用于智能天线系统的多小区空时联合处理算法

TD-SCDMA系统同频组网时,邻区用户同样会产生多址接入干扰,而传统的联合检测无法消除.为了抑制邻区干扰,对上行链路接收端提出了一种将联合检测扩展到多个小区并与智能天线相结合的多小区空时联合处理算法.该算法根据对邻区用户信道估计的结果选择其中的强干扰用户,并将邻区强干扰用户和本小区用户的复合信道冲激响应同时纳入空时联合处理的系统矩阵.仿真结果表明,在室内-室外和高速车载信道模型下,采用多小区空时联合处理算法的接收机解调性能有3～4.8 dB的提升.此外,讨论了邻区相关信息的获取、邻区强干扰用户的选择和运算复杂度等具体实现时需考虑的问题.多小区空时联合处理算法可有效消除邻区强干扰用户的干扰,从而大幅提高了同频组网时系统的性能.     

Applications of detection and estimation theory to large array seismology

The statistical theory of signal detection and estimation has been applied to problems in large array seismology. Using this theory the structure of the optimum detector for a known signal and long observation time in additive Gaussian noise is derived. The array processing filter employed by the optimum detector is known as the maximum-likelihood filter. This filter also has the property that it provides a minimum-variance unbiased estimate for the input signal when it is not known, which is the same as the maximum-likelihood estimate of the signal if the noise is a multidimensional Gaussian process. A series of experiments was performed using data from the large aperture seismic array to determine the effectiveness of the maximum-likelihood method relative to simpler methods such as beam-forming. These results provide significant conclusions regarding the design and processing of data from large seismic arrays. The conventional and high-resolution estimation of the frequency-wavenumber spectrum of the background microseismic noise is also presented. The diffuse structure of this spectrum is shown to aid in explaining the relative performance of array processing methods.     

多发射与多接收天线系统盲自适应算法研究

提出了一种用于正交空时分组码(OSTBC:Orthogonal Space-Time Block Code)多发射天线多接收天线系统的盲自适应接收机.该方法主要利用了正交空时分组码的内在特性,给出了一个针对正交空时分组码多发射天线多接收天线系统的无约束代价函数,分析了该函数的全局最小值点.利用该无约束代价函数,通过投影逼近方法给出了递推最小二乘(RLS)自适应算法实现.仿真结果表明:该接收机可以很好的跟踪衰落信道的变化,在不利用导频信号的情况下很好的还原出原始的传输信号.     

天线阵CDMA系统中基于神经网络的盲空时信道估计

提出了天线阵ＣＤＭＡ系统中盲空时信道估计的约束优化神经网络模型,对其全局收敛性进行了分析,并对其性能进行了数值模拟。     

Introduction to space-time adaptive processing

The detection of slowly moving targets by air- and spaceborne MTI radar is heavily degraded by the motion-induced Doppler spread of clutter returns. Space-time adaptive processing (STAP) can achieve optimum clutter rejection via implicit platform motion compensation. The fundamentals and properties of STAP applied to air- and spaceborne MTI radar are summarised     

Using spectral estimation techniques in adaptive processing antenna systems

Improved spectral estimation techniques hold promise for becoming a valuable asset in adaptive processing array antenna systems. Their value lies in the considerable amount of additional useful information which they can provide about the interference environment, utilizing a relatively small number of degrees of freedom (DOF). The "superresolution" capabilities, estimation of coherence, and relative power level determination serve to complement and refine the data from faster conventional estimation techniques. Two conceptual application area examples for using such techniques are discussed; partially adaptive low-sidelobe arrays, and fully adaptive tracking arrays. For the partially adaptive area the information is utilized for efficient assignment of a limited number of DOF in a beamspace constrained adaptive system in order to obtain a stable main beam, retention of low sidelobes, considerably faster response, and reduction in overall cost. These benefits are demonstrated via simulation examples computed for a 16-element linear array. For the fully adaptive tracking array area the information is utilized in an all-digital processing system concept to permit stable hulling of coherent interference sources in the main beam region, efficient assignment/control of the available DOF, and greater flexibility in time-domain adaptive filtering strategy.     

RFID系统中标签天线的设计

本文根据微带天线的基本理论,设计出了一款用于标签的微带对称振子天线.该天线的中心频率为915MHz,回波损耗为-25.596dB;但是该天线阻抗带宽较窄,在VSWR<2的条件下,带宽为20.375%.     

TD-SCDMA系统天馈部分设计的探讨

介绍智能天线的概念和馈线的几种连接方式,对3种不同的天馈连接方式进行详细对比,介绍不同种类的智能天线的特点、作用及其适应的场景,并对天馈系统设计方案的选择提出了建议.     

飞机天线系统EMC设计

飞机天线系统EMC设计的主题思想就是为了保证所有机载设备都能够相互无干扰地调和工作,即各天线在能够正常工作的同时,不会干扰其他天线的工作,还要兼顾天线的性能和工程安装要求,满足整机机载设备正常工作,任务设备也能够正常工作。采用仿真软件进行天线系统电磁兼容的仿真计算后制作了1∶1飞机壳体,进行了天线布局的缩比模型模拟测试,得出了整个飞机的天线布局方案。并提出当出现天线间隔离度太小,可能导致相互间干扰时,从系统层面上考虑分时或分频工作,而需要同时工作的不同频率的天线,应在系统链路上附加滤波器等措施,提高天线发射机对谐波和三阶交调系数的抑制。     

多输入多输出系统中空时分组码的盲信道估计

在空时系统设计中，信道估计是一个关键技术。对一种基于空时分组码的盲信道估计算法进行了研究。在信道输出端进行子空间分解，如果信号子空间是由信道唯一决定的，那么信道参数可被唯一估计为一个常数。提出的算法是基于空时分组码的普通形式，因此可被应用于任何分组码。最后，仿真结果显示了一些特定码字的估计效果。     

Smart-antenna space-time UMTS uplink processing for system capacity enhancement

The system-level performance of Smart-Antenna Space-Time Uplink processing for the frequency division duplex (fdd) mode in umts is investigated. In this paper, a comparative performance evaluation for space-only and space-time processing techniques for different channel models is done. We study the impact of flat fading and spatio-temporal channel models. The results are expressed in terms of multiple-access noise rise and effective data throughput, which are derived by a stationary system simulator. Smart-antennas provide a clear advantage in mixed rate traffic services in comparison to non-adaptive antennas. The system capacity can be enhanced by a factor of 2.5 or higher, depending on the multi-service mix. In urban environments, the estimated capacity of both conventional and smart-antenna systems is lower-bounded by the capacity obtained under the flat fading assumption. The maximum achievable effective throughput is found as a function of both the service mix and the system loading.     

复射线理论应用于天线一体化设计

分析自由空间天线辐射特性的方法已十分成熟,如口径场积分法、平面波谱积分法等,它们大都是行之有效的,但要求对天线及天线罩进行一体化分析时,现有的经典方法往往不能迅速而准确地给出解答,如果用复射线理论这一新方法则可以对某些问题圆满地给出结果.根据复射线理论,利用复源点远场具有的高斯波束特性,无论是在远区或是近轴区域内,复源点场和高斯函数有很接近的相同分布,理论上论证了对于具有高斯波束分布的口径场可以用复源点场来近似模拟.     

时空联合解扩重扩智能天线研究

提出了一种时空联合解扩重扩智能天线.该智能天线在每个阵元输出带有时域均衡器,可以在多径环境下有效消除多径干扰和多用户干扰,提高信噪比.仿真结果表明,该方案的性能优于传统的解扩重扩智能天线.     

智能天线与空时编码技术的性能分析

为了研究智能天线自适应波束形成和空时编码技术(等效于MRRC最大比合并分集技术)这两种无线通信系统的关键技术在3G系统中的选择使用或结合使用的可能性及理论依据，比较了它们各自分别在其适用条件下所能达到的对输入信噪比的最优改善性能，得到了从对平均信噪比的改善的广义角度上讲它们是等效和一致的，它们对信噪比的改善都等于做波束形成的阵元数(或相应的分集支路数)的结论．     

基于时空处理的频率与二维DOA联合估计算法

提出了一种适用于任意阵列的频率与二维DOA联合估计算法.该算法同时利用空域采样与时域采样构造二维时空矩阵,基于2D-ESPRIT方法进行二维参数估计,仅需3个校准阵元就可通过M个阵元估计出M个独立信源的载波频率、方向角和仰角,无需二维谱峰搜索,计算量较小.仿真实验验证了算法的有效性.     

基于相关函数的空时块编码系统的信道估计

提出了空时块编码（STBC）系统中基于相关函数的信道估计的方法。当输入符号向量的各个元素互不相关时，接收信号的相关函数有特定的结构，信道矩阵可以从接收信号的相关矩阵的特征向量中得到，信道估计结果和真实值仅相差一个常数。研究还发现当发送信号的相关函数满足特定的条件时，可以直接从接收信号的协方差得到信道参数，而不需要矩阵分解或者求逆运算。     

Fractal antenna engineering: the theory and design of fractalantenna arrays

A fractal is a recursively generated object having a fractional dimension. Many objects, including antennas, can be designed using the recursive nature of a fractal. In this article, we provide a comprehensive overview of recent developments in the field of fractal antenna engineering, with particular emphasis placed on the theory and design of fractal arrays. We introduce some important properties of fractal arrays, including the frequency-independent multi-band characteristics, schemes for realizing low-sidelobe designs, systematic approaches to thinning, and the ability to develop rapid beam-forming algorithms by exploiting the recursive nature of fractals. These arrays have fractional dimensions that are found from the generating subarray used to recursively create the fractal array. Our research is in its infancy, but the results so far are intriguing, and may have future practical applications     

Joint space-time estimation for DS-CDMA system in fast fadingmultipath channel

A space-time array manifold model is developed for an asynchronous DS-CDMA system over a fast fading channel in a multipath environment. The MUSIC algorithm is applied to the model to extract both the path delays and directions of arrival from the uplink signals. It is shown that this method can resolve the different paths while the conventional approach fails     

Relationships between digital signal processing and control and estimation theory

The purpose of this paper is to explore several current research directions in the fields of digital signal processing and modern control and estimation theory. We examine topics such as stability theory, linear prediction, and parameter identification, system synthesis and implementation, two-dimensional filtering, decentralized control and estimation, and image processing, in order to uncover some of the basic similarities and differences in the goals, techniques, and philosophy of the two disciplines.     

Turbo space-time processing to improve wireless channel capacity

By deriving a generalized Shannon capacity formula for multiple-input, multiple-output Rayleigh fading channels, and by suggesting a layered space-time architecture concept that attains a tight lower bound on the capacity achievable. Foschini (see Wireless Pers. Commun., vol.6, no.3, p.311-35, 1998) has shown a potential enormous increase in the information capacity of a wireless system employing multiple-element antenna arrays at both the transmitter and receiver. The layered space-time architecture allows signal processing complexity to grow linearly, rather than exponentially, with the promised capacity increase. This paper includes two important contributions. First, we show that Foschini's lower bound is, in fact, the Shannon bound when the output signal-to-noise ratio (SNR) of the space-time processing in each layer is represented by the corresponding "matched filter" bound. This proves the optimality of the layered space-time concept. Second, we present an embodiment of this concept for a coded system operating at a low average SNR and in the presence of possible intersymbol interference. This embodiment utilizes the already advanced space-time filtering, coding and turbo processing techniques to provide yet a practical solution to the processing needed. Performance results are provided for quasi-static Rayleigh fading channels with no channel estimation errors. We see for the first time that the Shannon capacity for wireless communications can be both increased by N times (where N is the number of the antenna elements at the transmitter and receiver) and achieved within about 3 dB in average SNR about 2 dB of which is a loss due to the practical coding scheme we assume-the layered space-time processing itself is nearly information-lossless.