Antenna Array Structures Effect on Water-Filling Capacity of Indoor NLOS MIMO Channel

1 Introduction Digital communication using MI MO has recently e-merged as one of the most significant technical break-throughs in modern wireless communications .Foschini ,Telatar and others saythat the capacity can beincreasedlinearly with the mini mum antenna numbers of thetransmitter and receiver if the scattering environment isrich and there is no correlation between the antennapairs at the transmitter and the receiver[1 ~2]. Toachieve these capacities coding techniques such asBLAST an…     

Circularly polarized dielectric-loaded planar antenna excited bythe parallel feeding waveguide network

A new receiving planar array antenna for DBS (direct broadcasting satellite) is proposed. The element antenna is a short waveguide aperture mounted in the ground plane, loaded with a dielectric and polarizers, and excited through its side wall by another feeding rectangular waveguide. The gain of the element antenna loaded with a dielectric is so high that the grating lobes can be reduced sufficiently even if the element spacing in the array is wider than the wavelength in free space. Therefore we can reduce the number of the array elements, and parallel feeding by the low loss waveguide network can be feasible to provide a planar array antenna. This paper describes the experimental results of several kinds of the circularly polarized dielectric-loaded element antennas and the planar antennas fed by the waveguide network. In the 12 GHz band the planar antenna with 64-element radiators has a maximum gain of 31.9 dBi with an aperture efficiency of 94.7%, the 1 dB-down frequency bandwidth of the gain is about 800 MHz (6.7% for a center frequency of 11.85 GHz), and the frequency bandwidth of the axial ratio is less than 1 dB of 850 MHz (7.2%)     

Dual band rectangular patch antenna array with defected ground structure for ITS application

A dual band inset fed rectangular patch antenna array has been proposed for intelligent transportation system (ITS) application. This paper proposes 8–element patch array antenna with defected ground structure (DGS). The simulated results of 2, 4 and 8 element patch with and without DGS are also compared. Proposed antenna gets dual band of 5.02 GHz and 5.92 GHz centre frequency with DGS. The 8–element patch array antenna with DGS is fabricated and its result is compared with simulation result. 26.5 dBi and 24.9 dBi is measured gain of the proposed antenna structure for 5.02 GHz and 5.92 GHz centre frequency respectively.     

平坦衰落环境中多输入多输出系统衰落相关与信道容量研究

为分析模型物理参数和天线排列方式对多输入多输出系统信道容量的影响,提出了一种平坦衰落环境中信道容量的研究方法。该方法基于接收均匀圆阵和均匀线阵分别构建了蕴含模型物理参数的相关矩阵,并利用Wishart分布的性质推导了信道容量上下限。该方法回避了求取衰落相关矩阵特征值的概率密度函数,降低了运算量;可被推广到多天线-频分复用系统。仿真结果表明,天线间距较小时,采用均匀圆阵比均匀线阵的系统信道容量要高;天线间距增大到一定程度后,系统信道容量达到饱和。散射角越大,信道容量的增长速率越快且采用均匀线阵比均匀圆阵系统的信道容量高。接收信噪比较大时,平均信道容量上下限基本接近其实际值。     

Wideband smart antenna theory using rectangular array structures

Smart antenna techniques at the base station can dramatically improve the performance of the mobile radio system by employing spatial filtering. The design of a fully spatial signal processor using rectangular array configuration is proposed. Two-dimensional (2-D) spatial filters that can be implemented by microstrip technology are capable of filtering the received signal in the angular domain as well as the frequency domain. Furthermore, it has wideband properties and, hence, eliminates the requirement of different antenna spacing for applications including various carrier frequencies. The desired frequency selectivity of the smart antenna can be combined with compensation of the undesired frequency performance of a single antenna element, and the result is quite satisfactory for practical implementation. In addition, if the elements of the array are not perfectly omnidirectional or frequency independent, we can compensate for these deficiencies in the design algorithm. Two different algorithms for calculating the real-valued weights of the antenna elements are proposed. The first algorithm is more complex but leads to sharper beams and controlled performance. The second method is simpler but has wider beam and lower fractional bandwidth. Some computer simulation results demonstrating the directional beam patterns of the designed beamformers are also presented.     

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.     

焦面场分析与相控阵馈源设计

该文介绍了焦面场的计算方法及其与反射面焦径比的关系,分析了焦面场与馈源口径场的联系,并建立了基于焦面场分析进行相控阵馈源设计的方法,包括确定单元间距、阵列规模以及实现目标方向图所需要的激励。按照这一方法,分别以未赋形卡塞格伦天线和前馈抛物面天线为对象,设计了各自的相控阵馈源以实现赋形波束的效果,并在后者上验证了波束扫描性能。通过仿真,天线性能实现了预定目标,证明了设计方法的有效性。     

Closed‐Loop Transmit Diversity Techniques for Small Wireless Terminals and Their Performance Assessment in a Flat Fading Channel

Closed‐loop transmit diversity is considered an important technique for improving the link budget in the third generation and future wireless communication standards. This paper proposes several transmit diversity algorithms suitable for small wireless terminals and presents performance assessment in terms of average signal‐to‐noise ratio (SNR) and outage improvement, convergence, and complexity of operations. The algorithms presented herein are verified using data from measured indoor channels with variable antenna spacing and the results explained using measured radiation patterns for a two‐element array. It is shown that for a two‐element array, the best among the proposed techniques provides SNR improvement of about 3 dB in a tightly spaced array (inter‐element spacing of 0.1 wavelength at 2 GHz) typical of small wireless devices. Additionally, these techniques are shown to perform significantly better than a single antenna device in an indoor channel considering realistic values of latency and propagation errors.     

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。     

Capacity Enhancement Using MIMO Antenna Arrays in Realistic Macro-Cellular Urban Environment

In MIMO systems the antenna array configuration in the BS and MS has a large influence on the available channel capacity. In this paper, we first introduce a new Frequency Selective (FS) MIMO framework for macro-cells in a realistic urban environment. The MIMO channel is built over a previously developed directional channel model, which considers the terrain and clutter information in the cluster, line-of-sight and link loss calculations. Next, MIMO configuration characteristics are investigated in order to maximize capacity, mainly the number of antennas, inter-antenna spacing and SNR impact. Channel and capacity simulation results are presented for the city of Lisbon, Portugal, using different antenna configurations. Two power allocations schemes are considered, uniform distribution and FS spatial water-filling. The results suggest optimized MIMO configurations, considering the antenna array size limitations, specially at the MS side.     

Optimization of Antenna Array Structures in Mobile Handsets

A study of the capacity of multiple-element antenna systems is presented with particular emphasis on the effects of mutual coupling between the antenna elements. As the total size of the array is often fixed and limited, the correlation of fading as well as the mutual coupling of two elements separated in index by some value$l$increases. In this paper, at first with the assumption that the length of the linear array of antenna elements and the number of antenna elements at the receiver are fixed, the capacity with coding, without coding, and the symbol error rate (SER) of space-time coding are investigated. The results obtained show that for the mean signal to noise ratio at the receiver of$rho = 20$dB, the linear array of three antenna elements is the optimum choice if the total length of the array is in the range of$0.3lambda$–$0.86lambda$, while in the case of channel state information (CSI), this range is$0.25lambda$–$0.6lambda$. The effects of the signal-to-noise ratio (SNR) and number of the base station antenna elements on the capacity of the fixed-length linear arrays are also discussed. Next, it is assumed that the number of antenna elements at the transmitter and receiver are equal. Simulation results show the number of antenna elements for maximizing the capacity.     

通信天线信道容量机电耦合建模及阵元位置灵敏度分析

以相控阵天线为代表的下一代通信基站天线正在向着高频段、高增益、高密度、高指向精度方向发展,机械结构因素对通信系统信道质量的影响与制约越来越明显、机电耦合问题越来越突出.为有效保证复杂环境下5G/6G通信容量目标的实现,本文针对通信基站相控阵天线的机电热耦合问题,建立了融合阵元位置偏移、姿态偏转及温度分布等因素的基站天线信道容量机电耦合模型,可据此快速评估射频器件发热环境下通信指标退化情况;构建了阵列天线电场强度与信道容量对阵元随机位置误差的灵敏度模型,分析比较了不同工作条件下各阵元随机位置误差对通信指标的影响规律.     

极化对射频仿真系统阵列控制的影响

射频仿真暗室天线阵列的精度控制通常采用20世纪70年代美国波音公司提出的幅度重心公式,该表达式忽略了天线阵面弧度对三元组喇叭极化方式的影响,以及三元组天线单元间距对控制精度的影响,因此存在控制误差。该文充分考虑上述2个因素对等效目标回波方位的影响,对原三元组天线阵控制方案作了改进。由于新的控制方案充分考虑了极化、单元间距等因素对雷达目标角闪烁的影响,因此控制精度较原先有显著提高。     

Effect of feed array configuration on the Field-of-View of radio telescope antenna

Phased Array Feed (PAF) is a small two-dimensional phased array antenna, playing a role as the multi-beam feed for the reflector antenna. The prominent capability of large continuous Field-of-View (FoV) coverage and fast survey speed makes PAF the promising feed for radio telescopes. In this paper, the effect of feed array of PAF on the gain fluctuations over FoV is analyzed on a simplified model of the Five-hundred-meter Spherical Aperture radio Telescope (FAST), including illumination pattern edge taper, element spacing, element arrangement and element amount. And the differences between rectangular and hexagonal array arrangements are compared. The relationship between the FoV and array configuration are concluded at last.     

A novel wideband space‐time channel simulator based on the geometrical one‐ring model with applications in MIMO‐OFDM systems

In this paper, we extend the geometrical one‐ring multiple‐input multiple‐output (MIMO) channel model with respect to frequency selectivity. Our approach enables the design of efficient and accurate simulation models for wideband space‐time MIMO channels under isotropic scattering conditions. Two methods will be provided to compute the parameters of the simulation model. Especially, the temporal, frequency and spatial correlation properties of the proposed wideband space‐time MIMO channel simulator are studied analytically. It is shown that any given specified or measured discrete power delay profile (PDP) can be incorporated into the simulation model. The high accuracy of the simulation model is demonstrated by comparing its statistical properties with those of the underlying reference model with specified correlation properties in the time, frequency and spatial domain. As an application example of the new MIMO frequency‐selective fading channel model, we study the influence of various channel model parameters on the system performance of a space‐time coded orthogonal frequency division multiplexing (OFDM) system. For example, we investigate the influence of the antenna element spacings of the base station (BS) antenna as well as the mobile station (MS) antenna. It turns out that an increasing of the antenna element spacing at the BS side results in a higher diversity gain than an increasing of the antenna element spacing at the MS side. Furthermore, the diversity gain brought in by space‐time block coding schemes is investigated by simulation. Our results show that transmitter diversity can significantly reduce the symbol error rate (SER) of multiple antenna systems. Finally, the influence of the Doppler effect and the impact of imperfect channel state information (CSI) on the system performance is also investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

A high-gain 58-GHz box-horn array antenna with suppressed gratinglobes

A low-profile high-gain antenna array of box horns for the frequency band 57.2-58.2 GHz is presented. The antenna consists of 256 radiating elements divided into two subgroups of 128 elements fed by a rectangular waveguide feed network. The radiating elements are fed in parallel and the waveguides are connected with T-junctions. The matching of the T-junctions is improved with a matching pin and a splitter. Because of the waveguide feed network, the element spacing is larger than one wavelength, which causes grating lobes. The grating lobes and sidelobes in the H-plane have been suppressed by the use of a combination of subarrays, a special characteristic of the box horn, and an array amplitude tapering. The measured sidelobe levels in the H-plane are below -30 dB at angles larger than 8° from boresight. A gain higher than 35.7 dBi and a return loss higher than 14.4 dB have been measured for the antenna over the band 57.2-58.2 GHz     

Experimental Study on the Capacity of Compact MIMO Antennas for Portable Terminals

This paper presents the relationship between antenna structures and the performance of two kinds of compact MIMO antennas in order to find critical factors that affect the capacity of MIMO systems. The relationship between the channel capacity and some factors (antenna efficiency, mutual coupling, correlation) are analyzed based on experimental data under indoor Rayleigh fading environment. Antenna elements mounted in two different configurations (common and separated ground plane) with antenna spacing varying, were investigated at the frequency of 2.6 GHz band experimentally. The good characteristics in the case of separated ground plane show that the proposed antennas, even with small spacing, can still achieve high capacity to combat multipath fading and deliver higher data rates. It demonstrates that multiple antennas could be mounted onto small terminal devices without much loss of capacity. It is also found that mutual coupling has positive impact which could reduce channel correlation; negative effect which could degrade antenna efficiency. In the indoor multipath-rich environment, the negative effect is dominant.     

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。     

Compact triple band antenna for WLAN/ WiMAX applications

A low profile printed antenna with triple band operation is presented for simultaneous use in wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna consists of a rectangular radiating element fed asymmetrically by a 50 Omega microstrip line and a shaped trapezoidal ground plane. Rectangular horizontal strips are attached to the radiation element to form different current paths which make the antenna resonate in WLAN and WiMAX frequency bands. The antenna operates in dipole configuration outlining overall dimensions of 38 times 30 times 0.8 mm³.     

一种移动终端多天线方向图重构快速选择算法与基于滑动时间窗的加速实现

 多输入多输出(MIMO)系统中,天线选择技术可以在降低复杂度的同时,有效地提高系统的性能.但对于天线安装空间受限的小型终端,天线的数目将受到很大限制,本文结合方向图可重构技术,考虑基于线性接收机的空间复用系统,通过在已选择的发射天线上采用等功率分配等增益传输以减少反馈信息量.在此条件下,推导出空间相关衰落信道下自适应发射天线选择的统计容量公式下限,然后,在此基础上提出基于方向图重构的发射天线快速选择方法以最大化该容量值.此外,在实现中提出了一种基于滑动时间窗的梯度更新估计模型,缩短了算法所需时间.