A comparative study of heuristic algorithms: GA and UMDA in spatially multiplexed communication systems

A performance comparison of genetic algorithm (GA) and the univariate marginal distribution algorithm (UMDA) as decoders in multiple input multiple output (MIMO) communication system is presented in this paper. While the optimal maximum likelihood (ML) decoder using an exhaustive search method is prohibitively complex, simulation results show that the GA and UMDA optimized MIMO detection algorithms result in near optimal bit error rate (BER) performance with significantly reduced computational complexity. The results also suggest that the heuristic based MIMO detection outperforms the vertical bell labs layered space time (VBLAST) detector without severely increasing the detection complexity. The performance of UMDA is found to be superior to that of GA in terms of computational complexity and the BER performance.     

基于可配置型K-Best的MIMO信号检测器

为减少高速通信系统中硬件资源的消耗,设计一种应用于MIMO-OFDM无线通信系统中的高速信号检测器,根据可重构设计的需求,提出一种简化K-BEST（SKB）MIMO信号检测算法,介绍可配置型硬件结构,并采用Xilinx Vertex-4 FPGA平台加以实现。仿真实验结果表明,该检测器的最高数据吞吐率可达2 Gb/s,并能针对不同星座调制信号（如QPSK,16-QAM）进行检测。     

A novel turbo-MIMO transceiver

A novel BLAST transceiver named turbo-like BLAST(TLBLAST) for MIMO communications is proposed,which combines the characteristics of HBLAST and VBLAST with the structure of turbo encoder. The high data rate transmission can be implemented and in each transmitted antenna,different encode schemes can be used to supply different protection levels. The system performance is improved effectively through serially concatenating a soft input soft output(SISO) detector and decoder by iterative process with comparable...     

基于元学习的短波MIMO信号检测

针对短波场景下已有的MIMO检测算法性能不佳或复杂度太高的问题,提出一种基于元学习的MIMO检测方法MetaMMNet.将不同的信道矩阵下的MIMO检测看作为独立的任务,通过对大量不同任务的学习使得模型获得对于不同信道矩阵的泛化能力,能够快速适应变化的信道矩阵.在4 QAM、16 QAM和64 QAM调制方式下进行仿真...     

MIMO链路ad hoc网络传输调度算法

针对MIMO链路ad hoc网络中已有传输调度算法未充分利用MIMO空间复用能力的问题,提出了一种新的传输调度算法.该算法通过考虑MIMO的多流接收能力而有效地减小了调度帧长,通过合理安排节点分配顺序使得节点分配的数据流比较平均,同时,该算法通过允许节点发送多个数据流而高效利用了MIMO的空间复用能力.推导分析了传输调度算法的通过量和时延性能,结果表明,与已有算法相比,采用文中算法可以提高网络的通过量,减小网络的平均时延和最大时延.     

Transmission scheduling algorithm for MIMO link ad hoc networks

Most reported works on transmission scheduling algorithm for multiple input multiple output (MIMO) link ad hoc networks do not fully exploit the spatial multiplexing potential inherent to multiple an-tennas system.In this paper,a novel transmission scheduling algorithm is proposed to further enhance the performance of MIMO link ad hoc networks.By utilizing the MIMO multi-stream reception capabilities and ordering the nodes’ allocation sequence,the proposed algorithm can dramatically shorten the scheduling frame length and more evenly distribute the data streams allocated to the network nodes.Meanwhile,allowing the nodes to transmit multiple streams in a slot,the algorithm can fully exploit the MIMO spatial multiplexing potential.Additionally,we give the theoretical analysis to quantify the throughput and delay performance with respect to this scheme.Numerical results demonstrate that the proposed algorithm can efficiently enhance the network throughput and reduce the average and maximum delay.     

MIMO-MC-CDMA系统分层空时非线性预编码

针对垂直分层空时方案（VBLAST）传统检测存在误层传输效应及复杂度高的问题,提出了一种多用户MIMO-MC-CDMA下行链路系统中基于QR分解的VBLAST非线性模代数预编码算法,该算法首先采用QR分解获得预编码矩阵,然后在发射端MC-CDMA子载波信道间进行非线性模代数THP预编码,可以有效地消除分层空时码的误层传输效应。在接收端采用迫零与最小均方误差准则,降低了下行接收机的复杂度。仿真结果表明,提出的算法比传统检测算法有效改善了系统的误码性能。     

基于信道分析的动态可重构MIMO检测器

在多输入多输出(MIMO)系统中分析信道增益对信号检测性能的影响,提出一种基于信道分析的智能MIMO信号检测算法,根据各对天线间的信道增益动态调整子节点扩展数,在检测性能接近最大似然算法性能的前提下,该算法比传统K-best算法减少54%的子节点扩展数。基于该算法设计并实现的动态可重构的超大规模集成电路MIMO检测器支持4×4天线阵列、QPSK/16-QAM调制信号,数据吞吐率达到800 Mb/s。     

Joint direction of arrival estimation and array calibration for coprime MIMO radar

Compared to large-scale MIMO radar, coprime MIMO radar can achieve approximate estimation performance with reduced antenna number. In this paper, joint direction of arrival (DOA) estimation and array calibration for coprime multiple-input multiple-output (MIMO) radar is considered, and an iterative method for the estimations of DOA and array gain-phase errors is proposed. Based on the received data structure of coprime MIMO radar, trilinear decomposition is firstly adopted to obtain the estimations of transmit and receive direction matrices, which are perturbated by the gain-phase errors. Through equation transformation, the un-perturbated direction matrices and gain-phase errors can be iteratively updated based on Least squares (LS). Finally, the unique DOA estimation is determined from the intersection of transmit and receive direction matrices. The proposed algorithm achieves better DOA estimation and array calibration performance than other methods including estimation of signal parameters via rotational invariance techniques (ESPRIT)-like algorithm, multiple signal classification (MUSIC)-like algorithm and joint angle and array gain-phase error estimation (JAAGE) method, and it performs close to the method with ideal arrays. Multiple simulation results verify the algorithmic effectiveness of the proposed method.     

基于颜色分量补偿的交通标志图像预处理

为提高图像预处理的效果,提出了一种基于颜色信息的颜色分量补偿预处理方法。该方法首先将实景图像分成RGB三个分量,根据要提取的交通标志颜色选择处理分量。接着对选择分量进行阈值处理实现候选标志与背景的粗分割。然后用阈值化的色彩分量替代原图中的对应分量重构为一幅新的彩色图像。最后通过颜色提取对重构图像进行处理以提取候选标志区域。实验表明,采用该方法进行交通标志的预处理,提高了交通标志检测时标志定位和形状检测步骤的准确度和速度,为交通标志预处理提供了一种可行的解决方案。     

基于增强蚁群优化的海量规模MIMO系统快速检测算法

大规模MIMO系统的符号向量检测算法计算复杂度较高,对此结合粒子群优化与蚁群优化提出一种低计算复杂度的海量规模MIMO系统快速检测算法。首先,推导出一种新的概率搜索模型,将基于距离的蚁群搜索与基于速度的粒子搜索结合;然后,将ACO距离指标与PSO的方向、速度指标结合生成一种新的概率指标,将ACO的信息素更新步骤变为PSO速度的更新;最终,将MIMO检测问题建模为路径寻找问题,寻找MIMO符号检测问题的次优解。对比仿真实验结果表明,本算法的检测性能优于部分传统算法以及其他新颖的MIMO检测算法,在获得与最大似然估计检测法接近的误码率性能下,具有极快的计算速度,适用于海量规模的MIMO系统。     

双通道Faster R-CNN在RGB-D手部检测中的应用

在人机交互、手语识别等大量与人手有关的视觉任务中,手部检测是极为重要的一个预处理阶段。随着RGB-D数据采集设备的发展,额外提供的深度数据能够与传统使用的彩色数据互相补充以提供更强的特征表达。此外,传统的检测方法由于使用肤色、HOG等手工设计的特征,不能对手部进行很好的表达。而基于深度学习的检测方法通过从数据中自动学习有效的特征避免了这个问题。为了结合RGB-D数据和深度学习技术的优点,提出了一种融合彩色和深度数据的双通道 Faster R-CNN检测框架。该方法在原有Faster R-CNN检测框架的基础上,增加了Depth通道信息,并在特征层面上将其与RGB通道信息进行融合。实验结果表明,所提方法在性能上比仅采用RGB或在数据层面上融合的Faster R-CNN框架有明显优势。因此,该方法能有效融合来自彩色和深度通道的数据,以提升手部检测性能。     

一种用于秩损信道下的MIMO检测算法

无线MIMO信道中由于天线相关性或者特殊的散射体结构, 会发生信道矩阵秩损现象, 从而导致传统的QRD-M算法无法直接应用。针对此问题, 首先利用信道规则化算法对信道矩阵进行扩展来解决秩损问题, 然而该预处理过程又会带来新的检测干扰, 通过采用一种改进的QRD-M检测算法来减小此干扰带来的影响。与传统QRD-M算法每层只保留M个节点不同, 改进的QRD-M检测算法将权值大于第M个节点且差值在某个阈值范围内的所有节点都保留下来, 并对阈值大小的选取进行了理论分析。仿真结果表明, 该算法能够在取较小M值下, 仍能获得较优的检测性能。     

Genetic algorithms with applications in wireless communications

Genetic algorithms (GAs) are known to locate the global optimal solution provided sufficient population and/or generation is used. Practically, a near-optimal satisfactory result can be found by Gas with a limited number of generations. In wireless communications, the exhaustive searching approach is widely applied to many techniques, such as maximum likelihood decoding (MLD) and distance spectrum (DS) techniques. The complexity of the exhaustive searching approach in the MLD or the DS technique is exponential in the number of transmit antennas and the size of the signal constellation for the multiple-input multiple-output (MIMO) communication systems. If a large number of antennas and a large size of signal constellations, e.g. PSK and QAM, are employed in the MIMO systems, the exhaustive searching approach becomes impractical and time consuming. In this paper, the GAs are applied to the MLD and DS techniques to provide a near-optimal performance with a reduced computational complexity for the MIMO systems. Two different GA-based efficient searching approaches are proposed for the MLD and DS techniques, respectively. The first proposed approach is based on a GA with sharing function method, which is employed to locate the multiple solutions of the distance spectrum for the Space-time Trellis Coded Orthogonal Frequency Division Multiplexing (STTC-OFDM) systems. The second approach is the GA-based MLD that attempts to find the closest point to the transmitted signal. The proposed approach can return a satisfactory result with a good initial signal vector provided to the GA. Through simulation results, it is shown that the proposed GA-based efficient searching approaches can achieve near-optimal performance, but with a lower searching complexity comparing with the original MLD and DS techniques for the MIMO systems.     

Simplified MMSE Detectors for Turbo Receiver in BICM MIMO Systems

In this article, two methods adopting simplified minimum mean square error (MMSE) filter with soft parallel interference cancellation (SPIC) are discussed for turbo receivers in bit interleaved coded modulation (BICM) multiple-input multiple-output (MIMO) systems. The proposed methods are utilized in the non-first iterative process of turbo receiver to suppress residual interference and noise. By modeling the components of residual interference after SPIC plus the noise as uncorrelated Gaussian random variables, the matrix inverse for weighting vector of conventional MMSE becomes unnecessary. Thus the complexity can be greatly reduced with only slight performance deterioration. By introducing optimal ordering to SPIC, performance gap between simplified MMSE and conventional MMSE further narrows. Monte Carlo simulation results confirm that the proposed algorithms can achieve almost the same performance as the conventional MMSE SPIC in various MIMO configurations, but with much lower computational complexity.     

极化MIMO雷达隐身目标检测性能研究*

多输入多输出(MIMO)雷达使用了远距分布的阵元,它利用了信号的空间分集增益来获取更多的目标信息。极化是另一种可以提高雷达系统性能的分集方式。当应对隐身目标时,传统的极化雷达在某些观测角度会遭受到较大的目标雷达截面积(RCS)衰减,而无法获得较好的检测性能。而在一个雷达系统中同时利用这两种分集增益,可以得到一种比传统极化雷达更具优势的新雷达检测系统——极化统计MIMO雷达,它可以更好地应对隐身目标检测。给出了相应的模型,并推导出了该雷达系统的检测性能解析式。将其与传统相控阵及非极化统计MIMO雷达比较,可以看到极化统计MIMO雷达的检测性能更佳。联系到隐身目标的特性,极化MIMO雷达的检测器特性应对它时具有显著优势。最后,以上方法通过仿真得到了验证。     

Target models and waveform design for detection in MIMO radar

In this paper,we propose a general target model for multiple-input multiple-output(MIMO)radar.Two types of targets are presented.For each type of target,we develop a corresponding optimum waveform designing method to optimize detection performance.Based on Chernof-Stein lemma,we use relative entropy as the performance measure.We show that the optimum waveform designing method can obtain better detection performance than traditional orthogonal waveform designing method.     

改进的混合多输入多输出系统收发方案

为在频谱利用率和可靠性之间取得折中,提出一种高效低复杂度的发射接收方案,将空间复用和空间分集相结合,形成一个STBC-VBLAST混合编码的多输入多输出系统。利用线性疏散码的结构特点,在发射端以等效的垂直分层空时码子层发送信号,接收端使用基于排序的QR分解的连续干扰抵消的算法进行译码,同样可以获得较好的复用和分集增益。仿真结果表明,该方案的误码率性能优于其他检测方案,可降低计算复杂度。     

Dual tree complex wavelet transform approach to copy-rotate-move forgery detection

As a common scheme of image tampering,copy-move forgery plays an important role in image forgery committee.Although several blind methods aimed at detecting replicated regions have been proposed,these methods cannot detect the rotation changes in the duplicated areas efciently.In this paper,a new forensic method is presented to detect the replicated areas rotated by arbitrary angles,even by JPEG compression.To achieve this,overlapping blocks of pixels are decomposed using dual tree complex wavelet transform(DTCWT),and then channel energies are extracted from each subband at each decomposition level using the L1norm.Finally,the anisotropic rotationally invariant features are extracted using magnitudes of discrete Fourier transform for these channel energies.The implementation procedure of the proposed method is described in detail.Extensive experimental results,including a comparative evaluation with existing methods and the special applications in practice,are also presented to demonstrate the robustness and efectiveness of the proposed method.