超宽带多发多收雷达系统的信号源设计及实现

多发多收超宽带雷达和通信系统是当今研发热点,国内外多有相关报道,而信号源的设计及实现是其关键技术之一。目前用扩频模块来实现GHz 脉冲信号的信号源,结构复杂、成本高。对此,设计和制作了一款由可编程逻辑器件FPGA 和DDS 芯片组成并产生GHz 脉冲信号的信号源,其核心是ADI公司的DDS芯片AD9914和Xilinx公司的Kintex-7系列FPGA芯片作控制芯片,此信号源获得了高达1.4 GHz的大带宽多通道同步雷达脉冲信号,频率切换时间达到ns级,且频率、相位和幅值都可控,其性能在国内具有先进性,并具有实际应用价值。     

Computationally efficient DOD and DOA estimation for bistatic MIMO radar with propagator method

In this article, we consider a computationally efficient direction of departure and direction of arrival estimation problem for a bistatic multiple-input multiple-output (MIMO) radar. The computational loads of the propagator method (PM) can be significantly smaller since the PM does not require any eigenvalue decomposition of the cross correlation matrix and singular value decomposition of the received data. An improved PM algorithm is proposed to obtain automatically paired transmit and receive angle estimations in the MIMO radar. The proposed algorithm has very close angle estimation performance to conventional PM, which has a much higher complexity than our algorithm. For high signal-to-noise ratio, the proposed algorithm has very close angle estimation to estimation of signal parameters via rotational invariance technique algorithm. The variance of the estimation error and Cramér–Rao bound of angle estimation are derived. Simulation results verify the usefulness of our algorithm.     

MIMO系统中空时分组编码的信道容量

在多输入多输出（MIMO）系统中，建立空时分组编码模型，在分析瑞利衰落下正交空时分组码接收信噪比的基础上，得到了正交空时分组编码信遗容量的表达式，并采用数值计算的方法对其进行分析论述，得出在接收天线数一定的情况下，增加发送天线数所能得到的信道容量的上界。同时，分析证明，在发送天线数一定时，正交空时分组编码信道容量随接收天线数的增加而增加。在接收天线数一定时，信遗容量也随着发送天线数的增加而增加，但当发送天线数增加到一定数量时容量的增加就变得不十分明显。     

一个基于IEEE802．11P标准能WAVE模型样机

基于IEEE802．11p标准的车辆通信环境下的无线接入（WAVE）系统为未来的智能交通系统建造了功能性架构,旨在安全性、有效性和方便性方面极大地改善交通环境。文章阐述了WAVE系统的背景、关键技术及其对社会的深刻影响,报告了密歇根大学迪尔拜分校车载通信和网络中心进行的相关研究和进展,包括一个基于现场可编程门阵列（FPGA）的WAVE模型样机和车载网络仿真软件。     

3D channel modeling and space-time correlation analysis for V2V communications

To match complex wireless propagation scenarios,an improved 3D geometry-based stochastic model was proposed for vehicle to vehicle (V2V) communications channel.The exact relationship between the azimuth angle and elevation angle was taken into account and the corresponding space–time correlation function and space–Doppler power spectral density were derived,and the influence of important factors was analyzed.The observations and conclusions show that correlation characteristics is closely related to distribution of the scatterers and the angle of the antenna array under the non-isotropic scattering environment and is affected by the elevation angle of the antenna array under the isotropic scattering environment.And the space-time correlation characteristics in high vehicular traffic density is significantly lower than that in low vehicular traffic density.The corresponding simulation model is also derived by using a reasonable parameter calculation method.The simulation results validate the rationality of proposed model.It greatly improves analysis and simulation efficiency of V2V MIMO system.     

CS quadrilinear model-based angle estimation for MIMO radar with electromagnetic vector sensors

In order to estimate the angles for bistatic MIMO radar with electromagnetic vector sensors, we link the compressed sensing (CS) theory with quadrilinear model, and propose a novel angle estimation algorithm. In the proposed algorithm, the received data is firstly arranged into a quadrilinear model and then it is compressed according to the compressed sensing theory. We then perform quadrilinear decomposition on the compressed quadrilinear data model via the quadrilinear alternating least square (QALS) algorithm and finally obtain the automatically paired angle estimates with sparsity. Owing to compression, the proposed algorithm has smaller storage requirement and lower computational complexity than the conventional quadrilinear decomposition-based algorithm. Moreover, our algorithm has higher angle estimation accuracy than the estimation signal parameters via rotational invariance techniques (ESPRIT) algorithm and its estimation performance is close to that of the conventional quadrilinear decomposition-based algorithm. Our proposed algorithm needs neither additional pair matching, nor spectral peak searching, and it can be applied to both uniform and non-uniform arrays. Effectiveness of our proposed algorithm is assessed through various simulation results.     

基于长电偶极子和大磁圆环的新型电磁矢量传感器双基地多输入多输出雷达角度和极化参数联合估计

针对常规双基地电磁矢量传感器多输入多输出(multiple-input multiple-output,MIMO)雷达中短电偶极子(L/λ<0.1)和小磁环((2πR/λ)<0.1)辐射效率不足问题,本文根据实际应用中电磁矢量传感器的有效长度来设计新型的发射电磁矢量传感器阵列和接收电磁矢量传感器阵列.首先,通过平行因子...     

分布式发射天线MIMO信号的最优线性检测

 在分布式发射天线多输入多输出(MIMO)系统中,信道传播时延使各个发射天线的符号异步到达接收天线.接收信号符号间干扰的特殊性使分布式发射天线MIMO信号的线性检测算法更加复杂,最优线性检测算法也不能直接由最小均方误差(MMSE)准则得到.针对这一问题,提出了基于MMSE准则的分布式发射天线MIMO信号的最优线性检测算法:先最大比合并,再最小均方误差检测.并且,通过界定误码率上下限,得到其分集阶数.仿真结果验证了最优线性检测接收端信号处理方式的正确性.     

Turbo Decoding of Super-Orthogonal Space-Time Trellis Codes in Rayleigh Fading Channels

Space-time trellis codes have shown to provide a good performance in Rayleigh fading channels. Recently Super-orthogonal space-time trellis codes have shown to outperform these codes, and also provide a systematic design method to maximize diversity and coding gain in quasi-static Rayleigh fading channels. We investigate the performance of these new codes in rapid Rayleigh fading channels and further propose two concatenated versions of these codes. We further investigate the effect of imperfect channel state information on one of the concatenated versions. Some simulation results of the various concatenated schemes in quasi-static and rapid Rayleigh fading channels are presented. Jayesh N. Pillai received the B.Tech degree in Electrical and Electronic Engineering from the University of Calicut, Kerala, India in 2001. He is currently pursuing an MScEng degree in Electronic Engineering at the School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal, Durban, South Africa. His research interests are in the area of wireless communications, including multiple-antenna systems, space-time coding and channel coding. Stanley Henry Mneney obtained his B.Sc.(Hons) Eng. Degree from the University of Science and Technology, Kumasi in Ghana in 1976. In 1979 he completed his M.A.Sc. from the University of Toronto in Canada. In a Nuffic funded project by the Netherlands government he embarked on a sandwich Ph.D. programme between the Eindhoven Univesity of Technology and the University of Dar es Salaam, the latter awarding the degree in 1988. His co-supervisors were Prof Jens Arnbak and Prof Ramje Prasad representing the two Universities. The research area was on the application satellite technology to provide low cost systems and services to the rural population in the developing countries.Prof Mneney has taught at the Universities of Dar es Salaam, Nairobi, Durban Westville and he is currently an Associate Professor and Deputy Head of School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal in South Africa. His research interest includes Signal and Image processing, radio propagation and communication systems.     

Improvement of a MIMO antenna structure with combination of transmit beamforming and spatial multiplexing

Downlinks of the cellular systems generally have more transmit antennas than receive antennas. To efficiently exploit all antenna resources, a technique that combines the advantage of beamforming and spatial multiplexing has been proposed, which partitions the transmit antennas into neighboring sub-groups. In this article, this technique is further improved by Eq. （1） allowing non-contiguous antenna grouping, and Eq. （2） adopting two new grouping criteria： minimum signal distance maximization （MSDM） criterion and maximum correlation coefficient minimization （MCCM） criterion. Simulation results indicate that these improvements can bring noticeable gains in the Rayleigh fiat fading channel environment.