分组无线网的路由选择算法研究

探讨了分组无线网的分布式路由远择算法，分析了以往ＤＡＲＰＡ网中的ＤＡＲ算法存在的缺陷，提出了一种新的ＬＮＲ分布式路由选择算法，并在性能上与ＤＡＲ算法进行了比较。结果表明，由于ＬＮＲ算法克服了环路及无限计数问题，因而ＬＮＲ算法无论在选择最佳路由上，还是在总体开销上，都优于以往以ＤＡＲ为代表的分布式路由选择算法。     

移动通信系统中的f9算法的研究

移动通信中的f9算法是信令消息的完整性验证算法,它通过内核算法计算出信息的消息认证码,内核算法的安全性决定了f9算法的安全性。针对这个特性,提出了以IDEA为内核算法的f9算法,并与原内核为KASUMI的f9算法在加密速度上进行了比较。实验结果表明内核为IDEA的f9算法在加密速度上有了明显的提高。     

一种性能优越的Turbo码SOVA译码算法

MAP译码算法性能上是最优的,但是其复杂度也是十分高的,影响了硬件的实现,介绍了一种性能上接近于MAP译码算法,复杂度上有明显减少的译码算法,并且对其进行了完善,仿真结果表明对于二进制Turbo码,改进后的译码算法与MAP算法的译码性能更为接近。     

双三次卷积模板插值算法的FPGA实现

为了能在硬件上实现高质量、高效果的视频图像缩放、旋转等,文章研究分析了双三次插值算法的实现,对双三次插值计算进行离散化,得到相应的计算模板,简化计算过程。提出了一种在FPGA上实现双三次卷积模板算法的方法。实验结果表明:该算法的缩放效果优于双线性插值算法,略低于双三次插值算法,但计算性能上明显高于双三次插值算法。双三次卷积模板插值算法是一种能够在有限的资源上实现较好效果的插值算法。     

基于贪婪算法的系统级故障的概率诊断

概率诊断算法是系统级故障诊断研究的一个重要方面,本文在集团理论的基础上,利用贪婪算法中不同贪婪准则提出了四个概率诊断算法.通过对诊断算法进行仿真,分析比较了各算法的性能,每种算法在较少的测试数情况下,均表现出较高的诊断正确率,且时间复杂度不高.四种贪婪算法中贪婪算法一的性能最优,实验结果表明,相对于经典的概率诊断算法—Compete算法与Majority算法,相同条件下,在诊断正确率上贪婪算法一要远好于Majority算法,在时间复杂度上要好于Compete算法,综合性能上要优于此两种概率诊断算法.     

基于两点式数据关联算法的多机动目标跟踪

本文首先分析了两点式概率数据关联算法,在此基础上将其与交互式多模型算法结合起来提出了一种用于跟踪多机动目标的新算法.由于充分利用了两点式数据关联算法在关联精度和计算量上的优越性,所提出的新算法无论在跟踪精度方面,还是计算量上都有很大的改善.理论分析与仿真结果验证了该算法优于传统的交互式多模型联合数据关联算法.     

一种改进LMS算法的高速FPGA实现

通过将并行处理方法引入延时 LMS ( DLMS )算法,研究了一种新的并行延时 LMS (PDLMS)算法的FPGA实现。与DLMS算法相比,PDLMS算法具有更小的延时,更高的数据吞吐率,更快的收敛速度。使用Verilog HDL语言完成了该算法在硬件上的实现,同时给出了仿真结构,仿真验证了PDLMS算法比DLMS算法在性能上更具优越性。     

无线Mesh网络安全路由算法研究

从路由安全性的角度出发,对无线Mesh网络中的多径路由(MPR)算法和随机路由(SR)算法进行了研究.在分析这两种算法的思路、实现步骤和安全性的基础上,对MPR算法和SR算法进行了仿真.仿真结果表示SR算法在路由安全性能上优于MPR算法,但在网络时延性能上劣于MPR算法.     

一种改进的MCMC移动步骤的U粒子滤波算法

粒子退化是标准粒子滤波算法的主要缺陷。针对这一缺陷,提出了一种改进算法,在提出的具有MCMC移动步骤的U粒子滤波算法上进行性能分析,从样本产生和对MCMC移动步骤的使用两个方面对算法进行改进,减小了算法的计算量,提高算法的运算速度。仿真结果表明,改进后的算法大大减少了运算量,从一定程度上提高了运行效率。     

光纤传感系统改进相关算法的DSP实现

基于快速傅里叶变换改进了相关算法,证明了改进算法和传统算法在数学上的等效性。然后进行实验验证,在不同的数据长度上进行对比,表明该改进算法可以在DSP上高速完成相关运算,满足传感系统中对实时性的要求。     

Identification of the source of an interferer by comparison with known carriers using a single satellite

We describe a method for identifying the source of a satellite interferer using a single satellite. The technique relies on the fact that the strength of a carrier signal measured at the downlink station varies with time due to a number of factors, and we use a quantum‐inspired algorithm to compute a “signature” for a signal, which captures part of the pattern of variation that is a characteristic of the uplink antenna. We define a distance measure to numerically quantify the degree of similarity between two signatures, and by computing the distances between the signature for an interfering carrier and the signatures of the known carriers being relayed by the same satellite at the same time, we can identify the antenna that the interferer originated from, if a known carrier is being relayed from it. As a proof of concept, we evaluate the performance of the technique using a simple statistical model applied to measured carrier data.     

一种安全的纠错网络编码

该文利用消息空间的所有子空间上的一种度量,给出了一种安全的纠错网络编码。首先,此度量下的最小距离译码法可以纠正一定维数的错误。另外,在此编码方法下,当攻击者能窃听到的信道数目小于网络的最大流时,攻击者得不到关于信源的任何信息。最后,当攻击者能窃听网络中所有信道时,本文通过让信源和信宿共享一个随机数生成器和一个秘钥,进一步给出了能防此类强攻击者的安全纠错网络编码。     

Performance analysis by simulation of floating-gate MOSFETs applied on a bidirectional associative memory architecture

Floating-gate MOSFETs (FGMOSFETs) are devices that can be electrically programmable and have a non-volatile characteristic. This feature can be adopted to configure a basic cell performing as a variable resistance that can be applied in artificial neural networks as a synapse. Based on a simple model and considering the coupling coefficient of the structure as the gain of a voltage controlled voltage source, the electrical characteristics of a floating-gate MOSFET can be simulated in PSpice and an artificial neural net, such as the bidirectional associative memory (BAM), can be implemented. Therefore a performance analysis of the net may be done with different sets of threshold voltages for the FGMOSFETs configured as a CMOS inverter used as a synapse. The objective is to know pattern pairs in a bidirectional way. The result is a correlation matrix for the BAM as a function of an electrical parameter of the devices, which is directly related to the respective matrix calculated by the matrix dot product, using the method outlined by Kosko.     

多路径环境下电信流量模型研究

在下一代通信网络中,一个终端可同时拥有多个网络接口,在一对源、目的终端间存在多条可用路径。这为网络通信提供了一种全新的思路,即利用多条路径并发进行数据传输。针对多路径传输出现的问题,文章为多路径传输建立了流量模型,分析了多路径传输流媒体的优势,提出了＂流体带宽＂和＂流体调度＂的概念,并引入网络流理论计算了多路径环境下的目标流量。     

A quad-rotor system for driving and flying missions by tilting mechanism of rotors: From design to control

This article presents the hybrid design and control of a quad-rotor system called Flymobile. Flymobile is a combined system of a mobile robot and a quad-rotor system aimed to perform both flying and driving tasks. Flymobile performs flying tasks in the same way as conventional quad-rotor systems while the tilting mechanism of each rotor allows Flymobile to navigate in its terrain for a driving task. The body frame with rotors is implemented by a calibration process through a test-bed equipped with a force sensor. The triangular wheel frame is designed to mimic motions of a mobile robot with three passive wheels. Sensor data of a gyro and an accelerometer are filtered and used for controlling the attitude of the system. Focusing on a practical approach of implementing a hybrid system, a non model-based approach is applied to control Flymobile. Experimental studies are demonstrated to show the feasibility of performing both driving and flying missions.     

Virtual impedance control for a regional dynamic voltage restorer

A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented.     

Delay Analysis of All-Optical Packet-Switching Ring and Bus Communications Networks

We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing cross-connect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted ring or bus access methods. In this case, a packet's delay is known before it is fed into the network. This can be used to determine if a packet must be dropped (when its end-to-end delay requirement is not met) at the time it accesses the network. It also leads to better utilization of network capacity resources. We also derive the delay performance for networks under a store-and-forward network operation. We show these implementations to yield very close average end-to-end packet queueing delay performance. We note that a cross-connect network operation can yield a somewhat higher queueing delay variance levels. However, the mean queueing delay for all traffic flows are the same for a cross-connect network operation (under equal nodal traffic loading), while that in a store-and-forward network increases as the path length increases. For a ring network loaded by a uniform traffic matrix, the queueing delay incurred by 90% of the packets in a cross-connect network may be lower than that experienced in a store-and-forward network. We also study a store-and-forward network operation under a nodal round robin (fair queueing) scheduling policy. We show the variance performance of the packet queueing delay for such a network to be close to that exhibited by a cross-connect (all-optical) network.     

Ku波段上变频组件的设计

介绍了Ku波段上变频组件的设计与制作,整个组件由低相噪振荡器、滤波器、功分器、功率放大器、PIN开关、上变频器等部分组成。文章分别对一些主要部件进行了简要的理论分析,并给出微波电路的结构形式,最后给出样品的测试结果。     

X波段GaN HEMT内匹配器件

自主研制的GaN HEMT,栅源泄漏电流从1E-4A量级减小到了1E-6A量级,有效提高了栅漏击穿电压,改善了器件工作特性. 采用MIS结构制作了2.5mm栅宽GaN HEMT,测试频率为8GHz,漏源电压为33V时,器件连续波输出功率为18.2W,功率增益为7.6dB,峰值功率附加效率为43.0%. 2.5mm×4 GaN HEMT内匹配器件,测试频率8GHz,连续波输出功率64.5W,功率增益7.2dB,功率附加效率39%.     

Optimum crossing-point estimation of a sampled analog signal with a periodic carrier

The problem of estimating the crossing points of a continuous-time random process, represented by a sequence of uniformly spaced noisy samples, with a periodic analog carrier signal is of crucial importance in the implementation of pulse-width modulation (PWM) and other event-triggered sampling systems. In this paper, we formally approach this problem from a statistical signal processing perspective under a Bayesian framework. We derive the maximum a posteriori (MAP) estimator of the crossing point from a finite sequence of noisy observations, along with a close approximation based on minimum mean squared error (MMSE) considerations. We also study the Bayesian Cramér-Rao bound (CRB) on attainable mean square estimation error. Finally, simulations of a PWM scenario demonstrate that both the MAP and MMSE estimators approach the CRB and outperform several benchmark estimators. The MMSE is a particularly attractive solution as it offers a computationally efficient approximation to the MAP estimator.