强干扰下的波束形成

提出强干扰条件下等距线阵的波束形成方法。该方法将空间角度映射到数字频率,对阵列方向图的设计就等效于对FIR滤波器的零点设计。在强干扰方向形成零陷可采用零点修改法与零点增加法2种设计方法,由于该2种方法均会使波束主瓣方向略有改变,且对旁瓣的抑制能力有所下降,所以要设计方向图指向正确且对旁瓣电平有要求的方向图时需要进行迭代设计。仿真结果表明,该2种设计方法适用于强干扰条件下弱信号的接收。     

一种改进的稳健自适应波束形成算法

当快拍数较小时,自适应波束形成算法的性能将会降低,而对角加载算法是提高这类自适应波束形成算法稳健性的简单而有效的方法,但是至今没有一种比较有效的方法来确定对角加载值。本文提出了一种确定加载值的方法,这种方法在加载值和协方差矩阵的估计误差之间建立联系,它能够根据阵列的输出数据动态的调整加载值。计算机仿真证实了该算法的有效性。     

一种近场环境下的麦克风阵列语音增强方法

针对语音源位于阵列近场而干扰噪声源位于阵列远场的声学环境,本文提出了一种基于近场双自适应波束形成的麦克风阵列语音增强方法。该方法利用近场声波波前的特点,主通道采用最小方差无失真响应准则的近场优化波束形成器,辅助通道采用双自适应波束形成技术,从而有效地抑制了混响和噪声对语音信号的影响。仿真实验结果表明,在房间混响条件下,本文方法具有良好的噪声抑制性能。     

Multiuser beamforming based on max SINR for downlink spatial multiplexing MIMO

In this article, a method based on max signal interference noise ratio (SINR) criterion is proposed, to mitigate the interuser interference for downlink multiuser spatial multiplexing multi-input multi-output (MIMO) systems.Unlike the zero forcing (ZF) scheme in which the SNR is decreased when the interference is eliminated completely, max SINR method makes a compromise between noise and interuser interference.When the number of substreams is larger than the difference between the number of base station antennas and the sum of interference mobile station antennas, the ZF is infeasible.An existing coordinated TX-RX block diagonalization (COOR BD) method uses preprocessing at the receiver to cancel the interuser interference.However, it cannot obtain more receive diversity gain because of the preprocessing.Analysis and simulation show that the max SINR scheme has better performance than the ZF method.Moreover, when the ZF is infeasible, the max SINR scheme can obtain more receive diversity gain than COOR BD in the two-user case.     

一种改进的盲自适应波束形成算法

本文在最小二乘恒模（LSCMA）和梯度下降法（SDCMA）的基础上，提出了一种基于预解扩的判决反馈盲自适应波束形成算法，称为LS—SDCMA。本文分别在加性白高斯和多径衰落信道的环境中进行了仿真，仿真结果表明，本文提出的LS—SDCMA算法比传统的LSCMA、OCMA和SDCMA算法具有较强的抗多址干扰能力。     

无源雷达中多波束DBF的设计方法

论述了无源雷达中实现多波束数字波束的方法。阐明通道幅相误差的构成,指出幅相一致性对波束形成的影响,提供了校准通道和评估形成波束的实用方法。给出了在Champ-av3主板上实现多波束DBF的硬件框图和软件流程。     

基于天线波束成形的OFDMA系统的自适应资源分配

对正交频分复用接入系统在多用户多天线传输情况下的自适应资源分配策略进行了研究,提出了一种基于天线波束成形的,包括动态子载波分配、自适应调制、比特加载的无线资源分配方案.算法的优化设计目标是在满足总的恒定传输比特数和误比特率性能要求的情况下,使得系统总的发射功率最小.仿真结果表明,由于多天线阵列增益和多用户分集增益,系统整体性能得到了明显的优化.     

On Broadband Adaptive Beamforming in the Presence of Correlated Interferences

A novel approach of unitarily interpolated array MVDR （UIA-MVDR） is proposed, aiming at avoiding the signal cancellation caused by broadband signal-correlated interferences. UIA-MVDR belongs to the classic approaches of spectral averaging. However, it is distinguished from the conventional interpolated array MVDR （IA-MVDR） by two points： 1） It imposes a unitary constraint on the transform matrices. 2） It only optimizes the worst-case performance of array manifold approximation. As a result, the restriction on the order of Bessel function expansion is released, so that very accurate approximation can be achieved even in the case of small or middle arrays. Compared with many related approaches, UIA-MVDR destroys the correlation more completely and then achieves better performance. Its excellent performance in both correlated and uncorrelated broadband interferences suppression is confirmed via a n umber of numerical examples.     

认知中继网络中的鲁棒传输

In cognitive relay networks, the transmission of Secondary Users (SUs) suffers from the activity of Primary Users (PUs) and wireless channel fading. Therefore, how to achieve robust transmission for cognitive relay networks is a challenging task. In this paper, we propose a relaying transmission scheme which exploits robust beamforming at the physical layer and rateless codes at higher layers. We derive the optimal beamforming weight vector and analyze the performance of the proposed scheme when the channel estimation is not accurate between two SU nodes. We also study how the amount of channel information between SU and PU impacts the system performance. Simulation results validate our theoretical analysis and demonstrate that the proposed scheme can significantly enhance the system throughput.     

IRS辅助的SWIPT系统中基于能效优先的波束成形设计与优化

以智能反射面(intelligent reflecting surface,IRS)辅助的无线携能通信(simultaneous wireless information and power transfer,SWIPT)系统为背景,研究了该系统中基于能效优先的多天线发送端有源波束成形与IRS无源波束成形联合设计与优化方法。以最大化接收端的最小能效为优化目标,构造在发送端功率、接收端能量阈值、IRS相移等多约束下的非线性优化问题,用交替方向乘子法(alternating direction method of multipliers,ADMM)求解。采用Dinkelbach算法转化目标函数,通过奇异值分解(singular value decomposition,SVD)和半定松弛(semi-definite relaxation,SDR)得到发送端有源波束成形向量。采用SDR得到IRS相移矩阵与反射波束成形向量。结果表明,该系统显著降低了系统能量收集(energy harvesting,EH)接收端的能量阈值。当系统总电路功耗为−15 dBm时,所提方案的用户能效为300 KB/J。当IRS反射阵源数与发送天线数均为最大值时,系统可达最大能效。