Energy-efficient hybrid beamforming for millimeter-wave-based massive multiple-input multiple-output system

The advanced wireless communication system requires abridged energy consumption, enhanced data rate, and good signal coverage. The massive MIMO technology for 5G systems has been developed to accommodate several users simultaneously with superior throughput. The claim for high data rate wireless communication services is expanding quickly as time goes. Thus, the key difficulty is that as the number of users grows, the number of phase shifters grows as well, causing the system to consume more power; as a result, the system's energy efficiency decreases. Hybrid beamforming has recently emerged as an attractive technique for millimeter-wave (mmWave) communication systems. The analog beamformer in the RF domain and digital beamformer in the baseband are coupled through a minimal number of RF chains in hybrid beamforming architecture. Hybrid beamforming utilizes fewer RF (radio frequency) chains than the total number of antennas to have a lower energy consumption design. The hybrid beamforming for a mmWave-based massive MIMO system through different phase shifter selection mechanisms is proposed to achieve the highest energy efficiency for mmWave communications systems. The fully connected with phase shifter selection, sub-connected with phase shifter selection (SPSS), and fully connected and sub-connected with phase shifter selection with halved and doubled switches are considered for this research. The simulation results show the SPSS with halved switch outperforms on energy efficiency.     

Independent component analysis for multiple-input multiple-output wireless communication systems

Independent component analysis (ICA), an efficient higher order statistics (HOS) based blind source separation technique, has been successfully applied in various fields. In this paper, we provide an overview of the applications of ICA in multiple-input multiple-output (MIMO) wireless communication systems, and introduce some of the important issues surrounding them. First, we present an ICA based blind equalization scheme for MIMO orthogonal frequency division multiplexing (OFDM) systems, with linear precoding for ambiguity elimination. Second, we discuss three peak-to-average power ratio (PAPR) reduction schemes, which do not introduce any spectral overhead. Third, we investigate the application of ICA to blind compensation for inphase/quadrature (I/Q) imbalance in MIMO OFDM systems. Finally, we present an ICA based semi-blind layer space-frequency equalization (LSFE) structure for single-carrier (SC) MIMO systems. Simulation results show that the ICA based equalization approach provides a much better performance than the subspace method, with significant PAPR reduction. The ICA based I/Q compensation approach outperforms not only the previous compensation methods, but also the case with perfect channel state information (CSI) and no I/Q imbalance, due to additional frequency diversity obtained. The ICA based semi-blind LSFE receiver outperforms its OFDM counterpart significantly with a training overhead of only 0.05%.     

Design of a mixed fuzzy controller for multiple-input multiple-output systems

Multiple-input multiple-output (MIMO) systems usually have characteristics of nonlinear dynamics coupling. Therefore, the difficulty in controlling MIMO systems is how to overcome the coupling effects between the degrees of freedom. The computational burden and dynamic uncertainty associated with MIMO systems make model-based decoupling impractical for real-time control. This work develops a mixed fuzzy controller (MFC) to solve this problem and improve control performance. This study first designs a traditional fuzzy controller (TFC) from the viewpoint of a single-input single-output (SISO) system for controlling each degree of freedom of a MIMO system. Then, an appropriate coupling fuzzy controller is also designed according to the characteristics of the system’s dynamics coupling and incorporated into a TFC to compensate for coupling effects between the degrees of freedom. This control strategy can not only simplify the implementation problem of fuzzy control, but also improve control performance. The state-space approach for analyzing the stability of fuzzy control systems is applied to evaluate the stability and robustness of this intelligent mixed fuzzy controller. To verify the applicability of the proposed mixed fuzzy controller, this work presents a two-link robotic manipulator with a complex dynamic model for a MIMO system to evaluate the stability and robustness of the MFC by numerical simulation, and to examine the control performance by comparing the simulation results of the MFC with those of a TFC for this MIMO system.     

Performance analysis of large-scale MIMO system for wireless backhaul network

In this paper, we present a performance analysis of large-scale multi-input multi-output (MIMO) systems for wireless backhaul networks. We focus on fully connected N nodes in a wireless meshed and multi-hop network topology. We also consider a large number of antennas at both the receiver and transmitter. We investigate the transmission schemes to support fully connected N nodes for half-duplex and full-duplex transmission, analyze the achievable ergodic sum rate among N nodes, and propose a closed-form expression of the achievable ergodic sum rate for each scheme. Furthermore, we present numerical evaluation results and compare the resuts with closed-form expressions.     

多输入多输出可见光通信的天线布局研究

通过改变LED及光电探测器(PD)的 空间分布,得到不同的天线布局,同时通过改 变LED间距dTX、发射端和接收端平面的高度差h等条件,得到了不同的信道传输矩阵H,仿 真分析了以上各种情况下的室内可见光通信系统(VLC)的性能。结果表明,影 响VLC性能的关键参数包含最小欧式距 离dmin和行列式Det(H)。根据系统的关键 参 数,将天线布局分为圆形布局和格点布局两类,圆形布局是指所有LED或PD均 匀地分布在一个 圆上,而格点布局是指所有LED或PD均分布在二维平面中的格点上。仿真结果表明,当dTX变化时,在采 用圆形布局的系统中,行列式Det(H)是影响误码率(BER)的关键因素 ;在采用格点布局的系统中,dmin和Det( H)均是影响系统误码率的关键因素,但在d TX的一定范围内dmin是决定系统性能的关键因素 。而当h发生变化时Det(H)是影响系统性能的 关键因素。     

MIMO水下无线光通信系统性能解析研究

为了消除海洋湍流引起的信号衰落和衰减,在基 于BPSK调制的水下无线光通信(underwater wireless optical communication,UWOC)系统中引入了MIMO(multi-input multi-outpu t)技术。在 假设海洋湍流模型为log-normal分布基础上,得出了球面波光束在弱海洋湍流传输的闪烁 指数计算公 式。借助于Gauss-Hermite正交积分近似公式,推导了UWOC系统分别采用SISO(single-in put single-output)、SIMO(single-input multi-output)、MIMO三种技术,且接收端 采用等增益合并法时, 系统误码率(bit error rate,BER)的解析公式。应用此解析公式,数值仿真观察了系统 误码率在不同 的信噪比下受三种海洋参数(即均方温度耗散率,单位质量液体中的湍流动能耗散率,温度 和盐度波 动的相对强度)以及系统通信距离的影响。仿真结果表明,UWOC系统采用MIMO技术,在较小 的 均方温度耗散率、较小的温度和盐度波动的相对强度、较大的湍流动能耗散率的海洋中,以 及通过较 短的通信链路都可以得到更优的误码率性能。     

Performance analysis of multi‐input multi‐output systems with maximum likelihood detection over shadowed fading channels

Multiple‐input multiple‐output (MIMO) transmission techniques constitute an important technology in modern wireless communication. Hence, performance analysis methods for such systems are of considerable interest. This paper considers first the average pairwise error probability for uncoded MIMO systems employing maximum likelihood detection over a composite Rayleigh‐Lognormal fading channel with spatial correlation. It provides general results, applicable also to a wider class of shadowing models, concerning asymptotical diversity gains and shows that they are not changed by such shadowing. Then, analytical evaluation techniques for bit‐error‐rate (BER) over composite Rayleigh‐Lognormal fading channels, based on the truncated union bound and the transfer function, are considered. Furthermore, these techniques are modified for applications over spatially correlated channels. This paper shows that such performance evaluation techniques provide good approximations to BER of spatially uncorrelated MIMO systems and also in the presence of moderate spatial correlation, over Rayleigh‐Lognormal fading channels. Copyright © 2013 John Wiley & Sons, Ltd.     

Sum Throughput Enhancements in Quality of Service Constrained Multiuser MIMO OFDM Systems

In many wireless applications, such as video streaming, data transfer or mobile Internet, user satisfaction is directly related to the transmission rates of the wireless channels in the physical layer. If the transmission rate of one user undercuts a certain level, the quality of the application becomes unacceptable. Furthermore network operators are interested in maximizing overall system throughput. However, this aim can usually not be achieved without violating these minimum rate constraints. In this article we therefore consider a practical resource allocation scheme for MIMO OFDM systems that achieves both aims without requiring computationally expensive optimization algorithms. The main part consists of a user classification. Users in one group will only be served with their minimum required rates. The remaining users can exploit the additional system resources more effectively for strong throughput increases and are therefore put in the other group. An iterative application of the proposed scheme enables additional throughput increases and the consideration of maximum transmission rates.

基于分布式MIMO矿井无线通信系统的研究

针对矿井巷道的特殊环境以及无线通信问题,通过MIMO系统和分布式天线系统,建立了井下分布式MIMO信道模型。仿真结果表明,分布式MIMO系统具有更高的信道容量。基于分布式天线的灵活设置,分布式MIMO系统既提高了频谱利用率又减少了信号盲区,最终扩大了井下信号覆盖范围,提高了整个系统的信道容量。     

Investigation of signal variance,bit error rates and pulse dispersion for DSPN signalling in A mobile dense scatterer ray tracing model

The canonical ray tracing model of R. H. Clarke is used to validate the concept of mitigation bandwidth as used to predict DSPN spread spectrum signal variability at a mobile receiving antenna in dense scatterers. Illustrative examples of chip pulse dispersion are presented, and bit error rate performance is explored under the assumption of slow fading. The pulse dispersion is seen to pose potential obstacles to any eventual chip timing extraction and radio-location ranging functions. Serendipitously, the performance of a DSPN embodiment of a 180° DPSK data link is seen to approximate closely that of a corresponding narrowband Rician fading link, even though no specular signal component is available to the DSPN link. The parameters of the equivalent Rician link are easily predicted from those of the DSPN link.     

Performance analysis of compact MIMO system based on network theory

The impact of mutual coupling on the performance of multiple-input multiple-output (MIMO) systems with compact antenna arrays is analyzed. This article aims to use the 5-parameter modeling approach to examine the impact of mutual coupling on three system-related performance measures: antenna correlation, efficiency and bandwidth. It is shown that implementing a good matching network can drastically improve the system performance in the presence of strong mutual coupling. Experiment results indicate the superiority of cross-shaped antenna to dipole antenna.     

空间三维分层仿真在LTE无线网络规划优化中的应用

研究一种预测室外宏站对建筑物室内覆盖效果的方法。在LTE无线网络规划仿真中，如何考察室外宏站对建筑物室内的覆盖效果是一个值得考虑的问题。本文主要基于射线跟踪技术对不同高度的楼层进行仿真，然后综合分析各楼层的覆盖指标，基于一定判定标准分析室外宏站对某建筑物的覆盖情况，最后给出建筑物是否需要部署室分的建议。     

Improving a Hybrid Method of Indoor Propagation Modeling for Wireless Communications Systems

1　IntroductionThewirelesscommunicationsystemshavebeendevelopedrapidlyintherecentyears.Ithasnotonlycalledresearchers’attentiontomodelingtechniquesinInternet[1 ] ,butalsomoreandmorepeopleen gagedin propagationmodelingforindoorwirelesscommunications.Theeffectivedesign ,assessmentandinstallationofaradionetworkinanindoorenvi ronmentrequireanaccuratecharacterizationoftheradiopropagationchannel.Raytracingisapopularmethodforthepredictionofradiochannelcharacter isticsofwirelesscommunicationsystems.R…     

Performance analysis of time-hopping m-ary UWB wireless system using V-BLAST algorithm

Ultra WideBand (UWB) transmissions are attractive for low power, baseband asynchronous multiple access and peer-to-peer wireless communications. Multiple Input Multiple Output (MIMO) technology is useful in combating against multipath and at the same time improves system performance by using multielement antennas at both transmitter and receiver. This letter proposes a time hopping M-ary UWB systems using V-BLAST algorithm, and power control is considered for better performance. Simulations are provided to compare performance with different antennas.     

Optimal LED deployment for mobile indoor visible light communication system: Performance analysis

The maximization of the system performance in a typical indoor visible light communication system is a major challenge while minimizing the overall resources for the deployment. The intelligent smart lighting systems can be optimized to reduce the requirement of various resources without compromising on the system performance. In this paper, we investigate the optimization of the light emitting diode (LED) resources within an indoor room scenario using a most efficient stochastic optimization technique-Hyper-heuristics evolutionary algorithm (HypEA). The performance of the communication system has been measured in terms of average area outage ratio, computational efficiency and mobility area analysis. The performance of the HypEA has been compared against the most experimented algorithm-Particle swarm optimization (PSO). The detailed investigation and analysis shows that HypEA is computationally more efficient and is able to achieve full mobility with almost 12.5 percent fewer resources as compared to PSO.     

面向未来无线通信系统的小蜂窝网络综述

为了满足人们日益增长的数据流量需求,未来无线通信系统将向更小的小区部署迁移.小蜂窝网络是下一代无线通信系统的关键技术,也是适应未来更加复杂通信环境的有效途径.首先介绍了小蜂窝网络的基本概念,论述了其主要的技术特点和独特的应用优势,分析了其在未来无线通信系统中与其他各种技术可能的融合场景并讨论了对应的特点和存在的难题;然...     

多天线系统中的多维极化分集性能分析

分别研究了六维极化元天线和三维极化偶极子天线模型的空域相关矩阵,计算了系统的信道容量和有效空间自由度(EDOF).通过定义更广义的角谱分布,指出了在六维极化的元天线模型中,平均入射角对系统性能起着关键的作用,而入射角谱的对称性也是导致元天线模型中低相关性的主要原因;通过对三维正交极化的半波偶极子结合矩量法和蒙特卡罗方法计算,论证了在散射丰富条件下应用三维极化天线,可获得接近三倍单天线信道容量的增益,从而验证了已有的测试结果;最后给出了三维正交极化天线的设计思路.     

多径多用户环境下超宽带脉冲无线通信系统性能

超宽带脉冲无线电是正在发展中的新型高速无线接入技术。该文首先分析了超宽带发射信号实现多址通信的原理。为了研究在多径环境下的系统性能,引入了确定型两径和统计型S-V两种典型室内信道模型。通过仿真试验得到在此信道条件下系统的误比特率。结果表明,在多径多用户环境下,符号间干扰和多址干扰使系统性能下降;当接入用户数达到一定值后,多址干扰成为降低系统性能的主要因素,采用接收天线分集能提高系统性能。     

SSC-MRC混合合并接收系统在n-Rayleigh信道下的性能分析

在n-Rayleigh信道下,研究了结合切换驻留合并(SSC)与最大比合并(MRC)的混合合并接收系统的平均符号误码率(ASEP)性能。基于矩生成函数(MGF)方法,推导了SSC-MRC混合合并接收系统在n-Rayleigh衰落信道上采用相干检测的M进制相移键控(PSK)、正交幅度调制(QAM)、脉冲幅度调制(PAM)等几种数字调制方式的ASEP的精确表达式,然后对不同系统条件下的ASEP性能进行了数值仿真,结果表明:随着分集支路数的增大,衰弱因子的减小,系统的ASEP性能得到了很好的改善,验证了理论分析结果的正确性。     

一种针对频率选择性MIMO信道的新型空时分层迭代检测算法

本文针对FS-BLAST算法中的误码扩散问题提出了一种新的分层迭代方法：部分最大似然分层迭代（MLIC）算法。FS-BLAST由于采用了干扰对消的方案,不可避免的产生了误码扩散问题。在本文中,提出了一种新的部分最大似然分层迭代方案,它在分层迭代算法中引入最大似然的概念,是最大似然检测和分层迭代算法的折衷。从实验仿真中,可以看出,这种改进的算法比传统的FS-BLAST和已有的迭代算法具有更好的系统性能。