宽带干扰自适应旁瓣相消的方法研究

依据自适应旁瓣相消原理,着重分析了宽带干扰信号对旁瓣相消性能的影响,针对宽带干扰影响下,主辅天线间的波程差、主辅天线通道频率特性的不一致性以及主天线旁瓣的频率敏感特性等引起的自适应旁瓣相消系统的主辅天线2通道信号的去相关作用,采用了主天线通道均衡和子带自适应相消2种方法改善带宽特性,并通过MATLAB仿真验证,仿真结果表明该两种方法均可明显改善系统的相消性能,达到良好效果。     

雷达旁瓣相消和旁瓣匿影抗干扰技术

自适应旁瓣相消（ASLC）是雷达抗有源干扰的有效方法。它采用空间滤波技术，通过辅助接收通道在干扰方向形成波束图的零点．实现对干扰信号的抑制；而旁瓣匿影则可以用来对付另一类由天线副瓣进入接收机的干扰．包括脉冲型干扰、强目标回波、杂波干扰等。本文论述了自适应旁瓣相消和旁瓣匿影的基本原理，实现方案，并对仿真结果进行了分析。     

两种修正的自适应通道均衡方法

在常规雷达加装的自适应旁瓣相消(ASLC)系统中,天线至接收机前端馈线部分的相位不一致性通常不可忽略。而现有的自适应通道均衡方法是在接收机前端注入校准信号进行均衡,只能对接收机的幅相不一致性进行校正,对馈线部分的相位失配却无能为力,因此影响了ASLC的对消性能。该文提出了两种修正的自适应通道均衡方法,它们能同时校正接收机与馈线部分的幅相不一致性。理论分析和实验结果验证了这两种方法的有效性。     

数字阵列雷达通道自适应均衡器的一种设计方法

通道之间的幅相不一致性和通道带内频响的不一致性严重影响了数字阵列雷达的性能,采用自适应均衡技术可以解决通道的一致性问题。高性能的数字信号处理芯片可以在较高的运算速度下,实现通道的自适应均衡。本文采用最小二乘广义求逆法求解均衡器系数,提出了利用多通道下变频芯片中的可编程滤波器进行均衡的方法。最后通过仿真和测试结果,分析了均衡性能。     

天线阵元通道失配校正的FPGA实现

基于FPGA的阵元通道校正是自适应天线技术用于实践的重要基础。给出了一种天线阵元通道失配校正方法的FPGA实现方案。仿真结果表明,该实现方案能够有效校正阵元通道失配,现已成功应用于实际的自适应阵系统。     

通道不一致性对GPS天线自适应算法的影响

GPS信号到达地面终端时通常非常微弱,极易受到传输环境和去其他信号的干扰。功率反演(Power-Inversion)算法应用于GPS自适应天线阵可以很好地抑制干扰信号,但由于阵列天线通道存在幅相不一致,这会对自适应抗干扰算法产生很大影响。通过对自适应天线阵列及通道不一致性进行建模,经过理论分析和计算机仿真,以QRD-SMI算法为例,验证了自适应算法在一定条件下能够克服天线通道不一致,从而有效地抑制干扰信号,所得结论有利于指导工程应用。     

雷达天线伺服系统自适应离散控制探究

为了提高雷达系统的性能,要求雷达天线伺服控制系统稳定性高、动态特性好、稳态误差小以及鲁棒性强。针对如上需求,提出了一种自适应离散控制方案,它由位置反馈控制器、自适应零相差前馈控制器（ZPETC）和自适应零相差滤波器（ZPEF）组成。计算机仿真结果表明,所提出的控制方案可实现雷达天线快速、精确的跟踪,而且具备针对参数摄动的较强适应性。     

智能天线技术在3G中的应用

自适应阵列智能天线（ＡｄａｐｔｉｖｅＡｒｒａｙＡｎｔｅｎｎａ） ,是一种起源于相控阵雷达的天线技术。自适应阵列智能天线利用基带数字信号处理技术 ,通过先进的算法处理 ,对基站的接收和发射波束进行自适应的赋形 ,从而达到降低干扰、增加容量、扩大覆盖和提高无线数据传输速率的目的。目前 ,自适应阵列智能天线已经成为智能天线发展的主流。本文主要介绍自适应阵列智能天线在３Ｇ中的应用 ,同时介绍了爱瑞通信公司 (ＡｒｒａｙＣｏｍｍＩｎｃ)的ＩｎｔｅｌｌｉＣｅｌｌ技术技术方案。１ 自适应阵列天线技术自适应阵列天线技术是近３０…     

一种时分单通道自适应天线的研究

提出了自适应天线系统的一种时分单通道接收机方案,针对HF三元阵列自适应零位天线系统,分析了其帧结构、采样周期、时隙及其与载波之间的关系.给出了直接利用采样数据计算相关矩阵的算法.解决了多通道接收机电路复杂,难以保证各通道性能一致的问题.模拟测试结果证明了该方案可对两个任意来向的干扰进行有效的抑制.     

LTE-A上行MIMO系统中空频编码及CM性能的研究

在LTE-A上行系统中,人们采用单载波频分多址接入（SC-FDMA）方案。SC-FDMA是一种具有与正交频分复用（OFDM）系统相似复杂度,立方度量（CM）低的单载波调制和频域均衡技术。首先介绍了LTE-A上行多输入输出（MIMO）系统架构,在此基础上研究资源块、调制方式和多天线空频编码（SFBC）对上行系统CM的影响。仿真结果证明,天线越多,其对系统CM影响越大,4天线发送系统中空频编码技术对系统CM值的影响占主体。     

Interference suppression with adaptive multipath control technique for broadband private wireless access systems

Proposed is an adaptive multipath control technique to suppress interference radiation from a transmitter to the non-target receivers for broadband private wireless access systems. In the proposed scheme, deep and wide creation techniques are employed in the adaptive array antenna to effectively use a limited number of antenna degrees of freedom under rich scattering indoor channel conditions. Computer simulation confirms that the proposed scheme is very effective in control of the transmit antenna directivity to suppress interference radiation, thereby the interference to the non-target receivers is largely reduced, and BER performance is greatly improved with low outage probability.     

基于大规模天线系统的多通道校准算法研究

文章首先详细地给出大规模天线系统技术优势,并详细给出宽带信号多通道校准基本原理和步骤;然后提出一种新的应用于大规模天线系统的多通道算法,算法实现性能能够将多路待校准通道准确按照参考通道进行校准拟合,并满足系统对多通道幅相一致性的指标要求。实测数据分析表明:多通道校准校准结果可以满足时延、幅度和相位指标要求,保证大规模天线系统的波束赋形和空分复用性能最优。     

Improved generalized spatial modulation via antenna selection

When a high spectral efficiency is needed, the cost of Euclidean distance‐based antenna selection for spatial modulation (EDAS‐SM) in terms of hardware, size, and computational complexity is significantly increased because of the large transmit antenna array required. In comparison, generalized spatial modulation (GSM) can match the spectral efficiency of EDAS‐SM, while using significantly fewer transmit antenna elements. However, the error performance of GSM is naturally limited because of the use of a predetermined and fixed set of transmit antenna combinations. By exploiting knowledge of the channel, the optimal set of transmit antenna combinations can be selected by maximizing the minimum Euclidean distance between transmit vectors. In this paper, an adaptive scheme for selection of the optimal set of transmit antenna combinations is proposed to improve the reliability of GSM. The computational overhead of the said scheme is relatively high; hence, a low‐complexity suboptimal scheme for selection of the set of transmit antenna combinations is further proposed. The improved GSM schemes address the spectral efficiency limitation of EDAS‐SM, while demonstrating superior error performance.     

Adaptive transmit antenna selection with pragmatic space-time trellis codes

We consider the problem of selecting a subset of transmit antennas in MIMO systems to minimize error probability when only partial channel information is available at the transmitter. An upper bound for error probability of space-time coded transmit antenna selection scheme conditioned on the channel state information is presented. Based on the performance analysis, a criterion of selecting a subset of available transmit antennas to minimize the upper bound on the PEP is proposed. In contrast to other transmit antenna selection schemes for uncoded transmission or with a fixed number of antennas within the selection subset in the literature, the proposed scheme can adaptively select both a variable number of transmit antennas and their corresponding space-time codes for transmission. Furthermore, we present pragmatic space-time trellis coding schemes for slow Rayleigh fading channels. The principal advantage of the schemes is that a single encoder and decoder can be used for systems with a variable number of transmit antennas. The performance of the pragmatic space-time codes with adaptive antenna selection and the effect of the imperfect channel estimation on performance are evaluated by simulations. It is shown that the adaptive selection offers considerable antenna selection gain relative to the antenna selection system with a fixed number of antennas within the selection subset     

结合波束形成与发射分集的闭环下行发射方案

多天线技术是提高下行发射性能的一种有效方法。波束形成(BF)和发射分集(TD)均通过使用多个天线来有效地改善系统性能并提高信道容量。该文提出了一种将BF和TD结合用于闭环通信系统的自适应下行发射方案, 它包括适合于慢变信道的分集阵列方法和适合于快变信道的波束形成阵列方法。基站可以根据实际的信道状况自适应地调整发射方法。文中详细地介绍了自适应方案的实现算法,并对算法的复杂度和适应环境进行了分析。仿真结果证明新方案可以同时获得BF增益和TD增益,在使系统的误比特率(BER)性能大幅提高的同时,增强了系统对信道变化的适应能力。     

Analysis of quasi-ML multiuser detection of DS/CDMA systems inasynchronous channels

We consider the quasi-maximum-likelihood (quasi-ML) detectors of the reverse link system that uses antenna arrays in asynchronous channels when the channel vector is time-invariant and time-varying. A channel vector estimation method based on eigendecomposition for time-invariant channels and its adaptive version suitable for the time-varying channels are also proposed. It is shown that the proposed quasi-ML detector can be regarded as a beamformer followed by a decorrelating filter and that the proposed system performs better than the conventional decorrelator scheme. It is also observed that the performance gain of the proposed scheme over the conventional decorrelator system increases as the numbers of active users and antenna arrays increase     

基于软件无线电架构的智能天线幅相校准

针对天线阵对多通道幅度和相位一致性的要求,在基于软件无线电(Software Defined Radio,SDR)架构的智能天线基础上提出了射频通道幅相测算和板级幅相测算相结合方案,具备幅相慢变特性的射频通道采用离线参数法,而板上多通道采用在线测算法,并采用星座旋转算法实现了相位校准.最后通过现场可编程门阵列(Field Programmable Gate Array,FPGA)模块仿真验证了该校准方法的正确性,并分析了系统误差来源及规避方法,为多通道系统幅相校准提供了工程化应用基础.     

A phase noise mitigation scheme for MIMO WLANs with spatially correlated and imperfectly estimated channels

Applying multiple input multiple output (MIMO) technique to OFDM-based wireless local area networks (WLANs) promises impressive high capacity and spectral efficiency compared with conventional systems. However, similar to SISO-OFDM, MIMO-OFDM suffers significant performance degradation due to the presence of phase noise. Many methods have been developed to mitigate phase noise for a single antenna system with perfect channel estimation, whereas none has been proposed for correlated MIMO-OFDM scenarios. Therefore, in this letter, by using the phase noise correlation function, a new phase noise mitigation scheme is proposed for the general M/sub T//spl times/M/sub R/ MIMO WLANs system with channel estimation errors. Numerical results show that, compared with conventional approaches, the proposed scheme achieves significant performance gain with high spectral efficiency, requiring few pilots, and is robust to spatial correlation and channel estimation errors, which makes it very attractive for practical applications.     

Control of peak sidelobe level in adaptive arrays

Adaptive beamforming techniques are now widely used to reject interference (jammer/clutter) signals in radar, communication, and sonar applications. In adaptive arrays using the sample matrix inversion (SMI) algorithm, inadequate estimation of the covariance matrix results in adaptive antenna patterns with high sidelobes and distorted mainbeams. In this paper, a method is proposed to precisely control the peak (rather than average) sidelobe level of adaptive array patterns. The proposed method is also generalized to adaptive array antennas with moderate bandwidth and large random amplitude and phase errors. Theoretical analysis and simulation results are provided to illustrate the performance of the method proposed