基于差分和斜投影的信源DOA分步估计方法

提出一种色噪声背景下,同时存在独立、相关和相干信源的DOA分步估计方法.该算法利用常规谱估计算法估计独立和相关(非相干)信源,然后用差分方法排除掉协方差矩阵具有Toeplitz结构的噪声和独市源信息,在利用斜投影算子的方法去除相关信源后,对剩余的相干信源采用修正平滑算法恢复为满秩.该算法在提高阵列的信源过载能力的同时,可避免重复估计相关信源.计算机仿真结果证明了新算法的有效性和正确性.     

一种分簇无线传感器网络中的分布式信源编码算法

针对密集型无线传感器网络中信息存在大量冗余的问题,该文提出了一种适用于分簇无线传感网络的分布式信源编码算法.该算法以边信息作为初始参考信源,利用信源间的相关性来决定各信源的编码顺序和参考信源,然后由各信源相对于参考信源进行相关编码,接收端则根据编码顺序和参考信源进行相关译码.该文同时针对模值编码的方式,给出了一种低复杂度的译码算法.理论分析和仿真结果表明,将该算法应用于分簇路由协议中可以有效地降低节点的发送比特数,从而降低网络的能耗以延长网络寿命.     

基于虚拟阵列改进MUSIC算法的相干信源DoA估计

受多径传输环境的影响,在智能天线测向研究中,必须考虑相干信源的存在.针对相干信源的波达方向(Direction of Arrival,DoA)估计问题,提出了一种基于虚拟阵列平移的改进MUSIC算法.仿真结果表明:在相干信源入射角度差异很小(约5°)的情况下,该算法依然能准确地估计;同时,该算法不损失阵列孔径,最多可估...     

混合信源背景下的DOA估计分步改进算法

信号在传输过程中会产生多径和电磁干扰,到达天线阵列后会同时存在非相干和相干信源,针对这种情况,文中提出了一种分步估计到达角的改进算法。该算法首先利用MUSIC算法估计非相干信源的到达角,然后在信号协方差矩阵中分离出相干信源的协方差矩阵,只对相干信源进行空间平滑估计出相干信源到达角。相比传统空间平滑算法,该算法在保持良好到达角分辨力的同时,减小了对天线阵列数的要求,在低信噪比时拥有更精确的估计能力。     

具有纠错能力的小波图像混合编码

小波图像压缩算法SPIHT的提出使图像压缩编码技术大大前进了一步.但该算法在噪声信道环境下性能将大打折扣.本文提出了一种基于SPIHT的信源信道混合编码算法,利用而不是改变嵌入式码流的特点,以灵活可变的方式在完成信源编码的同时完成信道编码,大大提高了SPIHT算法抵御干扰的能力,为该算法进入实用化创造了条件.     

基于特征矢量稀疏重构的欠定DOA估计算法

针对信源数多于阵元数,阵列测向欠定问题,利用最小冗余线阵的阵列扩展能力,以较少的阵元获得较大的阵列孔径,同时将最小冗余线阵与压缩感知理论相结合,提出一种基于特征矢量稀疏重构的欠定DOA估计算法.所提算法能以较少的阵元数估计更多信源的来波方位,具有信源过载能力,同时能降低稀疏重构运算的复杂度,增强了算法的鲁棒性、精确性,性能优于MUSIC算法,实验结果表明该方法是有效的.     

一种信源个数与波达方向联合估计的新算法

针对多级维纳滤波器(MSWF)用于子空间估计时信号特征矢量泄漏到噪声子空间的问题,提出了一种新的信号子空间估计算法,该算法不需要训练信号和信源个数的先验知识.随后,给出了一种信源个数的后判断方法,最终完成信源个数及方向的同时估计.整个算法不需要协方差矩阵的计算和特征值的分解,具有较低的计算复杂度.在均匀线阵且信号互不相关情况下,改进后的算法用于波达方向估计时拥有与基于特征分解方法近似的性能.仿真结果验证了该方法的有效性.     

一种未知信源数的高分辨DOA估计算法

提出了一种未知信源数的高分辨 DOA 估计算法。该算法在未知信源数的情况下,利用线性预测(LP)法或 Pisarenko 法与 ASPECT 技术相结合来实现高分辨谱估计。该算法在消除 LP 法或 Pisarenko 法 DOA 估计中存在的伪峰的同时可判断出入射信源数,明显减小 DOA 估计算法的运算量,并可提高谱分辨力。计算机仿真结果证明了新算法理论的正确性和有效性。     

混合信号情况下信源数与DOA联合估计算法

针对非相关信源与相干信源共存情况,提出了一种基于矩阵重构的信源数与波达方向（direction of arrival,DOA）联合估计算法.该算法首先利用特征值的二阶统计量（second order statistic of eigenvalues,SORTE）法和子空间旋转不变技术（estimated signal parameter via rotational invariance techniques,ESPRIT）实现非相关信源数与DOA估计;然后基于空间差分法消除非相关信号并构造新矩阵,利用构造矩阵进行前向空间平滑,实现对相干信源解相干;最后利用SORTE法检测相干信源数,结合求根多重信号分类（multiple signal classification,MUSIC）算法估计相干信源DOA.与传统的差分平滑方法相比,该算法在可估计信源数与低信噪比情况下DOA估计性能等方面优于传统算法.数值仿真实验结果验证了该算法的有效性.     

基于混沌密钥控制的联合信源信道与安全算术码编译码算法

该文针对深空通信、移动通信等资源受限网络中的信息有效性、可靠性和安全性传输,提出一种基于混沌密钥控制的联合信源信道与安全算术码编译码算法。该算法在编码端通过混沌映射1控制在算术码内嵌入多个禁用符号,将信道编码检错与密码流的扰乱相结合;同时,通过混沌映射2控制信源符号的算术编码,将信源编码与信息安全相结合,实现了联合信源信道与信息安全编译码。实验结果表明,该算法与现有的同类算法相比,当误包率为10-3时,改善编译码性能0.4 dB,同时增强了可靠性和安全性。     

一种用于ATM网中ABR多点对点连接的拥塞控制算法

ATM网中ABR多点对点连接的拥塞控制算法的研究目前尚处于起步阶段。已有的研究成果都集中于将原来点对点连接的控制算法移植到多点对点环境中来,尽管这可以方便地实现基于信源的公平性,但却不可避免地造成各ABR连接之间的带宽分配不公平。本文研究了基于VC／信源的公平性准则下拥塞控制算法的特点,首次提出了这类算法的设计原则,并给出了一种具体的拥塞控制算法。仿真结果表明,该算法不仅能实现基于VC／信源的公平性,而且在收敛速度、链路利用率等其它方面也具有良好性能。     

一种类图转化为关系数据库的自适应算法研究

提出了一种将类图转化为关系数据库RDBS的算法,首先使用Rational Rose工具创建类图,并使用Java语言对其进行描述;其次,将源代码文本作为算法执行,通过特定算法比较“ClaSS”,“attribute”和“relation”等关键字,区分出类、属性和关系;在完成数据库表的名称、属性字段的类型及大小等设置描述后,在MYSQL数据库中执行该算法,生成SQL命令创建数据库和表。这种算法能减少类图与关系数据库之间转化的出错概率和时间。     

自相似业务下资源分配研究

重点研究了排队系统中自相似业务带宽分配和接纳控制.根据分形布朗运动包络过程推导出了有效带宽的计算公式,并且推导出了考虑信源内增益和信源间增益的接纳控制算法.通过仿真研究了有效带宽随缓存区、Hurst系数的变化关系,接纳域随缓存区、Hurst系数的变化关系.证明了基于FBM下的资源分配比传统的模型更有效.     

A universal data compression system

A universal data compression algorithm is described which is capable of compressing long strings generated by a "finitely generated" source, with a near optimum per symbol length without prior knowledge of the source. This class of sources may be viewed as a generalization of Markov sources to random fields. Moreover, the algorithm does not require a working storage much larger than that needed to describe the source generating parameters.     

Robust sound localization in 0.18 /spl mu/m CMOS

This paper presents a hardware implementation of a sound localization algorithm that localizes a single sound source by using the information gathered by two separated microphones. This is achieved through estimating the time delay of arrival (TDOA) of sound at the two microphones. We have used a TDOA algorithm known as the "phase transform" to minimize the effects of reverberations and noise from the environment. Simplifications to the chosen TDOA algorithm were made in order to replace complex operations, such as the cosine function, with less expensive ones, such as iterative additions. The custom digital signal processor implementing this algorithm was designed in a 0.18-/spl mu/m CMOS process and tested successfully. The test chip is capable of localizing the direction of a sound source within 2.2/spl deg/ of accuracy, utilizing approximately 30 mW of power and 6.25 mm/sup 2/ of silicon area.     

一种基于虚拟墙的射线跟踪法*

针对现有射线跟踪算法效率低下的问题,利用虚拟源思想,设计了一种基于虚拟墙的射线跟踪算法。首先,通过将处于同一平面的墙面合并为"虚拟墙",降低了算法搜索过程中墙面的遍历次数。在此基础上,通过设计"透光区"、"光扇区"等有效性判决条件,完成节点有效性的判决,避免了无效节点的混入,减少了计算复杂度。最后,利用深度优先搜索算法完成虚拟源树状结构的建立,无须重复遍历即可获得发射点到接收点的全部有效路径。仿真结果表明,该算法路径损耗的预测精度随着树遍历深度的增加而提高,同时降低了算法复杂度。     

Maximum-likelihood transmission image reconstruction for overlapping transmission beams

In many transmission imaging geometries, the transmitted "beams" of photons overlap on the detector, such that a detector element may record photons that originated in different sources or source locations and thus traversed different paths through the object. Examples include systems based on scanning line sources or on multiple parallel rod sources. The overlap of these beams has been disregarded by both conventional analytical reconstruction methods as well as by previous statistical reconstruction methods. We propose a new algorithm for statistical image reconstruction of attenuation maps that explicitly accounts for overlapping beams in transmission scans. The algorithm is guaranteed to monotonically increase the objective function at each iteration. The availability of this algorithm enables the possibility of deliberately increasing the beam overlap so as to increase count rates. Simulated single photon emission tomography transmission scans based on a multiple line source array demonstrate that the proposed method yields improved resolution/noise tradeoffs relative to "conventional" reconstruction algorithms, both statistical and nonstatistical.     

An ASIC design and formal analysis of a novel pipelined and parallel sorting accelerator

Sorting, which is widely used in different areas such as database systems, IP routing, bio informatics, and cognitive-processing-based applications, imposes considerable overhead on computing resources. Therefore, an efficient on-chip sorting accelerator may significantly enhance real-time decision-making in such applications. In this paper we introduce a novel pipelined and parallel sorting algorithm with streaming I/O, with the time, logic, and memory complexity of O(n), , and O(n), respectively. We present a formal analysis to prove the correctness of this algorithm. We then model, verify, and synthesize this unconditional algorithm (in the TSMC 0.13 micron technology) for 4k-word clusters as an ASIC accelerating engine. More specifically, our implementation with 3969-word multiple-bank memory, 63 word-size comparators, 64 word-size multiplexers, and 63 word-size registers only requires some 8k clock cycles to sort an arbitrary 3969-word long array of random data, which arrive at the sorter and also depart it one item at a time.     

适于斜视FM-CW SAR系统改进的距离-多普勒算法

"停-走"模式是目前脉冲SAR信号处理和理论分析的基础,FM-CW SAR由于其大的脉冲重复周期和100%的占空比,恶化了接收脉冲的畸变。文中分析了当天线斜视角增大时,导致传统距离-多普勒算法性能下降的主要误差来源,对FM-CW SAR的信号处理问题进行深入研究,提出了改进的适合斜视FM-CW SAR大扫频周期的距离-多普勒算法。通过理论推导及仿真实验,验证了改进模型和算法的可行性与正确性。     

Analysis of modified "Bussgang" algorithms (MBAs) for channel equalization

In previous papers, we introduced two modified "Bussgang" algorithms (MBAs) for blind-channel equalization based on Bayesian iterative estimation of the source sequence. They were developed in order to reduce the computational complexity of the original "Bussgang" algorithm as well as to make it more flexible by introducing a kind of source adaptivity. However, the previous work relied on some heuristic findings, validated by a series of computer-based experiments. The aim of this paper is to present a theoretical investigation of some particular aspects of the adapting equations, namely, the steady-state conditions, in order to ameliorate the performances of the MBAs and to better explain their numerical behavior.