GPRS虚拟专用网络技术的研究与分析

介绍了一种基于GPRS网络的端到端VPN解决方案,着重对其中的关键协议的使用情况、兼容性以及该方案的优缺点等进行了分析和研究,从而对今后GPRS虚拟专网的实际规划设计提供了参考。     

浅谈GPRS VPN技术在邮政系统中的应用

通用分组无线业务GPRS-General Packet Radio Service,是GSM移动电话用户使用的一种数据业务,是GSM一般业务的延伸和扩展.凭借实时在线、按量计费、快捷登录、高速传输、自如切换等优点,实现点对点、点对中心的对等数据传输.GPRS在邮政数据传输中已经大量应用.从GPRS和VPN的构成入手,重...     

General Packet Radio Service (GPRS): architecture,interfaces, and deployment

This article provides an overview of General Packet Radio Service (GPRS). GPRS reuses the existing GSM infrastructure to provide end‐to‐end packet‐switched services. Benefits of GPRS include efficient radio usage, fast set‐up/access time and high bandwidth with multiple timeslots. GPRS also provides a smooth path for GSM evolution to the third generation mobile network. Specifically, a third generation network can continue to utilize the GPRS IP backbone network. We describe the GPRS network nodes and the interfaces among these nodes. Deployment issues for GPRS are also elaborated. Copyright © 2001 John Wiley & Sons, Ltd.     

On the deployment of picocellular wireless infrastructure

Wireless LANs are becoming increasingly common in both home and office networks. Additionally, wireless Internet service providers have begun installing public WLANs in airports, hotels, and other frequently trafficked areas. This article analyzes deployment strategies for such networks, specifically for possible future systems utilizing bands of up to 60 GHz. A major part of the installation cost stems from network planning, wiring, and manpower for setting up base stations. It is therefore crucial to find ways to simplify the network installation and reduce the deployment costs, while at the same time maintaining the desired system performance. We show that even simple installation rules can often achieve adequate coverage results. However, proper network planning is in some situations necessary to achieve adequate coverage. Therefore, we examine different combinatorial optimization methods for obtaining close to optimal positioning of WLAN access points and compare the performance of the proposed algorithms to the simple installation methods. The optimization algorithms used in this article evaluate an objective function that aims to maximize both the coverage area and the overall signal quality over a discrete search space. Random search algorithms can yield very good solutions, but often exhibit difficult convergence properties. Successive removal algorithms, such as pruning, converge in polynomial time, but usually produce suboptimal solutions. We therefore propose a combination of the two approaches, using pruning to obtain an initial set of the base station positions and refining these by using neighborhood search or simulated annealing.     

基于GPRS业务的GPS手持式信息传输系统

本文介绍了结合GPRS业务的GPS定位信息传输系统。主要介绍了基于iTrax02的GPS模块和基于CMS91的GPRS模块的硬件结构，相应的数据格式和开发方法。     

On the deployment of RED on shared-memory buffers

We have proposed novel buffer management algorithms for the deployment of random early detection (RED) on class-based queues with shared-memory buffers, where the total buffer is shared under complete sharing, sharing with minimum allocation, and complete partitioning policies. This letter provides an analytical evaluation of these schemes by deriving the drop probability equations using the traditional M/M/1/K queueing model. This letter also provides a comparison of the delay and loss ratio of these scheme under TCP flows. Sharing with minimum allocation is shown to give the best performance     

On the establishment of an access VPN in broadband access networks

Many corporate networks use the Internet as a cost-effective substitute for expensive leased lines and long-distance telephone calls, for allowing their users to have on-demand connectivity into their intranets through ad hoc tunnels, a concept known as access VPN. Establishing an access VPN in a broadband access network is very often a difficult networking challenge that requires several tunnels to be established between the various involved entities. This is especially the case in an open broadband access network where the association between a host and its ISP is not known to the network in advance. This article discusses several schemes for establishing an access VPN in a broadband access network, and explains the need for the various tunnels in each scheme.     

VPN用户认证技术

虚拟专用网络绕开防火墙的安全保障机制提供对内网资源的访问,因此高强度的用户认证功能是必须的。目前常用的认证技术包括无中心式的基于签名技术的认证机制以及基于数字证书的中心式认证机制。文章对这两类认证技术在ＶＰＮ中的应用进行了细致的研究和分析,为ＶＰＮ用户认证技术的实现提供了技术框架。     

GPRS网络的关键传输技术——隧道技术

简述了GPRS中数据传输的情况，介绍了GPRS隧道的特点和涉及的3个重要规程，最后给出了用户数据通过隧道传输的各种情况。     

GPRS技术讲座 第6讲 GPRS会话管理

会话管理是指在移动台和外部数据网络之间建立分组数据传输的信令处理过程。本文介绍了CPRS系统中PDP地址、PDP移动场景的概念,并以PDP移动场景激活过程为例简单描述了GPRS的会话管理过程。     

On the optimal random deployment of wireless sensor networks in non-homogeneous scenarios

Random scattering of WSNs is needed in many practical cases due to the large scale of the network required or to the inaccessibility of the terrain. However several important features of deployments of this type have been neglected due to their analytical complexity. Node placement must guarantee correct operation: if nodes are too separated many would be isolated and data would not reach the sinks. Besides, if the nodes are too close, the area covered would be small and little information would be retrieved. Moreover, the target area cannot be considered homogeneous since in real-life situations some zones are more important than others. This paper addresses these constraints by proposing and solving an optimization problem which maximizes network sensing coverage. In our model several clusters of nodes are spread over the target area following Gaussian random distributions, and the goal is to decide the optimal launch point and the dispersion for each cluster. This corresponds to real situations where clusters are dropped in an airborne launch in which dispersion is controlled by the release altitude. The problem is solved by considering iterative steps where single cluster deployments are addressed. Several tests validate our approach and indicate that our method outperforms previous approaches, especially in deployments with a low number of nodes, which are more challenging from the optimization perspective.     

On femto deployment architectures and macrocell offloading benefits in joint macro-femto deployments

This article provides an overview of opportunities and challenges related to joint deployments of macro and femtocells. It provides insights on possible deployment architectures for femtocells along with an analysis framework for quantifying macro offloading benefits in realistic network deployment scenarios by means of advanced performance analysis techniques. Such benefits include potential enhancement in quality of radio signals for users served by the macro network in joint macro-femto deployments. This in turn translates into potentially better data rates (throughput) for macrocell users and may offer the possibility of adding more users to the macro network while preserving the network configuration -- resulting in direct capital expenditure savings. The approach taken in this article consists of creating a framework for quantifying macro offloading benefits in joint macro-femto deployments. A baseline configuration where all users (indoor and outdoor) are served by a traditional macro network (state-of-the-art macro only network) is considered first. The analysis is followed through joint macro-femto deployments, where femtocells serve indoor users. Through comparison of the baseline configuration and the joint macro-femto analysis, we quantify the benefits of the joint macro-femto deployment.     

On the scalability of fixed broadband wireless access network deployment

Fixed broadband wireless access systems, such as the local multipoint distribution service, use an open system architecture that supports a scalable solution for the Internet services over IEEE 802.16 wireless networks. This article presents an overview of various features of BWA systems toward realizing a high level of scalability to support a potentially fast expanding network. This is achieved by optimizing various network resources, which include utilizing the available bandwidth efficiency, making a minor enhancement to an existing system that minimizes the disruption to network services during the network expansion process, and combining the benefits of different features to increase network capacity.     

GPRS支持下的WPKI设计与实现

针对GPRS系统接入安全风险大的特点,提出了与WPKI相结合的终端接入认证方案,并对该方案进行了分析研究。提出了将无线公钥基础设施（WPKI）应用于GPRS平台以获得应用层无线安全保障的方案。设计了一个将WPKI体系和GPRS平台结合起来的实验系统,给出了各个功能模块的逻辑和功能结构图,并基于开源代码库Openssl对试验系统中的CA服务器和RA服务器进行了实现和测试,在GPRS平台上实现了WPKI核心内容一证书申请、证书签发、证书查询、证书撤销等。经过测试,该实验系统能在实际的GPRS平台上可靠运行。     

GPRS网络中的GSN

本文介绍GPRS的组网和GSN节点的设置，对SGSN与GGSN的分设与合设的优缺点作了介绍。     

GPRS中的移动性管理

本文首先概要介绍了ＧＳＭ 中的一种先进分组数据技术ＧＰＲＳ的结构， 然后重点介绍其移动性管理功能， 并对激活和位置管理过程进行了详细分析。     

基于GPRS网络的智能家居控制系统

提出了一种新型的远程家居控制系统,系统能够实现通过手机客户端操作控制家庭电器开关等功能.系统由布设在家庭的主控制元件C8051F040单片机、分控元件42BYG250-33两相步进电机及T73_SRD_5V继电器模块、BENQ_M23_GPRS模块以及安装在手机的客户端软件组成.通过GPRS无线网络远程操控如电灯、热水壶等家庭电器的开关功能及窗帘的拉合,实现家居智能化.     

兵力需求的运作机理研究

兵力需求的影响因素有很多,研究这些因素之间的关系及对兵力需求的影响是一个新的课题.提出了兵力需求运作机理的研究框架,在此基础上,依照辨析关键因素、分析因果关系、评价相互影响、分析计算结果的研究步骤,采用因果关系图、层次分析法(AHP)、网络分析法(ANP)等方法,结合实例对具体问题进行了详细分析.通过研究,得出了影响兵力需求的关键因素之间的量化关系,结论具有一定的科学性.     

MPLS VPN的SLA性能研究

主要介绍了SLA技术以及SLA在MPLS VPN中的实现，并且以实验方法测试了由Cisco设备构建的MPLS网络中所提供的VPN的QoS保证。     

GPRS的漫游——实现移动分组接入的解决方案

首先简单介绍了GPRS的系统结构，在此基础上给出了GPRS网络中的APN（access point name）和域名系统的概念，分析了漫洲情况下GPRS是如何支持分组数据路由的过程，最后介绍了GPRS系统中的IP地址管理的问题。