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1.
本文首先概述了多径信道传输特性,在此基础上,重点讨论了基于智能天线抗多径干扰技术的理论,并对基于CMA算法的智能天线抑制多径干扰进行了计算机仿真。  相似文献   

2.
移动通信中的CMA阵列具有抗多径干扰和抗共信道干扰能力。本文理论分析了实际信号环境下CMA阵列的抗多径干扰和抗共道干扰能力,并进行了计算机仿真,仿真结果表明,CMA阵列的抗多径干扰性能受随机相移、信号幅度、信号空间分布等因素的影响,当所需信号与多径干扰信号空间卫离度越大,CMA阵列的抗多径干扰性能越好。CMA阵列的抗共信道干扰性能较抗多径干扰性能要好,只要所需用户信号和共信道干扰信号不在同一入射方向,CMA阵列就可以将干扰信号抑制掉。  相似文献   

3.
一种DS-CDMA无线反向链路空间分集方案研究   总被引:1,自引:0,他引:1  
本文利用自适应天线阵列分离出多径信号,利用RAKE消除多径衰落。导频位符号辅助(PSA)信道估计用来对RAKE的输入端进行加权,天线阵列的加权系数的自适应更新是采用RLS算法而得。结果表明,该方案具有很强的抗多径干扰和多址干扰的能力。  相似文献   

4.
移动通信中.在基站同时处理信道间干扰和多径衰落是一个比较复杂的问题。本文通过对移动通信中存在的多径衰落进行分析,结合智能天线中的自适应阵列天线的特点.提出了一个方案。初步仿真结果表明该方案对处理干扰和多径衰落有明显的效果,可为智能天线的进一步研究提供参考。  相似文献   

5.
测向机的性能取决于多种设计参数,如:天线阵几何结构、放大器、混频器、滤波器、模拟/数字转换器、信号处理算法、处理能力等,其中天线阵列的几何结构,即天线阵元个数和位置对系统的性能影响最大拌争别是对受多径传播或同信道干扰影响引起失真的来波,天线阵列的设计限制了测向精度、灵敏度和稳定度。  相似文献   

6.
电子百科     
智能天线技术 智能天线也叫自适应阵列天线,它由天线阵、波束形成网络、波束形成算法三部分组成。它通过满足某种准则的算法去调节各阵元信号的加权幅度和相位,从而调节灭线阵列的方向阔形状,以达到增强所需信号抑制干扰信号的目的。智能天线技术适宜于TDD方式的CDMA系统,能够在较人程度上抑制多用户干扰、提高系统容量。但是由于存在多径效应,每个天线均需一个Rake接收机,从而使基带处理单元复杂度明显提高。  相似文献   

7.
为满足卫星导航领域抗多干扰的应用需求,提出基于小孔径阵列天线的卫星导航多干扰抑制方法,分析了天线极化孔径对静态方向图和抗干扰性能的影响、进行了基于小孔径阵列天线的空时、空频和多维域级联抗干扰算法设计,基于4阵元阵列天线系统进行了多干扰抑制的试验验证。测试结果表明,所采用的方法可有效抑制多干扰,具有较高的实际装备应用价值。  相似文献   

8.
短波通信存在着多径衰落和干扰的问题,影响了通信的质量。通过使用智能天线,可以提高通信质量和可靠性。但是短波多径环境中会产生多个相干信号,造成智能天线的波达方向(DOA)识剥模糊。本文利用短波信号的循环平稳特性,结合均匀线性阵列,提出了在短波环境中识别DOA的前向空间平滑Cyclic Music方法。  相似文献   

9.
GPS天线阵列接收技术能有效地对抗人为干扰,其自适应算法的选择影响阵列的抗干扰性能。当有用信号的实际来向与理论估计值有误差时,自适应算法不但要求对干扰有很强的抑制能力,而且自身应具有稳健性。结合GPS天线阵列接收信号特点,从理论上分析比较四种自适应算法的抗干扰性能,得出了一种较优的算法,并由仿真实验进行了验证。  相似文献   

10.
智能天线与现代移动通信   总被引:2,自引:0,他引:2  
近年发展起来的CDMA移动通信系统技术相对于FDMA,TDMA系统个有较大的容量,但由于多径干扰,多址干扰的存在,其容量优势并没有得到充分的发挥,如果在基站上采用智能天线可以降低这些干扰的影响,提高系统的性能,本文通过对智能天线的认识,优势的阐述,从而引发智能天线在现代移动通信中的重要性。  相似文献   

11.
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.  相似文献   

12.
The performance of code division multiple access (CDMA) systems can be affected by small scale fading such as Rayleigh fading channel. In this paper, the application of smart antenna and Large Area Synchronous CDMA (LAS CDMA) systems, which introduce directional diversity channel, is presented. A novel interference cancellation scheme through dynamic space code (DSC) algorithm is briefly described. The directional diversity can be realized from the directional gain of smart antenna system. It can be found that when the number of elements in smart antenna is increase the directional gain of antenna system is much higher than single antenna. The system performance analysis in term of error probability is compared between traditional and LAS CDMA systems in both single and smart antenna systems. From the performance analysis it is found that CDMA system is more susceptible to multipath fading channel than interferences from existing users.
Mahamod IsmailEmail:
  相似文献   

13.
几种多天线系统的信道容量比较   总被引:3,自引:1,他引:2  
王艺  赵明  周世东  姚彦 《电子学报》2002,30(6):787-790
分布式天线、智能天线和扇区天线是三种能大大提高无线通信系统容量的技术,本文比较了这三种多天线系统的信道(Shannon)容量.假设每个用户在所有接收天线上的总功率相等,分析表明分布式天线和扇区天线的信道容量远大于智能天线的信道容量,而传统的观点认为智能天线在抑制干扰时要比扇区天线的性能更好,从而获得更大的系统容量.另外我们分析了分布式天线在渐近条件下的信道容量,即用户数K和载波数M都趋近无穷大,而保证α=K/M一定.分析表明在α较大时,分布式天线与比扇区天线的信道容量差趋近常数0.44比特/秒/维,但是如果考虑分布式天线的分集增益,那么分布式天线的信道容量要远大于扇区天线.  相似文献   

14.
不采用自适应算法的智能天线系统   总被引:2,自引:0,他引:2  
本文提出了一种基于等旁瓣针状波束方向图的智能天线。为了与采用自适应算法的智能天线进行对比,本文分别模拟了这两种不同天线用于CDMA系统时的扩容能力。模拟结果表明,在CDMA系统中无需采用自适应算法,只需用等旁瓣针状波束智能天线,就可以达到与自适应智能天线相似的扩容性能。等旁瓣针状波束智能天线的优点是:无需迭代、响应速度快,鲁棒性好。  相似文献   

15.
Differing from FDMA, TDMA, and CDMA, space division multiple access (SDMA) uses space resources to improve communication system performance. Utilizing the smart antenna system is an approach to realize the SDMA technique. Smart antenna systems using the beamforming technique can reduce the co‐channel interference and multipath fading to increase the channel capacity and communication quality. In this study the smart antenna system and rake receiver are integrated. The performance of spatial–temporal structure applied to the W‐CDMA system is evaluated. From the cumulative distribution function simulation results, W‐CDMA system with spatial–temporal algorithm can exactly provide SINR gain to improve the system performance and capacity. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

16.
The incorporation of directional sensitivity, provided by so-called adaptive antennas is useful in suppressing interfering signals that arise from spatially distinct mobile sources. The problem is that in a cellular radio environment where multipath exists, the standard adaptive antenna using reference signals may not properly lock on the desired signal. This is because the signal correlation matrix processed by the antenna may then be close to singular and standard algorithms fail. Also, most standard algorithms need to cooperate with the receiver for the spatial discrimination of signals. A smart antenna utilizing a blind algorithm is of interest since the antenna may not need to get any feedback from a receiver for the adjustment of weight coefficient for spatial processing and can stand alone to be plugged into any kind of receiver structure.In this paper, we address the convergence property of a Constant Modulus Algorithm which is a blind algorithm and, if employed, can provide no need for an antenna to cooperate with a receiver attached. By identifying a relationship between the weight coefficients and output signal amplitude, we also evaluate the performance of such a stand-alone antenna plus a CDMA matched filter reception. Our results show that for a three element CM array, the BER of a desired user with the other interfering users is much better than a conventional correlation receiver for a single user case since the array suppresses interferences and achieves array gain in SNR.  相似文献   

17.
Dynamic Spatial Channel Assignment for Smart Antenna   总被引:1,自引:0,他引:1  
The paper describes an optimal dynamic channel assignment algorithm for smart antennas. This algorithm can deal with the Spatial Division Multiple Access (SDMA) and traditional channel multiple accesses (FDMA, TDMA, or CDMA) simultaneously to enlarge the capacity of communication systems. This algorithm has several merits, including less computer time, the largest capacity, and avoidance of co-channel interference. The paper also describes the idea of a spatial channel pattern, in which several users can share a channel. Several simulation results are presented in the paper.  相似文献   

18.
目前对智能天线的研究主要侧重于智能天线的自适应波束形成算法和智能天线的应用两个方面,并已提出了不少高效的智能天线算法,智能天线的理论已经很成熟。对智能天线应用研究最多的是它在第三代移动通信中的应用。文中提出智能天线在GPS(全球定位系统)中的一种应用方案,它基于功率倒置算法,用DSP实现。  相似文献   

19.
In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.  相似文献   

20.
针对通信系统中多径干扰难以估计和抑制的问题,提出了一种地面采用智能天线自适应跟踪的方法。以均匀直线阵为基础,采用前后向空间平滑算法对阵列接收相干信号进行预相干处理,再利用MUSIC(Multiple Signal Classification)算法实现信号来波方向(Direction of Arrival,DOA)估计,应用一种新的对角加载稳健波束形成技术减小主峰偏移,实现多径干扰抑制。仿真分析验证了所提算法的正确性和有效性,系统具有良好的稳健性,具有较高的工程实践价值。  相似文献   

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