天线间隔对室内非视距MIMO信道容量的影响

采用2维射线跟踪法分析了天线间隔对非视距室内环境中MIMO系统容量ccdfs的影响。结果表明，天线间隔对MIMO系统容量影响非常显著，而且天线数目不同，天线间隔对MIMO系统容量影响不同。天线间隔越大，系统容量越接近Telatar所预测的MIMO系统容量；但随着天线间隔的减小，系统容量则会显著降低。对于相同天线间隔的多天线系统，随着天线数目的增加，系统所能实现的独立同分布瑞利信道容量的百分比越低。     

互耦效应对超大规模MIMO天线系统信道容量的影响

超大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)天线系统是6G的关键技术,由于天线单元间距很小,多个天线单元的互耦效应是影响其性能的因素之一。建立了基于石墨烯基贴片天线阵列-子阵列架构的超大规模MIMO天线系统,推导出了互耦效应影响下的信道容量表达式。通过电磁场数值计算仿真了超大规模MIMO天线系统的信道容量,结果表明,在不考虑互耦效应时,超大规模MIMO天线系统的信道容量与子阵列天线单元数、子阵列数以及发射机功率正相关;在互耦效应的影响下,系统的信道容量降低,互耦效应的强弱与子阵列天线单元的间距有关,天线单元间间距越小,相邻天线间的互耦效应越明显,系统的信道容量越小。该仿真结果可以为6G中超大规模MIMO天线系统的设计提供参考。     

DWT-based joint antenna selection for correlated MIMO channels

This paper proposes a new discrete wavelet transform (DWT)-based joint antenna selection scheme for spatially correlated multiple-input multiple output (MIMO) channels. To reduce the severe performance degradation of the traditional antenna selection schemes in correlated channels, a new scheme which employ joint antenna selection (JAS) at both link ends algorithm and embed DWT operations in the receiver-end RF chains is proposed. Through extensive simulations it is demonstrated that the proposed DWT-based joint antenna selection has significant improvement of the capacity for both i.i.d and correlated MIMO channels, while requiring only a minor hardware overhead and low computational complexity for the DWT operations. Moreover, it is shown that the capacity associated with DWT-based JAS is higher than the system employing DWT-based receive antenna selection (RAS) only. This is achieved in i.i.d. and correlated MIMO channels.     

天线阵结构对非视距室内MIMO信道容量的影响

采用2维射线跟踪法分析了非视距室内环境中天线间隔、天线阵形对MIMO系统容量和互补累积分布函数(CCDF)的影响。结果表明随着天线间隔减小,MIMO系统容量降低。10%中断容量表明,天线间隔相同时,有独立同分布瑞利信道容量大于线性阵容量大于方阵容量或者圆形阵容量的关系。当天线间隔大于等于3 时,不同天线阵列阵形对容量影响非常小,此时i.i.d.瑞利信道理论容量几乎全部实现。当天线间隔小于等于1 时,天线阵列阵形对容量影响较大,矩形阵和圆形阵MIMO系统容量相差较小,但都显著小于线性阵列系统容量。在非视距的室内环境中,要实现最大的MIMO容量增益,设计天线阵列时应该对天线间隔和阵列阵形综合考虑。     

基于MIMO系统的天线选择

多天线MIMO（Multiple Input Multiple Output）系统利用多个收、发天线有效地改善无线通信系统性能，提高系统容量，增强系统可靠性。然而，由于使用多天线同时收发，这要求发射机和接收机使用与天线一样多的射频链路，增加了系统成本和复杂度。使用天线选择技术可以降低系统成本和复杂度，同时保留MIMO系统的优越性能。文中首先介绍了MIMO系统的实现方式，然后讨论天线选择的方法及性能，最后提出天线选择技术还存在的问题，并得出相关的结论。     

大规模MIMO系统中收发联合阈值天线选择算法

在大规模多输入多输出(massive MIMO)系统中使用天线选择算法可提高能效和系统吞吐量,然而适用于传统MIMO系统的天线选择算法具有高复杂度,很难用于massive MIMO系统。为优化天线选择算法,以算法复杂度和系统容量为优化目标,提出了收发联合阈值天线选择算法。该算法在发射端使用最大范数双向天线选择算法进行天线选择,在接收端使用分组maxvol算法并通过仿真实验结果的预设阈值进行天线选择。仿真实验表明,收发联合阈值天线选择算法在降低复杂度的同时可以提高系统容量,与递增天线选择算法相比,系统容量最多可提高52.2 bit/s/Hz。提出的天线选择算法可以满足不同天线相关度和信噪比的传输环境。     

空间相关MIMO信道天线选择系统闭合容量式

在空间瑞利相关信道下,笔者推导了混合选择/多输入多输出系统(H-S/MIMO)信道容量的精确表达式。以2发送天线和2/3接收天线的MIMO系统为模型,使用MATLAB对该系统进行了仿真。结果表明,理论分析与仿真曲线相吻合,进一步说明文中理论分析的正确性。     

一种用于5G 移动通信终端的双频MIMO天线系统

为满足5G 移动通信系统对信道容量的要求,提出了一种应用于5G 移动终端的双频多输入多输出(MIMO)天线系统。它由沿移动终端两个长边垂直放置的八个天线单元组成。该天线系统可以覆盖中国工业和信息化部(MIIT)所规划的3.3 ~ 3.6 GHz 和4.8 ~ 5 GHz 两个频段,且低频段和高频段的天线效率分别高于61% 和50%。通过优化各天线的相对位置和放置方向,使得各端口之间的隔离度优于15 dB。为更好评估天线系统性能,计算了MIMO天线的包络相关系数(ECC)和信道容量(CC)。所得该MIMO 天线系统在工作频段内ECC均小于0.1,且信道容量峰值可以达到36.8 bps/ Hz。同时,制作并测量了MIMO 天线样品,测试结果与仿真结果表现出良好的一致性。     

一种用于MIMO系统的快速天线选择算法

在多径衰落环境中, MIMO系统的信道容量随天线数的增加呈线性增加,发射/接收天线选择方法能以很小的性能损失换取射频成本的大幅度降低,使MIMO系统不完全受射频成本的限制。为快速选择出使系统容量最优的发射/接收天线子集,该文提出一种快速天线选择算法的改进算法。该算法通过实时更新优化参数,大大降低计算复杂度。仿真结果表明,该算法在不影响系统容量的情况下大大减少了计算时间。     

一种应用于无线通信系统的MIMO天线

MIMO系统是通过不同的分集技术,以实现在相同带宽和发射功率的条件下大幅改善系统容量和可靠性,减小信道失真。作为系统关键模块之一的天线,则要求有着好的分集特性,并接收较多的这波。这里提出的MIMO天线工作在2．4GHz,天线单元是等边三角形贴片天线。三角形天线的宽波瓣可以使MIMO天线接收更丰富的多径这波,与天线单元的高增益相结合能较好改善MIMO系统的SNR和抗干扰能力。通过对天线端口间的互耦和相关性分析,该系统能实现好的极化和方向图分集,获得高的分集增益。     

Reconfigurable antenna solution for MIMO-OFDM systems

A reconfigurable microstrip dipole antenna solution for multiple-input multiple-output (MIMO) communication systems making use of orthogonal frequency division multiplexing (OFDM) is presented. When applied to closely spaced antenna arrays, this method can increase link capacity. The benefits of this novel antenna solution are demonstrated by channel capacity measurements taken in an indoor environment with a 2/spl times/2 MIMO system.     

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...     

一种提高微带MIMO 天线端口隔离度的新方法

多输入多输出(MIMO) 无线通信系统已经成为提高通信系统可靠性和数据传输速率的有效技术。MIMO 通信系统中,终端天线的性能对系统通信容量的提升至关重要。为了提高天线端口隔离度,提出了一种在微带天线辐射贴片上加载缝隙阵列实现天线极化分集,提高天线隔离度的方法,并且将这种方法应用于两个2 单元微带MIMO 天线设计中,取得了良好的效果。缝隙阵列加载不但抑制了微带MIMO 天线单元间的耦合,而且产生了更多谐振频点,改善了高频谐振频点畸变的天线辐射方向图,并且天线尺寸也得到了很大的减缩。最后对比分析了设计的两个微带MIMO 天线,实测结果与仿真计算比较可知,在工作带宽内,单元天线间耦合得到了非常有效的抑制。这种在平面天线辐射贴片加载缝隙阵列改变天线极化方向的技术可以很好地用来抑制多天线系统中单元天线间的耦合,而且对天线的其他性能不会造成影响。     

微小区环境下MIMO系统相关性的测量分析

多输入多输出（MIMO）技术应用于移动通信系统中可以提高频谱利用率,增加通信系统的容量．提高用户传输速率,因此,该技术已经成为后3G的关键技术之一。其信道容量不仅和通信环境有关。而且和阵元间信道响应的相关系数有很大的关系。为了对设计的MIMO系统进行评估,则需对其性能进行测试。提出了根据测试相关系数,间接得出信道传输矩阵H的方法。并在实验室环境下,以多天线系统为例。通过采集试验数据。对相关系数做了分析计算。     

MIMO系统容量的仿真分析

MIMO系统可以在不增加带宽的情况下成倍地提高通信系统的容量和频谱利用率,是新一代移动通信系统的关键技术。在简要介绍MIMO系统的工作原理及容量公式后,对不同信噪比、不同发射、接收天线数目情况下的系统容量进行了仿真分析。     

Dynamics of spatial correlation and implications on MIMO systems

The use of multiple antennas has found various applications in the area of wireless communications. One such application has recently become very popular and is referred to as the multiple-input multiple-output (MIMO) antenna system. The main idea behind MIMO is to establish independent parallel channels between multiple transmit and receive antennas. Each channel uses the same frequency, and the transmissions occur simultaneously. In such a configuration, the amount of data transmitted increases linearly with the number of parallel channels, which is what makes MIMO so popular in the wireless world. The enormous capacity offered by MIMO systems is not realizable when the parallel channels are highly correlated. The goal of this article is to highlight the correlation concept and its impact on MIMO systems. Although correlation can be defined in many dimensions, here we focus on spatial correlation, and specifically consider antenna correlations in mobile units. We provide an overview of spatial correlation and present its underlying parameters in detail. Special attention is given to mutual coupling since it has signal decorrelation and antenna gain reduction effects. We then present how correlation in a MIMO system affects the amount of data that can be transmitted (MIMO capacity) and briefly review how power should be distributed with the knowledge of correlation. Analyses indicate that in real propagation environments, the high capacity gain of MIMO systems can be realized with improved antenna selection algorithms and power allocation strategies.     

MIMO无线传输技术综述

MIMO无线传输技术是通信领域的一项重要技术突破,它能在不增加带宽与功率的情况下成倍地提高无线通信系统的容量和频谱效率,堪称新一代无线通信系统中的关键技术之一,近年来引起了人们的广泛关注与研究兴趣。回顾无线移动通信的发展历程,概述天线分集技术与智能天线技术,剖析MIMO无线传输技术的原理与国内外研究现状:传统单天线系统向多天线系统演进、智能天线向多天线系统演进、MIMO无线传输技术的原理、MIMO系统中的分集与复用、MIMO无线信道建模、MIMO系统中的多天线设计等,为深入认识与进一步研究MIMO无线传输技术奠定基础。     

Body-Worn Distributed MIMO System

In this paper, we analyze the performance of novel wearable multiple-input-multiple-output (MIMO) systems, which consist of multiple electrotextile wearable antennas distributed at different locations on human clothing. For wearable applications, a semidirectional radiation pattern of the wearable patch antenna is preferred over an omnidirectional radiation of conventional dipole antennas to avoid unnecessary radiation exposure to the human body and radiation losses. Additionally, the spatial distribution of the antennas is not constrained as a typical handheld unit. Through theoretical modeling and simulation, the wearable MIMO system is shown to demonstrate a significantly higher channel capacity than a conventional system on a handheld platform (e.g., a compact dipole array or a single dipole), due to enhanced spatial diversity and antenna pattern diversity. The unique effects of antenna directivity and location on the MIMO system capacity are investigated in terms of antenna correlation and effective gain under different wireless channel models. The advantage of a wearable system over a conventional system was further confirmed by detailed physical modeling through the combination of full-wave electromagnetic and ray-tracing simulations. Finally, complex channel response matrices were measured to characterize the performance of a body-worn MIMO system in comparison with a reference full-size dipole antenna. The 319% improvement in 10% outage capacity for the body-worn system over the reference system made of a full-size dipole antenna is consistent with the 288% improvement projected by theoretical modeling and the average 300% improvement found in the physical simulation of two typical indoor scenarios.     

Mutual coupling in multi-element array antennas and its influence on MIMO channel capacity

The effects of mutual coupling between receive elements in a multi-element antenna on multiple-input multiple-output (MIMO) system capacity are reported. The results are based upon analysis of mutual coupling calculated for a measured linear array of five printed dipole elements with 0.56 of a wavelength spacing. It is shown that the presence of mutual coupling at the receive array antenna leads to additional correlation between spatial channels and results in a loss of MIMO system capacity.     

3×3多天线系统衰落相关与信道容量研究

为分析天线间距和散射角等信道物理参数对多输入多输出系统信道容量的影响,提出了一种相关衰落环境中信道容量的分析方法。该方法基于接收均匀圆阵构建了蕴含信道物理参数的衰落相关矩阵。并由此详细推导了3×3多天线系统信道容量的闭式表达。结果表明,相关矩阵特征值的个数和大小决定了系统信道容量的大小。该方法回避了已有算法需求取相关衰落信道特征值概率密度函数的问题,降低了运算量,可以被推广到任意收发天线数的多输入多输出和多输入多输出-频分复用系统。仿真结果表明,天线间距增大,信道容量随之增大。但是当天线间距增大到衰落相关的第一个过零点时,信道容量达到最大值,再增大天线间距对信道容量影响很小。散射角越大,信道容量收敛到最大值速率越快。