ANALYSIS OF A CUMULANT-BASED 2D-RAKE RECEIVER FOR CDMA SYSTEM OVER FREQUENCY-SELECTIVE FADING CHANNELS

Code divisionmultipleaccess (CDMA )isaspread spectrummultipleaccessschemethatisex pectedtogainasignificantshareofthecellularmar ket.CDMAhasseveralattractivepropertiesforper sonalcommunications.Andifallmobileradiosig nalsarrivingatthebasestationaresynchronizedtowithinafraction ,thesynchronousCDMA (S CD MA)systemscanenhancethebandwidthefficiencytoa greaterdegreebyemployingorthogonalcodewords.However,S CDMAsystemshavefunda mentaldifficultieswhenutilizedinafrequency se lectivefadingenviron…     

A Solution Model to Protect Mobile Agents Against Malicious Host Attack

Within an agent server, the model introduces a trusted third party entity called Secure Service Station(SSS). The SSS is a non-hardware component and is intended to prevent most attacks performed by malicioushosts, by providing mechanisms that ensure attack detection and provide integrity to mobile agents. This noble technique involves encapsulating partial results obtained on each intermediate host and binding these results together using a hash function, thus forming a strong bonded chain that cannot be compromised. An analytical model to explore the system performance was also developed.     

AN OPTIMIZED SCHEME FOR FAST HANDOFF IN IP-BASED CDMA WIRELESS COMMUNICATION NETWORKS

IntroductionMobility as an essential characteristic of wire-less network has received considerable attention inrecent years.A number of system- specific solu-tions have been developed for2 G( such as GSM)and 3G( such as UMTS) wireles networks.Fromthe Internetpointofview these solutions can be re-garded as layer- 2 solutions for wireless access net-works working transparently to the layer- 3 ( IPlayer) [1] .The evolution of wireless network is be-ing strongly influenced by mainly two compo…     

多码CDMA ALOHA系统及性能分析

提出了一种基于ALOHA和多码CDMA技术的多码CDMA ALOHA系统，用以支持多速率数据通信．分析了该系统在高斯噪声信道的吞吐量性能并进行了仿真．仿真和分析结果表明，由于综合了ALOHA和多码CDMA技术的优点，多码CDMA ALOHA系统能支持多速率数据业务且具有较好的性能。     

基于CORS的手机移动终端定位系统的设计

分析了高精度手机移动终端定位系统建立的必要性和可行性;提出了一种提高手机移动终端定位精度的实现方法;阐述了基于CORS的手机移动终端定位系统的基本内容和结构框架,通过手机解算和服务器解算两种模式进行了实现。     

Development of 2D hybrid equilibrium elements in large increment method

As a force-based finite element method (FEM), large increment method (LIM) has been developed in recent years. It has been shown that LIM provided prominent advantage of parallel computation with high efficiency and low time consumption for member structural system. To fully utilize its advantage in parallel computation, it is the time to extend LIM to 2D and 3D continua analysis. In this paper, a 2D finite element library with the capability of modeling arbitrary configurations is developed. Some illustrative numerical examples are solved by using the proposed library; the obtained results are compared with those obtained from both traditional displacement-based FEM and analytical solutions, which has clearly shown the advantages of LIM.     

基于手机定位的交通OD数据获取技术

居民出行OD数据是交通规划中最重要的基础资料之一。传统的利用纸和笔、电话调查以及路边询问等调查方式虽然简单,但存在较大局限性。随着信息技术、移动技术等的发展,手机信息和定位技术应用于交通数据采集是研究的热点之一。在CDMA通信网络和gpsOne手机定位技术的基础上,对出行者进行连续位置跟踪,通过数据处理提取出行者的起讫点位置信息,再结合已有交通区划分,根据点与多边形关系的算法中的面积判断算法得到出行者的OD信息。最后利用所提出的方法对重庆市九龙坡区杨家坪地区进行了OD调查,得到OD发生集中专题和OD线专题。     

基于uIP协议栈的机房远程监测系统的实现

针对校园网机房安全的实时监测问题,设计了机房远程监测系统,可实时地观测机房环境状况及服务器运行状况,并通过设置一定的阀值,将报警信息发送到监测者的手机上.本系统在开源TCP/IP协议栈uIP的基础上,开发了Web Server服务模块,将监测到的信息发送到监测者的浏览器上.并可通过GSM通信模块,将报警信息发送到监测者的手机上.     

一种新的硬判决并行干扰消除算法

多址干扰的存在是影响CDMA系统性能和限定系统容量的重要因素。针对多址干扰信号的特点，研究了一种改进的硬判断决并行干扰多用户检测器。分析和仿真结果表明，该多用户检测器具有更好的性能和抗远近效应的能力，具有广泛的应用前景。     

基于移动Agent的MANET多约束QoS路由算法

针对节点能量和可用带宽2个约束条件的问题,提出了一种基于移动Agent的QoS路由算法.该算法利用移动Agent采集网络中各节点的详细信息,以最大链路的生存时间作为选择路由的基础,增强了路径的稳定性;采用多路径策略,以缩短路由重构的时间;优先选择剩余能量多的节点,延长了网络的生存时间.利用网络仿真工具NS2进行的仿真实验结果证明,与AODV协议相比,该算法具有较高的包传输率和较低的端到端平均延时.     

工艺数字化系统中工艺尺寸及其精度的确定

说明了工艺数字化系统（PDS）中工艺尺寸及其精度确定的意义，分析了已有的计算机辅助确定工艺尺寸方法的特点，研究了确定工艺尺寸的数学模型，开发了计算机辅助确定合理工艺尺寸及其精度的系统，并论述了系统的工作模式及特点。     

基于模糊层次分析法的移动桥梁装备安全性评估研究

针对移动桥梁装备安全性评估方面的空白,采用模糊层次分析法（FAHP）,从宏观上对现有移动桥梁的安全性进行评价,根据其特点,把某型移动桥梁分为运输系统、桥体、架设系统三部分,分别建立不同元素间的模糊一致判断矩阵,确定隶属函数、权重值,最后得出定量评判结论,同时结合试验说明评判结论与实际情况相符。此评估方法为桥梁装备平时的储备保养及使用时维修评价提供了理论依据。     

基于Gram-Schmidt正交化法的串行干扰消除算法

基于Gram-Schmidt正交化法,提出了一种改进的串行干扰消除算法.不同于传统的串行干扰消除算法,该算法运用Gram-Schmidt正交化法,通过扩频序列获取正交序列作为最优解扩码,使得检测器每一级最强用户的解扩码与其他用户的扩频码所张的子空间正交,从而实现对多址干扰的完全抑制.给出了具有幅度失配的系统误码率近似公式,讨论了幅度失配对检测性能的影响.仿真结果表明,改进算法能有效抑制CDMA系统中的多址干扰,改善系统性能.     

基于优化方法的自适应跳频地址编码方法

为提高跳扩频通信系统抗干扰性能，提出了在多载 直接序列跳扩频（ＭＣ－ＤＳ／ＦＨＣＤ－ＭＡ）通信系统中实现自适应跳频（ＡＦＨ）方式时，基于优化的自适应跳频地址编码方法。在给定信道仿真参数的前提下，对自适应跳频系统的误码性能进行了分析，结果表明自适应方式优于传统方式。     

NETWORK MANAGEMENT WITH SECURED MOBILE AGENT

IntroductionMobile Agents equipped with intelligence,of-fer new technology that helps automate NetworkManagement activities,which are increasingly be-coming complex due to exponential growth of in-ternet users,and thus demanding higher levels ofhuman manager expertise and involvement.Well-known network management protocols that areused to monitor and manage network devices in-clude Simple Network Management Protocol ( SN-MP) and Common Management Information Proto-col ( CMIP) ,SNMP be…     

A Stable Switch Method Based on Fusion in Uncalibrated Visual Servoing

Stable switch control between multiple cameras for uncalibrated visual servoing was studied. Switch images based on fusion were presented to get the continuous dynamic image Jacobian matrix among robots and distributed visual sensors. The designed fusion algorithm is suitable to have dynamically adjustable fusion weights, and the fusion structure was analyzed. Simulations and experiments without any knowledge of mobile robots and uncalibrated visual sensors show that the method has higher adaptability than the traditional instant switch control method. The method can enhance the system stability at the switching process.     

Recovery from Wormhole Attack in Mobile Ad Hoc Network （MANET）

Introduction Mobileadhocnetwork(MANET)isaself-organizing,multi-hopwirelessnetwork.Commu-nicationsinadhocnetworkdonotrequireexis-tenceofacentralbasestationorafixednetwork infrastructure.Self-organizingandinfrastruc-turelessnessmakeadhocnetworkeasytobeap-pliedtothoseemergencyenvironmentswherethere isnotbasestationsoraccesspoints.However,on theotherhand,theyalsoopenthenetworktovari-oussecurityattacks.Amongthoseattacksthat havebeendiscoveredsofarinMANET,worm-hole[1]isoneofthemostseriousattack…     

GPS/DR组合导航车载单元的开发研究

随着城市车辆的急剧增长和道路交通状况的拥挤,以全球定位系统（GPS）定位技术为主的民用车辆的定位导航和监控技术得到了飞速发展.通过研究GPS和航位推算系统（DR）的组合导航技术,给出了GPS/DR组合导航系统车载单元的设计方案.由GPS接收机、压电陀螺仪、DVD、单片机、手机模块、车载里程仪、工控微机组成的车载单元具有车辆自动导航和监控报警功能.     

CDMA 网络中基于 QoS 保证的呼叫接纳控制策略

基于CDMA（code division multipleaccess）系统接纳控制（call admission control，CAC）机制没有完全考虑各种多媒体业务的现状，研究了CDMA系统中剩余容量的计算方法，采用更加符合目前无线多媒体网络中业务实际情况的业务模型，给出了一种针对多媒体业务的基于QoS（quality of service）保证的动态CAC算法．分析与仿真结果表明，该算法在保证各种业务QoS要求的情况下，可以显著改善CDMA系统的呼叫等待延时和中断率等性能，提高系统资源的利用率．     

3S集成技术在土地利用动态监测中的应用

针对基于RS和G IS的土地利用动态监测方法可靠性差,精度低,提出了RS,G IS和GPS集成技术.在2000年TM遥感影像解译数据的基础上,以2004年中巴资源卫星(CBERS-02)遥感影像数据为信息源,对2004年遥感影像进行了解译,修改了2000年数据库.在野外用手持GPS接收机对解译成果进行了验证,更新了解译的数据库;利用G IS技术的空间分析功能,提取出了2000~2004年间土地利用/覆被变化信息,得到了高精度的土地利用动态变化数据库,并在此基础上对土地利用动态变化信息进行了分析.实验结果表明,利用3S集成技术可以提高土地利用信息的可靠性和精度.