RPR网络的OPNET建模与性能测试

弹性分组环(RPR)集可靠性、高效性和经济性于一身,因此成为优化城域网中数据传输的首选技术.利用OP-NET网络仿真软件对RPR网络进行建模,并测试其端到端延时、节点吞吐量及公平性等关键性能,证明该模型的可靠性.     

混合STBC-VBLAST系统天线选择方案研究

研究表明MIMO系统中接收端SNR是一加权卡方随机变量,其权值为相应信道协方差逆阵的对角元素。为获得传输效率和传输可靠性间的折衷,利用协方差矩阵逆阵的对角元素,提出一种基于最小平均误码率（BER）的混合STBC-VBLAST发射天线选择方案。通过与传统无选择的VBLAST系统和有选择的VBLAST系统的BER和容量分别进行仿真比较,验证了所提混合STBC-VBLAST系统天线选择方案的优越性。     

无线网络优化平台的规划与建设

本文主要介绍无线网络优化平台的规划和建设方案,提出基于集中管理思路的无线网优平台架构,并对其中的无线参数管理系统的建设情况做介绍。     

差分LC滤波器在通信电路中的设计和应用

差分信号在无线通信系统链路中应用越来越广泛,模拟的差分LC滤波器可以有效抑制射中频电路中的带外谐波和噪声等无用信号。文章提出差分LC滤波器设计途径和单端LC滤波器简单的转换关系,介绍了射中频差分LC滤波器在无线通信系统中的一些应用问题。     

A Coding and Automatic Error-Correction Circuit Based on the Five-Particle Entangled State

In this paper, we discuss the concepts of quantum coding and error correction for a five-particle entangled state. Error correction can correct bit-reverse or phase-flip errors of one and two quantum states and is no longer limited to only one quantum state. We encode a single quantum state into a five-particle entangled state before being transferred to the sender. We designed an automatic error-correction circuit to correct errors caused by noise. We also simplify the design process for a multiple quantum error-correction circuit. We compare error-correction schemes for five and three entangled particles in terms of efficiency and capabilities. The results show that error-correction efficiency and fidelity are im- proved.     

Rate adaptive resource allocation in orthogonal frequency division multiple access system using multi‐objective immune algorithm

Rate adaptive downlink resource allocation in orthogonal frequency division multiple access system is a constraint optimization problem, which is to maximize the minimum data rate of the user subject to constraint that total power cannot exceed a given value. How to handle the constraint is a key issue for constrained optimization problem. Different with the available schemes on constraint handling, the proposed algorithm converts the constraint into an objective. Then, the resource allocation is combined into a multi‐objective optimization problem. An improved multi‐objective optimization algorithm based on artificial immune system is proposed to solve it. The simulation results show that, compared with previous schemes, the proposed algorithm performs remarkable improvement in sum capacity. Copyright © 2013 John Wiley & Sons, Ltd.     

Detecting Hot Road Mobility of Vehicular Ad Hoc Networks

Vehicular Ad Hoc Networks (VANETs) can provide value-added services to both drivers and passengers with on-board vehicular communication systems. Node mobility and volatile wireless connection in VANETs affect inter-contact time (T _I ) between mobile nodes, which greatly degrades the performance of vehicular applications. Nevertheless, the node spatial distribution in VANETs is another important factor especially in real applications. It positively affects the inter-contact time of vehicular nodes. By leveraging it, we can significantly improve the performance of data transmissions and inter-vehicle communication. To this end, we investigate the data collected from around 4,000 taxisin Shanghai and propose in this paper an efficient hot road mobility model. We find that most taxis distribute on some hot roads, which makes the node spatial distribution follow the power law. Based on this observation, we propose the concepts of indirect contact and heterogeneous inter-contact time (T _H ) to reveal how hot roads can change the distribution of inter-contact time. We find that the tail distribution of T _H also appears the power law, and both node spatial distribution and T _H distribution decay at least as the power law. We further propose a model for detecting vehicle mobility in hot roads, which can generates synthetic traces that captures both spatial and temporal features of nodes in VANETs.     

数字化PGC解调光纤水听器的动态范围

阐述了基于数字化PGC解调的光纤水听器基本原理,对该系统最大可测信号及最小可测信号进行了理论分析,得出了系统动态范围的主要决定因素。搭建光纤水听器系统,测试了光纤水听器系统的自噪声谱级,建立标准得到系统的最大可测信号。当带宽为63～1600Hz时,测得系统的动态范围高达108～120dB。     

10Gbit/s高T0无制冷分布反馈激光器

与折射率耦合分布的分布反馈（DFB）激光器相比,不管界面反射率是多少,增益耦合DFB激光器都能稳定地单纵模工作,而且具有高速、低啁啾的特性．本课题组用AlGaInAs/InP材料,采用增益耦合DFB结构,进行了单纵模激光器研发,并对器件特性进行了测试分析．     

构造嵌入式Linux系统

文中首先介绍了嵌入式Linux系统的优点及其广泛应用.然后针对构造一个Linux嵌入式操作系统所面临的问题作了具体深入的分析.这些问题具体包括如何精简内核以及系统启动过程的细致分析,如何为硬件编写驱动程序.