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.     

一种基子自适应天线的OFDM自适应比特分配算法

本文提出了一种利用自适应天线阵列实现自适应OFDM系统的方案.该方案利用抽样矩阵求逆(SMI)算法对天线阵列进行最优权值的估计,并根据天线权值计算出的信噪比(SNR),在各个子载波上进行目适应的比特分配.仿真结果表明,与传统的OFDM系统相比,利用此方案实现的自适应OFDM系统,误码率性能可以得到有效的改善.     

一种基于自适应天线的OFDM自适应比特分配算法

本文提出了一种利用自适应天线阵列实现自适应OFDM系统的方案。该方案利用抽样矩阵求逆(SMI)算法对天线阵列进行最优权值的估计,并根据天线权值计算出的信噪比(SNR)。在各个子载波上进行自适应的比特分配。仿真结果表明。与传统的OFDM系统相比,利用此方案实现的自适应OFDM系统,误码率性能可以得到有效的改善。     

基于HFSS的智能天线自适应算法的研究

以3G基站系统智能天线阵列为研究对象,在研究了常用智能天线自适应算法的基础上,针对常用算法测向精度有限以及来波方向估计过程的复杂性等问题,通过在接收机的输出端引入阵列导向矢量信号,利用阵列导向矢量的特殊性质,得出了一种改进后的自适应算法。采用该算法的智能天线阵列,不仅具有较强的波束搜索能力和抗干扰性能,而且不存在复杂的来波方向估计过程。最后通过对8元直线型智能天线阵列的HFSS仿真实验,得出了SINR、驻波比、方向图等特性曲线,验证了该算法的可行性。     

一种新的用于DS/CDMA系统的多级盲空时多用户接收机

本文讨论的接收机是用于DS/CDMA系统的多级自适应阵列和串行干扰消除联合接收机(AA-SIC),介绍的接收机同时使用了空域和时域处理以及多用户联合检测技术.一般的联合接收机要使用RAKE单元,本文所讨论的接收机没有使用RAKE单元,而利用智能天线的自适应算法能起到分集接收的功能,不仅能抑制多址干扰信号,而且构成简便,计算时间较短,有利于实际应用.     

一种基于子阵列合成的DOA估计算法

在卫星通信中,由于星上资源有限,导致星载信号处理接收机的数目一般少于阵列天线的阵元数.在某些应用中需要在这样的条件下实现DOA估计:信号达波数大于星载信号处理接收机数目但是可能小于阵列天线的阵元数.实质上是要求能够用较少数量的接收机进行接收、处理含有较多阵元的阵列天线上的信号.针对这类应用要求,本文提出一种基于子阵列合成的DOA估计算法.通过子阵列输出协方差矩阵合成等效的大阵列输出协方差矩阵,基于等效大阵列输出协方差矩阵实现达波DOA超分辨率估计;讨论了子阵列天线选择优化问题.对算法性能进行了仿真验证,结果表明算法是有效的.     

天线罩对自适应阵列天线性能的影响分析

建立了可受变化干扰源激发的阵列天线和天线罩系统分析模型,分别通过阵列天线接收到的干扰源的辐射功率以及阵列榆入矩阵的相关矩阵特征值分布两种方案,对天线罩的影响效应进行了评估.结果表明,天线罩的存在对阵列天线的自适应性能明显降低.采用物理光学法分析了天线罩存在时天线阵的方向图,并利用闪烁瓣的观点对其结论进行了解释.     

导航卫星阵列天线的快速现场系统校准算法

阵列天线接收处理全球卫星导航信号时,由于天线和射频前端的非理想性,会在不同方向卫星信号中引入不同的载波相位偏差,从而破坏卫星导航接收机距离观测量准确性。针对此问题,提出了一种易实现的卫星导航阵列天线的快速现场系统校准算法。校准过程分为通道校准和天线校准：通过开机和周期进行的通道校准实现阵列天线接收射频前端的通道响应测量;通过与接收处理不同卫星基带数据的数字接收机配合,实现阵列天线的现场阵列流形矢量校准。仿真验证了所提校准算法的正确性和有效性。     

CDMA2000系统中移动台的智能天线结构与性能

鉴于移动台的复杂度和功率的局限,该文叙述了一种应用于移动台的智能天线结构,它采用自适应阵列与RAKE接收机相结合的结构,其中自适应算法使用归一化最小均分算法(N-LMS),我们结合cdma2000系统前向链路的特点进行系统仿真,结果表明移动台使用智能天线性能比使用单极天线有所提高,且性能的提高受移动台速率的影响。     

卫星导航接收机自适应阵仿真测试评估

卫星导航接收机自适应天线系统能够对消干扰,保证在射频干扰和敌方释放干扰存在的情况下正常提供导航定位功能.为了评估自适应天线的抗干扰能力,必须建立适当的测试环境和测试方法.提出的一种在暗室中进行自适应天线测试的方法,具有保密性好,保证测试环境和外界互不干扰等优点.给出了自行研制的一种导航接收机自适应天线的测试结果.     

HF零位天线系统及其算法

介绍了一种三元阵HF零位天线系统的设计。系统采用分时采样单通道检测技术代替传统的多通道检测技术，解决了困扰开环系统中通道失配的难题。对系统的关键技术：鞭环组合天线、检测通道、信号处理平台、分时采样技术进行了讨论。实验表明，利用MUSIC测向算法以及最小化干扰信号算法，系统能有效地抑制干扰。     

Turbo-BLAST系统中天线选择和功率分配算法

提出一种适用于Turbo-BLAST系统的自适应天线选择和功率分配算法,所提算法以误比特率为优化目标,并且考虑了信道估计误差的影响.在总功率约束条件下,采用所提算法进行天线选择和自适应功率分配,并利用软干扰抵消算法对接收信号进行迭代检测,以进一步改善系统性能.仿真结果表明:采用所提算法可以显著改善系统的误比特率性能.     

A Multiuser Detection Receiver Using Blind Antenna Array and Adaptive Parallel Interference Cancellation

In this paper, the problem of multiuser detection for synchronous code division multiple access systems in both additive white Gaussian noise and multipath channels is addressed. A new multiuser detection receiver that uses an adaptive blind array along with an adaptive parallel interference canceler is proposed. The replacement of a conventional antenna array with a two-dimensional RAKE receiver is also considered for frequency selective Rayleigh fading channels. By using a constrained optimization criterion along with the gradient-projection algorithm, a blind algorithm for the adaptation of the array response vector is proposed. The new algorithm is superior to a few typical blind algorithms in the literature in terms of both performance and computational complexity. The proposed receiver has the ability to cancel very strong multiple access interference coming from the same direction as the desired signal. Simulation results are presented to show the excellent performance of the proposed combination scheme in comparison to that of using either a multiuser detection or adaptive antenna arrays in a severe near-far situation.     

Blind adaptive multiuser detection for DS/SSMA communications withgeneralized random spreading

A new spreading scheme and an accompanying blind adaptive receiver structure are proposed for direct-sequence spread-spectrum multiple-access communications in a slowly-varying, frequency-selective fading channel. Each user's spreading sequence is given by the Kronecker product of a long-period pseudonoise (PN) sequence, which is accurately modeled by a random sequence, and a short-length deterministic signature code. This spreading scheme bridges the gap between pure PN spreading and pure short-code spreading schemes. It is shown that with this spreading scheme, the channel response to the desired signal component is easily estimated without relying on the spectral decomposition of the signal correlation matrix. With the estimate of the channel response, the receiver suppresses interference based on the maximum signal-to-interference ratio criterion. The blind adaptive receiver requires only coarse timing information and a priori knowledge of the desired user's PN sequence for adaptation. Numerical results show that the adaptive receiver significantly suppresses interference by successfully estimating the channel response and the interference statistics with a low computational complexity. An extension to spatio-temporal processing using an array antenna is also discussed     

Combining Orthogonal Space Time Block Codes with Adaptive Sub-group Antenna Encoding

An adaptive space time transmit diversity scheme with simple feedback is proposed for the next generation wireless communication systems. By combining orthogonal space time block codes with adaptive sub-group antenna encoding, this new diversity scheme can effectively exploit the diversity potential provided by multiple antenna arrays without introducing interference among the signals transmitted at different antennas. In order to reduce the amount of feedback information as well as the computational complexity, a new quadrant phase constraining method is introduced to formulate the feedback information. With simple operations at both the transmitter and the receiver, the new adaptive diversity scheme outperforms not only open loop space time block encoding techniques, but also some close loop transmit diversity techniques with the same amount of feedback.     

A RAKE receiver design for WCDMA FDD uplink with an RLS-based adaptive beamforming scheme

In this paper, we present a RAKE receiver design with adaptive antenna arrays for the wide-band code-division multiple-access (WCDMA) frequency-division duplexing (FDD) uplink. The RLS-based adaptive beamforming scheme is proposed and can be built with the existing one-dimensional RAKE receiver. We adaptively calculate the beamforming weight vector for each multipath of the desired user, and use maximum ratio combining (MRC) to combine each multipath signal in the demodulation process. Two matched filters based on the spreading waveforms are designed in our scheme for WCDMA FDD uplink application. The proposed scheme has the ability of suppressing strong multiuser access interference and the other types of interferers through spatial ing. The tracking capability of the proposed algorithm is demonstrated in the simulation results.     

基于LMS的自适应智能天线研究

利用智能天线可以有效地减少多径效应所带来的影响,同时可以对干扰信号起到删除和抑制的作用,最终达到降低接收端误码率的目的.为达到这一目的提高系统的性能,文中提出了基于LMS的自适应智能天线,首先介绍了自适应智能天线的基本原理;其次,对最小均方误差算法和自适应滤波器作了详细的分析;最后,对文中提出的LMS自适应处理算法进行...     

Adaptive MMSE receiver with beamforming for DS/CDMA systems

The minimum mean-squared error (MMSE) receiver is a linear filter which can suppress multiple access interference (MAI) effectively in direct-sequence code-division multiple-access (CDMA) communications. An antenna array is also an efficient scheme for suppressing MAI and improving the system performance. In this letter, we consider an adaptive MMSE receiver in conjunction with beamforming in CDMA systems employing an antenna array. The proposed structure is featured as a low complexity receiver, which adapts the MMSE filter coefficients and the beamforming weights simultaneously. However, it does require the channel state information and the direction of arrival (DOA) of the desired user signal. As a result, we propose two adaptation methods to perform joint channel estimation and signal detection without any training sequence. It is demonstrated that the two proposed methods achieve similar bit-error-rate performance. More importantly, their performance degradation compared with the case with perfect channel information is small.     

多源宽带干扰对多阵元GPS接收机干扰效能分析

近年广泛使用的多阵元自适应调零天线抗干扰技术,大幅降低了单个GPS干扰源的干扰效能,如何对其实施有效干扰成为导航对抗的研究热点之一。本文首先使用干扰-信号比阈值分析了多阵元接收机失效机制,并使用单源干扰对其抗干扰效能进行了检验;其次建立了多源宽带高功率压制干扰模型,最后采用数值仿真研究了多源宽带高功率压制模式下,干扰4阵元线性约束最小方差(LCMV)自适应调零算法GPS接收机的工作效率。实验表明,适当布置的多源宽带高功率压制模式可以有效提升对多阵元GPS系统的干扰效能。