IMS域的切换研究

基于IMS(IP Multimedia Subsystem)域的通信中由于切换层次的增多导致切换时间的增加,从而使得服务的中断时间加长,这影响了移动中应用的服务质量。在UMTS(Universal Mobile Telecommunication System)R6规范中的切换流程中,跨网络切换采用SGSN(Serving GPRS Support Node)之间的切换而GGSN(Gateway GPRS Support Node)不变,这会导致数据流在IP(Internet Protocol)网络中的迂回,并且多条信令跨网络传输影响了切换的速度,增加了网络流量和端到端延时。该文在现有切换流程上提出了跨GGSN的切换流程,缩短了媒体流在切换过程中的中断时间,并减少了漫游状态下的端到端媒体流引起的网络流量和端到端的数据延迟。     

安捷伦双重传输模式（DTM）测试解决方案

1双重传输模式(DTM)基本原理DTM(Dual Transfer Mode,双重传输模式)是GSM/GPRS/EDGE向UMTS演进的一个关键技术,众所周知,GPRS终端可以分为三类：(1)ClassA,能同时连接到GSM和GPRS系统,能在两个系统中同时激活,并同时收听两个系统的信息,同时提供GPRS分组业务和GSM电路交换业务。     

UMTS网络中SRNS重定位机制的研究

对UMTS网络中的SRNS重定位机制进行了分析和研究,针对在硬切换过程中传统SRNS重定位所需时间过长的缺陷,提出了一种新的SRNS重定位机制。该机制中,SGSN使用双播Bicasting技术,使切换后的移动台能够尽快地接入到新的小区,减少了分组的丢失。仿真结果显示,新机制可以将切换过程中的分组丢失率减少15%左右。     

TD-SCDMA/GSM/GPRS双模终端CELL CHANGE ORDER过程研究

随着TD-SCDMA系统的商用,同时需兼容已非常成熟运营的GSM系统,TD-SCDMA/GSM/GPRS双模终端已是市场的主流。本文针对双模单待终端（协议控制）CELL CHANGE ORDER过程进行研究,该过程是双模终端实现PS域切换的一种重要方式。首先,以TD-SCDMA/GSM/GPRS系统高层协议为基础介绍了双模单待自动切换终端的CELL CHANGE ORDER过程的各个阶段：系统间测量、网络判决及小区改变执行;然后详细地设计了小区改变执行的正常及异常处理流程,并对如何实现数据平面切换过程进行了重点描述;最后搭建板级测试环境,进行协议一致性测试,验证了CELL CHANGE ORDER过程的实现。     

分组数据业务:从GSM到UMTS

本文主要介绍了分组数据业务在GSM(GPRS)网及其第三代系统UMTS中的发展情况,分析了它们的系统结构和无线接口协议栈,讨论了移动通信中分组模式与Internet的结合———移动IP在第三代系统中的应用。     

新一代AXE交换机

WCDMA、R99版本针对核心网(电路域与分组域)的解决方案是基于GSM网络结构的,其初衷是在3G网络部署初期,能够提供一个可“向后兼容”的网络方案。R99版本定义的核心网络的初步实施方案是UMTS和GSM的电路域、分组域业务分别由移动交换机(MSC)与GPRS服务节点     

利用SGSN本地解析功能实现池组内RNC间快速切换方法

用户在SGSN池组内进行数据业务时可能会发生RNC间切换,切换分为两种,一种是Intra SGSN即SGSN内部切换;另一种是Inter SGSN即SGSN间切换。显然,第2种切换是需要避免的。本文针对SGSN池组内的RNC切换问题进行研究,并且提出了一种利用SGSN的本地解析功能来实现快速切换的方法,经过测试验证,该方法很好地解决了池组内的RNC间的Inter SGSN切换问题。     

WCDMA核心网的演进

WCDMA版本介绍3GPP组织自从1998年12月成立以后,一直致力于WCDMA技术规范的制定和完善。3GPP制定的规范版本发展情况如图1所示。R99版本主要继承了前期ETSI标准化组织在WCDMA规范上的研究成果,在2000年3月功能框架冻结。R99主要特征包括:(1)核心网在逻辑上分为CS(电路域)和PS(分组域),保持了与2G(GSM/GPRS)核心网络结构的兼容性。(2)核心网和接入网之间的Iu接口基于ATM,其中CS业务基于ATM AAL2承载,分组业务基于ATM AAL5承载。(3)电路域只支持TDM传输技术。(4)分组域网络结构与GPRS基本一致,包括SGSN、GGSN、…     

压缩模式在WCDMA向GSM切换时的应用

一、系统间的切换过程 通常我们通过使用WCDMA/GSM双模终端来实现WCDMA和GSM两网的切换和重选.从GSM网络向WCDMA切换时,双模终端在GSM的空闲时隙完成对WCDMA网络的测量和搜索;而在WCDMA向GSM切换时,由于WCDMA为码分系统,在进行电路域业务时独占收发信机,UE不能调谐到GSM的频率对GSM系统进行测量和搜索.分组域业务对时延和业务连续性的要求较低,因此采用重选的方式,即UE在连接状态下先断开与源服务网络的连接,进入空闲模式,再搜索目标网络并重新建立连接.电路域业务对时延和业务的连续性有严格要求,不能采用断开连接的方式进行切换.     

GSM/UMTS的系统模型、网络结构及GPRS/IP分析

本文简述了GSM/UMTS的系统模型及主要接口 ,重点分析了一种可能的GSM/UMTS网络结构及其合理性 ,提出了一种支持多媒体业务的GPRS/IP结构及用户平面协议参考模型 ,最后指出了研究UMTS的重要性。     

Performance analysis of channel de-allocation schemes for dynamic resource allocation in GSM/GPRS networks

Channel de-allocation for GSM voice call (DASV) has been considered for dynamic resource allocation in GSM/GPRS networks. Two new de-allocation schemes are proposed: de-allocation for GPRS packet (DASP) and de-allocation for both GSM voice call and GPRS packet (DASVP). An analytic model with general GPRS data channel requirement is derived to evaluate the performance of the schemes in terms of GSM voice call incompletion probability, GPRS packet dropping probability, average GPRS packet transmission time and channel utilisation.     

UMTS/IMT-2000 based on wideband CDMA

The UMTS terrestrial radio access is based on wideband 4.096 Mchip/s DS-CDMA technology. UTRA will be connected to an evolved GSM core network for both circuit and packet services. A merger between ETSI/Europe and ARIB/Japan based on W-CDMA, a GSM core network, and a common frequency allocation according to the ITU Recommendation of 2 GHz makes a global IMT-2000 standard feasible. UTRA based on W-CDMA fully supports the UMTS/IMT-2000 requirements (e.g., support of 384 kb/s for wide-area coverage and 2 Mb/s for local coverage). Furthermore, the air interface has flexible support of mixed services, variable-rate services, and an efficient packet mode. Key W-CDMA features also include improved basic capacity/coverage performance compared to second-generation systems, full support of adaptive antenna arrays, support of hierarchical cell structures with interfrequency handover, and support of asynchronous inter-base-station operation. There have been no constraints due to the strong requirements for backward compatibility with second-generation systems. This has facilitated a high degree of flexibility and a future-proof air interface. Extensive evaluations by means of simulations and field trials have been carried out by a number of companies, and full system tests are ongoing. Consequently, W-CDMA technology can now be regarded as a mature technology, ready to provide the basis for UMTS/IMT-2000     

无线分组数据自适应技术

对于分组数据业务来说 ,如果用户有一个良好的连接 ,则蜂窝的频谱效率和数据速率都会得到长足的提高 ,全世界所有的蜂窝标准都利用了这一点来进行数据速率自适应 ,文中就以下几种系统描述数据速率自适应过程 :CDMA (IS - 95 ) ,宽带CDMA (CDMA2 0 0 0和UMTSCDMA) ,TDMA (IS - 136 )和GSM (GPRS和EDGE) ,并探讨一些尚待解决的问题     

运用系统仿真方法对GSM／GPRS网络性能的分析

在对GSM／GPRS网络中的信道分配、分组数据调度、功率控制、越区切换和链路自适应等机制等系统仿真的基础上,对一些反映网络性能的主要指标,如阻塞率、掉话率、信道利用率和数据平均传输速率等做出了一定的估计。对不同网络参数和算法对网络性能的影响规律也进行了分析。这为今后网络的优化提供了一定的策略和依据。     

Lightweight Secure Roaming Mechanism Between GPRS/UMTS and Wireless LANs

The third generation partner project (3GPP) has standardized general packet radio service (GPRS) and the universal mobile telecommunications system (UMTS) to provide cell phone communications and wireless Internet services. Although the data transmission rate is lower than that of wireless local area networks (WLANs), GPRS/UMTS covers larger areas. Hence, to achieve higher speed ubiquitous access, we propose a lightweight secure roaming mechanism (LSRM) that integrates GPRS/UMTS and WLAN. Taking advantage of these two technologies, LSRM offers anonymous roaming and friendly subscriber management. Besides, we give a formal security analysis to LSRM based on BAN authentication logic.     

GSM话音应用的未来

讨论在当前发展的三种无线通信网ＧＳＭ、ＧＰＲＳ和ＵＭＴＳ中,话音业务所承担的角色,介绍 ＧＳＭ话音应用的未来。     

A bandwidth-on-demand strategy for GPRS

General packet radio service (GPRS) is a global system for mobile communications (GSM) packet data service. In order to efficiently accommodate GPRS traffic while maintaining the desired service quality of GSM calls, we propose a GPRS bandwidth-allocation strategy called the bandwidth-on-demand (BoD) strategy. The BoD strategy is adaptive to the change of traffic conditions, and thus can dynamically adjust the number of channels for GSM and GPRS traffic. Taking the effect of packet dropping due to movements of mobile stations into account, this paper develops an analytical model to study the BoD performance in terms of GSM-call-blocking probability and GPRS-packet-dropping probability.     

Wireless Internet access for mobile subscribers based on theGPRS/UMTS network

With the advent of IP technologies and the tremendous growth in data traffic, the wireless industry is evolving its core networks toward IP technology. Enabling wireless Internet access is one of the upcoming challenges for mobile radio network operators. The General Packet Radio Service is the packet-switched extension of GSM and was developed to facilitate access to IP-based services better than existing circuit-switched services provided by GSM. We illustrate how a visited mobile subscriber on a GPRS/UMTS network can access his/her home network via the gateway GPRS support node (GGSN). We also propose some implementation ideas on wireless Internet access for a remote mobile subscriber based on a GPRS/UMTS network