-nm CMOS technology. It utilizes a single active device and operates in the LO source-pumped mode, i.e., the LO signal is applied to the source and the RF signal to the gate. When driven by an LO signal whose frequency is only half of the fundamental mixer, the mixer exhibits a conversion loss as low as 8–11 dB over a wide RF frequency range of 9–31GHz. This performance is superior to the mixer operating in the gate-pumped mode where the mixer shows a conversion loss of 12–15dB over an RF frequency range of 6.5–20 GHz. Moreover, this mixer can also operate with an LO signal whose frequency is only 1/3 of the fundamental one, and achieves a conversion loss of 12–15dB within an RF frequency range of 12–33 GHz. The IF signal is always extracted from the drain via a low-pass filter which supports an IF frequency range from DC to 2 GHz. These results, for the first time, demonstrate the feasibility of implementation of high-frequency wideband subharmonic passive mixers in a low-cost CMOS technology.     

超短波频谱监测网络化接收机设计

随着物联网和通信技术的迅速发展,频率资源供需矛盾日益突出。为了对电磁环境进行测试和数据采集,掌握各种无线电业务和通信系统,特别是宽带无线接入、物联网等新业务用频的背景噪声和频率使用情况,设计了一种超短波频谱监测网络化接收机。该接收机监测的频率范围为20MHz～3GHz,可提供多种IF处理带宽以适应处理不同信号的要求,具有较高的接收灵敏度和抗干扰性能,并具有最佳信噪比,能适应较宽动态范围的监测需要。     

双波段高抑制的LTCC微型双工器设计

该文设计了基于低温共烧陶瓷(LTCC)技术的双波段高抑制、低损耗的双工器。该双工器由低通滤波器和带通滤波器组成,且在低、高频段的阻带抑制方面运用了传输零点理论,在实现双工器低损耗的同时,也实现了在多波段的高抑制,提升了双工器的性能。该双工器在低频段(0.68~0.95 GHz)及高频段(1.43~2.40 GHz)时插损均小于1.2 dB,但在1.43~2.40 GHz时双工器抑制大于20 dB,0.68~0.95 GHz时双工器抑制大于15 dB。在4.9~5.9 GHz时双工器抑制大于13 dB,具有良好的市场应用前景。     

内置驱动器的六位GaAs PHEMT宽带单片数控衰减器

采用增强/耗尽型(E/D)结构的赝配高电子迁移率晶体管(PHEMT)技术,研制开发的砷化镓MMIC单片六位数字控制衰减器,具有衰减精度准确、承受功率大、线性度高等特点,并且集成了驱动器,使得输入信号控制线减少了一半,大大减少了系统布线的难度。产品由GaAsPHEMT标准工艺线加工。测试结果表明,在0.05～3.0GHz带内,插入损耗≤2.3dB@3GHz,带内输入输出驻波比≤1.5,衰减精度在±(0.3dB+3%)以内,1dB压缩功率点达到了27dBm,IP3超过了+45dBm。     

Performance Evaluation of NL-BMD Precoding over Analog-Digital Hybrid Beamforming for High SHF Wide-Band Massive MIMO in 5G

Massive multiple-input multiple-output (MIMO) technology is a key enabler in 5G. A configuration combining analog beamforming and digital MIMO signal processing for multi-beam multiplexing, i.e. analog-digital hybrid beamforming, is one of the promising approaches of massive MIMO. With the configuration, we can mitigate the problems of complexity and power consumption, which are serious in higher super high frequency and extremely high frequency bands. In this paper, we evaluate the performance of nonlinear block multi-diagonalization (NL-BMD) precoding, an intermediate solution between the conventional linear precoder (LP) and nonlinear precoder (NLP), over an analog-digital hybrid beamforming constitution. Through numerical evaluation assuming indoor hotspot scenarios, it is clarified that, NL-BMD yields up to 18.8% improvement and 5.1 dB gain in average sum-rate spectral efficiency performance, compared with block diagonalization (BD), which is one of the typical schemes of conventional LP, while reducing the complexity to 1/2 of the conventional NLP. In addition, even under a dynamic fading condition, NL-BMD shows tolerance for channel transitions and still better performance than BD: NL-BMD suppresses performance loss in sum-rate spectral efficiency due to channel transitions to 18.3%, whereas BD shows over 20% loss.