GPRS体系结构及管理功能

GPRS(General Packet Radio Service)通用分组无线业务是在现有GSM网络基础上发展起来的一种标准化的分组交换数据业务，它应用无线分组原理在移动台MS和外部分组数据网络PDN(Packet DataNetwork)之间实现高效的数据通信。本文主要介绍GPRS体系结构及其量大功能、GPRS会话管理以及GPRS移动管理功能。     

CSM高速移动数据业务-CPRS

本文介绍了GSM移动数据业务的进展,对移动数据业务提供方式进行了分析研究,着重介绍了GPRS的系统组成,GPRS网络工作原理,GPRS提供业务类型及特点,并例举了GPRS的应用。     

GSM高速移动数据业务-GPRS

本文介绍了GSM移动数据业务的进展、对移动数据业务提供方式进行了分析研究,着重介绍了GPRS的系统组成,GPRS网络工作原理,GPRS提供业务类型及特点,并例举了GPRS的应用     

GSM高速移动数据业务—GPRS

介绍了GSM移动数据业务的进展,对移动数据业务提供方式进行了分析研究,着重研究了GPRS的系统组成,GPRS网络工作原理,GPRS提供业务类型及特点,并例举了GPRS的应用。     

GSM高速移动数据业务GPRS

本文介绍了GSM移动数据业务的进展,对移动数据业务提供方式进行了分析研究,着重介绍了GPRS的系统组成,GPRS网络工作原理,GPRS提供业务类型及特点,并例举了GPRS的应用。     

GPRS——通用无线分组业务技术及应用

本文对GPRS进行了基本的描述,分析GSM移动数据业务的进展,对移动数据业务提供方式进行了分析研究,介绍了GPRS的系统组成,GPRS提供业务类型及特点,并例举了GPRS的应用。     

上海移动数据网综合网管的实现

随着中国移动通信数据业务的飞速发展．上海移动所提供的数据业务也越来越多。目前上海移动的主要数据业务包括城域、GPRS、短信、WLAN、VoIP、WAP、LBS、EMAIL等业务。这些业务系统的网管主要采用设备提供商提供的网管系统，基本停留在网元管理层次，无法满足“集中监控、集中维护、集中管理”的现代化网络管理模式的需要。为了提高网络的管理、维护能力，为业务实现和实施提供有效的管理维护手段，全面提升数据业务的服务质量，上海移动公司进行了数据网综合网管的建设。     

GPRS中分组路由和移动性管理问题的研究

GPRS(General Packet Radio Service,通用分组无线业务)在GSM网的基础上提供分组方式的数据业务,从而实现无线资源的共享.在GPRS的实现中需要解决三个重要的问题,即分组数据的路由、移动性管理、分组无线协议和无线资源管理问题.本文着重研究前两个问题.通过分析对比移动IP和GSM网的路由(接续)和移动性管理方案,阐明GPRS的分组路由和移动性管理的具体解决方案.     

基于GPRS技术实现移动互联网

随着网络的迅猛发展,第2．5代网络产品GPRS（通用分组无线电业务）顺应时代潮流,成为第2代移动通信向第3代移动通信过渡中最引人瞩目的一种技术。GPRS是在现有的GSM（全球移动通信系统）基础上发展起来的一种移动分组数据业务,采用分组交换技术,相对GSM技术,GPRS技术更加经济,数据业务也更加丰富。文中基于GPRS技术对实现移动互联网应用进行探讨。     

GPRS技术

作为一种重要的移动数据业务， GPRS能够确保分组模式数据应用的成本效益和网络资源的有效利用，可以使网络运营商以一种动态和灵活的方式最大可能地利用他们的网络资源。本期将讲述 GPRS技术的最后一讲： GPRS的移动性管理与路由管理。前两期已述： GPRS的网络结构、功能与业务， GPRS的空口接口与无线资源管理。     

请求计时到引起手机WAP接入失败的协议分析

针对请求计时到引起GPRS网络中手机WAP接入失败的情况,从WAP协议栈中的WSP协议层、WTP协议层、GPRSRLC/MAC协议层以及GSMUm接口第三层对同时在GPRSGb接口和GSMUm接口采集到的消息进行了关联的协议分析。分析结果表明,请求计时到引起GPRS网络中手机WAP接入失败是由于在超时重传消息过程中手机侧的WTP协议层无响应所致,与GPRS无线承载网络及GSMUm接口无关。     

基于无线GPRS/SMS方式的移动基站动力环境监控系统

基于无线GPRS/SMS方式的移动基站动环监控系统,利用GSM短信和GPRS无线数据作为传输平台,实现对移动基站机房的动力环境信息的远程遥测、遥控、遥调和遥信,是基站动环监控的有效解决方案,特别是对边际基站、室内覆盖基站的监控,克服了有线方式下投资大、建设周期长的不足,实现了投资效益最大化。     

多串口转GPRS组网方式的基站监控应用

在无有线传输资源的移动基站中,基站内智能设备通过多串口转GPRS传输方式实现了对基站的远程监控,提高了监控覆盖率。GPRS技术使用方便,成本较低,可以稳定地传送数据,有利于大规模网络的建立。     

Optimizing Web delivery over wireless links: design, implementation, and experiences

World over wide-area wireless Global System for Mobile Communication (GSM) networks have been upgraded to support the general packet radio service (GPRS). GPRS brings "always-on" wireless data connectivity at bandwidths comparable to that of conventional fixed-line telephone modems. Unfortunately many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the Web over GPRS. In This work, we show what causes the web and its underlying transport protocol TCP to underperform in a GPRS wide-area wireless environment. We examine why certain GPRS network characteristics interact badly with TCP to yield problems such as: link underutilization for short-lived flows, excess queueing for long-lived flows, ACK compression, poor loss recovery, and gross unfairness between competing flows. We also show that many Web browsers tend to be overly aggressive, and by opening too many simultaneous TCP connections can aggravate matters. We present the design and implementation of a web optimizing proxy system called GPRSWeb that mitigates many of the GPRS link-related performance problems with a simple software update to a mobile device. The update is a link-aware middleware (a local "client proxy") that sits in the mobile device, and communicates with a "server proxy" located at the other end of the wireless link, close to the wired-wireless border. The dual-proxy architecture collectively implements a number of key enhancements-an aggressive caching scheme that employs content-based hash keying to improve hit rates for dynamic content, a preemptive push of Web page support resources to mobile clients, resource adaptation to suit client capabilities, delta encoded data transfer of modified pages, DNS lookup migration, and a UDP-based reliable transport protocol that is specifically optimized for use over GPRS. We show that these enhancements results in significant improvement in web performance over GPRS links.     

基于ZigBee的城市公交车定位系统设计

利用无线传感器单片机CC2431和CC2430设计了一个基于ZigBee的公交车无线定位系统。传统的定位都是采用GPS或者GPRS的定位。GPS定位系统设计简单,可以使用免费的定位卫星资源,但是移动台到控制中心的数据传送需要借助其它网络资源;GPRS定位是基于移动蜂窝式通信的定位,使用现有的移动网络,但是带宽低,不利于突发事件的快速处理。本文设计的Zigbee的无线定位系统基于无线单片机CC2431[1],利用CC2431自带的RSSI定位引擎[2],再运用无线自组网[3]进行定位并向控制中心传送定位信息。该系统设计简单,定位精确度高,设备成本低廉,适合现代化城市的公交车系统智能管理。     

On demand network-wide VPN deployment in GPRS

Mobile Internet requires enhanced security services available to all mobile subscribers in a dynamic fashion. A network-wide virtual private network deployment scenario over the General Packet Radio Service is proposed and analyzed from a security viewpoint. The proposed security scheme improves the level of protection that is currently supported in GPRS and facilitates the realization of mobile Internet. It secures data transmission over the entire network route from a mobile user to a remote server by utilizing the default GPRS ciphering over the radio interface, and by deploying an IP VPN over the GPRS core, as well as on the public Internet. Thus, on-demand VPN services are made available for all GPRS network subscribers and roaming users. The VPN functionality, which is based on the IPsec framework, is outsourced to the network infrastructure to eliminate the potential computational overhead on the mobile device. The VPN initialization and key agreement procedures are based on an Internet Key Exchange protocol proxy scheme, which enables the mobile station to initiate VPN establishment, while shifting the complex key negotiation to the network infrastructure. The deployed VPN operates transparently to the mobile subscribers' movement. The required enhancements for security service provision can be integrated in the existing network infrastructure; therefore, the propose security scheme can be employed as an add-on feature to the GPRS standard.     

The Complementary Use of 3G WCDMA and GSM/GPRS Cellular Radio Networks

The traffic performance of integrated 3G wide-band code division multiple access (WCDMA) and GSM/GPRS network is evaluated. This type of network links two cellular radio systems which have different set of frequency bands and the same coverage size. The base station of 3G WCDMA is installed on an existing GSM/GPRS site. Dual-mode mobile terminals use handoff to establish calls on the better system. The soft handoff or inter-frequency hard handoff occurs when mobile terminals of 3G WCDMA or GSM/GPRS move between two adjacent cells, respectively. The inter-system hard handoffs are used between 3G WCDMA and GSM/GPRS systems. The data rate conversions between different systems, soft handoff region size, multiple data rate multimedia services, and the effect of the mobile terminal mobility on the user mean dwell time in each system are considered in the study. The simulation results demonstrate that a great traffic performance improvement on the complementary use of 3G WCDMA and GSM/GPRS cellular radio networks compared with the use of GSM/GPRS cellular radio networks. When high-data rate transmission is chosen for low-mobility subscribers, both the handoff failure probability, and carried traffic rates increase with the new call generation rate. However, both rates decrease conversely with the increasing new call generation rate as soon as the new call generation rate exceeds a critical value. This causes the integrated networks saturation. The higher mean speed for the mobile terminals produces lower new call blocking probabilities and total carried traffic. The new call blocking probabilities and total carried traffic increase with the size of the soft handoff region.     

GPRS数据业务性能分析

基于D-BMAP/D/1排队模型分析GPRS数据业务在简化的一步接入模式以及不同服务速率下的性能,包括RLC/MAC缓冲区队列的平均长度、小分组(Mini-Packet)的平均时延和丢弃率等.分析结果表明:当定时器T₃₁₈₂时间变长时,时延缩短,丢弃率降低;处于空闲状态的移动台产生新会话的概率越大,时延越长;缓冲区容量增加,丢弃率明显降低.但是随着每个会话中分组呼叫数目的变化,时延变化不显著.     

IP Paging Service for Mobile Hosts

In wireless networks, mobile hosts must update the network with their current location in order to get packets delivered. Paging facilitates efficient power management at the mobile host by allowing the host to update the network less frequently at the cost of providing the network with only approximate location information. The network determines the exact location of a mobile host through paging before delivering packets destined to the mobile host. In this paper, we propose the concept of paging as an IP service. IP paging enables a common infrastructure and protocol to support the different wireless interfaces such as CDMA, GPRS, wireless LAN, avoiding the duplication of several application layer paging implementations and the inter-operability issues that exist today. We present the design, implementation, and detailed qualitative and quantitative evaluation, using measurements and simulation, of three IP-based paging protocols for mobile hosts.     

基于短信和GPRS／CDMA-1X的基站动力环境远程监控系统

基于短信和GPRS／CDMA-1X的基站动力环境远程监控系统,充分利用了公共移动网络,克服了传统方式数据非实时性、通信性能差、组网不灵活、设备成本高等缺点。系统采用分层结构设计,借助短信和GPRS／CDMA-1X无线数据网络作为传输平台,并结合GIS技术,实现了对基站工作环境的实时、连续、无人值守监控,提高了基站维护的效率。