Optimal Planar Array Architecture for Full‐Dimensional Multi‐user Multiple‐Input Multiple‐Output with Elevation Modeling

Research interest in three‐dimensional multiple‐input multiple‐output (3D‐MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user‐specific elevation beamforming and cell‐splitting. To evaluate the full performance benefits of 3D and full‐dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D‐SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD‐MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.     

A Survey on Hybrid, 3D,Interference Mitigation and Secure Data Beamforming Techniques for 5G System

By 2020 world will testimony new archaic Multi-antenna technologies like beamforming along with massive multiple-input multiple-output in 5G system. The cellular networks with 5th Generation (5G) are introduced with the determined aim of supporting a very heterogeneous service mixture, everyone with its individual detailed requirements. It largely leverages a very huge count of independently controllable antennas at the BS, and thereby attains greater enhancement regarding the energy and spectral efficiency. This paper elucidate about the Hybrid Beamforming techniques, 3D beamforming techniques, Interference mitigation between small and macro cell beamforming proficiency and secure data transmission pre-owned in beamforming technologies dispense a comprehensive analysis of all aspect of Beamforming technologies used in 5G systems.

     

Effects of Quantization in Systolic 2D IIR Beam Filters on UWB Wireless Communications

Ultra-wideband (UWB) wireless beamforming systems may potentially be implemented digitally at multi-gigahertz clock frequencies using low-precision systolic array realizations of two-dimensional (2D) infinite impulse response (IIR) beam plane-wave filters. The finite precision performance of such filters is analyzed in terms of quantization noise. Extensive Monte Carlo simulations are performed using test vectors that are derived from 2D finite-difference time-domain (FDTD) computational electromagnetic models of the UWB channels. The bit error rate (BER) is determined as a function of signal-to-interference ratio (SIR), with and without beamforming, and for various practical combinations of finite internal wordlengths and A/D converter precisions. It is established that 3-bit A/D converters with 3- to 6-bit internal wordlengths are adequate for good performance and that 4-bit A/D converters with 4- to 7-bit internal wordlengths achieve excellent performance.     

Diversity gain for cdma systems equipped with antenna arrays

If the angular spread is not zero, the diversity gain can be achieved in the antenna-array reception. In order to achieve the diversity gain, we propose a beamforming method that utilizes two beamforming weight vectors and apply this beamforming technique to code-division multiple-access (CDMA) systems equipped with antenna arrays under a time-varying multipath-fading channel environment. In the proposed beamforming method, the channel vector has been estimated using two basis vectors that span the signal subspace. Since the proposed beamforming method utilizes two-dimensional (2D) signal subspace, it provides better performance than the conventional beamforming method, which utilizes one-dimensional signal subspace. Through simulation results, we can see that the performance is improved as the angular spread gets larger.     

共轭梯度自适应波束形成算法

本文讨论了共轭梯度算法在自适应波束形成中的应用,指出在时域和空域同时处理,与仅在时域或空域处理的方法相比,不仅在性能上得到了改进,而且放宽了对阵元数目的要求。同时提出了一种前后向平均和多层前后向处理的结构和方法,使算法在性能上得到了进一步的改善。     

Joint Transmit Beamforming and Power Control for CDMA System

1　Introduction　Power control and beamforming are two main methods toreduce interference in CDMA cellular communication sys tem. In power control, the transmitters powers are constant ly adjusted when the instantaneous SIR is not equal to targetSIR, so that the quality of weak links is improved. Base sta tion equipped with antenna arrays may adjust their beam pat terns so that they have maximum gain towards the directionsof target mobiles and minimum gain towards the other direc tio…     

A novel adaptive beamforming algorithm for antenna array CDMA systems with strong interferers

Blind beamforming based on the maximum signal-to-noise ratio (MSNR) can improve the performance of an array system only when the processing gain of the given code-division multiple-access (CDMA) system is high enough such that the desired signal can become dominant after despreading (see Choi, S. and Shim, D., IEEE Trans. Veh. Technol., vol.49, p.1793-1806, 2000; Choi, S. and Yun, D., IEEE Trans. Antennas Propagat., vol.45, p.1393-1404, 1997). We consider a maximum signal-to-interference-plus-noise ratio (MSINR) beamforming. The MSINR performance criterion is chosen to deal with strong interferers effectively. It is shown that blind MSINR beamforming is possible by directly utilizing the input and output signals of correlators of the CDMA systems. In addition, we propose an adaptive beamforming algorithm at a lower computational complexity - about O(7.5N) - where N is the number of antenna elements of the array system. Simulation results are presented in various signal environments to show the performance of the proposed adaptive algorithm.     

Distributed Downlink Beamforming With Cooperative Base Stations

In this paper, we consider multicell processing on the downlink of a cellular network to accomplish “macrodiversity” transmit beamforming. The particular downlink beamformer structure we consider allows a recasting of the downlink beamforming problem as a virtual linear mean square error (LMMSE) estimation problem. We exploit the structure of the channel and develop distributed beamforming algorithms using local message passing between neighboring base stations. For 1-D networks, we use the Kalman smoothing framework to obtain a forward–backward beamforming algorithm. We also propose a limited extent version of this algorithm that shows that the delay need not grow with the size of the network in practice. For 2-D cellular networks, we remodel the network as a factor graph and present a distributed beamforming algorithm based on the sum–product algorithm. Despite the presence of loops in the factor graph, the algorithm produces optimal results if convergence occurs.      

TD-LTE双流波束赋形技术分析

文章介绍了3GPP Release 9中提出的双流波束赋形技术,对双流波束赋形技术的实现原理以及两种不同的应用场景进行了阐述。通过仿真,文章对单用户双流波束赋形时TM8与TM3和TM7进行了性能对比,并对单用户双流波束赋形和多用户双流波束赋形下的小区吞吐量增益进行了比较分析,分别给出了它们的信噪比适用门限。最后,文章通过外场测试评估,对仿真结果进行了验证,并给出双流波束赋形技术对系统吞吐量增益的结论。     

Radar-Based Breast Cancer Detection Using a Hemispherical Antenna Array—Experimental Results

In this contribution, an ultrawideband (UWB) microwave system for breast cancer detection is presented. The system is based on a novel hemispherical real-aperture antenna array, which is employed in a multi-static radar-based detection system. The array consists of 16 UWB aperture-coupled stacked-patch antennas located on a section of a hemisphere. The radar system is designed to be used with realistic three-dimensional (3D) breast phantoms, which have been developed, as well as with real breast cancer patients during initial clinical trials. Images are formed using two different beamforming algorithms and the performance of these algorithms is firstly compared through numerical simulation. Experimental results for the same beamforming techniques are then presented, demonstrating the successful detection of 4 and 6 mm diameter spherical tumors in the curved breast phantom.      

Adaptive Complex-Coefficient 2D FIR Trapezoidal Filters for Broadband Beamforming in Cognitive Radio Systems

A novel design method is proposed for an adaptive discrete-domain beamformer for the beamforming of temporally broadband-bandpass signals in cognitive radio (CR) systems. The method is based on a complex-coefficient 2D finite impulse response (FIR) filter having a trapezoidal-shaped passband. The temporally broadband-bandpass signals are received by a 1D uniformly distributed antenna array (1D UDAA), where the outputs of the antennas are complex-quadrature sampled by the front end of the CR system. This CR system is based on a software defined radio (SDR) architecture and can be instantly reconfigured by the control system to select the appropriate frequency band and the required sampling rate. The subsequent beamforming enhances the spectral components of the desired temporally broadband-bandpass signals by arranging for the asymmetric trapezoidal-shaped passband of the 2D filter transfer function to closely enclose the region of support (ROS) of the spectrum of the desired signal, whereas the ROSs of the spectral components of the interfering signals are enclosed by the stopband. The proposed novel closed-form design method facilitates instant adaptation of the shape and orientation of the passband of the beamforming 2D FIR trapezoidal filter in order to match the time-varying frequency band and the time-varying bandwidth of the signal, as well as to track and enhance received signals with time-varying directions of arrival (DOAs). Simulated results confirm that, compared with previously reported methods, the proposed method achieves the best overall tradeoff with respect to the instantaneous adaptations of the operating frequency band, the bandwidth, and the time-varying DOAs, the distortion of the desired passband signal, and the stopband attenuation of interfering signals.     

A 2D adaptive beamforming method in sparse array

This study presents an Accelerated Proximal Gradient singular value thresholding based Linearly Constrained Singular Canceler (APG-LCSC) algorithm to improve the performance of two-dimensional (2D) adaptive beamforming in sparse array. Firstly, a signal model is established based on Matrix Completion (MC), which can be proved to meet Null Space Property (NSP). Subsequently, left and right singular value vector of the received signal matrix is achieved via MC, and then a linearly constrained singular canceler is obtained by employing the singular value vector. The proposed algorithm decreases the required number of antennas, lowers the computational complexity and has a robust performance. Computer simulations demonstrate that the proposed APG-LCSC algorithm can acquire high accuracy of 2D beamforming in sparse array.     

3D MIMO多小区多用户系统基于QBFO 算法的垂直波束下倾角优化

本文针对大尺度衰落下3D MIMO多用户系统中天线下倾角优化问题,首先在采用最大比传输预编码的基础上,假设有用信号功率、用户间干扰功率、小区间干扰功率都服从伽玛分布,将系统和速率公式简化为关于波束下倾角的函数。然后,以系统和速率最大化为目标函数,利用改进的量子菌群觅食优化算法（quantum bacterial foraging algorithm）,求解最优的天线下倾角。计算机仿真表明,本文提出的3D波束赋形方案在低信噪比和用户数较多时可以获得更高的系统和速率。      

Two dimension angle of arrival-based precoding for pilot contamination reduction in multi-cell massive MIMO systems

Wireless Networks - This paper proposes a new precoding approach that utilizes two-dimension (2D) Angle of Arrival (AOA) based precoding (beamforming) approach for multi-cell massive Multiple Input...     

LTE中双流波束赋型的标准化进展

双流波束赋形是3GPP RAN1 R9的工作项目,目的是将LTE R8中的单流波束赋形扩展到双流,要求所有增强的能力在网络侧和终端侧均后向兼容R8。介绍了双流波束赋形的标准进展,并简要分析了相关的问题。     

2D space–time wave-digital multi-fan filter banks for signals consisting of multiple plane waves

Two dimensional space–time fan filters may be used for the highly-selective enhancement of spatio-temporal plane-waves on the basis of their directions of arrival. Unlike uniform bandwidth beam filters, ideal fan filters transmit passband signals over a range of directions of arrival that is independent of their 1D temporal spectrum. In this work, closed-form 2D wave-digital filter design equations and corresponding hardware architectures are proposed for realizing M independent fan-shaped passbands having independently steerable directionality and selectivity. A design method based on LCR ladder networks is proposed and implemented using a 2D time-multiplexed raster-scanned architecture that is suitable for low frequency applications such as audio, multimedia, seismic and ultrasonic beamforming. The architectures are designed, simulated, physically realized and tested on FPGA-based prototypes. Examples of 2D IIR M-fan filterbanks with FPGA implementations, together with measured results from on-chip hardware verifications, show the successful design and hardware realization. The filterbanks and hardware architectures are shown to be suitable for real-time sensor-array beamforming applications using custom VLSI circuits.     

基于3D空间信道模型的3D波束赋形技术研究

移动数据流量爆炸式增长对小区吞吐量提出了更高的要求,同时智能终端的急剧增多,使终端之间的信号干扰越来越严重。传统基站天线阵列下倾角是固定的,波束之间干扰较大。随着有源天线技术的逐渐成熟,通过垂直维度的波束赋形动态改变天线的下倾角已经成为可能。本文通过分析已有的空间信道模型,研究了基于球形坐标系统的空间信道模型的建模方法,为3D动态波束赋形技术评估提供了信道基础;并且在提出的3D信道模型基础上评估了动态调整波束的下倾角可以减少用户之间的干扰,提高小区的吞吐量。     

加权子空间拟合相干信源二维波达方向估计

对均匀圆阵列(UCA)二维波达方向估计问题,运用相位激励模式波束形成技术,得到圆阵波束空间实值阵列流形。在波束空间内．研究了相干信源子空间分解技术和加权子空间拟合技术。计算机仿真表明,在波束空间内的加权子空间拟合技术具有良好的相干信源二维波达方向估计性能。     

二维束宽恒定的二阶锥规划波束形成方法

二阶锥规划作为凸优化理论的一个分支,近些年来已应用于波束形成的研究,但在已有研究中基于均匀线阵的一维波束形成研究得较多,且较少考虑不同指向下的束宽恒定问题。因此,基于矩形平面阵,将二阶锥规划的一维束宽恒定波束形成方法扩展到二维作为主要研究目标,首先采用Dolph-Chebyshev加权方法设计出二维参考波束,再以主瓣逼近和旁瓣最小为约束,引入二阶锥规划方法设计了支持不同俯仰角和方位角指向的二维波束。经仿真分析,所提方法可实现在三维空间中的不同指向下的波束形成,且在俯仰角设定后,在不同方位指向下可实现3 dB束宽较恒定的波束,减少了指向对波束特性的影响,方便于应用。     

Transmission Scheme for 2D Antenna Array MIMO Systems with Limited Feedback

Three-dimensional (3D) multiple-input multiple-output (MIMO) systems exploit spatial richness and provide another degree of freedom to transmit signals and eliminate spatial interference. Currently, however, there is no 3D codebook for two-dimensional (2D) antenna array MIMO systems with limited feedback. In this paper, based on the existing 2D codebook, we present a limited feedback and transmission scheme for 2D antenna array MIMO systems. In this scheme, the mobile station (MS) has imperfect channel knowledge, and the base station (BS) only acquires partial information relating the channel instantiation. MS must feed back two channel state information (CSI) instances, i.e., the horizontal and vertical CSIs. After receiving the two CSI instances, the BS interpolates a new vertical precoding vector using the vertical CSI. Then, the BS re-constructs a 3D beamforming vector using horizontal and vertical precoding vectors and compensates the reported horizontal channel quality indicator. System level simulation is employed, and the simulation results show that the proposed method improves the system spectral efficiency and the cell-edge SE significantly.