基于3G的M-Government模型及数据同步问题研究

电子政务代表了政务实施发展的趋势和方向,移动电子政务是电子政务的延伸和发展.3G网络作为新一代移动通信系统,推动了移动电子政务的发展,3G网络的各种优势带动了移动政务各种应用的推广.本文提出了基于3G网络的移动电子政务模型,并与基于2G的模型进行了比较.此外,本文还研究了移动电子政务中必须考虑到的数据同步问题,并提出了一个切实可行的模型.     

交通电子政务3G移动办公安全技术研究

文中主要对交通电子政务3G移动办公的安全技术进行研究。从移动办公平台自身的特点出发,分析该平台可能遭受到的安全威胁,进行移动办公平台安全体系结构设计,并针对主要安全威胁,提出了交通电子政务3G网络办公安全解决方案,以最大限度地提高该平台的稳定性和安全性。     

移动核心网转型以适应未来3G、IMS格局的几点分析

随着3G的日益临近，如何改造目前的2G移动核心网，使其既能支持现有的2G网络，又能适应未来3G网络的发展，已成为当今移动核心网络规划、建设必须考虑的问题之一。为了突破现有移动核心网设备的性能瓶颈，支持移动核心网向下一代移动网络（面向IMS）的演进，业界提出了基于IP的、兼容2G／3G、面向IMS的移动软交换核心网建设思路：即建设以软交换技术为核心，将业务承载与信令控制分开，基于IP承载的面向3G、IMS的软交换核心网。这种核心网既支持现有2G网络，又支持未来的3G网络，还支持TDM／IP混合组网。本文以陕西移动为例就移动核心网如何转型以适应未来3G、IMS格局，作几点分析。     

信息敏感行业3G移动办公安全解决方案

随着运营商对3G投资的不断增加,3G行业快速发展,基于3G网络的移动办公得到了广泛的应用,然而,随之而来的安全问题也日益突出。本文分析了3G移动办公面临的安全问题,构建了5大安全体系,从专用APN、身份认证、网络隔离等方面提出了基于3G移动办公的安全解决方案。     

移动IP及基于IPv6的切换

本文首先对移动IP的工作原理作了简单的介绍，进而提出作为未来移动网络首选的移动IPv6协议的特点。在此基础上，对基于IPv6的各种切换方案作了深入的探讨，引入了类比于3G移动通信切换的思路，提出了基于IPv6切换的下一步研究方向。     

3G中增强的3层动态位置管理建模与分析

基于3G网络中由HLR(home location register)、GLR(gateway location register)、VLR(visitor location register)构成的3层数据库结构,提出了基于移动的增强动态位置管理策略,重点分析了该策略下位置更新和寻呼的代价模型。并使用该代价模型对3G网络中基于移动的增强动态位置管理策略、基于移动的基本动态位置管理策略和静态位置管理策略进行了评价,计算结果显示增强动态位置管理策略要优于基于移动的基本位置管理策略和静态位置管理策略。     

可管可控的移动VPDN方案研究

移动VPDN也称为无线IP专网或3G IP专网,为广大企业客户提供了基于3G宽带网络的数据专网服务.本文对移动VPDN的组网构建、安全认证及业务保障等方面进行了分析研究,并提出了移动VPDN在行业信息化建设中可管可控的新组网模型.     

面向移动电子政务的CA中心建设模式研究

根据移动电子政务的发展特点,结合移动政务CA中心的建设,分析层次CA与桥CA结构两种PKI信任模式的优缺点,提出现阶段移动政务的CA中心建设先采用层次CA结构模式,依托现有的电子政务CA中心,构建区域型（省级）C A中心的建设模式,并逐步向桥CA混合型结构发展,进一步保障移动政务应用的安全性。     

基于B/S结构的移动电子政务系统的设计

针对当前无线通信和移动计算技术在政务工作中的应用模式的特点,本文采用Browser/Server三层结构设计模式,利用ASP技术和SQL Server作为后台数据库服务器设计了此移动电子政务系统,分析了政务办公的模块结构,讨论了政务系统的设计与开发,并提出了办公系统的总体结构。系统的成功开发实现了移动电子政务系统的动态管理,使得系统更加高效、方便,提高了工作效率,快捷、便利的为公众和办公人员提供了政务服务。     

基于语义互操作的政务知识协同模型研究

基于语义互操作的电子政务协同系统是电子政务的发展趋势。分析了构建基于语义互操作的政务知识协同系统的主要任务和方法,提出了一个基于语义互操作的政务知识协同系统框架模型,详细阐明了其设计思路及各部分功能,重点给出电子政务信息单元自治模型和政务信息本体互操作模型的组成结构和工作机制。     

The 3G-324M protocol for conversational video telephony

As mobile operators worldwide migrate to third-generation (3G) networks, conversational video-telephony services are becoming a key differentiator between new 3G offerings and existing 2G/2.5G services. Although it's possible to have limited video-based services - such as a multimedia messaging service - that deliver pictures and video clips over 2.5G services, these are delay-insensitive applications that could run over a packet-based wireless network like general packet radio service (GPRS) or code division multiple access (CDMA)'s 1XRTT. For delay-sensitive applications such as conversational video telephony, present 3G packet bearers are inadequate, and the Third Generation Partnership Project (3GPP; http://www.3gpp.org) mandates using the 3G bandwidth-guaranteed circuit-switched bearer and the 3G-324M system. The 3G-324M system is a derivative of the International Telecommunication Union (ITU) H.324 protocol standard for low-bitrate multimedia communication, which ITU-T developed for the public switched telephone network (PSTN). This article describes the 3G-324M system, which has been adopted by both 3GPP and 3GPP2 (htpp://www.3gpp2.org), as well as its H.324 roots.     

MPEG-4编解码算法及其视频性能分析

3G移动终端要求能够提供包含语音、数据和图像的多媒体业务，为此3GPP制定了第一个适合3G系统的基于电路交换的多媒体终端模型——3G-324M规范，该模型支持MPEG-4视频处理，它具有高压缩比和容错编码特性。在研究MPEG-4编解码算法基础上进行了MPEG-4视频编码的性能测试。     

基于3G-324M和SIP的3G可视电话互通研究

可视电话业务对网络带宽、时延抖动和丢包率都有较高的要求。中国目前的第三代移动通信技术（3G）网络制式使用不同的无线技术,这使得3G网络中可视电话业务在实现的技术方式上也不同。此处主要研究3G网络中基于3G-324M和SIP协议为基础的电路域和分组域可视电话的实现技术,包括控制协议和呼叫流程。同时针对各自不同的实现方式探讨互通的具体形式,在深入分析可视电话互通理论的基础上设计了互通网关的结构,这对于实现不同制式下的可视电话业务互通具有重要的参考价值。     

3G电路域视频质量问题分析及初步解决思路

从3G电路域业务实现所采用的3G-324M协议入手,对3G电路域业务经常出现的视频质量问题进行了详细分析,并提出了初步解决思路。     

A novel IP to 3G multimedia gateway and its applications

In this paper, we use simple 3G modem cards to design and deploy a novel gateway bridging IP network and Wideband Code Division Multiple Access (WCDMA) 3G mobile network in Hong Kong. A simplified Session Initial Protocol (SIP) is devised to implement the gateway together with the 3G-324M protocol. Compared with the existent similar gateways, our gateway is much more implementable and less cost. Using the proposed gateway, we devise and develop a Video Instant Message System (VIMS) which achieves direct audio and video communications from terminals of the Internet like desktop to 3G mobile phones. Moreover, we produce and accomplish a Mobile Robotic Car Remote Control System (MRCRCS) based on the gateway and VIMS. In the MRCRCS, individuals can distantly control the moving direction of a robotic car by using a VIMS client or a 3G cell phone. By a series of practical experiments, we testify the efficiency and robustness of the gateway and its application scheme.     

MCIP: A 3G/IP Interworking System Supporting Inter-Cluster Soft Handoff

In this paper, a novel 3-tier Mobile Cellular IP (MCIP) access network is proposed for interworking between a third generation (3G) wireless cellular system and a wireline Internet Protocol (IP) based network. An inter-cluster hard handoff scheme and an inter-cluster soft handoff scheme are proposed, based on the 3-tier MCIP system model, the core network protocol stacks, and the underlying MCIP routing algorithm. The core network protocol stack is presented to integrate the 3G radio interface and the IP-based core network, and to provide the access network with capability to support soft handoff macroscopic space diversity. The MCIP hard and soft handoff schemes are compared with the hard handoff schemes used in the Cellular IP and HAWAII access networks. The MCIP access network is more efficient in terms of signaling cost, but has the same scalability as Cellular IP and HAWAII. Both MCIP hard and soft handoff schemes enable IP packets to be delivered within the MCIP access network in-order without loss and duplication, a highly desired attribute for real-time multimedia applications. The advantages of supporting soft handoffs and quality-of-service (QoS) provisioning for real-time services are achieved at slightly increased system complexity.This work was supported by a research grant from the Natural Science and Engineering Research Council (NSERC) of Canada. The authors wish to thank the anonymous reviewers for their helpful comments and suggestions which improve the presentation of this paper. Xin Liu received his B.E. and M.E. degrees in radio engineering from Harbin Institute of Technology (China), in 1990 and 1993, respectively, and his M.A.Sc degree in electrical engineering from the University of Waterloo in 2002. He joined Research In Motion in 2002 as a firmware developer. His current work involves GSM/GPRS and WCDMA firmware development. Weihua Zhuang received the B.Sc. and M.Sc. degrees from Dalian Maritime University (China) and the Ph.D. degree from the University of New Brunswick (Canada), all in electrical engineering. Since October 1993, she has been with the Department of Electrical and Computer Engineering, University of Waterloo, Canada, where she is a full professor. She is a co-author of the textbook Wireless Communications and Networking (Prentice Hall, 2003). Her current research interests include multimedia wireless communications, wireless networks, and radio positioning. Dr. Zhuang received the Premier's Research Excellence Award (PREA) in 2001 from the Ontario Government for demonstrated excellence of scientific and academic contributions. She is an Editor of IEEE Transactions on Wireless Communications, an Associate Editor of IEEE Transactions on Vehicular Technology, and an Editor of EURASIP Journal on Wireless Communications and Networking.     

BOOK REVIEWS

Book reviewed in this articles:
T heory and R esearch in the C ommunicative A rts . By Ernest G. Bormann of the University of Minnesota.
M anagement C ommunication on C ontroversial I ssues . By C. J. Dover.
A ttitude and A ttitude C hange : T he S ocial J udgment -I nvolvement A pproach . By Carolyn W. Sherif, Muzafer Sherif, and Roger E. Nebergall.
T he O pinionmakers . By William L. Rivers.
C lassical R hetoric for the M odern S tudent . By Edward P. J. Corbett.
L inguistics and E nglish G rammar . By H. A. Gleason, Jr.
Books In Breif
A merican and R ussians : R eadings with E xercises in C omposition . By Doris R. Sharpe
T he T heory of M orals . By M. Timur
T he W riting R equirements for G raduate D egrees . By Paul E. Koefod of the University of Florida.
R hetroric : A T ext -R eader on L anguage and I ts U ses By Jim W. Corder of Texas Christian University.
H ow to I mprove Y our S peaking V oice . By Georgiana Peacher     

3G及E3G与WiMAX关系及发展探究

移动技术在近十几年中得到了快速发展,各种创新层出不穷.近年来,3G业务用户发展迅速.WiMAX的出现为移动用户提供了宽带数据业务,威胁了3G数据业务的发展,3G组织决定发展E3G计划.介绍了移动技术的演进历程,3G近期的发展概况,以及E3G计划和进展,并对3G、E3G与WiMAX进行了分析比较.     

3G移动可视电话系统设计

介绍了3G移动可视电话的设计架构模式,基于Window CE操作系统,结合VTApp、3G-324M协议栈、音视频设备驱动、RIL和双端口RAM等相关模块,实现了可视电话这一复杂的多媒体应用系统的运行,描述了相关模块的工作原理与设计思路,并通过对呼出流程图加以介绍的方式,对可视电话系统的运行流程加以阐述。     

Book Reviews

Book reviewed in this article:
T elevision N ews : W riting , E diting , F ilming , B roadcasting . By I. E. Fang
I nnovation in E ducation : N ew D irections for the A merican S chool .
C lassics in C omposition . Edited by Donald E. Hayden
T he experts . By Seymour Freidin and George Bailey.
S ociological methodology 1969. Edited by Edgar F. Borgatta
B usiness communication . By Frank J. Devlin
B roadcast M anagement : R adio and T elevision . By Ward L. Quaal
T he P rofessional J ournalist : a G uide to the P ractices and P rinciples of the N ews M edia . 2nd Ed. By John Hohenberg
E lementary statistics : D ata A nalysis for the B ehavioral S ciences . By Paul A. Games
C umputational H andbook of S tatistics . By James L. Bruning
T eaching R eading to I ndividuals W ith L earning D ifficulties . By Patrick Ashlock and Wineva M. Grzynkowicz
T eacher P reparation in C omposition . By Eugene H. Smith
P ocket O xford D ictionary of C urrent E nglish . Fifth Ed. Compiled by F. G. Fowler and H. W. Fowler. Revised by E. McIntosh.