Performance Evaluation of Distributed Database Architectures for UMTS Service Deployed in an Urban Area

The design of distributed databases (DDBs) destined to store user information is a key issue in third-generation mobile communication systems such as UMTS. In particular, the problem of determining the most appropriate DDB architectures for UMTS is critical due to the anticipated requirements of high distribution and adaptability of information. This paper presents a model which allows different DDB architectures to be evaluated, in terms of query loads and average search times. The model proposed puts no constraints on either the DDB structure arrangement or the user position characterization. The paper also discusses a real, significant case study, concerning a query operation arising from an access procedure performed on the DDB of a communication network covering an urban area.     

微软嵌入式操作系统的分析和比对(上)

文章介绍了微软的嵌入式操作系统产品线,分析了WinCE 6.0和.NET Micro framework技术特点.根据嵌入式系统的要求,还比较了微软和嵌入式Linux、VxWorkss的差异和各自特色.     

移动互联网时代的终端产业发展趋势

随着全球进入移动互联网时代,移动终端产业正面临深刻变革。介绍了国际智能终端产业的现状,分析了我国终端产业面临的机遇、挑战,以及面向移动互联网的终端产业的发展趋势。     

普及型手机LCD背光趋向使用LDO

文章从技术和市场经济的角度对手机LCD背光LED驱动器的技术演变进行分析,论述了LDO的性价比为普及型手机LCD背光应用赢得新的机遇。     

Location-Independent Access in Mobile Systems

In this paper, we report on the design of a protocol for transparent, location-independent access in mobile systems. The protocol, termed by us Mobile Client/Server Protocol (MCSP) is an implementation of a communication layer on a mobile host and a stationary machine within the wireline network, and provides middleware functionality. The MCSP supports communication services through the client/server paradigm to transaction-oriented applications distributed between the mobile and a set of service and information brokers. To support the mobile and the wireless environment, a surrogate process is created within the fixed network to perform operations on behalf of the mobile within the fixed network. The MCSP then loosely couples the communicating entities, thus reducing the overhead associated with handoffs and disconnects, so characteristic of the mobile environment. Of particular interest is the application of the MCSP to location-based services, for example, the Intelligent Vehicle Highway Systems [1].     

WAP的现状和存在的问题

本文介绍了无线应用协议（ＷＡＰ）的基本原理、产生背景、协议功能和应用环境,重点论述了ＷＡＰ在中国的发展现状以及制约其发展的几个问题。     

空中下载技术及其在移动互联网中的应用

随着移动互联网的发展,空中下载技术必将得到越来越广泛的应用。文章介绍空中下载系统的结构,讨论两种空中下载过程的实现方式,最后分析空中下载技术在中国的应用现状及其在无线互联网中的应用前景。     

Effects of fade distribution on a mobile satellite down-link and up-link performance in a frequency reuse cellular configuration

In a mobile satellite system with a frequency reuse cellular configuration, significant co-channel interference can be experienced due to the antenna side-lobe level. The signal will be subjected not only to its own fading, but also to the effect of the varying degree of fading on the co-channel interferer, and this interference will behave differently in the up and in the down-link. This paper presents a quantitative evaluation of the combined effects of fades and co-channel interference on a mobile satellite link.     

流量经营中内容资源管理技术研究

通过分析移动互联网业务增长给电信运营商经营模式带来的变化,指出了流量经营中的内容资源管理趋势;通过分析研究业内部署的各种内容资源管理系统及其成效,提出了内容资源模块化管理思路及内容资源管理架构,阐述了业务场景,进行了现网验证,并取得了预期效果。     

The design and evaluation of an end-to-end handoff management protocol

We introduce an efficient protocol for end-to-end handoff management in heterogeneous wireless IP-based networks. The protocol is based on the stream control transmission protocol (SCTP), and employs a soft-handoff mechanism that uses end-to-end semantics for signaling handoffs and for transmitting control messages. The design goal of this protocol is twofold—first, to reduce the home registration delay, and, second, to eliminate the tunnelling cost which exists in current proposals, such as Mobile IP and its derivatives. Furthermore, we propose successive enhancements to the initial mobility management framework for achieving better scalability. We present strong analytical and simulation-based results that show performance improvements over existing approaches. Antonios Argyriou is a Ph.D. candidate in the school of electrical and computer engineering, Georgia Institute of Technology. He received his M.S. degree from the Georgia Institute of Technology in 2003, and the diploma from Democritus University of Thrace in 2001, both in electrical and computer engineering. His research interests spawn in all aspects of computer networking while specific interests include wireless networks and multimedia communications. He is a student member of IEEE and ACM. Vijay Madisetti is a professor of electrical and computer engineering at the Georgia Institute of Technology. He splits his time among teaching, research and entrepreneurship. His interests are design, prototyping, and packaging of electronic systems, virtual prototyping, embedded software systems, and computer networks. He obtained his Ph.D. in electrical engineering and computer science from the University of California at Berkeley. He is a member of the IEEE and the Computer Society.